JPH0421675B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides 3-dibutylamino-6-methyl-7
- Concerning crystal modification of anilinofluorane. More specifically, there are strong peaks at diffraction angles (2θ) of 6.9° and 18.9°, 11.0° and
This invention relates to a crystal modification of 3-dibutylamino-6-methyl-7-anilinofluorane (hereinafter referred to as β-type modification) characterized by an X-ray diffraction diagram showing an intermediate intensity peak at 18.5°. Conventionally, a pressure-sensitive copying method is used to obtain colored images using a color reaction that occurs when an electron-donating colorless dye (color former) and an electron-accepting substance (color developer) are brought into contact with each other using physical force or heat. Alternatively, the thermal recording method is well known, and the 3-dibutylamino-6
-Methyl-7-anilinofluorane is used as a coloring agent. Such a coloring agent for pressure-sensitive copying or heat-sensitive recording is required to be excellent in coloring characteristics such as coloring sensitivity, coloring density, background coloring property, and various fastnesses after coloring. 3-
Dibutylamino-6-methyl-7-anilinofluorane is described as a coloring agent in Japanese Patent Publication No. 48-43296, but this is because its normally obtained crystalline form is used as a coloring agent. However, it is not possible to obtain sufficiently satisfactory results in terms of the above-mentioned coloring properties, especially in terms of self-coloring properties and yellowing over time. The present inventors have intensively investigated the relationship between the crystal form of 3-dibutylamino-6-methyl-7-anilinofluorane, the color development characteristics of pressure-sensitive or heat-sensitive recording materials using the same, and yellowing over time. As a result, it was found that this compound has two types of crystal modifications. In other words, it is a pale yellow-green crystal, and when used as a coloring agent for pressure-sensitive or heat-sensitive recording, it has excellent coloring sensitivity and various fastnesses of colored images, but it is said to have a high self-coloring property and yellowing of the skin over time due to sunlight. Crystal modification (hereinafter referred to as α-form transformation) has the disadvantage of a milky white color, and the color development sensitivity and color fastness of color images are equivalent to α-type transformation, but self-color development and yellowing of the skin due to sunlight over time. Crystal with very little modification (β-type modification)
There are two types. 3-Dibutylamino-6-methyl-7-anilinofluorane is produced according to a conventional method, for example, as follows. That is, 2-(4'-dibutylamino-2'-hydroxybenzoyl)benzoic acid and 4-
Methoxy-2-methyl-diphenylamine was reacted with sulfuric acid (dehydration condensation agent) at 20°C for 5 hours, then the reaction solution was poured into ice water, the resulting precipitate was separated as necessary, and then a caustic soda aqueous solution was added. The mixture is closed by heating under reflux at 80 to 85° C. for 2 hours with a mixture of toluene and toluene. After the reaction solution is allowed to stand still and separated, the organic solvent layer is concentrated, and methanol or ethanol is added to this to precipitate crystals (α-type transformation). amount of chlorinated benzene such as monochlorobenzene, dichlorobenzene, trichlorobenzene, etc. at 70 to 150℃ for 30 minutes to 3
By treating for 1 to 2 hours, preferably at 90°C to 120°C, β-type transformation can be obtained. In addition, after removing phthalide, which is an intermediate product in the synthesis of 3-butylamino-6-methyl-7-anilinofluorane, the ring was closed with the above-mentioned mixture of chlorinated benzene and caustic aqueous solution, and then the liquid was separated. β-type modification can also be obtained by treating a chlorinated benzene solution containing 3-dibutylamino-6-anilinofluorane at the temperature and time described above. Next, the α-type modification and β-type modification of 3-dibutylamino-6-methyl-7-anilinofluorane will be explained with reference to the drawings. FIGS. 1 and 2 are diagrams obtained by powder X-ray diffraction, in which the diffraction state of Cu-Kα rays was recorded using a proportional counter. Figure 1 shows the β-type transformation, with strong peaks at diffraction angles (2θ) of 6.9° and 18.9°,
It shows intermediate intensity peaks at 11.0° and 18.5°.
Figure 2 shows the α-type transformation, and the diffraction angle (2θ)
Strong peaks at 11.6° and 21.1°, 6.9°, 12.0°, 17.8
