Developer and thermal recording material

Abstract

To provide a thermal recording material that achieves reduced environmental load by using isolated lignin and ensures excellent alcohol resistance in printed portions.SOLUTION: A thermal recording material comprises a developer represented by formula (1) and isolated lignin. (In formula (1), a, A, and L are as defined below. a is an integer selected from 1 to 5; A independently represents a fluoro group or a perfluoroalkyl group; L is any functional group represented by formula (2). In formula (2), R is an alkyl group having 1 to 4 carbon atoms. The symbol * indicates the bonding site to the sulfur atom in formula (1)).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a color developer and a heat-sensitive recording material. [Background technology]

[0002] Generally, colorless or light-colored basic (electron-donating) leuco dyes (hereinafter referred to as "dyes") (hereinafter referred to as "developer") and an electron-accepting developer that reacts with the dye to produce color when heated. Thermal recording materials having a thermal recording layer mainly composed of a thermal recording agent (sometimes abbreviated as "thermal recording agent") are widely used. It is being put to use.

[0003] Many of the compounds used in these developers are 2,2-bis(4-hydroxyphenyl )propane (bisphenol A), bis(4-hydroxyphenyl)sulfone (bisphenol On the other hand, phenol is a compound that mainly consists of a phenol structure, such as phenol S. Due to the toxicity and environmental risks caused by the skeleton, compounds that do not have a phenol structure are used as color developers. The use of alcohol-based disinfectants is also being considered. In places where alcohol is used frequently, thermal recording media with high alcohol resistance in the printed area are required.

[0004] For example, Patent Document 1 discloses a method for producing a color developing agent using a compound having a specific sulfonylurea structure as a color developer. The thermal recording medium used had good color development sensitivity and was heat-resistant, plasticizer-resistant, moisture-resistant, and water-resistant. The durability of the printed area has been confirmed through various durability tests such as resistance to alcohol, oil, and grease. It has been disclosed that this is good. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2021 / 107037 Summary of the Invention [Problem to be solved by the invention]

[0006] According to the studies of the present inventors, it has been found that the sulfonylurea structure shown in the above-mentioned Patent Document 1 is A thermal recording material having good durability of the printed portion when a specific compound having the above properties is used as a developer. However, a higher level of alcohol resistance is required. The object of the present invention is to reduce the environmental impact by using isolated lignin and to improve the resistance of the printed part to alcohol. The object of the present invention is to provide a heat-sensitive recording material having excellent sealing properties. [Means for solving the problem]

[0007] As a result of intensive research by the present inventors, it has become possible to develop a method for producing a thermal recording material using a specific color developer and a thermal recording material containing isolated lignin. It has been found that the above-mentioned problems can be solved by the above-mentioned. It is.

[0008] [1] A heat-sensitive recording material comprising a developer represented by the following formula (1) and isolated lignin: [ka] (In the above formula (1), a, A, and L are as follows. a is an integer selected from 1 to 5; Each A is independently a fluoro group or a perfluoroalkyl group; L is any functional group represented by the following formula (2). [ka] In the above formula (2), R is an alkyl group having 1 to 4 carbon atoms. * is the sulfur atom in formula (1) The binding site is indicated.) [2] The color developer according to [1], wherein in formula (1), a is 1 or 2. [3] The compound according to [1] or [2], wherein A is substituted at the m-position or p-position in the formula (1). Developer. [4] The color developer according to [3], wherein A is substituted at the m-position in formula (1). [5] The color developer according to [3] or [4], wherein in formula (1), a is 1. [6] In the formula (1), A is a fluoro group or a trifluoromethyl group [1] to [5]. 2. The developer according to claim 1 . [7] In the formula (1), L is a phenyl group, an o-toluyl group, a m-toluyl group, or a p-toluyl group. The color developer according to any one of [1] to [6], wherein the color developer is selected from any one of a group consisting of a aryl group and a aryl group. [8] The isolated lignin is kraft lignin or enzymatically decomposed lignin, 7] The developer according to any one of the above items. [9] The heat-sensitive recording material according to any one of [1] to [8], wherein the heat-sensitive recording layer contains a sensitizer. .

[10] The weight ratio of the developer to the isolated lignin (developer / isolated lignin) is 40 / 60 to 9 The heat-sensitive recording material according to any one of [1] to [9], wherein the ratio of the refractive index to the refractive index is 0 / 10. Effect of the Invention

[0009] According to the present invention, there is provided a heat-sensitive recording material having excellent color development sensitivity and alcohol resistance of the printed portion. can be.

[0010] The present invention will be described in detail below, but the present invention is not limited to the following description. The present invention can be modified and embodied in any manner without departing from the spirit and scope of the invention. In an invention, when "~" is used to express numerical values ​​or physical properties, This will be used to include the latter value.

[0011] [Thermal recording material] The heat-sensitive recording material of the present invention is a heat-sensitive recording material having a heat-sensitive recording layer, The thermal recording material contains a specific color developer and isolated lignin. The thermal recording layer of the thermal recording material may be any of a film, a synthetic paper, a card, etc. The support may be provided on the substrate, and may have a protective layer, an underlayer, or a barrier layer, if necessary, as described later. Here, "on the support" means at least one of the supports. "Installed on a support" refers to the surface of the support that is covered by the adhesive. At least a part of the layer may be present.

[0012] [Thermal recording layer] The heat-sensitive recording material according to an embodiment of the present invention has a heat-sensitive recording layer, The thermal recording layer contains a developer and isolated lignin, as well as leuco Dyes, developers other than those mentioned above (hereinafter sometimes referred to as "other developers"), sensitizers The binder may contain stabilizers, crosslinking agents, pigments, lubricants, and other additives.

