JPS6195979A - Dichroic thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a dichroic thermal recording material having improved color separability and excellent water resistance by a method in which the three layers, a high-temperature color-forming layer, an intermediate layer containing a defoaming agent, and a low-temperature color-forming layer, are laminated order on a supporter, and a protective layer is provided on the low- temperature color-forming layer. CONSTITUTION:A high-temperature color-forming layer contains a leuco dye and a phenolic compound. An intermediate layer contains a defoaming agent as represented by the general formula (A). A low-temperature color-forming layer contains a leuco dye and a thiourea derivative as represented by the general formula (B), where R<1> and R<2> are each a C1-C4 alkyl and R<3> is Cl or F. A protective layer contains a Si-modified polyvinyl alcohol as main component and acetylene alcohol as an auxiliary component. The Si-modified polyvinyl alcohol has a polymerization degree of 500-8,000 and a saponification degree of 70-100% and the amount of Si to be contained per monomer is 0.05-5mol%. The amount of the acetylene alcohol to be used is 0.01-20wt% on the basis of Si-modified polyvinyl alcohol in the protective 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 include a colorless or light-colored leuco dye (color-forming main agent) having a lactone ring, lactam ring, spiropyran ring, etc. in the heat-sensitive coloring layer, and a color developer that develops color by reacting with this leuco dye when heated. Agent (color development aid)
Heat-sensitive recording materials are often used because they have clear color tones and less fogging. By the way, heat-sensitive recording materials are used for copying books, documents, etc. because they can easily produce colored images just by heating. In addition to being used for recording various types of information such as electronic computers, facsimiles, and telex, and for recording the output of measuring instruments, it is also used to display and display particularly necessary data and numbers more clearly depending on the purpose of recording. Naturally, it is desirable to be able to record the color (display color) of that part differently from the color of other parts.

Recently, attempts have been made to obtain multicolor recording by utilizing differences in heating temperature or thermal energy, and various multicolor thermosensitive recording papers have been proposed accordingly. 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 of them is that when coloring the high temperature coloring layer, the color is mixed with the color tone of the low temperature coloring layer to obtain a color tone different from that of the low temperature coloring layer.

The other method is to use a decoloring agent that decolorizes the low-temperature color-forming layer when coloring the high-temperature color-forming layer to obtain only the color tone of the high-temperature color-forming layer without color mixing of the color tone of the low-temperature color-forming layer. As a specific example of these, the former is
Publication number, Special Publication No. 49-4342, Special Publication No. 49-277
No. 08, JP-A-48-86543, JP-A-Sho 49
-65239, etc., and the latter is
Special Publication No. 50-17865, Special Publication No. 50-1786
Publication No. 6, Special Publication No. 51-29024, Special Publication No. 1977
-87542 publication, JP-A-50-18048 publication,
These are disclosed in Japanese Patent Laid-Open No. 53-47843 and the like.

However, in the case of the former multicolor thermosensitive recording paper,
During high-temperature coloring, the color tone is specifically realized to mix with the color tone of the low-temperature coloring layer, and the disadvantage is that the high-temperature coloring tone is limited to black threads with strong strength, such as red-black, blue-black, etc. There is. On the other hand, in the case of the latter multicolor thermosensitive recording paper,
Although the combination of color tones can be freely selected, higher aliphatic alcohols, polyethers, polyethylene glycol derivatives, and acetamide and stearamide as nitrogen-containing organic compounds are used as decolorizing agents to decolor the low-temperature coloring layer during high-temperature coloring. , phthalonitrile, guanidine derivatives as amine derivatives, etc. have been proposed, but in conventional planting, when coloring at high temperatures, it has a decoloring effect not only on the low-temperature coloring layer but also on the high-temperature coloring layer, causing the color to become unclear. There was a drawback. In addition, in order to improve the disadvantage that the image on the contact area fades when it comes into contact with water for a long time, a polymeric protective layer may be provided on the surface of the heat-sensitive coloring layer. However, it was still not satisfactory.

〔the purpose〕

An object of the present invention is to provide a leuco-based two-color heat-sensitive recording material with improved one-color separation and excellent water resistance.

〔composition〕

That is, according to the present invention, at least three layers, a high temperature coloring layer, an intermediate layer containing a decolorizing agent, and a low temperature coloring layer, are laminated in this order on a support, and a protective layer is further provided on the low temperature coloring layer. The high temperature color forming layer contains a leuco dye and a phenolic compound, and the intermediate layer contains a decoloring agent represented by the following general formula (A).

The low-temperature coloring layer contains a leuco dye and a thiourea derivative represented by the following general formula (B), and the protective layer contains modified polyvinyl alcohol as a main component and acetylene alcohol as an auxiliary component. A color thermosensitive recording material is provided.

General formula (A): (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 (1) include the following.

