JPH04257490A - Heat-sensitive recording sensitizer and material - Google Patents

Abstract

PURPOSE:To obtain heat-sensitive recording material which is outstandingly high in coloring sensitivity and whose lowering in whiteness, light-proofness and plasticizer resistance is avoided, particularly in a battery containing a lubricant, by incorporating at least electron-donating colorless color former, electro-accepting color developing substance and a specific sensitizer in the layers formed on a supporting body. CONSTITUTION:For production of a recording material is selected a heat-sensitive recording sensitizer consisting of the aromatic nitro compound having a solubility parameter of 9.5-13 and represented by the formula I wherein Y is alkylene group having 1-4 carbon atoms or alkenylene group having 2-4 carbon atoms, X and Z are O atom, S atom, -COO-, -COS or -OCO-, Ar1 and Ar2 are phenyl group which may have substituent and a is an integer of 1-4 and fatty acid amides. A lower layer 3 consisting of a mixture of the aforesaid sensitizer and a color former and an upper layer 4 consisting of a mixture of this sensitizer and a color developer are coated together on a supporting body 1, thereby obtaining a heat-sensitive recording material. By adding a lubricant to the recording material, the lowering thereof in coloring sensitivity, whiteness, light proofness, moisture resistance and plasticizer resistance is avoided.

Description

Description: FIELD OF INDUSTRIAL APPLICATION This invention relates to a sensitizer for heat-sensitive recording and a material for heat-sensitive recording. More specifically, the present invention relates to a sensitizer for heat-sensitive recording paper and a heat-sensitive recording material such as heat-sensitive recording paper. [0002] In recent years, there has been a significant demand for faster information processing, and various high-speed devices have been developed. Along with this, there is a demand for highly sensitive heat-sensitive recording materials. Heat-sensitive recording materials such as heat-sensitive recording paper develop color by melting an electron-donating colorless coloring agent and an electron-accepting color-developing substance contained in a layer formed on a support such as paper with heat and causing the two to associate. It is made using the principle of As sensitizers used in combination with the above-mentioned color forming agents and color developing substances to improve sensitivity, for example, sensitizers such as benzyl biphenyls (Japanese Unexamined Patent Publication No. 60-82382), 1, Sensitizers such as 2-bis(phenoxy)ethane (Japanese Unexamined Patent Publication No. 60-56588) have been proposed. [0004] Problems to be Solved by the Invention [0004] However, the color development sensitivity of heat-sensitive recording materials using these sensitizers is still insufficient, and in particular, high-grade materials such as zinc stearate and calcium stearate are used to prevent sticking. When a lubricant such as a fatty acid metal salt is added, there is a problem in that the color development sensitivity decreases. Further, there is a problem in that side effects due to increased sensitivity, ie, decreases in whiteness, light resistance, moisture resistance, and plasticizer resistance, cannot be avoided. [Means for Solving the Problems] The present inventors have conducted intensive studies to solve these problems, and as a result, have arrived at the present invention. That is, the present invention has a solubility parameter of 9.5 to 1.
