JPH0374636B2 - - Google Patents

Description

[Detailed description of the invention]

<Industrial Application Field> The present invention relates to a heat-sensitive recording material, and more specifically, to improving the image stability of a heat-sensitive recording material having a heat-sensitive coloring layer containing a leuco dye and a color developer that reacts with the dye to form a color. Regarding improvements. <Prior Art> In general, a heat-sensitive recording material having a heat-sensitive coloring layer mainly composed of a colorless or light-colored leuco dye and a color developer that reacts with the leuco dye to form a color is different from other heat-sensitive recording materials that have been put to practical use in the past. Because the color image obtained is very clear compared to the material, it is widely used as recording paper for computer output, facsimiles, recorders, etc., and also for tickets, cards, etc. However, when a recording sheet using this heat-sensitive recording material comes into contact with water, plasticizer, oil, etc. for a long period of time, the coloring part fades, and improvements are needed. In order to improve these drawbacks, dimethyl terephthalate (Japanese Patent Application Laid-open No. 57-129785), benzophenone derivatives having SO ₃ groups (Japanese Patent Application Laid-open No. 57-199686),
Metal salts of benzoin compounds
132589), sulfone compounds (JP-A-58-205793),
Amide compound (JP-A-58-211495), 1, 1, 3
-Tris-(3-t-butyl-4-hydroxy-
6-Methylphenyl)-butane (JP-A-1986-
2884), anilide compounds (Japanese Patent Publication No. 59-9092), zinc dithiocarbamate compounds (Japanese Patent Application Publication No. 59-41296)
However, sufficient image stability, especially water resistance, plasticizer resistance, and oil resistance effects have not yet been obtained. <Problems to be Solved by the Invention> In view of the above problems, the present invention provides an image of a heat-sensitive recording material having a heat-sensitive coloring layer containing a leuco dye and a color developer that reacts with the leuco dye to form a color. Aimed at improving stability and thermal sensitivity. <Means for Solving the Problems> In a heat-sensitive recording material in which a heat-sensitive color-forming layer is provided on a support, the heat-sensitive color forming layer is mainly composed of a leuco dye and a color developer that reacts with the leuco dye to form a color. (In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ are alkyl groups, allyl groups, aralkyl groups, alicyclic groups, hydroxyl groups,
By containing at least one compound represented by an alkyl group having a hydroxyl group, a phenyl group, or a phenyl group having a substituent in the heat-sensitive coloring layer, remarkable image stability, especially water resistance, plasticizer resistance, oil resistance, Furthermore, they have newly discovered that thermal sensitivity can be improved, and have completed the present invention. It is not clear why the image stability against water, plasticizers, oil, etc. is improved by coexisting the compound represented by the above general formula in the thermosensitive coloring layer, but the combination of the leuco dye and color developer is not clear. This is thought to be because the above-mentioned compound participates in the coloring system formed by the reaction and reduces the solubility of the coloring compound in water, plasticizer, oil, etc. The above compound in the present invention Specific examples are shown in Table 1.

【table】 Examples are shown in Table 2.

【table】

Examples are shown in Table 3.

