JPH08290670A - Thermal recording body - Google Patents

Abstract

PURPOSE: To provide a thermal recording body having excellent record sensitivity and preservative property with time of recorded images, and excellent light resistance and water resistance. CONSTITUTION: In a thermal recording body having a recording layer which contains a colorless or light color basic dye and a coloring agent arranged on a support body, the recording layer contains a 3-p- dimethylaminophenylamino,-5,7-dimethylfluoran, 4,4'-isopropylidene diphenol and 1,1,3-tris(2-methyl-4-hydroxy-5-cyclohexylphenyl)butane.

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 material utilizing a coloring reaction between a colorless or light-colored basic dye and a color developing agent, and particularly to recording sensitivity and storage stability of recorded images with time, light resistance and water resistance. The present invention relates to a thermosensitive recording material having excellent properties.

[0002]

2. Description of the Related Art A heat-sensitive recording material which utilizes a color reaction between a colorless or light-colored basic dye and an organic or inorganic color-forming agent to bring both color-forming substances into contact with each other by heat to obtain a recorded image is often used. Are known. Since such a thermal recording medium is relatively inexpensive, the recording device is compact, and its maintenance is easy, it is used not only as a recording medium for facsimiles and various computers but also in a wide range of fields.

For example, as one of the fields of use thereof, a thermal recording material having strong absorption in the near infrared region at the time of color development is used as a label for displaying products with the expansion of POS (Point of sales) system in retail stores and the like. The number of cases used as is increasing. The thermal recording material for labels attached to products is often exposed to indoor light or sunlight for a long period of time, and as a result, the background part may turn yellow and the product image may be significantly impaired. is there. Therefore, there is a demand for a heat-sensitive recording material that causes less yellowing of the background portion when exposed to room light or sunlight.

Conventionally, there has been proposed a method of adding a finely pulverized UV absorber to a recording layer or a protective layer in order to prevent yellowing of the background portion of a thermosensitive recording medium due to light. UV absorbers have poor UV absorption efficiency, so a small amount cannot be used to obtain sufficient effects. On the other hand, a large amount used in the recording layer causes background fog or a new defect such as a decrease in recording density. Under the present circumstances, the light resistance is not sufficiently obtained as a result.

Further, a heat-sensitive recording material using a microcapsule containing a hydrophobic medium, a colorless or light-colored basic dye and an ultraviolet absorber is disclosed in JP-A-61-283589 and JP-A-61-283590. , JP-A-61-1
No. 213,591 and Japanese Patent Laid-Open No. 63-230387, the basic dye in the microcapsules is dissolved in a hydrophobic medium, so that it is more yellowed by light exposure than the basic dye in the solid state. It is easily discolored. Therefore, even if the hydrophobic medium, the basic dye and the ultraviolet absorber are included in the microcapsules, when the irradiation amount of light increases, a coloring phenomenon appears and a sufficient satisfactory ultraviolet absorber effect is obtained. Absent.

Further, a thermosensitive recording medium using 3-p-dimethylaminophenylamino-5,7-dimethylfluorane as a basic dye having strong absorption in the near infrared region at the time of color development is disclosed in JP-A-64-69382. However, particularly in the case of using inexpensive 4,4′-isopropylidenediphenol as a color developing agent, the storability of the recorded image with time and the water resistance of the recorded image (the recorded image portion is dipped in water) are described. There is a problem in the retention of the recording density).

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a thermosensitive recording medium which is excellent in recording sensitivity, storage stability of recorded images with time, light resistance and water resistance.

[0008]

SUMMARY OF THE INVENTION The present invention comprises:
In a thermosensitive recording medium provided with a recording layer containing a colorless or light-colored basic dye and a coloring agent, 3--
Contain p-dimethylaminophenylamino-5,7-dimethylfluorane, 4,4'-isopropylidenediphenol and 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane As a result, the above problems have been resolved and completed.

[0009]

In the present invention, 3-p-dimethylaminophenylamino-5,7- is used as a colorless or pale basic dye.
Although a specific basic dye such as dimethylfluorane is used, such a specific basic dye causes little deterioration in light resistance of the background part and the recording part, but has a problem in recording sensitivity, storability of recorded image and water resistance. There is. However, such a specific basic dye uses 4,4'-isopropylidenediphenol as a coloring agent, and further, 1,1,3-tris (2-methyl-) which is a hindered phenol compound.
It has been found that by using 4-hydroxy-5-cyclohexylphenyl) butane together, a thermosensitive recording medium having excellent water resistance of the recorded image and high recording sensitivity can be obtained.

