JPH07257031A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance storage stability such as light fastness or heat resistance by adding a salicylic acid anilide derivative represented by a predetermined formula to a thermal recording layer. CONSTITUTION:At least one kind of a salicylic acid anilide derivative represented by formula (wherein R1 and R2 are a hydrogen atom, an alkyl group or a halogen atom, R3 is a hydrogen atom or an alkyl group, X1 and X2 are a hydrogen atom, a hydroxyl group or an alkyl group and at least one of X1 and X2 is a hydroxyl group or an alkyl group, X3-X5 are a hydrogen atom, a hydroxyl group, a halogen atom or an alkyl group and at least one of X1-X5 is a hydroxyl group) is added to a thermal recording layer. This salicylic acid anilide derivative can be produced by reacting phenyl salicylate and an aminophenol compd. and the use amt. thereof is determined on the basis of required capacity, recording aptitude and the kind and use amt. of a dye or the kind and use amt. of an additive.

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 having improved storage stability, and more specifically, by containing a specific anilide salicylate derivative in the heat-sensitive recording layer,
The present invention relates to a heat-sensitive recording material having improved storage stability such as light resistance and heat resistance.

[0002]

2. Description of the Related Art A heat-sensitive recording material generally comprises a colorless or light-colored color-forming substance and a color-developing agent which develops the color-forming substance when subjected to heat, a sensitizer and a binder. It is produced by coating the surface of a support such as paper, synthetic paper, plastic film or sheet together with other additives. And
In a recording device, when a heating element such as a thermal head or a heating pen comes into contact, the color-forming substance reacts with a developer to develop a black color or the like for recording. Such a recording medium (thermosensitive recording material) does not require complicated processing such as development and fixing as compared with other recording mediums, and recording can be obtained with a relatively simple device in a short time, Not only recording materials for copying books, documents, etc., but also various measuring recording papers, computers, facsimiles, telex, boarding because of the advantages of low generation, low environmental pollution, low cost, etc. It is widely used as a recording material for vending machines such as tickets, prepaid cards, and labels.

In conventional heat-sensitive recording materials, a color-developing substance (leuco dye), a color-developing agent for thermally developing the color-developing substance, and a sensitizer, which is used as necessary, are used in an appropriate combination to obtain color-developing sensitivity. Also, from the viewpoint of background fog, what is practically satisfactory is obtained.

However, when these thermosensitive recording materials are exposed to sunlight or lighting such as fluorescent lamps for a long period of time,
Not only the printing part (coloring part) is faint or disappears, but also the background part is discolored (yellowing), and the printed out items such as facsimile receiving paper, word processor and PC are left on the desk. In this case, the recorded image becomes unclear, which is a problem in terms of document storage.

Further, the conventional heat-sensitive recording materials are not only inferior in light resistance, but also have drawbacks such as fingerprints or plasticizers transferred from desk mats such as vinyl chloride resin, which also lower storage stability and heat resistance. Therefore, there is a strong demand for improving the storage stability of heat-sensitive recording materials.

For this reason, JP-A-53-11036, JP-A-58-49294 and JP-A-59-14.
Japanese Patent Laid-Open No. 0096, for example, proposes that the addition of a salicylic acid amide compound improves the color development sensitivity, the stability of the color image with respect to the plasticizer, and the stability of the background portion. However, when these compounds are used, the storage stability such as light resistance and heat resistance is still insufficient, and they are not completely satisfactory in practical use.

Therefore, it is an object of the present invention to provide a heat-sensitive recording material having improved storage stability such as light resistance and heat resistance.

[0008]

As a result of intensive studies, the present inventors have found that a heat-sensitive recording material containing a specific anilide salicylate derivative in the heat-sensitive recording layer can achieve the above object. I found out that.

The present invention has been made based on the above findings, and at least a salicylic acid anilide derivative represented by the following general formula (I) represented by the following [Chemical formula 2] (the same as the above-mentioned [Chemical formula 1]) is contained in the thermosensitive recording layer. The present invention provides a thermosensitive recording material containing one kind.

[0010]

[Chemical 2]

The thermal recording material of the present invention will be described in detail below.

The salicylic acid anilide derivative used in the present invention is a component used for improving the storage stability in the heat-sensitive recording material of the present invention, and has a color developing property by itself, and is a color developing agent. It is a component that also has the function of.

