JPH07309071A - Thermal recording material - Google Patents

Abstract

PURPOSE:To obtain a thermal recording material having practically sufficient heat sensibility, with which color disappearance in an image part and coloring in a texture part do not occur at the time of contact with oil and plasticizer, and deterioration in density of the image part is a little when it is dipped into water, by using a compound having a specified structure as a developer and an ester compound having a specified structure as an auxiliary compound. CONSTITUTION:In a thermal recording material, a coloring reaction between a leuco dye and a developer is utilized. For the developer, a compound shown in the formula I is used and an ester compound shown in the formula II and/or the formula III is used as an auxiliary compound. In the formula I, R1 represents a chain hydrocarbon group which is saturated or unsaturated and can be branched, a chain hydrocarbon group which may have a hydroxyl or an ether linkage or a carbonyl group, and an aryl group which may have a substituent. In the formula II, R2 and R3 are the same as the R1 in the formula I. In the formula III, R4 is the same as R1 in the formula I. The thermal recording material has an improved sensibility. The material is suitable for recording at a high speed. The whiteness of the texture of the material is high and coloring in a texture part and color disappearance in a coloring part do not occur.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a heat-sensitive recording material, and more particularly to a heat-sensitive recording material excellent in image stability.

[0002]

2. Description of the Related Art In recent years, the increase in the amount of information, resource saving, labor saving,
Along with social demands such as pollution-free, various recording systems are being put to practical use and improved in the information recording field. Among them, a thermal recording system using a thermal recording material is
(1) The primary color is not required for the development process, (2) the hardware is simple and compact, the maintenance cost is low, (3) the feel is similar to plain paper, and the sheet itself is relatively inexpensive. Due to its characteristics, it has been put to practical use in computer output, medical measurement recorder field, facsimile field, printer field, POS label vending machine ticket, and the like. As the heat-sensitive recording material used in such a system, lactone,
A lactam or spiropyran ring-containing colorless or pale leuco dye and an acidic substance, for example, a thermosensitive coloring layer containing an organic acid or a phenolic compound (Japanese Patent Publication No.
-4160, 45-14039, etc.) are known.
However, the above-mentioned leuco-type heat-sensitive recording material has the drawback that the stability of the recorded image is poor and the color is easily erased. For example, if it comes into contact with oil or a plasticizer (such as dioctyl phthalate) in a plastic film,
There is a problem that the recorded image is erased. In addition, there is also a problem that the concentration of the image portion is drastically reduced when immersed in water.

Several proposals have been made in the past for the purpose of solving this problem. For example, stability of the thermosensitive coloring layer can be improved by incorporating a large amount of resin having good water resistance and chemical resistance into the thermosensitive coloring layer. The thermosensitive coloring layer contains a resin that is cured by heat or light to improve the stability of the thermosensitive coloring layer. For example, the coloring layer is protected from the effects of chemicals and water. On the other hand, in the field of thermal paper, there has been proposed one using a developer having good chemical resistance (JP-A-48-
No. 51716, JP-B-51-25174), in which the use of a specific developer is effective for pressure-sensitive paper but not for thermal recording paper, and it develops color when contacted with a plasticizer. The part is stable, but there is a problem that the background part (uncolored part) is colored. JP 59-1
A specific developer is also disclosed in Japanese Patent No. 1286, but most of these developers are not suitable for heat-sensitive recording materials. That is, the initial density of the background portion is high (background fog), and only a very low-quality thermal recording material can be obtained. Further, many of them cause color development of the background portion by contact with a plasticizer at the same time as the color developing agent in the pressure sensitive paper field. Further, the heat-sensitive recording paper using these color developers has a problem in practical use because the heat sensitivity is not sufficient.

[0004]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and has a practically sufficient heat sensitivity, and also has a decolorization of an image area and a background area in contact with oil or a plasticizer. It is an object of the present invention to provide a heat-sensitive recording material having extremely high image stability, which is not found in the conventional heat-sensitive recording materials in that not only the color is not developed, but also the density of the image area is not significantly lowered even when immersed in water.

