JPS5922793A - Heat sensitive recording material - Google Patents

Abstract

PURPOSE:To provide a heat sensitive recording material recording a sharp image with high density in low heat energy and free from the adhesion of scum and sticking, obtained by containing a specific oxynaphthoenic ester compound in a heat sensitive color forming layer as a sensitizer. CONSTITUTION:In a heat sensitive color forming layer containing a colorless or a light colored basic dye (e.g., 3-cyclohexyl-methylamino-6-methyl-7-anilinofluorane) and an org. acid and/or a phenolic substance (e.g., bisphenol A) as heat sensitive color forming components in combination, a compound shown by a formula I of a formula II [wherein R is (substituted) alkyl, (substituted) phenyl or (substituted) ethylene] (e.g., 3-oxy-l-naphthoenic methyl ester) is further contained as a sensitizer to obtain an objective heat sensitive recording material. EFFECT:The titled material is excellent in long-term preservability and high in heat sensitivity.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improved heat-sensitive recording material that uses a colorless or light-colored leuco dye and an organic acid and/or phenolic substance that causes the leuco dye to develop color when heated.

2. Description of the Related Art Various heat-sensitive recording materials have heretofore been known in which a heat-sensitive coloring layer is provided on a support such as paper, synthetic paper, or resin film, and is capable of recording an image by developing color by heating. Compared to other recording materials, this material does not require complicated processes such as developing and fixing, can produce records in a relatively short time, does not generate noise, and is low in cost. It is widely used as a recording material for output printers, facsimiles, telex machines, various information devices, medical devices, various measuring devices, automatic ticket vending machines, etc.

However, these conventional recording materials have several drawbacks and have not yet been satisfactory. In particular, there is a strong demand for higher speed output machines, and there are no machines that have sufficient thermal sensitivity to meet this demand. For this reason,
The addition of various sensitizers has been proposed. For example, JP-A-53-39139, JP-A-53-26139
No., JP-A-53-5636, JP-A-53-11036
There are various waxes, fatty acid amides, alkylated biphenyls, substituted biphenyls, alkanes, coumarin compounds, diphenylamines, etc. Furthermore, surface treatments have been applied to increase the smoothness of the heat-sensitive layer to increase heat sensitivity, but the effect has been insufficient. Furthermore, it melts due to heating during recording and adheres to thermal heads, etc., causing scum adhesion and staining development, which significantly impedes running performance and image clarity, so further solutions are needed. Highly desired.

The purpose of the present invention is to solve the above-mentioned conventional drawbacks,
In particular, it is possible to record high-density, clear colored images with low thermal energy, and it does not impede the running performance of the thermal head due to scum cultivation, stalking, etc., and has excellent long-term storage stability. An object of the present invention is to provide a heat-sensitive recording material having an extremely high heat sensitivity.

As a result of repeated research aimed at the object of the present invention, a thermosensitive recording material having a thermosensitive coloring layer containing a colorless or light-colored leuco dye and an organic acid or phenolic substance that causes the leuco dye to develop color when heated, the thermosensitive coloring layer It has been found that the above-mentioned conventional drawbacks can be significantly solved by incorporating a compound represented by the following structural formula, and the present invention has been achieved.

