JP3029008B2 - Thermal recording sheet - Google Patents

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 sheet having excellent heat resistance, water resistance and plasticizer resistance.

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording sheet is prepared by grinding and dispersing a colorless or pale-colored basic colorless dye and an organic color developer such as a phenolic substance into fine particles, and then mixing and dispersing them together. A coating solution obtained by adding an agent, a sensitivity improver, a lubricant and other auxiliaries to a support such as paper, synthetic paper, film, plastic, etc. The color recording is obtained by an instantaneous chemical reaction caused by heating such as described above.

[0003] These thermosensitive recording sheets are used for measuring recorders, computer terminal printers, facsimile,
It has been applied to a wide range of fields such as automatic ticket vending machines and bar code labels, but recently, as these recording devices have been diversified and improved in performance, the required quality of thermal recording sheets has become higher. . For example, it is required that a high-density and vivid color image can be obtained even with a small amount of heat energy accompanying the high-speed recording, and on the other hand, light fastness,
There is a demand for a heat-sensitive recording sheet having excellent storability such as weather resistance and oil resistance.

As a conventional example of a heat-sensitive recording sheet, for example, Japanese Patent Publication No. 43-4160 or Japanese Patent Publication No. 45-1403
However, such a conventional heat-sensitive recording material has, for example, a low thermal response, and cannot provide a sufficient color density at the time of high-speed recording.

As a method for remedying such a defect, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluoran is used as a leuco dye (JP-A-49-109120). Dibutylamino-
Highly sensitive dyes such as those using 6-methyl-7-anilinofluoran (JP-A-59-190891) have been developed, and as a color developing agent, a substance having a good coloring property, 1,7-
Bis (4-hydroxyphenylthio) -3,5-dioxaheptane (JP-A-59-106456);
By using 5-bis (4-hydroxyphenylthio) -3-oxaheptane (JP-A-59-116262) and 4-hydroxy-4'-isopropoxydiphenylsulfone (JP-B-63-46067). Techniques for increasing the speed and increasing the sensitivity have been disclosed.

[0006]

However, although these heat-sensitive recording sheets have high sensitivity, they generally have a problem in heat resistance such that when stored at a high temperature, the background portion develops color (ground fog). . Furthermore, since the storage stability of the recorded image is extremely poor, if water or sebum component adheres to the color-developed image or comes into contact with a plasticizer (DOP, DOA, etc.) contained in a wrap film such as a polyvinyl chloride film, the image density is reduced. However, disadvantages such as a remarkable decrease in color and decolorization still remain.

An object of the present invention is to provide a heat-sensitive recording sheet having high sensitivity and excellent heat resistance, water resistance and plasticizer resistance.

[0008]

According to the present invention, an aminobenzenesulfonamide derivative represented by the following general formula (I) is contained in a thermosensitive coloring layer as an organic developer, and the following formula (II) is used as a stabilizer. 4-benzyloxy-4 '-(2,3-epoxy-2-methylpropoxy) represented by
By incorporating diphenyl sulfone, the above problems have been solved at once.

[0009]

Embedded image (Wherein X is a lower alkyl group having 1 to 4 carbon atoms, 1 carbon atom
~ 3 alkoxy groups, hydrogen atoms, nitro groups, cyano groups,
Represents a halogen atom. m represents an integer of 1 to 3. )

Embedded image

In the present invention, the compound numbers and structural formulas of the aminobenzenesulfonamide derivative used as an organic developer are exemplified, but are not limited thereto. Further, the following aminobenzenesulfonamide derivatives can be used alone or in combination of two or more as needed.

[0011]

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[0012]

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The basic colorless dye used in the present invention is not particularly limited, but triphenylmethane type, fluoran type, fluorene type, divinyl type and the like are preferable, and specific examples thereof are shown below. These dyes can be used alone or in combination of two or more.