[0005]

According to the present invention, a heat-sensitive recording material utilizing a color-developing reaction between a leuco dye and a developer thereof is represented by the following general formula (I). There is provided a heat-sensitive recording material characterized by using a compound represented by the formula and using an ester compound represented by the following formula (II) and / or formula (III) as an auxiliary component.

[Chemical 1]

[Chemical 2]

[Chemical 3]

Specific examples of the compound represented by the general formula (I) include the followings.

[0007]

[Table 1- (1)]

[0008]

[Table 1- (2)]

[0009]

[Table 1- (3)]

[0010]

[Table 1- (4)]

Specific examples of the ester compound represented by the general formula (II) include the following.

[0012]

[Table 2- (1)]

[0013]

[Table 2- (2)]

Examples of the ester compound represented by the general formula (III) include the following.

[0015]

[Table 3- (1)]

[0016]

[Table 3- (2)]

In the heat-sensitive recording material of the present invention, the compound represented by the general formula (I) is used as the color developer and the ester compound represented by the general formula (II) and / or the general formula (III) is used as an auxiliary component. Since it is used together, it has improved sensitivity, is suitable for high-speed recording, has a high background whiteness, and even when it comes into contact with oils and plasticizers, the color of the background and the decolorization of the colored area are erased. However, the image density does not decrease even when it comes into contact with water such as immersion in water, which is extremely practical.

Among the compounds represented by the above-mentioned general formula (I) used as the color developer in the present invention, the background whiteness is high and there is no coloring or coloring part of the background even when contacted with oils and plasticizers. In view of the expressibility of characteristics such as Compound No. I-
3, compound No. It is desirable to use I-29.

The ester compounds represented by the general formulas (II) and (III) used together as an auxiliary component in the present invention are those having a melting point of 40 to 150 ° C. from the viewpoint of storage stability and sensitivity as a heat-sensitive recording material. Particularly preferably 60 to 130
Those at ℃ are preferred. As such an example, the compound No. II-4, No. II-2 ... Compound No. III
-3, No. III-8 and the like. You may use these ester compounds individually or in mixture of 2 or more types.

The leuco dyes used in the present invention may be used alone or in admixture of two or more, and as such leuco dyes, those applied to this type of heat-sensitive recording material are arbitrarily applied, for example, Leuco compounds of dyes such as triphenylmethane type, fluorane type, phenothiazine type, auramine type and spiropyran type 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-diethylaminophthalide,
3,3-bis (p-dimethylaminophenyl) -6-chlorophthalide, 3,3-bis (p-dibutylaminophenyl) phthalide, 3-cyclohexylamino-6-chlorofluorane, 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-
(Np-tolyl-N-ethylamino) -6-methyl-
7-anilinofluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane, 2- {N- (3'-trifluoromethylphenyl) amino} -6-diethylaminofluorane, 2- {3. 6-bis (diethylamino)-
9- (o-chloroanilino) xanthyl benzoate lactam}, 3-diethylamino-6-methyl-7- (m-trichloromethylanilino) fluorane, 3-diethylamino-7- (o-chloroanilino) fluorane, 3-di- n-Butylamino-7- (o-chloroanilino) fluorane, 3-N-methyl-N, n-amylamino-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) fluorane, benzoyl leuco methylene blue, 6'-chloro-
8'-methoxy-benzoindolino-spiropyran, 6 '
-Bromo-3'-methoxy-benzoindolino-spiropyran, 3- (2'-hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-chlorophenyl) phthalide, 3- (2 '-Hydroxy-4'-dimethylaminophenyl) -3- (2'-methoxy-5'-nitrophenyl) phthalide, 3- (2'-hydroxy-4'-diethylaminophenyl) -3- (2'-methoxy -5'-
Methylphenyl) phthalide, 3- (2'-methoxy-4 '
-Dimethylaminophenyl) -3- (2'-hydroxy-4'-chloro-5'-methylphenyl) phthalide, 3-
(N-ethyl-N-tetrahydrofurfuryl) amino-
6-methyl-7-anilinofluorane, 3-N-ethyl-N- (2-ethoxypropyl) amino-6-methyl-
7-anilinofluorane, 3-N-methyl-N-isobutyl-6-methyl-7-anilinofluorane 3-morpholino-7- (N-propyl-trifluoromethylanilino) fluorane, 3-pyrrolidino- 7-m-trifluoromethylanilinofluorane, 3-diethylamino-5
-Chloro-7- (N-benzyl-trifluoromethylanilino) fluorane, 3-pyrrolidino-7- (di-p-
Chlorophenyl) methylaminofluorane, 3-diethylamino-5-chloro-7- (α-phenylethylamino) fluorane, 3- (N-ethyl-p-toluidino)
-7- (α-phenylethylamino) fluorane, 3-
Diethylamino-7- (o-methoxycarbonylphenylamino) fluorane, 3-diethylamino-5-methyl-7- (α-phenylethylamino) fluorane, 3
-Diethylamino-7-piperidinofluorane, 2-chloro-3- (N-methyltoluidino) -7- (pn-
Butylanilino) fluorane, 3- (N-methyl-N-
Isopropylamino) -6-methyl-7-anilinofluorane, 3-di-n-butylamino-6-methyl-7-
Anilinofluorane, 3,6-bis (dimethylamino)
Fluorene spiro (9,3 ′)-6′-dimethylaminophthalide, 3- (N-benzyl-N-cyclohexylamino) -5,6-benzo-7-α-naphthylamino-4 ′
-Bromofluorane, 3-dinormal butylamino-6
-Methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-
7-anilinofluorane 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane 3
-Diethylamino-6-methyl-7-mesitidino-
4 ', 5'-benzofluorane and the like.

