JPH05117537A - Fluoran compound adduct and color former - Google Patents

Abstract

PURPOSE:To obtain the subject adduct which is an adduct of a 2-anilino-3- methyl-6-(N-diisobutylamino)fluoran with an organic solvent and has the melting point within a prescribed range and is useful as a color former having high coloring sensitivity. CONSTITUTION:ON The objective adduct is obtained by heating 2-anilino-3- methyl-6-(N-diisobutylamino)fluoran in an organic solvent such as toluene or acetone, partially or completely dissolving the 2-anilino-3-methyl-6-(N- diisobutylamino)fluoran, further cooling the resultant mixture or solution to a temperature at which crystals are deposited and recovering the obtained crystals.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a compound used as an electron-donating color former having excellent color forming properties for use in heat-sensitive or pressure-sensitive recording paper, a color former comprising the compound and a method for producing the same.

[0002]

2. Description of the Related Art Thermosensitive recording papers and pressure-sensitive recording papers to which a coloring reaction by contact between a colorless or light-colored electron-donating substance and a colorless or light-colored electron-accepting substance are applied are known as the present information age advances. The demand is increasing.

Among them, in the case of a thermosensitive recording paper provided on a support in which a finely divided electron-donating color former and an electron-accepting developer are carried in a binder so that they do not come into contact with each other, a high speed facsimile can be used. Along with this, there is a strong demand for improvement in the coloring sensitivity of recording paper that develops black in particular. In order to improve the color developing sensitivity of the thermosensitive recording paper, it is effective to improve the color developing agent and the sensitizer which are the constituents, but basically, it is most effective to improve the color developing sensitivity of the color developing agent.

As a compound useful as a color-forming agent having improved color-developing sensitivity as described above, 2-anilino-disclosed in Japanese Patent Application Laid-Open No. 61-144387 filed by the present inventor.
Mention may be made of 3-methyl-6- (N-diisobutylamino) fluorane. This compound, when used for a thermal recording paper, has excellent light resistance, water resistance, and plasticizer resistance in the colored image area and the uncolored background area, and is a black color developing agent having high speed recording property and high coloring sensitivity. It is stated that there is.

The 2-anilino-3-methyl-6- (N-diisobutylamino) fluorane disclosed by the present inventor in Japanese Patent Laid-Open No. 61-144387 is 2- (4-N-diisobutylamino-2-hydroxybenzoyl). ) Benzoic acid and 2
-Methyl-4-alkoxydiphenylamine is condensed in sulfuric acid, the resulting phthalide compound is a caustic solution and heat treatment or a crude target product obtained by heat treatment with ethylene glycol, isopropanol, heating, cooling,
FD- which is a white crystal purified by the method of filtration.
It is a pure substance showing M / Z = 532 of MS (mass spectrum), and its melting point is 168 to 169 ° C.

Generally, if the melting point of the color former is low, it melts with a small amount of heat and comes into contact with the developer, so that the color developing sensitivity becomes high. Therefore, development of a color former compound having a lower melting point is desired.

[0007]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide a compound having a melting point lower than that of the above-mentioned 2-anilino-3-methyl-6- (N-diisobutylamino) fluorane and having improved color development sensitivity. To do.

[0008]

Means for Solving the Problems The present inventor has diligently studied to solve the above-mentioned problems, and found that the above-mentioned 2-anilino-3
-Methyl-6- (N-diisobutylamino) fluorane is capable of at least partially dissolving by heating with an organic solvent of some kind and then forming an adduct with the organic solvent when cooled, and the addition of the adduct. Compared with the pure 2-anilino-3-methyl-6- (N-diisobutylamino) fluorane crystal having a melting point, it is actually lowered by about 30 to 60 ° C., and it is extremely useful as a color former having high color developing sensitivity. Found. The present invention has been completed based on this finding.

That is, the present invention is an adduct of 2-anilino-3-methyl-6- (N-diisobutylamino) fluorane and an organic solvent, the melting point of which is 110 ° C to 140 ° C.
It provides a compound in the range of ° C.

Further, the present invention comprises an adduct of 2-anilino-3-methyl-6- (N-diisobutylamino) fluorane and an organic solvent, the melting point of which is 110 ° C to 140 ° C.
It provides a color former in the range of ° C.

Further, the present invention provides that the mixture or solution obtained by heating 2-anilino-3-methyl-6- (N-diisobutylamino) fluorane in an organic solvent to partially or completely dissolve it, Cool to a temperature where crystals will precipitate,
The present invention also provides a method for producing the above compound or color former, which comprises collecting the obtained crystals.

In the adduct of the present invention, 2-anilino-3-methyl-6- (N-diisobutylamino) fluorane and an organic solvent are bound to each other to give a pure 2-anilino-3-. Melting point is significantly lower than that of methyl-6- (N-diisobutylamino) fluorane, 110-140 ° C.
It is characterized by being in a range of degrees. Where the melting point is 1
An adduct having a temperature lower than 10 ° C. is too sensitive to heat and is not suitable as a color former for thermal paper. Examples of the organic solvent include toluene, chlorobenzene, o-xylene, and m.
-Benzene having 1 to 3 substituents selected from methyl groups such as xylene and p-xylene and halogen atoms,
Examples thereof include halogenated hydrocarbons having about 1 to 3 carbon atoms such as 1,2-dichloroethane, acetone, and tetrahydrofuran, but are not limited thereto.