[0013] [Developer] The color developer according to the first embodiment of the present invention is a color developer containing a compound represented by the following formula (1): do. [ka] (In the above formula (1), a, A, and L are as follows. a is an integer selected from 1 to 5; Each A is independently a fluoro group or a perfluoroalkyl group; L is any functional group represented by the following formula (2). [ka] In the above formula (2), R is an alkyl group having 1 to 4 carbon atoms. * is the sulfur atom in formula (1) The binding site of

[0014] The color developer according to the first embodiment of the present invention has a remarkable effect of being excellent in color development sensitivity and storage stability. The reason why the above-mentioned developer exhibits such excellent effects is believed to be as follows. That is, a fluoro group or a perfluoro group is used as a substituent for a sulfonylurea compound. The introduction of an orthoalkyl group increases the acidity and / or hydrogen bond donating ability of the NH moiety. The color sensitivity is improved by improving the sensitivity of the leuco dye, and the color development state is stabilized. This is thought to be because the storage stability is improved by converting the fluorine group or By having a perfluoroalkyl group, association and / or crystallinity are appropriately suppressed. By doing so, amorphous stability can be effectively maintained without lowering the energy required for melting too much. This is believed to be because the temperature can be increased, thereby improving the storage stability of the metastable color-developed state. In addition, by having a fluoro group or a perfluoroalkyl group as a substituent, High color development due to appropriate adjustment of the molecular level miscibility (compatibility) with dyes and sensitizers It is believed that both sensitivity and storage stability can be achieved. In addition, due to the highly polar sulfonylurea group, The hydrophilic portion is a molecular weight that is derived from the hydrophilic portion and the hydrophobic portion is a molecular weight that is derived from the fluoro or perfluoroalkyl group. It is believed that by having this inside, storage stability can be improved simultaneously under various storage conditions. Specifically, it is possible to improve resistance to moisture and water while at the same time improving resistance to oil and grease. It is believed that resistance can be increased to a high level at the same time.

[0015] In the above formula (1), a is an integer selected from 1 to 5, preferably 3 or less, more preferably It is preferably 2 or less, and particularly preferably 1. When a is large, the hydrophobicity increases, and the hydrophobicity in water is improved. The dispersibility of the polymer in the polymer solution decreases, and the molecular weight increases, making it difficult for the polymer to move during melting. It is believed that the compatibility with leuco dyes and sensitizers is too low, resulting in a decrease in color development performance. . In the above formula (1), the perfluoroalkyl group in A has 1 to 12 carbon atoms. Preferably, the carbon number is 6 or less, more preferably 4 or less, and particularly preferably 1 carbon atom (trifluoro Perfluoroalkyl groups with a large number of carbon atoms are too hydrophobic and cannot be dissolved in water. The dispersibility of the polymer decreases, and the molecular weight increases, making it difficult for the polymer to move when melted. It is believed that the color development performance is reduced due to an excessive decrease in compatibility with the leuco dye and the sensitizer. Each A is independently a fluoro group or a perfluoroalkyl group, but when a is 2 or more, In this case, all A's may be the same or different substituents, and all A's may be the same substituent. It is more preferable that A is full-flavoured since it provides suitable hydrophobicity and compatibility. Among them, a fluoromethyl group or a trifluoromethyl group is preferred, and high color development sensitivity is achieved due to high compatibility. Due to ease of realization, the trifluoromethyl group is particularly preferred.

[0016] The substitution position of the fluoro group or perfluoro group in A is not particularly limited. The o- or m-position is preferred because it suppresses the formation of the cyclic ring and provides suitable amorphous stability. and is spatially separated from adjacent NH sites so as not to inhibit reactivity with the leuco dye. Therefore, the m-position or p-position is preferable. Therefore, the m-position is particularly preferred. When a is 2 or more, at least one A is at the m-position. It is preferable that there is.

[0017] L is any functional group represented by the above formula (2), i.e., a phenyl group and a mono-substituted phenyl group. The functional group is any one selected from the group consisting of a group. In the above formula (2), R is an alkyl group having 1 to 4 carbon atoms, and thermal motion is suppressed and storage stability is ensured. Since the aryl group is easily improved in the polymerization property, a methyl group or an ethyl group is preferable, and a methyl group is particularly preferable. I wish. The functional group represented by the above formula (2) is preferably a phenyl group, an o-tolyl group, an m-tolyl group, It is a p-tolyl group or a p-tolyl group.

[0018] In a particularly preferred embodiment of the color developer according to the first aspect of the present invention, in the above formula (1), a is 2 or less, A is a fluoro group or a perfluoro group having 4 or less carbon atoms, Alternatively, the substitution position of the perfluoro group is the m-position or the p-position, and in the above formula (2), R is It is a phenyl group or an ethyl group.

[0019] Specific examples of the above formula (1) include, but are not limited to, the following. [ka] [ka]

[0020] The thermal recording material according to the embodiment of the present invention contains isolated lignin. It is lignin isolated by modifying it. Among isolated lignins, the most widely used are The lignins being used are called industrial lignins, and include lignosulfonic acid (salts), kraft lignin, etc. , soda lignin, soda-anthraquinone lignin, organosol lignin, explosive lignin The lignin, sulfate lignin, and lignin isolated by enzymatic decomposition (hereinafter referred to as "enzymatic decomposition") were Among these, kraft lignin or enzymatically decomposed lignin is the most popular. The enzymatic decomposition of lignin is preferable because it improves the alcohol resistance of the recorded portion. This is more preferable in that no sulfur remains due to the oxidation, and color development of the coating liquid can be suppressed.

[0021] Enzymatically decomposed lignin includes lignin derived from wood flour, lignin derived from bamboo, and lignin derived from straw. Examples of lignin include lignin derived from corn cobs.

[0022] The thermal recording material according to the embodiment of the present invention has excellent color development sensitivity and alcohol resistance of the printed portion. The above-mentioned thermal recording material has the following remarkable effect: The following reasons are presumed to be the cause. The colored state formed by the reaction of the developer and the leuco dye is an amorphous state in which reversible reactions also occur. It is a metastable state and is easily inhibited by external factors. For example, contact with alcohol When the developer is dissolved in the alcohol or crystallizes, it bonds with the leuco dye. The junction is cut and the color disappears. Developers that have sulfonylurea or urea groups to make them less soluble in alcohol A compound with a large molecular weight by designing it to have three or more benzene rings (for example, PF -201 and Nippon Soda's NKK-1304, etc.) improve alcohol resistance but reduce color sensitivity. I end up doing this. In order to achieve color development sensitivity, the use of a color developer having a sulfonylurea group or a urea group is also used. Known color developers designed with two or less ZEN rings easily lose their color when they come into contact with alcohol. On the other hand, the polymer structure of isolated lignin reduces its affinity with alcohol, which is an external factor. This prevents the intrusion of alcohol and stabilizes the bond between the leuco dye and the developer. Therefore, it is assumed that the color is difficult to erase. However, it is not possible to simply combine the above-mentioned known color developer designed to have two or less benzene rings with isolated lignin. Combining these two substances leads to a significant decrease in color development sensitivity. The color developer represented by formula (1) having a fluoro group or a perfluoroalkyl group of the present design is The electron-withdrawing function activates the NH color-forming site and improves compatibility with leuco dyes. Compared to the above-mentioned color developers, it can fully demonstrate color development sensitivity, and therefore can be used in combination with isolated lignin. Therefore, the sensitivity is not decreased and the alcohol resistance can be improved.

