JP2002362036A - Heat-sensitive recording material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a high-quality heat-sensitive recording material which is almost free from a texture fog and shows outstanding color development properties and shelf stability. SOLUTION: The heat-sensitive recording material has a heat-sensitive color developing layer containing a normally colorless or a pale-color color developing chemical compound, a developing chemical compound which thermally develops a color in the color developing chemical compound and a sensitizer as main components, formed on a support. The developing chemical compound is shown in formula (1) (wherein, n is 2 to 10). The sensitize is a dibenzoylmethane.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a heat-sensitive recording material. More specifically, it has high sensitivity and low background fog,
The present invention relates to a heat-sensitive recording material having excellent image storability.

[0002]

2. Description of the Related Art Generally, a thermosensitive recording material is prepared by separately dispersing a developer such as a leuco dye and a phenolic substance into fine particles, and then mixing the two with a binder, a sensitizer, a filler, Additives such as lubricants to make a coating liquid, applied to paper, film, synthetic paper, etc., and record the color by the chemical reaction that occurs when one or both of the leuco dye and the developer are melted and contacted by heating Is what you get. For color development of the heat-sensitive recording sheet, a thermal printer or the like having a built-in thermal head is used. Compared with other recording methods, this thermal recording method is (1) no noise during recording, (2) there is no need for development and fixing, (3) maintenance-free, (4) machine is relatively inexpensive. With features such as
Facsimile field, computer output, printer field such as calculator, medical measurement recorder field,
It is widely used in the field of automatic ticket vending machines, the field of thermal recording labels and the like.

[0003] In recent years, the use of POS systems in retail stores and supermarkets, and automated transportation systems has increased the use of labels, tickets, coupons, and the like. In these applications, it is desired that the heat-sensitive recording material is further improved in storage stability. The demand for high-speed recording has further increased, and there has been a strong demand for the development of heat-sensitive recording materials that can sufficiently cope with high-speed recording. However, the drawback that background fogging generally occurs when the sensitivity of heat-sensitive recording materials is increased to improve thermal response. Is easy to appear. Conventionally, various methods have been proposed to improve the heat responsiveness and further improve the storage stability, but none of them are satisfactory.

[0004]

The object of the present invention is as described above.
It is to solve the disadvantages of the prior art. That is, it is an object of the present invention to provide a heat-sensitive recording material having high sensitivity, little background fog, and excellent image storability.

[0005]

The present inventor has made various studies to achieve the above object, and as a result, completed the present invention. That is, the present invention provides (1) a heat-sensitive color-forming layer containing, as main components, a colorless compound which is usually colorless or pale, a color-developing compound capable of forming a color when heated, and a sensitizer. In the heat-sensitive recording material, the following formula (1)

[0006]

Embedded image

(In the formula (1), n = 2 to 10 is represented.)
A heat-sensitive recording material containing dibenzoylmethane as a sensitizer.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the present invention, a colorless or pale-colored color-forming compound, a compound represented by the formula (1) as a color developing compound, and dibenzoylmethane as a sensitizer are used as main components. Then, a thermosensitive coloring layer is prepared by using a binder and other fillers and other additives as necessary.

In forming the thermosensitive color-forming layer in the present invention, the color-forming compound is usually from 1 to 50% by weight, preferably from 5 to 30% by weight, and the compound represented by the formula (1) is usually from 1 to 50% by weight.
80% by weight, preferably 5 to 40% by weight, dibenzoylmethane is usually 0.5 to 80% by weight, preferably 5 to 40% by weight.
%, The binder is usually 1 to 90% by weight, and the filler is usually 0%.
To 80% by weight, and other lubricants, surfactants, defoamers, ultraviolet absorbers and the like are each in an arbitrary ratio, for example, each is usually 0 to 80% by weight.
30% by weight is used (% by weight is the weight ratio of each component in the thermosensitive coloring layer). As a more preferred embodiment, among the above compositions, the compound represented by the formula (1) is used in an amount of 0.5 to 20 times, preferably 0.5 to 20 times, in terms of weight ratio, of the chromogenic compound 1. 1 to 5 times, dibenzoylmethane is usually 0.5 to 20 times, preferably 1 to 8 times. Further, in the heat-sensitive recording material of the present invention, a known color developing compound or a sensitizer other than the main component of the present invention may be used in combination.

