JPS63179788A - Thermal recording material - Google Patents

Abstract

PURPOSE:To ensure a highly developed color density and high sensitivity, thereby make the title material suitable for high-speed recording, ensure a high ground brightness and prevent development of ground color or decoloring of a developed color part from occurring due to contact with oils or fats or a plasticizer, by using a specified zinc complex as a color developer and using at least one specified vinyl ether compound. CONSTITUTION:A thermal color forming layer comprising a leuco dye and a color developer is provided on a base. A zinc complex represented by the formula (R)kZn(X)2 is used as the color developer, and at least one vinyl ether compound of the formula shown is used. A thermal recording material with this construction can be produced, for example, by applying a coating liquid for forming the thermal color forming layer which liquid comprises the above- mentioned constituents to an appropriate base such as a paper, a synthetic paper and a plastic film, followed by drying. The amounts of the leuco dye, the color developer and a color sensitivity increasing agent used are suitably 5-40wt.%, 20-60wt.% and 20-60wt.%, respectively.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a heat-sensitive recording material, and particularly to a heat-sensitive recording material that is excellent in color development and other recording properties, and has good image stability.

[Prior art]

General heat-sensitive recording materials include a support such as paper or film, a colorless or light-colored dye such as a leuco dye as a coloring agent, and a phenolic compound (especially bisphenol A) as a coloring agent that causes the dye to develop color when heated. In addition to the color forming system consisting of acidic substances such as organic acids, binders, fillers, sensitivity improvers,
It is provided with a heat-sensitive coloring layer in which a lubricant and other auxiliary agents are dispersed.
No. 4039 and Japanese Unexamined Patent Publication No. 48-27736, it has been widely put into practical use. This type of thermal recording sheet produces a colored image through an instantaneous chemical reaction between a coloring agent and a color developer during heating (a thermal printer or facsimile machine with a built-in thermal head is used for heating). Because of this, compared to other recording materials, recording can be obtained in a short time using relatively simple equipment without complicated processes such as development and fixing, there is less noise generation and environmental pollution, and the cost is lower. Due to its low cost, it is used for copying books, documents, etc., and is also useful as a recording material for various information and measuring instruments such as electronic computers, facsimiles, telex machines, and medical measuring instruments.

However, in the case of this type of leuco-based heat-sensitive recording material,
The disadvantage is that the stability of the recorded image is poor and, for example, the recorded image is easily discolored when it comes into contact with oils or plasticizers such as dioctyl phthalate contained in plastic films.

Conventionally, in order to improve the stability of recorded images, for example, a thermosensitive coloring layer containing a large amount of water-resistant and chemical-resistant resin, a thermosensitive coloring layer containing a resin that hardens by heat or light,
Alternatively, a method has been proposed in which a resin protective layer is formed on the surface to protect the heat-sensitive coloring layer from the effects of chemicals and water, but this method complicates processing, increases costs, and also reduces thermal responsiveness. It has the problem of being stored away.

In order to solve this problem, the inventors made extensive efforts and found that by using a zinc complex represented by the general formula (I) as a color developer for leuco dyes, the present inventors achieved extremely high image stability and heat sensitivity. It has been found that recording material can be obtained.

On the other hand, in recent years, along with the development of society, there has been an increasing demand for higher speed and higher density recording. For this reason, there is a strong desire not only to increase the speed of the recording apparatus itself, but also to develop recording materials that can handle this. Conventionally, in order to make heat-sensitive recording materials suitable for high-speed recording, for example,
No. 39139, JP-A-53-26139, JP-A-53
As described in JP-A-5636, JP-A-53-11036, etc., various waxes, fatty acid amides, alkylated biphenyls, substituted biphenylalkanes, coumarins, diphenylamines, etc., are used in the heat-sensitive coloring layer. There is a method of adding a heat-melting substance as a sensitizer (or melting point depressant). However, these methods cannot be combined with the general formula (
When applied to a heat-sensitive recording material using the zinc complex 1) as a color developer, it is still not sufficient in terms of color density, color sensitivity, background whiteness, water resistance of images, etc.

〔the purpose〕

For the purpose of the present invention, one color development density and one color development sensitivity are sufficient.