In the salicylic acid anilide derivative used in the present invention, R _{1 to} R ₃ and X _{1 to} X ₅ of the above general formula (I) are used.
Examples of the alkyl group represented by include methyl, ethyl, propyl, butyl, sec-butyl, tert-butyl, pentyl, hexyl, octyl, tert-octyl, 2-ethylhexyl, nonyl, isononyl, decyl, dodecyl and the like groups. To be

Further, R ₁ , R ₂ and X _{3 of} the above general formula (I) are
As the halogen atom represented by ~ X ₅ , fluorine, chlorine,
Examples include atoms such as bromine and iodine.

Therefore, as typical representative examples of the salicylic acid anilide derivative represented by the above general formula (I), compounds No. 1 to No. 10 shown in the following [Chemical formula 3] to [Chemical formula 12] are listed. To be

[0016]

[Chemical 3]

[0017]

[Chemical 4]

[0018]

[Chemical 5]

[0019]

[Chemical 6]

[0020]

[Chemical 7]

[0021]

[Chemical 8]

[0022]

[Chemical 9]

[0023]

[Chemical 10]

[0024]

[Chemical 11]

[0025]

[Chemical 12]

The salicylic acid anilide derivative represented by the general formula (I) can be easily produced, for example, by reacting phenyl salicylate with an aminophenol compound, but the production method is not particularly limited.

[Synthesis Examples] Specific synthesis examples of the salicylic acid anilide derivative represented by the above general formula (I) used in the present invention are shown below. However, the present invention is not limited to these synthetic examples.

Synthesis Example 1 Synthesis of Compound No. 1 (shown in [Chemical Formula 3] above)

Phenyl salicylate 11.8 g (0.05
5 mol) and 5.5 g of o-aminophenol (0.0
5 mol) is dissolved in 50 g of dimethylformamide and the temperature is raised. After reacting at 160 ° C. for 5 hours, the reaction solution was poured into water to cause crystallization, which was separated by filtration. The crude product was recrystallized from a mixed solvent of toluene / ethanol to give an infrared absorption spectrum of 1610.
9.7 g (yield 85%) of the desired product having a melting point of 169.4 ° C. and having an anilide absorption at cm ⁻¹ was obtained.

Synthesis Example 2 Synthesis of Compound No. 6 (shown in [Chemical Formula 8] above)

Phenyl salicylate 11.2 g (0.05
2 mol) and 6.2 g of 4-amino-m-cresol
(0.05 mol) and 2 g of a mixture of 25 g of diglyme.
The reaction was carried out at 00 ° C for 7 hours. After the solvent was removed, the residue was poured into toluene for crystallization, and the crystal was washed with hot toluene to have 10.6 g of the desired product having an anilide absorption at 1595 cm ⁻¹ in an infrared absorption spectrum and a melting point of 189 ° C. (yield 87. 5%) was obtained.

The amount of the above anilide salicylate derivative used in the present invention depends on the required performance and recording suitability,
The dye (color-forming substance) to be described later or other additives such as other developers and sensitizers to be used in combination varies depending on the kind and the amount used, and is not particularly limited, but usually 1 part by weight of the color-forming substance is used. 0.01 to 10 parts by weight, preferably 0.1 to 5 parts by weight. When the amount used is less than 0.01 parts by weight with respect to 1 part by weight of the color-forming substance, the effect of improving storage stability is poor, and even when it is used in excess of 10 parts by weight, the effect is not improved. It is uneconomical as it does not grow any further.

The heat-sensitive recording material of the present invention comprises a heat-sensitive recording layer and a support, and the heat-sensitive recording layer contains the anilide salicylate derivative. Further, the heat-sensitive recording layer is formed by the anilide salicylate derivative and a color-forming substance, and further, if necessary, a developer, various sensitizers, known storage stabilizers, and the like are formed. You can

The above-mentioned color-forming substance is usually a colorless or light-colored color-forming substance, and various dyes are used as the color-forming substance, provided that they are used in general heat-sensitive recording materials. No particular restrictions.

