JPS6020403B2 - Fluoran compounds - Google Patents

Description

[Detailed description of the invention]

The present invention relates to novel fluoran compounds. More specifically, the present invention provides 2-
This invention relates to a fluoran compound having an (acylphenyl)amide/group. Known fluoran compounds having a 2-(substituted phenyl)amino group include
No. 2406, Japanese Patent Publication No. 48-43296, Japanese Patent Publication No. 49-32767, Japanese Patent Publication No. 51-23204, and Japanese Patent Publication No. 49-134526. The fluoran compounds disclosed in these documents are used as dye precursors for thermal recording paper, ordinary thermal recording paper, pressure-sensitive copying paper, and the like. However, thermal recording paper using these fluoran compounds as dye precursors has poor color density,
It has shortcomings in color development density, color development start temperature, color rise, etc., and cannot exhibit sufficient performance as a thermosensitive recording paper. For example, it is disclosed in the above-mentioned document 2
-Anilino-3-methyl-6-diethylamino-fluorane has the disadvantage that it partially develops color during the production of thermal recording paper, increasing the background color density of the recording paper, and 2-(2-chlorophenyl)amino-6 Thermal J recording paper using -jethylamino-fluoran has a low background color density, but the color development start temperature is too high**, the color development is insufficient, and 2-anilino-3-methyl-61N-methyl-N - Cyclohexylamino-fluorane has insufficient or insufficient color development. The rise of color development is expressed by the value multiplied by 100 at the maximum slope of the color development density-color development temperature curve, where the color density is taken as the vertical axis and the color development temperature is taken as the horizontal axis. It is something. The present inventors have found that there is almost no pond coloration, the color density is high,
As a result of intensive research into fluoran compounds used in thermal recording paper, which have a low color initiation temperature and excellent color development, we have found that fluoran compounds having a 2-(acylphenyl)amino group have the extremely excellent performance described above. I saw that I had it and put it out. That is, the present invention is based on the general formula (
In the formula, R and R2 are a methyl group or an ethyl group, and R3 is a lower alkyl group. ) is a fluoran compound represented by The fluoran compound represented by the general formula [1] of the present invention is a colorless or slightly colored solid that is stable in the atmosphere, and immediately forms a deep red-black or green-black pigment when it comes into contact with an acidic substance. The developed dye has excellent storage stability and has sufficient utility as a dye precursor. The fluoran compound represented by the above general formula [1] of the present invention is produced by the following method [1 or '21]. '1--General formula (wherein, R is a hydrogen atom or a lower alkyl group, R
3 has the same meaning as defined in general formula [1]. ) and a penzophenone compound represented by the general formula (wherein R and R2 have the same meanings as defined in general formula [1]) in the presence of a condensing agent such as concentrated sulfuric acid. The reaction is then carried out at a temperature of 0 to 80°C for several hours. After the reaction, the reaction mixture is added to water, an aqueous sodium hydroxide solution is added to adjust the pH to 8 to 10, and the precipitate is collected by filtration. Add toluene and a 5-10% aqueous sodium hydroxide solution to the cake, stir under reflux for 1-3 hours, separate the toluene layer, collect it, wash with water, concentrate, and collect the precipitated crystals by filtration. . By drying the crystals, a slightly colored fluoran compound having a 2-(acylphenyl)amino group represented by the general formula [1] is produced with high purity and high yield. If necessary, recrystallize from volatile organic inert solvents such as toluene, acetone, butyl acetate, etc. A fluoran compound having an amino group at the 2-position represented by the 2' general formula (wherein R and R2 have the same meanings as defined in the general formula [1]) and an acyl-substituted promo or chlorobenzene. The fluorazo compound represented by the general formula [1] is produced by reacting copper powder with iodine in a volatile organic inert solvent as a catalyst.The method of [1] above is preferred for production. The above general formula [B] used in the present invention
Representative diphenylamines represented by are 4-methoxy-acetyl-diphenylamine, 4
-methoxy-3'-acetyl-diphenylamine, 4-methoxy-4'-pro/gnoyl-diphenylamine,
4-methoxy 4'-butanoyl diphenylamine,
Examples include 4-methoxy-4'-i-butanoyl-diphenylamine, 4-hydroxy-4'-acetyl-diphenylamine and 4-ethoxy-4'-acetyl-diphenylamine. Among the above diphenylamines, those in which the 4-position is substituted with an alkoxy group are preferred from the viewpoint of production. In addition, as the penzophenone compound represented by the above general formula [m] used in the present invention, 2-(2-hydroxy-4-dimethylamino)penzoylbenzoic acid and 2-(2-
Examples include hydroxy-4-jethylamino)penzoylbenzoic acid. The above general formula used in the present invention [
The aminofluoranes represented by W] are 2-amino-6-dimethylaminofluorane and 2-amino-6-diethylaminofluorane. The acyl-substituted promo or chlorobenzene used in the present invention includes 4-acetyl-promobenzene,
4-acetyl-bromobenzene, 3-acetyl-promobenzene, 3-acetyl-oobenzene, 4-propanoyl-chlorobenzene, 4-propanoyl-chlorobenzene, 4-butanoyl-bromobenzene, 4-i-butanoyl-bromobenzene and 4-i-butanoyl-chlorobenzene. Condensing agents used in the present invention include concentrated sulfuric acid, acetic anhydride, phosphoric acid, polyphosphoric acid, phosphorus oxychloride, and zinc chloride. For manufacturing purposes, preferably the above general formula