In the present invention, in order to bond and support the leuco dye, the color developer and the auxiliary component on the support, various conventional binders can be appropriately used. Examples thereof include polyvinyl alcohol, starch and the like. Derivatives, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose, and other cellulose derivatives, sodium polyacrylate,
Polyvinylpyrrolidone, acrylic acid amide / acrylic acid ester copolymer, acrylic acid amide / acrylic acid ester / methacrylic acid terpolymer, styrene / maleic anhydride copolymer alkali salt, isobutylene / maleic anhydride copolymer alkali Water-soluble polymers such as salts, polyacrylamide, sodium alginate, gelatin, and casein, polyvinyl acetate, polyurethane, styrene / butadiene copolymer, polyacrylic acid, polyacrylic ester, vinyl chloride / vinyl acetate copolymer Latex such as polybutyl methacrylate, ethylene / vinyl acetate copolymer, and styrene / butadiene / acrylic copolymer can be used.

In the present invention, the leuco dye, the color developer, and the auxiliary component may be used together with, if necessary, an auxiliary additive component which is commonly used in heat-sensitive recording materials of this type, such as a filler or a surfactant. A heat-fusible substance (or lubricant) or the like can be used in combination. In this case, as the filler, for example, in addition to silica, zinc oxide, titanium oxide, aluminum hydroxide, zinc hydroxide, barium sulfate, clay, talc, inorganic fine powder such as surface-treated calcium or silica,
Examples include organic fine powders such as urea-formalin resin, styrene / methacrylic acid copolymer, and polystyrene resin. The heat-sensitive recording material of the present invention is produced, for example, by applying a heat-sensitive layer-forming coating liquid containing the above-mentioned components onto a suitable support such as paper, synthetic paper, or plastic film, and drying. In this case, the leuco dye, the color developer, and the auxiliary component are used in an amount of 5 to 40% by weight,
20-60% by weight and 20-60% by weight are suitable.

[0024]

EXAMPLES Next, the present invention will be described in more detail by way of examples. The parts and% shown below are based on weight.

