JP3424214B2 - 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 high sensitivity, heat resistance, water resistance and oil resistance.

[0002]

2. Description of the Related Art Generally, a heat-sensitive recording sheet is usually prepared by grinding and dispersing a colorless or light-colored basic colorless dye and an organic developer such as a phenolic substance into fine particles, and then mixing them together to prepare a binder and a filler. A coating solution obtained by adding agents, sensitivity enhancers, lubricants and other auxiliaries to a support such as paper, synthetic paper, film, plastic, etc., such as a hot pen, thermal head, hot stamp, laser light. Color recording is obtained by an instant chemical reaction by heating such as.

These thermal recording sheets are used for measuring recorders, computer terminal printers, facsimiles,
It has been applied to a wide range of fields such as automatic ticket vending machines and bar code labels, but recently, with the diversification and high performance of these recording devices, the quality requirements for thermal recording sheets have become higher. . For example, as recording speed increases, it is required to obtain a clear color image with high density even with a small amount of heat energy, and light resistance on the other hand,
There is a demand for a heat-sensitive recording sheet having excellent storage stability 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.
The heat-sensitive recording material disclosed in Japanese Patent No. 9 is cited, but such a conventional heat-sensitive recording material has a low thermal response, for example, and a sufficient color density cannot be obtained during high-speed recording.

As a method for improving such a defect, 3-N-methyl-N-cyclohexylamino-6-methyl-7-anilinofluorane is used as a leuco dye (JP-A-49-109120), 3- Dibutylamino-
Development of high-sensitivity dyes such as using 6-methyl-7-anilinofluorane (JP-A-59-190891) has been made, and a substance having a good coloring property as a developer 1,7-
Bis (4-hydroxyphenylthio) -3,5-dioxaheptane (JP-A-59-106456), 1,
By using 5-bis (4-hydroxyphenylthio) -3-oxaheptane (JP-A-59-116262) and 4-hydroxy-4'-isopropoxydiphenyl sulfone (JP-B-63-46067). Techniques for achieving high speed and high sensitivity have been disclosed.

Further, in Japanese Patent Laid-Open No. 5-4449,
It is disclosed that an image is stabilized by using a dimerized thiourea compound as a third additive for a color forming component composed of a dye precursor and a salicylic acid developer.

[0007]

However, although these thermal recording sheets have high sensitivity, they generally have a problem in heat resistance such that the image density is lowered when they are stored at a high temperature.

Further, the storage stability of the recorded image is remarkably poor, so that water or sebum components adhere to the color image or contact with a plasticizer (DOP, DOA, etc.) contained in a wrap film such as a vinyl chloride film. Then, there are still drawbacks such as a remarkable decrease in image density and decoloring.

An object of the present invention is to provide a thermosensitive recording sheet having high sensitivity and excellent heat resistance, water resistance and oil resistance by using a specific dimerized thiourea compound as a stabilizer.

[0010]

The dimerized thiourea compound according to the present invention is represented by the following general formula (I).

[Chemical 2] (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom, a lower alkyl group,
Cycloalkyl group, lower alkoxy group, halogen atom,
A nitro group and a cyano group are shown. A is a substituted or unsubstituted C
_{1 to} C ₁₈ alkyl group, aryl group, aralkyl group, acyl group and phenoxycarbonyl group are shown. X represents S or SO ₂ . )

Among these dimerized thiourea compounds,
4,4'-di (phenylthio carbamoylamino) diphenyl sulfide and 4,4'-di (phenylthio Cal <br/> Bamoiruamino) diphenyl sulfone is superior most quality of the heat-sensitive recording sheet.

The present invention solves the above problems all at once by incorporating a specific dimerized thiourea compound represented by the general formula (I) into the thermosensitive color developing layer as a stabilizer.

In the present invention, the compound number and structural formula of the dimerized thiourea compound used as a stabilizer are exemplified, but the invention is not limited thereto.

[0014]

[Chemical 3]

[Chemical 4]

[Chemical 5]

[Chemical 6]

[Chemical 7]

[Chemical 8]

[Chemical 9]

[Chemical 10]

The above dimerized thiourea compounds may be used alone or in combination of two or more as required.