Specific examples of the leuco dye represented by the general formula (B) include 3-dibutylamino-7-riloloanilinofluoran, 3-diethylamino-7-chloroanilinofluoran, and 3-dibutylamino-7-chloroanilinofluoran. Examples include 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-m-chlorophenylthiourea, N,N'-di-P-chlorophenylthiourea,
Examples include N,N'-trifluoromethylphenylthiourea and N,N'-methylphenylthiourea.

On the other hand, examples of the color developer to be included in the high-temperature coloring layer include 4-hydroxy phenoxide.

4-tert-butylphenol, 4-hydroxyacetophenone, resorcissi, α-naphthol, thymol, β-naphthol, catechol, hydroquinone.

Pyrogallol, phloroglucin, phloroglucin carboxylic acid, 4,4'-5ec-butylidene diphenol,
4,4'-isopropylidene-bis(2-t,-butylphenol), 4-thi-octylcatechol.

4'-5ec-butylidene diphenol, 2.2'
-dihydroxydiphenyl, 2.2' -methylene-
Bis(4-methyl-6-L-butylphenol), 2
．． Examples include 2-bis(4'-oxyphenyl)propane (also known as bisphenol A) and 3,5-xylenol.

In the present invention, the leuco dyes used in the high-temperature coloring layer 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 may be arbitrarily applied. .

Leuco compounds of triphenylmethane-based, fluoran-based, phenothiazine-based, auramine-based, spiropyran-based, and indolinophthalide-based dyes are preferably used. Specific examples of such leuco dyes include 3-diethylamino-7-chlorofluoran, 3-diethylamino-6-methyl-7-chlorofluoran, and 3-cyclohexylamino-6-chlorofluoran.

Examples include 3-diethylaminobenzo[α]fluoran.

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. For example, polyvinyl alcohol, starch and its derivatives, methoxy cellulose, hydroxy Ethyl cellulose.

Cellulose derivatives such as carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acryl amide/acrylic ester/methacrylic acid ternary copolymer, styrene/maleic anhydride Acid copolymer alkali salt, isobutylene-maleic anhydride copolymer alkali salt, polyacrylamide,
In addition to water-soluble polymers such as sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, and methyl.

latex such as ethylene/butadiene copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. 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. , urine;)3-
Organic fine powders such as formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin can be mentioned, and examples of thermofusible substances include higher fatty acids or their esters, amides, or metal salts, as well as various Waxes, condensates of aromatic carboxylic acids and amines, Yasu JJ, hexaacid phenyl esters, higher linear glycols, dialkyl 3,4-epoxy-hexahydrophthalates, higher ketones,
Examples include other thermofusible organic compounds having a melting point of about 50 to 200°C.

In the present invention, in order to improve image stability, a protective layer is provided on the low-temperature coloring layer, and this protection layer! It is characterized in that the L layer contains modified polyvinyl alcohol containing silicon in one molecule as a main component, and further contains acetylene alcohol as an auxiliary component.

In this case, the silicon-modified polyvinyl alcohol containing silicon in its molecule has a degree of polymerization of 500 to 3,000. Saponification degree 70
A silicon content in the range of 100% to 100% is preferably used, and the silicon content is preferably 0.05 to 5 mol% in terms of monomer units.

The acetylene alcohol used in the present invention means a monohydric or polyhydric alcohol having an acetylene group, and includes those represented by the following general formulas (1) and (II).

(In the above formula, R1-R6 represent hydrogen or an alkyl group, and R1-R6 may be the same or different.) Preferred specific examples of the acetylene alcohol include 9
For example, 2,4,7.9-tetramethyl-5-decyne-
4,7-diol, 2,5-dimethyl-3-hexyne-
Examples include 2,5-diol, 3-methyl-1-butyn-3-ol, 3-methyl-1-pentyn-3-ol, and the like. These acetylene alcohols can be used alone or in the form of a mixture of two or more.

In the present invention, the protective layer may contain a filler to improve coating properties and a curing agent to improve coating strength according to conventionally known techniques.

In the present invention, the proportion of acetylene alcohol used is
0 for silicon-modified polyvinyl alcohol in the protective layer
．． The proportion is preferably 0.01 to 20% by weight, preferably 0.2 to 10% by weight. If the proportion of acetylene alcohol used is too low, sufficient image stabilization effect will not be obtained.
If the amount is too large, the protective film forming effect will be impaired and the image stabilizing effect will also be reduced.

The two-color thermosensitive recording material of the present invention can be modified in various ways.1 For example, in order to more completely prevent the influence of the decolorizing effect of the intermediate layer decoloring agent on the high temperature coloring layer during high temperature coloring, the An interlayer, such as a fusible material layer, can be provided between the high temperature coloring layer and the decolorizing agent 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. Further, in the present invention, since a special protective layer is provided, image decoloring due to water is not observed. Therefore, the two-color image formed with the heat-sensitive recording material of the present invention has good color separation, provides a clear image, and is also excellent in water resistance.

