JPS59146892A - Two-color thermal recording material - Google Patents

Abstract

PURPOSE:To provide a two-color thermal recording material capable of forming a two-color image with a clear tone, wherein a leuco dye and an organic acidic substance are used in a low-temperature thermal color forming layer as a color forming system, and ammonium thiocyanate is used as a decolorizing agent for the color forming layer. CONSTITUTION:A high-temperature thermal color forming layer 2 and a low- temperature thermal color forming layer 3 comprising a color forming system consisting of a basic leuco dye (e.g., 3-cyclohexylamino-6-chlorofluoran) 31 and an organic acidic substance (e.g., 3,5-xylenol) 32 which layers can form colors of different tones at different temperatures are provided on a base (e.g., a paper) 1, wherein ammonium thiocyanate is incorporated in the low-temperature thermal color forming layer as a decolorizing agent 4' at such a position that the agent 4' can display a decolorizing action on the color forming system, to obtain the objective two-color thermal recording material.

Description

DETAILED DESCRIPTION OF THE INVENTION Technical Field The present invention relates to a heat-sensitive recording material, and more specifically, a high-temperature heat-sensitive coloring layer and a low-temperature heat-sensitive coloring layer that develop colors in different tones at different temperatures, respectively, on a support. This invention relates to a two-color heat-sensitive recording material in which a layer is formed.

Conventional thermal recording methods have advantages over other recording methods, such as not generating noise and not requiring processes such as development and fixing, and have been applied to a variety of recording applications. Along with this, the required performance and quality have also become more diverse. Specifically, high sensitivity, image stability, multicolor recording, etc. can be mentioned, and since multicolor recording in particular has a wide range of applications, a large number of recording + 1 materials have been researched and proposed to date.

Conventional two-color recording materials can be broadly classified into the following two types. The first method is to color only the low-temperature thermosensitive coloring layer during low-temperature heating, and to obtain a mixture of the low-temperature thermosensitive coloring layer and the high-temperature thermosensitive coloring layer during high-temperature heating. This is a method of obtaining the color tone of only the high-temperature heat-sensitive color-forming layer during high-temperature heating by using a coloring agent that has a decoloring effect on the low-temperature color-forming system.

However, since the first method has drawbacks such as the image produced by color mixture being unclear and bleeding, the second method is generally suitable as a two-color image forming method. Various coloring agents are used in the second two-color heat-sensitive recording material. I can list things that are irritating.

(1) Alkylene oxide adduct of bisphenols (JP-A-54-139741) where A is methylene or alkylidene (2) Ethylene oxide adduct of terephthalic acid (JP-A-55-25306) (3) Long chain 1.2-Glycol (JP-A-55-27217) HOI-1 Here, R is an alkyl group (71) glycerin fatty acid ester (JP-A-55-113593) (5) Urea derivative (JP-A-55-113593) 139290) (6) Algylene oxide adduct of linear glycol (JP-A-55-152094) 0 (Crn H2m O) n H where [( is an alkyl group).

(7) Morpholine derivatives (Japanese Patent Publication No. 56-40588) (8) Solid alcohols (Japanese Patent Publication No. 50-17865) (9) Polyether or polyethylene glycol derivatives (Japanese Patent Publication No. 50-17867 and Japanese Patent Publication No. 50-178)
(10) Nitrogen-containing crystalline organic compounds (Japanese Patent Publication No. 51-19991) (11) Guanidine derivatives (Japanese Patent Publication No. 51-29024) (12) Amine or quaternary ammonium salt (Japanese Patent Publication No. 51-1999)
(No.-1804.8) However, these conventional emulsifying agents are not necessarily satisfactory and cannot sufficiently prevent color mixing and bleeding.

Purpose The purpose of the present invention is to solve the following problems by studying various decolorizing agents.
To provide a two-color heat-sensitive recording material capable of forming two-color images with clear tones without color mixing or bleeding.

Composition As a result of intensive studies in view of the above-mentioned object of the present invention, we have found that in a two-color thermosensitive recording material that uses a leuco dye and an organic acidic substance as a coloring system at least in the low-temperature thermochromic layer, the low-temperature thermochromic layer is emulsified. It has been found that the use of ammonium thiocyanate as the agent solves the above-mentioned conventional drawbacks and achieves the objects of the present invention.

