JPS6198583A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having excellent picture stability by a method in which a specific compound as a developer is used and an under coat containing a specific bisphenol compound is provided adjacently to a thermal color-forming layer between a supporter and the thermal color- forming layer. CONSTITUTION:A compound of the formula (I) as a developer is used, and an under coat containing a bisphenol compound of the formula (II) is provided adjacently to a thermal color-forming layer between a supporter and the thermal color-forming layer. The preferred amount of the compound as a developer, as represented by the formula (I), is 1-5pts.wt. on the basis of 1pt.wt. leuco dye and the compound of the formula (II) is preferably used in a proportion of 0.5-4g/m<2> on the basis of the supporter.

Description

[Detailed description of the invention] 〔Technical field〕 The present invention relates to heat-sensitive recording materials, and more particularly.

A leuco dye that is colorless or slightly pale at room temperature.

The present invention relates to an improvement in a heat-sensitive recording material provided on a support with a heat-sensitive coloring layer containing as a main component a color developer which reacts with the leuco dye and develops color when heated.

[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.
It is widely used in the field of computer output, printers such as calculators, recorders for medical measurement, low and high speed facsimile fields, automatic ticket vending machines, thermal copying fields, labels for POS systems, etc.

The above-mentioned heat-sensitive recording materials are usually manufactured 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.

A thermosensitive coloring layer that develops color and records an image when heated contains a leuco dye and a color developer that reacts with the leuco dye and develops color when heated. In this case, as the leuco dye, for example, a colorless or light-colored leuco dye having a lactone, lactam or spiropyran ring is used, and as the color developer, various acidic substances are used. Such a combination of a leuco dye and a color developer has a clear color tone and less fog, and has thus far been applied to many heat-sensitive recording materials.

However, images obtained by a thermal reaction between leuco dye as a color-forming substance and an acidic substance such as a phenolic substance or an organic acid as a color developer cannot be obtained from plastics contained in food wrap, commuter pass, erasers, etc. It has the disadvantage that it can be discolored by chemicals, edible oils, organic solvents, alcohol, etc.

〔the purpose〕

An object of the present invention is to provide a heat-sensitive recording material that overcomes the problems of the prior art described above and has excellent image stability.

〔composition〕

According to the present invention, 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 formula (1) is used as the color developer. A heat-sensitive recording material characterized in that an undercoat layer containing a sulfonyl diphenol compound represented by the following formula (II) is provided adjacent to the heat-sensitive color-forming layer between the support and the heat-sensitive color-forming layer. provided.

Formula (I): Formula (■): The present inventors have discovered that when the compounds represented by formulas (1) and (II) are eutectic, the coloring part will not fade due to contact with water, oil, plasticizers, etc. However, it has been found that if these two types are contained in the same layer, there will be a problem that skin coloring will occur when stored at room temperature and humidity.

Therefore, as a result of further intensive research, the present inventors found that
The compound of formula (1) is contained in the heat-sensitive coloring layer, and the compound of formula (■)
It has been discovered that a heat-sensitive recording material that overcomes the above-mentioned drawbacks can be obtained by containing the compound in the undercoat layer provided between the support and the heat-sensitive coloring layer.

The color developer of formula (1) used in the present invention is generally 1 to 5 parts by weight, preferably 2.5 to 5 parts by weight, per 1 part by weight of the leuco dye.
4 parts by weight, and the bisphenol compound of formula (II) is 0.5 to 4 g/rx? , preferably 1
It is best to use it at a rate of ~3g/rlor.

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 of those applied to this type of heat-sensitive material may be used. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, and spiropyran-based 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-diethylaminophenyl, 3.3-bis(P-dimethylaminophenyl)-6-chlorophthalide.

3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluoran.

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-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-(N,N-diethylamino )-5-methyl-7-(
N.

N-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 6'-bromo-31 -Methoxy-benzoindolino-pyrylospirane.

3-(2'-Hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-chlorophenyl)phthalide.

3-(2'-Hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy-5'-ditrophenyl)phthalide.

3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-5'-methylphenyl)phthalide, 3-(2'-methoxy-4'-dimethylaminophenyl)-3-( 2'-hydroxy-41-chloro-51
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane.

3-Diethylamino-5-chloro-7-(N-benzyl-trifluoromethylanilino)fluoran.

3-pyrrolidino-7-(di-P-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-phenylethylamino)fluoran, 3-(N-ethyl-P-)luidino)- 7-(α-phenylethylamino)fluoran, 3-diethylamino-7-(0-methoxycarbonylphenylamino)fluoran.

3-diethylamino-5-methyl-7-(α-phenylethylamino)fluorane, 3-diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p2n
-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, various commonly used binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, methoxycellulose, hydroxyl, etc. Cellulose derivatives such as ethyl cellulose, carboxymethyl cellulose, methyl cellulose, and ethyl cellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acryl amide/acrylic ester/methacrylic acid ternary copolymer, styrene/ Maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt,
In addition to water-soluble polymers such as polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene-butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer, and Latex such as butyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used. These binders are also used as binders for undercoat layers.

In addition, in the present 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 conventionally used thermoplastic A sexual substance (or lubricant), etc. can be used in combination. In this case, examples of the filler include calcium carbonate and silica.

