JPS61291180A - Thermal recording material - Google Patents

Abstract

PURPOSE:To provide a thermal recording material having a high sensitivity and less susceptible to fading or blushing of recorded images, by a method wherein a specified compound is used as a color developer, and an undercoat layer comprising a specified compound is provided between a base and a thermal color forming layer adjacently to the color forming layer. CONSTITUTION:A compound of general formula (I) is used as a color developer and the undercoat layer comprising a compound of general formula (II) is provided between a base and a thermal color forming layer adjacently to the color forming layer, in a thermal recording material provided with a thermal color forming layer comprising a leuco dye and a color developer as main constituents on a base. In the formulas, n is 1 or 2, and R1 is 1-8C alkyl, cylcoalkyl or subst. or unsubst. aryl or aralkyl, wherein the substituent group may be halogen, alkoxyl or the like. The compound of general formula (I) has a high color developing capability and, therefore, high heat response characteristics and excellent uniformity of developed color image. The compound of general formula (II) prevents recrystallization of a developed color part when being co-melted with the bisphenol compound of general formula (I), and can therefore prevent fading or blushing phenomenon from being caused by oils, plasticizers or the like.

Description

[Detailed Description of the Invention] [Technical Field] The present invention relates to a heat-sensitive recording material, and more particularly, it comprises a leuco dye that is colorless or slightly pale at room temperature, and an acidic substance that reacts with the leuco dye under heat to develop a color. The present invention relates to an improvement in a heat-sensitive recording material in which a heat-sensitive color forming layer containing a heat-sensitive coloring layer as a main component is provided on a support.

[Prior art]

Recently, various recording materials have been researched and developed and put into practical use in the information recording field, in response to social demands such as diversification and increase in information, resource conservation, and pollution-free technology.Among them, thermal recording materials are (1) A colored image is recorded simply by heating, eliminating the need for a complicated development process. (2) It can be produced using a relatively simple and compact device, and the resulting recording material is easy to handle. (3) paper is often used as the support;
In this case, not only the cost of the support is low, but also the feel of the obtained recording material is similar to that of plain paper. Recorder field, low and high speed facsimile field, automatic ticket vending machine field, thermal copying field, 1
] Widely used in the label field of OS systems.

The above-mentioned heat-sensitive recording materials are usually produced by coating a support such as paper, synthetic paper, or synthetic resin film with a heat-sensitive coloring layer solution containing a coloring component that can cause a coloring reaction when heated, and then drying it. A colored image is recorded on the heat-sensitive recording material thus obtained by heating it with a thermal pen or a thermal head. Conventional examples of such heat-sensitive recording materials include, for example, the heat-sensitive recording materials disclosed in Japanese Patent Publication No. 43-4160 or Japanese Patent Publication No. 45-14039; Responsiveness was low, and sufficient color density could not be obtained during high-speed recording. As a method for improving such drawbacks, for example, JP-A No. 49-38424 discloses the use of nitrogen-containing compounds such as acetamide, stearamide, m-nitroaniline, and di-1-lyl phthalate; The publication describes aceto acid-resistant anilide as described in JP-A-53-11036.
In the publication, N,N-diphenylamine derivatives, benzamide derivatives, and carbazole derivatives are disclosed in JP-A-53-39.
+3! 'l Kano publication contains alkylated biphenyls and biphenylalkanes, and JP-A-56-+44]93 contains P-oxybenzoic acid ester derivatives. Several methods have been disclosed, among which the most effective method is known to use a 1)-oxybenzoic acid ester derivative as a color developer.

However, these various color developers still have drawbacks such as fading of the recorded image and whitening of the image area (white powder is generated on the surface). In order to improve such drawbacks, it is known to use a compound represented by the following general formula N), but in this case, nl+
, IIR plasticizers, etc. are causing discoloration.

(In the formula, n represents 1 or 2) [Object] The object of the present invention is to provide a high-sensitivity thermal recording material that improves the conventional drawbacks listed in -1-, that is, to provide a highly sensitive and recording material. To provide a heat-sensitive recording material in which images are less likely to fade or whiten.

〔composition〕

According to the present invention, there is provided a heat-sensitive recording material in which a heat-sensitive color forming layer containing a leuco dye and a color developer as main components is provided on a support, and the color developer is represented by the following general formula (1). A thermosensitive recording characterized in that an undercoat layer containing a compound represented by the following general formula (TI) is provided between the support and the thermosensitive coloring layer and adjacent to the thermosensitive coloring layer. Materials provided.

General formula (I): In the formula, n represents 1 or 2.

General formula (■): In formula 4, R3 represents a C1 to C8 alkyl group, a cycloalkyl group, a substituted or unsubstituted aryl group, or an aralkyl group. In this case, examples of the substituent include a halogen atom and an alkoxyl group.

