JPH0621229B2 - Fluoran derivative, method for producing the same, and thermosensitive coloring component for recording material - Google Patents

Description

TECHNICAL FIELD The present invention relates to a novel fluorane derivative and a method for producing the same, and a thermosensitive color-forming component for a recording material, which comprises these derivatives.

[Conventional technology]

A heat-sensitive recording material using an electron-donating fluoran dye and an electron-accepting compound is widely known (for example, JP-B-51-23204 and JP-A-57-315).
91, 58-52356 and 60-36568).
And, as such a fluoran dye, for example, as a black chromophore, 3-N, N-diethylamino-
7-o-chloroanilinofluorane, 3- (N-methyl-N-cyclohexylamino) -6-methyl-7-anilinofluorane and the like.

The minimum performance required for such a recording material is: 1) sufficient color density and color sensitivity, 2) no fog, and 3) sufficient fastness of the color body after color development. , Etc. However, at present, none of them completely satisfy all of these performances.

[Problems to be solved by the invention]

In particular, in the thermal recording paper using the conventional fluoran dye as described above, there is a drawback that when the coloring portion is contacted with a plasticizer, oil, an organic solvent or the like, the color is erased.

The inventors of the present invention have conducted extensive studies to eliminate the drawbacks of the conventional fluoran dyes, and as a result, used a novel compound obtained by condensation of a specific fluoran compound and a ketone as a thermosensitive color-forming component. In this case, it was found that the fastness of the coloring portion of the obtained recording material was remarkably improved, and the present invention was completed.

[Means for solving problems]

Therefore, according to the present invention, a fluoran derivative represented by the following general formula I is provided.

In the above formula, R ₁ and R ₂ may be the same or different and each represents C _1-9 alkyl, C _3-6 cycloalkyl, phenyl or alkyl (C _1-4 ) -substituted phenyl. , R ₃ and R _{4, which} may be the same or different, each represents C _1-6 alkyl or phenyl, or R ₃ and R ₄ together with the carbon atom to which they are attached. To form a 5- to 8-membered cycloalkane.

The fluoran derivative according to the present invention includes various plasticizers,
Since the solubility in oil, organic solvent, etc. is relatively low, the fastness of the colored portion of the heat-sensitive recording material can be remarkably improved. Further, although these fluoran derivatives are almost white substances themselves, when they are brought into close contact with an electron-accepting substance (developing agent) such as bisphenol A and silica gel, they develop a good black color tone. It has properties and is extremely useful as a heat-sensitive coloring component of a heat-sensitive recording material.

In compounds of general formula I, R ₁ and R ₂ or R ₃ R ₄
The alkyl as may be a straight chain or a branched chain. When R ₃ and R ₄ together with the carbon atom to which they are attached form a cycloalkane, examples of such cycloalkanes include cyclopentanone, cyclohexanone, cycloheptanone and cyclooctane. There is.

In compounds of general formula I The following groups are preferable as the group.

The fluoran derivative of the general formula I is represented by the following general formula II, [In the above formula, R ₁ and R ₂ represent the same as defined above], and 2 mol of the compound represented by the following general formula III: [Wherein R ₃ and R ₄ represent the same as defined above] and can be produced by reacting with 1 mol of a ketone.

Specifically, for example, 2 mol of the fluorane compound of the general formula II and 1 mol of the ketone of the general formula III are combined with ferric chloride, calcium chloride, using a condensing agent such as sulfuric acid, hydrochloric acid or phosphoric acid.
The reaction is carried out at a temperature of 30 to 80 ° C. for 5 to 100 hours in the presence of a catalyst such as boric acid, hydrogen sulfide and alkyl mercaptan. Then, the reaction product is poured into ice water, and after neutralization, the precipitate is separated, dissolved in ethyl acetate, washed with a 2% aqueous sodium hydroxide solution, and then concentrated, and an organic solvent such as toluene, benzene, isopropyl alcohol, or acetone. The desired product can be obtained in high purity by recrystallizing from.

A recording material can be prepared by a known method using the fluorane derivative of the general formula I as a thermosensitive color-forming component. For example, US Patents 2548366, 2800457 and 2
According to the method described in 800458, a thermosensitive recording material can be obtained by using the compound of the general formula I as a color forming component.

