JPH06127148A - Thermal recording material - Google Patents

Abstract

PURPOSE:To enhance color forming properties and stability by adding a compd. represented by a specific formula being an electron acceptive compd. and one kind of a compd. selected from a naphthol derivative, a fatty acid amide derivative and compds. respectively represented by specific formulae being a sensitizer. CONSTITUTION:A thermal recording material is constituted by providing a thermal recording color forming layer containing a colorless or light-colored dye precursor and an electron acceptive compd. on a support. In this case, at least one kind of a compd. represented by formula is added as the electron acceptive compd. Further, as a sensitizer, at least one kind of a compd. selected from a naphthol derivative, a fatty acid amide derivative and at least one kind of a compd. selected from a group consisting of compds. represented by three formulae is added. By this constitution, the thermal recording material especially excellent in color forming properties, having high sensitivity and excellent in raw preservability and the stability of a developed color image is obtained.

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, and more particularly to a heat-sensitive recording material which is excellent in color developability, has high sensitivity, and has improved raw storage stability and color image stability.

[0002]

2. Description of the Related Art Recording materials using colorless or light-colored electron-donating dye precursors and electron-accepting compounds are already well known as pressure-sensitive paper, heat-sensitive paper, light-sensitive pressure-sensitive paper, heat-sensitive recording paper, heat-sensitive transfer paper and the like. , For example British Patent No. 2,14
0,449, U.S. Pat. Nos. 4,480,052, 4,436,920, JP-B-60-23992, JP-A-57-179836, and JP-A-60-123556.
It is described in detail in JP-A-60-123557.

Particularly, a heat-sensitive recording material is disclosed in Japanese Examined Patent Publication No. 43-416.
No. 0 and 45-14039 and the like. These thermal recording materials are applied to various fields such as facsimiles, printers and labels, and their needs are expanding. On the other hand, however, the heat-sensitive recording material has a defect that fog is caused by a solvent and the like, and a color developing material is discolored by oils and fats, chemicals, etc., so that labels, slips, word processor papers, In the field of plotter paper, etc., the product value was impaired.

The present inventors have focused their attention on the oil solubility, the solubility in water, the partition coefficient, the pKa, the polarity of the substituent, the position of the substituent, etc. of each of the electron-donating dye precursor and the electron-accepting compound. And made efforts to obtain a material for a good thermal recording material. As a result, by imparting resistance to such chemicals as described above, the sensitivity is generally significantly reduced, but by using a specific electron-accepting compound and a specific sensitizer together, extremely good results can be obtained. The inventors have found that the above can be achieved and reached the present invention. Therefore, an object of the present invention is to provide a heat-sensitive recording material having high sensitivity, good raw storability and stability of a color image, and high printing quality.

[0005]

The above objects of the present invention are as follows.
A heat-sensitive recording material comprising a support and a heat-sensitive recording color-forming layer containing an electron-donating dye precursor and an electron-accepting compound, containing at least one compound represented by Chemical formula 5 as an electron-accepting compound. In addition, as the sensitizer, at least one kind selected from the group consisting of a naphthol derivative, a fatty acid amide derivative, a compound represented by Chemical formula 6, a compound represented by Chemical formula 7, and a compound represented by Chemical formula 8 Achieved by a heat-sensitive recording material characterized by containing a compound.

[0006]

[Chemical 5] In the formula, X is a hydrogen atom, a halogen atom, a hydroxy group, a carboxyl group, an alkoxycarbonyl group, an alkoxy group, an allyl group, an aryl group, an aralkyl group, or a cycloalkyl group, and Ar is an arylene group having two or more benzene rings. R represents a hydrogen atom, an alkyl group, an aralkyl group, or an aryloxyalkyl group, each of which represents an arylene group in which two or more benzene rings are condensed or a bisarylene group linked via a divalent group.

[0007]

[Chemical 6] In the formula, R ₁ and R ₂ each represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and X represents an alkylene group which may be branched. R ₁ and R ₂ may be the same or different.

[Chemical 7] In the formula, R represents a phenyl group which may have a substituent or an aralkyl group, and X represents an alkylene group having 1 to 4 carbon atoms or -CH = CH-.

[Chemical 8] In the formula, either X or Y is an alkoxy group and the other is a halogen atom.