The adduct of the present invention can be manufactured as follows. That is, first, 2-anilino-3-methyl-6-
(N-Diisobutylamino) fluorane is added to an appropriate amount of the above organic solvent and heated to at least partially dissolve. The starting material, 2-anilino-3-methyl-6- (N-
As the diisobutylamino) fluorane, as described in JP-A-61-144387, those purified by isopropanol are preferable, but not limited to this, those purified by another solvent or crude It may be one. The amount of the organic solvent used is appropriately selected from a wide range, but depending on the solubility in the solvent, 2-anilino-
It is preferably about 1 to 10 times by weight that of 3-methyl-6- (N-diisobutylamino) fluorane. The heating temperature is 2-
Anilino-3-methyl-6- (N-diisobutylamino) fluorane is preferably at a temperature close to the boiling point of the solvent so that the amount of insoluble portion during heating in the organic solvent used is small. Usually, the boiling point of the organic solvent used is lower than 10 ° C.
A lower temperature range is preferred. The crystals of the above-mentioned fluoran compound as a raw material may be at least partially dissolved in an organic solvent, but it is generally preferable to completely dissolve them. The heating time may be short in the case of being completely dissolved in heat, but it may be long in the case of being partially dissolved. Generally, the heating time is preferably about 10 minutes to 3 hours. Further, in order to promote the dissolution, it is also possible to raise the temperature above the boiling point of the solvent under pressure.

The mixture or solution thus obtained is then cooled to precipitate crystals. The cooling temperature varies depending on the concentration of the raw materials, the organic solvent used, etc., but may be a temperature at which crystals can be precipitated. Generally, 0-15 ° C
A degree is preferable. The cooling time is not particularly limited as long as the crystals are precipitated, but generally 1 to 12 hours is preferable.

The crystals thus precipitated are the adduct of the present invention. The precipitated crystals can be isolated by a commonly used isolation means such as filtration. The isolated crystal can be washed with a low boiling point inert solvent such as n-hexane, if necessary. Then, at a temperature of about 80 to 105 ° C,
The compound of the present invention is obtained by drying for about 1 to 5 hours.

The thus obtained adduct of 2-anilino-3-methyl-6- (N-diisobutylamino) fluorane of the present invention with an organic solvent has a melting point and a differential thermal analysis (DT).
A) and thermogravimetric (TG) findings are shown in Table 1 in comparison with pure 2-anilino-3-methyl-6- (N-diisobutylamino) fluorane.

[0017]

[Table 1]

2-anilino-3-methyl-6- (N-diisobutylamino) fluorane, which has been repeatedly purified with isopropanol, has a melting point of 168 to 169 ° C. and has an endotherm at 167 ° C. by differential thermal analysis (DTA). In thermogravimetric measurement (TG), there was no change up to 200 ° C. In addition, FD-MS shows M / Z = 532, and the purity by high performance liquid chromatography (HPLC) is 99.8%, so it is considered to be a pure product.

On the other hand, in the adduct of the present invention, as shown in Table 1, from the findings of DTA and TG, the adduct was decomposed when it reached a melting state by heating,
Part of the added organic solvent is released. But,
At a temperature of 100 ° C., even if it is kept for a long time, the added organic solvent is not released. Therefore, in the crystalline state of the adduct of the present invention, the organic solvent is considered to form a weak bond with 2-anilino-3-methyl-6- (N-diisobutylamino) fluorane. Also, Cu-K
The X-ray diffraction diagram showing the relationship between the diffraction angle (2θ) of the X-ray diffraction by the α-ray method and the diffraction intensity shows a large difference between the pure product and the adduct.

Furthermore, the adduct with the organic solvent of the present invention is
In the same manner as described above, the compound can be converted into an adduct with the other organic solvent by heating and dissolving in another organic solvent, cooling and crystallization.

The adduct of the present invention is a raw material (pure product) in which the added organic solvent is removed by boiling the adduct in a slightly large amount of isopropanol for several hours, then cooling and filtering. The same result can be obtained by using n-butanol instead of isopropanol.

[0022]

EFFECTS OF THE INVENTION The adduct of the present invention is mainly composed of a fluoran compound raw material and has a melting point of 110 to 140.
Since it is in the low temperature range of 0 ° C., it is particularly useful as a color-forming agent for thermosensitive recording paper having high color-developing sensitivity. That is, the black color thermosensitive recording paper using the adduct of the present invention as a color former is a conventionally known color former such as 2-anilino-3-methyl-6-diethylaminofluorane and 2- (2'-chloroanilino). -6-diethylaminofluorane, or 2-anilino-3-methyl-6- (N- which does not form an adduct
Particularly, the thermosensitive coloring sensitivity is excellent as compared with the case where diisobutylamino) fluorane is used as the coloring agent.

