JPH0524366A - Heat-sensitive recording sheet - Google Patents

Abstract

PURPOSE:To provide the above h eat-sensitive recording sheet on which a clearly colored writing can be made with the felt pen of an aqueous fluorescent ink and which is also excellent in the preservability of the image thus written. CONSTITUTION:In a heat-sensitive recording sheet provided with a heatsensitive color developing layer consisting mainly of a colorless or plate-colored basic colorless dye and an organic developer, the organic developer contains 4- hydroxy-3-methyl-4'-n-propoxydiphenylsulfone and diphenylsulfone derivative.

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 improved writability with an aqueous highlighter pen.

[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 color developer such as a phenolic compound into fine particles, and then mixing them together to form a binder and filling. A coating liquid obtained by adding agents, sensitivity improvers, lubricants and other auxiliaries to a support such as paper, synthetic paper, plastic film, etc., such as hot pens, thermal heads, hot stamps, laser light, etc. Color recording is obtained by an instant chemical reaction by heating.

These heat-sensitive recording sheets are applied to a wide range of fields such as measurement recorders, computer terminal printers, facsimiles, automatic ticket vending machines, and bar code labels. As a result, the required quality of the thermal recording sheet has become higher. For example, with the increase in recording speed, it is required to obtain a clear color image with high density even with minute heat energy, and on the other hand, light resistance, weather resistance,
A heat-sensitive recording sheet having excellent storage stability such as oil resistance and water resistance is required.

[0004]

On the other hand, as a result of the widespread use of heat-sensitive recording paper recently, there have been many opportunities to retouch using a felt pen of water-based fluorescent ink after heat-sensitive recording. However, since water-based fluorescent ink contains various surfactants, for example, when water-based fluorescent yellow ink is used to write on black color-developing thermosensitive recording paper, the thermosensitive coloring caused by the surfactant is generated. Since the black color of the recording paper and the yellow color of the fluorescent ink are mixed, there is a problem that pure yellow writing cannot be obtained. Furthermore, when written on the recorded image portion, the surfactant contained in the aqueous fluorescent ink causes fading or decoloration of the image portion. The above problem is not limited to yellow, and is the same with other colors.

An object of the present invention is to provide a heat-sensitive recording sheet which is capable of writing in vivid colors using a felt pen made of a water-based fluorescent ink of any color and at the same time excellent in storability of written images.

[0006]

SUMMARY OF THE INVENTION The present invention comprises:
A thermosensitive recording sheet provided with a thermosensitive color developing layer containing a colorless or light-colored basic colorless dye and an organic developer as main components, wherein the thermosensitive color developing layer serves as an organic developer and has the following formula (I):
Of 4-hydroxy-3-methyl-4'-n-propoxydiphenyl sulfone and the diphenyl sulfone derivative represented by the following general formula (II) is contained in the color forming layer to solve the above problems all at once. It has been resolved.

[0007]

[Chemical 3]

[0008]

[Chemical 4]

Specific examples of the diphenylsulfone derivative represented by the above general formula (II) used in the present invention include those represented by the following compound No.

[0010]

[Chemical 5]

[0011]

[Chemical 6]

[0012]

[Chemical 7]

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

In the present invention, a specific 4-hydroxy-3-methyl-4'-n-propoxydiphenyl sulfone is used as a color developing agent, but other color developing agents may be used within a range that does not impair the effects of the present invention. It is also possible to use together. Examples of such developers include bisphenol A, 4-hydroxybenzoic acid esters, 4-hydroxyphthalic acid diesters, phthalic acid monoesters, bis- (hydroxyphenyl) sulfides, 4-hydroxyphenylaryl sulfone. Examples thereof include 4-hydroxyphenylaryl sulfonates, 1,3-di [2- (hydroxyphenyl) -2-propyl] -benzenes, 4-hydroxybenzoyloxybenzoic acid esters, and bisphenol sulfones. 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 isobutyl 4-hydroxybenzoate Acid methylbenzyl

4-hydroxyphthalic acid diesters 4-hydroxyphthalic acid dimethyl 4-hydroxyphthalic acid diisopropyl 4-hydroxyphthalic acid dibenzyl 4-hydroxyphthalic acid 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 monopropyl benzyl ester Phthalic acid monohalogen benzyl ester Phthalic acid monoethoxy 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

4-hydroxyphenyl aryl sulfone
S 4-hydroxy-4'-isopropoxydiphenylsulfone 4-hydroxy-4'-propoxy diphenyl sulfone 4-hydroxy-4'-n-butyl sulfone