The electron-donating dye precursor used in the present invention is, for example, a triphenylmethanephthalide compound, a fluorane compound, a phenothiazine compound, an indolylphthalide compound, a leukoauramine compound, a rhodamine lactam compound. A known or colorless compound such as a compound, a triphenylmethane compound, a triazene compound, a spiropyran compound, or a fluorene compound can be appropriately selected and used. These electron-donating dye precursors can be used by being encapsulated in microcapsules from the viewpoint of improving the raw storage stability of the heat-sensitive recording material.

Among the electron-donating dye precursors that can be used in the present invention, specific examples of phthalides are US Reissue Pat. No. 23,024 and US Pat. No. 3,491,111.
Issue No. 3,491,112 Issue 3,491,11
No. 6 and No. 3,509,174, and specific examples of fluoranes are U.S. Pat. Nos. 3,624,107 and 3,6.
27,787, 3,641,011 and 3,
462,828, 3,681,390, 3,920,510, 3,959,571, and specific examples of spiro dipyrans are described in U.S. Pat. No. 3,971,80.
No. 8, pyridine-based and pyrazine-based compounds are described in U.S. Pat. Nos. 3,775,424 and 3,853,869.
No. 4,246,318 and specific examples of fluorene compounds are described in JP-A-61-240989.

Among them, 2-arylamino-3-H that develops black color, a halogen- or alkyl-6-substituted aminofluorane compound is particularly effective. Specific examples thereof include 2-anilino-3-methyl-6-diethylaminofluorane and 2-anilino-3-methyl-6-N.
-Cyclohexyl-N-methylaminofluorane, 2-
p-chloroanilino-3-methyl-6-dibutylaminofluorane, 2-anilino-3-chloro-6-diethylaminofluorane, 2-anilino-3-methyl-6-N
-Ethyl-N-isoamylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-dodecylaminofluorane, 2-o-chloroanilino-6-dibutylaminofluorane, 2-anilino-3- Pentadecyl-
6-diethylaminofluorane, 2-anilino-3-ethyl-6-dibutylaminofluorane, 2-o-toluidino-3-methyl-6-diisopropylaminofluorane, 2-anilino-3-methyl-6-N- Isobutyl-
N-ethylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfurylaminofluorane, 2-anilino-3-chloro-6-N-ethyl-N-isoamylaminofluorane , 2-anilino-3-methyl-6-N-methyl-N-γ-ethoxypropylaminofluorane, 2-anilino-3-methyl-6
-N-ethyl-N-γ-ethoxypropylaminofluorane, 2-anilino-3-methyl-6-N-ethyl-N
Examples include -γ-propoxypropylaminofluorane and 2-anilino-3-methyl-6-N-methyl-N-propylaminofluorane.

X in the electron-accepting compound represented by the above chemical formula 5 used in the present invention is preferably a hydrogen atom, a hydroxy group, a carboxyl group, a methoxycarbonyl group, an ethoxycarbonyl group, a normal propoxycarbonyl group or an isopropoxycarbonyl group. An alkoxycarbonyl group having 1 to 7 carbon atoms such as a group, a normal butylcarbonyl group,
Isobutyloxycarbonyl group, chlorine atom, methyl group,
1 carbon atom such as ethyl group, normal propyl group, isopropyl group, tertiary butyl group, secondary butyl group
To C5 alkyl groups, methoxy groups, ethoxy groups, and other C1-5 alkoxy groups, allyl groups, phenyl groups, and other C7-10 aryl groups, and benzyl groups and other C7 to 1 carbon atoms.
5 to 7 carbon atoms such as aralkyl group of 0, cyclohexyl group, etc.
And the cycloalkyl group, α-phenylpropyl group, and α-phenylallyl group are preferable.

The group represented by Ar is preferably a condensed ring or a divalent group represented by the following chemical formula 9.

[Chemical 9] In the formula, Y represents a single bond, an alkylene group having 1 to 10 carbon atoms, a phenylene group, an oxygen atom, a sulfur atom, a carbonyl group or a sulfone group. X has the same meaning as X in Chemical formula 5.

Of these, particularly preferred groups are:
2,7-naphthylene group, 1,5-naphthylene group, anthracenylene group and Y in the chemical formula 9 is a single bond, methylene group, ethylene group, isopropylidene group, butylene group, phenylene group, oxygen atom, sulfur atom, Examples thereof include those having a carbonyl group or a sulfone group. As R in Chemical formula 5, a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aralkyl group having 7 to 20 carbon atoms and an aryloxyalkyl group having 8 to 20 carbon atoms are preferable.