Specific examples of the dye (color-forming substance) include (1) 3,3-bis (p-dimethylaminophenyl) -6-dimethylaminophthalide and 3- (p-
Dimethylaminophenyl) -3- (2-phenyl-3-
Indolyl) phthalide, 3- (p-dimethylaminophenyl) -3- (1,2-dimethyl-3-indolyl) phthalide, 3,3-bis (9-ethyl-3-carbazolyl) -5-dimethylaminophthalide , 3,3-bis (2
-Phenyl-3-indolyl) -5-dimethylaminophthalide and other triarylmethane compounds; (2) 4,
4-bis (dimethylamino) benzhydrin benzyl ether, diphenylmethane compounds such as N-2,4,5-trichlorophenylleukoauramine; (3) rhodamine-β-anilinolactam, 3- (N-methyl-) N
-Cyclohexylamino) -6-methyl-7-anilinofluorane, 3-diethylamino-7-octylaminofluorane, 3-diethylamino-7- (2-chloroanilino) fluorane, 3-diethylamino-6-methyl-7- Anilinofluorane, 3-diethylamino-6-
Methyl-7- (2,4-dimethylanilino) fluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-diethylamino-6-chloro-7- (β-ethoxyethylamino) fluorane, 3-diethylamino- 6-chloro-7- (γ-chloropropylamino) fluorane, 3- (N-ethyl-N-isoamylamino)-
6-methyl-7-anilinofluorane, 3- (N-ethyl-N-ethoxyethylamino) -6-methyl-7-anilinofluorane, 3- (N-ethyl-N-tetrahydrofurfurylamino) -6-Methyl-7-anilinofluorane, 3- (N-ethyl-N-tolylamino) -6-
Methyl-7-anilinofluorane, 3-N, N-dibutylamino-6-methyl-7-anilinofluorane, 3-
Dibutylamino-7- (2-chloroanilino) fluorane, 3-dipentylamino-6-methyl-7-anilinofluorane, 3-piperidino-6-methyl-7-anilinofluorane, 3- (4-anilino) Xanthene-based compounds such as anilino-6-methyl-7-chlorofluorane; (4) Thiazine-based compounds such as benzoylleucomethylene blue and p-nitrobenzoylleucomethylene blue; (5) 3-Methylspirodinaphthopyran, 3-ethyl Spirodinaphthopyran, 3-benzyl spirodinaphthopyran, 3-methylnaphtho- (3-methoxybenzo)
Spiro compounds such as spiropyran; (6) Others 3,
5 ', 6-tris (dimethylamino) -spiro [9H-
Fluorene-9,1 '(3'H) -isobenzofuran]
-3'-one, 1,1-bis [2- (4-dimethylaminophenyl) -2- (4-methoxyphenyl) ethenyl] -4,5,6,7-tetrachloro (3H) isobenzofuran-3 -On, etc., and these dyes may be used alone or in combination of two or more.

Further, as described above, the anilide salicylate derivative used in the present invention exerts the effect as a developer by itself, so that it is not necessary to use another developer, but the coloring sensitivity is further improved. When it is necessary to increase the amount, other known color developers such as phenol type, organic carboxylic acid type and metal salt type can be used in combination. Further, the amount of the above-mentioned anilide salicylate derivative used can be reduced by using these other color developers in combination.

Examples of the other developers include p-octylphenol, p-tertiary butylphenol, p-phenylphenol, p-hydroxyacetophenone and α.
-Naphthol, β-naphthol, p-tertiary octylcatechol, 2,2'-dihydroxybiphenyl, bisphenol-A, 1,1-bis (p-hydroxyphenyl)
Butane, 2,2-bis (4-hydroxyphenyl) heptane, 2,2-bis- (3-methyl-4-hydroxyphenyl) propane, 2,2-bis (3,5-dimethyl-)
4-hydroxyphenyl) propane, 2,2-bis (3,5-dichloro-4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) sulfone, bis (3-allyl-4-hydroxyphenyl) sulfone, bis ( 3,4-dihydroxyphenyl) sulfone, 1,1
-Bis (4-hydroxyphenyl) cyclohexane, bis (4-hydroxyphenyl) ether, bis [2-
(4-Hydroxyphenylthio) ethoxy] methane, 4
-(4-Isopropoxybenzenesulfonyl) phenol, dimethyl 4-hydroxyphthalate, butyl bis (4-hydroxyphenyl) acetate, benzyl p-hydroxybenzoate, phenolic such as 3,5-di-tert-butylsalicylic acid, benzoin Examples include organic carboxylic acid-based developers such as acids and metal salt-based developers such as zinc salicylate. Of these, phenol-based developers are particularly preferably used.

The amount of the other color developer used is usually 0.1 to 10 parts by weight, preferably 0.2 to 5 parts by weight, based on 1 part by weight of the color forming substance. When the amount used is less than 0.1 parts by weight with respect to 1 part by weight of the color-forming substance, the coloring sensitivity is insufficient, and even if it is used in excess of 10 parts by weight, the effect is It is uneconomical without increasing.