The compound represented by the formula (1) used in the present invention can be produced by the method described in WO 99/51444, and 2,2-bis (hydroxymethyl) -1,3 -A dehydration condensation product of a polycondensation product of propanediol and 4-hydroxybenzoic acid (C
AS No. 92881-24-8). Equation (1)
N is preferably 4 to 6, and more preferably 5.

The color-forming compound used in the present invention is not particularly limited as long as it is generally used for pressure-sensitive recording paper or heat-sensitive recording paper. Examples of color-forming compounds that can be used include, for example, fluoran compounds, triarylmethane compounds, spiro compounds, diphenylmethane compounds, thiazine compounds, lactam compounds,
Fluorene compounds and the like.

Specific examples of fluoran compounds that can be used include, for example, 3-diethylamino-6-methyl-7-anilinofluoran, 3-dibutylamino-6-methyl-
7-anilinofluoran, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isopentylamino)-
6-methyl-7-anilinofluoran, 3- (N-ethyl-N-isobutylamino) -6-methyl-7-anilinofluoran, 3- [N-ethyl-N- (3-ethoxypropyl) Amino] -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-hexylamino) -6
Methyl-7-anilinofluoran, 3-dipentylamino-6-methyl-7-anilinofluoran, 3- (N-
Methyl-N-propylamino) -6-methyl-7-anilinofluoran, 3- (N-ethyl-N-tetrahydrofurylamino) -6-methyl-7-anilinofluoran, 3-diethylamino-6 Methyl-7- (p-chloroanilino) fluoran, 3-diethylamino-6-methyl-7- (p-fluoroanilino) fluoran, 3-
[N-ethyl-N- (p-tolyl) amino] -6-methyl-7-anilinofluoran, 3-diethylamino-6
-Methyl-7- (p-toluidino) fluoran, 3-diethylamino-7- (o-chloroanilino) fluoran, 3-dibutylamino-7- (o-chloroanilino)
Fluorane, 3-diethylamino-7- (o-fluoroanilino) fluoran, 3-dibutylamino-7- (o
-Fluoroanilino) fluoran, 3-diethylamino-7- (m-trifluoromethylanilino) fluoran, 3-diethylamino-7- (3,4-dichloroanilino) fluoran, 3-pyrrolidino-6-methyl-7 −
Anilinofluoran, 3-diethylamino-6-chloro-7-ethoxyethylaminofluoran, 3-diethylamino-6-chloro-7-anilinofluoran, 3-diethylamino-7-chlorofluoran, 3-diethylamino- 7-methylfluoran, 3-diethylamino-7
-Octylfluoran, 3- [N-ethyl-N- (p-
Tolyl) amino] -6-methyl-7-phenethylfluoran and the like.

Specific examples of triarylmethane compounds that can be used include, for example, 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide (also known as crystal violet lactone or CVL),
3,3-bis (p-dimethylaminophenyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,
2-dimethylaminoindol-3-yl) phthalide,
3- (p-dimethylaminophenyl) -3- (2-methylindol-3-yl) phthalide, 3- (p-dimethylaminophenyl) -3- (2-phenylindole-
3-yl) phthalide, 3,3-bis (1,2-dimethylindol-3-yl) -5-dimethylaminophthalide, 3,3-bis (1,2-dimethylindole-3-
Yl) -6-dimethylaminophthalide, 3,3-bis (9-ethylcarbazol-3-yl) -5-dimethylaminophthalide, 3,3- (2-phenylindole-
3-yl) -5-dimethylaminophthalide, 3-p-dimethylaminophenyl-3- (1-methylpyrrole-2
-Yl) -6-dimethylaminophthalide and the like.

Specific examples of further usable spiro compounds include, for example, 3-methylspirodinaphthopyran, 3-ethylspirodinaphthopyran, 3,3'-dichlorospirodinaphthopyran and 3-benzylspirodinaphthopyran ,
3-propylspirobenzopyran, 3-methylnaphtho-
Specific examples of diphenylmethane compounds include (3-methoxybenzo) spiropyran, 1,3,3-trimethyl-6-nitro-8'-methoxyspiro (indoline-2,2'-benzopyran) and the like. Halophenyl-leuco auramine, 4,4-bis-dimethylaminophenylbenzhydryl benzyl ether, N-2,4
5-trichlorophenyl leuco auramine and the like are specific examples of thiazine compounds, such as benzoyl leucomethylene blue and p-nitrobenzoyl leu methylene blue. Specific examples of lactam compounds are, for example, rhodamine B anilino lactam and rhodamine. Bp-
Chloroanilinolactam and the like are specific examples of fluorene-based compounds, for example, 3,6-bis (dimethylamino)
Fluorene spiro (9,3 ')-6'-dimethylaminophthalide, 3,6-bis (dimethylamino) fluorene spiro (9,3')-6'-pyrrolidinophthalide, 3-
Dimethylamino-6-diethylaminofluorenespiro (9,3 ')-6'-pyrrolidinophthalide and the like. These coloring compounds are used alone or in combination.