Examples of such compounds with the general formula include (1) 2-oxy-1-naphthoic acid methyl ester (m
, p Near 6°C) (2) 3-Oki7- 〃 〃(m, p:
91-92°C) (3) 4-oxy- (m, p: 178°C) (4) 5-oxy- (m, p: 130-131°C) (5) 6-oxy- 1-naphthoic acid methyl ester (m
, p: 112-113°C) (6) 7-oxy-〃 (m, p: 124-+26°C) (7) 2-oxy-1-naphthoic acid ethyl ester (m, p: s5° C
) (8) 4-oxy-〃 〃 (m, p: 134°C) (9) 5-oxy-〃 〃 (m, p near 3°C) 00) 6-oxy-〃 〃 (m, p: 105~] (17°C) (1υ1-oxy-2-naphthoic acid methyl nyester (m, pnia 8°
C) a7J 3-oxy-〃 (m, p near 5-76°C) 0 row 8-oxy-〃 (m, p: 1.51-152.5°C) Q411
-oxy-2-naphthoic acid ethyl ester (m, p: 4
9℃) (1513-oxy-2-naphthoic acid ethyl ester (
m, p: 85°C) (I[i) 5-oxy-〃 (m, p: 1
50-151°C) θη6-oxy-〃 〃 (m, p: 1] 1~I l 2°C) 0Q8-
Oxy-〃〃 (m, p: l 35-137 °C) 091-oxy-〃 phenyl ester (m, p: 96-98 °G
) (2+12-oxy-3-naphthoic acid phenyl ester (m, p: 12'l-132°C)), but is not limited thereto.

Since the above-mentioned compound exhibits an extremely large effect on the thermal sensitivity of the thermosensitive recording material, it can provide a colored image with high density with lower thermal energy than in the past. Furthermore, since the coloring start temperature shows a sharp rise in the coloring temperature-coloring density characteristic curve, a clear image with high density can be quickly obtained without coloring the surrounding areas of the colored image. Furthermore, the compound used in the present invention is less likely to cause residue adhesion or sticking during dark recording, thereby impairing the running performance of the thermal head, and can withstand long-term recording.

In the present invention, conventionally known leuco dyes, organic acids, or phenolic substances constituting the heat-sensitive coloring layer are used, and examples thereof are shown below.

Examples of leuco dyes include triphenylmethane phthalide series, fluoran series, phenothiazine series, indolyl phthalide series, spiropyran series, leuco auramine series, rhodamine lactam series, triphenylmethane series, triazene series, naphtholactam series, and subiro Notaranxanthene series,
It is a substance selected from the group of azomethine series, benzobylane series, hydroxyphthalane series, leukoolamine series, etc. Organic acids include stearic acid, oxalic acid, maleic acid, tartaric acid, citric acid, benzoic acid, naphthoate, etc. acid,
4-t-butylphenol, 4-phenylphenol,
Solid organic acids such as 2.2'-dihydroxydiphenyl, 4.4'-isogropyritene diphenol, naphthol, 4-hydroxyamotophenone, methyl-4-hydroxybenzoate, and salicylic acid, or acidic combinations thereof with formalin. Polymer, phenol-aldehyde polymer, phenol-acetylene polymer, rosin-modified maleic acid resin, styrene-maleic anhydride copolymer hydrolyzate, carboxypolyethylene polymer hydrolyzate, vinyl ethyl ether-maleic anhydride copolymer The substance is selected from the group of a combined hydrolyzate, an ethylene-maleic anhydride copolymer hydrolyzate, and the like.

This will be explained below using examples.

Examples and Comparative Examples Mixtures having the following compositions were dispersed for 24 hours using a ball mill, and equal parts by weight were mixed to prepare a thermosensitive coloring layer forming solution.

Solution A and Solution B. Wax solution C, which is a conventional sensitizer, is prepared in the following manner.

Liquid E or liquid D-F having the following composition is prepared in place of the liquid E and used in the recording material forming liquid of the present invention.

Solution D, Solution E, Solution F Example 1 A coating solution prepared by mixing equal weights of Solutions A, B, and D was applied to the surface of high-quality paper using a wire bar to a coating weight of 611/n after drying. Thermal paper was prepared by coating and drying to give the following properties.

Example 2: Equal weights of liquid A, liquid B, and liquid E were mixed, and the same weight as that of Example 1 was prepared. I did the same thing.

Example 3 - Equal weights of liquid A, liquid B, and liquid F were mixed, and Example 1. I did the same thing.

Comparative example 1゜ Example 1 was prepared by mixing equal weights of liquid A and liquid B. I did the same thing.