Example 1 Mixtures having the following compositions were separately pulverized and dispersed for 2 days by using a magnetic ball mill [Solution A], [Solution B], [C].
Liquid] and [D liquid] were prepared. [Liquid A] 3-Dinormal butylamino-6-methyl-7-anilinofluorane 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [Liquid B] 4- (β-phenoxyethoxy) phthalic acid 20 parts (Compound of Compound No. I-3) 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts [C liquid] Bis (p-methylbenzyl) oxalate ester 20 parts (Compound of Compound No. II-4) Polyvinyl alcohol 10% aqueous solution 20 parts water 60 parts [solution D] silicon dioxide 20 parts water 80 parts [solution A] 10 parts, solution B 30 parts, solution C 30
Parts, [D liquid] 10 parts and 10 parts of zinc stearate dispersion liquid (concentration 30%) were mixed to prepare a thermosensitive color forming layer forming liquid. This thermosensitive color forming layer forming liquid was applied to commercially available high-quality paper (basis weight: 52 g /
After dye deposition amount after drying on the surface of m ²⁾ is provided with a thermal color-forming layer was coated and dried so that 0.5 g / m ^2, further Bekk smoothness of the surface becomes 500-600 sec Thus, the thermal recording material (a) of the present invention was prepared by calendering.

Example 2 A thermosensitive recording material (b) was prepared in the same manner as in Example 1 except that the following [Solution E] was used instead of [Solution B] in Example 1.
It was created. [Liquid E] 4- (4'-phenoxybutoxy) phthalic acid 20 parts (Compound No. I-29 compound) 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts

Example 3 The following mixture was stirred and dispersed to obtain an intermediate layer forming liquid [F liquid]. [F liquid] Fine hollow particle dispersion (HP-91 manufactured by Rohm and Haas Co., Ltd., copolymer resin mainly composed of styrene and acryl, solid content concentration 38%, average particle diameter 0.7 μm, hollow ratio 80%) 30 parts styrene / Butadiene copolymer latex (concentration of solid content 47.5%) 10 parts Water 60 parts The above intermediate layer forming liquid was used as a commercially available high-quality paper (basis weight 52 g / m 2).
The surface of ² ) was coated and dried to give a weight of 5 g / m ² after drying to obtain an intermediate layer coated paper. Next, the thermosensitive recording medium color-forming layer-forming liquid obtained in Example 1 was applied and dried on the intermediate layer so that the amount of dye adhering after drying was 0.5 g / m ² to form a sensitized color-forming layer. Further, the layer surface was calendered so that the surface smoothness was 500 to 600 seconds to prepare a heat sensitive recording medium recording material (c).

Example 4 A thermosensitive recording material (d) was prepared in the same manner as in Example 3, except that the thermosensitive coloring layer forming liquid used in Example 2 was used.

Example 5 A thermosensitive recording medium recording material (e) was prepared in the same manner as in Example 1 except that the following [G liquid] was used instead of [C liquid]. [Liquid G] 4-Nitrobenzoic acid methyl ester 60 parts (Compound No. III-3 compound) 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts

Example 6 A thermosensitive recording medium recording material (f) was prepared in the same manner as in Example 5 except that the above-mentioned [Solution E] was used instead of the [Solution B] of Example 5.

Example 7 A thermosensitive recording medium recording material (g) was prepared in the same manner as in Example 5 except that the following [Solution H] was used instead of [Solution G] in Example 5. [Liquid H] 4-Chlorobenzoic acid-4'-methylphenyl ester 20 parts (Compound No. III-8 compound) 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts

Example 8 The amount of dye adhering after drying the thermosensitive recording medium color-forming layer forming liquid obtained in Example 5 was 0.
After coating and drying so as to obtain 5 g / m ² , a thermosensitive recording medium coloring layer is provided, and then the layer surface is calendered so that the surface smoothness is 500 to 600 seconds, and the thermosensitive recording material (h). It was created.

Example 9 A thermosensitive recording medium recording material (i) was prepared in the same manner as in Example 8 except that the liquid for forming the coloring layer of the thermosensitive recording medium in Example 6 was used.

Example 10 A thermosensitive recording material (j) was prepared in the same manner as in Example 8 except that the liquid for forming the coloring layer of the thermosensitive recording medium in Example 7 was used.

Comparative Example 1 Example 1 was repeated except that water was used instead of the [C liquid] of Example 1.
Thermal recording material (k) was prepared in the same manner as in (1).