3, with the general formula Ar1X(Y)aZAr2-NO2 (1) [wherein, Y is an alkylene group having 1 to 4 carbon atoms or 2 to
4 alkenylene group; X and Z are O atom, S atom, -CO
O-, -COS- or -OCO-; Ar1 and Ar2 are phenyl groups which may have substituents; a represents an integer from 1 to 4]; and a fatty acid. A sensitizer for heat-sensitive recording characterized by comprising an amide (B); and at least an electron-donating colorless color former, an electron-accepting color developer, and the above-mentioned sensitizer in a layer formed on the support. This is a heat-sensitive recording material characterized in that it contains an agent and that this layer develops color under heat. In the present invention, the solubility parameter (hereinafter S
Cohesive energy density (abbreviated as P)
Energy Density (hereinafter abbreviated as CED)
] indicates the square root of Also, as shown in the formula below, CED indicates the amount of energy required to evaporate 1 cm3 of a substance physically and chemically. (SP)2=CED=△E/V=(△H-RT)/V△
E=evaporation energy (cal/mol) V=
Molar capacity (cm3/mol) △H=latent heat of vaporization (cal/
mole) R = gas constant (1
．． 987 cal/mol゜k) T = absolute temperature
(°k) SP indicates the degree of polarity of the molecule. That is, the value of SP governs the thermodynamic properties of a solution, and from this value, solubility and the like can be quantitatively predicted or explained. The method for calculating SP is described in "Polymer Engineering and Science" by Robert F. Feders, February 1974, Volume 14, No. 2 or "Solution and Solubility" by Kozo Shinoda, published by Maruzen Co., Ltd., pages 92 to 106. In the present invention, the group representing Y has 1 carbon number
Examples of the alkylene groups of -4 include alkylene groups such as methylene, ethylene, propylene, and butylene groups (these groups may be linear or branched). Among the groups representing Y, examples of alkenylene groups having 2 to 4 carbon atoms include vinylene (ethynylene) and propenylene groups. Among these groups representing Y, preferred are methylene,
Ethylene and propylene groups, especially methylene and ethylene groups. [0009] a is an integer from 1 to 4; Preferably it is 1. [0010] X and Z are O atom, S atom, -COO-,
-COS- or -OCO-, preferably an O atom or -OCO-. Further, X and Y may be the same or different. Specific examples of substituents in the phenyl group which may have substituents represented by Ar1 and Ar2 include alkyl groups having 1 to 22 carbon atoms [methyl, ethyl, n-propyl, n-butyl, tert Butyl, hexyl, octyl, nonyl, decyl, etc.], alkenyl group [isopropenyl, allyl group, etc.], aralkyl group [benzyl, phenethyl group, etc.], aryl group [phenyl, tolyl, xylyl, biphenyl, naphthyl, cumyl groups], cycloalkyl groups [cyclohexyl groups, etc.], alkoxy groups [methoxy, ethoxy groups, etc.], aryloxy groups [phenoxy groups, etc.], alkylthio groups [methylthio, ethylthio groups, etc.], arylthio groups [phenylthio groups, etc.] ], alkoxycarbonyl group [methoxycarbonyl,
ethoxycarbonyl group, tert-butoxycarbonyl group, etc.], aryloxycarbonyl group [phenoxycarbonyl group, etc.], acyl group [acetyl, propionyl group, etc.]
butyryl, isobutyryl, etc.], aryloyl groups (benzoyl, etc.), halogen groups (chloro, bromo, etc.), cyano groups, nitro groups, etc. There may be two or more of these substituents. Among the groups represented by Ar, preferred are phenyl, alkylphenyl, and alkoxyphenyl groups. Specific examples of the aromatic nitro compound (A) and their solubility parameters (SP) are shown in Tables 1 to 3 below. [Table 1] [Table 2] [Table 2] [Table 3] [0015] Among the aromatic nitro compounds (A) exemplified above, preferred ones are ethylene glycol mono (nitro-substituted) in Table 1. ) phenyl ethers and (nitro-substituted)
Ethers with phenols, in Table 2 (nitro substitution)
Esters of phenoxyalkyl carboxylic acids and (nitro-substituted) phenols, and esters of ethylene glycol mono (nitro-substituted) phenyl ethers and (nitro-substituted) phenyl carboxylic acids in Table 3, especially ethylene glycol mono (nitro-substituted) These are esters of phenyl ethers and (nitro-substituted) phenylcarboxylic acids, and more preferred are esters of ethylene glycol monophenyl ether and (nitro)phenylcarboxylic acids. Two or more different aromatic nitro compounds (A) may be used in combination. Aromatic nitro compound (A) in the present invention