Examples of the alkyl group having 1 to 10 carbon atoms include methyl group, ethyl group, normal propyl group, isopropyl group, normal butyl group, tertiary butyl group,
Secondary butyl group, isobutyl group, normal amyl group, isoamyl group, normal hexyl group, normal octyl group, and aralkyl group having 7 to 20 carbon atoms include benzyl group, paramethylbenzyl group, paraethylbenzyl group, para-normalpropylbenzyl group. Groups, para-isopropylbenzyl group, methoxybenzyl group, chlorobenzyl group, phenethyl group, phenylpropyl group, naphthylmethyl group, aryloxyalkyl group having 8 to 20 carbon atoms, such as phenoxyethyl group, methoxyphenoxyethyl group, chlorophenoxy group. Ethyl group, methylphenoxyethyl group, 1-methyl-2-phenoxyethyl group, 1-methyl-2- (methoxyphenoxy) ethyl group, 1-methyl-2- (methylphenoxy) ethyl group, 2-naphthoxyethyl group, 1 -Naft Shiechiru group, 1-methyl-2-
A (2-naphthoxy) ethyl group is preferred.

Specific examples of the compound represented by Chemical formula 5 are:
For example, the compounds of the following chemical formulas 10 to 24 can be mentioned.

[Chemical 10]

[Chemical 11]

[Chemical 12]

[Chemical 13]

[Chemical 14]

[0016]

[Chemical 15]

[Chemical 16]

[Chemical 17]

[Chemical 18]

[Chemical 19]

[0017]

[Chemical 20]

[Chemical 21]

[Chemical formula 22]

[Chemical formula 23]

[Chemical formula 24] Hydrates of the above compounds can also be used in the present invention.

The melting point of the compound represented by Chemical formula 5 can be controlled by incorporating water or an organic solvent into the crystal. For example, the compound of formula 11 is usually 195-
Although it has a melting point of 196 ° C., when two molecules of water are added as water of crystallization, it has a melting point of 100 ° C. Therefore, by using this, it is possible to improve the thermal sensitivity. The dispersed particle size of the electron-accepting compound in the present invention after atomization by a sand mill or the like is 3 from the viewpoint of obtaining color development sensitivity.
It is preferably not more than μm, and particularly preferably atomized to not more than 2 μm.

In the present invention, the well-known electron such as salicylic acid derivative, metal salt of aromatic carboxylic acid, phenol derivative, phenol resin, novolac resin, metal-treated novolac resin, metal complex, acid clay, bentonite, etc. You may use together an accepting compound. Examples of these are Japanese Examined Patent Publication Nos. 40-9309 and 45-14039.
No. 52-14048, 48-51510.
No. 57-210886, No. 58-87089,
No. 59-112286, No. 60-176795, No. 61-95988, and the like.

Specific examples of these include 4-tert-butylphenol, 4-phenylphenol, 2,2'-dihydroxybiphenyl, 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 4, 4'-sec-butylidene diphenol,
4,4'-cyclohexylidene diphenol, bis (3
-Aryl-4-hydroxyphenyl) sulfone, 4-
Hydroxyphenyl-3 ', 4'-dimethylphenyl sulfone, 4- (4-isopropoxyphenylsulfonyl) phenol, 4,4'-dihydroxydiphenyl sulfide, 1,4-bis- (4'-hydroxycumyl) benzene, 1,3-bis- (4'-hydroxycumyl) benzene, 4,4'-thiobis (6-tert-butyl-3-methylphenol), 1,1,3-tris (2-methyl-4-hydroxy) -5-tert-butylphenyl) butane, 4,4'-butylidene-bis- (3
-Methyl-6-tert-butylphenol), 4,
There are 4′-dihydroxydiphenyl sulfone, 4-hydroxybenzoic acid benzyl ester and the like.

The electron-accepting compound is preferably used in an amount of 50 to 800% by weight, more preferably 100 to 500% by weight based on the electron-donating dye precursor. The electron-accepting compound represented by Chemical Formula 5 of the present invention has good solvent resistance, but has a drawback that when a general sensitizer is used, the color developability when printing with low energy is poor. is there.
However, especially as sensitizers, naphthol derivatives,
The above-mentioned drawbacks are eliminated by using an aliphatic amide derivative and a compound selected from the group represented by Chemical formulas 6 to 8.