[0023] The isolated lignin may be used alone or in combination of two or more kinds. In the case of using the developer, the weight ratio of the developer to the isolated lignin (developer / isolated lignin) is preferably The ratio is preferably 40 / 60 to 90 / 10, and more preferably 50 / 50 to 70 / 30.

[0024] [Leuco dyes] In this embodiment, the heat-sensitive recording layer preferably contains a leuco dye. It is usually basic, and any of those conventionally known in the field of pressure-sensitive or heat-sensitive recording paper can be used. Specific examples of leuco dyes include triphenylmethane leuco dyes and fluoran leuco dyes. Preferred are leuco dyes, fluorene-based leuco dyes, and divinyl-based leuco dyes. Specific examples of colorless or pale-colored dyes (dye precursors) are shown below. The icosyl dye precursor may be used alone or in combination of two or more. The leuco dye is used in an amount of 10 to 200 parts by weight per 100 parts by weight of the developer of formula (1). It is preferably 15 to 150 parts by weight, more preferably 20 to 10 0 parts by weight.

[0025] Triphenylmethane leuco dyes include 3,3-bis(p-dimethylaminophenyl 3,3-(dimethylamino)phthalide [also known as crystal violet lactone] Bis(p-dimethylaminophenyl)phthalide [also known as malachite green lactone], etc. Some examples include:

[0026] Fluoran leuco dyes include 3-diethylamino-6-methylfluoran; Diethylamino-6-methyl-7-anilinofluoran; 3-Diethylamino-6-methyl 3-Diethylamino-6-methyl- 7-Chlorofluoran; 3-Diethylamino-6-methyl-7-(m-trifluoromethyl) 3-Diethylamino-6-methyl-7-(o-chloroanilino)fluoran; ) Fluoran; 3-Diethylamino-6-methyl-7-(p-chloroanilino) Fluoran 3-Diethylamino-6-methyl-7-(o-fluoroanilino)fluoran Diethylamino-6-methyl-7-(m-methylanilino)fluoran; 3-Diethylamino 3-Diethylamino-6-methyl -7-Octylaminofluoran;3-Diethylamino-6-methyl-7-benzylamine 3-Diethylamino-6-methyl-7-dibenzylaminofluoran;3 -Diethylamino-6-chloro-7-methylfluoran;3-Diethylamino-6-chloro 3-Diethylamino-6-chloro-7-methylanilinofluoran; Nofluoran;3-Diethylamino-6-ethoxyethyl-7-anilinofluoran;3 -Diethylamino-7-methylfluoran; 3-Diethylamino-7-chlorofluoran ;3-Diethylamino-7-(m-trifluoromethylanilino)fluoran;3-Diethylamino 3-Diethylamino-7-(p- 3-Diethylamino-7-(o-fluoroanilino)fluoran Fluoran;3-Diethylamino-benzo[a]fluoran;3-Diethylamino-benzo[ c] Fluoran; 3-dibutylamino-6-methyl-fluoran; 3-dibutylamino- 6-Methyl-7-anilinofluoran; 3-Dibutylamino-6-methyl-7-(o,p -Dimethylanilino)fluoran;3-Dibutylamino-6-methyl-7-(o-chloro 3-Dibutylamino-6-methyl-7-(p-chloroanilino)fluoran Fluoran; 3-dibutylamino-6-methyl-7-(o-fluoroanilino)fluoran 3-Dibutylamino-6-methyl-7-(m-trifluoromethylanilino)fluoro Fluoran;3-Dibutylamino-6-methyl-chlorofluoran;3-Dibutylamino-6- Ethoxyethyl-7-anilinofluoran; 3-dibutylamino-6-chloro-7-anilinofluoran Linofluoran; 3-dibutylamino-6-methyl-7-p-methylanilinofluoran ;3-Dibutylamino-7-(o-chloroanilino)fluoran;3-Dibutylamino- 7-(o-Fluoroanilino)fluoran; 3-Dipentylamino-6-methyl-7- Anilinofluoran; 3-dipentylamino-6-methyl-7-(p-chloroanilino ) Fluoran; 3-di-pentylamino-7-(m-trifluoromethylanilino)fluoran Fluoran;3-Dipentylamino-6-chloro-7-anilinofluoran;3-Dipentylamino 3-Pyrrolidino-6-methyl-7-(p-chloroanilino)fluoran -Anilinofluoran; 3-piperidino-6-methyl-7-anilinofluoran; 3-( N-methyl-N-propylamino)-6-methyl-7-anilinofluoran;3-(N- Methyl-N-cyclohexylamino)-6-methyl-7-anilinofluoran;3-(N -Ethyl-N-cyclohexylamino)-6-methyl-7-anilinofluoran;3-( N-ethyl-N-xylamino)-6-methyl-7-(p-chloroanilino)fluoran ;3-(N-ethyl-p-toluidino)-6-methyl-7-anilinofluoran;3-( N-ethyl-N-isoamylamino)-6-methyl-7-anilinofluoran;3-(N -Ethyl-N-isoamylamino)-6-chloro-7-anilinofluoran;3-(N- Ethyl-N-tetrahydrofurfurylamino)-6-methyl-7-anilinofluoran; 3-(N-ethyl-N-isobutylamino)-6-methyl-7-anilinofluoran;3 -(N-ethyl-N-ethoxypropylamino)-6-methyl-7-anilinofluoran ;3-Cyclohexylamino-6-chlorofluoran;2-(4-oxahexyl)-3 -Dimethylamino-6-methyl-7-anilinofluoran;2-(4-oxahexyl) -3-Diethylamino-6-methyl-7-anilinofluoran;2-(4-oxahexyl 3-Dipropylamino-6-methyl-7-anilinofluoran;2-Methyl-6- p-(p-Dimethylaminophenyl)aminoanilinofluoran;2-Methoxy-6-p -(p-Dimethylaminophenyl)aminoanilinofluoran;2-Chloro-3-methyl -6-p-(p-phenylaminophenyl)aminoanilinofluoran;2-chloro-6 -p-(p-dimethylaminophenyl)aminoanilinofluoran;2-nitro-6-p -(p-Diethylaminophenyl)aminoanilinofluoran; 2-Amino-6-p-( p-Diethylaminophenyl)aminoanilinofluoran;2-Diethylamino-6-p -(p-Diethylaminophenyl)aminoanilinofluoran;2-Phenyl-6-methyl 2-Benzyl -6-p-(p-phenylaminophenyl)aminoanilinofluoran;2-hydroxy -6-p-(p-phenylaminophenyl)aminoanilinofluoran;3-methyl-6 -p-(p-Dimethylaminophenyl)aminoanilinofluoran;3-Diethylamino -6-p-(p-diethylaminophenyl)aminoanilinofluoran;3-Diethylamino 2,4-Diamino-6-p-(p-dibutylaminophenyl)aminoanilinofluoran methyl-6-[(4-dimethylamino)anilino]fluoran, and the like.