can be produced by any known method; for example, the compounds shown in Table 1 can be obtained by etherifying dihalogenated alkylene and nitrophenol using an alkaline catalyst such as caustic potash. The compounds shown in Table 2 can be obtained by esterifying (nitro)phenoxycarboxylic acid chloride and (nitro)phenol in the presence of a tertiary amine, pyridine, or the like. The compounds in Table 3 are produced by adding alkylene oxide to phenols using an alkaline catalyst such as caustic soda, caustic potash, sodium metal, or methylate, and then adding nitrobenzoic acid in the presence of an acidic catalyst such as sulfuric acid, p-toluenesulfonic acid, or phosphoric acid. It can be obtained by carrying out an esterification reaction. In the present invention, fatty acid amides (B) include compounds having at least one fatty acid amide group in one molecule, specifically, compounds represented by the following general formula (2). General formula R1CONHR2
(2)
[In the formula, R1 is a hydrocarbon group having 1 to 22 carbon atoms, R2 is hydrogen, a hydrocarbon group having 1 to 22 carbon atoms, -
C2H4NHCOR3 group, -CONH group, -CSNH2
represents a phenyl group which may have a substituent or a naphthyl group which may have a substituent] In the general formula (2), R1 and R2 are hydrocarbon groups having 1 to 22 carbon atoms; Specific examples include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, Straight chain or branched alkyl groups such as heptadecyl, octadecyl, nonadecyl, eicosyl, heneicosyl, docosyl, and octacosyl can be mentioned. Specific examples of each substituent of the phenyl group which may have a substituent and the naphthyl group which may have a substituent for R2 include the substituents exemplified as substituents in the Ar1 and Ar2 groups. etc. can be given. 0020
] Specific examples of the aliphatic amides (B) are shown in Tables 4 to 15 below. [Table 4] [Table 5] [Table 5] [Table 6] [Table 7] [Table 8] [Table 8] [Table 9] [Table 10] [Table 11] [Table 12] [Table 12] [Table 13] [Table 14] [Table 15] [0033] Preferred among the aliphatic amides (B) exemplified above The compounds listed in Table 4, Table 5, Table 6, Table 7, Table 8, and Table 9 are particularly preferred, and particularly preferred are stearic acid amide, behenic acid amide, stearic acid dodecylamide, N,N'- Methylenebislauric acid amide, N,N'-methylenebisstearic acid amide, N,N
'-ethylenebislauric acid amide, N,N'-methylenebisstearic acid amide, stearic acid monoureide, palmitic acid anilide, stearic acid anilide and stearic acid p-toluidide. Two or more different types of aliphatic amides (B) may be used in combination. [0034] Each compound has an SP, and for electron-donating colorless coloring agents used in thermosensitive recording materials, for example, 2-anilino-3-methyl-6
-N-ethyl-N-isoamylaminofluorane is 11
．． 50; 2-anilino-3-methyl-6 diethylaminofluorane is 11.94; 2-anilino-3-methyl-
6-dibutylaminofluorane is 11.44, and regarding electron-accepting color developing substances, for example, bisphenol A is 11.44.
3.64; Bisphenol S is 18.94; salicylic acid benzyl ester is 12.69; regarding lubricants, for example, zinc stearate is 9.16; aluminum stearate is 9.71; lead stearate is 9.22; Cadmium stearate is 9.20. As mentioned above, the SPs of the electron-donating colorless coloring agent, the electron-accepting color-developing substance, and the lubricant are quite different from each other, and it can be seen that they are difficult to respond to instantaneous dissolution by heat. The role of the sensitizer (solid solvent) is to easily dissolve even these compounds with far apart SP, and the shorter the dissolution time in hot dissolution, the better the sensitizer. [0036] In order to produce a heat-sensitive recording paper with excellent sensitivity, it is necessary to select and combine drugs with excellent solubility. Electron-donating colorless coloring agent, electron-accepting color-developing substance,
It is preferable to select a lubricant whose SP is similar to that of each drug, and to use a sensitizer located between the SPs of each drug. The sensitizer has an SP of 9.5 to 13.