The adduct of the present invention is useful not only as a color former for heat-sensitive recording paper but also as a color former for pressure-sensitive recording paper.

[0024]

EXAMPLES The present invention will be described in more detail with reference to the following Reference Examples and Examples.

Reference Example 1 2- (4-N-diisobutylamino-) was added to 550 g of concentrated sulfuric acid.
2-Hydroxybenzoyl) benzoic acid (melting point 195.5
˜196.5 ° C.) 73.9 g and 2-methyl-4-methoxy-diphenylamine 42.6 g are dissolved, 15-2
The mixture was stirred at 0 ° C for 10 hours and poured into 5 kg of ice water.

The precipitated phthalide compound was filtered, washed with water, and then suspended in 1 liter of water to obtain 300 g of toluene.
And add caustic soda 50g, keep it at 85 ℃ for 2 hours,
It was stirred.

When hot, the aqueous layer was removed by liquid separation, and the toluene layer was washed twice with hot water. The obtained toluene solution of fluoran was treated with activated carbon at 100 ° C. for 30 minutes, filtered to remove the activated carbon, and toluene was distilled off under reduced pressure.

After adding 160 g of isopropanol, boiling for 1 hour, cooling to 10 ° C. and filtering, boiling again with 150 g of isopropanol for 1 hour, cooling to 10 ° C., filtering, and washing with n-hexane 105 It was dried at ℃ for 3 hours.

Thus, 2-anilino-3-methyl-6
78.8 g of-(N-diisobutylamino) fluorane was obtained as white fine crystals. The melting point was 168-169 ° C and the purity by HPLC was 99.8%. FD-
MS was M / Z = 532.

Example 1 Toluene was distilled off under reduced pressure from the toluene solution treated with activated carbon in Reference Example 1, cooled to 10 ° C., 200 g of isopropanol was added, and the mixture was sufficiently stirred at 10 ° C. and filtered. It was washed with n-hexane and dried. The melting point of the obtained crystal was 129 to 131 ° C. This crystal 85.
1 g was boiled with 100 g of toluene for 1 hour and cooled to 10 ° C. for 6 hours to precipitate crystals. It was filtered, washed with n-hexane and dried at 110 ° C. for 5 hours. In this way, 80.0 g of white fine crystals are obtained, the melting point of which is 130.
It was ~ 131 ° C.

Examples 2 to 9 with a melting point of 168 to 169 ° C. obtained according to Reference Example 1
After adding 5 g of anilino-3-methyl-6- (N-diisobutylamino) fluorane to the organic solvents listed in Table 2 below and heating at the temperature and time shown in Table 2, at the temperature and time shown in Table 2. Cooled. The obtained crystals were collected by filtration, washed with n-hexane and then dried at 100 ° C for 5 hours. The melting point of the adduct of the present invention thus obtained is shown in Table 2.
Also described in.

[0032]

[Table 2]

Example 10 To 275 g of 96% sulfuric acid, 37.0 g of 2- (4-N-diisobutylamino-2-hydroxybenzoyl) benzoic acid and 21.2-methyl-4-methoxy-diphenylamine.
Dissolve 3 g and stir at 15-20 ° C. for 12 hours, then
It was poured into 2500 g of ice water. The precipitate was filtered, washed with water and then suspended in 500 g of water, to which 150 g of o-xylene and 25 g of caustic soda were added, and the mixture was heated to 85 ° C. for 3 days.
The mixture was kept warm for an hour and stirred.

At the time of heating, the water layer is removed by liquid separation operation, and o-
After washing the xylene layer twice with hot water, the o-xylene solution was treated with activated carbon at 100 ° C. The o-xylene solution was concentrated under reduced pressure to remove about 100 g of o-xylene, then cooled and the precipitate was filtered and washed with a small amount of o-xylene.

The cake thus obtained was charged in 200 g of o-xylene, and dissolved by boiling and stirring for 1 hour and then cooled at 5 ° C. for 6 hours. The precipitated crystals were filtered, washed with n-hexane and washed at 100 ° C. And dried for 5 hours. The yield of the obtained crystals is 4
At 0.5 g, the melting point was 123-124 ° C.

Claims (3)

[Claims] 1. 2-anilino-3-methyl-6- (N-
A compound which is an adduct of diisobutylamino) fluorane and an organic solvent and has a melting point in the range of 110 ° C to 140 ° C. 2. Anilino-3-methyl-6- (N-
A color-forming agent comprising an adduct of diisobutylamino) fluorane and an organic solvent and having a melting point in the range of 110 ° C to 140 ° C. 3. 2-anilino-3-methyl-6- (N-
Diisobutylamino) fluorane is heated in an organic solvent to partially or completely dissolve, and the resulting mixture or solution is cooled to a temperature at which crystals precipitate, and the obtained crystals are recovered. Item 2. A method for producing the compound according to Item 1.