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

<Bisphenol A>4,4'-isopropylidene diphenol (also known as 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 Methylbenzyl 4-hydroxybenzoate

<4-hydroxyphthalic acid diesters> Dimethyl 4-hydroxyphthalate 4-Hydroxyphthalate diisopropyl 4-hydroxyphthalic acid dibenzyl 4-Hydroxyphthalate dihexyl

<Phthalic acid monoesters> Phthalic acid monobenzyl ester Phthalic acid monocyclohexyl ester Phthalic acid monophenyl ester Phthalic acid monomethyl phenyl ester Phthalic acid monoethyl phenyl ester Phthalic acid monopropylbenzyl ester Phthalic acid monohalogen benzyl ester Phthalic acid monoethoxybenzyl ester

<Bis- (hydroxyphenyl) sulfides> 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

<4-Hydroxyphenylarylsulfones>4-hydroxy-4'-isopropoxydiphenylsulfone4-hydroxy-4'-propoxydiphenylsulfone4-hydroxy-4'-n-butyloxydiphenylsulfone 4-hydroxy- 4'-n-propoxydiphenyl sulfone

<4-Hydroxyphenylarylsulfonates> 4-hydroxyphenylbenzenesulfonate 4-hydroxyphenyl-p-tolylsulfonate 4-hydroxyphenylmethylenesulfonate 4-hydroxyphenyl-p-chlorobenzenesulfonate 4- Hydroxyphenyl-p-tert-butylbenzene sulfonate 4-hydroxyphenyl-p-isopropoxybenzene sulfonate 4-hydroxyphenyl-1'-naphthalene sulfonate 4-hydroxyphenyl-2'-naphthalene sulfonate

<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 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

<4-Hydroxybenzoyloxybenzoic acid ester> benzyl 4-hydroxybenzoyloxybenzoate 4-hydroxybenzoyloxy methyl benzoate 4-hydroxybenzoyloxy ethyl benzoate 4-hydroxybenzoyloxypropyl propyl 4-hydroxybenzoyloxy Butyl benzoate 4-hydroxybenzoyloxy isopropyl 4-hydroxybenzoyloxy benzoate tert-butyl 4-hydroxybenzoyloxy hexyl benzoate 4-hydroxybenzoyloxy octyl 4-hydroxybenzoyloxy benzoate Nonyl 4-hydroxybenzoyloxy benzoate Cyclohexyl benzoate 4-hydroxybenzoyloxy β-phenethyl 4-hydroxybenzoyloxy benzoate Phenyl 4-hydroxy-benzoyloxy benzoate α- naphthyl 4-hydroxy-benzoyloxy benzoate β- naphthyl 4-hydroxy-benzoyloxy benzoate sec- butyl

<Bisphenol Sulfones (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'-hydroxyphenyl sulfone 4-hydroxyphenyl-2'-isopropyl-4'-
Hydroxyphenyl sulfone 4-hydroxyphenyl-3'-isopropyl-4'-
Hydroxyphenyl sulfone 4-hydroxyphenyl-3'-sec butyl-4'-
Hydroxyphenyl sulfone 3-chloro-4-hydroxyphenyl-3'-isopropyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-butylphenyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-aminophenyl -4'-hydroxyphenyl sulfone 2-hydroxy-5-t-isopropylphenyl-4 '
-Hydroxyphenyl sulfone 2-hydroxy-5-t-octylphenyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-butylphenyl-3'-chloro-4'-hydroxyphenyl sulfone 2-hydroxy-5-t -Butylphenyl-3'-methyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-butylphenyl-3'-isopropyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-butylphenyl-3 '-Chloro-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-butylphenyl-3'-methyl-4'-hydroxyphenyl sulfone 2-hydroxy-5-t-butylphenyl-3'-isopropyl-4'- Hydroxyphenyl sulfone 2-hydroxy-5-t-butylpheny 2'-methyl-4'-hydroxyphenyl sulfone

