JPS62257884A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having high sensitivity, less susceptible to deterioration of images with time and enhanced in reliability, by using a compound of specified general formula as a color developer. CONSTITUTION:A compound of general formula I, wherein R is a 10C or higher alkyl, substd. or unsubstd. aryl or aralkyl, is used as a color developer in a thermal recording material utilizing a color forming reaction between a leuco dye and the color developer. Examples of the compound of general formula I include those in which R is a 10C or higher alkyl such as lauryl and stearyl, those in which R is an aryl such as phenyl and naphthyl, and those in which R is an aralkyl such as benzyl and phenethyl. At least one of these compounds may be used either singly or in combination. A thermal recording material is produced by, for example, applying a coating liquid containing the leuco dye and the color developer for forming a thermal recording layer to an appropriate base such as a paper, a synthetic paper and a plastic film, followed by drying.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material, and more specifically, it comprises a leuco dye that is colorless or slightly pale at room temperature, and a color developer that reacts with the leuco dye when heated 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 color-forming component is provided on a support.

[Prior art]

Thermosensitive recording materials generally consist of a support such as paper, synthetic paper, or plastic film provided with a thermosensitive coloring layer containing a thermochromic composition as a main component.
A colored image can be obtained by heating with a strobe lamp or the like. Compared to other recording materials, this type of recording material
It has the advantages of being able to obtain records in a short time with a relatively simple device without complicated processes such as fixing, generating less noise and polluting the environment, and being inexpensive.
In addition to being used for copying books, documents, etc., it is also widely used as a recording material in a wide variety of applications, including electronic computers, facsimile machines, ticket vending machines, labels, and recorders. The thermochromic composition used in such heat-sensitive recording materials consists of a general coloring agent and a color developer that causes the coloring agent to develop a special color under heat.
Colorless or light-colored leuco dyes having a lactone, lactam or spiropyran ring have been used as color formers, and organic acids and phenolic substances have been used as color developers. A recording material made of a combination of a color forming agent and a color developing agent has the advantage that the obtained image has a particularly clear color tone, has a high background whiteness, and has excellent weather resistance. , is widely used.

Conventionally, bisphenol A and P-hydroxybenzoic acid esters have been used as color developers for leuco dyes, but although these phenols have a high color density, they lack the stability of colored images, so they cannot be left alone. It has the disadvantage that the concentration decreases, and the concentration decreases at high temperatures or at high temperatures.

On the other hand, JP-A-59-145189 and 59-145190
It has been proposed to use a metal salt of an organic acid as a color developer, as described in 2006, but although this product has good stability, it has the disadvantage of poor sensitivity.

〔the purpose〕

The present invention overcomes the problems of the prior art, viz.

It is an object of the present invention to provide a heat-sensitive recording material which is highly sensitive and has improved reliability with little image deterioration over time.

[Structure] 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, characterized in that a compound represented by the following general formula is used as the color developer. Recording materials.

(In the formula, R represents an alkyl group having 10 or more carbon atoms, a substituted or unsubstituted aryl group, or an aralkyl group.) As a specific example of the compound of the general formula (1) used in the present invention, for example, R is Examples include compounds of higher alkyl groups having 10 or more carbon atoms such as stearyl groups, aryl groups such as phenyl groups and naphthyl groups, and aralkyl groups such as benzyl groups and phenethyl groups. It is not limited.

Each of these compounds can be used alone.

A mixture of two or more types may be used. Further, it is preferable that the amount used by the company used is in the range of 0.1 to 10 parts by weight per 1 part by weight of the dye.

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:
Those applied to this type of heat-sensitive material can be arbitrarily applied. For example, leuco compounds of dyes such as triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-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-dibutylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-6-chlorophthalide, 3.3-bis(p-dibutylaminophenyl) phthalide.

3-Cyclohexylamino-6-chlorofluorane.

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-anilino Fluoran, 2-(N-(3'-hlifluoromethylphenyl)amino)-6-dinithylaminofluorane, 2-(3,6
-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(m-trichloromethyl7nilino)
Fluoran, 3-diethylamino-7-(0-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-benzoindolinopyrylospirane, 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-41-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-)dinylethylamino)fluoran, 3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3- Diethylamino-7-piperidinofluorane, 2-
Chloro-3-(N-methyltoluidino)-7-(p-n
-butylanilino)fluorane.