[0027] Fluorene leuco dyes include 3,6,6'-tris(dimethylamino)spiro[ Fluorene-9,3'-phthalide];3,6,6'-tris(diethylamino)spiro[ fluorene-9,3'-phthalide], and the like.

[0028] Divinyl leuco dyes include 3,3-bis[2-(p-dimethylaminophenyl) -2-(p-methoxyphenyl)ethenyl]-4,5,6,7-tetrabromophthalide; 3,3-Bis[2-(p-dimethylaminophenyl)-2-(p-methoxyphenyl) ether 3,3-bis[1,1-bis(4-thenyl]-4,5,6,7-tetrachlorophthalide; pyrrolidinophenyl)ethylene-2-yl]-4,5,6,7-tetrabromophthalide; 3,3-Bis[1-(4-methoxyphenyl)-1-(4-pyrrolidinophenyl)ethyl] phenyl-2-yl]-4,5,6,7-tetrachlorophthalide, and the like.

[0029] Other leuco dyes include 3-(4-diethylamino-2-ethoxyphenyl)- 3-(1-ethyl-2-methylindol-3-yl)-4-azaphthalide;3-(4- Diethylamino-2-ethoxyphenyl)-3-(1-octyl-2-methylindole -3-yl)-4-azaphthalide;3-(4-cyclohexylethylamino-2-methoxy (1-ethyl-2-methylindol-3-yl)-4-azaphthalyl 3,3-Bis(1-ethyl-2-methylindol-3-yl)phthalide;3,6- Bis(diethylamino)fluoran-γ-(3'-nitro)anilinolactam;3,6- Bis(diethylamino)fluoran-γ-(4'-nitro)anilinolactam;1,1- Bis[2',2',2”,2”-tetrakis-(p-dimethylaminophenyl)-ethenyl 1,1-bis[2',2',2”,2”-tetrakis(nitrile)-2,2-dinitrileethane; -(p-Dimethylaminophenyl)-ethenyl]-2-β-naphthoylethane;1,1- Bis[2',2',2”,2”-tetrakis(p-dimethylaminophenyl)ethenyl] -2,2-Diacetylethane;Bis[2,2,2',2'-tetrakis(p-dimethylacetone] [aminophenyl]ethenyl-methylmalonic acid dimethyl ester, and the like.

[0030] [Other color developers] The thermosensitive recording layer may contain a developer other than that represented by formula (1) within a range that does not impair the effects of the present invention. As other color developers, any of those known in the field of conventional pressure-sensitive or heat-sensitive recording paper may be used. Any of the above-mentioned color developers can be used, and although there is no particular limitation, the color developer is preferably an electron-accepting color developer. The other color developers may be used alone or in combination of two or more. When the developer is used, the amount of the developer is preferably Or, 1 to 5000 parts by weight, more preferably, 5 to 1000 parts by weight, and further preferably , 10 to 500 parts by weight. By using other color developers, high color sensitivity is maintained while heat resistance and moisture resistance are improved. Thus, it is possible to obtain an excellent heat-sensitive recording material having improved image preservation properties such as colorfastness and water resistance. As for other developers, any developer known in the field of conventional pressure-sensitive or heat-sensitive recording paper can be used. Other color developers include bisphenol compounds, urea compounds, and the like. Preferred are phenol compounds and novolak-type phenol compounds.

[0031] Bisphenol compounds include 4,4'-isopropylidenediphenol, 2,2 '-Bis(4-hydroxy-3-methylphenyl)propane, 1,1-bis(4-hydro 2,2-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxyphenyl)-4-methyl Pentane, 4,4'-dihydroxydiphenyl sulfide, di(4-hydroxy-3-methyl 2,2'-thiobis(3-tert-octylphenyl)sulfide, 2,2'-thiobis(3-tert-octylphenol) , 2,2'-thiobis(4-tert-octylphenol), 4,4'-dihydroxy Diphenyl sulfone, 2,4'-dihydroxydiphenyl sulfone, 4-hydroxy-4 '-Propoxydiphenyl sulfone, 4-hydroxy-4'-isopropoxydiphenyl Sulfone, 4-hydroxy-4'-allyloxydiphenyl sulfone, bis(3-allyl -4-hydroxyphenyl)sulfone, 4-hydroxyphenyl-4'-benzyloxy Phenyl sulfone, 3,4-dihydroxyphenyl-4'-methylphenyl sulfone, 2 ,4-bis(phenylsulfonyl)phenol, bisphenol described in Patent No. 3913820 Phenol sulfone-bridged compound, bisphenol sulfonate described in Patent No. 4004289 Examples of such compounds include aryl ether derivatives.