Comparative Example 2 A heat-sensitive recording material (1) was prepared in the same manner as in Example 1 except that the following [solution I] was used instead of the [solution C] in Example 1. [Liquid I] Metata-phenyl 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts

Comparative Example 3 A thermal recording medium recording material (m) was prepared in the same manner as in Example 1 except that the following [Solution J] was used instead of the [Solution C] of Example 1. [Solution J] Stearic acid amide 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts

Comparative Example 4 A thermosensitive recording medium recording material (n) was prepared in the same manner as in Example 1 except that the following [K liquid] was used instead of [C liquid] of Example 1. [K liquid] p-toluenesulfonic acid phenyl ester 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts water 60 parts

Comparative Example 5 A thermal recording medium recording material (o) was prepared in the same manner as in Example 1 except that the following [Liquid solution] was used instead of [Liquid solution B] in Example 1. [Liquid L] Bisphenol A 20 parts 10% aqueous solution of polyvinyl alcohol 20 parts Water 60 parts

Comparative Example 6 A thermosensitive recording material (p) was prepared in the same manner as in Example 3, except that the thermosensitive color developing layer forming liquid used in Comparative Example 1 was used.

Comparative Example 7 A thermosensitive recording material (q) was prepared in the same manner as in Example 3, except that the thermosensitive coloring layer forming liquid used in Comparative Example 2 was used.

Comparative Example 8 A thermosensitive recording material (r) was prepared in the same manner as in Example 3 except that the thermosensitive coloring layer forming liquid used in Comparative Example 3 was used.

Comparative Example 9 A thermosensitive recording material (s) was prepared in the same manner as in Example 3 except that the thermosensitive color developing layer forming liquid used in Comparative Example 4 was used.

Comparative Example 10 A thermosensitive recording material (t) was prepared in the same manner as in Example 3 except that the thermosensitive color developing layer forming liquid used in Comparative Example 5 was used. The thermal recording materials (a) to (t) obtained as described above were used in a thermal printing experimental apparatus having a thin film head manufactured by Matsushita Electronic Components Co., Ltd. to obtain a head power of 0.45.
V / dot, 1 line recording time 20 msec / l, scanning cotton density 8 × 3.85 dots / mm, pulse width 1.6, 2.0, 2.4 (mmec), and print density Macbeth densitometer RD-514 (filter V-
106). The results are shown in Table 4.

[0045]

[Table 4]

Next, the thermosensitive recording materials (a) to (t) were heated with a thermal tilt tester (manufactured by Toyo Seiki) at a pressure of 2 kg and a contact time of 1
Second, print under the condition of 150 ° C., cut out in a 4 cm square centering on the printed part, and stack 3 polyvinyl chloride films (Polywrap V-300 manufactured by Shin-Etsu Polymer Co., Ltd.) on this, 40
After applying a load of 500 g / cm ² for 16 hours under the condition of drying at ℃, it was taken out and the density of the background part and the density of the color development part were measured with a Macbeth densitometer (RD-514) and compared with the density before the test. The results are shown in Table 5.

[0047]

[Table 5]

Next, a sample printed in the same manner was cut out in a 4 cm square centering on the printed part, and 80 ml of tap water was put in 1
The sample was immersed in a 00 ml beaker at room temperature for 24 hours, taken out and dried, and then the change in the density of the color-developed portion was measured. The results are shown in Table 6.

[0049]

[Table 6]

[0050]

The heat-sensitive recording material of the present invention has improved sensitivity, is suitable for high-speed recording, has a high degree of background whiteness, and can be removed by contact with oils and plasticizers. There is no coloring or decolorization of the coloring part, soaking in water, etc.
It is extremely practical because the image density does not decrease even when it comes into contact with water.

Claims (1)

[Claims] 1. A heat-sensitive recording material utilizing a color-forming reaction between a leuco dye and a color developing agent thereof, wherein a compound represented by the following general formula (I) is used as the color developing agent and as an auxiliary component. A heat-sensitive recording material comprising an ester compound represented by the following general formula (II) and / or general formula (III). [Chemical 1] [Chemical 2] [Chemical 3]