<Triphenylmethane leuco dye> 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide [also known as crystal violet lactone] <Fluoran leuco dye (I)> 3-diethylamino -6-methyl-7-anilinofluoran 3- (N-ethyl-p-toluidino) -6-methyl-
7-anilinofluoran 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluoran 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluoran 3 -Pyrrolidino-6-methyl-7-anilinofluoran 3-piperidino-6-methyl-7-anilinofluoran 3- (N-cyclohexyl-N-methylamino) -6
Methyl-7-anilinofluoran 3-diethylamino-7- (m-trifluoromethylanilino) fluoran 3-Nn-dibutylamino-6-methyl-7-anilinofluoran 3-Nn-dibutyl Amino-7- (o-chloroanilino) fluoran 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluoran 3-dibutylamino-6-methyl-7- (o, p -Dimethylanilino) fluoran 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluoran 3-diethylamino-6-chloro-7-anilinofluoran 3-dibutylamino-7- (O-chloroanilino) fluoran 3-diethylamino-7- (o-chloroanilino) fluoran 3-diethylamino-6-methyl-c Lorfluoran 3-diethylamino-6-methyl-fluoran 3-cyclohexylamino-6-chlorofluoran 3-diethylamino-benzo [a] -fluoran 3-n-dipentylamino-6-methyl-7-anilinofluoran 2- ( 4-oxo-hexyl) -3-dimethylamino-
6-methyl-7-anilinofluoran 2- (4-oxo-hexyl) -3-diethylamino-
6-methyl-7-anilinofluoran 2- (4-oxo-hexyl) -3-dipropylamino-6-methyl-7-anilinofluoran 3-diethylamino-6-methyl-7- (m-methylanilino ) Fluorane 3-Dibutylamino-6-methyl-7- (m-methylanilino) fluoran <Fluorene-based leuco dye>3,6,6'-Tris (dimethylamino) spiro [fluorene-9,3'-phthalide] 3, 6,6'-tris (diethylamino) spiro [fluorene-9,3'-phthalide] <Fluoran leuco dye (II)> 2-methyl-6-p- (p-dimethylaminophenyl)
Aminoanilinofluorane 2-methoxy-6-p- (p-dimethylaminophenyl) aminoanilinofluoran 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2 -Chloro-6-p- (p-dimethylaminophenyl)
Aminoanilinofluoran 2-nitro-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-amino-6-p- (p-diethylaminophenyl)
Aminoanilinofluoran 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2- Benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluoran 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluoran 3-methyl-6-p- (p-dimethyl Aminophenyl)
Aminoanilinofluorane 3-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluoran 3-diethylamino-6-p- (p-dibutylaminophenyl) aminoanilinofluorane <Divinyl leuco dye> 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5
6,7-tetrabromophthalide 3,3-bis- [2- (p-dimethylaminophenyl)
-2- (p-methoxyphenyl) ethenyl] -4,5
6,7-tetrachlorophthalide 3,3-bis- [1,1-bis (4-pyrrolidinophenyl) ethylene-2-yl] -4,5,6,7-tetrabromophthalide 3,3- Bis- [1- (4-methoxyphenyl) -1-
(4-pyrrolidinophenyl) ethylene-2-yl]-
4,5,6,7-tetrachlorophthalide <Others> 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2 ,
2-dinitrileethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2-
β-naphthoylethane 1,1-bis- [2 ′, 2 ′, 2 ″, 2 ″ -tetrakis- (p-dimethylaminophenyl) -ethenyl] -2,
2-Diacetylethane bis- [2,2,2 ', 2'-tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

[0015] In addition to the dye, the organic developer may be added with another developer so long as the effect of the present invention is not impaired.

Further, as sensitizers, fatty acid amides such as stearic acid amide and palmitic acid amide, ethylene bisamide, montan wax, polyethylene wax, dibenzyl terephthalate, benzyl p-benzyloxybenzoate, di-p-tolyl carbonate , P-benzylbiphenyl, phenyl α-naphthyl carbonate, 1,4-diethoxynaphthalene, 1-hydroxy-
2-naphthoic acid phenyl ester, 1,2-di- (3-
Methylphenoxy) ethane, di (p-methylbenzyl) oxalate, β-benzyloxynaphthalene, 4-biphenyl p-tolyl ether, O-xylerin-bis- (phenyl ether), 4- (m-methylphenoxymethyl) biphenyl Etc. can also be added.

The binder used in the present invention is a completely saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, a partially saponified polyvinyl alcohol, a carboxy-modified polyvinyl alcohol, an amide-modified polyvinyl alcohol, a sulfonic acid-modified polyvinyl alcohol, a butyral-modified polyvinyl alcohol. Alcohol, other modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, styrene-maleic anhydride copolymer, styrene-butadiene copolymer and ethyl cellulose, cellulose derivatives such as acetyl cellulose, polyvinyl chloride, polyvinyl acetate,
Examples thereof include polyacrylamide, polyacrylate, polyvinyl butyral polystyrene, and copolymers thereof, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, and cumarone resin. These macromolecules are water, alcohol, ketone,
In addition to dissolving in solvents such as esters and hydrocarbons,
It is used in a state of being emulsified or dispersed in a paste form in water or another medium, and may be used in combination depending on required quality.

In the present invention, a known stabilizer metal salt of p-nitrobenzoic acid (Ca, Zn) or metal salt of monobenzyl phthalate (Ca, Zn) is used as long as the effects of the present invention are not impaired. It is also possible to add.