[0032] The urea compounds include 4,4'-bis(3-(phenoxycarbonylamino)methyl N-(p-phenylureido)diphenyl sulfone, as described in Patent No. 4601174 toluenesulfonyl)-N'-(3-p-toluenesulfonyloxyphenyl)urea, 4,4'-bis(3-tosylureido)difluoromethane as described in JP2011-105638A Phenylmethane, N-[2-(3-phenylmethyl)ethane described in JP-A-2016-165835 phenyl]benzenesulfonamide, as described in JP 2017-165091 A N-[2-(acetoxy)phenyl]-N'-phenylurea, N-[3-(acetoxy (iii)phenyl]-N'-phenylurea, N-[2-(benzoyloxy)phenyl]- N'-Phenylurea, N-[3-(benzoyloxy)phenyl]-N'-phenylurea Rare, N-(m-tolylaminocarbonyl) described in WO 2017 / 047572 -phenylalanine, N-(p-toluenesulfonyl)-phenylalanine, N-(phenyl N-(m-tolylaminocarbonyl)-valine, N-(m-tolylaminocarbonyl)-methionine, N-(m-tolylaminocarbonyl)-tyrosine, N-(m-tolylaminocarbonyl) -Phenylglycine, N-(m-tolylaminocarbonyl)-valine, N-(m-tolyl Aminocarbonyl)-cysteine-S-benzyl, N-(m-tolylaminocarbonyl) -β-alanine, N-phenylaminothiocarbonyl-glycylglycine, N-(p-tolyl N-(p-phenylsulfonylaminocarbonyl)-phenylalanine-methyl ester Toluenesulfonyl)-β-alanine, N-(p-tolylaminocarbonyl)-methionine and amino acid derivatives such as N-(phenylaminocarbonyl)-methionine. do.

[0033] As the novolak-type phenolic compound, there are mentioned the compounds described in WO 02 / 098674. Phenol-formalin condensation products and the like.

[0034] In addition to the compounds listed above, activated clay, attapulgite, colloidal silica, and silicic acid Inorganic acidic substances such as aluminum, hydroquinone monobenzyl ether, 4-hydroxybenzoic acid Benzyl benzoate, aminobenzenesulfonamide derivatives described in JP-A-8-59603 Bis(4-hydroxyphenylthioethoxy)methane, 1,5-di(4-hydroxyphenylthioethoxy)methane phenylthio)-3-oxapentane, bis(p-hydroxyphenyl)butyl acetate, Methyl bis(p-hydroxyphenyl)acetate, 1,1-bis(4-hydroxyphenyl)- 1-Phenylethane, 1,4-bis[α-methyl-α-(4'-hydroxyphenyl)ethane ethyl]benzene, 1,3-bis[α-methyl-α-(4'-hydroxyphenyl)ethyl Benzene, as described in International Publication No. 02 / 081229 and Japanese Patent Application Laid-Open No. 2002-301873 The compounds listed above, thiourea compounds such as N,N'-di-m-chlorophenylthiourea, p-chlorophenyl Benzoic acid, stearyl gallate, bis[4-(octyloxycarbonylamino)salicylic acid, Zinc licylate dihydrate, 4-[2-(p-methoxyphenoxy)ethyloxy]salicylate 4-[3-(p-tolylsulfonyl)propyloxy]salicylic acid, 5-[p-( Aromatic carboxylic acids such as 2-p-methoxyphenoxyethoxy)cumyl]salicylic acid, and The zinc, magnesium, aluminum, calcium, titanium, and malic acids of these aromatic carboxylic acids Salts with polyvalent metals such as zinc, tin, and nickel, as well as antipyri- complexes, and complex zinc salts of terephthalaldehyde acid and other aromatic carboxylic acids. The higher fatty acid metal double salt and polyhydroxy aromatic compound described in JP-A-10-258577 are and metal chelate complexes of aromatic compounds.

[0035] Among the other developers mentioned above, 4,4'-dihydroxydiphenylsulfone, 2,4' -Dihydroxydiphenyl sulfone, 4-hydroxy-4'-propoxydiphenyl sulfone 4-Hydroxy-4'-isopropoxydiphenylsulfone, 4-Hydroxy-4 '-Allyloxydiphenyl sulfone, bis(3-allyl-4-hydroxyphenyl)sulfone Sulfon, 4,4'-isopropylidenediphenol, 2,2'-bis(4-hydroxy- 3-methylphenyl)propane, diphenylsulfone bridge described in Patent No. 3913820 Bridged compounds, diphenylsulfone derivatives described in Patent No. 4004289, and International Publication No. Phenol-formaldehyde condensates described in JP 2 / 098674, 4,4'-bis(3-(phenol (phenyloxycarbonylamino)methylphenylureido)diphenylsulfone, Patent No. 46 N-(p-toluenesulfonyl)-N'-(3-p-toluenesulfonyl)- phenyloxyphenyl)urea, 4,4'- Bis(3-tosylureido)diphenylmethane, as described in JP 2016-165835 A N-[2-(3-phenylureido)phenyl]benzenesulfonamide, International Publication N-(m-tolylaminocarbonyl)-phenylalanine as described in 2017 / 047572 N-(m-tolylaminocarbonyl)-methionine is preferred, and 4,4'-dihydro- 2,4'-dihydroxydiphenyl sulfone, 4-hydroxydiphenyl sulfone 4-Hydroxy-4'-isopropoxydiphenyl sulfone, 4-Hydroxy-4'-isopropoxydiphenyl sulfone phenyl sulfone, 4-hydroxy-4'-allyloxydiphenyl sulfone, bis(3- (allyl-4-hydroxyphenyl) sulfone, bisphenol A described in Patent No. 3913820 Nol sulfone bridged compound, bisphenol sulfone described in Patent No. 4004289 Derivatives, N-(p-toluenesulfonyl)-N'-(3 -p-toluenesulfonyloxyphenyl)urea, JP 2011-105638 A 4,4'-bis(3-tosylureido)diphenylmethane described in JP 2016-16 N-[2-(3-phenylureido)phenyl]benzenesulfonate as described in Patent Publication No. 5835 By using these, the color development sensitivity of the thermal recording material can be maintained. While improving image preservation properties (heat resistance, plasticizer resistance, moisture resistance, water resistance, grease resistance, etc.), It is possible to do so.