〔Example〕

 Hereinafter, the present invention will be further described with reference to examples.

[Synthesis Example 1] 3- (N-methyl-N-cyclohexylamino) -6-
Methyl-7-anilinofluorane 1g was added to acetone 10m.
1, dissolved in 7 ml of concentrated hydrochloric acid, added with 0.1 g of ferric chloride, and reacted at 60 to 65 ° C for 5 hours. After the completion of the reaction, the reaction solution is poured into 300 ml of ice water to neutralize and precipitate. Next, this precipitate is dissolved in ethyl acetate and washed with a 2% aqueous sodium hydroxide solution. The ethyl acetate layer is separated, dried over anhydrous sodium sulfate, and concentrated. continue,
Isopropyl alcohol was added and recrystallization was performed to obtain 0.8 g of a white powder condensation product. The melting point of this product is 2
It was 06-210 degreeC. Further, it was confirmed from the molecular weight measurement by gel permeation chromatography that it was a condensate of 2 mol of the raw material fluoran compound corresponding to the general formula I.

This product was black on silica gel, and the hue developed by contact with bisphenol A was black green.

[Synthesis Example 2] 1 g of 3- (Np-tolyl-N-ethylamino) -6-methyl-7-anilinofluorane was dissolved in 10 ml of acetone and 7 ml of concentrated hydrochloric acid, and 0.1 g of ferric chloride was added. In addition, 60
React at ~ 65 ° C for 5 hours. After the completion of the reaction, the same post-treatment as in Synthesis Example 1 was performed to give 0.6 g of a white powder condensation product.
Got The melting point of this product was 263 to 269 ° C. According to the molecular weight measurement by gel permeation chromatography, this was a condensate of 2 mol of the starting fluoran compound corresponding to the general formula I.

The product was black on silica gel. Further, the hue developed by contact with bisphenol A or the like was black green.

[Synthesis Example 3] 1 g of 3-diethylamino-6-methyl-7-anilinofluorane was added to 5 ml of methyl ethyl ketone and 5 parts of acetonitrile.
ml, dissolved in 5 ml of concentrated hydrochloric acid, added with 0.1 g of calcium chloride, and reacted at room temperature for 3 days. After completion of the reaction, Synthesis Example 1
The same post-treatment as described in (1) above is performed to obtain a white powder condensation product 0.5
g was obtained. The melting point of this product was 199-204 ° C. According to the molecular weight measurement by gel permeation chromatography, this was a condensate of 2 mol of the starting fluoran compound corresponding to the general formula I.

The product was black on silica gel. Further, the hue developed by contact with bisphenol A or the like was black green.

[Synthesis Example 4] 3- (N-methyl-N-cyclohexylamino) -6-
1 g of methyl-7-anilinofluorane is dissolved in 5 ml of acetophenone, 5 ml of acetolitol and 5 ml of concentrated hydrochloric acid, 0.1 g of calcium chloride is added, and the mixture is reacted at room temperature for 3 days. After the completion of the reaction, the same post-treatment as in Synthesis Example 1 was performed to obtain 0.5 g of a white powder condensation product. The melting point of this product was 200-210 ° C. According to the molecular weight measurement by gel permeation chromatography, this was a condensate of 2 mol of the starting fluoran compound corresponding to the general formula I.

In addition, this product was black on silica gel, and the hue developed by contact with bisphenol A was black green.

[Synthesis Examples 5 to 15] Fluoran derivatives shown in Table 1 below were obtained in the same manner as in Synthesis Examples 1 to 4 using appropriate starting materials.

The compound of Example No. 5 in Table 1 corresponds to the compound of Synthesis Example 1, and similarly, the compounds of Example Nos. 14, 11 and 8 correspond to the compounds of Synthesis Examples 2, 3 and 4, respectively.

Hydrogen nuclear magnetic resonance (H ¹ -NM of the compounds listed in Table ¹
The measured value of R) is shown in Table 2, and the measured value of carbon 13 nuclear magnetic resonance (C ¹³ -NMR) of the same compound is shown in Table 3. Note that C
The corresponding carbon numbers of ^13- NMR are shown in Table 4. Third
The table is displayed by this number.