<Bisphenolsulfonic acid (II)>4,4'-sulfonyldiphenol2,4'-sulfonyldiphenol3,3'-dichloro-4,4'-sulfonyldiphenol3,3'-dibromo-4 , 4'-Sulfonyldiphenol 3,3 ', 5,5'-Tetrabromo-4,4'-sulfonyldiphenol 3,3'-Diamino-4,4'-sulfonyldiphenol

<Others> p-tert-butylphenol 2,4-dihydroxybenzophenone Novolac type phenolic resin 4-hydroxyacetophenone p-phenylphenol Benzyl-4-hydroxyphenylacetate p-benzylphenol

The basic colorless dye used in the present invention is not particularly limited, but triphenylmethane type, fluorane type, fluorene type, divinyl type and the like are preferable, and specific examples thereof are shown below.

<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-anilinofluorane 3- (N-ethyl-p-toluidino) -6-methyl-
7-anilinofluorane 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane 3-diethylamino-6-methyl-7- (o, p-dimethylanilino) fluoran 3 -Pyrrolidino-6-methyl-7-anilinofluorane 3-piperidino-6-methyl-7-anilinofluorane 3- (N-cyclohexyl-N-methylamino) -6-
Methyl-7-anilinofluorane 3-diethylamino-7- (m-trifluoromethylanilino) fluorane 3-Nn-dibutylamino-6-methyl-7-anilinofluorane 3-Nn-dibutyl Amino-7- (o-chloroanilino) fluorane 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane 3-dibutylamino-6-methyl-7- (o, p -Dimethylanilino) fluorane 3- (N-methyl-N-propylamino) -6-methyl-7-anilinofluorane 3-diethylamino-6-chloro-7-anilinofluorane 3-dibutylamino-7- (O-Chloranilino) fluorane 3-diethylamino-7- (o-chloranilino) fluorane 3-diethylamino-6-methyl-chlorf Olan 3-diethylamino-6-methyl-fluorane 3-cyclohexylamino-6-chlorofluorane 3-diethylamino-benzo [a] -fluorane 3-n-dipentylamino-6-methyl-7-anilinofluorane 2- ( 4-oxo-hexyl) -3-dimethylamino-
6-Methyl-7-anilinofluorane 2- (4-oxo-hexyl) -3-diethylamino-
6-Methyl-7-anilinofluorane 2- (4-oxo-hexyl) -3-dipropylamino-6-methyl-7-anilinofluorane

<Fluorene 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) aminoanilinofluorane 2-chloro-3-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane 2 -Chloro-6-p- (p-dimethylaminophenyl)
Aminoanilinofluorane 2-nitro-6-p- (p-diethylaminophenyl)
Aminoanilinofluorane 2-amino-6-p- (p-diethylaminophenyl)
Aminoanilinofluorane 2-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluorane 2-phenyl-6-methyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane 2- Benzyl-6-p- (p-phenylaminophenyl) aminoanilinofluorane 2-hydroxy-6-p- (p-phenylaminophenyl) aminoanilinofluorane 3-methyl-6-p- (p-dimethyl Aminophenyl)
Aminoanilinofluorane 3-diethylamino-6-p- (p-diethylaminophenyl) aminoanilinofluorane 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-Diacetylethanebis- [2,2,2 ', 2'-tetrakis- (p-dimethylaminophenyl) -ethenyl] -methylmalonic acid dimethyl ester

These dyes can be used alone or in admixture of two or more.

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.

As the binder used in the present invention, completely saponified polyvinyl alcohol having a degree of polymerization of 200 to 1900, partially saponified polyvinyl alcohol, carboxy modified polyvinyl alcohol, amide modified polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol, butyral modified polyvinyl. 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, polyacrylic acid ester, polyvinyl butyral polystyrol and copolymers thereof, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin and coumarone resin. These polymeric substances are water, alcohols, ketones,
In addition to using it by dissolving it in a solvent such as ester or hydrocarbon,
It may be used in a state of being emulsified in water or another medium or dispersed in a paste form and used together depending on the 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 thereof include inorganic or organic fillers such as calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, tanks, titanium oxide, and aluminum hydroxide.