That is, in the present invention, a high-temperature thermosensitive coloring layer and a low-temperature thermosensitive coloring layer, each of which develops different colors at different temperatures, are stacked on a support, and at least the low-temperature thermosensitive coloring layer of the two thermosensitive coloring layers is formed. In a two-color thermosensitive recording material containing a coloring system consisting of a basic leuco dye and an organic acidic substance,
The gist of the present invention is a two-color heat-sensitive recording material characterized by containing ammonium thiocyanate at a position where it can act as a coloring agent for the coloring system of the low-temperature heat-sensitive coloring layer.

The decoloring agent in the present invention, that is, ammonium thiocyanate, has a coloring effect on the coloring system consisting of a leuco dye and an organic acidic substance. Therefore, at least the coloring system in the low-temperature thermosensitive coloring layer is composed of a leuco dye and an organic acidic substance. It must consist of an organic acidic substance.

Examples of the leuco dye used in the present invention include the following substances.

6-(1) Leuco base of triphenylmethane dye 1 ~ In the formula, Rx, RV and Rz are hydrogen, hydroxyl group, halogen, alkyl group, nitro group, amine group, dialkylamino group, monoalkyl group, allyl group be.

Specific examples of the above compounds are as follows.

3.3-bis(p-dimethylaminophenyl) phthalide, 3.3-bis(p-dimethylaminophenyl)-6-cynotylaminophthalide, 3.3-bis(p-dimethylaminophenyl)-6- Dimethylaminophenyl, 3.3-bis(p-dimethylaminophenyl)-〇-chlorophthalide, 3.3-bis(p-dibutylamino, nophenyl)phthalylide (2) Leuco base of fluoran dyes in general In the compound represented by the formula, RX, RV and Rz are the same as in (1) above.

Specific examples of the above compounds are as follows.

3-cyclohexylamino-6-chlorofluorane, 3-(N,N-diethylamino)-5-methyl-7-(
N,N-diethylamino)fluorane, 3-dimethylamino-5,7-cynotylfluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6- Methyl-7-chlorofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- (N-(3=-1-lifluoromethylphenyl)
amine)-6-dinithylaminofluorane, 213.6-bis(diethylamino)mono-(0-chloroanilino)xanthylbenzoic acid lactam) (X4)n 9, where R+j; and R2 are hydrogen, lower It represents an alkyl group, a substituted or unsubstituted phenyl group, a cyanoethyl group, a β-hydroxyethyl group, or a β-halogenated ethyl group, or when R+ and R2 are combined, +Cl-12→-4, +
0 day 2→-5 or (-CH2-)20+cH2+2, R3 and R4 represent hydrogen, lower alkyl group, aralkyl group, amino group or phenyl group, R3
Any one of and R4 is hydrogen, ×1, ×2 and ×
3 represents hydrogen, a lower alkyl group, a lower alkoxyl group, a halogen atom, a halogenated methyl group, a nitro group, an amino group, or a substituted amine group; x4 represents hydrogen, a halogen, a lower alkyl group, or a lower alkoxyl group; , n represents O or an integer from 1 to 4.

Specific examples of the above compounds are as follows.

3-(2'-hydroxy-4''-dimethylaminophenyl)-3-(2=-methoxy-5'-chlorophenyl)
Phthalide, 3-(2=-hydroxy-4'''-dimedyla=10-minophenyl)-3-(2--mer~xy5--2]
-Lophenyl)phthalide, 3-(2”-hydroxy-4-diedylaminophenyl)-3-(2”-methoxy-5′-methylphenyl)
Phthalide, 3-(2--Me1-4-dimethylaminophenyl)-3-(2'--Hydroxy-4-1chloro-5-
-Methylphenyl) phthalide Examples of organic acidic substances that can develop color by reacting with these leuco dyes under heat include the following substances.

3.5-xylenol, methyl-4-hydroxybenzoate, thymol, 4-hydroxyacetophenone, p
-tert-butylphenol, α-naphthol, 4
-Hydroxyphenoxide, β-naphthol, catechol, resorcinol, hydroquinone, 4-tert-octylcatechol, 4,4''-5ea-butylidenephenol, 2,2-dihydroxydiphenyl, 2,2-
-methylenebis(4-medy-6-tert-butylphenol), 2,2'-bis(4-hydroxyphenyl)propane, 4,4'-isopropylidene-bis(
2-tert-butylphenol, 4.4--5ec
-Butylidene diphenol, pyrogallol, phloroglucin, phloroglucinol, succinic acid, benzoic acid, maleic acid, stearic acid, tartaric acid, gallic acid, citric acid, salicylic acid, 1-hydroxy-2-naph 1 to 1
acid, 〇-hydroxybenzoic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid benzyl ester, p-hydroxybenzoic acid IIo-chlorobenzyl, m-hydroxyaniline arylamide, 2-hydroxy-1') -
On the other hand, since the high-temperature heat-sensitive coloring layer does not need to be decolored, a conventionally known coloring system can be used. An example is given below.