This method uses concentrated sulfuric acid, which is a condensing agent as well as a solvent for diphenylamine represented by [0] and a penzophenone compound represented by general formula [m]. Next, typical manufacturing methods and usage examples of the 2-(acylphenyl)amino group-containing fluoran of the present invention are shown in the following examples. Example 1 2-(4-acetylphenyl)amino-6-ethylamide/-fluoran [Compound M. 1]. Add 12.5 ml of 2-(2-hydroxy-4-jethylamino)penzoylbenzoic acid to 150 ml of 95% sulfuric acid, dissolve completely at a temperature of about 200 ml, and then dissolve 4-methoxy-4'-acetyl-diphenylamine. 9.7 evening added 2
The reaction was carried out at a temperature of 0 to 30q0 for 48 hours. After the reaction, the reaction mixture was added to 1 cup of ice water, followed by 1 cup of ice water.
% aqueous sodium hydroxide solution to adjust the pH to 8.0,
The precipitate was collected by filtration, and 300% of toluene was added to the cake.
After adding M and 150 g of a 10% aqueous sodium hydroxide solution and stirring under reflux for 2 hours, the toluene layer was separated, washed with water and concentrated, and the precipitated crystals were collected by filtration. The crystals were dried to obtain 11.6 g of yellowish-white 2-(4-acetylphenyl)amino-6-diethylaminofluorane. The melting point of the obtained fluoran was 192 to 19,500. This fluoran compound had a melting point of 194-1970 by recrystallizing it from acetone, and its elemental analysis values were as follows, and they matched within the range of error. 4-Methoxy-acetyl-diphenyl-amine used in Example 1 was produced by the following method. Anhydrous potassium carbonate to a mixture of 49.6% of 4-methoxy N-acetylanilino and 59.7% of 4-promoacetophenone;
Steel powder and iodine were added and reacted at 170 to 175°C for 30 hours. Subsequently, potassium hydroxide and isoamyl alcohol were added to this reaction mixture and reacted at 125 to 130 qo for 2 hours, then toluene was added, the toluene layer was washed and dispersed with water, and after concentrating, methanol was added to the residue, The precipitated crystals were collected by filtration. The crystals were dried and turned into pale yellow 4-methoxy-4'-acetyl diphenylamine 34.
．． 7 evenings were obtained. The melting point of this thing is 115 to 11 pi○
Met. Example 2 2-(4-propanoylphenyl)amino-6-jethylaminofluoran [Compound M. 0]. In 150 g of 95% sulfuric acid, 12.5 g of 2-(2-hydroxy-4-jethylamino)penzoyl-benzoic acid and 10.2 g of 4-methoxy-4'-propanoyl diphenylamine (melting point 116-117.5 q0) were added. Reacted and treated as in Example 1, colored pale blue, melting point 180
8.5 pieces of crude crystals of ˜19,300 were obtained. By recrystallizing the obtained crude crystals from acetone,
6.2 volumes of 2-(4-probanoyl phenyl)amino-6-diethylaminofluorane were obtained, which was almost colorless and had a melting point of 199-203 degrees. Example 3 2-(4-butanoylphenyl)amino-6-jethylaminofluoran [Compound M. m]. In 150 g of 95% sulfuric acid, 12.5 g of 2-(2-hydroxy-4-ethylamide/)penzoyl-benzoic acid and 10.8 g of 4-methoxy-4'-butanoyl-diphenylamine (melting point .94-90) were added. was reacted and treated in the same manner as in Example 1, and was colored pale blue with a melting point of 121 to 150.
Crude crystals of qo 9.5 were obtained. By recrystallizing the obtained crude crystals from butyl acetate, almost colorless 2-(4-butanoylphenyl)amino-6-diethylaminofluorane with a melting point of 157 to 16 mm was obtained. Ta. Example 4 2-(3-acetylphenyl)amino-6-jethylamino-fluoran [compound base. W]. In 150 g of 95% sulfuric acid, 12.5 g of 2-(2-hydroxy-4-jethylamino)penzoyl-benzoic acid and 4-methoxygoacetyl-diphenylamine (melting point .7
7 to 80 qo) and 9.7 qo) were reacted in the same manner as in Example 1,
Processed and colored pale yellow Melting point 194-199q0
11.5 days of crude crystals of 2-(3-acetylphenyl)amino-6-diethylaminofluorane were obtained. The obtained crude crystals were recrystallized from acetone to obtain the above-mentioned fluoran compound having a pale yellowish white color and a melting point of 200 to 203 oC. Usage Example 1 Compound produced in Example 1 [M. 1] 2.0% water and 1% by weight