As described in -, the present invention uses the general formula (
A bisphenol compound represented by 1) is used. Since such compounds have high color developing ability, they have higher thermal responsiveness than conventional color developers such as 4゜4'-isopropylidene bisdiphenol and 4,4'-butylidene diphenol. Furthermore, the uniformity of the colored image is also excellent. On the other hand, when the compound represented by the general formula (r[) is eutectic with the bisphenol compound of the general formula (1), discoloration or whitening due to oils, plasticizers, etc. may occur in order to prevent recrystallization in the coloring part. can be prevented. However, the compound of the general formula (TI) has a strong color developing ability, so if it is used in combination with a leuco dye and a compound of the general formula (TI) in an amount sufficient to obtain the above effect, it has the disadvantage of causing slight fogging of the heat-sensitive liquid. .

In the case of the present invention, this drawback is overcome by using the compound of general formula (1) in the undercoat layer.

Specific examples of the compound represented by the general formula (11) include the following.

(1) 2-hydroxy 6-naphthoic acid methyl ester (
2) 2-hydroxy 6-naphthoic acid ethyl ester (3
) 2-hydroxy 6-naphthoic acid n-propyl ester (4) 2-hydroxy 6-naphthoic acid n-propyl ester (5) 2-hydroxy 6-naphthoic acid n-butyl ester (6) 2-hydroxy 6-naphthoic acid n-propyl ester -naphthoic acid] SO-butyl ester (7) 2-hydroxy 6-naphthoic acid sec butyl ester (8) 2-hydroxy 6-naphthoic acid cyclohexyl ester J Shikoku 9) 2-hydroxy 6-naphthoic acid phenyl ester (10) 2 -Hydroxynaphthoic acid p-chlorophenyl ester (II) 2-hydroxy 6-naphthoic acid 0-chlorophenyl ester (12) 2-hydroxy 6-naphthoic acid benzyl ester (13) 2-hydroxy 6-naphthoic acid m-methylbenzyl ester ( 14) 2-hydroxy 6-naphthoic acid P-chlorobenzyl ester (+5) 2-hydroxy 6-naphthoic acid phenethyl ester (16) 2-hydroxy 6-naphthoic acid O-chlorobenzyl ester (17) 2-hydroxy 6-naphthoic acid P-chlorobenzyl ester Acid p-methylbenzyl ester (18) 2-hydroxy 6-naphthoic acid 0-methoxybenzyl ester, etc.

The color developer used in the present invention is generally 1 to 5 parts by weight, preferably 2.5 to 4 parts by weight, per 1 part by weight of the leuco dye. 0.5~4
g/rd, preferably 1 to 3 g/n.

The leuco dyes used in the present invention can be applied singly or in combination of two or more types, but such leuco dyes include:
Any dye that has been applied to this type of heat-sensitive material may be used. For example, leuco compounds of dyes such as triphenylmethane, fluoran, phenothiazine, auramine, and spiropyran dyes 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- 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-(N-p-tolyl-N-ethylamino)-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-MJchloromethylanilino)fluoran, 3-diethylamino-7-(0- chloroanilino)fluoran, 3-dibutylamino-7-(0-chloroanilino)fluoran, 3-N-methyl-N-amylamino-6-methyl-7-
Anilinofluorane, 3-N-methyl-N-cycloL1 hexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N,N -diethylamino)-5-methyl-7-(
N.

N-dibenzylamino) fluorane, benzoylleucomethylene blue, 6'-chloro-8'-me-1-xy-benzoindolino-
virillospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospiran, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl) phthalide, 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-diherophenyl)phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl) )-3-(2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5
'-Methylphenyl)phthalide, 3-morpholino-7-(N-propyl-1-lifluoromethylanilino)fluoran, 3-pyrrolidino-7-1-lifluoromethylanilinofluoran, 3-diethylamino-5- Chloro-7-(N-benzyl-trifluoromethylanilino3-pyrrolidino-7-(di-ρ-thalolphenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluorane, 3 -(N-ethyl-ρ-l~luidino)-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-methyl 1-luidino)-7-(p-
〇-butylanilino)fluorane, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
', 5'-benzofluorane, etc.

In the present invention, in order to bind and support the leuco dye and color developer on the support L, various conventional binders can be used as appropriate, such as polyvinyl alcohol,
Starch and its derivatives, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose,
Cellulose derivatives such as methylcellulose and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone,
Acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt, imbutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin,
In addition to water-soluble polymers such as casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, etc. Latexes such as polymers and styrene/butadiene/acrylic copolymers can be used. Also,
These binders are also used as binders for undercoat layers.

Also, are you talented in this invention? In addition to the leuco dye and color developer, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, and conventional heat-fusible substances (or lubricant) etc. can be used in combination. In this case, fillers include, 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, and conventionally used thermofusible substances include, for example,
In addition to higher fatty acids or their esters, amides, or metal salts, various waxes, condensates of aromatic carboxylic acids and amines, phenyl benzoate, higher linear glycols, dialkyl 3゜4-epoxy-hexahydrophthalate. , higher ketones, other thermofusible organic compounds, etc.
Examples include those having a melting point of about 200°C.

