JPS60105585A - Two-color thermal recording material - Google Patents

Abstract

PURPOSE:To enhance a color separating property, by successively laminating a high temp. color forming layer containing a leuco dye and a phenolic compound, an intermediate layer containing a color erasing agent and a low temp. color forming layer containing the leuco dye and a thiourea derivative onto a support. CONSTITUTION:A high temp. color forming layer containing a leuco dye and a phenolic compound is formed onto a support on which an intermediate layer represented by formula I is formed. Further, a low temp. color forming layer containing a leuco dye represented by formula II (wherein R<1> and R<2> are an 1-4C alkyl group and R<2> is chlorine or fluorine) and a thiourea derivative represented by formula III (wherein R<4> and R<5> are hydrogen, halogen, trifluoromethyl or an 1-4C alkyl group) is formed to obtain a two-color thermal recording material. Furthermore, an intermediate layer comprising a thermoplastic substance can be provided between the high temp. color forming layer and the color erasing intermediate layer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a leuco two-color heat-sensitive recording material.

[Prior art]

A thermosensitive recording material is a material in which a thermosensitive coloring layer capable of forming a colored image by heating is provided on a support such as paper, and a thermal printer equipped with a thermal head is widely used for heating.

These conventional heat-sensitive recording materials contain a colorless or light-colored leuco dye (color-forming main agent) containing raftone rings, lactam rings, spiropyran rings, etc. in the heat-sensitive color-forming layer; Color developer (color development aid)
Those containing these are widely used because they have clear color tones and less fogging.

By the way, heat-sensitive recording materials can easily produce colored images just by heating them, so they are not only used for copying books and documents, but also for recording various types of information such as electronic computers, facsimiles, Hachirex, etc., as well as output records from measuring machines. It is used in various fields, but depending on the purpose of recording, in order to display particularly necessary data or numbers more clearly, it is possible to record by changing the color of that part (display color) from the color of other parts. Of course, this is desirable.

Recently, attempts have been made to obtain multicolor records using differences in heating temperature or thermal energy.

Accordingly, various multicolor thermosensitive recording papers have been proposed. Multi-color thermosensitive recording paper is generally formed by stacking two types of high-temperature and low-temperature coloring layers that develop different tones with different coloring heat energies on a support, and can be broadly classified into the following two types: Divided into types. One is to mix the color with the color tone of the low temperature coloring layer when coloring the high temperature coloring layer to obtain a color tone different from the coloring tone of the low temperature coloring layer, and the other is to color the high temperature coloring layer. In this case, by using a decoloring agent that decolorizes the low-temperature color-forming layer, only the color tone of the high-temperature color-forming layer is obtained without color mixture of the color tone of the low-temperature color-forming layer.

As a specific example of these, the former is
Publication No. 9, Special Publication No. 49-4342, Special Publication No. 49-27
No. 708, Japanese Unexamined Patent Publication No. 48-86543, Special Hnt
J49-65239, etc., and the latter is described in Japanese Patent Publications No. 50-17865 and Japanese Patent Publication No. 50-1.
Publication No. 7866, Special Publication No. 51. -29024 Publication, Japanese Patent Publication No. 1987-87542, Japanese Patent Application Publication No. 1875-18048
The method is disclosed in Japanese Patent Application Laid-Open No. 53-47843, etc.

However, in the case of the former multicolor thermosensitive recording paper,
During high-temperature color development, the color tones that can be achieved are limited to black threads that have a strong high-temperature color tone, such as red-black and blue-black, because they are mixed with the color tone of the low-temperature color layer. There are drawbacks. On the other hand, in the case of the latter multicolor thermosensitive recording paper, the combination of color tones can be freely selected, but when coloring at high temperatures, high aliphatic alcohols, polyethers, polyethylene glycol derivatives,
Acetamide, stearamide, phthalonitrile as nitrogen-containing organic compounds, and guanidine derivatives as amine derivatives have been proposed, but with conventional configurations, when coloring at high temperatures, not only the low-temperature coloring layer but also the high-temperature coloring layer disappears. This had the disadvantage that it produced a color effect and became unclear. Furthermore, most two-color thermal paper has color combinations such as (blue-red) and (green-red), and no combination of (black-red) has been proposed.