[Table] The compounds exemplified above can be used in the present invention, but are not limited thereto. Examples of typical leuco dyes used in the present invention include crystal violet lactone, 3-indolino-3-p-dimethylaminophenyl-6-
Dimethylaminophthalide, 3-diethylamino-
7-chlorofluorane, 3-diethylamino-5
-Methyl-7-t-butylfluorane, 3-diethylamino-6-methyl-7-anilinofluorane, 3-diethylamino-6-methyl-7-p-
Butylanilinofluorane, 3-diethylamino-7-dibenzylaminofluorane, 3-cyclohexylamino-6-chlorofluorane, 3-diethylamino-6-methyl-7-xylidinofluorane, 2-anilino-3- Methyl-6-(N-
ethyl-p-toluidino)fluorane, 3-pyrrolidino-6-methyl-7-anilinofluorane,
3-pyrrolidino-7-cyclohexylaminofluorane, 3-piperidino-6-methyl-7-toluidinofluorane, 3-pyrrolidino-6-methyl-7-(p-toluidino)fluorane, 3-piperidino-6- Methyl-7-anilinofluorane,
3-N-methylcyclohexylamino-6-methyl-7-anilinofluorane, 3-diethylamino-7-(m-trifluoromethylanilino)fluorane, 1,3-(N-ethyl-N-isoamylamino) Examples include, but are not limited to, -6-methyl-7-anilinofluorane. In addition, as a color developer that develops color by reacting with the above leuco dye, for example, 4-phenylphenol, 4-hydroxyacetophenone, 2,2'-dihydroxydiphenyl,
2,2'-methylenebis(4-chlorophenol),
2,2'-methylenebis(4-methyl-6-t-butylphenol), 4,4'-isopropylidenebis(2-methylphenol), 4,4'-ethylenebis(2-methylphenol), 1, 1′-bis(4′-hydroxyphenyl)-cyclohexane,
2,2'-bis(4-hydroxyphenyl)propane, 4,4'-cyclohexylidenebis(2-isopropylphenol), novolac type phenolic resin, 3-5-di-t-butylsalicylic acid, 3-
Examples include 5-di-α-methylbenzylsalicylic acid, 3-methyl-5-t-butylsalicylic acid, phthalic acid monoanilide paraethoxybenzoic acid, bis(4-hydroxyphenyl)acetate, 4-hydroxybenzoic acid ester, etc. However, it is not limited to these. Furthermore, inorganic and organic pigments such as aluminum hydroxide, heavy and light calcium carbonate, titanium oxide, barium sulfate, silica gel,
Activated clay, talc, clay, satin white, kaolinite, calcined kaolinite, diatomaceous earth, synthetic kaolinite, polyolefin particles, polystyrene particles, urea-formalin resin particles, etc., and sensitizers such as stearamide, palmitin, etc. acid amide, oleic acid amide, lauric acid amide,
Ethylene bis stearamide, methylene bis stearamide, methylol stearamide,
Paraffin wax, higher alcohol, higher resin acid, etc. may be added. The above-mentioned heat-sensitive components of the present invention can be used as a support, for example,
As a binder for forming a heat-sensitive layer on paper, synthetic paper, resin film, or composites thereof, etc.
Water-soluble or water-insoluble resin binders can be used, but water-soluble resins are preferably used, such as casein, gelatin, polyvinyl alcohol,
Modified polyvinyl alcohol, polyvinylpyrrolidone, starch, modified starch, isobutylene-maleic anhydride resin, diisobutylene-maleic anhydride resin, styrene-maleic anhydride resin, polyacrylamide, modified polyacrylamide, carboxyl methyl cellulose, methyl vinyl ether-maleic Acid copolymers, methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose, as well as water-soluble emulsions,
Vinyl acetate, polystyrene, acrylic ester, vinyl chloride-vinyl acetate copolymer, etc. are used alone or in combination. Furthermore, if necessary, a curing agent is added to harden these binders and make them water resistant.
Chemical resistance may also be improved. Further, a coating layer may be provided on the heat-sensitive coloring layer containing the compound of the present invention,
An under layer may also be provided between the coloring layer and the support. <Examples> The present invention will be explained in detail below using Examples. below,
Parts represent parts by weight. Solutions A to G were prepared by pulverizing and dispersing mixtures having the following formulations in a ball mill for one day. Solution A 3-(N-ethyl-isobutylamino)-6-
Methyl-7-anilinofluorane 25 parts 5% hydroxyethylcellulose aqueous solution 50 parts Water 25 parts Solution B Methyl bis(4-hydroxyphenyl)acetate