〔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 O.

[Dispersion-8] 3-dibutylamino-7-chloroanilinofluorane (
Black) 20 parts 10% hydroxyethyl cellulose aqueous solution 20 water

60 [Dispersion-B] 3.3'-Dichlorophenylthiourea 15 parts Calcium carbonate 5 Polyvinyl alcohol (10% aqueous solution) 20 Water
60 [Dispersion-C] 3-diethylamino-7-chlorofluoran (red) 20 parts 10% hydroxyethylcellulose aqueous solution 20 Water

(>Qn [Dispersion-B] Bisphenol A 15 parts Stearic acid amide 101!10
% and droxyethylcellulose aqueous solution 5n calcium carbonate to water
7Q++
10 parts of dispersion A prepared as above, 40 parts of dispersion B
1 part and 30 parts of water were mixed and stirred to obtain a low temperature thermosensitive color forming liquid. On the other hand, dispersion C10 parts 1 dispersion 030
1 part and 20 parts of water were mixed and stirred.

A thermosensitive color forming liquid for high temperature color development was obtained.

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

[E liquid]

4.4'-dithiodimorpholine 25 parts 1
0% polyvinyl alcohol aqueous solution lQn water
50
Protective layer forming liquid F for forming a protective layer in addition to 1F was prepared at the following ratio.

[F liquid]

Stearin 1 part lead 2 parts calcium carbonate 10 parts water
30 parts or more of each solution prepared in the same manner is weighed approximately 50 g.
/rr? On commercially available high-quality paper, heat-sensitive color forming liquid for high temperature (drying amount: 5.5 g/+rr), intermediate layer forming liquid (drying amount: 2.5 g/+rr), heat-sensitive color forming liquid for low temperature ( dry coating amount 1.0g/rrl'), protective layer forming liquid (
Apply when dry! 1.0 g/rn) was sequentially applied and dried to obtain a two-color heat-sensitive recording material of the present invention.

Example 2 A two-color thermosensitive product of the present invention was produced 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. Obtained recording materials.

Example 3 2,4,7,9-tetramethyl-5-decyne-4,7-diol in the protective layer of Example 1 was replaced with 2,5-dimethyl-3-hexyne-2,5-diol. A two-color heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 except for the following changes.

Comparative Example 1 A comparative two-color thermosensitive recording material was obtained in the same manner as in Example 1 except that 3,3'-dichlorophenylthiourea in Dispersion B of Example 1 was replaced with bisphenol A.

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.

Comparative Example 3 A comparative two-color heat-sensitive recording material was obtained in the same manner as in Example 1, except that the following liquid G was used in place of the protective layer forming liquid E of Example (1).

[G liquid]

Polyvinyl alcohol 10% aqueous solution 10 parts Silica fine powder 0.3 part Water
6
The two-color thermosensitive recording material obtained as described above was tested 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 crimping time of 1 second, and a crimping pressure of 2 kg.
/ Color tone 1 of low-temperature and high-temperature color images printed under ad conditions
Color separation properties, water resistance, etc. were tested. Test results, Comparative Example 1
, 2.3, the low-temperature colored image did not disappear during high-temperature coloring, resulting in an unclear image in which one color tone was mixed, and the colored portion after the water resistance test was severely discolored. In contrast, the samples of Examples 1, 2, and 3.

The low-temperature colored image was discolored during high-temperature coloring, resulting in a clear two-color image with good color separation, and there was almost no discoloration of the colored area after the water resistance test.

Claims (1)

[Claims] (1) Three layers, a high temperature coloring layer, an intermediate layer containing a decolorizing agent, and a low temperature coloring layer, are laminated in this order on a support, and a protective layer is further provided on the low temperature coloring layer, and the high temperature coloring layer is laminated in this order. The layer contains a leuco dye and a phenolic compound, the intermediate layer contains a decoloring agent represented by the following general formula (A), and the low-temperature coloring layer contains a leuco dye represented by the following general formula (B) and a decoloring agent represented by the following general formula (A). (
A two-color heat-sensitive recording material containing a thiourea derivative represented by C), wherein the protective layer contains silicon-modified polyvinyl alcohol as a main component and acetylene alcohol as an auxiliary component. General formula (A): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, X is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, Y is ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲
There are mathematical formulas, chemical formulas, tables, etc. ▼, ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼, R is an alkylene group) ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, Z is ▲ Mathematical formulas, chemical formulas, tables, etc. ▼, higher alkyl group) General formula (B): ▲Mathematical formula, chemical formula, table, etc.▼ (In the formula, R^1 and R^2 are alkyl groups with 1 to 4 carbon atoms, R^3 is chlorine or fluorine.) General formula (C): ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (In the formula, R^4 and R^5 are hydrogen, halogen, trifluoromethyl group, or a group with 1 to 4 carbon atoms. (alkyl group)