3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-methyl-7-mesitidino 4
',5'-benzofluorane, 3.6-simethoxyfluorane, 3-(p-dimethylaminophenyl)-3-phenylphthalide, 3-di(1-ethyl-2-methylyldol)-3 -yl-phthalide, 3-diethylamino-6-phenyl-7-azafluorane.

3.3-bis(p-diethylaminophenyl)-6-dimethylaminophthalide, 2-bis(p-dimethylaminophenyl)methyl-5-
Dimethylamino-benzoic acid, 3-(ρ-dimethylaminophenyl)-3-(p-dibenzylaminophenyl) phthalide.

3-(N-ethyl-N-n-7 mil)amino-6-methyl-7-anilinofluorane and the like.

In addition, in the present invention, in addition to the color developer represented by the general formula (summer), conventionally known color developers such as phenolic substances, inorganic/organic acidic substances and their derivatives, and metal complexes are used in combination. You can also do that. Specific examples thereof include phenolic substances, organic or inorganic acidic substances, and esters and salts thereof as shown below.

gallic acid, salicylic acid, 3-isopropylsalicylic acid,
3-cyclohexylsalicylic acid, 3,5-di-tert-
Butylsalicylic acid, 3,5-di-α-methylbenzylsalicylic acid, 4,4'-isopropylidenediphenol,
4.4'-isopropylidene bis (2-chlorophenol), 4,4'-isopropylidene bis (2,6-dibromophenol), 4,4'-isopropylidene bis (2,6-dichlorophenol), 4 .4'-isopropylidene bis(2-methylphenol), 4,4'-isopropylidene bis(2,6-dimethylphenol),
4,4'-isopropylidene bis(2-tert-butylphenol), 4,4'-5ee-butylidene diphenol, 4,4'-cyclohexylidene bisphenol, 4,4'-cyclohexylidene bis(2-methyl phenol), 4-tert-butylphenol,
4-phenylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 3.5-xylenol, thymol, methyl-4-hydroxybenzoate, 4-hydroxyacetophenone, novolac type phenolic resin, 2.2'-thiobis (4,6-dichlorophenol), catechol, resorcinol, hydroquinone,
Pyrogallol, phloroglycin, phloroglycin carboxylic acid, 4-tert-octylcatechol, 2,2'-
Methylenebis(4-chlorophenol), 2,2'-methylenebis(4-methyl-6-tart-butylphenol), 2,2'-dihydroxydiphenyl, P-hydroxyben79, ethyl frate, propyl P-hydroxybenzoate , butyl P-hydroxybenzoate, benzyl P-hydroxybenzoate, 1,7-bis(4-hydroxyphenylthio)-3,5-dioxahebutane, p-chlorobenzyl P-hydroxybenzoate, P-hydroxy Benzoic Ml-o-chlorobenzyl, p-hydroxybenzoic acid-p-methylbenzyl, p-hydroxybenzoic acid-n
-Octyl, benzoic acid, zinc salicylate, 1-hydroxy-2-naphthoic acid, 2-hydroxy-6-naphthoic acid, zinc 2-hydroxy-6-naphthoate, 4-hydroxydiphenylsulfone, 4-hydroxy-4'- Chlorodiphenylsulfone, bis(4-hydroxyphenyl)
Sulfide, 2-hydroxy-p-toluic acid, 3,5
-zinc di-tert-butylsalicylate, tin 3,5-di-tert-butylsalicylate, tartaric acid, oxalic acid, maleic acid, citric acid, succinic acid, stearic acid, 4-hydroxyphthalic acid, boric acid, thiourea derivative, 4 -Hydroxythiophenol derivatives, 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, and specific examples thereof include the following: Can be done.

Polyvinyl alcohol, starch and its derivatives, cellulose derivatives such as methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, sodium polyacrylate,
Polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali In addition to water-soluble polymers such as salt, polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene/butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer , polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/
Butadiene/acrylic copolymer, etc.

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, thermofusible 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. Examples of thermofusible substances include higher fatty acids or their esters, amides, or metal salts. In addition, various waxes, condensates of aromatic carboxylic acids and amines, benzoic acid phenyl esters, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones, and other thermofusible organics. Examples include compounds having a melting point of about 50 to 200°C.

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, a heat-sensitive coloring layer containing the above-described leuco dye, color developer, and metal compound is provided on one side of the support, and a heat-sensitive coloring layer containing the above-mentioned leuco dye, color developer, and metal compound is provided on the other side of the support through an adhesive layer. It is sufficient to provide a peel-off mount, and in the case of magnetic ticket paper, it can be replaced with this peel-off mount.