The filler used in the present invention includes silica,
Examples include inorganic or organic fillers such as calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, tanks, titanium oxide, and aluminum hydroxide.

In addition, a releasing agent such as a fatty acid metal salt, a lubricant such as a wax, a benzophenone-based or triazole-based ultraviolet absorber, a water-resistant agent such as glyoxal, a dispersant, and an antifoaming agent. Can be.

The amounts of the organic developer and stabilizer used in the present invention and the types and amounts of other various components are determined according to the required performance and recording suitability, and are not particularly limited. For 1 part of the basic colorless dye, 1 to 8 parts of an organic developer and 1 to 20 parts of a filler are used, and the binder is suitably used in an amount of 10 to 25% of the total solid content.

The desired heat-sensitive recording sheet can be obtained by applying a coating solution having the above composition to any support such as paper, synthetic paper, film, plastic and the like.

Further, an overcoat layer of a polymer substance containing a filler or the like can be provided on the thermosensitive coloring layer for the purpose of enhancing the storage stability. Further, an undercoat layer containing an organic filler or an inorganic filler can be provided below the thermosensitive coloring layer for the purpose of enhancing the storage stability and sensitivity.

The above-mentioned organic color developer, basic colorless dye and optionally added materials are finely divided by a pulverizer such as a ball mill, an attritor, a sand grinder or an appropriate emulsifying device until the particle diameter becomes several microns or less. And a binder and various kinds of additive materials are added according to the purpose to obtain a coating liquid.

[0025]

The reason why the effects of the present invention can be obtained when a specific organic developer and a specific stabilizer are combined in the present invention is considered as follows. First, the dynamic coloring ability is excellent because the dye has a high melt-dissolution diffusion rate and a high saturation solubility with respect to the developer of the present invention, and is instantaneously recorded by instantaneous contact of a high-heat thermal head. An image can be formed.

The reason why the recorded image has extremely high stability in terms of water resistance and plasticizer resistance is explained as follows. In general, a thermosensitive recording paper is constituted by using a basic colorless dye as an electron donor and an organic acidic substance such as a phenol compound, an aromatic carboxylic acid or an organic sulfonic acid as an electron acceptor. The heat-melting reaction between these basic colorless dyes and the developer is an acid-base reaction based on donation and acceptance of electrons, whereby a metastable "charge transfer complex" is formed and a colored image is obtained. .

When a specific aminobenzenesulfonamide derivative as the organic developer of the present invention and a specific diphenylsulfone derivative as a stabilizer are used in combination, the aminobenzenesulfonamide derivative and the basic colorless dye in the color development process are used. And the chemical bonding force between them is extremely increased. on the other hand,
When a stabilizer is not used, and when a developer other than the present invention (for example, benzyl 4-hydroxybenzoate, 4-hydroxy-
4'-isopropoxydiphenyl sulfone, 4,4'-
When isopropylidene diphenol) and the stabilizer of the present invention are used in combination, their chemical bonding strength is weak. Therefore, a thermal recording sheet composed of a combination of a specific aminobenzenesulfonamide derivative, a specific diphenylsulfone derivative and a basic colorless dye is exposed to environmental conditions affected by water, a plasticizer, etc. for a long time. It is considered that the chemical bond is not broken and the stability of the color image is maintained.

In the case of thermal recording, the thermal head is instantaneously heated to a temperature of 200 to 300 ° C. or more. Therefore, the thermal head is the developer of the present invention contained in the recording layer of the thermal recording medium which comes into contact with the thermal head. It is considered that the urea skeleton contained in the aminobenzenesulfonamide derivative undergoes tautomerism, becomes an enol type, exhibits a color developing function, and the lactone ring of the dye precursor is cleaved to develop color.

However, when heat energy is applied slowly, the urea skeleton does not change to an enol-type structure, so that it does not exhibit a developing function, and does not react with the dye precursor, so that the ground color does not occur. Absent. This is considered to be the reason for the high heat resistance.

[0030]

The present invention will be described below with reference to examples and comparative examples. In addition, in description, a part shows a weight part. [Example 1 (Test Nos. 1 to 40)] Solution A (dye dispersion) 3-n-dibutylamino-6-methyl-7-anilinofluoran 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.5 parts Liquid B (developer dispersion liquid) Aminobenzenesulfonamide derivative 6.0 parts (see Tables 1 and 3) 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts Liquid C (stabilizer) Dispersion) 4-benzyloxy-4 '-(2,3-epoxy-2-methylpropoxy) diphenylsulfone 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts water 2.5 parts Each liquid of the above composition Was ground to a particle size of 1 micron with a sand grinder. Next, the dispersion liquid is mixed at the following ratio to obtain a coating liquid. Liquid A (dye dispersion) 9.1 parts Liquid B (developer dispersion) 36.0 parts Liquid C (stabilizer dispersion) 9.1 parts Kaolin clay (50% dispersion) 12.0 parts The coating amount was 5.0 g on one side of 50 g / m ² base paper.
g / m < ² > and dried, and this sheet was treated with a super calender so that the smoothness became 500 to 600 seconds, to obtain a thermosensitive recording paper having black coloring.

