JPS59176353A - Novel fluoran derivative and thermal recording material - Google Patents

Abstract

NEW MATERIAL:Fluoran derivatives of formula I wherein R<1>, R<2> are each a 1- 4C lower alkyl. EXAMPLE:2-(4-Acetylphenyl)amino-6-N-methyl-N-4'-n-butylphenylaminofluo ran. USE:They are used as a heat-sensitive color coupling component for leuco thermal recording materials and gives thermal recording materials which exhibits little ground color formation, has a high color density and a low initial color forming temp. and is excellent in initial rise of color formation. PREPARATION:A diphenylamine compd. of formula II (wherein R is H, lower alkyl) is reacted with a benzophenone compd. in the presence of a condensing agent such as conc. sulfuric acid. The reaction product is separated and purified by filtration, extraction, recrystallization, etc. to obtain the fluoran derivative of formula I .

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field 1] The present invention relates to a novel fluorane derivative and a leuco-based heat-sensitive recording material using the same as a heat-sensitive coloring component.

[Prior art]

Fluoran compounds are used as color-forming components in leuco-based heat-sensitive recording materials, and are also used as color-forming dyes in pressure-sensitive recording paper, current-carrying recording paper, and heat-sensitive multiplex paper. Among various fluoran compounds, fluoran compounds having a (substituted phenyl)amine group at the 2-position are disclosed in Japanese Patent Publication No. 48-2406, Japanese Patent Publication No. 48-43296, Japanese Patent Publication No. 49-32767, and Japanese Patent Publication No. 51-23204.
No. and Japanese Patent Application Laid-open No. 49-34526-1989, etc., and known substituents include an alkyl group, an alkoxy group, a halogen atom, and a cardaki 7 group. The fluoran compounds disclosed in these publications are used as dye precursors for recording feeds such as heat-sensitive recording paper, current-carrying recording paper, and pressure-sensitive recording paper. However, thermal recording papers using these fluoran compounds as dye precursors have drawbacks such as color density, ground color density, color onset temperature, and color rise, and cannot exhibit sufficient performance as thermal recording paper. I can't.

For example, 2-anilino-3-methyl-6-)ethylaminofluorane disclosed in the above-mentioned publication has the disadvantage that it partially develops color during the production of thermal recording paper, increasing the background color density of the thermal recording paper. Also, thermal recording paper d1 using 2-(2-chlorophenyl)amino/-6-):f-thi) and 7minofluorane develops color (although the degree of love is low, the starting density of color development is too high. However, the rise and rise of the color development was also insufficient, and the color development of 2-anilino-3-methyl-6-N-methyl-N-7chlorohexyl7'minofluorane was insufficient. .

〔the purpose〕

The present inventors aimed to overcome the drawbacks of the known full-color derivatives, and in particular, to create a material that has almost no ground coloring, a high color density, a low color initiation temperature, and a low color development temperature. The object of the present invention is to provide a fluoran derivative having excellent rise properties and to provide a leuco thermosensitive recording medium containing the fulmeran derivative.

〔composition〕

According to the present invention, (1) a fluoran derivative represented by the general formula (wherein R1 and 2 represent a lower alkyl group having 1 to 4 carbon atoms); and (2) a fluoran derivative represented by the general formula (1) above; A leuco thermosensitive recording material is provided, which is characterized in that the fluorane derivative shown above is used as a thermosensitive coloring component.

The fluorane derivative 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 black pigment when it comes into contact with an acidic substance, and this colored pigment Because it has excellent storage stability, it has sufficient utility as a dye precursor.

The fluoran derivative represented by the above general formula (I) of the present invention is produced by the following method (5) or (B).

(5) A diphenylamine compound represented by the general formula (wherein R is a hydrogen atom or a lower argyl group) and a diphenylamine compound represented by the general formula (wherein 1 and 2 are as defined in general formula (1)). (which have the same meaning) are reacted for several hours to several tens of hours at a temperature of 0 to 100° C. in the presence of a condensing agent such as concentrated sulfuric acid. After the reaction, the reaction mixture is added to ice water and the precipitate is collected by filtration. Add a 1-20% aqueous sodium hydroxide solution to the cake, stir at 0-100°C for several hours, add toluene, and stir for 1-2 hours. Next, the toluene layer is separated, washed with water and concentrated, and the precipitated crystals are collected by filtration. Then, by recrystallizing with a volatile organic inert solvent such as toluene, benzene, methyl ethyl ketone, acetone, etc., a highly pure fluoran derivative represented by the general formula (f) is obtained.

(13) A fluoran compound having an amine group at the 2-position represented by the general formula (wherein 1 and 2 have the same meanings as defined in the general formula (1)) and acetyl M By reacting chlorobenzene with potassium carbonate, copper powder, and iodine in a volatile organic inert solvent using iodine as a catalyst, a fluoran derivative represented by the general formula (1) is produced. From the viewpoint of production, the method (5) above is more preferable.

Condensing agents used in the present invention include concentrated sulfuric acid, fuming sulfuric acid, acetic anhydride, phosphoric acid, and boronic acid. be.

