JPH0361076A - Thermal recording element - Google Patents

Abstract

PURPOSE:To ensure that high-speed recording properties are maintained and the whiteness level of a recording layer does not deteriorate in a storage condition at high temperature by using 3-di-npentylamino-6-methyl-7- phenylaminofluoran and further using a specific compound as a thermally meltable material with the former. CONSTITUTION:A recording layer consisting of a colorless or pale basic dye and a coloring agent which forms a color in contact with the dye is provided on a support. 3-di-n-pentylamino-6-methyl-7phenylaminofluoran is contained as a basic dye and a thermally weltable material expressed by formula I is jointly used. In formula I, x is hydrogen atom, halogen atom, a C1-4 alkyl group or a C1-4 alkoxy group.

Description

[Detailed description of the invention]

"Industrial Application Field" The present invention relates to a heat-sensitive recording medium, which is particularly suitable for high-speed recording,
Moreover, the present invention relates to a heat-sensitive recording material that can stably maintain a recorded image without causing a decrease in whiteness in the blank paper portion. ``Prior Art'' Conventionally, heat-sensitive recording materials utilize a color reaction between a colorless or light-colored basic dye and an organic or inorganic coloring agent to obtain a recorded image by bringing a recoloring substance into contact with heat. well known. Recently, with remarkable progress in thermal recording methods, thermal faxes and the like have become capable of high-speed printing, and it has become possible to record a standard A4 size original in 10 seconds or less. With the speed increase in the hardware field, there is a demand for heat-sensitive recording bodies that are excellent in suitability for high-speed recording. Conventionally, as a means of improving the color development sensitivity of thermal recording materials, a thermofusible substance with a lower melting point than a basic dye or coloring agent is added to the recording layer, and the dye is first absorbed by the melted thermofusible substance. A widely known method is to lower the temperature at which color development starts by dissolving a coloring agent (JP-A-49-34842, JP-A-53-39139, etc.). However, it is generally difficult to make one type of heat-fusible substance have the property of dissolving both a basic dye and a coloring agent, and it is difficult to make a heat-fusible substance with this property. However, the disadvantage is that the temperature at which color development starts falls excessively due to the melting point drop due to the eutectic phenomenon of the dye/coloring agent/thermofusible substance, resulting in a significant decrease in the whiteness of the recording layer. In order to obtain a heat-sensitive recording medium without such drawbacks, JP-A-61-31287 proposes the use of a tephenyl henzyl ether derivative as a thermofusible substance, but such BA 21 Even in thermosensitive recording materials using thermoplastic resin, the whiteness decreases significantly when stored under high-temperature conditions, and further improvements are required. ``Problems to be Solved by the Invention'' In view of the current situation, the present inventors have developed a thermal recording material that has high color development sensitivity and does not lose whiteness even when exposed to high temperature conditions, in addition to thermofusible materials. A wide range of basic dyes used in combination were also examined. As a result, a phenyl-hensylethyl derivative represented by the following +e-10 formula [I] was used as the thermofusible substance, and 3-n-pentylamino-6-methyl-7-
