JPS61202885A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enable water resistance, plasticizer resistance, oil resistance and thermal sensitivity to be markedly enhanced, by incorporating at least one specified compound into a thermal color forming layer. CONSTITUTION:At least one compound of any of the general formulas, wherein each of R<1>, R<2>, R<3>, R<4>, R<5> and R<6> is alkyl, aryl, aralkyl, cycloalkyl, hydroxyl, hydroxy-subst. alkyl, phenyl or subst. phenyl, is incorporated in a thermal color forming layer, in a thermal recording material in which a thermal color forming layer comprising a leuco dye and a color developer for developing the color of the dye by reacting therewith as main constituents is provided on a base. By this, image stability, water resistance, plasticizer resistance, oil resistance and thermal sensitivity are enhances. The leuco dye is, for example, crystal violet lactone or 3-indolino-3-p-dimethylaminophenyl-6-dimethylaminophthalide, and the color developer is, for example, 4-phenylphenol or 4-hydorxyaceto phenone.

Description

Detailed Description of the Invention <Industrial Application Field> The present invention relates to a heat-sensitive recording material, and more specifically, a heat-sensitive recording material having a heat-sensitive color forming layer containing a leuco dye and a color developer that reacts with the dye to form a color. Concerning improving the image stability of recording materials.

<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 used as recording paper for computer output, facsimiles, recorders, etc., and also for tickets, cards, etc. When recording sheets using heat-sensitive recording materials come into contact with water, plasticizers, oil, etc. for a long period of time, the colored parts fade, and improvement is required. Dimethyl (JP 57-129785), benzophenone derivatives having SO3 groups (JP 57-199686), metal salts of benzoin compounds (JP 58-132589),
Sulfone compound (JP-A-58-205793), amide compound (JP-A-58-211495>, l, 1.3-
Tris(3-t-butyl-4-hydroxy-6-methylphenyl)-butane (JP 59-2884), anilide compound (JP 59-9092), zinc dithiocarbamate compound (JP 59-41296) ), etc., but sufficient image stability, particularly 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 color forming 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. Medium, R1% R2, R3, R
4, R5 and R6 are at least one compound represented by an alkyl group, an allyl group, an aralkyl group, an alicyclic group, a hydroxyl group, an alkyl group having a hydroxyl group, a phenyl group, or a phenyl group having a substituent in the thermal coloring layer. The present invention has been completed based on the new discovery that significant improvements in image stability, particularly water resistance, plasticizer resistance, oil resistance, and further heat sensitivity, can be obtained by containing .

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 color-forming system formed by the reaction and reduces the solubility of the color-forming compound in water, plasticizer, oil, etc.

Specific examples are shown in Table 1.

Table-1 Examples are shown in Table 2.

Table-2 Examples are shown in Table 3.

Table 3 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-indoly/-3-D-
Dimethylaminophenyl-6-dimethylaminophthalide, 3-diethylamino-7-chlorofluoran, 3-diethylamino-5-methyl-7-t-butylfluoran, 3-diethylamino-6-methyl-7-anilino Fluoran, 3-diethylamino-6-methyl-7-p-butylanilinofluorane, 3-diethylamino-7-sibenzylaminofluorane, 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-(s+-trifluoromethylanilino)fluorane, 1.3-(N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluorane, etc., but limited to these. It is not something that will be done.

Further, as a color developer that reacts with the above leuco dye to develop a color, 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
-5-di-α-methylbenzylsalicylic acid, 3-methyl-5-t-butylsalicylic acid, phthalic acid monoanilide paraethoxybenzoic acid, bis(4-hydroxyphenyl)
Examples include acetic acid ester and 4-hydroxybenzoic acid ester, but are not limited to these.

Furthermore, inorganic and organic pigments such as aluminum hydroxide, 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 as a sensitizer, for example, stearamide, palmitamide, oleic acid amide, lauric acid amide, ethylene bis stearamide, methylene bis stearamide, methylol stearamide, paraffin wax, and higher alcohols. , higher resin acids, etc. may be added.

The above-mentioned heat-sensitive components of the present invention are used as a binder to form a heat-sensitive layer on a support such as paper, synthetic paper, resin film, or a composite thereof, using a water-soluble or water-insoluble resin binder. Adhesives 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. Acid resin, styrene-maleic anhydride resin, polyacrylamide, modified polyacrylamide, carboxyl methyl cellulose, methyl vinyl ether-maleic acid copolymer, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, and as a water-soluble emulsion, vinyl acetate,
Polystyrene, acrylic ester, vinyl chloride-vinyl acetate copolymer, etc. are used alone or in combination. Furthermore, if necessary, a curing agent may be added to harden these binders to improve water resistance and chemical resistance. Further, a coating layer may be provided on the heat-sensitive coloring layer containing the compound of the present invention,
An underlayer may also be provided between the coloring layer and the support.

<Examples> The present invention will be explained in detail below using Examples. Hereinafter, parts refer to parts by weight.

A-G solutions were prepared by grinding and dispersing mixtures having the following formulations in a ball mill for one day.

Solution A 1 Water 25 parts Solution B Solution E Solution F Solution G Example f 10 parts of the above Solution A, 25 parts of Solution B, 25 parts of Solution C, 15 parts of Solution D
1 part and 25 parts of a 10% polyvinyl alcohol aqueous solution were mixed to obtain a heat-sensitive recording paint. The coating amount of the paint on high-quality paper after drying is 6g/n? A heat-sensitive layer was formed by coating and drying 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 paper obtained in Example 12.3 and Comparative Example 1.2 was colored on a 90°C hot plate, the optical images shown in Table 4 were obtained using a Macbeth reflection densitometer RD-514 model. Obtained. As shown in Table 4, the thermal recording paper obtained in the comparative example had a low coloring density and sufficient coloring could not be obtained at 90°C, so the recording paper of this comparative example was colored on a heating plate at 120°C. Water resistance, plasticizer resistance, and oil resistance were tested using the densitometer mentioned above.

The water-resistant heat-sensitive recording paper was submerged in a water tank, and the density of the colored area was measured 12 hours later.

Plasticizer resistant niblastic eraser (@Tombow Pencil PE
-01) was brought into contact with the colored part under pressure, and the density of the colored part was measured after 1 hour.

A few drops of oil resistance 0 edible soybean oil were dropped on the colored area, and after 1 hour, the oil was wiped off with gauze, and the concentration of the colored area was measured.

The results of these tests are shown in Table 4.

Table 4 <Effects of the Invention> As shown in Table 4, the compound of the present invention can be 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] 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, and a heat-sensitive recording material having a general formula ▲ mathematical formula, chemical formula, table There are ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ ▲ There are mathematical formulas, chemical formulas, tables, etc. ▼ (In the formula, R^1, R^2, R^3, R^4, R^5, R
^6 is an alkyl group, allyl group, aralkyl group, alicyclic group,
1. A heat-sensitive recording material, characterized in that the heat-sensitive coloring layer contains at least one compound represented by a hydroxyl group, an alkyl group having a hydroxyl group, a phenyl group, or a phenyl group having a substituent.