20 minutes of an aqueous polyvinyl alcohol solution was added, and the mixture was dispersed and mixed using a ball mill at room temperature for 2 hours to produce a colorless slurry in which the particle size of the compound was about 3 microns. On the other hand, 10 parts of water and 40 parts of an aqueous solution of polyvinyl alcohol containing 7 parts by weight were added, and the mixture was dispersed and mixed using a ball mill at room temperature for 2 hours to produce a slurry. The average particle size of the solid material in this slurry is approximately 5
It was a micron. Then, both slurries were mixed and heated at room temperature.
A mixed slurry was produced by stirring for a long time to uniformly disperse and mix. This mixed slurry was coated on one side of plain paper for 50 minutes using a wire bar coater (winding; 0.35 side ◇) to ensure a uniform film thickness and a coating amount of the compound of 1.5 per square meter of paper. It was applied in the evening and air-dried at room temperature. In this way, a heat-sensitive recording sheet having an almost colorless heat-sensitive layer was prepared. Hereinafter, this heat-sensitive recording sheet will be used as M. Abbreviated as A. Similarly, [Compound No. 0〕〜
[Compound land. W] was used to record heat-sensitive recording sheet No. B～N
o. Created D. Furthermore, for comparison, a known 2-anilino-3-methyl-6-diethylaminofluorane [Ihi compound M-V]
, 2-anilino-3-methyl-6-N-methyl-N-cyclohexylaminofluorane [Compound Yuzu. ] and 2-(2-chlorophenyl)amino-6-diethylamino-fluorane [compound M. Similarly, the heat-sensitive recording sheet M. E-M. I created G.
The following tests were conducted using these thermosensitive recording sheets.
■ Color development performance test of heat-sensitive recording sheet Heat-sensitive recording sheet No.
．． A~Snake. D and control snakes. E~No. G was heated at a temperature of 150°C for 5 seconds, and the various color phases, color density, and background color density were measured using a Macbeth reflection densitometer RD-51 semi-sei with a black filter (Ratten #106). ■Measurement of coloring characteristic values of thermosensitive recording sheets.Thermosensitive recording sheets. A～No. D and control no. E
~M. When G is heated for 5 seconds in the temperature range of 80oo to 160oo to develop color, the color density at each temperature is described with ■**
The temperature at which color development started and the rise of color development were calculated from the relationship between temperature and color density at that time. The results of the above coloring performance test (1) and coloring characteristic values (2) are shown in the following table. Color development performance of thermosensitive recording sheet Color development characteristic value Note 1: Heating color development was performed using a Rhodiaceter-type Thermotest tester (manufactured by the French National Textile Research Institute) at a heating temperature of 8.
The test was carried out under the following conditions: 0 to 160°C, heating time 5 seconds, and load 100/c. Note 2: The rise of color development is calculated from the tana at the maximum slope in the color density-color temperature curve using the following formula. Rise of color development = 100 x tana From the above test (1) and the measurement results (2), the heat-sensitive recording sheet using the fluoran compound of the present invention has a higher temperature than the heat-sensitive recording sheet using the known fluoran compound shown as a control. It was confirmed that it was excellent overall, and in particular had a high color rise, which is extremely important in practical use.

Claims (1)

[Claims] 1. A fluoran compound represented by the general formula ▲There are numerical formulas, chemical formulas, tables, etc.▼ (In the formula, R_1 and R_2 are a methyl group or an ethyl group, and R_3 is a lower alkyl group.) 2. The fluoran compound according to claim 1, wherein the fluoran compound is 2-(4-acetylphenyl)amino-6-diethylamino-fluoran. 3. The fluoran compound according to claim 1, wherein the fluoran compound is 2-(4-propanoylphenyl)amino-6-diethylamino-fluoran. 4. The fluoran compound according to claim 1, wherein the fluoran compound is 2-(4-butanoylphenyl)amino-6-diethylamino-fluoran. 5. The fluoran compound according to claim 1, wherein the fluoran compound is 2-(3-acetylphenyl)amino-6-diethylamino-fluoran.