[0036] [Sensitizer] In this embodiment, a known sensitizer may be used. The sensitizer is not particularly limited, but examples thereof include For example, 1,2-di-(3-methylphenoxy)ethane, 2-benzyloxynaphthalene, Fatty acid amides having 10 to 21 carbon atoms (e.g., stearic acid amide, palmitic acid amide, etc.) ), ethylene bisamide, p-toluenesulfonamide, montanic acid wax, polyethylene Renwax, p-benzylbiphenyl, diphenyl sulfone, 4-biphenyl-p-tolyl aryl ether, m-terphenyl, 1,2-diphenoxyethane, dibenzyl oxalate, Di(p-chlorobenzyl) oxalate, di(p-methylbenzyl) oxalate, di(p-methylbenzyl) oxalate -p-Methylbenzyl ester, dibenzyl terephthalate, p-benzyloxybenzoic acid Benzyl, di-p-tolyl carbonate, phenyl-α-naphthyl carbonate, 1,4 -Diethoxynaphthalene, 1-hydroxy-2-naphthoic acid phenyl ester, o-hydroxy 4-(m-methylphenoxymethyl)biphenyl, 4,4'-Ethylenedioxy-bis-benzoic acid dibenzyl ester, dibenzoyloxy Methane, 1,2-di(3-methylphenoxy)ethylene, bis[2-(4-methoxy- phenyloxyethyl] ether, methyl p-nitrobenzoate, phenyl p-toluenesulfonate Among these, 1,2-di-(3-methylphenoxy) ethane, 1,2-diphenoxyethane, fatty acid amides having 10 to 21 carbon atoms (e.g., s Theramide, palmitamide, etc.), 2-benzyloxynaphthalene, diphenyl sulfone, p-toluenesulfonamide and oxalic acid-di-p-methylbenzyl ester The preferred is 1,2-di(3-methylphenoxy) which shows high color development sensitivity even at low energy. These sensitizers may be used alone or in combination of two or more. When a sensitizer is used, the amount of the sensitizer is the same as that of the developer according to the embodiment of the present invention. The amount is preferably 25 to 250 parts by weight, more preferably 50 to 100 parts by weight. 50 parts by weight.

[0037] [Stabilizer] In this embodiment, a known stabilizer may be used. The stabilizer is not particularly limited, but examples thereof include For example, hindered phenol compounds, ultraviolet absorbers (e.g., benzophenone compounds Among these, hindered phenyl compounds are preferred. The nol compound improves the image preservation properties (heat resistance, moisture resistance, water resistance, plasticizer resistance, etc.) of the recorded area. This is preferable in that it increases the The hindered phenol compound usually has 1 or more and 15 or less in one molecule, preferably is a compound having 2 to 6 hydroxyphenyl groups. The molecular weight of the amine compound is usually 200 or more and 2000 or less, preferably 250 or more and 18 00 or less, more preferably 300 or more and 1500 or less. The melting point of the mixture is preferably 100°C or higher and 300°C or lower. Furthermore, at least one of the hydroxyphenyl groups contained in the hindered phenol compound In one molecule, the position of the phenolic hydroxyl group is the 1st position, and the position is either the 2nd or 6th position. Carbon atoms bonded to hydrogen atoms (i.e., no substituents at the 2nd or 6th positions) ) is preferred.

[0038] Specific examples of the hindered phenol compounds include those described in JP-B-39-4469 and Tris(hydroxyphenyl)alkanes as described in Japanese Patent Application Laid-Open No. 56-40629; 1,1,3-tris-substituted butane compounds. These are used in combination with two or more It may also be used. The hindered phenol compounds may be used alone or in combination of two or more. When a hindered phenol compound is used in a heat-sensitive recording material, the content The amount is preferably 1 to 100 parts by weight, more preferably 1 to 100 parts by weight, based on 100 parts by weight of the color developer of the formula (1). The content is preferably 1 to 70 parts by weight, and more preferably 1 to 50 parts by weight. If the content of the compound is less than the above range, the moisture resistance, water resistance, and heat resistance of the recorded area will decrease. In addition, there is a possibility that the coloring of the blank areas due to heating cannot be suppressed. If the amount is greater than the range, the color development sensitivity may decrease and the plasticizer resistance of the recorded area may decrease. .

[0039] 〔binder〕 It is preferable to use a binder to form the heat-sensitive recording layer. Examples of the saponified polyvinyl alcohol include fully saponified polyvinyl alcohol, partially saponified polyvinyl alcohol, and saponified polyvinyl alcohol. cetoacetylated polyvinyl alcohol, carboxy-modified polyvinyl alcohol, amide-modified Polyvinyl alcohol, sulfonic acid modified polyvinyl alcohol, butyral modified polyvinyl Polyvinyl alcohol, olefin modified polyvinyl alcohol, nitrile modified polyvinyl alcohol Pyrrolidone-modified polyvinyl alcohol, silicone-modified polyvinyl alcohol, Other modified polyvinyl alcohol, hydroxyethyl cellulose, methyl cellulose, etc. cellulose, carboxymethylcellulose, polystyrene, styrene-maleic anhydride Acid copolymers, styrene copolymers such as styrene-butadiene copolymers, ethyl cellulose and cellulose derivatives such as acetyl cellulose, casein, gum arabic, oxidized starch, acetone Terephthalated starch, dialdehyde starch, esterified starch, polyvinyl chloride, polyvinyl acetate, poly acrylamide, polyacrylic ester, polyvinyl butyral, polyamide resin, Examples of the resin include silicone resins, petroleum resins, terpene resins, ketone resins, and coumarone resins. The amount of binder used is suitably about 5 to 25% by weight based on the solid content of the heat-sensitive recording layer. The binder is generally used as a solution, emulsion, dispersion, paste, or combination thereof. The solvent for the solution, emulsion or dispersion, or the medium for the paste, may be, for example, water. , alcohols, ketones, esters, hydrocarbons, etc.

[0040] [Crosslinking Agent] Examples of crosslinking agents include glyoxal, methylol melamine, and melamine formaldehyde. aldehyde resin, melamine urea resin, polyamine epichlorohydrin resin, polyamide epichlorohydrin resin Rorohydrin resin, potassium persulfate, ammonium persulfate, sodium persulfate, ferric chloride, Examples of suitable cation exchange agents include magnesium chloride, borax, boric acid, alum, and ammonium chloride. When a crosslinking agent is used, the amount of the crosslinking agent is preferably 100 parts by weight of the color developer of the formula (1). is 0.5 to 500 parts by weight.

[0041] [Pigments] Examples of pigments include silica (excluding colloidal silica), calcium carbonate, and kaolin. Inorganic materials such as carbide, calcined kaolin, diatomaceous earth, talc, titanium oxide, and aluminum hydroxide When a pigment is used, the amount of the pigment is 100% by weight of the developer of the formula (1). The amount is preferably 25 to 1000 parts by weight.

[0042] [Lubricant] Examples of the lubricant include fatty acid metal salts such as zinc stearate and calcium stearate. , waxes, silicone resins, etc. When a lubricant is used, the amount of the lubricant used is, The amount is preferably 0.5 to 500 parts by weight based on 100 parts by weight of the color developer of the formula (1).