A specific basic dye, 3-p-dimethylaminophenylamino-5,7-dimethylfluorane, is used in the recording layer, but other basic dyes may be used as long as they do not impair the desired effects of the present invention. Various known colorless or pale basic dyes can be used in combination, for example, 3,3-bis (p-
Dimethylaminophenyl) -6-dimethylaminophthalide, 3- (4-diethylamino-2-methylphenyl)
-3- (4-Dimethylaminophenyl) -6-dimethylaminophthalide, 3-diethylamino-7-anilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-6-methyl-7 -Chlorofluorane, 3-diethylamino-7-chlorofluorane, 3-di (n-butyl) amino-6-methyl-7
-Anilinofluorane, 3- (N-ethyl-N-isoamyl) amino-6-methyl-7-anilinofluorane,
3- (N-methyl-N-cyclohexyl) amino-6-
Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-di (n-
Butyl) amino-7- (o-chloroanilino) fluorane, 3-di (n-pentyl) amino-6-methyl-7-
Anilinofluorane, 3-diethylamino-7- (o-
Chlorophenylamino) fluorane, 3-diethylamino-7- (o-fluorophenylamino) fluorane,
3- (N-ethyl-p-toluidino) -6-methyl-7
-Anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-6-chloro-7-anilinofluorane, 3- ( N-methyl-N-n-propylamino) -6-methyl-7-anilinofluorane, 3
-Dimethylamino-6-methyl-7-anilinofluorane, 3-di (n-butyl) amino-6-methyl-7-m
-Toluidinofluorane, 3- (Nn-hexyl-N)
-Ethyl) amino-6-methyl-7-anilinofluorane, 3- (N-ethyl-N-isobutyl) amino-6-
Methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-p-ethoxyanilinofluorane,
3-pyrrolidino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 2,2-bis {4- [6 '-(N-cyclohexyl-N-methyl Amino) -3'-methylspiro [phthalide-3,9'-xanthen-2'-ylamino] phenyl} propane, 3-diethylamino-7- (3'-trifluoromethylphenyl) aminofluorane, 3,3-
Bis [1- (4-methoxyphenyl) -1- (4-dimethylaminophenyl) ethylene-2-yl] -4,5
6,7-Tetrachlorophthalide, 3-p- (p-dimethylaminoanilino) anilino-6-methyl-7-chlorofluorane, 3-p- (p-chloroanilino) anilino-6-methyl-7- Chlorofluorane, 3,6-bis (dimethylamino) fluorene-9-spiro-3'-
(6'-Dimethylamino) phthalide and the like can be mentioned. Of course, it is not limited to these, and two or more kinds may be used in combination as required.

4, as a coloring agent together with a specific basic dye
Although 4'-isopropylidene diphenol is used, various other known colorants can be used in combination as long as the desired effects of the present invention are not impaired. Specific examples of such a coloring agent include, for example, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, 4,4′-
Cyclohexylidene diphenol, hydroquinone monobenzyl ether, benzyl 4-hydroxybenzoate,
4,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone,
2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4'-methyldiphenyl sulfone, 4-hydroxyphenyl-4'-benzyloxyphenyl sulfone, 3,4-dihydroxyphenyl-4'-methylphenyl sulfone, 1,4 -Bis [α-methyl-α- (4 '
-Hydroxyphenyl) ethyl] benzene, 1,3-bis [α-methyl-α- (4'-hydroxyphenyl) ethyl] benzene, 2,2'-thiobis (4-tert-octylphenol), and other phenolic compounds, N, N'-
Thiourea compounds such as di-m-chlorophenylthiourea, N- (p-toluenesulfonyl) carbamoyl acid-
p-cumylphenyl ester, N- (p-toluenesulfonyl) carbamoyl acid-p-benzyloxyphenyl ester, N- (o-toluoyl) -p-toluenesulfoamide, N- (p-toluenesulfonyl) -N '. −
(P-tolyl) urea having a —SO ₂ NH— bond in the molecule, zinc 4- [2- (p-methoxyphenoxy) ethyloxy] salicylate, 4- [3- (p-tolylsulfonyl) propyloxy ] Zinc salicylate, 5-
Examples include zinc salts of salicylic acid derivatives such as [p- (2-p-methoxyphenoxyethoxy) cumyl] salicylic acid zinc.

The use ratio of the specific basic dye and the color developing agent is not particularly limited, but the basic dye 1 is generally used.
About 1 to 5 parts by weight, and preferably about 2 to 3 parts by weight, of a coloring agent is used.

