JPH03158290A - Thermal recording body - Google Patents

Abstract

PURPOSE:To improve moisture resistance, heat resistance and finger-print resistance by combining two kinds of the specific leuco dyes of an anilinofluoran group in a thermal recording body utilizing the developing reaction of an electron donative dye and a developer. CONSTITUTION:In a thermal recording body in which a colorless or light-colored leuco dye and a developer color-developing by a reaction with the leuco dye on a support, 3-(N-ethyl-N-ethoxypropyl)amino-6-methyl-7-anilinofluoran and 3-(N-ethyl-N-furfuryl)amino-6-methyl-7-anilinofluoran are combined as the leuco dye. Accordingly, shelf stability can be improved without generating trouble such as sticking, the adhesion of a foreign matter onto a thermal head, etc.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a heat-sensitive recording medium, and particularly to a heat-sensitive recording medium that has excellent storage stability of recorded portions at high temperatures and high humidity.

(Prior Art) The thermosensitive recording method, which utilizes a color-forming reaction between an electron-donating dye and a color developer, is a primary color-developing system and does not require a developing and fixing process.

In addition, because it has features such as easy hardware maintenance, it is widely used in recording paper for various printers, Axim IJ, measuring instruments, etc. Recently, with the increase in high-speed recording, recording devices have become lighter and smaller. (1) The color density and color sensitivity must be sufficient for thermal recording paper.

(2) The fastness of the recorded area after color development is sufficient.

(3) It is required that the recording portion after color development has sufficient robustness even if external conditions such as fingerprints or temperature and humidity change.

Conventionally, various methods have been proposed for the purpose of improving the above-mentioned drawbacks of heat-sensitive recording materials, but no satisfactory solution has yet been found. That is, although the addition of various phenol derivatives has been proposed in JP-A-49-45747 and JP-A-49-54040, this method is not sufficiently effective in preventing fading and may cause the skin to become foggy. There were drawbacks such as the color disappearing if a fingerprint was attached to a colored part, and the color developing if a fingerprint was attached to an uncolored part, and there was no product that could be used in practice. Also, JP-A-5
3-17346, JP-A-53-17347, and JP-A-55-34901 propose the addition of various resins, and although some are found to be effective, they have not been used as heat-sensitive recording materials. In this case, new problems such as sticking and adhesion of residue to the thermal head arise.

(Problems to be Solved by the Invention) Therefore, an object of the present invention is to provide a heat-sensitive recording material having excellent moisture resistance, heat resistance, and fingerprint resistance.

(Means for Solving the Problems) The present invention was made based on the knowledge that the above problems can be efficiently solved by using two specific anilinofluorane-based leuco dyes in combination.

That is, the present invention uses 3-(N-ethyl-N-ethoxypropyl)amino-6-methyl-7-anilinofluorane and 3-(N-
Thermal recording material with excellent storage stability without problems such as sticking and adhesion of residue on the thermal head by using ethyl-N-furfuryl) amino-6-methyl-7-anilinofluorane I was able to get

3-(N-ethyl-N-ethoxypropyl)amino-6-methyl-7-anilinofluorane [Compound I] and 3-(N-ethyl-N-furfuryl)amino-6-methyl- used in the present invention 7-anilinofluorane [compound (■)] is represented by the following formulas [I] and [■], respectively.

The total amount of compounds and H used is 1 to 1 of the total solid content of the heat-sensitive recording layer.
40% by weight (hereinafter abbreviated as %), preferably 5 to 20%
%. The ratio (weight ratio) of compounds (1) and (2) used is 99:1 to 1:99, preferably 95:5 to 5:95.
It is. Compounds ■ and ■ are disclosed in JP-A-58-20, respectively.
It can be easily produced by the methods described in JP-A-9589 and JP-A-60-184878.