(1) Combination of long-chain aliphatic iron salts such as ferric stearate and ferric myristylate acid with phenols such as tannic acid, gallic acid, and ammonium salicylate.

(2) Combinations of heavy metals and sulfates, such as silver, lead, mercury, and thorium sulfates, with sulfur compounds, such as Na-terithionate, sodium diosulfate, and thiourea.

(3) Combinations of noble metal salts of organic acids such as silver behenate and silver stearate with aromatic organic reducing agents such as protocatechuic acid, spiroindane, and hydroquinone; (4) Lead caproate, lead pelargonic acid, and behenate. A combination of an organic acid lead salt such as acid lead and a thiourea derivative such as ethylenethiourea or N-dodecylthiourea.

Furthermore, in the high temperature thermosensitive coloring layer, if the tone and coloring temperature of the low temperature thermosensitive coloring image are taken into consideration, leuco dyes and organic acidic substances can also be used as the coloring system in the same way as in the low temperature thermosensitive coloring layer.

Further, in order to form each heat-sensitive coloring layer and the coloring agent layer, the following polymeric compounds are used as a binder.

Polyvinyl alcohol, me-1-xycellulose, hydroxyethylcellulose, carboxymethylcellulose,
Polyvinylpyrrolidone, polyacrylamide, polyacrylic acid, starch, gelatin, polystyrene, vinyl chloride-vinyl acetate copolymer, polybutyl methacrylate,
Polyvinyl chloride, styrene-butadiene copolymer, chlorinated rubber Next, an example of the structure of the two-color heat-sensitive recording material of the present invention will be explained with reference to the drawings. 1 to 3 show examples of the structure of the two-color heat-sensitive recording material of the present invention. In the figures, 1 is a support such as paper, film, synthetic paper, etc.; 2 and 3 are a high-temperature heat-sensitive coloring layer, and a low-temperature heat-sensitive layer, respectively. It is a coloring layer. In addition, 31 is a leuco dye, 3
2 represents a 1a acidic substance, and 4″ represents a coloring agent.

Fig. 1 shows a structure in which a decoloring agent 4' is dispersed in a low temperature thermosensitive coloring layer 3, and Fig. 2 shows a structure in which a Urairo layer 4 is provided between a high temperature thermosensitive coloring layer 2 and a low temperature thermosensitive coloring layer 3. show. FIG. 3 shows a structure in which the low-humidity heat-sensitive coloring layer 14-3 is composed of two layers: a layer containing a lubricant 4- and an organic acidic substance 32, and a layer containing a leuco dye 31.

Ammonium thiocyanate, which is the color erasing agent of the present invention, is used in an amount of 2 to 10 times the combined weight of the leuco dye and organic acidic substance in the low-temperature heat-sensitive coloring layer.

Examples of the present invention will be shown below.

Example 1 Solutions A, B, and C were prepared by dispersing a mixed solution having the following composition for 500 hours using a ball mill.

Solution A: 3.3-bis(p-dimethylamino)-6-sinothylaminofluorane 10% by weight 20% polyvinyl alcohol aqueous solution 07I Water
70 Solution B: 2-chloro-3-methyl-6-diedylaminofluorane 20% polyvinyl alcohol aqueous solution 10 Water
70 lnoC solution; Bisphenol A 20M amount% 20% polyvinyl alcohol aqueous solution 10〃 Water
70 Also, a solution D having the following composition was prepared as a decolorizing agent solution.

Solution D: Ammonium thiocyanate 20% by weight water
80
Further, a liquid mixture having the following composition was dispersed in an attritor for 2 hours to prepare liquid E.

E Liquid Nistearamide 20% by weight 5% methylcellulose aqueous solution 40 Nonionic surfactant
1. Water
Δ, B, C, D of 3911 or more
Using Solution E and a 20% aqueous polyvinyl alcohol solution, each color forming layer liquid and decoloring layer liquid with the composition shown in Table 1 were prepared, and a high temperature thermosensitive coloring layer, an embossing layer, and a low temperature thermosensitive layer were coated on commercially available high-quality paper with a basis weight of 55 a/m2. The color-forming layers were coated and formed in this order to produce a two-color heat-sensitive recording material of the present invention.