The aromatic nitro compound (A) and the fatty acid amide (B) are used in combination, and very good sensitivity can be obtained. In the sensitizer of the present invention, (A) and (B)
The weight ratio is usually 25:75 to 80:20, preferably 3
0:70-75:25, particularly preferably 35:65-7
It was 0:30. When (A) is less than 25 or more than 80, the sensitivity for thermal recording paper tends to decrease. Further, when (B) is less than 20, the sensitivity becomes low, and when (B) exceeds 80, the static coloring temperature tends to decrease. [0038] To illustrate the method for producing the sensitizer of the present invention,
(1) A method of pulverizing each component and mixing it, (2) (A)
, (B) A method of melting each with heat, mixing them, and turning them into fine powder after cooling. (3) A method of uniformly dissolving (A) and (B) in a solvent, making a mixed solution, and then removing the solvent or dissolving the mixed solution. Examples include a method in which the powder is poured into a large amount of solvent to cause coprecipitation to form a fine powder, but method (1) is preferred. Solvents used in method (3) include alcohols (methanol, ethanol, isopropanol, etc.), ketones (acetone, methyl ethyl ketone, cyclohexanone, etc.), amides (N,N'- dimethylformamide, N,N'-dimethylacetamide), sulfoxides (dimethylsulfoxide, etc.), ethers (tetrahydrofuran, dioxane, ethylene glycol)
(monomethyl ether, etc.), esters (methyl acetate, ethyl acetate, butyl acetate, etc.), fatty acid halogenated hydrocarbons (chloroform, methylene chloride, dichloroethylene, carbon tetrachloride, trichloroethylene, etc.), aromatic hydrocarbons (benzene, toluene, xylene, etc.), aliphatic hydrocarbons (ligroin, etc.), aromatic halogenated hydrocarbons (monochlorobenzene, dichlorobenzene, etc.), and mixed solvents of two or more of these can be used. In the heat-sensitive recording material of the present invention, the electron-donating colorless coloring agent (hereinafter abbreviated as coloring agent) is not particularly limited, and examples thereof include those used in known heat-sensitive or pressure-sensitive recording materials. It will be done. Examples of the known coloring agents include triarylmethane-based, diphenylmethane-based, xanthene-based, phenothiazine-based, and spiropyran-based coloring agents described in Japanese Patent Application No. 2-303176. Two or more of these coloring agents may be used in combination. 004
1] On the other hand, as the electron-accepting color-developing substance (hereinafter abbreviated as color-developing agent), various electron-accepting color-developing substances can be used that react with the color former when heated to develop color. . Examples of such color developers include phenolic substances, organic or inorganic acidic substances, and salts thereof. Specific examples include, for example, “Paper and Pulp Technology Times, Tech Time Co., Ltd., Vol. 30 No. 6 to Vol. 31 No. 3.
"Color developer for thermal recording paper (1)" serialized in "No."
(Complete), Written by Takashi Shiga” and “The same magazine, Vol. 32, No. 4 – Vol. 32, Vol. 1
Examples include those described in "Color Developers for Thermal Recording Paper (1) to (Complete), Written by Takashi Shiga" of "No. 0". Specific examples include bisphenol color developers, hydroxyarylcarboxylic acid color developers, and sulfone color developers described in Japanese Patent Application No. 2-303176. Two or more of these color developers may be used in combination. In the heat-sensitive recording material of the present invention, the amount of the sensitizer of the present invention used is usually 1 to 200 parts by weight, preferably 3 to 100 parts by weight, particularly preferably 1 to 200 parts by weight, based on 100 parts by weight of the color developer. is 10 to 70 parts by weight. If the amount of the sensitizer used in the present invention is less than 1 part by weight, the effect of improving sensitivity in thermosensitive recording will be reduced, and if it exceeds 200 parts by weight, the effect of improving sensitivity will be saturated and uneconomical. The ratio of the color former to the color developer is usually 5 to 100 parts by weight, preferably 10 to 70 parts by weight, particularly preferably 2 parts by weight, per 100 parts by weight of the color former.