The present inventors have discovered that selective use of phenylaminofluorane achieves this objective, and have completed the present invention. ``Means for Solving the Problems'' The present invention provides a heat-sensitive recording material in which a recording layer containing a colorless or light-colored basic dye and a coloring agent that develops a color upon contact with the dye is provided on a support. , containing 3-di-n-pentylamino-6-methyl-7-phenylaminofluorane as a basic dye, and a thermofusible substance represented by the following general formula CT) is used in combination. This is a heat-sensitive recording medium. [Wherein, X represents a hydrogen atom, a halogen atom, a C0-4 alkyl group, or a C0-4 alkoxyl group. [Function] In the present invention, 3-di-n-pentylamino-6-methyl-7-phenylaminofluoran is used as the basic dye, and as the thermofusible substance, a compound represented by the above general formula [I] is used. Although it is not necessarily clear why a heat-sensitive recording material that not only has excellent high-speed recording properties but also does not cause a decrease in the whiteness of the recording layer even when stored under high-temperature conditions can be obtained when such a base is used in combination with such a base, This is probably because the thermofusible dye and the thermofusible substance exhibit high compatibility, and despite this, the degree of melting point depression due to the eutectic phenomenon is small. Specific examples of the compound represented by the general formula [I] include hensyl-4-methylthiophenyl ether, 4-chlorohensyl-4'-methylthiophenylconitylmethylthiophenyl ether, 3-chlorobenzyl-4
'-Methylthiophenyl ether, 4-methylhensyl-4'-methylthiophenyl ether, 2-methylbenzyl-4'-methylthiophenylco,-ral, 4-butylbenzyl-4'-methylthiophenyl ether, 4
-Methoxyhensyl 4'-methylthiophenyl ether and the like. Of course, the present invention is not limited to these compounds, and two or more kinds of compounds can also be used in combination. In the present invention, 3-di-n-bentylamino-6-methyl-7-phenylaminofluoran is selectively used as the basic dye, but such basic dye and general formula [I] The ratio of the thermofusible substance used is not particularly limited, and usually 1 to 1000 parts by weight, preferably 10 to 300 parts by weight, of the thermofusible substance to 100 parts by weight of the basic dye. It is desirable to adjust within a range of degrees. In the heat-sensitive recording material of the present invention, the coloring agent constituting the recording layer together with the specific basic dye and thermofusible substance is as follows:
It is not particularly limited, but each extract has the property of liquefying, vaporizing, or dissolving when the temperature rises, and also has the property of changing color when it comes into contact with the basic dye.
Examples of the 14 groups that can be used include the following. 4 tcrt-butylphenol, 4-hydroxyphenoxide, α-naphthol, β-nasotol, 4-hydroxyhenduphenone, 4 tert-octylcatechol, 2,2′-dihydroxydiphenyl, 2
2'-methylenehis(4-methyl-6tert-isobutylphenol), 4.4'-isobutyl-2pylidenebis(2-lert-butylphenol), 4.4'-
5ec-butylidenediphenol, 4-phenylphenol, 4,4'-isopropylidenediphenol, 2.
2'-methylenebis(4-chlorophenol), hydroquinone, 44' cyclo\xylidene diphenol, benzyl 4-hydroxybenzoate, dimethyl 4-hydroxyphthalate, hydroquinone monohensyl ether,
4-Hydroxy-4'-isopropoxydiphenylsulfone, 3',4'-tetramethylene 4-hydroxydiphenylsulfone, 44'(1,3-dimethylbutylidene)bisphenol, 4,4'-(1-phenylethylidene) Bisphenol, 4.4'-(p-fu γ-nylene diisopropylene)