17- Table 1 High temperature liquid D 10 Heat sensitive liquid C 50 507m? Coloring layer PVA aqueous solution 20 Water 20 D liquid 55 Coloring layer PVA aqueous solution 20 51] 7m 2 Water 25 A liquid 8 Low temperature C liquid 40 Heat sensitive E liquid 8 2 Q 7m 2 Coloring layer PVA aqueous solution 10 Water 34 In this way, 1q2 Approximately 95 degrees C
When printed at a temperature of about 145° C., the color changed to blue, and when printed at a temperature of about 145° C., a clear red color was obtained.

18- There was no color mixing in any of the colored images, no low-temperature colored images remained especially in the peripheral areas of the high-temperature colored images, and the images were extremely clear without bleeding.

Example 2 Solutions F and G were prepared by dispersing a mixture having the following composition for 50 hours using a ball mill.

Liquid F: 3-diethylamino-7-o-chloroanilinofluorane 10% by weight 20% polyvinyl alcohol aqueous solution 10 Water
70! lG solution: 3-diethylamino-7-lylorfluorane 20% by weight 20% polyvinyl alcohol aqueous solution 10〃 Water 7
0II Above F and G solutions and C2D prepared in Example 1
, prepare solutions for each coloring layer as shown in Table 2 using Solution E,
A two-color thermosensitive recording material of the present invention was prepared in the same manner as in Example 1.

Table 2 High temperature E liquid 10 Heat sensitive G liquid 50 5o/m2 coloring layer
PVA water solution 1 20 Water 20 G liquid 4 Low temperature G liquid 20 Heat sensitive E liquid 4 7g/m2 coloring layer D
Liquid 27 PVA aqueous solution 15 Water 30 When the two-color heat-sensitive recording material obtained in this manner was printed at a temperature of about 95°C using a Zaful printer in the same manner as in Example 1, the color changed to red, and then about 140
When printed at a temperature of °C, a clear black color was obtained. Moreover, the colored image was extremely clear without color mixture or bleeding.

Comparative Example Conventionally known lubricants include mericyl alcohol (Japanese Patent Publication No. 17865, 1983), ace1-amide (Japanese Patent Publication No. 50-17865),
1-19991), 1,3-diphenylguanidine (
An emulsion liquid was prepared by dispersing a liquid mixture having the following composition using a ball mill for 50 hours using JP-B No. 51-29024) and stearylamine (JP-A No. 50-18048).

Liquid D: Each of the above lubricants 20% by weight 20% polyvinyl alcohol aqueous solution 10 Water
70 8 Using liquid D' instead of liquid D in Table 1,
A two-color heat-sensitive recording material prepared in the same manner as in Example 1 was used as a comparative example of the two-color heat-sensitive recording material according to the present invention, and printed in the same manner as in Example 1 to evaluate the 21-color image. When using any of the above color erasing agents, a low temperature colored image remains in the periphery of a high temperature colored image, or the colored image suffers from color mixing and lacks sharpness.

Effects As described above, the two-color heat-sensitive recording material of the present invention can form clear two-color recorded images without color mixing or bleeding by using ammonium thiocyanate as a coloring agent.

[Brief explanation of the drawing]

1 to 3 are cross-sectional views showing examples of the structure of the two-color heat-sensitive recording material of the present invention. 1... Support 2... High temperature thermosensitive coloring layer 3... Low temperature thermosensitive coloring layer 4... Decoloring layer 31... Leuco dye 32...Organic acidic substance 4-...Discoloration agent patent applicant Ri Co., Ltd.]- Agent Patent attorney Hidetake Komatsu 22-

Claims (1)

[Claims] A high-temperature thermosensitive coloring layer and a low-temperature thermosensitive coloring layer, each of which develops a different color tone at different temperatures, are stacked on the support, and at least of the two thermosensitive coloring layers, at least the low-temperature thermosensitive coloring layer contains a basic leuco dye. A two-color heat-sensitive recording material containing a color-forming system consisting of a tRM substance and a tRM-bearing substance, characterized in that ammonium thiocyanate is contained in a position capable of decoloring the color-forming system of the low-temperature heat-sensitive coloring layer. do 2
Color thermosensitive recording material.