The heat-sensitive recording material of the present invention can have various conventionally known structures. For example, oil resistance can be improved by providing a protective layer containing a water-soluble polymer on the heat-sensitive coloring layer. Examples of such water-soluble polymers include polyvinyl alcohol, carboxyl-modified polyvinyl alcohol, hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, starch and its derivatives, casein, sodium alginate, polyvinylpyrrolidone, polyacrylamide, and styrene-maleic acid copolymer. Examples include merging. Further, for the purpose of improving the water resistance of this protective layer and the matching property with the thermal head, a waterproofing agent, a thermosetting organic flyer material, wax, etc. can be contained in the protective layer. The thickness of the protective layer is usually 1 to 10 μm, preferably 2 to 5 μm.

The heat-sensitive recording material of the present invention can be produced, for example, by applying a coating liquid for forming a heat-sensitive layer containing the above-mentioned components onto a suitable support such as paper, synthetic paper, or plastic film, and drying it. It is used in the field of recording, especially as a heat-sensitive recording material for high-speed recording that requires high image stability.

The heat-sensitive recording material of the present invention is used in various fields, but in particular, it takes advantage of the above-mentioned excellent color image stability,
It can be advantageously used as a heat-sensitive recording type label sheet 1- or a heat-sensitive recording type magnetic ticket paper. In the case of a heat-sensitive recording type label sheet, an undercoat layer containing a compound represented by the general formula (FT) as a main component is provided on one side of the support, and the above-described fluoran compound and phenolic compound are further applied on the undercoat layer. It is sufficient to provide a heat-sensitive coloring layer containing a ferromagnetic material and a release mount on the other side of the support via an adhesive layer. A magnetic recording layer containing adhesive as a main component may be provided.

〔effect〕

The heat-sensitive recording material of the present invention has the above-mentioned structure, and is a heat-sensitive recording material with high color development sensitivity and excellent image reliability, and is applied to various fields.

〔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.

[Liquid A]

2-hydroxy-6-naphthoic acid benzyl ester 200 parts lO
% polyvinyl alcohol aqueous solution 200 parts water
500
Part [Liquid B] 3-N-methyl-3-N-cyclohexylamino-6-
Methyl-7-anilinofluorane 300 parts 10% polyvinyl alcohol aqueous solution 300 parts water
400 copies [
Solution C] 1.7-di(4-hydroxyphenylthio)3.5-dioxaheptane 200 parts Calcium carbonate 100 parts 10% polyvinyl alcohol 200 parts Water
400 parts of the mixture with the above composition was dispersed in a ball mill for 72 hours to obtain liquid A,
After preparing liquids B and C, liquid A was coated and dried on high-quality paper with a basis weight of 50 g/m so that the coating weight after drying was 4 g/m to form an undercoat layer.

Next, 10 parts of liquid B and 40 parts of liquid C were mixed, and this was applied and dried on the undercoat layer so that the dry weight of liquid B was 0.5 g/m. A thermosensitive recording material No. 1 was obtained.

Example 2 Liquid 1 of the following composition was applied to 1- of the heat-sensitive coloring layer of the heat-sensitive recording material obtained in Example 1 at a dry Eastern European weight of 3 g/nr, and dried to form a protective layer. Obtained recording materials.

D-liquid Carboxy-modified polyvinyl alcohol 50 parts Thermosetting organic filler 10 parts Water resistant agent
5. .

water
500 l! Comparative Examples 1 to 2 Comparative examples include those of Example 1 except for Undercoat 1 to (Comparative Example 1) and [C] 1,7-di(4-hydroxyphenylthio) in the liquid of Example 1. =3,
A product (Comparative Example 2) was prepared in the same manner except that 5-dioxahebutane was replaced with bisphenol A.

After surface-treating the obtained heat-sensitive recording materials of the present invention and comparative heat-sensitive recording materials using a super calender, they were printed using a facsimile machine with a built-in thermal head to examine color development, and the 4R plasticity resistance of the printed image was Tests were conducted for durability and oil resistance. The results are shown in Table-1.

In addition, each test was conducted as follows.

Color development... Color is developed using a facsimile with a thermal spatula 1- (head voltage 9V to 12V), and the density is set to Macbeth's dark no σd1? Jll+ was established.

1TWJ agent resistance... Sample obtained from color development test 1- (
A head voltage of 12 V) was covered with a food wrap film containing a plasticizer, a load of 100 g/c was applied in an environment of 40°C, and the density of the colored part was measured at Macbeth density H1 after 24 hours. did.

Oil resistance: Apply cottonseed oil to the colored part of the sample obtained in Color development test 1 (head voltage 12V), leave it in an environment at 40°C for 24 hours, and measure the concentration using a Macbeth densitometer.
It has been decided.

Table-1

Claims (1)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive color forming layer containing a leuco dye and a color developer as main components is provided on a support, a compound represented by the following general formula (I) is used as the color developer, and A heat-sensitive recording material, characterized in that an undercoat layer containing a compound represented by the following general formula (II) is provided adjacent to the heat-sensitive color-forming layer between the support and the heat-sensitive color-forming layer. General formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, n represents 1 or 2) General formula (II) ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 is C_1 ~ C_8 alkyl group, cycloalkyl group, substituted or unsubstituted aryl group or aralkyl group)