JP2671282B2 - 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 oil 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 image density is reduced.

Further, since the storage stability of the recorded image is remarkably poor, water or sebum components adhere to the color image, or come into contact with a plasticizer (DOP, DOA, etc.) contained in a wrap film such as a PVC film. As a result, disadvantages such as a remarkable decrease in image density and decoloration 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 oil resistance.

[0009]

According to the present invention, a specific epoxidized diphenyl sulfone derivative represented by the general formula (I) is contained as a stabilizer in a thermosensitive coloring layer, and a basic colorless dye represented by the following formula (II) ), 3-n-dibutylamino-6-methyl-7- (m-methylanilino)
By containing fluoran, the above problems are solved all at once.

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Specific examples of the epoxidized diphenylsulfone derivative represented by the above general formula (I) used in the present invention include, for example, those represented by the following compound No.

[0011]

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Of course, the present invention is not limited to these,
If necessary, two or more compounds can be used in combination.

In the present invention, bisphenol A, 4-hydroxybenzoic acid ester, 4-hydroxyphthalic acid diester, phthalic acid monoester, bis- (hydroxyphenyl) sulfide,
Hydroxyphenylarylsulfones, 4-hydroxyphenylarylsulfonates, 1,3-di [2-
(Hydroxyphenyl) -2-propyl] -benzenes, 4-hydroxybenzoyloxybenzoic acid esters, and bisphenolsulfones. Specific examples of these are shown below.

Bisphenol A 4,4'-isopropylidene diphenol (also called bisphenol A) 4,4'-cyclohexylidene diphenol p, p '-(1-methyl-normalhexylidene) diphenol 1,7 -Di (4-hydroxyphenylthio) -3,5-
Dioxaheptane

4-Hydroxybenzoic acid esters Benzyl 4-hydroxybenzoate Ethyl 4-hydroxybenzoate Propyl 4-hydroxybenzoate Isopropyl 4-hydroxybenzoate Butyl 4-hydroxybenzoate Isobutyl 4-hydroxybenzoate 4-Hydroxybenzoate Methyl benzyl

4-hydroxyphthalic acid diesters dimethyl 4-hydroxyphthalate diisopropyl 4-hydroxyphthalate dibenzyl 4-hydroxyphthalate dihexyl 4-hydroxyphthalate

Monoesters of phthalic acid Monobenzyl phthalate Monocyclohexyl phthalate Monophenyl phthalate Monomethyl phenyl phthalate Monoethyl phenyl phthalate Monopropyl benzyl phthalate Monohalogen benzyl phthalate Monoethoxy phthalate Benzyl ester

Bis- (hydroxyphenyl) sulfide
S bis - (4-hydroxy -3-tert-butyl-6
Methylphenyl) sulfide bis- (4-hydroxy-2,5-dimethylphenyl)
Sulfide bis- (4-hydroxy-2-methyl-5-ethylphenyl) sulfide bis- (4-hydroxy-2-methyl-5-isopropylphenyl) sulfide bis- (4-hydroxy-2,3-dimethylphenyl)
Sulfide bis- (4-hydroxy-2,5-dimethylphenyl)
Sulfide bis- (4-hydroxy-2,5-diisopropylphenyl) sulfide bis- (4-hydroxy-2,3,6-trimethylphenyl) sulfide bis- (2,4,5-trihydroxyphenyl) sulfide bis- ( 4-hydroxy-2-cyclohexyl-5-methylphenyl) sulfide bis- (2,3,4-trihydroxyphenyl) sulfide bis- (4,5-dihydroxy-2-tert-butylphenyl) sulfide bis- (4- Hydroxy-2,5-diphenylphenyl) sulfide bis- (4-hydroxy-2-tert-octyl-5)
-Methylphenyl) sulfide

[0019] 4-hydroxyphenylaryl sulfone
S 4-hydroxy-4'-isopropoxydiphenylsulfone 4-hydroxy-4'-propoxy diphenyl sulfone 4-hydroxy-4'-n-butyl sulfone 4-hydroxy-4'-n-propoxy diphenyl sulfone