In addition to inorganic fine powders such as zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, and surface-treated calcium and silica, urea-formalin resin, styrene/methacrylic acid copolymer, Organic fine powder such as polystyrene resin can be mentioned, and conventionally used thermofusible substances include, for example, higher fatty acids or their esters, amides, or metal salts, as well as various waxes, aromatic carboxylic acids, etc. Condensation products with amines, benzoic acid phenyl esters, higher linear glycols, dialkyl 3°4-epoxy-hexahydrophthalates.

50-2 of higher ketones, other thermofusible organic compounds, etc.
Examples include those having a melting point of about 00°C.

The heat-sensitive recording material of the present invention can have various conventionally known structures. For example, a water-soluble polymer-containing protective film can be provided on the heat-sensitive coloring layer to improve oil resistance. . Such water-soluble polymers include polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, hydroxyethylcellulose, methylcellulose,
Carbo-dried dimethylcellulose, starch and its derivatives.

casein, sodium alginate, polyvinylpyrrolidone,
Examples include polyacrylamide, styrene-maleic acid copolymer, and the like. 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~
10 μl, preferably 2-5 μl.

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 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 bisphenol compound represented by Formula 1 (II) as a main component is provided on one side of the support, and further contains the above-mentioned fluoran compound and phenolic compound thereon. It is sufficient to provide a heat-sensitive coloring layer with a heat-sensitive color forming layer, and then provide a release mount on the other side of the support with an adhesive layer interposed therebetween.In the case of magnetic ticket paper, a ferromagnetic material and a binder can be used instead of this release mount. What is necessary is to provide a magnetic recording layer containing as a main component.

〔effect〕

The heat-sensitive recording material of the present invention has the above structure, is a heat-sensitive recording material with 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.

CA liquid] 10% polyvinyl alcohol aqueous solution 200〃Water
5
00//[Liquid B] 3-N-methyl-3-N-cyclohexylamino-6-
Methyl-7-anilinofluorane 300 parts 10% polyvinyl alcohol aqueous solution 300 water
400tz [
Solution C] Calcium carbonate 100 parts lO
% polyvinyl alcohol 200〃water
400
〃After dispersing the mixtures with the above compositions in a ball mill for 72 hours to prepare liquids A, B and C, liquid A was mixed with a basis weight of 50
An undercoat layer was provided by coating and drying on a high-quality paper of g/nf so that the amount of adhesion after drying was 4 g/nf.

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 weight of liquid B after drying was 0.5 g/rrr. A thermosensitive recording sheet of No. 1 was obtained.

Example 2 On the heat-sensitive color forming layer of the heat-sensitive recording material obtained in Example 1, a solution B having the following composition was applied so that the dry weight was 3 g/rf.
A protective layer was provided by drying to obtain a heat-sensitive recording material of the present invention.

cD liquid] Carboxy group-modified polyvinyl alcohol 50 parts Thermosetting organic filler lO〃Water resistant agent
5〃Water
500 copies Comparative Example 1~
4 As a comparative example, one obtained in the same manner as in Example 1 except that there was no undercoat layer made of liquid A (Comparative Example 1), and the same as in Example 1 except that diphenyl sulfone in liquid A was replaced with bisphenol A. (Comparative Example 2) and Example 1 (Comparative Example 3) were prepared in the same manner except that the compound of formula (1) in Liquid C was replaced with bisphenol A.

Furthermore, 10 parts of liquid B, 30 parts of liquid A, and 40 parts of liquid C were mixed,
This is adjusted so that the dry weight of liquid B is 0.5 g/rrr! The heat-sensitive recording material of Comparative Example 4 was obtained by coating and drying on high-quality paper of 50 g/rf.

After surface-treating the heat-sensitive recording materials of the present invention and comparative heat-sensitive recording materials obtained above using a super calender, they were printed using a facsimile machine with a built-in thermal head to examine color development, as well as the plasticizer resistance and oil resistance of the printed images. A test was conducted for durability and water resistance. The results are shown in Table 1. Each test was conducted as follows.

Color development: Color was developed using a facsimile equipped with a thermal head (head voltage 12 V), and its density was measured using a Macbeth densitometer.

Plasticizer resistance: The sample obtained in the color development test (head voltage 12V) was covered with a food wrap film containing a plasticizer, and a load of 100g/a# was applied in an environment of 40℃ for 24 hours. The density of the colored part after that was measured using a Macbeth densitometer.

Oil resistance: Cottonseed oil was applied to the colored area of the sample obtained in the color development test (head voltage 12V), and the concentration was measured using a Macbeth densitometer after being left in a 40°C environment for 24 hours.

Background density: The background density of the uncolored area was measured using a Macbeth densitometer.

Water resistance: The sample obtained in the color development test was immersed in water at 20° C. for 24 hours, and the concentration was then measured using a Macbeth densitometer.

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 formula (I) is used as the color developer, and a compound represented by the following formula (I) is used as the color developer. 1. A heat-sensitive recording material, characterized in that an undercoat layer containing a bisphenol compound represented by the following formula (II) is provided adjacent to the heat-sensitive color-forming layer between the support and the heat-sensitive color-forming layer. Formula (I): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ Formula (II): ▲There are mathematical formulas, chemical formulas, tables, etc.▼