A sensitizer may be used in the recording layer in order to enhance recording sensitivity. For example, stearic acid amide, ethylenebisstearic acid amide, methylenebisstearic acid amide, N-methylolstearic acid amide, dibenzyl terephthalate. , Benzyl p-benzyloxybenzoate, phenyl 1-hydroxy-2-naphthoate, 2-naphthylbenzyl ether, m-terphenyl, p-benzylbiphenyl, p-tolylbiphenyl ether, di (p-methoxyphenoxyethyl) ether. , 1,2-
Di (3-methylphenoxy) ethane, 1,2-di (4-
Methylphenoxy) ethane, 1,2-di (4-methoxyphenoxy) ethane, 1,2-diphenoxyethane,
1,4-di (phenylthio) butane, p-acetophenetizide, N-acetoacetyl-p-toluidine, di (β
-Biphenylethoxy) benzene, p-di (vinyloxyethoxy) benzene, 1-isopropylphenyl-2
-Phenylethane, dibenzyl oxalate, dioxalate-
Examples thereof include p-chlorobenzyl ester and oxalic acid di-p-methylbenzyl ester.

In order to improve the storability of a recorded image, 1,1,3-tris (2-methyl-4-hydroxy-5-cyclohexylphenyl) butane is used as a storability improver in the recording layer. Although the amount used is not particularly limited, it is preferably used in the range of 10 to 200% by weight based on the basic dye. Further, it can be used in combination with other various known storage improvers, for example, 2,2'-methylenebis (4-methyl-6-tert-butylphenol), 2,2'-methylenebis (4-ethyl-6-). tert-butylphenol),
2,2'-ethylidene bis (4,6-di-tert-butylphenol), 4,4'-thiobis (2-methyl-6-
tert-butylphenol), 4,4′-butylidene bis (6-tert-butyl-m-cresol), 1- [α-methyl-α- (4′-hydroxyphenyl) ethyl] -4
-[Α ', α'-bis (4 "-hydroxyphenyl) ethyl] benzene, 1,1,3-tris (2-methyl-4)
-Hydroxy-5-tert-butylphenyl) butane,
4,4'-thiobis (3-methylphenol), 4,
4'-dihydroxy-3,3 ', 5,5'-tetrabromodiphenyl sulfone, 4,4'-dihydroxy-3,
3 ', 5,5'-tetramethyldiphenyl sulfone,
2,2-bis (4-hydroxy-3,5-dibromophenyl) propane, 2,2-bis (4-hydroxy-3,
5-dichlorophenyl) propane, 2,2-bis (4-
Hindered phenol compounds such as hydroxy-3,5-dimethylphenyl) propane, 1,4-diglycidyloxybenzene, 4,4′-diglycidyloxydiphenyl sulfone, 4-benzyloxy-4 ′-(2-methylglycidyl) (Oxy) diphenyl sulfone, diglycidyl terephthalate, cresol novolac type epoxy resin,
Epoxy compounds such as phenol novolac type epoxy resin and bisphenol A type epoxy resin, N, N'-di-
2-naphthyl-p-phenylenediamine, sodium or polyvalent metal salt of 2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate, bis (4-ethyleneiminocarbonylaminophenyl) methane and the like can be mentioned. To be

The recording layer coating liquid containing these substances generally uses water as a dispersion medium, and disperses the dye and the colorant together or separately by an agitator / pulverizer such as a ball mill, attritor or sand mill. And then prepared.

In the coating liquid, starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy modified polyvinyl alcohol, acetoacetyl group modified polyvinyl alcohol, silicon modified polyvinyl alcohol, etc. Diisobutylene / maleic anhydride copolymer salt, styrene /
Maleic anhydride copolymer salt, ethylene / acrylic acid copolymer salt, styrene / acrylic acid copolymer salt, styrene /
At least one kind of butadiene copolymer emulsion, urea resin, melamine resin, amide resin, polyurethane resin and the like is blended in the range of about 5 to 30% by weight based on the total solid content of the recording layer.

If desired, various auxiliary agents can be added to the coating solution. For example, dispersants such as sodium dioctylsulfosuccinate, sodium dodecylbenzenesulfonate, sodium lauryl alcohol sulfate, and fatty acid metal salts. , Titanium oxide, diatomaceous earth, particulate anhydrous silica, inorganic pigments such as activated clay, styrene microballs, nylon powder, polyethylene powder, urea / formalin resin filler, organic pigments such as raw starch particles, zinc stearate, calcium stearate, polyethylene Waxes such as wax, carnauba wax, paraffin wax, and ester wax, defoaming agents, coloring dyes, etc. are appropriately added.