[:I pylidene) diphenol, 4.4'-(
Phenolic compounds such as m-phenylene diisopropylidene) diphenol, novolac type phenolic resin, phenol polymer, benzoic acid, p-tert-butylbenzoic acid, trichlorobenzoic acid, terephthalic acid, 3-3e
C-Butyl-4-hydroxybenzoic acid, 3-cyclohexyl-4-hydroxybenzoic acid, Yojo, 3.5-dimethyl-4-hydroxybenzoic acid, salicylic acid, 3-isopropyl→norithylic acid, 3- tert-butylsalicylic acid, 3-hendylsalicylic acid, 3-(α-methylhensyl)salicylic acid, 3-chloro-5-(α-methylhensyl)salicylic acid, 3.5-di-tert-butylsalicylic acid, 3-phenyl-5- Aromatic carboxylic acids such as (α,α-dimethylhensyl)salicylic acid, 3.5-diα-methylhensylsalicylic acid, and these phenolic compounds, aromatic carboxylic acids such as zinc, magnesium, aluminum, calcium, titanium, manganese,
Salts with polyvalent metals such as tin and nickel, and polyvalent metal salts of thiocyanate with zinc, magnesium, aluminum, calcium, titanium, manganese, tin, nickel, etc. and organic compounds such as antipyrine, pyridine, and dimethylaminoantipyrine. Complex compounds with compounds, etc. The proportion of the basic dye and coloring agent used in combination is not necessarily limited, but is usually 100 to 700 parts by weight, preferably 150 to 4 parts by weight, per 100 parts by weight of the basic dye.
00 parts by weight of coloring agent is blended. In addition, two or more types of coloring agents can be used in combination if necessary. Preparation of coating liquids containing these generally uses water as a dispersion medium,
It is prepared by dispersing the dye, the coloring agent, and the thermofusible substance represented by the general formula [I] together or separately using a stirring/pulverizing machine such as a ball bulker, attritor, or sand mill. . Such coating liquids usually contain starches and binders as binders.
Hydroxyethylcellulose, methylcellulose, carboxymethylcellulose, gelatin, casein, gum arabic, polyhinyl alcohol, styrene/maleic anhydride copolymer salt, styrene/acrylic acid copolymer salt, styrene/butadiene copolymer emulsion, etc. in total solid content 10 to 40% by weight, preferably 15 to 30% by weight. Furthermore, various auxiliary agents can be added to the coating liquid.
For example, dioctyl sulfosuccinate I - zolium dodecyl hanzene sulfonate, sodium lauryl alcohol sulfate ester, salt, dispersant of fat 11jj acid metal salt, ultraviolet absorber such as tosol, Other examples include antifoaming agents, fluorescent dyes, and colored dyes. Also,
Dispersions or emulsions of stearic acid, polyethylene, carnauba wax, paraffin wax, zinc stearate, calcium stearate, ester wax, etc. may be added to prevent sticking of the heat-sensitive recording material due to contact with recording equipment or recording heads. can. In addition, inorganic pigments such as kaolin, clay, curk, calcined clay, titanium oxide, diatomaceous earth, fine particulate anhydrous silica, and activated clay are used to improve record and throat scum (=J adhesion). As mentioned above, the heat-sensitive recording material of the present invention has an important feature in that a specific basic dye and a thermofusible substance are used together. As long as the effect of -p-Toluidinofluorane, 3-diethylamino-6-methyl-7phenylaminofluorane, 3-dibutylamino6-methyl-7-phenylaminofluorane, 3-(N-ethyl-
N-isoamyl)amino-6-methyl-7-phenylaminofluorane, 3(N-methyl-N-cyclohexyl)amino-6-methyl-7-phenylaminofluorane, 3diethylamino-7-(o [210 phenyl]
Known basic dyes such as aminofluorane, 3-dibutylamino-7-(chlorophenyl)aminofluorane, stearic acid ξ-do, stearic acid methylene bisamide, oleic acid amide, palmitic acid amide, coconut fatty acid amide, etc. fatty acid amide, 2,2'-methylnonbis(4-methyl6-1ert-butylphenol)
, 1. 1. , 3. , -1 Hindered phenols such as lis(2-methyl-4-hydroxy-5-tertbutylphenyl)butane, 1,2-bis(phenoxy)ethane, 12-bis(4-methylphenoxy)ethane, 1
Various known thermofusible materials such as ethers such as 2-bis(3-methylphenoxy)ethane and 2-naphthylhensyl ether, and esters such as dibenzyl terephcre-1, and ■-hydroxy-2-naphthoic acid phenyl ester. Substances can also be used in combination. As the support, paper, plastic film, synthetic paper, etc. can be used, but paper is most preferably used in terms of cost, coatability, etc. Also, apply the coating liquid that forms the recording layer to the supporting body! li is not limited to 14, but is usually adjusted within a range of about 2 to 12 g/m, preferably about 3 to IO g/% in terms of dry weight. Furthermore, there are no particular limitations on the method of applying the coating liquid.
Any known coating method can be applied as appropriate. The heat-sensitive recording material of the present invention thus obtained has high sensitivity and high whiteness, and remains white even when stored under high temperature conditions, because a specific basic dye and a thermofusible substance are selectively used. In addition, it is difficult for the recording head to get scum attached (