In the present invention, leuco compounds other than compounds (■) and (■) include:
For example, it is a substance that develops color by reacting with an organic acidic substance,
Examples include various derivatives such as triphenylmethane, triphenylmethanephthalide, fluoran, leucoolamine, diphenylmethane, phenothiazine, phenoxazine, spiropyran, impirin, and indigo. Specifically, crystal violet lactone, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N-ethyl-P-)luidino)-6
-Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-(ortho, para-dimethylanilino)fluorane, 3-piperidino-6°-methyl-7-
Anilinofluorane, 3-(N-cyclohexyl-N-
methylamine)-6-methyl-7-anilinofluorane, 3-diethylamino-7-(ortho-chloroanilino)fluorane, 3-diethylamino-7-(meta-trifluoromethylanilino)fluorane, 3-diethylamino-6 -Methyl-chlorofluorane, 3-diethylamino-6-methyl-fluorane, 3-(N-ynamyl-N-ethylamino)-6-methyl-7-anilinofluorane, 3-dibutylamino-6-methyl- 7-anilinofluorane is mentioned.

These can be used alone or as a mixture of two or more.

When the above-mentioned leuco compounds are used together with Compounds I and H, the weight ratio of the total usage of Compounds I and (2)/other leuco compounds is 99/1 to 80/20, preferably 9515 to 90/1.
It is preferable to set it to 0.

Examples of the color developer include the following substances. For example, activated clay, acid clay, attapulgite, bentonite, colloidal silica, inorganic acidic substances such as aluminum silicate, 4-tert-butylphenol, 4-hydroxydiphenoxide, α-naphthol, β-naphthol, 4-hydroxyacetophenol, -tert-
Octylcatechol, 2,2'-dihydroxydiphenol, 2°2'-methylenebis(4-methyl-6-te
rt-isobutylphenol), 4,4'-isopropylidene bis(2-tert-butylphenol), 4
゜4'-5ec-Butylidene diphenol, 4-phenylphenol, 4.4'-isopropylidene diphenol (bisphenol A), bis(4-hydroxyphenyl) n-butyl acetate, bis(4-hydroxyphenyl) methyl acetate , bis(4-hydroxyphenyl)ethyl acetate Jlz, 2. 2-(2-hydroxyphenyl,
3-hydroxyphenyl)propane, 4-hydroxy-
4'isopropoxydiphenylsulfone, 4,4'-thiobis[6-t-butyl (6-t-butyl-m-cresol)], 2,2'-methylenebis(4-chlorophenol), hydroquinone, 4. Phenolic compounds such as 4'-cyclohexylidene diphenol, benzyl 4-hydroxybenzoate, dimethinobehydroquinone monobenzyl 4-hydroxyphthalate ether, novolac type phenolic resin, phenol polymer, benzoic acid, p
-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-sec-butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid,
3.5-Dimethyl-4-hydroxybenzoic acid, salicylic acid, 3-isopropylsalicylic acid, 3-tert-butylsalicylic acid, 3-benzylsalicylic acid, 3-(α-methylbenzyl)salicylic acid, 3-chloro-5-(α- Aromatic carboxylic acids such as methylbenzyl)salicylic acid, 3,5-di-tert-butylsalicylic acid, 3-phenyl-5-(α,α-dimethylbenzyl)salicylic acid, 3,5-di-α-methylbenzylsalicylic acid, and These phenolic compounds, one or a mixture of two or more organic acidic substances such as salts of aromatic carboxylic acids and polyvalent metals such as zinc, magnesium, aluminum, calcium, titanium, manganese, tin, and nickel. .

In the heat-sensitive recording material of the present invention, the ratio of the leuco dye and color developer in the recording layer is appropriately selected depending on the type of leuco dye and color developer used, and is not particularly limited. For example, generally 1 to 50 parts by weight, preferably about 1 to 10 parts by weight of the color developer is used per 1 part by weight of the leuco dye.