In the heat-sensitive recording material of the present invention, a protective layer may be provided on the recording layer for the purpose of improving the storability of a recorded image with respect to chemicals such as plasticizers and oils, or recording suitability. The liquid generally uses water as a dispersion medium and a binder such as starch, hydroxyethyl cellulose, methyl cellulose, carboxymethyl cellulose, gelatin, casein, gum arabic, polyvinyl alcohol, carboxy modified polyvinyl alcohol, acetoacetyl group modified polyvinyl alcohol, and silicon modified polyvinyl alcohol. It is prepared by mixing and stirring pigments such as kaolin, light calcium carbonate and fine particle silica.

Further, in the protective layer coating liquid, lubricants such as zinc stearate, calcium stearate, polyethylene wax, carnauba wax, paraffin wax and ester wax, and surfactants such as sodium dioctylsulfosuccinate (dispersion) may be added, if necessary. Agent, wetting agent), defoaming agent,
Various auxiliaries such as water-soluble polyvalent metal salts such as potassium alum and aluminum acetate may be appropriately added. Further, in order to further improve the water resistance, glyoxal, boric acid,
A curing agent such as dialdehyde starch or an epoxy compound can also be used in combination.

The method for forming the recording layer and the protective layer is not particularly limited, and suitable coating such as air knife coating, varibar blade coating, pure blade coating, rod blade coating, short dwell coating, curtain coating, die coating, etc. The coating liquid for recording layer is applied and dried on the support by a method, and then the coating liquid for protective layer is further applied and dried on the recording layer. The support may be appropriately selected from paper, plastic film, synthetic paper, non-woven fabric, metal deposit, etc., and used. Also,
The coating amount of the recording layer coating liquid is ² to 12 g / m ^{2 as} a dry weight,
Preferably 3 to 10 g / m ² approximately, 0.5 to 15 g / m ² coating amount of the protective layer coating liquid for a dry weight, preferably 1.
It is adjusted within the range of 0 to 8 g / m ² .

If necessary, a protective layer may be provided on the back side of the thermosensitive recording medium to further improve the storage stability, or a layer containing an ionizing radiation curable resin may be provided as the uppermost layer to give a strong gloss. It is possible. Further, an undercoat layer may be provided between the support and the recording layer, smoothing treatment such as super calendering may be applied after coating each layer, or an adhesive label may be applied to the back surface of the recording material to form an adhesive label. Various known techniques in the field of producing a heat-sensitive recording material, such as a rewetting adhesive layer, a magnetic recording layer, a printing coating layer, and a thermal transfer recording layer, can be added as necessary.

[0022]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, the part and% in an example show a weight part and weight%, respectively.

Example 1 Preparation of solution A 30 parts of 1,2-di (3-methylphenoxy) ethane, 40 parts of a 10% aqueous solution of polyvinyl alcohol [Goseiran L-3266, manufactured by Nippon Synthetic Chemical Industry Co., Ltd.], and Water 30
Of the composition was dispersed in a vertical sand mill (manufactured by IMEX Co., Ltd.) until the particle size became 1.3 μm.

Preparation of Solution B A composition comprising 30 parts of 3-p-dimethylaminophenylamino-5,7-dimethylfluorane, 10 parts of a 5% aqueous solution of methylcellulose and 60 parts of water has a mean particle diameter of 1 μm in a sand mill. Crushed until.

Preparation of Solution C A composition consisting of 30 parts of 4,4′-isopropylidene diphenol, 5 parts of a 5% aqueous solution of methylcellulose and 70 parts of water was pulverized by a sand mill until the average particle diameter became 2 μm.

Preparation of Solution D 1,1,3-Tris (2-methyl-4-hydroxy-5)
A composition consisting of 30 parts of -cyclohexylphenyl) butane, 5 parts of a 5% aqueous solution of methylcellulose, and 65 parts of water was pulverized with a sand mill until the average particle size became 1 µm.

Formation of Undercoat Layer Baked kaolin (trade name: Ansilex, manufactured by EMC,
Oil absorption 140 ml / 100 g) 80 parts, light calcium carbonate 20 parts, polyvinyl alcohol 10% aqueous solution 50
Parts, 20 parts of styrene-butadiene latex having a solid concentration of 45%, 40% aqueous solution of sodium polyacrylate 1
Part of the composition was mixed and stirred to obtain a coating liquid having a basis weight of 62 g on one side of a neutral paper, and the coating amount after drying was 7 g / m ²
Was applied, dried, and supercalendered to form an undercoat layer.