It is suitable for high-speed recording, has a high background whiteness, and does not develop color on the background or discoloration of colored areas even when it comes into contact with oils or plasticizers, and can retain images even when it comes in contact with water, such as when immersed in water. An object of the present invention is to provide an extremely practical heat-sensitive recording material that does not have a decrease in density.

〔composition〕

According to the present invention, in a heat-sensitive recording material in which a heat-sensitive coloring layer containing a leuco dye and a color developer is provided on a support, the color developer is composed of general formula (I)(R)k Z n (X )!
(1) (wherein R represents an organic ligand capable of bonding with zinc ion to form a complex via a heteroatom, k represents 2 or 4, and X represents SCN or a halogen atom. ) Using a zinc complex represented by the general formula (II)
Provided is a heat-sensitive recording material characterized in that it uses at least one vinyl ether compound represented by the following.

Specific examples of the zinc complex and ether compound of the present invention are shown below, but the present invention is not limited thereto.

[Zinc complex]

Compound No. Structural Formula The leuco dyes used in the present invention may be applied alone or in a mixture of two or more types, and as such leuco dyes, those applied to this type of heat-sensitive material may be arbitrarily applied, For example, 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 those shown below.

3.3-bis(p-dimethylaminophenyl)-phthalide, 3.3-bis(p-dimethylaminophenyl)-6-dimethylaminophthalide (also known as crystal violet lactone), 3.3-bis(p- dimethylaminophenyl)-6-diethylaminophenyl, 3.3-his(p-dimethylaminophenyl)-6-
Chlorphthalide, 3.3-bis(p-dibutylaminophenyl)phthalide, 3-cyclohexylamino-6-chlorofluoran.

3-dimethylamino-5,7-dimethylfluorane, 3
-diethylamino-7-chlorofluorane, 3-diethylamino-7-methylfluorane, 3-diethylamino-7,8-benzfluorane, 3-diethylamino-6
-Methyl-7-chlorofluorane, 3-(N-p-tolyl-N-ditylamino)-6-methyl-7-anilinofluorane.

3-pyrrolidino-6-methyl-7-anilinofluorane, 2-(N-(3'-trifluoromethylphenyl)
amino)-6-dinithylaminofluorane, 2-(3
, 6-bis(diethylamino)-9-(o-chloroanilino)xantylbenzoic acid lactam), 3-diethylamino-6-methyl-7-(-monotrichloromethylanilino)fluoran.

3-diethylamino-7-(0-chloroanilino)fluoran, 3-dibutylamino-7-(0-chloroanilino)fluoran, 3-N-methyl-N-isoamylamino-6-methyl-
7-anilinofluorane, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-(N,N -diethylamino)-5-methyl-7-(
N.

N-dibenzylamino)fluoran, benzoylleucomethylene blue, 6'-chloro-8'-methoxy-benzoindolino-pyrylosbilane, 6'-bromo-3'-methoxy-benzoindolino-pyrylospirane, 3-(2'- 3-(2'-hydroxy-4'-dimethylaminophenyl)-3-(2'-methoxy- 5'-nitrophenyl) phthalide, 3-(2'-hydroxy-4'-diethylaminophenyl)-3-(2'-methoxy-51-methylphenyl) phthalide.

3-(2'-methoxy-4'-dimethylaminophenyl)-3-(2'-hydroxy-4'-chloro-5'
-methylphenyl)phthalide, 3-morpholino-7-(N-propyl-trifluoromethylanilino)fluorane, 3-pyrrolidino-7-trifluoromethylanilinofluorane, 3-diethylamino-5-chloro-7-(N -benzyl-trifluoromethylanilino)fluorane.

3-Pyrrolidino-7-(di-p-chlorophenyl)methylaminofluorane, 3-diethylamino-5-chloro-7-(α-)dimethylethylamino)fluoran, 3-(N-ethyl-p-toluidino) -7-(α-phenylethylamino)fluoran.

3-diethylamino-7-(o-methoxycarbonylphenylamino)fluoran, 3-diethylamino-5-methyl-7-(α-phenylethylamino)fluoran, 3-diethylamino-7-piperidinofluorane.