[0020] 4-hydroxyphenylarylsulfona
Over preparative such 4-hydroxyphenyl benzenesulfonate 4-hydroxyphenyl -p- tolyl sulfonate 4-hydroxyphenyl-methylene sulfonate 4-hydroxyphenyl -p- chlorobenzene sulfonate 4-hydroxyphenyl -p-tert-butyl-benzenesulfonyl Nato 4-hydroxyphenyl-p-isopropoxybenzenesulfonate 4-hydroxyphenyl-1'-naphthalenesulfonate 4-hydroxyphenyl-2'-naphthalenesulfonate

1,3-di [2- (hydroxyphenyl)
-2-propyl] benzenes 1,3-di [2- (4-hydroxyphenyl) -2-propyl] benzene 1,3-di [2- (4-hydroxy-3-alkylphenyl) -2-propyl] benzene Benzene 1,3-di [2- (2,4-dihydroxyphenyl)-
2-propyl] benzene 1,3-di [2- (2-hydroxy-5-methylphenyl) -2-propyl] benzene

Resorcinols 1,3-dihydroxy-6 (α, α-dimethylbenzyl) -benzene

[0023] 4-hydroxybenzoyloxybenzoic acid
Ester benzyl 4-hydroxybenzoyloxybenzoate methyl 4-hydroxybenzoyloxybenzoate ethyl 4-hydroxybenzoyloxybenzoate propyl 4-hydroxybenzoyloxybenzoate butyl 4-hydroxybenzoyloxybenzoate isopropyl 4-hydroxybenzoyloxybenzoate 4 Tert-butyl 4-hydroxybenzoyloxybenzoate hexyl 4-hydroxybenzoyloxybenzoate octyl 4-hydroxybenzoyloxybenzoate nonyl 4-hydroxybenzoyloxybenzoate cyclohexyl 4-hydroxybenzoyloxybenzoate 4-hydroxybenzoyloxybenzoate β- Phenethyl 4-hydroxybenzoyloxybenzoate phenyl 4-hydroxybenzoyloxybenzoate α- naphthyl 4-hydroxy-benzoyloxy benzoate β- naphthyl 4-hydroxy-benzoyloxy benzoate sec- butyl

Bisphenolsulfones (I) bis- (3-1-butyl-4-hydroxy-6-methylphenyl) sulfone bis- (3-ethyl-4-hydroxyphenyl) sulfone bis- (3-propyl-4-) (Hydroxyphenyl) sulfone bis- (3-methyl-4-hydroxyphenyl) sulfone bis- (2-isopropyl-4-hydroxyphenyl)
Sulfone bis- (2-ethyl-4-hydroxyphenyl) sulfone bis- (3-chloro-4-hydroxyphenyl) sulfone bis (2,3-dimethyl-4-hydroxyphenyl) sulfone bis (2,5-dimethyl-4) -Hydroxyphenyl) sulfone bis- (3-methoxy-4-hydroxyphenyl) sulfone 4-hydroxyphenyl-2'-ethyl-4'-hydroxyphenylsulfone 4-hydroxyphenyl-2'-isopropyl-4'-
Hydroxyphenylsulfone 4-hydroxyphenyl-3'-isopropyl-4'-
Hydroxyphenylsulfone 4-hydroxyphenyl-3'-secbutyl-4'-
Hydroxyphenylsulfone 3-chloro-4-hydroxyphenyl-3'-isopropyl-4'-hydroxyphenylsulfone 2-hydroxy-5-t-butylphenyl-4'-hydroxyphenylsulfone 2-hydroxy-5-t-aminophenyl -4'-hydroxyphenylsulfone 2-hydroxy-5-t-isopropylphenyl-4 '
-Hydroxyphenylsulfone 2-hydroxy-5-t-octylphenyl-4'-hydroxyphenylsulfone 2-hydroxy-5-t-butylphenyl-3'-chloro-4'-hydroxyphenylsulfone 2-hydroxy-5-t -Butylphenyl-3'-methyl-4'-hydroxyphenylsulfone 2-hydroxy-5-tert-butylphenyl-3'-isopropyl-4'-hydroxyphenylsulfone 2-hydroxy-5-tert-butylphenyl-2 '-Methyl-4'-hydroxyphenylsulfone

Bisphenolsulfonic acid (II) 4,4'-sulfonyldiphenol 2,4'-sulfonyldiphenol 3,3'-dichloro-4,4'-sulfonyldiphenol 3,3'-dibromo-4,4 '-Sulfonyldiphenol 3,3', 5,5'-tetrabromo-4,4'-sulfonyldiphenol 3,3'-diamino-4,4'-sulfonyldiphenol

Other p-tert-butylphenol 2,4-dihydroxybenzophenone novolak type phenol resin 4-hydroxyacetophenone p-phenylphenol benzyl-4-hydroxyphenylacetate p-benzylphenol

In the present invention, other fluoran leuco dyes can be used in combination as long as the effects of the present invention are not impaired, and specific examples are shown below.