Formation of Recording Layer 50 parts of A solution, 25 parts of B solution, 50 parts of C solution, 30 parts of D solution, 170 parts of 10% aqueous solution of polyvinyl alcohol, 3 parts of 40% aqueous solution of glyoxal and 2 parts of aluminum hydroxide
A coating solution obtained by mixing and stirring 0 parts of the above was coated and dried on the above-mentioned undercoat layer so that the coating amount after drying was 5 g / m ^2, and a recording layer was provided.

Formation of Protective Layer 195 parts of a 10% aqueous solution of polyvinyl alcohol modified with acetoacetyl group, 40 parts of aluminum hydroxide having an average particle size of 1.0 μm, kaolin [trade name: UW-90, manufactured by EMC] 10 parts, stearin 16 parts of 30% zinc oxide dispersion,
Curing agent with a concentration of 30% [Product name: PA-800, Japan PM
Co., Ltd.] A coating solution for a protective layer obtained by mixing and stirring a composition of 0.7 part and 100 parts of water was applied onto the recording layer so that the coating amount after drying was 4 g / m ^2. After drying, a super calender treatment was performed to obtain a heat sensitive recording material.

Example 2 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that D liquid 15 was used instead of 30 parts of D liquid in the formation of the recording layer of Example 1.

Example 3 A thermosensitive recording medium was obtained in the same manner as in Example 1 except that D liquid 50 was used instead of 30 parts of D liquid in the formation of the recording layer of Example 1.

Comparative Example 1 In the preparation of solution D, 1,1,3-tris (2-methyl-)
4-hydroxy-5-cyclohexylphenyl) butane was replaced by 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl), except that
A thermal recording material was obtained in the same manner as in Example 1.

Comparative Example 2 In preparation of solution B, 3- (N) was used instead of 3-p-dimethylaminophenylamino-5,7-dimethylfluorane.
A thermosensitive recording medium was obtained in the same manner as in Example 1 except that -ethyl-N-isoamylamino) -6-methyl-7anilinofluorane was used.

Comparative Example 3 In preparation of solution B, 3-di (n-butyl) amino-6-methyl-7-anilinofluorane was used in place of 3-p-dimethylaminophenylamino-5,7-dimethylfluorane. A thermosensitive recording medium was obtained in the same manner as in Example 1 except that was used.

Comparative Example 4 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that 4-hydroxy-4'-isopropoxydiphenyl sulfone was used in place of 4,4'-isopropylidenediphenol in the preparation of solution C. Got

Comparative Example 5 A thermosensitive recording medium was prepared in the same manner as in Example 1 except that 30 parts of 4,4'-dihydroxydiphenyl sulfone was used in place of 4,4'-isopropylidenediphenol in the preparation of solution C. Obtained.

The heat-sensitive recording material thus obtained was subjected to the following evaluation tests, and the results are shown in Table 1.

[Coloring property] Heat-sensitive evaluation machine [Product name: TH-P
MD, Okura Electric Co., Ltd.] applied energy 0.50 mJ
Each of the thermosensitive recording materials was made to develop color at a dot / dot, and the color density of the obtained recorded image was measured in a visual mode with a Macbeth densitometer [RD-914 type, manufactured by Macbeth Co.].

[Light resistance] The initial density of the background portion of the thermosensitive recording medium after recording in the above [Coloring property] and the background portion after irradiation with a xenon fade meter (manufactured by Suga Test Instruments Co., Ltd.) for 14 hours (xenon arc) The density was measured with a Macbeth densitometer (using a blue filter).

[High heat resistance] The heat-sensitive recording material after recording in the above [color development] was left at 80 ° C. for 24 hours, and the color density and background density were measured with a Macbeth densitometer (visual mode). The high heat resistance was evaluated.

[Water resistance] The thermosensitive recording medium after recording according to the above [Coloring property] was immersed in tap water at 20 ° C. for 24 hours, and the color density was measured with a Macbeth densitometer (visual mode) to obtain water resistance. The sex was evaluated.

[0042]

[Table 1]

[0043]

As is clear from the results of [Table 1], the present invention is a thermosensitive recording medium which is particularly excellent in recording sensitivity, storage stability of recorded images with time, light resistance and water resistance.

Claims (1)

[Claims] 1. A thermosensitive recording medium comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent, wherein 3-p-dimethylaminophenylamino-5,5 is contained in the recording layer. 7-Dimethylfluorane, 4,4'-isopropylidenediphenol and 1,1,3-tris (2-
A heat-sensitive recording material containing methyl-4-hydroxy-5-cyclohexylphenyl) butane.