In the present invention, a color developing compound other than the compound represented by the formula (1) can be used in combination. Examples of such a color developing compound are generally pressure-sensitive recording paper and heat-sensitive recording paper. What is necessary is just what is used for it, and it does not specifically limit. For example, α-naphthol, β-naphthol,
p-octylphenol, 4-t-octylphenol, pt-butylphenol, p-phenylphenol, 1,1-bis (p-hydroxyphenyl) propane, 2,2-bis- (p-hydroxyphenyl) propane (alias: Bisphenol A or BPA), 2,2-bis- (p-hydroxyphenyl) butane, 1,1-bis- (p-hydroxyphenyl) cyclohexane, 4,
4'-thiobisphenol, 4,4'-cyclo-hexylidenediphenol, 2,2'-bis- (2,5-dibromo-4-hydroxyphenyl) propane, 4,4'-
Isopropylidenebis (2-t-butylphenol),
2,2′-methylenebis (4-chlorophenol),
4,4′-dihydroxydiphenyl sulfone, 2,4 ′
-Dihydroxydiphenylsulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, 4-hydroxy-4′-isopropocodidiphenylsulfone, bis (4
Phenolic compounds such as -hydroxyphenyl) methyl acetate, butyl bis (4-hydroxyphenyl) acetate, and benzyl bis (4-hydroxyphenyl) acetate; benzyl p-hydroxybenzoate; ethyl p-hydroxybenzoate; 4-hydroxyphthalate Dibenzyl acid, dimethyl 4-hydroxyphthalate, ethyl 5-hydroxyisophthalate, 3,5-di-t-butylsalicylic acid, 3.5-di-
Aromatic carboxylic acid derivatives such as α-methylbenzylsalicylic acid, aromatic carboxylic acids and polyvalent metal salts thereof, and the like, include those generally used for pressure-sensitive recording paper and heat-sensitive recording paper, but are not limited thereto. Not done.

In the present invention, a sensitizer (a heat-fusible compound) other than dibenzoylmethane can be used in combination. Examples of such a sensitizer (a heat-fusible compound) include animals and plants. Wax, waxes such as synthetic waxes, higher fatty acids, higher fatty acid amides, higher fatty acid anilides, naphthalene derivatives, aromatic ethers, aromatic carboxylic acid derivatives, aromatic sulfonic acid ester derivatives, carbonic acid or oxalic acid diester derivatives, biphenyl derivatives, A terphenyl derivative, a sulfone derivative, or the like that is solid at room temperature and has a melting point of about 70 ° C. or more can be used.

Specific examples of the waxes that can be used in combination include:
For example, wood wax, carnauba wax, shellac, paraffin, montan wax, oxidized paraffin, polyethylene wax, polyethylene oxide, etc., as specific examples of higher fatty acids, for example, stearic acid, behenic acid, etc., as specific examples of higher fatty acid amides For example, stearic acid amide,
Oleic acid amide, N-methylstearic acid amide, erucic acid amide, methylolbehenic acid amide, methylenebisstearic acid amide, ethylenebisstearic acid amide, etc. are specific examples of higher fatty acid anilides, for example, stearic acid anilide, linoleic acid Specific examples of the naphthalene derivative include anilide and the like, for example, 1-benzyloxynaphthalene, 2-benzyloxynaphthalene, 1-benzyloxynaphthalene,
Specific examples of aromatic ethers such as hydroxynaphthoic acid phenyl ester include 1,2-diphenoxyethane, 1,4-diphenoxybutane, 1,2-bis (3-methylphenoxy) ethane, 1,2 -Screw (4-
Methoxyphenoxy) ethane, 1,2-bis (3,4-
Dimethylphenyl) ethane, 1-phenoxy-2- (4
-Chlorophenoxy) ethane, 1-phenoxy-2-
Specific examples of aromatic carboxylic acid derivatives such as (4-methoxyphenoxy) ethane and the like include, for example, benzyl p-hydroxybenzoate, benzyl p-benzyloxybenzoate, dibenzyl terephthalate, etc. Specific examples of acid ester derivatives include, for example, p-toluenesulfonic acid phenyl ester,
Phenylmesitylenesulfonate, 4-methylphenylmesitylenesulfonate and the like are specific examples of carbonic acid or oxalic acid diester derivatives, for example, diphenyl carbonate,
Examples of biphenyl derivatives include dibenzyl oxalate, di (4-chlorobenzyl) oxalate, and di (4-methylbenzyl) oxalate. Specific examples of the biphenyl derivative include p-benzylbiphenyl and p-allyloxybiphenyl. However, specific examples of the terphenyl derivative include, for example, m-terphenyl, and examples of the sulfone derivative include, for example, diphenyl sulfone.