Example 1 Dispersions A and B were prepared by pulverizing and dispersing the following components using an attritor.

[Dispersion A]

Condensation product obtained in Synthetic Example 1 20 parts by weight 10% aqueous solution of polyvinyl alcohol 20 〃 water 60 〃 [dispersion B] 15 parts by weight of bisphenol A calcium carbonate 5 〃 10% aqueous polyvinyl alcohol 20 〃 water 60 〃 Then [ The solution A and the solution B were mixed and stirred at a weight ratio of 1: 5 to obtain a thermosensitive color developing layer coating solution. This thermosensitive coloring layer coating solution is applied to the surface of commercially available high-quality paper using a wire bar and dried to form a thermosensitive coloring layer having an adhesion amount of 5 g / m ³ , followed by calendering. A thermal recording sheet was created.

[Example 2] A thermosensitive recording sheet was prepared in the same manner as in Example 1 except that the condensation product synthesized in Synthesis Example 3 was used in place of the fluorane condensation product of the liquid A.

[Example 3] A thermosensitive recording sheet was prepared in the same manner as in Example 1 except that the condensation product synthesized in Synthesis Example 4 was used instead of the fluorane condensation product of the liquid A.

Comparative Example 1 In place of the fluorane condensation product of the liquid A in Example 1, 3- (N-methyl-N-cyclohexylamino) -6-methyl 7-anilinofluorane, which has been widely used in the past, is used. A thermal recording sheet was prepared in the same manner except that it was not used.

With respect to the four kinds of recording materials obtained in the above-described Examples and Comparative Examples, a temperature of 150 ° C. and 1
A pressure of kg / cm ² was applied for 0.5 seconds. The surface of the color-developed sample was covered with a soft vinyl chloride wrap film for food packaging containing a plasticizer, and 250 g / cm ² under an environment of 30 ° C.
Was added, and the erasing of the colored image after 24 hours was visually evaluated. In addition, the cotton seed oil was applied to the surface of the color-developed sample, and the color-developed image was erased after being left at 30 ° C. for 24 hours.
It was evaluated visually.

The results are shown in the table below.

[Advantages of the Invention] By using the fluorane derivative according to the present invention as a thermosensitive color-forming component, a thermosensitive recording material can be easily obtained in which the color-developed portion has extremely fastness to plasticizers, oils, organic solvents and the like.

Front page continuation (72) Inventor Kazuo Imamura 2-7-8 Koteshi-cho, Tokorozawa, Saitama Prefecture

Claims (3)

[Claims] 1. A fluoran derivative represented by the following general formula I: In the above formula, R ₁ and R ₂ may be the same or different and each represents C _1-9 alkyl, C _3-6 cycloalkyl, phenyl or alkyl (C _1-4 ) -substituted phenyl. , R ₃ and R _{4, which} may be the same or different, each represents C _1-6 alkyl or phenyl, or R ₃ and R ₄ together with the carbon atom to which they are attached. Thus, a 5- to 8-membered cycloalkane may be formed. 2. The following general formula I, [In the above formula, R ₁ and R ₂ may be the same or different, and each represent C _1-9 alkyl, C _3-6 cycloalkyl, phenyl or alkyl (C _1-4 ) -substituted phenyl. R ₃ and R _{4, which} may be the same or different, each represents C _1-6 alkyl or phenyl, or R ₃ and R ₄ are together with the carbon atom to which they are attached. And may form a 5- to 8-membered cycloalkane] in producing a fluorane derivative represented by the following general formula II: [In the above formula, R ₁ and R ₂ represent the same as defined above], and 2 mol of the compound represented by the following general formula III: [Wherein R ₃ and R ₄ have the same meanings as defined above], and the reaction is carried out with 1 mol of a ketone. 3. The following general formula I, [In the above formula, R ₁ and R ₂ may be the same or different, and each represent C _1-9 alkyl, C _3-6 cycloalkyl, phenyl or alkyl (C _1-4 ) -substituted phenyl. R ₃ and R _{4, which} may be the same or different, each represents C _1-6 alkyl or phenyl, or R ₃ and R ₄ are together with the carbon atom to which they are attached. And may form a 5- to 8-membered cycloalkane]. The heat-sensitive color-forming component for recording materials, which comprises a fluoran derivative.