The above-mentioned sensitizer is used for increasing the color developing sensitivity of the heat-sensitive recording material of the present invention. Examples of the sensitizer include zinc acetate, zinc octylate, zinc laurate and stearic acid. Metal salts of organic acids such as zinc, zinc oleate, zinc behenate, zinc benzoate, zinc salicylate dodecyl ester, calcium stearate, magnesium stearate, aluminum stearate; stearic acid amide, methylol stearate, stearoyl urea, Amide compounds such as acetanilide, acetotoluidide, acetoacetic acid anilide, benzoic acid stearylamide, ethylenebisstearic acid amide, hexamethylenebisoctylic acid amide; 1,2-bis (3,4-dimethylphenyl) ethane, m-terphenyl, 1,2-jifu Nokishietan, 1,2-bis (3
-Methylphenoxy) ethane, p-benzylbiphenyl, p-benzyloxybiphenyl, diphenyl carbonate, bis (4-methylphenyl) carbonate, dibenzyl oxalate, bis (4-methylbenzyl) oxalate, 1-hydroxy-2- Phenyl naphthalenecarboxylate, benzyl 1-hydroxy-2-naphthalenecarboxylate, phenyl 3-hydroxy-2-naphthalenecarboxylate, methylenedibenzoate, 1,4-bis (2
-Vinyloxyethoxy) benzene, 2-benzyloxynaphthalene, benzyl 4-benzyloxybenzoate, dimethyl phthalate, dibenzyl terephthalate, dibenzoylmethane, 4-methylphenoxy-p-biphenyl, and the like. The agent is usually used in an amount of 0.1 to 10 parts by weight with respect to 1 part by weight of the color forming substance.

When the heat-sensitive recording material of the present invention is required to have a high degree of water resistance, heat resistance and oil resistance, the object of the present invention can be achieved by using it together with other storage stabilizers. it can.

Examples of the above other storage stabilizers include 1,
1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,1,3-tris (2-
Methyl-4-hydroxy-5-cyclohexylphenyl) butane, 4,4′-butylidene bis (2-tert-butyl-5-methylphenol), 4,4′-thiobis (2
-Tert-butyl-5-methylphenol), 2,2'-thiobis (6-tert-butyl-4-methylphenol),
Hindered phenol compounds such as 2,2′-methylenebis (6-tert-butyl-4-methylphenol), 4-
Benzyloxy-4 ′-(2-methylglycidyloxy) diphenyl sulfone, sodium-2,2′-methylenebis (4,6-di-tert-butylphenyl) phosphate, etc. may be mentioned, and these storage stabilizers are usually 0.1 to 10 parts by weight is used for 1 part by weight of the color forming substance.

The heat-sensitive recording material of the present invention can be obtained, for example, as follows. The salicylic acid anilide derivative used in the present invention, a color-forming substance (color-forming colorless dye),
Other developers, sensitizers, and other storage stabilizers used as necessary are usually atomized by a grinding machine such as a ball mill, an attritor, or a sand grinder or a suitable emulsifying device, and depending on the purpose. Further, various kinds of additive materials are added to prepare a coating liquid, and the coating liquid is applied to a material used as a support of a usual thermal recording material such as paper or various films to obtain the objective thermal recording of the present invention. The material can be obtained.

The above-mentioned coating liquid is usually polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose,
Polyvinylpyrrolidone, polyacrylamide polymer, starches, styrene-maleic anhydride copolymer, vinyl acetate-maleic anhydride copolymer, styrene-butadiene copolymer or a binder such as a modified product thereof, kaolin,
Fillers such as silica, diatomaceous earth, talc, titanium dioxide, calcium carbonate, magnesium carbonate, aluminum hydroxide, and melamine are mixed, but in addition to this, metallic soaps,
Amides, waxes, light stabilizers, water-proofing agents, dispersants, defoamers and the like can be blended and used as necessary.

The heat-sensitive recording material of the present invention can be used in various applications such as facsimile paper, printer paper, label, price tag, ticket, etc. to which the heat-sensitive recording material is applied.

[0045]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples. However, the present invention is not limited to these examples.

Example 1 20 g of 3- (N, N-dibutylamino) -6-methyl-7-anilinofluorane and 100 g of a 10% aqueous polyvinyl alcohol solution were thoroughly ground to prepare a dispersion A.

20 g of sample compound (shown in Table 1 below)
Was ground in a ball mill together with 100 g of a 10% aqueous solution of polyvinyl alcohol to obtain a dispersion B.

20 g of 2-benzyloxynaphthalene and 100 g of a 10% aqueous polyvinyl alcohol solution were sufficiently ground to obtain a dispersion C.

Dispersion D was obtained by grinding 20 g of zinc stearate in a ball mill together with 100 g of a 10% aqueous solution of polyvinyl alcohol.

Dispersion E was obtained by grinding 20 g of polyethylene wax in a ball mill together with 100 g of 10% aqueous polyvinyl alcohol solution.

