JPH08142524A - Thermal recording sheet - Google Patents

Abstract

PURPOSE: To obtain a thermal recording sheet having high sensitivity and excellent in heat resistance and oil resistance by using a specific sulfone type phenol coupler as an org. coupler and using a specific aminobenzenesulfonamide derivative as a stabilizer. CONSTITUTION: A sulfone type phenol coupler represented by formula I (wherein R1 is a hydroxy group, an n-propoxy group, an isoproxy group or an n-butoxy group) or formula II is added to a thermal color forming layer as an org. coupler and a specific aminobenzenesulfonamide derivative represented by formula III (wherein X is an oxygen atom or a sulfur atom and R1 is a non-substituted or substituted aralkyl group, a naphthyl group, a lower alkyl group, a lower alkenyl group or a cycloalkyl group) is added thereto as stabilizer in a ratio of 0.08-0.8 pts. per 1 pts of the org. coupler. Therefore, at the time of thermal melting reaction, the specific org. coupler and a leuco dye are reacted to generate the stabilization of a recording image and the stability of a developed color image is kept.

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 as a leuco dye (Japanese Patent Laid-Open No. 49-
109120), 3-dibutylamino-6-methyl-7-anilinofluorane (JP-A-59-19089).
No. 1) has been developed, and 1,7-bis (4-hydroxyphenylthio) -3,5-dioxaheptane (Japanese Patent Laid-Open No. 59-106) has been developed as a developer.
456), 1,5-bis (4-hydroxyphenylthio) -3-oxaheptane (JP-A-59-1162).
62), 4-hydroxy-4'-isopropoxydiphenyl sulfone (Japanese Patent Publication No. 63-46067).
There is disclosed a technique for increasing the speed and sensitivity of the thermal recording sheet by using a substance having a good color forming property such as.

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, these heat-sensitive recording sheets have high sensitivity, but generally have a problem with heat resistance such that when they are stored at a high temperature, the image density is lowered. ● Furthermore, the storage stability of the recorded image is extremely poor, so if water or sebum components adhere to the colored image or if it comes in contact with a plasticizer (DOP, DOA, etc.) contained in a wrap film such as a vinyl chloride film, the image Disadvantages such as a marked decrease in density and decolorization still remain.

The object of the present invention is to use a specific sulfone-based phenol developer as an organic developer and a specific aminobenzenesulfonamide derivative as a stabilizer to obtain high sensitivity, heat resistance and water resistance. Another object of the present invention is to provide a heat-sensitive recording sheet having excellent oil resistance.

[0009]

The present invention comprises a specific sulfone-based phenol developer represented by the following general formula (I) or (II) as an organic developer in a thermosensitive color developing layer, and As a stabilizer, the specific aminobenzenesulfonamide derivative represented by the general formula (III) is added to 1 part of the organic developer in an amount of 0.
The above-mentioned problems are solved all at once by containing it in a ratio of 08 to 0.8 part.

[0010]

[Chemical 4] (In the formula, R ₁ represents a hydroxy group, an n-propoxy group, an isopropoxy group, or an n-butoxy group.)

Embedded image

[Chemical 6] (In the formula, X represents an oxygen atom or a sulfur atom, R ₁ is an unsubstituted or substituted aralkyl group, a naphthyl group,
It represents a lower alkyl group having 1 to 6 carbon atoms, a lower alkenyl group having 1 to 6 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms. )

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

[0012]

[Chemical 7]

Embedded image

[Chemical 9]

[Chemical 10]

[Chemical 11]

The above-mentioned aminobenzenesulfonamide derivatives can be used alone or in combination of two or more as required.

The following compounds may be mentioned as organic developers used in the present invention. 4-Hydroxy-4'-isopropoxydiphenyl sulfone 4-Hydroxy-4'-n-propoxydiphenyl sulfone 4-Hydroxy-4'-n-butoxydiphenyl sulfone 2,4'-Dihydroxydiphenyl sulfone bis- (3-allyl- 4-hydroxyphenyl) sulfone

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-anilinofluoran 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-ku Lorfluorane 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)
Aminoanilinofluoran 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-Diacetylethane bis- [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.