In addition to these, a releasing agent such as a fatty acid metal salt, a lubricant such as waxes, a benzophenone-based or triazole-based UV absorber, a water-proofing agent such as glyoxal, a dispersant, an antifoaming agent, etc. should be used. You can

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 to 8 parts of organic color developer, 0.25 to 2.5 parts of stabilizer, and 1 to 20 parts of filler are used for 1 part of water-soluble colorless dye, and the binder is 10 to 25% in the total solid content.
Is appropriate.

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

Furthermore, an overcoat layer of a polymeric substance containing a filler may be provided on the thermosensitive color developing layer for the purpose of enhancing the storage stability.

An undercoat layer containing an organic filler or an inorganic filler may be provided under the thermosensitive color developing layer for the purpose of enhancing the storage stability and sensitivity.

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

[0048]

The reason why the effect of the present invention is obtained when the specific stabilizer is used in the present invention is considered as follows.

First, what is excellent in the ability of dynamic coloring is
This is because the developer, the dye, and the stabilizer of the present invention have a large melt-dissolution diffusion rate and saturation solubility, and a recorded image can be formed instantaneously 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, thermal recording paper uses a basic colorless dye as an electron donor,
An organic acidic substance such as a phenol compound, an aromatic carboxylic acid or an organic sulfonic acid is used as an electron acceptor.
The heat-melting reaction between the basic colorless dye and the color developer is an acid-base reaction based on electron donation / acceptance, whereby a metastable "charge transfer complex" is formed and a color image is obtained. . At this time, since the stabilizer of the present invention is a specific dimerized thiourea compound having a diphenyl sulfide or diphenyl sulfone skeleton in the molecule, it stabilizes the recorded image by reacting with the leuco dye and the organic developer during the heat melting reaction. It is considered that the stability of the color image is maintained even if the recorded image is exposed to environmental conditions affected by water, oil, and heat for a long period of time.

[0051]

EXAMPLES The present invention will be described below with reference to examples.
In the description, parts indicate parts by weight.

[Example 1 (Test Nos. 1 to 40)] Liquid A (Developer Dispersion Liquid) Developer (see Tables 1 and 3) 6.0 parts 10% polyvinyl alcohol aqueous solution 18.8 parts water 11.2 parts Solution B (dye dispersion) 3- (N-ethyl-N-isoamylamino) -6-methyl-2.0 parts 7-anilinofluorane 10% polyvinyl alcohol aqueous solution 4.6 parts Water 2. 6 parts C liquid (stabilizer dispersion liquid) Dimerized thiourea compound (see Table 1 and Table 3) 4.0 parts 10% aqueous polyvinyl alcohol solution 5.0 parts water 3.0 parts Sand each liquid of the above composition It was ground with a grinder to an average particle size of 1 micron. Next, the dispersion liquids were mixed at the following ratios to prepare coating liquids. Liquid A 36.0 parts Liquid B 9.2 parts Liquid C 12.0 parts Kaolin clay (50% dispersion liquid) 12.0 parts The above coating liquids were applied to one side of a base paper of 50 g / m ² 6.0.
It was coated and dried so as to be g / m ² , and this sheet was treated with a super calender so that the smoothness was 500 to 600 seconds to prepare a heat-sensitive recording sheet.

Comparative Example 1 (Test Nos. 41 to 46) Liquid D (Developer Dispersion Liquid) Developer (see Table 5) 6.0 parts 10% polyvinyl alcohol aqueous solution 18.8 parts water 11.2 Part B liquid (dye dispersion) 3- (N-ethyl-N-isoamylamino) -6-methyl-2.0 parts 7-anilinofluorane 10% polyvinyl alcohol aqueous solution 4.6 parts water 2.6 parts above Each liquid of the composition (1) was ground with a sand grinder to an average particle size of 1 micron. Next, the dispersions were mixed in the following proportions to form a coating liquid, and a thermosensitive recording sheet was prepared in the same manner as in Example 1. Liquid D 36.0 parts Liquid B 9.2 parts Kaolin clay (50% dispersion liquid) 12.0 parts