Comparative Example 1 (Test Nos. 41 to 45)
A heat-sensitive recording paper was obtained in the same manner as in Example 1 except that the stabilizer for the liquid C was not used.

Comparative Example 2 (Test Nos. 46 to 50) Solution A (dye dispersion) 3-n-dibutylamino-6-methyl-7-anilinofluoran 2.0 parts 10% aqueous solution of polyvinyl alcohol 4 .6 parts water 2.5 parts D liquid (developer dispersion liquid) Developer (see Table 5) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 parts C liquid (stabilizer dispersion liquid) ) 4-Benzyloxy-4 '-(2,3-epoxy-2-methylpropoxy) diphenylsulfone 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.5 parts Each liquid of the above composition was sanded. The particles were ground to a particle size of 1 micron with a grinder. Next, the dispersion liquid is mixed at the following ratio to obtain a coating liquid. Liquid A (dye dispersion) 9.1 parts Liquid D (developer dispersion) 36.0 parts Liquid C (stabilizer dispersion) 9.1 parts Kaolin clay (50% dispersion) 12.0 parts The coating amount was 5.0 g on one side of 50 g / m ² base paper.
g / m ² and dried, and the sheet was treated with a super calender to have a smoothness of 500 to 600 seconds to obtain a thermosensitive recording paper.

The thermal recording papers obtained in the above Examples and Comparative Examples were subjected to the following quality performance tests.
The results are shown in Tables 4 and 6. However, the stabilizer A in Tables 1, 3 and 5 indicates the following compounds. A; 4-benzyloxy-4 '-(2,3-epoxy-
2-methylpropoxy) diphenyl sulfone

Note (1) Dynamic color density; manufactured by Tokyo Shibaura Electric Co., Ltd.
Using thermal facsimile KB-4800, applied voltage 1
The image density recorded at 8.03 V and a pulse width of 3.2 ms was measured with a Macbeth densitometer (RD-914, using an amber filter; the same applies hereinafter). Note (2) Heat resistance: The density of the background after the uncolored thermal paper sample was left for 24 hours under a high-temperature drying condition of 80 ° C. was measured with a Macbeth densitometer. Note (3) Water resistance: A thermal paper sample dynamically recorded by the method of Note (1) was immersed in water at 20 ° C. for 24 hours, dried, and the recorded portion was measured with a Macbeth densitometer. The residual rate is calculated from the following equation.

(Equation 1) Note (4) Plasticity: The image density of the sample dynamically recorded by the method of Note (1) was measured with a Macbeth densitometer, and was regarded as an untreated density. Then, a vinyl chloride film (High Wrap KMA manufactured by Mitsui Toatsu) was superimposed on the front and back surfaces of the recording sample, and the image density was measured with a Macbeth densitometer after standing for 24 hours in a constant temperature tester at 40 ° C. The residual rate is calculated from the following equation.

(Equation 2)

[0035]

[Table 1]

[Table 2]

[0036]

[Table 3]

[Table 4]

[0037]

[Table 5]

[Table 6]

[0038]

【The invention's effect】

(1) Because of its excellent thermal response, a clear high-density image can be obtained even at high speed and high density recording. (High sensitivity) (2) The image area hardly loses color even when it comes into contact with a plasticizer, salad oil, vinegar, or the like. (Chemical resistance) (3) The image area hardly loses color even when it comes into contact with water. (Water resistance) (4) The ground color is stable even under high temperature conditions. (Heat-resistant)

Continuation of the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) B41M 5/30 B41M 5/26

Claims (1)

(57) [Claims] 1. A thermosensitive recording sheet comprising a support having thereon a thermosensitive coloring layer containing a colorless or pale-colored basic colorless dye and an organic developer as main components, wherein said thermosensitive coloring layer comprises an organic developer. A heat-sensitive recording sheet comprising: an aminobenzenesulfonamide derivative represented by the following general formula (I); and a diphenylsulfone derivative represented by the following formula (II) as a stabilizer. Embedded image (Wherein X is a lower alkyl group having 1 to 4 carbon atoms, 1 carbon atom
~ 3 alkoxy groups, hydrogen atoms, nitro groups, cyano groups,
Represents a halogen atom. m represents an integer of 1 to 3. )