It is 0 to 50 parts by weight. If the amount of the color developer used is less than 5 parts by weight, the color density will decrease, and if it exceeds 100 parts by weight, the color density will reach an equilibrium, making it uneconomical to use any more. Next, a method for producing the heat-sensitive recording material of the present invention will be illustrated. First, a suspension solution containing each of the sensitizer, color former, and color developer of the present invention is prepared. To exemplify the method for producing each suspension solution, a sensitizer and a binder, a color former and a binder, a color developer and a binder are mixed in water, and if necessary, a surfactant (2-ethylhexyl sulfosuccinate soda salt, A suspension solution is obtained by pulverizing and dispersing the powder into particles of 10 μm or less, preferably 3 μm or less, using a pulverizer such as a ball mill, atrider, or sand grinder. [0046] As the above-mentioned binder, for example,
The binder (water-soluble polymer or latex) described in No. 303176 can be used. [0047] Subsequently, each of the suspension solutions may be used alone or a suspension solution mixture consisting of a combination according to various coating methods may be used as a coating solution and coated on a support to produce a heat-sensitive recording material. As shown in Table 16 below, the coating solution may be a mixture of three suspension solutions, a mixture of two components, or a single suspension solution, depending on the various coating methods. [0048] [0049] Further, each coating liquid may contain auxiliary additive components, such as fillers and lubricants, which are commonly used in this type of heat-sensitive recording material, if necessary. Examples of fillers include calcium carbonate,
Silica, zinc oxide, titanium oxide, aluminum hydroxide,
In addition to inorganic fine powders such as zinc hydroxide, barium sulfate, clay, kaolin, talc, surface-treated calcium carbonate and silica, organic powders such as urea/formalin resin, styrene/methacrylic acid copolymer, and polystyrene resin. Fine powder can be given. As lubricants, in addition to higher fatty acid metal salts such as zinc stearate, calcium stearate, magnesium stearate, lead stearate, cadmium stearate, barium stearate, and aluminum stearate, stearic acid, polyethylene , carnauba wax, beeswax, paraffin wax, and other waxes. The amount of the lubricant used is usually 0 to 300 parts by weight, preferably 10 to 200 parts by weight, per 100 parts by weight of the color developer. If the amount of lubricant used exceeds 300 parts by weight, thermal head residue will increase, which is undesirable. [0053] The method of applying the coating liquid to the support is as follows:
For example, apply the coating solution to the support using an air knife coater or a blade.
Coating is done using methods such as a do coater, roll coater, or wipe press. Further, as a method for forming the heat-sensitive recording layer, the heat-sensitive recording layer can be formed, for example, by the following methods <1> to <7> in which the combinations selected from coating liquids a to g shown in Table 16 are changed. . <1> Coating the coating liquid (a) onto the support. FIG. 1 shows the obtained thermosensitive recording material. In Figure 1,
1 is a support, and 2 is a layer containing a mixture of a sensitizer, a color former, and a color developer. <2> Coating liquid (d) is applied onto the support, and coating liquid (e) is further applied on top of the coating liquid (d). FIG. 2 shows the obtained thermosensitive recording material. In FIG. 2, 5 is a layer containing a mixture of a color former and a color developer, and 6 is a sensitizer layer. <3> Coating the coating liquid (e) on the support,
Furthermore, coating liquid (d) is applied to the upper layer. FIG. 3 shows the obtained thermosensitive recording material. In FIG. 3, 6 is a layer of a sensitizer, and 5 is a layer containing a mixture of a color former and a color developer. <4> Coating liquid (g) and coating liquid (
e) and coating liquid (f) are applied in a layered manner. FIG. 4 shows the obtained thermosensitive recording material. In Figure 4, 8
6 is a layer of a color developer, 6 is a layer of a sensitizer, and 7 is a layer of a color former. <5> Coating liquid (f) and coating liquid (
e) and coating solution (g) are applied in a layered manner. The obtained thermosensitive recording material is shown in FIG. In Figure 5, 6
7 is a sensitizer layer, 7 is a color former layer, and 8 is a color developer layer. <6> Coating the coating liquid (b) on the support,
Furthermore, coating liquid (c) is applied to the upper layer. The obtained thermosensitive recording material is shown in FIG. In FIG. 6, 3 is a layer in which a sensitizer and a color former are mixed, and 4 is a layer in which a sensitizer and a color developer are mixed. <7> Coating the coating liquid (c) on the support,
Furthermore, coating liquid (b) is applied to the upper layer. The obtained thermosensitive recording material is shown in FIG. In FIG. 7, 4 is a layer in which a sensitizer and a color developer are mixed, and 3 is a layer in which a sensitizer and a color former are mixed. Among these, preferred methods for forming the heat-sensitive recording layer are <2>, <6>, and <7>. The coating thickness of each layer is determined depending on the form of the heat-sensitive recording material and other conditions. The amount of coating is not particularly limited, but is usually 0.5 to 20 g in dry weight.