The amounts of the color developing compound and the sensitizer which can be used in combination as described above do not impair the effects of the present invention, for example, do not exceed the amounts of the compound represented by the formula (1) and dibenzoylmethane, respectively. Range ratios are preferred.

Specific examples of the binder that can be used include, for example, methylcellulose, methoxycellulose, hydroxyethylcellulose, carboxymethylcellulose, sodium carboxymethylcellulose, cellulose, polyvinyl alcohol (PVA), carboxyl group-modified polyvinyl alcohol, sulfonic acid group-modified polyvinyl alcohol, Polyvinyl pyrrolidone, polyacrylamide, polyacrylic acid, starch and derivatives thereof, casein, gelatin, water-soluble isoprene rubber, alkali salt of styrene / maleic anhydride copolymer, iso (or diiso) butylene / maleic anhydride copolymer Water-soluble substances such as alkali salts or polyvinyl acetate, vinyl chloride / vinyl acetate copolymer, polystyrene, polyacrylate, polyurethane, styrene Hydrophobic polymer emulsions such as butadiene (SB) copolymer, carboxylated styrene / butadiene (SB) copolymer, styrene / butadiene / acrylic acid copolymer, and composite particles of colloidal silica and acrylic resin. Can be

Specific examples of the filler that can be used include, for example, calcium carbonate, magnesium carbonate, magnesium oxide, silica, white carbon, talc, clay, alumina, magnesium hydroxide, aluminum hydroxide, aluminum oxide, barium sulfate, and polystyrene resin. Urea-formalin resin.

Other additives that may be used include higher fatty acid metal salts such as zinc stearate and calcium stearate for the purpose of preventing thermal head abrasion and sticking, and phenol derivatives having an antioxidant or antiaging effect. Benzophenone-based, benzotriazole-based ultraviolet absorbers, various surfactants, defoamers and the like can be added as required.

The heat-sensitive recording material of the present invention is prepared using the above-mentioned materials by, for example, the following method. That is, first, a coloring compound, a compound represented by the formula (1),
After dibenzoylmethane is separately pulverized and dispersed in a dispersing machine such as a ball mill, an attritor, a sand mill or the like together with a binder or other additives as necessary (usually water is used when pulverizing and dispersing are performed by a wet method). Is used as a medium) to prepare a thermosensitive coloring layer coating solution, and is usually 1% by dry weight on a support such as paper, plastic sheet or synthetic paper.
It is coated with a bar coater, a blade coater or the like so as to have a weight of about 20 g / m ² and dried to obtain the heat-sensitive recording material of the present invention.

In the heat-sensitive recording material of the present invention, an intermediate layer may be provided between the heat-sensitive coloring layer and the support, or an overcoat layer (protective layer) may be provided on the heat-sensitive coloring layer, if necessary.
The intermediate layer and the overcoat layer (protective layer) are pulverized together with a binder or, if necessary, a heat-fusible compound, a filler, and other additives in the same manner as in the preparation of a thermosensitive coloring layer coating solution.
Disperse and apply to intermediate layer coating solution or overcoat layer (protective layer)
After the coating liquid, the dry weight is usually 0.1 to 10 g / m
It is applied to be about ² .

The heat-sensitive recording material of the present invention containing a colorless or pale-colored compound, the compound represented by the formula (1), and dibenzoylmethane generally has higher sensitivity and less background fog than those conventionally known. Excellent image storability.