〔the purpose〕

An object of the present invention is to provide a leuco-based two-color heat-sensitive recording material that has improved color separation properties and does not cause color mixture in high-temperature colored images.

〔composition〕

That is, according to the present invention, at least three layers, a high temperature coloring layer, an intermediate layer containing a decoloring agent, and a low temperature coloring layer, are laminated in this order on a support, and the high temperature coloring layer contains a leuco dye. Contains a phenolic compound, and the intermediate layer has the following general formula (
A two-color thermosensitive recording material is provided, which contains a decolorizing agent represented by A), and a low-temperature coloring layer contains a leuco dye and a thiourea derivative represented by the following general formula (B).

General formula (Δ) 2 General formula (B): 21 (wherein, R1 and R2 are alkyl groups having 1 to 4 carbon atoms, R
3 is chlorine or fluorine. ) General formula (C): (In the formula, R4 and R5 are hydrogen, halogen, trifluoromethyl group, or an alkyl group having 1 to 4 carbon atoms) In the present invention, the general formula (A ) Specific examples of the compound represented by the formula include the following.

Specific examples of the leuco dye represented by the general formula (b) include 1, 3-dibutylamino-7-riroloanilinofluoran, 3-diethylamino-7-chloroanilinofluoran, 3-dibutyl Examples include amino-7-fluoroanilinofluorane.

Further, as specific examples of the thiourea derivative as a color developer represented by the general formula (C), for example, N,N'-diphenylthiourea, N-p-ethylphenyl-N'-phenylthiourea, N -P-butylphenyl-N'-phenylthiourea, N,N'-di-chlorophenylthiourea, N,N'-di-p-cumerolophenylthiourea, N,N'-g1-trifluoromethylphenyl Examples include thiourea, N,N'-di-m-methylphenylthiourea, and the like.

On the other hand, examples of the color developer to be contained in the high-temperature coloring layer include 4-hydroxyphenoxide, 4-t-butylphenol, 4-hydroxyacetophenone, resorcinol, α-naphthol, thymol, β-naphthol, catechol, hydroquinone, and pyrogallol. , phloroglucin,
Phloroglucincarboxylic acid, 4,4'-5ec-butylidene diphenol, 4,4'-isopropylidene-
Bis(2-butylphenol), 4-t-octylcatechol.

4'-5ec-butylidene diphenol, 2,2'-dihydroxydiphenyl, 2,2'-methylene-bis(
Examples include 4-methyl-6-t-butylphenol), 2,2-bis(4'-oxyphenyl)propane (also known as bisphenol, and 3,5-xylenol).

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, such as i-rephenylmethane-based, fluoran-based,
Leuco compounds of dyes such as phenothiazine, auramine, and spiropyran dyes are preferably used. Particularly preferable examples of such leuco dyes include, for example, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-6-methyl-7-chlorofluorane, 3-cyclohexylamino-chlorofluorane, 3-
Examples include diethylaminobenzo[α]fluoran.

In the present invention, in order to bind and support the leuco dye and color developer on a support, various commonly used binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, methoxycellulose, etc. , cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylamide/acrylic acid ester copolymer, acrylamide/acrylic acid 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 ester, vinyl chloride/vinyl acetate copolymer, and Latex such as butyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

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 two-color thermosensitive recording material of the present invention can be modified in various ways. For example, in order to completely prevent the influence of the decoloring effect of the intermediate layer decoloring agent on the high temperature coloring layer during high temperature coloring, An interlayer, such as a layer of thermofusible material, can be provided between the high temperature color forming layer and the decolorizer interlayer.

〔effect〕

The two-color thermosensitive recording material of the present invention has the above-mentioned structure, and when coloring is performed at a high temperature, the decoloring agent contained in the intermediate layer acts on the coloring reaction system of the low-temperature coloring layer to decolorize the low-temperature coloring image. It does not affect the high temperature coloring layer. Therefore, the two-color image formed from the heat-sensitive recording material of the present invention has good color separation and provides a clear low-temperature color image and a high-temperature color image.

〔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.

Example 1 The following components were each pulverized and dispersed for 24 hours using a ball mill to prepare dispersions A, B, C and D.