Comparative Example 2 (Test Nos. 47 to 50) Liquid A (Developer Dispersion Liquid) Developer (see Table 5) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 Part B liquid (dye dispersion) 3- (N-ethyl-N-isoamylamino) -6-methyl-2.0 parts 7-anilinofluorane 10% polyvinyl alcohol aqueous solution 4.6 parts water 2.6 parts E Liquid (stabilizer dispersion liquid) Dimerized thiourea compound (see Table 5) 4.0 parts 10% aqueous polyvinyl alcohol solution 5.0 parts water 3.0 parts Each liquid of the above composition was subjected to an average particle diameter of 1 with a sand grinder. Grinded to micron. Next, the dispersion liquids were mixed at the following ratios to prepare coating liquids. A liquid 36.0 parts B liquid 9.2 parts E liquid 12.0 parts Kaolin clay (50% dispersion liquid) 12.0 parts The above coating liquids were applied to one side of 50 g / m ² base paper. 0
It was coated and dried so as to be g / m ² , and this sheet was treated with a super calender so that the smoothness was 500 to 600 seconds to prepare a heat-sensitive recording sheet.

Tables 2, 4 and 6 show the results of quality performance tests conducted on the thermal recording sheets obtained in the above Examples and Comparative Examples.

[0056]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

Note (1) Dynamic color density; manufactured by Tokyo Shibaura Denki-
Thermal facsimile KB-4800 is used and the applied voltage is 1
The image density recorded at 8.03 V and a pulse width of 3.2 milliseconds was measured with a Macbeth densitometer (RD-914, using an amber filter. The same applies hereinafter).

Note (2) Heat resistance: The thermal paper sample dynamically recorded by the method of Note (1) was subjected to 24 hours under the conditions of 60 ° C. and dry.
After leaving for a while, the recorded area was measured with a Macbeth densitometer. The residual rate is calculated from the following formula.

[Equation 1]

Note (3) Water resistance: The 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 formula.

[Equation 2]

Note (4) Oil resistance: Salad oil was dropped on the thermal paper sample dynamically recorded by the method of Note (1), wiped off with a filter paper that rolls after 10 seconds, and allowed to stand at room temperature for 1 hour. Measured with a Macbeth densitometer. The residual rate is calculated from the following formula.

[Equation 3]

Note (5) The compound numbers and structural formulas of the stabilizers shown in Comparative Example 2 are shown below.

[Chemical 11]

[0062]

【The invention's effect】

(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) The printed part (coloring part) hardly disappears even when it comes into contact with plasticizer, salad oil, vinegar, etc. (oil resistance) (3) The printed part even when it comes into contact with water Hardly disappears. (Water resistance) (4) Images are stable even under high temperature conditions. (Heat-resistant)

Front page continuation (72) Inventor Akio Sekine 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Nihon Paper Manufacturing Co., Ltd. Product Development Laboratory (56) Reference JP-A-6-227142 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) B41M 5/28-5/34 CAPLUS (STN) REGISTRY (STN)

Claims (3)

(57) [Claims] 1. A thermosensitive recording sheet comprising a support and a thermosensitive coloring layer containing a colorless or light-colored basic colorless dye and an organic developer as main components, wherein the thermosensitive coloring layer is a base.
1 to 8 parts of an organic developer with respect to 1 part of a colorless colorless dye, and at least one dimerized thiourea compound represented by the following general formula (I) as a stabilizer is used as a basic colorless dye. Against department
A thermal recording sheet containing 0.25 to 2.5 parts . [Chemical 1] (In the formula, R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R ₆ , R ₇ and R ₈ are each independently a hydrogen atom, a lower alkyl group,
Cycloalkyl group, lower alkoxy group, halogen atom,
A nitro group and a cyano group are shown. A is a substituted or unsubstituted C
_{1 to} C ₁₈ alkyl group, aryl group, aralkyl group, acyl group and phenoxycarbonyl group are shown. X represents S or SO ₂ . ) Wherein said stabilizer is 4,4'-di (phenylthio mosquito <br/> Rubamoiruamino) heat sensitive recording sheet according to claim 1, wherein the diphenyl sulfide. 3. A heat-sensitive recording sheet according to claim 1, wherein the said stabilizer is 4,4'-di (phenylthio mosquito <br/> Rubamoiruamino) diphenyl sulfone.