4-hydroxyphenylarylsulfona
Over preparative such 4-hydroxyphenyl benzenesulfonate 4-hydroxyphenyl -p- tolyl sulfonate 4-hydroxyphenyl-methylene sulfonate 4-hydroxyphenyl -p-tert-butylbenzene sulfonate 4-hydroxyphenyl -p- isopropoxyphenyl benzene 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 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 β-hydroxybenzoyloxybenzoate Phenyl 4-hydroxybenzoyloxybenzoic acid phenyl 4-hydroxybenzoyloxybenzoic acid α- naphthyl 4-hydroxy-benzoyloxy benzoate β- naphthyl 4-hydroxy-benzoyloxy benzoic acid tert- 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'-hydroxyphenylsulfone 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-butyl Eniru 2'-methyl-4'-hydroxyphenyl sulfone

Bisphenol sulfonic 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

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

When a heat-sensitive recording sheet is formed in the present invention, 1,2-di (3-methylphenoxy) ethane, di (P-methylbenzyl) oxalate, P- are used as sensitizers.
Benzyl biphenyl, β-benzyloxynaphthalene,
It is also possible to use 4-biphenyl P-tolyl ether.

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

Triphenylmethane type leuco dye 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide [also known as crystal violet lactone]

Fluorane type leuco dye 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-qua Lolfluorane 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 based leuco dye 3,6,6'-tris (dimethylamino) spiro [fluorene-9,3'-phthalide] 3,6,6'-tris (diethylamino) spiro [fluorene-9,3'- Phthalide] These dyes can be used alone or in combination of two or more.

In the present invention, as an image stabilizer, 4,4'-butylidene (6-t-butyl-3-methylphenol) 2,2'-di-t-butyl-5,5'-dimethyl-4,
4'-sulfonyldiphenol 1,1,3-tris (2-methyl-4-hydroxy-5)
-Cyclohexylphenyl) butane 1,1,3-tris (2-methyl-4-hydroxy-5)
It is also possible to add -t-butylphenyl) butane and the like.

As the binder used in the present invention, a completely saponified polyvinyl alcohol having a polymerization degree 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, 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, polyacrylic acid ester, polyvinyl butyral, polystyrene and their copolymers, polyamide resin, silicone resin, petroleum resin, terpene resin, ketone resin, and coumarone resin. These polymeric substances are water, alcohol, ketones,
In addition to using it by dissolving it in a solvent such as ester or hydrocarbon,
It can be used in the state of being emulsified or dispersed in a paste in water or another medium and used together depending on the required quality.

The filler used in the present invention is silica,
Inorganic or organic fillers such as calcium carbonate, kaolin, calcined kaolin, diatomaceous earth, talc, titanium oxide, aluminum hydroxide and the like can be mentioned.

In addition, a release agent such as a fatty acid metal salt, a lubricant such as waxes, a benzophenone-based or triazole-based ultraviolet absorber, a water-proofing agent such as glyoxal, a dispersant, and a defoaming agent may be used. it can.

The amounts of the organic developer and the basic colorless dye used in the heat-sensitive recording sheet of 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. Usually, 1 to 8 parts of an organic developer, 0.25 to 3 parts of a diphenyl sulfone compound, and 1 to 20 parts of a filler are used per 1 part of a basic colorless dye, and the binder is a total solid content. 10 to 25% is suitable.

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 the like.

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

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, attritor or sand grinder or an appropriate emulsifying device until the particle diameter becomes several micro or less. Then, the binder and various additives according to the purpose are added to obtain a coating liquid.

Further, an undercoat layer of a polymeric substance containing a filler may be provided below the heat-sensitive layer for the purpose of enhancing color development sensitivity and image storability.

[0042]

Function: Specific developer 4-hydroxy-3 according to the present invention
A thermosensitive recording sheet using -methyl-4'-n-propoxydiphenyl sulfone and a specific diphenyl sulfone derivative does not cause discoloration even by writing with a felt pen of a water-based fluorescent ink, and an image portion is also formed by marking the written image portion. The reason why is not fading or erasing is considered as follows.

When a conventional heat-sensitive recording sheet is written with a felt pen of a water-based fluorescent ink, a developer, a leuco dye, etc. are dissolved in a surfactant contained in the ink for the purpose of improving the storage stability of the ink. .. Along with the vaporization of the surfactant, a color-forming composition in which these color-developing agent and leuco dye are integrated is formed on the writing portion. Therefore, when a yellow ink is used, the yellow color is mixed with the color developed on the thermosensitive recording sheet, resulting in a dull handwritten image.

The heat-sensitive recording sheet of the present invention uses 4-hydroxy-3-methyl-4'-n-propoxydiphenyl sulfone having a specific molecular structure as a developer and has an asymmetric molecular structure sandwiching a sulfone group. A specific diphenyl sulfone derivative having Therefore, the solubility of these materials with respect to the surfactant in the ink becomes extremely low, and the coloring composition is scarcely formed even by vaporization of the surfactant, so that discoloration due to the aqueous fluorescent ink does not occur. Further, even if the colored image portion is marked with an aqueous fluorescent ink, it is considered that fading or decoloring does not occur because the coloring composition is robust to the surfactant in the ink.