[0025]

EXAMPLES The present invention will be described more specifically with reference to examples, but the present invention is not limited to these examples. In the examples, "parts" indicate parts by weight, and "%" indicates% by weight.

Example 1 A mixture having the following composition was pulverized and dispersed using a sand grinder so that the average particle size became 1 μm or less, to prepare a solution [A], a solution [B] and a solution [C], respectively. [A] liquid: 3-dibutylamino-6-methyl-7-anilinofluoran 25 parts 25% PVA aqueous solution 20 parts water 55 parts [B] liquid: a compound represented by the formula (1) (n = 5, melting point) = 129-154 ° C) 25 parts 25% PVA aqueous solution 20 parts Water 55 parts [C] liquid: dibenzoylmethane 25 parts 25% PVA aqueous solution 20 parts Water 55 parts

Next, a thermosensitive coloring layer coating solution was prepared by mixing at the following ratios, coated on a high-quality paper having a basis weight of 50 g / m ² so that the weight when dried was 8 g / m ^2, and dried to obtain a thermosensitive coloring layer. A coloring layer was obtained. [A] solution 8 parts [B] solution 16 parts [C] solution 24 parts 50% aqueous calcium carbonate dispersion 12 parts 50% carboxylated styrene / butadiene copolymer latex 7 parts (formation of protective layer) The protective layer coating solution having the above ratio was applied onto the above-mentioned thermosensitive coloring layer so that the weight when dried was 2 g / m ^2, and dried to obtain a thermosensitive recording material of the present invention having a protective layer. 40% styrene / acrylate copolymer emulsion 20 parts 5% bentonite aqueous dispersion 40 parts 30% zinc stearate aqueous dispersion 3 parts

Example 2 A 25% aqueous solution of 3-dibutylamino-7- (o-chloroanilino) fluoran obtained by pulverizing and dispersing in the same manner as in Example 1 was used instead of the solution [A] in Example 1. In the same manner as in Example 1, a heat-sensitive recording material of the present invention was obtained.

Example 3 A 25% 3- (N-ethyl-N-isopentylamino) -6-methyl-7-anilino obtained by pulverizing and dispersing in the same manner as in Example 1 instead of the solution [A]. A heat-sensitive recording material of the present invention was obtained in the same manner as in Example 1 using an aqueous dispersion of fluoran.

Example 4 A 25% aqueous solution of 3-dipentylamino-6-methyl-7-anilinofluoran obtained by grinding and dispersing in the same manner as in Example 1 was used instead of the solution [A]. In the same manner as in Example 1, a heat-sensitive recording material of the present invention was obtained.

Table 1 shows the quality performance table of the heat-sensitive recording material of the present invention obtained as described above.

Table 1 Quality performance test Background ¹⁾ Color density ²⁾ Water resistance ³⁾ Plasticizer resistance ⁴⁾ Example 1 0.04 1.58 1.42 1.58 Example 2 0.04 1.55 1 .40 1.54 Example 3 0.05 1.60 1.46 1.60 Example 4 0.04 1.59 1.42 1.58

1) Background: A value obtained by measuring the uncolored portion of the sample with a Macbeth reflection densitometer RD-914 (Macbeth reflection density). 2) Color density: Macbeth reflection density value of an image portion printed using a thermal printer (D-805P) manufactured by Ishida Corporation. 3) Water resistance: Macbeth reflection density of an image portion after immersing a sample developed with the above printer in tap water at room temperature for 24 hours. 4) Plasticizer resistance: P is applied to the sample colored with the above printer.
0.0294MPa combined with VC wrap film on both sides
(Macbeth reflection density of an image portion after left for 24 hours at room temperature under a load of (0.3 kg / cm ² )).

As is clear from the table, the heat-sensitive recording material of the present invention is excellent in whiteness of the background and color density, and in the color image, is excellent in water resistance and plasticizer resistance.

[0035]

As described above, a heat-sensitive recording material having high sensitivity, little background fog, and excellent image storability was obtained.

Claims (1)

[Claims] 1. A thermosensitive recording system comprising a support having thereon a heat-sensitive color-forming layer containing, as main components, a colorless compound which is usually colorless or pale, a color-developing compound capable of forming the color-forming compound upon heating, and a sensitizer. In the material, a color-developing compound represented by the following formula (1): (In the formula (1), n = 2 to 10 is represented.) A thermosensitive recording material comprising dibenzoylmethane as a sensitizer.