It also exhibits excellent properties in terms of pile-up. Note that it is also possible to provide an overcoat layer on the recording layer for purposes such as protecting the recording layer, and it is of course also possible to provide a protective layer on the back side of the support or an undercoat layer on the support. Furthermore, various known techniques in the field of heat-sensitive recording material production, such as applying adhesive processing to the back surface of the support, can be added. "Example" The present invention will be described in more detail with reference to Examples below, but the present invention is of course not limited to these. In addition, unless otherwise specified, parts and percentages in the examples refer to parts by weight and percentages by weight, respectively. Examples] [Formation of undercoat layer] Calcined clay (trade name: Ancilesox, apparent specific gravity:
0.22g/cnf, manufactured by Engelhard) 100 parts Styrene-butadiene copolymer Latte Nox (solid content:
50%) 15 parts polyvinyl alcohol 10% water? 9t (! 30 parts water
A primer coating solution was prepared by mixing 200 parts of the above composition. 5 of the obtained coating liquid
Is the coating amount after drying 10 g/n on 0 g/m high-quality paper? An undercoat layer was formed by coating and drying. [Preparation of thermal recording paper] ■ A wave preparation 3-di-n-pentylamino-6-methyltophenylaminofluorane 10 parts Hensyl-4-methylthiophenyl ether 20 parts 4 Methyl cellulose 5% aqueous solution 15 parts water
120 parts of this composition was ground in a sand mill until the average particle size was 3 μm. ■ Preparation of Solution B 4. 4'-isopropylidenediphenol 30 parts Methyl cellulose 5% aqueous solution 30 parts water
70 parts of this composition was pulverized using a Zandosil until the average particle size was 3 μm. ■ Formation of recording layer 165 parts of liquid A, 130 parts of liquid B, silicon oxide pigment (oil absorption 1
80ml/100g), 150 parts of a 20% oxidized starch aqueous solution, and 55 parts of water were mixed and stirred to prepare a coating liquid. The resulting coating liquid was applied onto the undercoat layer at a dry weight of 5.0 g/
A heat-sensitive recording paper was obtained by coating and drying so as to obtain RL. Example 2 B of Example 1? In the ffL preparation, 4-hydroxy-
A thermosensitive recording paper was obtained in the same manner as in Example 1 except that 4'-isopropoxydiphenyl sulfone was used. Examples 3 to 5 In the preparation of Solution A of Example 1, 4-chlorobenzyl-4 was used instead of benzyl-4 methylthiophenyl ether.
'-Methylthiophenyl ether (Example 3), 4-methylhensyl-4'-methylthiophenyl ether (Example 4), and 3-chlorohensyl-4'-methylthiophenyl ether (Example 5) were used. Three types of thermal recording paper were obtained in the same manner as in Example 1. Comparative Example 1 In the preparation of Solution A of Example 1, 3-(N-methyl-Ncyclohexyl)adan-6=methyl was used instead of 3-di-n-pentylated 6-methyl-7-phenylated fluorane. A thermosensitive recording paper was obtained in the same manner as in Example 1 except that -7-phenylagonofluorane was used. The six types of thermal recording paper thus obtained were placed in a Kyocera simulator (voltage: 15V, pulse cycle: 5m 5e).
c), record the pulses at 1110.30 m sec and 0, 45 m sec, and measure the color density using a Maches densitometer (model RD-100R, using an amber filter).
The results are shown in Table 1. In addition, the whiteness of the recording layer before recording was measured using a Hunter whiteness meter, and the thermal recording paper was placed in an atmosphere of 60°C for 2 hours.
After standing for 4 hours, the whiteness was measured again in the same manner, and the results are shown in Table 1. Table 1 "Effects" As is clear from the results in Table 1, the heat-sensitive recording material of the present invention has high sensitivity and high whiteness, and has the advantage of not causing a decrease in whiteness even when exposed to high temperature conditions. It was a recording body.

Claims (1)

[Scope of Claims] A thermosensitive recording material comprising a support and a recording layer containing a colorless or light-colored basic dye and a coloring agent that develops color upon contact with the dye, wherein 3- 1. A heat-sensitive recording material containing di-n-pentylamino-6-methyl-7-phenylaminofluorane and in combination with a thermofusible substance represented by the following general formula [I]. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [I] [In the formula, X represents a hydrogen atom, a halogen atom, an alkyl group of C_1 to_4, or an alkoxyl group of C_1_ to_4. ]