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-dibutylamino-6-methyl-7-anilinofluoran 3-diethylamino-6-chloro-7-ani Linofluoran 3-dibutylamino-7- (o-chloroanilino) fluoran 3-diethylamino-7- (o-chloroanilino) fluoran

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 and the like can also be added.

As the binder used in the present invention, a fully silicified polyvinyl alcohol having a degree of polymerization of 200 to 1900, a partially silicified polyvinyl alcohol, a carboxy modified polyvinyl alcohol, an amide modified polyvinyl alcohol, a sulfonic acid modified polyvinyl alcohol, and a butyral modified polyvinyl are used. 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 p-nitrobenzoic acid metal salt (Ca, Zn) or phthalic acid monobenzyl ester metal salt (Ca, Zn) is used within a range that does not impair the effects of the present invention. It is also possible to add.

The filler used in the present invention is 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-proofing agent such as glyoxal, a dispersant, and an antifoaming agent. Can be.

The amounts of the stabilizer and basic colorless dye used in the present invention, and the types and amounts of various other components are determined according to the required performance and recording suitability, and are not particularly limited, but usually a base is used. 1-8 parts of organic colorless dye, 1-8 parts of organic developer, 0.25-2.5 parts of stabilizer, 1-20 parts of filler are used, and the binder is 10-25% in the total solid content.
Is appropriate.

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

Further, an overcoat layer of a filler-containing polymer material 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 developer, basic colorless dye and, if necessary, materials to be added are finely divided by a pulverizer such as a ball mill, an attritor, a sand grinder or an appropriate emulsifying apparatus 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.

[0039]

The reason why the effects of the present invention can be obtained when a specific stabilizer and a specific dye are combined in the present invention is considered as follows.

First, what is excellent in dynamic coloring ability is that
This is because the dye has a high melt-dissolution diffusion rate and a high saturation solubility with respect to the stabilizer of the present invention, and a recorded image can be instantaneously formed by instantaneous contact of a high-heat thermal head.

The reason why the recorded image is extremely stable in terms of heat resistance, water resistance and oil resistance is explained as follows. Generally, thermosensitive recording paper uses a basic colorless dye as an electron donor,
Organic acidic substances such as phenol compounds, aromatic carboxylic acids, and organic sulfonic acids are configured as electron acceptors.
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. . At this time, it is presumed that the inclusion of the epoxidized diphenylsulfone derivative in this system causes the epoxy group to open during the heat melting reaction, reacting with the leuco dye and the organic developer, and stabilizing the recorded image. Is done. In this reaction process, a specific epoxidized diphenyl sulfone derivative and a specific fluorane-based leuco dye 3-dibutylamino-6-
When methyl-7- (m-methylanilino) fluorane is combined, the ring-opening reaction of this epoxy group occurs actively, which causes the recorded image to be exposed to environmental conditions affected by water, oil and heat for a long period of time. It is considered that the stability of the color image is maintained.

[0042]

The present invention will be described below with reference to examples.
In addition, in description, a part shows a weight part. [Example 1 (Test Nos. 1 to 8)] Solution A (developing agent dispersion) Developer (see Table 1) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 parts B solution (Dye dispersion) Leuco dye (see Table 1) 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.6 parts C solution (stabilizer dispersion) Diphenyl sulfone derivative (see Table 1) 4.0 parts 10% polyvinyl alcohol aqueous solution 5.0 parts water 3.0 parts Each liquid of the above composition was ground with a sand grinder to an average particle diameter of 1 micron. Subsequently, the dispersion liquid was mixed at the following ratio to obtain a coating liquid. Liquid A 36.0 parts Liquid B 9.2 parts Liquid C 12.0 parts Kaolin clay (50% dispersion) 12.0 parts Each of the above coating liquids is applied to one surface of a 50 g / m ² base paper 6.0.
g / m ² and dried, and this sheet was treated with a super calender so that the smoothness became 500 to 600 seconds to prepare a heat-sensitive recording sheet.