[Dispersion liquid-A]

3-Dibdelamino-7-20 parts Chloroanilinofluorane (black) 10% hydroxyethyl cellulose aqueous solution 20//Water 601/ [Dispersion-[3] 3.3'-dichlorophenylthiourea 155 parts Calcilla carbonate 1 5 n Polyvinyl Alcohol (10% aqueous solution) 20II Water 6
0u [Dispersion-〇] 3-diethylamino-7-chloro 20 parts Fluorane
(Red) 10% hydroxyethylcellulose aqueous solution 201! Water 60 [Dispersion - 1] Bisphenol A 15 parts Stearamide 1OI1 10% hydroxyethylcellulose aqueous solution 5II Calcium carbonate 1O! ! 70 parts or more of water 10 parts of dispersion A prepared as above, dispersion B2O
1 part and 30 parts of water were mixed and stirred to obtain a thermosensitive color forming liquid for low temperature use. On the other hand, 1 dispersion CIO part, dispersion D3
0 parts and 20 parts of water were mixed and stirred to obtain a thermosensitive coloring liquid for high temperature coloring.

Furthermore, an intermediate layer forming liquid for forming an intermediate layer was prepared at the following ratio.

4.4'-dithiodimorpholine 25 parts 10% polyvinyl alcohol aqueous solution lOI! Water 50// Each liquid prepared in the above manner is approximately "Og/rr"
? On a commercially available high-quality paper, heat-sensitive color forming liquid for high temperature (drying amount: 5.5 g/rrr), intermediate layer forming liquid (drying amount: 2.5 g/rrF), heat-sensitive color forming liquid for low temperature ( A two-color heat-sensitive recording material of the present invention was obtained by sequentially applying and drying a coating amount (dry coating amount of 1.0 g/rrf).

Example 2 A two-color heat-sensitive recording material of the present invention was prepared in the same manner as in Example 1 except that 3,3'-dichlorophenylthiourea in the dispersion of Example 1 was replaced with 3,3'-difluorophenylthiourea. I got it.

Comparative Example J All the same procedures as Example 1 except that 3,3'-dichlorophenylthiourea in the dispersion solution of Example J was replaced with bisphenol A.
A comparative two-color heat-sensitive recording material was obtained in the same manner as described above.

Comparative Example 2 3-dibutylamino- in the low-temperature color forming layer forming solution of Example 1
7-lyloloanilinofluorane is converted into 3-(N-methyl-
A comparative two-color heat-sensitive recording material was obtained in the same manner as in Example 1 except that N-cyclohexylamino)-6-methyl-7-anilite fluorane was used.

The two-color thermal recording paper obtained as described above was measured using a thermal inclinometer with a built-in thermal head (manufactured by Toyo Seiki Co., Ltd.) at a head temperature of 70 to 150°C, a pressing time of 1 second, and a pressing pressure of 2 kg.
/ CIl? Printing was carried out under these conditions, and the color tone, color separation, etc. of the low-temperature and high-temperature colored images were tested. Test results, Comparative Examples 1 and 2
In the sample, the low temperature color image did not disappear when the high temperature color was developed, resulting in an unclear image with mixed color tones. On the other hand, Example 1
, 2, the low-temperature colored image faded during high-temperature coloring, and
It was a clear two-color image with good color separation.

Patent applicant Rico Co., Ltd. Representative Patent Attorney Toshiaki Ikeura

Claims (1)

[Claims] (1) Support] Second, a high-temperature coloring layer, an intermediate layer containing a decoloring agent, and a low-temperature coloring layer are laminated in this order, and the high-temperature coloring layer contains a leuco dye and a phenolic compound. The intermediate layer contains a decolorizing agent represented by the following general formula (A), and the low-temperature coloring layer contains a leuco dye represented by the following general formula (+3) and a thiourea represented by the following general formula (C). A two-color heat-sensitive recording material characterized by containing a derivative. General formula (C) d General formula (B): 1 (wherein, R1 and R2 are alkyl groups having 1 to 4 carbon atoms, R
'' is chlorine or fluorine.) General formula (C): (In the formula, l+' and I+5 are hydrogen, halogen, trifluoromethyl group, or alkyl group having 1 to 4 carbon atoms.)