25 parts 5% hydroxyethyl cellulose aqueous solution 50 parts Water 25 parts Solution C Light calcium carbonate 40 parts 10% polyvinyl alcohol aqueous solution 40 parts Water 20 parts Solution D Tetrahydro-3,5-dimethyl-2H-1,
3,5-thiadiazine-2-cation (Table 1
No. 1 compound, m, p: 105℃) 25 parts 10% polyvinyl alcohol aqueous solution 25 parts Water 50 parts Solution E 3,3'-ethylenebis(tetrahydro-5-
Methyl-2H-1,3,5-thiadiazine-2
-thione) (compound No. 28 in Table 2, m,
p: 191℃) 25 parts 10% polyvinyl alcohol aqueous solution 25 parts Water 50 parts Liquid F Tetrahydro-3-methyl-5-benzyl-
2H-1,3,5-thiadiazine-2-thione (compound No. 2 in Table 1, m, p: 92°C)
25 parts 10% polyvinyl alcohol aqueous solution 25 parts Water 50 parts Solution G 1,1,3-tris(3-t-butyl-4-
Hydroxy-6-methylphenyl)-butane
25 parts 10% polyvinyl alcohol aqueous solution 25 parts Water 50 parts Example 1 10 parts of the above liquid A, 25 parts of liquid B, 25 parts of liquid C, 15 parts of liquid D
1 part and 25 parts of a 10% polyvinyl alcohol aqueous solution were mixed to obtain a heat-sensitive recording paint. The paint was applied to high-quality paper so that the coating weight after drying was 6 g/m ² and dried to form a heat-sensitive layer. Example 2 A thermosensitive recording paper was produced in exactly the same manner as in Example 1 except that Liquid D was replaced with Liquid E. Example 3 A thermosensitive recording paper was produced in exactly the same manner as in Example 1 except that Liquid D was replaced with Liquid F. Comparative Example 1 A thermosensitive recording paper was produced in exactly the same manner as in Example 1 except that Liquid D was replaced with Liquid G. Comparative Example 2 A thermosensitive recording paper was produced in exactly the same manner as in Example 1 except that Liquid D was replaced with Liquid B. When the thermal recording papers obtained in Examples 1, 2, and 3 and Comparative Examples 1 and 2 were colored on a 90°C hot plate, the optical results shown in Table 4 were obtained using a Macbeth reflection densitometer RD-514 model. Image obtained. As shown in Table 4, the thermal recording paper obtained in the comparative example had a low color density and
Since sufficient color development could not be obtained, the recording paper of this comparative example was colored on a hot plate at 120° C. and tested for heat resistance, plasticizer resistance, and oil resistance, and measurements were made using the densitometer described above. Heat resistance: The thermosensitive recording paper was submerged in a water tank, and the density of the colored area was measured 12 hours later. Plasticizer resistance: A plastic eraser (PE-01 manufactured by Tombow Pencil Co., Ltd.) was brought into contact with the colored area under pressure, and the density of the colored area was measured after 1 hour. Oil resistance: Several drops of edible soybean oil were dropped on the colored area, and after 1 hour, the oil was wiped off with gauze, and the density of the colored area was measured. The results of these tests are shown in Table 4.

[Table] <Effects of the Invention> As shown in Table 4, the compound of the present invention is contained in a heat-sensitive coloring layer whose main components are a leuco dye and a color developer that reacts with the leuco dye to develop color. It is recognized that water resistance, plasticizer resistance, oil resistance, and further heat sensitivity are significantly improved.

Claims (1)

[Scope of Claims] 1. A heat-sensitive recording material in which a heat-sensitive coloring layer comprising a leuco dye and a color developer that reacts with the leuco dye to form a color as main components is provided on a support, (In the formula, R ¹ , R ² , R ³ , R ⁴ , R ⁵ , R ⁶ are alkyl groups, allyl groups, aralkyl groups, alicyclic groups, hydroxyl groups,
1. A heat-sensitive recording material, characterized in that the heat-sensitive coloring layer contains at least one compound represented by an alkyl group having a hydroxyl group, a phenyl group, or a phenyl group having a substituent.