/m2, preferably 1 to 15 g/m2, particularly preferably 3 to 10 g/m2. [Example] The present invention will be further explained below with reference to Examples, but the present invention is not limited thereto. Parts and percentages in the examples are by weight. Further, the test methods in the examples are shown below. (Test Method) (1) Color Development 1) Dynamic Color Development Test The prepared thermosensitive recording paper was tested for the relationship between operating time (pulse width) and color density using an MSI type thermal head color development device. 0.1 to 1.0 msec, voltage 22V. The color density was determined by measuring the reflection density using a Macbeth densitometer (manufactured by Macbeth). The larger the value, the higher the color density. 2) Static color development test The prepared thermal recording paper was colored using a heat gradient heat sealer at a temperature range of 70°C to 100°C, a printing pressure of 2kg/cm, and a pressure bonding time of 2 seconds. The reflection density was measured. The concentration meter is the same as 1). (2) Whiteness (background fog) Hunter whiteness and B value before coloring of thermal recording paper are Multi Sp
electro Color Meter MSC-2
It was measured using a mold. The larger the value, the higher the degree of whiteness. (3) Light resistance Color development test The colored image area was irradiated with a xenon lamp at 30° C. for 7 hours, and the reflection density of the irradiated area was measured. The concentration meter is the same as 1). (4) Humidity Resistance Test The image area colored in the color development test was left in a constant temperature and humidity chamber at 45° C. and 90% RH for 24 hours, and then the reflection density of the image area was measured. The concentration meter is the same as 1). (5) Plasticizer Resistance Test A plastic eraser was placed on the image area that had been colored in advance in the color development test, and after being left for 24 hours, the reflection density of the image area was measured. The concentration meter is the same as 1). Production Examples 1 to 4 and Comparative Production Examples 1 to 3 Each of the compounds shown in Table 17 was finely pulverized to obtain sensitizers I to D of the present invention shown in Table 17, respectively. The sensitizers of comparative production examples were obtained by finely pulverizing each compound shown in Table 17. [Table 17] Examples 1 to 8, Comparative Examples 1 to 6 Tables 18 to 21
After pulverizing and dispersing the AA, BB (1), BB (2) and CC liquids shown in the following in a ball mill for 24 hours,
Each solution was thoroughly mixed in the combinations shown in Table 22 to create coating solutions for Examples 1 to 8. Apply this coating liquid to high-quality paper (basis weight 50g/
m2) with a doctor blade to a dry solid content of 6 g/m2, and after drying, the heat-sensitive recording materials of the present invention of Examples 1 to 8 were prepared. In addition, coating liquids and heat-sensitive recording materials of Comparative Examples 1 to 6 shown in Table 22 were created in the same manner. Tables 23 and 24 show the results of measuring each performance of the heat-sensitive recording materials of Examples 1 to 8 and Comparative Examples 1 to 6. [Table 18] [Table 19] [Table 19] [Table 20] [0076] [Table 21] [Table 22] [0078] [Table 23] [0079] [Table 24] As is clear from Tables 23 and 24, the whiteness, color development, light resistance, moisture resistance, and plasticizer resistance of the thermal recording paper of the present invention were all superior to those of conventional thermal recording paper. In particular, static color development was excellent. Examples 9 to 12 and Comparative Example 7 The DD and EE solutions shown in Tables 25 and 26 were ground and dispersed in a ball mill for 24 hours to obtain suspension solutions. Spread this solution on high-quality paper (basis weight 60)
g/m2) in the methods of <1>, <6>, and <7>, that is, <1> is a mixture of DD liquid and EE liquid (1/1 weight ratio) on paper with a dry solid content of 8 g/m2. It was applied with a doctor blade and dried. In <6>, coating liquid DD was applied to paper using a doctor blade so that the dry solid content was 4 g/m 2 , and then coating liquid EE was similarly applied onto this layer and dried. <7> was the reverse of <6>, in which the EE liquid was applied first, and then the DD liquid was applied. The coating amount was the same as in <6>. [Table 25] [Table 26] [0084] The heat-sensitive recording materials prepared by coating methods <1>, <6> and <7> were used in Examples 9, 10 and 1, respectively.