[0043] [Other additives] Examples of other additives include dispersants, defoamers, fluorescent dyes, etc. When the additive is used, the amount of the additive is preferably Or, it is 0.5 to 500 parts by weight.

[0044] [Support] There are no particular restrictions on the shape, structure, size, material, etc. of the support used in the thermal recording material. The shape of the support may be a sheet, a roll, or the like. The support may be in the form of a single layer or a multilayer structure. The size of the support can be appropriately selected depending on the intended use of the thermal recording material. The material of the support may be, for example, a plastic film, synthetic paper, wood-free paper, or recycled paper pulp. paper, recycled paper, one-sided glossy paper, greaseproof paper, coated paper, art paper, cast coated paper, lightly coated paper, resin Laminated paper, release paper, etc. are also used. It may be used as such. The thickness of the support is not particularly limited and can be appropriately selected depending on the purpose. The thickness is preferably up to 2,000 μm, and more preferably 50 to 1,000 μm.

[0045] [Protective layer] In the heat-sensitive recording material, a protective layer may be provided on the heat-sensitive recording layer. When a protective layer is provided on the thermal recording material to improve the image preservability, the color development sensitivity decreases. However, since the color developer used in the thermal recording material has good color development sensitivity, Even if a protective layer is provided on the thermal paper, the color development sensitivity required for thermal paper can be maintained. The types and amounts of various components used in the method are determined according to the required performance and recording properties. However, the present invention is not limited to the above.

[0046] [Underlayer, back layer, middle layer] In thermal recording materials, the main components are pigments and binders, with the aim of further increasing color development sensitivity. An underlayer composed of the above may be provided between the support and the heat-sensitive recording layer. In order to correct the curl of the recording material, a sheet is attached to the side of the support opposite to the side on which the thermal recording layer is present. As an embodiment of each layer in the heat-sensitive recording material of the present invention, a protective layer may be provided. Examples of the laminate include a laminate having a thermal recording layer, an underlayer, a support and a back layer in this order. Not limited to: Further, between the support and the underlayer, between the underlayer and the thermal recording layer, An intermediate layer is formed between the recording layer and the protective layer and / or between the support and the back layer. Good too.

[0047] [Method of manufacturing thermal recording material] The thermal recording material is a basic leuco dye, a developer, a sensitizer, and other materials as required. A coating solution containing the sensitizer, other color developers, stabilizers, etc. is applied to at least one side of the support. The thermal recording layer can be formed by coating or drying at least a part of the substrate. This coating liquid can be applied according to a well-known conventional technique. There is no particular limitation on the coating means. For example, air knife coater, rod blade coater, bent blade coater Equipped with various coaters such as bevel blade coater, roll coater, curtain coater, etc. Any off-machine or on-machine coater may be used.

[0048] The coating liquid for forming the thermal recording layer contains, for example, a color developer and a sensitizer, and optionally Leuco dyes, other sensitizers, other color developers, stabilizers, etc. are mixed and then mixed in a ball mill or atlantic. Grinding machines such as iterators and sand grinders, or suitable emulsifying equipment, to produce particles of several microns or less. After the particles are pulverized to a diameter of about 100 mm, a binder or the like can be added to form the powder. The solvent used in the coating liquid may be water, alcohol, or the like. The solid content of the coating liquid is It is usually 20 to 40% by weight. The coating amount of the thermal recording layer can be appropriately selected depending on the composition and the application of the thermal recording material. However, the dry weight is usually 1 to 20 g / m 2 , preferably 2 to 12 g / m 2 is in the range .

[0049] In addition, the protective layer, underlayer, back layer, and intermediate layer can also be formed by applying and drying a coating solution containing the same constituent components as the heat-sensitive recording layer described above. Furthermore, a known treatment in this field (for example, a smoothing treatment by supercalendering or the like) may be applied to the heat-sensitive recording material on which each layer is formed.

[0050] [Uses of the Heat-Sensitive Recording Material] The heat-sensitive recording material of this embodiment can be suitably used for applications such as paper, film, IC cards, friction ball pens, etc.

Examples

[0051] Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to the following examples as long as it does not exceed the gist thereof. In the following examples and comparative examples, paper provided with an underlayer on one side of the support was used, and a heat-sensitive recording layer (heat-sensitive coloring layer) was formed on the underlayer. In the following examples and comparative examples, "parts" and "%", unless otherwise specified, indicate "parts by weight" and "weight %", respectively.

[0052] [Coating Solution for the Heat-Sensitive Recording Layer] The following Liquid A to Liquid F were each prepared. In Liquid A, Liquid B, and Liquid C, wet grinding was performed with a Ready Mill (RMB-02 ) manufactured by Imex until the average particle diameter of each component reached 0.5 μm. Here, the average particle diameter is the average diameter in the volume-based distribution, and was measured with a laser diffraction / scattering type particle size distribution measuring device (Microtrac MT3000 II) manufactured by Nikkiso Co., Ltd.

[0053] [Example 1] [Liquid A] ​​​​​​· 4-Methyl-N-[[[3-(trifluoromethyl)phenyl]amino]carbonyl] benzenesulfonamide (synthesis example in Patent Document 1 (International Publication No. 2021 / 107037)) Based on Example 2, it was synthesized by the same operation. Hereinafter, it is referred to as "Compound 1". : 28.0 parts · Kraft lignin (derived from softwood): 12.0 parts · Polyvinyl alcohol (10% aqueous solution): 50.0 parts · Water: 10.0 parts <Liquid B> · 3-Dibutylamino-6-methyl-7-anilinofluoran (manufactured by Yamamoto Chemical Co., Ltd., trade name "ODB-2"): 36.5 parts · Polyvinyl alcohol (10% aqueous solution): 60.0 parts · Water: 3.5 parts <Liquid C> · Stearamide (manufactured by Mitsubishi Chemical Corporation, trade name "AP-1") : 40.0 parts · Polyvinyl alcohol (10% aqueous solution): 50.0 parts · Water: 10.0 parts <Liquid D> · 60% calcium carbonate dispersion (manufactured by Okutama Kogyo Co., Ltd., trade name "Tamapal TP- 123CS") <Liquid E> · 36% zinc stearate dispersion (manufactured by Chukyo Yushi Co., Ltd., trade name "Hydrin Z-8-36" ) <Liquid F> · 10% polyvinyl alcohol aqueous solution (manufactured by Nippon Gosei Co., Ltd., trade name "Gosenol NH-1 8" of 10% aqueous solution)

[0054] Each liquid was mixed in the following ratio to prepare a coating liquid for the heat-sensitive recording layer. Liquid A: 18.89 parts Liquid B: 10.00 parts Liquid C: 9.44 parts Liquid D: 17.87 parts Liquid E: 6.00 parts Liquid F: 19.62 parts Next, an underlayer was provided on one side of the high-quality paper serving as the support, and on top of the underlayer, a heat-sensitive recording layer with a dry weight of 3 g / m 2 was formed by applying and drying (using a forced-air dryer at 60°C for 2 minutes) the coating liquid for the heat-sensitive recording layer. Subsequently, the support on which the underlayer and the heat-sensitive recording layer were formed was processed with a supercalender so that the smoothness became 500 - 1000 seconds to obtain a heat-sensitive recording material. This was smoothed by applying a pressure of 1 kgf / cm with a supercalender 2 to obtain a heat-sensitive recording material.