[0045]

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 8)] Liquid A (developing agent dispersion liquid) 4-hydroxy-3-methyl-4'-n-propoxydiphenyl sulfone 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 Part Water 11.2 parts Liquid B (dye dispersion) Leuco dye (see Table 1) 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.6 parts Solution C diphenylsulfone derivative (see Table 1) 4. 0 part 10% aqueous polyvinyl alcohol solution 5.0 parts water 3.0 parts Each liquid of the above composition was ground to an average particle size of 1 micron with a sand grinder. Next, the dispersions were mixed at the following ratios to prepare coating solutions.

Liquid A 36.0 parts Liquid B 9.2 parts Liquid C 12.0 parts Kaolin clay (50% dispersion liquid) 12.0 parts Coating amount of each of the above coating liquids on one side of 50 g / m ² base paper 6.0
It was coated and dried so as to be g / m ² , and this sheet was processed 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. 9 to 14) Liquid D (Developer Dispersion Liquid) Developer (see Table 1) 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts water 11.2 Part E liquid (dye dispersion) leuco dye (see Table 1) 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts water 2.6 parts each liquid of the above composition with a sand grinder to an average particle size of 1 micron Ground Then, 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 E 9.2 parts Kaolin clay (50% dispersion liquid) 12.0 parts

Comparative Example 2 (Test Nos. 15 to 16) Liquid A (Developer Dispersion Liquid) 4-Hydroxy-3-methyl-4'-n-propoxydiphenyl sulfone 6.0 parts 10% aqueous polyvinyl alcohol solution 18.8 parts Water 11.2 parts B liquid (dye dispersion) Leuco dye (see Table 1) 2.0 parts 10% aqueous polyvinyl alcohol solution 4.6 parts Water 2.6 parts F liquid diphenyl sulfone derivative (see Table 1) ) 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. Then, 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 A 36.0 parts Liquid B 9.2 parts Liquid F 12.0 parts Kaolin clay (50% dispersion liquid) 12.0 parts

Table 1 shows the results of quality tests conducted on the thermal recording sheets obtained in the above Examples and Comparative Examples.

Note (1) Dynamic color density : A thermal density facsimile UF-1000 manufactured by Matsushita Electric Industrial Co., Ltd. was used, and the image density recorded with an applied energy of 0.58 mj / Dot and a pulse width of 0.97 milliseconds was measured by a Macbeth densitometer ( RD-914, amber filter used, same hereafter).

Note (2) Writable uncolored part of water-based fluorescent pen: Mitsubishi water-based fluorescent pen (trade name: underline US-80 green) was used to write on the uncolored part of the thermal paper sample, and the original The degree of discoloration with respect to green was visually measured after 3 weeks. ○: No color change △: Color change ×: Significant color change

Image area: The image area printed by the method of Note (1) was marked with the above-mentioned aqueous fluorescent pen, and the degree of decoloring of the image after 3 weeks was visually measured. ○: No erasing at all △: Very erasing ×: Completely erasing

Note (3) Weather resistance : The thermal paper sample printed by the method of Note (1) was subjected to 24 hours under the conditions of 40 ° C. and 90% RH.
Let stand for a while and measure the image density with a Macbeth densitometer The residual rate was calculated by the following formula. Residual rate = (image density after processing / unprocessed image density) × 1
00

[0054]

[Table 1]

[0055]

[Table 2]

In Table 1 above, for the leuco dye, the symbol A
Is 2- (4-oxa-hexyl) -3-diethylamino-6-methyl-7-anilinofluorane, and the symbol B is 2-
(4-oxa-hexyl) -3-dimethylamino-6-
Methyl-7-anilinofluorane, symbol C is 3-n-dibutylamino-6-methyl-7-anilinofluorane,
The symbol D is 3- (N-methyl-N-propylamino) -6.
-Methyl-7-anilinofluorane.

[0057]

The effects of the present invention are as follows. (1) The heat-sensitive recording sheet according to the present invention does not cause discoloration or decolorization of an image when writing with a felt pen of a water-based fluorescent ink, and therefore, these writing tools can be used to write freely on the heat-sensitive recording sheet. It became possible to do. (2) It is excellent in storage stability of images, so it can be sufficiently used under severe conditions.

Claims (1)

Claim: What is claimed is: 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. The layer contains 4-hydroxy-3-methyl-4'-n-propoxydiphenyl sulfone of the following formula (I) as an organic developer, and diphenyl sulfone represented by the following general formula (II) in the color developing layer. A heat-sensitive recording sheet comprising a derivative. [Chemical 1] [Chemical 2]