[Comparative Example 1 (Test Nos. 9 to 11)] Liquid D (developer dispersion liquid) 4-hydroxy-4'-isopropoxydiphenyl sulfone 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 parts E liquid (dye dispersion) leuco dye (see Table 1) 2.0 parts 10% polyvinyl alcohol aqueous solution 4.6 parts water 2.6 parts F liquid (stabilizer dispersion) diphenyl sulfone derivative (Table 1) Reference) 4.0 parts 10% aqueous polyvinyl alcohol solution 5.0 parts water 3.0 parts Each solution of the above composition was ground to an average particle size of 1 micron with a sand grinder. Next, a dispersion was mixed at the following ratio to form a coating liquid, and a heat-sensitive recording sheet was prepared in the same manner as in Example 1. D liquid 36.0 parts E liquid 9.2 parts F liquid 12.0 parts Kaolin clay (50% dispersion liquid) 12.0 parts

Comparative Example 2 (Test Nos. 12 to 14) Liquid D (developer dispersion liquid) 4-hydroxy-4'-isopropoxydiphenyl sulfone 5.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 parts E solution (dye dispersion) leuco dye (see Table 1) 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts water 2.6 parts Average particle size of each solution of the above composition with a sand grinder Grinded to 1 micron. Next, a dispersion was mixed at the following ratio to form a coating liquid, and a heat-sensitive recording sheet was prepared in the same manner as in Example 1. Liquid D 36.0 parts Liquid E 9.2 parts Kaolin clay (50% dispersion liquid) 12.0 parts

The results of quality tests performed on the heat-sensitive recording sheets obtained in the above Examples and Comparative Examples are summarized in Table 1.

[0046]

[Table 1]

[Table 2]

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: A heat-sensitive paper sample dynamically recorded by the method of Note (1) was left under a condition of 60 ° C. and dry for 24 hours, and the recorded portion was measured with a Macbeth densitometer. The residual rate is calculated from the following equation.

(Equation 1) Note (3) Water resistance: A thermal paper sample dynamically recorded by the method of Note (1) was immersed in cold 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 2) Note (4) Oil resistance; salad oil was dropped on a thermal paper sample dynamically recorded by the method described in Note (1), wiped off with a filter paper after 10 seconds and left at room temperature for 1 hour. Measured with a meter. The residual rate is calculated from the following equation.

(Equation 3)

In Table 1 above, for the leuco dye, the symbol A
Is 3-n-dibutylamino-6-methyl-7- (m-methylanilino) fluorane, symbol B is 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane, symbol C Is 3-dibutylamino-6-methyl-7-anilinofluorane, and the symbol D is 3- (n-cyclohexyl-N-methylamino) -6-methyl-7-anilinofluorane.

[0049]

(1) Since the thermal response is excellent, a clear high density image can be obtained even at high speed and high density recording. (High sensitivity) (2) Printed part (colored part) hardly loses color even when it comes into contact with plasticizer, salad oil, vinegar, etc. (Oil resistance) (3) Printed part even when it comes in contact with water Hardly loses color. (Water resistance) (4) The image is stable even under high temperature conditions. (Heat-resistant)

 ─────────────────────────────────────────────────── --Continued from the front page (56) References JP-A-2-215589 (JP, A) JP-A-2-227286 (JP, A) JP-A-60-123556 (JP, A) JP-A-60- 149665 (JP, A) JP-A-3-178972 (JP, A) JP-A-5-238899 (JP, A)

Claims (1)

(57) [Claims] 1. A thermosensitive recording sheet comprising a support and a thermosensitive coloring layer containing a colorless or pale-colored basic colorless dye and an organic developer as main components, wherein the thermosensitive coloring layer serves as a stabilizer. A heat-sensitive recording sheet comprising a compound represented by the general formula (I) and a fluoran leuco dye represented by the following formula (II) as a basic colorless dye. Embedded image