2-chloro-3-(N-methyltoluidino)-7-(p
-〇-butylanilino)fluorane, 3-(N-benzyl-N-cyclohexylamino)-5
, 6-penzo 7-α-naphthylamino-4'-bromofluorane, 3-diethylamino-6-chloro-7-anilinofluorane.

3-N-ethyl-N-(2-ethoxypropyl)amino-6-methyl-7-anilinofluorane, 3-N-ethyl-N-tetrahydrofurfurylamino-6-methyl-
7-anilinofluorane, 3-diethylamino-6-methyl-7-mesitidino 4', 5'-benzofluorane, and the like.

In the present invention, in order to bind and support the leuco dye, color developer and auxiliary components on the support, various conventional binders can be used as appropriate, such as polyvinyl alcohol, starch and its derivatives, methoxy Cellulose derivatives such as cellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, and ethylcellulose, sodium polyacrylate, polyvinylpyrrolidone, acrylic amide/acrylic ester copolymer, acrylic amide/acrylic ester/methacrylic acid ternary copolymer , styrene/maleic anhydride copolymer alkali salt, isobutylene/maleic anhydride copolymer alkali salt, polyacrylamide, sodium alginate, gelatin, casein, and other water-soluble polymers, as well as polyvinyl acetate, polyurethane, styrene/butadiene. Copolymer, polyacrylic acid, polyacrylic acid ester, vinyl chloride/
Latex such as vinyl acetate copolymer, polybutyl methacrylate, ethylene/vinyl acetate copolymer, styrene/butadiene/acrylic copolymer, etc. can be used.

In the present invention, in addition to the leuco dye, color developer, and auxiliary components, if necessary, auxiliary additive components commonly used in this type of heat-sensitive recording material, such as fillers, surfactants, thermofusible A sexual substance (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. ,
Examples include organic fine powders such as urea-formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin. Examples of the thermofusible substance include higher fatty acid metal salts such as zinc stearate, calcium stearate, and aluminum stearate, animal and vegetable waxes, mineral waxes, petroleum waxes, higher fatty acids, and their esters and amides.

The heat-sensitive recording material of the present invention is produced, for example, by applying a coating liquid for forming a heat-sensitive layer containing the above-mentioned components onto a suitable support such as paper, synthetic paper, or plastic film, and drying the coated liquid. in this case.

The appropriate amounts of the leuco dye, color developer, and color development sensitivity increasing agent are 5 to 40% by weight, 20 to 60% by weight, and 20 to 60% by weight, respectively.

〔effect〕

The heat-sensitive recording material of the present invention has improved sensitivity, is suitable for high-speed recording, has a high degree of whiteness of the background, and is also resistant to coloring of the background and coloring of the colored area when it comes into contact with oils and plasticizers. It is highly practical as it does not fade and the image density does not decrease even when it comes into contact with water, such as when immersed in water.

These effects can be obtained by using the zinc complex represented by the above formula (1) in combination with a specific ether compound.

〔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.

Furthermore, the antipyrine complex of zinc thiocyanate (compound N01) used in the Examples described later was synthesized as follows.

14-4 g of zinc sulfate (ZnSO, *7H-0) and 29.2 g of potassium thiocyanate were dissolved in 200 mm of water. Separately, a solution of 8.8 g of antipyrine dissolved in 200 mQ of water was prepared.

When it was added dropwise to the above solution while stirring, a white precipitate was immediately generated. This precipitate was filtered, washed with water, dried, and the resulting white powder was recrystallized from a mixed solvent of water and ethanol, with a melting point of 118
24.2 g of white crystals of antipyrine complex of zinc thiocyanate were obtained at ~120°C.

Example 1 The following solutions (A) to (D) were prepared by separately pulverizing and dispersing mixtures having the following compositions for two days using a magnetic ball mill.