It shows intermediate intensity peaks at 21.5° and 21.5°. (An error of about ±0.2° is allowed in the representation of the diffraction angle.) These drawings clearly show the differences between each transformation. In the treatment method described above, it is determined whether the α-type modification has been converted to the β-type modification of the present invention by measuring an X-ray diffraction pattern, but a simpler identification method is
You can also tell by the fact that the powder color of the type metamorphosis is pale yellow, while the β type metamorphosis is milky white. It can also be determined by measuring the melting point of the sample, and α-type transformation is detected.
mp148-152℃, while β-type metamorphosis is m.
p. Shows 180-184℃. Next, the present invention will be specifically explained with reference to Examples and Comparative Tests. (In Examples and Comparative Tests, parts indicate parts by weight) Reference Example 3 Synthesis of dibutylamino-6-methyl-7-anilinofluorane 2-(4'-dibutylamino-2'-hydroxybenzoyl)benzoin 36.9 parts of acid, 4-methoxy-2-
21.3 parts of methyl-diphenylamine in 200ml of concentrated sulfuric acid
After reacting at 0 to 5°C for 20 hours, the resulting crystals were filtered and washed with 1 part of water to give a phthalide cake (3-(4-dibutylamino-2-hydroxyphenyl)-3- (5-anilino-2-methoxyphenyl)phthalide) is obtained. Add the phthalide cake to 200 ml of toluene and 100 ml of water, neutralize with 28% caustic soda, add 4 parts of caustic soda, and stir under heating under reflux for 3 hours. After standing still, the toluene layer was separated and concentrated until a syrup-like substance was obtained while maintaining the temperature above 70°C, and then 300 ml of methanol was added to precipitate crystals. 42 parts of α-type modification showing a diffraction pattern were obtained. (mp=148～
152℃) Example 1 42 parts of the above α-type modification was converted into o-dichlorobenzene.
200 parts were added and treated at 105-115°C for 1 hour to obtain 38 parts of milky white β-type modification. This gave an X-ray diffraction pattern as shown in FIG. (mp=180~184
℃) Example 2 A phthalide cake obtained in the same manner as in Example 1 above was added to a mixed medium consisting of 200 parts of monochlorobenzene and 100 parts of water, neutralized with 28% caustic soda, and then 4 parts of caustic soda was added to give a mixture of 80 to 85%. Stir at ℃ for 3 hours. After standing still, the monochlorobenzene layer is 110-120
C. for 90 minutes, 39 parts of the β-type modification having a milky white X-ray diffraction pattern as shown in FIG. 1 was obtained. (mp=180~184℃) Comparative Test The following comparative test was conducted to compare the effects of α-type and β-type modifications of 3-dibutylamino-6-methyl-7-anilinofluorane on thermal recording paper. did. [A] Liquid α-type or β-type modified 3-dibutylamino-6
-Methyl-7-anilinofluorane 15.0 parts Gohsenol GL-05H (25% aqueous solution) (Nippon Gosei) 12.0 parts water 33.0 parts [B] Liquid bisphenol A 34.5 parts Gohsenol GL-05H (25% aqueous solution) 20.0 parts water 110.0 parts [A] and [B] solutions were prepared by separately grinding and dispersing both solutions [A] and [B] using a sand grinder so that the average particle size was 1 to 3 μm. In addition, a mixture consisting of the following composition was ground and dispersed using a sand grinder for 2 hours to prepare liquid [C]. [C] Liquid Aramide HT-P (manufactured by Lion Akzo)
29.5 parts Calcium carbonate 60.0 parts Gohsenol GL-05H (25% aqueous solution) 20.0 parts Water 109.0 parts Then [A] solution: [B] solution: [C] solution 6:47:
47 to prepare a thermosensitive coloring layer forming solution,
The dry solid content on the surface of high-quality paper with a basis weight of approximately 50g/ ^m2 is 50g/m2.
g/ ^m2 , dried, α-type transformation, β
A thermosensitive recording paper with a shape change was obtained. The following table shows the results of a comparative test using thermosensitive recording paper of α-type transformation and β-type transformation. 【table】

[Brief explanation of drawings]

Figures 1 and 2 show 3-dibutylamino-6
- X-ray diffraction diagrams of β-type modification and α-type modification of methyl-7-anilinofluorane. In the drawings, the horizontal axis represents the diffraction angle (2θ), and the vertical axis represents the diffraction intensity.

Claims (1)

[Claims] 1 Strong peaks at diffraction angles (2θ) of 6.9° and 18.9°, 11.0° and 18.5 in X-ray diffraction using Cu-Kα rays
3-dibutylamino-6-methyl-7, characterized by an X-ray diffraction diagram showing a peak of intermediate intensity at °
-Crystal modification of anilinofluorane.