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.

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 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 release 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 a basic colorless colorant is added to 1 part of the organic developer. Dye 0.3-0.6 parts, stabilizer 0.0
8 to 0.8 parts and 1 to 3 parts of filler are used, and the binder is preferably 10 to 25% by weight based on the total solid content.

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, nonwoven fabric and the like.

Further, an overcoat layer of a polymeric substance containing a filler or the like may be provided on the thermosensitive color developing layer for the purpose of improving storage stability.

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

The above-mentioned organic color developer, basic colorless dye and materials to be added as necessary are pulverized by a pulverizer such as a ball mill, an attritor, a sand grinder or an appropriate emulsifying device until the particle diameter becomes 1 micron or less. Then, the binder and various additives according to the purpose are added to obtain a coating liquid.

[0033]

The stabilizer of the present invention has its own color developing ability, but is far inferior to the color developing ability of the organic color developing agent specified in the present invention. However, due to the relationship with the specified organic developer, when it is used in a ratio of 0.08 to 0.8 part with respect to 1 part of the developer, it exhibits a function as a stabilizer as described below. .

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

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. . Since the stabilizer of the present invention is a specific aminobenzenesulfonamide derivative having a urea (thiourea) skeleton and a sulfonamide skeleton in the molecule, the organic developer and leuco compound specified in the present invention during the heat melting reaction. Stabilization of the recorded image occurs by reacting with the dye, and therefore it is considered that the stability of the colored 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. .

If the amount of the stabilizer used is less than 0.08 part per 1 part of the organic color developer, the desired effect cannot be obtained, and if it is more than 0.8 part, dilution with the stabilizer occurs and the sensitivity is lowered. Cause decrease.

[0037]

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% aqueous polyvinyl alcohol 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) Stabilizer (see Table 1 and Table 3) 4.0 parts 10% polyvinyl alcohol aqueous solution 5.0 parts water 3.0 parts Each liquid of the above composition is averaged with a sand grinder. It was ground to a 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 in} an amount of 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) Stabilizer (see Table 5) 4.0 parts 10% polyvinyl alcohol aqueous solution 5.0 parts water 3.0 parts Each liquid of the above composition is ground with a sand grinder to an average particle size of 1 micron. Crushed. 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.

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

[0042]

[Table 1]

[Table 2]

[Table 3]

[Table 4]

[Table 5]

[Table 6]

Note (1) Dynamic color density; manufactured by Tokyo Shibaura Electric Co., Ltd.
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 heat-sensitive 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 12]

[0048]

The heat-sensitive recording sheet according to the present invention has the following excellent features. (1) High sensitivity: Due to excellent thermal response, high speed,
A clear high-density image can be obtained even in high-density recording. (2) Oil resistance: The printed part (colored part) is hardly decolored even when contacted with a plasticizer, salad oil, vinegar and the like. (3) Water resistance: The printed portion is hardly erased even when contacted with water. (4) Heat resistance: The image is stable even under high temperature conditions.

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Akio Sekine 1-30-6 Kamiochiai, Shinjuku-ku, Tokyo Inside Nippon Paper Industries Co., Ltd. Product Development Laboratory

Claims (1)

[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 an organic developer. As a stabilizer, an aminobenzenesulfonamide derivative represented by the following general formula (III) is contained as a stabilizer in an amount of 0 parts per 1 part of the organic developer. A heat-sensitive recording sheet containing 0.08 to 0.8 parts by weight. Embedded image (In the formula, R ₁ represents a hydroxy group, an n-propoxy group, an isopropoxy group or an n-butoxy group.) Embedded image (In the formula, X represents an oxygen atom or a sulfur atom, R ₁ is an unsubstituted or substituted aralkyl group, a naphthyl group,
It represents a lower alkyl group having 1 to 6 carbon atoms, a lower alkenyl group having 1 to 6 carbon atoms, or a cycloalkyl group having 3 to 6 carbon atoms. )