[Liquid A]

water
6011 [Liquid B] Water
60/I [Liquid C] 1.4-di(vinyloxyethoxy)benzene 20 parts 5% aqueous solution of methylcellulose 2011 water
60n [D
Liquid] Shinsaku-Fine powder of formalin resin 20 parts Methyl cellulose 5% aqueous solution 20 parts Water
601/
Next, 10 parts of liquid A, 30 parts of liquid B, 30 parts of liquid C, 20 parts of liquid D, and 10 parts of a 20% alkaline aqueous solution of isobutylene-maleic anhydride copolymer were mixed to prepare a thermosensitive coloring layer forming liquid.
This was applied to a high-quality paper of 150 g/rd with a dry adhesion of 4 to 4
An example in which a heat-sensitive coloring layer was provided by coating and drying to give a coating weight of 5 g/rd, and then the layer surface was calendered to have a surface smoothness of 500 to 600 seconds to prepare a heat-sensitive recording material (a). 2 A heat-sensitive recording material (b) was prepared in the same manner as in Example 1, except that the following liquid (E) was used instead of liquid (C) in Example 1.

(E) Solution 1. 20 parts of 3-di(vinyloxyethoxy)benzene 5% aqueous solution of methylcellulose 20 parts of water
6
Example 3 A heat-sensitive recording material (C) was prepared in the same manner as in Example 1 except that the following liquid (F) was used instead of liquid (C) in Example 1.

(F) Liquid 1. 2-di(vinyloxyethoxy)benzene 20 parts Non-aqueous solution of methyl cellulose 20 parts Water
6
0 Comparative Example 1 Example 1 except that water was used instead of liquid [C] in Example 1.
A thermosensitive recording material (d) was prepared in the same manner as above.

Comparative Example 2 A heat-sensitive recording material (e) was produced in the same manner as in Example 1, except that the following liquid (G) was used instead of liquid (C) in Example 1.

(G) Liquid stearamide 20 parts 5% aqueous solution of methylcellulose 20/! water
6011
The heat-sensitive recording materials (a) to (e) obtained as above are
Using a thermal printing experimental device with a thin film head manufactured by Matsushita Electronics Co., Ltd., the pulse width was set to 1.5 cm under the conditions of head power of 0.451/dot, recording time of one line of 20 m5ec/Q, and scanning line density of 8 x 3.85 dots/1IIIl. 6.2.0.
2.4 (msec), and the print density was measured using a Macbeth densitometer RD-514 (Filterly-106). The results are shown in Table-1.

Table 1 Next, thermal recording materials (a) to (e) were printed using a thermal gradient tester (manufactured by Toyo Seiki) at a pressure of 2 kg, a contact time of 1 second, and a temperature of 150°C, with a distance of 4 cm centered around the printed area. Cut it out on all sides, overlap it with a sheet of polyvinyl chloride film (Polywrap V-300 manufactured by Shin-Etsu Polymer ■), and apply a load of 500 g/cm at room temperature.
* After being left on for 24 hours, it was taken out, and the density of the background area and the density of the colored area were measured using a Macbeth densitometer (RD-514) and compared with the density before the test. The results are shown in Table-2.

Table 2 Next, when a thin layer of cottonseed oil was applied to the background and colored areas of the similarly printed samples and the samples were stored at room temperature for 24 hours, samples (,) to (6) all showed coloration in the background area and color development in the colored area. No discoloration was observed.

Next, take a sample printed in the same way and print 4 CIs around the printed part.
100 with 11 square cutouts and 80ra Q of tap water
The sample was immersed in a mQ beaker at room temperature for 24 hours, taken out and dried, and the change in density of one colored area was measured. The results are shown in Table-3.

Table 3 From the above, the heat-sensitive recording material of the present invention has high sensitivity and white background, does not develop color on the background or decolorize the colored area even when in contact with oils or plasticizers, and can be immersed in water. It can be seen that the image density does not decrease even when it comes in contact with water, making it extremely practical.

Claims (1)

[Claims] (1) In a heat-sensitive recording material in which a heat-sensitive coloring layer containing a leuco dye and a color developer is provided on a support, the color developer is of the general formula (I) (R)kZn(X)_2(I) (In the formula, R represents an organic ligand capable of bonding with a zinc ion to form a complex via a hetero atom, k represents 2 or 4, and X represents SCN or a halogen atom.) While using a zinc complex, general formula (II),
▲There are mathematical formulas, chemical formulas, tables, etc.▼(II) A heat-sensitive recording material characterized by using at least one vinyl ether compound represented by the following.