Specific examples of the naphthol derivative which can be used as the above-mentioned sensitizer include, for example, JP-A-5-56.
No. 8-87094. The aliphatic amide derivative used as a sensitizer in the present invention has a general formula R ₁ C.
It is represented by ONH-X. Here, R ₁ is C ₁₂ -C ₂₀ alkyl, and X is a hydrogen atom or CH ₂ OH. In addition, specific examples of the sensitizer represented by Chemical Formula 6 include JP-A-6
In addition to those described in 0-56588, for example,
Examples thereof include 1,2-bis- (4-methoxyphenoxy) propane and the like described in JP-A-2-70481.

Specific examples of the sensitizer represented by Chemical formula 7 are:
The sensitizers described in JP-A No. 64-1583 and JP-B No. 2-51747, and the sensitizer represented by Chemical Formula 8 include:
For example, 4-chlorobenzyl-4'-methoxyphenyl ether, 4-methoxybenzyl-4'-chlorophenyl ether and the like described in JP-A-2-184489 can be mentioned.

In the present invention, together with the above-mentioned sensitizer,
Other known sensitizers can be used in combination. Examples of sensitizers that can be used in combination include JP-A-58-57989 and JP-A-5-57989.
Examples thereof include compounds disclosed in 8-87094 and 63-39375. Aromatic ethers (particularly benzyl ethers, di (substituted phenoxy) alkanes), esters and / or aliphatic amides, aromatic amides or ureas are representative. In particular, it is preferable to use an aliphatic amide, an aromatic amide or urea together.

Next, a method for producing a typical thermosensitive coloring layer of the present invention will be described. The electron-donating dye precursor, the electron-accepting compound and the sensitizer are dispersed together with a water-soluble polymer aqueous solution such as polyvinyl alcohol to a size of several microns or less using a ball mill, a sand mill or the like. The sensitizer is added to either or both of the electron-donating dye precursor and the electron-accepting compound, and is dispersed at the same time, or in some cases, a eutectic with the electron-donating dye precursor or the electron-accepting compound is previously prepared. It may be produced and dispersed. These dispersions are mixed after dispersion and, if necessary, pigments, surfactants, binders, metal soaps, waxes, antioxidants, ultraviolet absorbers and the like are added to obtain a heat-sensitive coating liquid.

The obtained heat-sensitive coating liquid is applied to high-quality paper, high-quality paper having an undercoat layer, synthetic paper, plastic film, etc. and dried, and then imparted with smoothness by a calendering treatment to obtain a desired heat-sensitive recording material. Becomes At this time, JIS-8
119 has a smoothness of 500 seconds or more, especially 80
It is particularly preferable to use a support for 0 seconds or more from the viewpoint of dot reproducibility. In order to obtain a support having a smoothness of 500 seconds or more, (1) a highly smooth one such as synthetic paper or a plastic film is used, and (2) an undercoat layer containing a pigment as a main component on the support. And (3) using a super calender or the like to increase the smoothness of the support.

The binder is preferably a compound which dissolves in water at 25 ° C. in an amount of 5% by weight or more.
Polyvinyl alcohol (including modified polyvinyl alcohol such as alkyl modified, carboxy modified, itaconic acid modified, maleic acid modified, sulfonic acid modified, and silica modified), methyl cellulose, carboxymethyl cellulose, starches (including modified starch), gelatin, gum arabic , Casein, hydrolyzate of styrene-maleic anhydride copolymer, polyacrylamide, saponified product of vinyl acetate-polyacrylic acid copolymer, and the like.

These binders are not only dispersed,
Used for the purpose of improving coating strength, for this purpose styrene-butadiene copolymer, vinyl acetate copolymer, acrylonitrile-butadiene copolymer, methyl acrylate-butadiene copolymer, polychlorinated A synthetic polymer latex binder such as vinylidene can also be used in combination. Further, if necessary, a cross-linking agent for the binder may be added depending on the kind of the binder.

Examples of pigments include calcium carbonate, barium sulfate, lithopone, wax, kaolin, silica and amorphous silica. As the metal soap, higher fatty acid metal salts are used, such as zinc stearate, calcium stearate, and aluminum stearate. If necessary, a surfactant, an antistatic agent, an ultraviolet absorber, an antifoaming agent, a conductive agent, a fluorescent dye, a coloring dye, etc. may be added.

If desired, a protective layer may be provided on the thermosensitive coloring layer. Any known protective layer can be used as the protective layer for the heat-sensitive recording material. Further, if necessary, a back coat layer may be provided on the surface of the support of the heat-sensitive recording material opposite to the heat-sensitive color developing layer.
As the back coat layer, any one known as a back coat layer of a thermal recording material can be used. The applied heat-sensitive recording material is dried and then treated with a calender or the like before use.