It was set as 1. In addition, as Comparative Example 7, 1 of DD and EE liquids
-(p-Nitrobenzoyloxy)-2-(4-methylphenoxy)ethane/N,N'-ethylenebisoctadecanamide (8:2) using p-benzylbiphenyl to prepare <1>. A heat-sensitive recording material (Comparative Example 7) was prepared by coating according to the coating method. Next, the performance of the heat-sensitive recording materials of Examples 9-11 and Comparative Example 7 was measured, and the results are shown in Tables 27-28. [Table 27] [Table 28] [0087] As is clear from Tables 27 and 28, the whiteness, color development, light fastness, moisture resistance, and plasticizer resistance of the heat-sensitive recording material of the present invention are higher than those of conventional materials. It was superior to other heat-sensitive recording materials. Example 10 was the best. Effects of the Invention The heat-sensitive recording material of the present invention containing the sensitizer of the present invention has extremely high color development sensitivity, and in particular, even when a lubricant is added, the color development sensitivity does not decrease as in the past. do not have. It also has excellent whiteness (background fog), and does not deteriorate even when a lubricant is added like in the past. Additionally, the image area provides high quality performance such as light fastness, moisture resistance and plasticizer resistance. That is, there is no decrease in side effects (whiteness, light resistance, moisture resistance, and plasticizer resistance) associated with increased sensitivity as in the past. Because of these effects, the sensitizer and heat-sensitive recording material of the present invention can be used for facsimile, P.O.
It is useful for various recording materials such as OS labels.

[Brief Description of the Drawings] [Figure 1] Cross-sectional view showing one embodiment of a heat-sensitive recording material [
FIG. 2: A cross-sectional view showing one embodiment of a heat-sensitive recording material. [FIG. 3] A cross-sectional view showing one embodiment of a heat-sensitive recording material. [FIG. 4]
】Cross-sectional view showing one example of heat-sensitive recording material [Figure 5]
[Fig. 6] A cross-sectional view showing one example of the heat-sensitive recording material [Fig. 7] A cross-sectional view showing one example of the heat-sensitive recording material [Explanation of symbols] 1 Support 2 Layer 3 containing a mixture of a sensitizer, color former and color developer Layer 4 a mixture of a sensitizer and color former 4 Layer 5 a mixture of a sensitizer and a color developer 5 A mixture of a sensitizer and a color developer Layer 6 Sensitizer layer 7 Color former layer 8 Color developer layer

Claims (7)

[Claims] Claim 1: The solubility parameter is 9.5 to 13, and the general formula Ar1X(Y)aZAr2-NO2 (1) [wherein Y is an alkylene group having 1 to 4 carbon atoms or 4
alkenylene group; X, Z are O atom, S atom, -COO
-, -COS- or -OCO-; Ar1, Ar2 are
A thermosensitive recording material comprising an aromatic nitro compound (A) represented by a phenyl group which may have a substituent; a represents an integer from 1 to 4] and a fatty acid amide (B) Sensitizer. [Claim 2] Y is -CH2CH2-, Z is -OCO
-, a is 1, Ar1, Ar2 are phenyl groups, number of carbon atoms is 1 or more
The sensitizer according to claim 1, which is an alkylphenyl group or an alkoxyphenyl group having 22 alkyl groups. 3. The layer formed on the support contains at least an electron-donating colorless coloring agent, an electron-accepting color developing substance, and the sensitizer according to claim 1 or 2, and this layer is thermally colorable. A heat-sensitive recording material characterized by: 4. The layer formed on the support is a laminated layer of a lower layer containing the electron-donating colorless color former and the electron-accepting color developing substance and an upper layer containing the sensitizer. The heat-sensitive recording material according to claim 3. 5. The layer formed on the support comprises a lower layer containing the sensitizer and the electron-donating colorless color former, and an upper layer containing the sensitizer and the electron-accepting color developing substance. 4. The heat-sensitive recording material according to claim 3, which is a laminated layer. 6. The layer formed on the support comprises a lower layer containing the sensitizer and the electron-accepting color developer, and an upper layer containing the sensitizer and the electron-donating colorless color former. 4. The heat-sensitive recording material according to claim 3, which is a laminated layer. 7. The heat-sensitive recording material according to claim 3, wherein the layer formed on the support further contains a lubricant.