[0055] [Example 2] The following proportions of each liquid were mixed to prepare a coating liquid for the heat-sensitive recording layer. Liquid A: 18.89 parts Liquid B: 10.00 parts Liquid D: 17.87 parts Liquid E: 6.00 parts Liquid F: 19.62 parts Next, an underlayer was provided on one side of the high-quality paper serving as the support, and on top of the underlayer, a heat-sensitive recording layer with a dry weight of 3 g / m 2 was formed by applying and drying (using a forced-air dryer at 60°C for 2 minutes) the coating liquid for the heat-sensitive recording layer. Subsequently, the support on which the underlayer and the heat-sensitive recording layer were formed was processed with a supercalender so that the smoothness became 500 - 1000 seconds to obtain a heat-sensitive recording material. This was smoothed by applying a pressure of 1 kgf / cm with a supercalender 2 to obtain a heat-sensitive recording material.

[0056] [Example 3] The proportion of Liquid A was <Liquid A> · Compound 1: 20.0 parts · Kraft lignin (derived from softwood): 20.0 parts · Polyvinyl alcohol (10% aqueous solution): 50.0 parts · Water: 10.0 parts A heat-sensitive recording material was produced in the same manner as in Example 2, except that it was changed to the above.

[0057] [Example 4] A heat-sensitive recording material was produced in the same manner as in Example 2, except that kraft lignin (derived from softwood) in the liquid A was changed to enzymatically decomposed lignin (derived from corn cobs). A heat-sensitive recording material was produced in the same manner as in Example 2, except that kraft lignin (derived from softwood) in the liquid A was changed to enzymatically decomposed lignin (derived from corn cobs).

[0058] [Comparative Example 1] The proportion of liquid A was <Liquid A> · Compound 1: 40.0 parts · Polyvinyl alcohol (10% aqueous solution): 50.0 parts · Water: 10.0 parts A heat-sensitive recording material was produced in the same manner as in Example 1, except that it was changed to the above.

[0059] [Comparative Example 2] The proportion of liquid A was <Liquid A> · Compound 1: 40.0 parts · Polyvinyl alcohol (10% aqueous solution): 50.0 parts · Water: 10.0 parts A heat-sensitive recording material was produced in the same manner as in Example 2, except that it was changed to the above.

[0060] <Color development sensitivity test> Using a thermal printer (TH-M2 / PS) manufactured by Okura Electric Co., Ltd., printing of a tone pattern was performed, and the image density at an applied energy of 0.36 mJ / dot was measured with a spectrophotometric density · colorimeter (eXact) manufactured by X-Rite. The results are shown in Table 1. In this test, the image density indicates that the higher the value, the better the color development sensitivity.

[0061] <Alcohol resistance> An Okura Electric thermal printer (TH-M2 / PS) was used to apply an energy of 0.3 Thermal recording material printed with a checkered pattern at 6 mJ / dot was immersed in 25% ethanol water for 20 minutes. After leaving it at room temperature for 24 hours, the image density was measured using an X-Rite spectrodensitometer. The image retention rate after the test is shown in Table 1.

[0062] [Table 1] As is clear from the results in Table 1, Example 1 has a higher alcohol resistance than Comparative Example 1. The high image density was maintained even after the test.

[0063] [Table 2] In addition, as is clear from the results in Table 2, in Examples 2 to 4, the image quality of the printed portion is improved compared to Comparative Example 2. The image density has increased and the color sensitivity has improved. In addition, the image shows high alcohol resistance even after the test. The concentration was maintained. From the above, it was found that the developer described in the present application and the isolated lignin as an additive were It can be seen that the use of , provides excellent alcohol resistance in durability tests.

[0064] As described above, the present invention provides a heat-sensitive recording material having excellent alcohol resistance. can.

Claims

1. A heat-sensitive recording material comprising a developer represented by the following formula (1) and isolated lignin: 【Chemistry 1】 (In the above formula (1), a, A, and L are as follows: a is an integer selected from 1 to 5; Each A is independently a fluoro group or a perfluoroalkyl group; L is any functional group represented by the following formula (2). 【Chemistry 2】 In the above formula (2), R is an alkyl group having 1 to 4 carbon atoms. ＊ is a bond with the sulfur atom in formula (1) The binding site is shown.)

2. The color developer according to claim 1 , wherein a is 1 or 2 in the formula (1).

3. The color developer according to claim 1 or 2, wherein in the formula (1), A is substituted at the m-position or p-position. 。

4. The color developer according to claim 3, wherein in the formula (1), A is substituted at the m-position.

5. The color developer according to claim 3 or 4, wherein a is 1 in the formula (1).

6. Any one of claims 1 to 5, wherein in the formula (1), A is a fluoro group or a trifluoromethyl group.

10. The developer according to claim 1 .

7. In the formula (1), L is a phenyl group, an o-toluyl group, an m-toluyl group, or a p-toluyl group. The colour developer according to any one of claims 1 to 6, which is selected from the group consisting of

8. 8. The method according to claim 1, wherein the isolated lignin is a kraft lignin or an enzymatically decomposed lignin. The developer according to any one of claims 1 to 5.

9. The heat-sensitive recording material according to any one of claims 1 to 8, wherein the heat-sensitive recording layer contains a sensitizer.

10. The weight ratio of the developer to the isolated lignin (developer / isolated lignin) is 40 / 60 to 90 / 1 10. The heat-sensitive recording material according to claim 1, wherein the molecular weight is 0.

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