The above dispersions A, B, C, D and E were mixed with 1:
Mix at a weight ratio of 2: 2: 0.3: 0.3 to form a mixture 20
50 g of calcium carbonate was added to 0 g of the solution to disperse it sufficiently to obtain a coating solution. This coating solution was coated on a base paper of 50 g / m ² to a thickness of 32 μm and dried to obtain a heat-sensitive recording material.

Using the obtained heat-sensitive recording material, a heat-sensitive printing device (TH-PMD: manufactured by Okura Electric Co., Ltd.) was used to print a recorded image with a pulse width of 0.8 msec. ) Was measured with a Macbeth densitometer (Model RD-933 manufactured by Macbeth Co.).

Further, in order to evaluate the light fastness, the color-developed heat-sensitive recording material was placed in a carbon arc fade meter, and the densities of the printed portion and the background portion were measured after irradiation for 10 hours. In addition, the density of the background portion was measured using a yellow filter.

The results are shown in Table 1 below.

[0055]

[Table 1]

[0056]

[Chemical 13]

[0057]

[Chemical 14]

Example 2 20 g of 3- (N-ethyl-N-isoamylamino) -6-methyl-7-anilinofluorane and 100% aqueous solution of polyvinyl alcohol 100
g was thoroughly ground to obtain a dispersion A.

20 g of bisphenol A and 100 g of a 10% aqueous solution of polyvinyl alcohol were thoroughly ground to obtain a dispersion B.

4-benzylbiphenyl 20 g and 10
% Polyvinyl alcohol aqueous solution 100 g was sufficiently ground to obtain Dispersion C.

20 g of sample compound (shown in [Table 2] below)
Was ground in a ball mill together with 100 g of a 10% aqueous polyvinyl alcohol solution to obtain a dispersion D.

Dispersions A, B, C and D and fine powdery silica were mixed in a weight ratio of 1: 3: 2: 1: 0.5 and sufficiently dispersed to obtain a coating liquid. A heat-sensitive recording material was obtained by coating on a base paper of 50 g / m ^{2 in} a thickness of 32 μm and drying.

Using the heat-sensitive recording material thus obtained, a heat-sensitive printing device (TH-PMD: made by Okura Electric Co., Ltd.) was used to print a recorded image with a pulse width of 0.8 msec. The initial concentration) was measured by a Macbeth densitometer (Model RD-933 manufactured by Macbeth Co.).

Further, this color-developed thermosensitive recording material
It was stored under conditions of dryness (° C.) for 24 hours and under conditions of 40 ° C. and relative humidity of 90% (wet heat) for 24 hours, and the density of the printed part was measured to evaluate heat resistance.

The results are shown in [Table 2] below.

[0066]

[Table 2]

From the results of the above [Table 1] and [Table 2], the following is clear. A heat-sensitive recording material in which a salicylic acid anilide derivative (Comparative Compounds 1 and 2) other than the salicylic acid anilide derivative represented by the general formula (I) is added to the heat-sensitive recording layer (Comparative Examples 1-1, 1-2, 2-1). And 2-2) is
The initial color density and background stain are excellent, but the storage stability such as light resistance and heat resistance (storage under dry heat, storage under wet heat) is not sufficient. In contrast, the salicylic acid anilide derivative represented by the general formula (I) (compound N
The heat-sensitive recording materials (Examples 1-1 to 1-10 and 2-1 to 2-4) in which (1) to (No. 10) are added to the heat-sensitive recording layer have light resistance and heat resistance (preservation when dried). , Storage under wet heat) and so on. In particular, even after being irradiated with ultraviolet rays, not only the effect of preventing the discoloration of the colored portion and the discoloration of the background portion is extremely great, but also the background fog is small. Moreover, the salicylic acid anilide derivative represented by the general formula (I) gives an excellent color-developed image without using any other developer, and has an effect as a developer having excellent storage stability. It plays.

[0068]

The heat-sensitive recording material of the present invention having a specific anilide salicylate derivative contained in the heat-sensitive recording layer has improved storage stability such as light resistance and heat resistance. The heat-sensitive recording material of the present invention is particularly one in which discoloration of the color-developed portion and the background portion is prevented even when it is exposed to sunlight, a fluorescent lamp or the like for a long period of time.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Atsuro Tomita 5-2-13 Shirahata, Urawa City, Saitama Prefecture Asahi Denka Kogyo Co., Ltd.

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a heat-sensitive recording layer containing at least one salicylic acid anilide derivative represented by the following general formula (I). [Chemical 1]