To prepare a coating solution containing these substances, the coloring agent and the coloring agent are generally dispersed together or separately using water as a dispersion medium using a stirring/pulverizing machine such as a ball mill or an attritor sand grinder. It is prepared as In this case, it is desirable that the dispersed particles be as small as possible, specifically, particles of 2 μm or less.

This coating liquid contains starches, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, and adhesives.
Polyvinyl alcohol, diisobutylene, maleic anhydride copolymer salt, styrene, maleic anhydride copolymer salt,
Ethylene, acrylic acid copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion, etc., in an amount of 10 to 40% by weight, preferably 15% of the total solid content
~30% by weight is used.

Furthermore, various auxiliary agents can be added to the coating liquid.
For example, dispersants such as sodium dioctyl sulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, alginates, fatty acid metal salts, ultraviolet absorbers such as benzophenone and triazole, and other antifoaming agents. , fluorescent dyes, colored dyes, and the like.

In addition, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax, and ester wax, kaolin,
Inorganic pigments such as clay, talc, calcium carbonate, calcined clay, titanium oxide, diatomaceous earth, particulate anhydrous silica, activated clay, stearamide, methylene bisamide stearate, oleic acid amide, palmitic acid amide,
It is also possible to add sensitizers such as matcha oleic acid amide, coconut fatty acid amide, metaterphenyl, parabenzyl biphenyl, ester derivatives of hydroxynaphthoic acid, dibenzyl terephthalate, and tribenzylamine.

Further, in the present invention, an intermediate layer may be provided between the support and the heat-sensitive recording layer, or a protective layer may be provided on the heat-sensitive recording layer.

In order to further improve storage stability, for example, phenolic resin,
Hindered phenyl compounds (especially 11.3-)
2-Methyl-4-hydroxy-5-cyclohexylphenol)butane, 1,13-tris(2-methyl-4-
hydroxy-5-tert-butylphenyl)butane)
etc. can be used.

Paper is mainly used as the support for the heat-sensitive recording material of the present invention, but various nonwoven fabrics, plastic films, synthetic papers, metal foils, etc., or composite sheets thereof can also be used as desired.

(Effects of the Invention) According to the present invention, there is provided a heat-sensitive recording medium that does not cause problems such as sticking and adhesion of residue on the heat-sensitive head and has excellent storage stability.

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Liquids A-1, A-2, A-3 and B having the following compositions were prepared.

A-1 Liquid Black coloring leuco dye: Compound 1 9 parts by weight Polyvinyl alcohol 12% aqueous solution 15 parts by weight Water
30 parts by weight A-2 liquid Black coloring leuco dye: Compound ■ 9 parts by weight Polyvinyl alcohol 12% aqueous solution 115 parts 1 [S Water A-3 liquid 30 parts by weight Polyvinyl alcohol 12% aqueous solution 15 parts by weight Water B liquid Bisphenol A 30 parts 1 part 200 parts by weight 66.7 parts by weight Each layer with the above composition was separately sanded to an average particle size of 2 μm.
It was dispersed until it became less than m.

Separately, a solution D having the following composition was prepared.

Liquid D water 80 layers The liquid was dispersed in a homomixer for 10 minutes.

27□35 parts by weight of A-1 solution prepared as above,
Mix 27.35 parts by weight of liquid A-2, 121.6 parts by weight of liquid B, and 100 parts by weight of liquid D, and add 100 parts by weight of a 20% stearamide dispersion and a 30% zinc stearate dispersion to this mixed liquid. , 33.3-fold IHE and 100 parts by weight of a 12% polyvinyl alcohol aqueous solution were added and stirred to prepare a heat-sensitive coating liquid.

This heat-sensitive coating liquid was applied to a high-quality paper of 50 g/m' to a coating weight of 5 g/m' after drying, and then calendered. Obtained a record.

Example 2 A thermosensitive recording material was obtained in the same manner as in Example 1 except that bisphenol A in liquid B was replaced with n-butyl bis(4-hydroxyphenyl)acetate.