A magnetic recording layer containing a ferromagnetic material and a binder as main components may be provided.

It is also possible to use the leuco dye and color developer as a heat-sensitive transfer material provided on separate supports.

〔effect〕

Since the heat-sensitive recording material of the present invention contains at least one compound represented by the general formula (1), compared to conventional heat-sensitive recording materials, the recorded image fades over time and is more resistant to changes in temperature and humidity. Little fading.

〔Example〕

The present invention will now be explained in more detail with reference to Examples.

Note that all parts and percentages below are based on weight.

Example 1 [Liquid A] 3-(N-methyl-N-cyclohexyl)amino-6-
Methyl-7-7nilinofluorane 10 parts 10% aqueous solution of hydroxyethylcellulose 10 parts water
80 copies [
Solution B] 10% polyvinyl alcohol aqueous solution 20 parts calcium carbonate 20 parts water
50 copies (R=C
10 parts of the mixtures having the above compositions were ground and dispersed using a sand grinder for 2 to 4 hours to prepare liquids A and B.

Next, a heat-sensitive coloring layer coating solution was prepared by mixing and stirring so that the weight ratio of solution A and solution B was 1=3, and after drying, the coating amount after drying was 5. Labo Coat In Blonde was coated and dried at a concentration of 0 g/rd.

This coated paper was calendered to a smoothness of 700 to 1200 seconds to prepare a heat-sensitive recording material of the present invention.

Example 2 Compound represented by the general formula of liquid B in Example 1 (R=
The same procedure as in Example 1 was carried out except that 10 parts of CzsHzt) was changed to 5 parts of R''CttH*s, 10 parts of benzyl P-hydroxybenzoate was used, and the coating amount after drying was 5.8 g/rf. A heat-sensitive recording material of the present invention was obtained.

Example 3 Benzyl P-hydroxybenzoate of liquid B in Example 1 was replaced with bisphenol A, and a compound represented by the general formula (
A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except that R=C1, H, .) was changed to R=CH2 ().

Comparative Example 1 In Example 2, the compound represented by the general formula of [Liquid B] (
A comparative heat-sensitive recording material was obtained in the same manner as in Example 2 except that R=C knee 02 g).

Comparative Example 2 In Example 3, the compound represented by the general formula of [Liquid B] (
A heat-sensitive recording material for comparison was obtained in the same manner as in Example 3 except that R=CH2-O).

The above heat-sensitive recording materials were tested for image density, background density, and humidity and heat storage stability. The results are shown in Table-1.

■Image density: Head power 601i1/dot, ■Line recording time 5 using a printing experiment device manufactured by Matsushita Electronics Parts and equipped with a thin film head.
ms/n, scanning line density 8 x 3.85 dots/am, pulse width 1, 0 ms, and print density was measured using Macbeth Densitometer RD-514 (filter
106).

(2) Humid and heat resistant storage property Samples printed with the last pattern (2) were left at 40° C. and 90% RH or less for 24 hours, and then the density was measured and evaluated.

Table 1 As is clear from the results in Table 1, the heat-sensitive recording material of the present invention has superior image stability compared to conventional materials.

Procedural amendment band August 5, 1988 Commissioner of the Patent Office Black 1) Mr. Yu Aki 1, Indication of the case 1988 Patent Application No. 101696 2, Name of the invention Thermal recording material 3, Person making the amendment Relationship with the case Patent applicant address: 1-3-6 Nakamagome, Ota-ku, Tokyo Name:
(674) Ricoh Co., Ltd. - Representative Hama 1) Hiro 4, Agent 〒151 Address 1-58-10-5 Yoyogi, Shibuya-ku, Tokyo
Date of amendment order Voluntary 6, Number of inventions increased by amendment 07, Column 8 of "Detailed explanation of the invention" of the specification subject to amendment, Contents of amendment The following amendments will be made in the specification of the application.

(1) Delete “and metal compounds” on page 15, lines 14 and 15.

Claims (1)

[Claims] (1) A heat-sensitive recording material that utilizes a color-forming reaction between a leuco dye and a color developer, characterized in that a compound represented by the following general formula is used as the color developer. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R represents an alkyl group having 10 or more carbon atoms, a substituted or unsubstituted aryl or aralkyl group.)