Comparative Example 2: Equal weights of liquid A, liquid B, and liquid E were mixed, and Example 1. Same as Nishida.

The temperature coefficient γ value of the color density curve due to heating of the thermal paper produced above is shown in the table. The color density is a function of the color temperature T, and there is a linear relationship between the color density and the temperature between the color development start temperature and the temperature at which the color density is almost saturated. The temperature coefficient (γ value) of this color density is defined by the slope (αD/.T) of the straight line with respect to the temperature axis. From the table, Example 1.23,
It shows a higher concentration rise than Comparative Example 1.2,
It can be seen that the thermal sensitivity of the thermosensitive layer is significantly improved.

Furthermore, when the heat-sensitive recording material obtained in this way was printed on a thermal printer with a built-in thermal head, a black image with high density was obtained.
Comparative example 1.2 with almost no subnoking phenomenon observed.
It was recognized that the running performance was better.

Patent Applicant: Tomoekawa Paper Mills Co., Ltd. Procedures Amendment Written by Kazuo Wakasugi, Commissioner of the Patent Office, Date of Salary February 1982, 1, Indication of the Case, Patent Application No. 131157, 1982, 2, Name of the Invention: Thermal Recording Material, Material 3. Relationship with the case of the person making the amendment Patent applicant telephone: 272-4111 (Humanity) 4. Date of amendment order Voluntary amendment 5. No increase in the number of inventions due to the amendment 6. Column 7 of "Detailed Description", Contents of the amendment 1) Page 4, line 11, next to the formula "(wherein R is a substituted or unsubstituted alkyl group, a phenyl group, a substituted phenyl group, a substituted or unsubstituted Indicates ethylene group.

)” is inserted.

2) On page 8, lines 15 and 16, ``Mix equal parts by weight after preparation'' is corrected to ``Mix after preparation.''

3) Page 9, lines 2 to 4 “Bisphenol A 20 parts Polyvinyl alcohol (10% aqueous solution) 30 parts water
50 copies” will be corrected as follows.

"Bisphenol A 14 parts Polyvinyl alcohol (10% aqueous solution) 33 parts Calcium carbonate 20 parts Water
33 copies" 4) Page 10, line 6, "Mix liquids A, B, and D in equal weights.''
0 parts, 30 parts of liquid B, 20 parts of liquid D, and 10 parts of polyvinyl alcohol (10% aqueous solution).''

5) On page 10, line 11, change "mix equal weights of liquid A, liquid B, and liquid E" to "A
0 parts, 30 parts of liquid B, 20 parts of liquid E, and 10 parts of polyvinyl alcohol (10% aqueous solution).''

6) Page 10, line 14 [mixing equal weights of liquids A, B, and F 17] was changed to ``10 parts of liquid A, 30 parts of liquid B, 20 parts of liquid F, and 110 parts of polyvinyl alcohol (10% aqueous solution). ``mix it up'' and correct it.

7) Page 1 O, line 17, ``Mix liquids A and B in equal weight,'' with 1AAlO2, 30 parts of liquid B, and 10 parts of polyvinyl alcohol (10% aqueous solution).
8) On the first line from the bottom of page 10, "Mix liquids A, B, and C in equal weights," to "1 part of liquid A."
0 parts, 30 parts of liquid B, 20 parts of liquid C, and 10 parts of polyvinyl alcohol (10φ aqueous solution) are mixed.''

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Claims (1)

[Scope of Claims] A heat-sensitive recording material having a heat-sensitive coloring layer containing a combination of a colorless or light-colored basic dye, an organic acid and/or a phenolic substance as a heat-sensitive coloring component, wherein the coloring layer has the following general formula: A heat-sensitive recording material characterized by containing the compound shown below. General formula (wherein R is a substituted or unsubstituted alkyl group, a phenyl group,
Indicates a substituted phenyl group, a substituted or unsubstituted ethylene group. )