Example 3 1. For heat-sensitive paint. 1. 3-) Lis(2-methyl-4-
Hydroxy-5-cyclohexylphenyl)butane 2
A thermosensitive recording material was obtained in exactly the same manner as in Example 2, except that 20 parts by weight of the 0% dispersion liquid was further added.

Example 4 A thermosensitive recording material was obtained in the same manner as in Example 1 except that the amount of liquid A-1 was changed to 49.23 parts and the amount of liquid A-2 was changed to 5.47 parts.

Example 5 A thermosensitive recording material was obtained in the same manner as in Example 1, except that the amount of liquid A-1 was changed to 5.47 parts by weight, and the amount of liquid A-2 was changed to 49.23 parts by weight.

Example 6 The amount of A-2 liquid used was changed to 21.88 parts by weight, and A-
A thermosensitive recording material was obtained in exactly the same manner as in Example 1 except that 5.47 parts by weight of the third liquid was added.

Comparative Example I Thermal recording was carried out in the same manner as in Example 1, except that Compound I in A-1 liquid was replaced with 3-(N-ethyl-N-isoamyl)amino-6-methyl-7-anilinofluorane. I got a body.

Comparative Example 2 The compound in liquid A-1 was 3-N-dibutylamino-6-
A thermosensitive recording material was obtained in exactly the same manner as in Example 1 except that methyl-7-anilinofluorane was used.

Comparative Example 3 A thermosensitive recording material was obtained in the same manner as in Example 1 except that 54.7 parts by weight of Liquid A-1 was used, but that Liquid A-2 was not used.

Comparative Example 4 A thermosensitive recording material was obtained in the same manner as in Example 1 except that 54.7 parts by weight of Liquid A-2 was used, but that Liquid A-1 was not used.

Comparative Example 5 20% of 1.1.3-)lis(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane in thermal paint
A thermosensitive recording material was obtained in exactly the same manner as in Comparative Example 3 except that 20 parts by weight of the dispersion liquid was further added.

Comparative Example 6 A thermosensitive recording material was obtained in exactly the same manner as in Example 2 except that 54.7 parts by weight of liquid A-1 was used but liquid A-2 was not used.

Comparative Example 7 A thermosensitive recording material was obtained in exactly the same manner as in Example 3 except that 1 part by weight of 54.7 parts of Liquid A-1 was used, but that Liquid A-2 was not used.

The performance of the heat-sensitive recording bodies obtained in Evaluation Examples 1 to 6 and Comparative Examples 1 to 7 was evaluated by the following method, and the results are shown in Table 1.

(1) Color development property thermal sensitivity tester: TH-PMD [, Daikane Denki (!!>:
] was used to print under the following printing conditions.

Thermal head: KJT-256-8MF
1-S Applied voltage 24. OV Applied power 0.195 W/dat Pulse time
1.5 m5ec and 1.9 m5ec background and recording density were measured using Macbeth RD-514. The recording part of the thermosensitive recording medium used for the storage test has a pulse time of 1,
The one printed at 9 m5ec was used.

(2) Fingerprint resistance Attach fingerprints to the colored image and white area at 20°C, 65%R
It was stored in H for 30 days. The degree of discoloration and color development of the recording area and white area after storage was examined and evaluated using the following criteria.

Good: ◎, Fair: ○, Poor:

(4) Humidity resistance It was stored for 24 hours under high humidity conditions of 40° C. and 90% RH, and the recorded area and white area after storage were measured using a Macbeth densitometer RD514.

Claims (1)

[Claims] In a heat-sensitive recording material containing, on a support, a colorless to light-colored leuco dye and a color developer that develops color by reacting with the leuco dye, 3-(N-ethyl-N-ethoxypropyl)amino is used as the leuco dye. - A thermosensitive recording material characterized in that 6-methyl-7-anilinofluorane and 3-(N-ethyl-N-furfuryl)amino-6-methyl-7-anilinofluorane are used in combination.