[0031]

As described in detail above, since the heat-sensitive recording material of the present invention is used in combination with a special electron-accepting compound and a sensitizer, it is possible to improve chemical resistance without lowering thermal sensitivity. You can

[0032]

EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited thereto.
However, "%" represents% by weight.

Examples 1-12, Comparative Examples 1-10 As an electron-donating dye precursor, 2-anilino-3-methyl-6-N-ethyl-N-tetrahydrofurfurylaminofluorane, an electron-accepting compound and As a sensitizer, 2 g of each of the sensitizers listed in Table 1 was dispersed together with 100 g of a 5% polyvinyl alcohol (PVA-105: trade name of Kuraray Co., Ltd.) aqueous solution for one day and night to give an average particle size of 1.5.
It was made to be not more than μm to obtain each dispersion.

80 g of calcium carbonate was added to hexame
Homogenize with 160 g of sodium taurate 0.5% solution
To obtain a pigment dispersion. Made as above
5 g of the electron-donating dye precursor dispersion liquid,
Electron-accepting compound dispersion liquid 10 g, sensitizer dispersion liquid 5 g, charcoal
Calcium acid dispersion liquid is mixed at a ratio of 5 g and further mixed with 21%
Thermosensitive coloring layer by adding 3 g of zinc thearate emulsion
A coating liquid was obtained. This thermosensitive color developing layer coating solution is used to weigh 50 g / m 2.
²The dry weight of the coating layer is 5g / m on high quality paper. ²become
Apply using a wire bar and dry at 50 ° C for 1 minute
It was dried to obtain a thermosensitive recording paper.

[0035]

[Table 1]

The heat-sensitive recording paper obtained as described above was surface-treated with a calender and adjusted so that the smoothness was 300 ± 50 seconds as Beck's smoothness to obtain a heat-sensitive recording material. The heat-sensitive recording material thus obtained was evaluated as follows. (1) The color density was measured with a Macbeth densitometer using a printing tester manufactured by Kyocera Co., Ltd., when the printing energy was 30 mJ / mm ² . The higher this value, the higher the sensitivity as a thermal recording material. (2) The chemical resistance test was conducted by impregnating filter paper with ethanol and a plasticizer (dioctyl phthalate) respectively, and overlaying it on the color-developing surface of the recording paper obtained by the above-mentioned method to erase the fog on the white background and the color-developing part. The evaluation was performed by evaluating the degree of color (discoloration). The above results are as shown in Table 2.

[0037]

[Table 2] As can be seen from the results in Table 2, the recording material of the present invention has high sensitivity and does not cause fog coloration or decolorization of the color-developed portion due to chemicals, and has extremely excellent performance.

[Chemical 25]

[Chemical formula 26]

[Chemical 27]

[Chemical 28]

[Chemical 29]

[Chemical 30]

[Chemical 31]

[Chemical 32]

[Chemical 33]

Claims (1)

[Claims] 1. A heat-sensitive recording material comprising a support and a thermosensitive recording color-forming layer containing a colorless or light-colored electron-donating dye precursor and an electron-accepting compound, represented by Chemical Formula 1 as an electron-accepting compound. And a naphthol derivative, a fatty acid amide derivative, a compound represented by Chemical formula 2, a compound represented by Chemical formula 3, and a compound represented by Chemical formula 4 as a sensitizer. A heat-sensitive recording material containing at least one compound selected from the above. [Chemical 1] In the formula, X is a hydrogen atom, a halogen atom, a hydroxy group, a carboxyl group, an alkoxycarbonyl group, an alkoxy group, an allyl group, an aryl group, an aralkyl group, or a cycloalkyl group, and Ar is an arylene group having two or more benzene rings. R represents a hydrogen atom, an alkyl group, an aralkyl group, or an aryloxyalkyl group, each of which represents an arylene group in which two or more benzene rings are condensed or a bisarylene group linked via a divalent group. [Chemical 2] In the formula, R ₁ and R ₂ each represent a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom, and X represents an alkylene group which may be branched. R ₁ and R ₂ may be the same or different. [Chemical 3] In the formula, R represents a phenyl group which may have a substituent or an aralkyl group, and X represents an alkylene group having 1 to 4 carbon atoms or -CH = CH-. [Chemical 4] In the formula, either X or Y is an alkoxy group and the other is a halogen atom.