Another aspect of the present invention is a leuco-based heat-sensitive recording material containing at least one fluoran derivative represented by the above general formula (1) as a heat-sensitive coloring component. A leuco-based heat-sensitive recording material using the fluorane derivative can be produced according to a conventionally known method.

That is, the fluoran derivative according to the present invention and a lake coloring agent (for example, a phenolic compound or other electron-accepting substance) are coated on a support such as paper, Norasutisoku film, cloth, etc. in a single layer or in multiple layers using a binder. A heat-sensitive coloring layer may be formed by drying. In addition, in order to improve the whitening effect and writability, this heat-sensitive coloring layer contains 0a003 and T.
Inorganic fillers such as i'02, ZnO, talc, clay, kaolin, and other organic fillers, as well as any auxiliary additive components commonly used in this field, may be added.

The leuco-based heat-sensitive recording material of the present invention can have various structures, and those with conventional structures that utilize a color-forming reaction between a leuco dye and a color developer include all-C. Ru. For example, the leuco-based heat-sensitive recording material of the present invention includes a heat-sensitive recording material having a structure in which a leuco dye and a color developer are supported on a support as the same coating layer or separate coating layers, and a leuco dye in a transfer layer. A transfer sheet formed by supporting a support as a color developer, and a receiver sheet formed by supporting a support with a color developer as a receptor layer!・It can be used as a thermal transfer type heat-sensitive recording material consisting of. In the case of thermal transfer type thermal recording materials,
The receptor sheet is stacked on the transfer sheet so that the receptor layer is in contact with the transfer layer of the transfer sheet, and the polymerized sheet is thermally printed from the front or back side to form the desired image on the receptor layer surface of the receptor sheet. A colored image can be formed.

The leuco-based heat-sensitive recording material of the present invention is used in various recording fields, particularly as a heat-sensitive recording material for high-speed recording that requires high image stability.

〔effect〕

The fluorane derivative represented by the general formula (1) according to the present invention is itself a colorless or slightly colored solid that is stable in the atmosphere, and immediately forms a black pigment when it comes into contact with an acidic substance, and this colored pigment In addition to having excellent storage stability, the leuco-based thermosensitive recording A'A material containing the fluoran N%i conductor has almost no ground coloring, high coloring density, and a low coloring start temperature. It is low and has excellent color development. In addition to heat-sensitive recording materials, the fulloleolane diluent of the present invention can also be used as a color-forming dye in pressure-sensitive recording paper and electromagnetic recording paper.

〔Example〕

Next, the present invention will be explained in more detail with reference to Examples.

Example 1 Synthesis of 2-(4-acetylphenyl)amino-6-N-methyl r N -4'-〇-butylphenylaminofluorane 2-(4-(N-methyl-N
-4-n-butylphenyl)amino-2-hydroxybenzoyl]penzoitsqua/so122.2 +i'
(!: 12.17 g of 4-methoxydi-4-acetyldiphenylamine was added and reacted for 50 hours at a temperature of 20-25°C. After the reaction, the reaction mixture was added to 500 ml of ice water, and the precipitate was filtered off. Add 500 ml of 5% thorium hydroxide aqueous solution to the cake and stir for 1 hour, then add 1000 ml of toluene and stir for 2 hours.Then, separate the toluene layer, wash with water, and dilute with anhydrous sulfuric acid.l) Dehydrate with ram. After that, the toluene is concentrated and crystallized from methyl ethyl ketone to give an almost white color with a melting point of 152.5 to 15.
2-(4-acetylphenyl)amino-6-N- at 4°C
12.5 g of methyl-N-4'-n-butylphenylaminofluorane were obtained.

The elemental analysis values of this fluoran compound are as shown in Table 1, and they matched within the error range.

Table-1 Example 2 2-(4-7cetylphenyl)ami/-6-N-ethyl 7
2-[4-(N-methyl-N-4-tolyl)amino-2 in 100 d of 4'-tolylaminofluorane 95% sulfuric acid
-Hydroxy/benzoyl]benzoic acid 20
．． 69 and 4-methoxy-47-acetyldiphenylamine 12.17 By adding gold and reacting and treating in the same manner as in Example 1, a pale yellow-white color with a melting point of 267 and a temperature of 2 to 270°C was obtained.
15.39 of 2-(4-acetylphenyl)amino-6-N-methyl-N-4'-tolylaminofluorane was obtained and water.

The elemental analysis values of this fluoran compound are shown in Table 2, and they matched within the error range.

Next, Table 3 summarizes the maximum absorption wavelengths and hues of colors developed on bisphenol A and silica gel thin layers for the various fluoran compounds obtained as described above.

Below is a margin Example 3 (Production of leuco-based thermosensitive recording moon phase) Composition of liquid A 10% aqueous solution of hydroquine ethyl cellulose 1 oy water
3o
B liquid composition 2.2-bis(p-hy+y-oxyphenyl)pro 1
10% ykJ solution of 0f-hydroquine ethylcellulose 1ay water 3
Or the above canned liquid in separate magnetic numbers? - After being dispersed in Lumil for 2 days, liquid A and liquid B were mixed at a ratio of 1:3 (weight ratio), and a 20% aqueous solution of oxidized starch was added to this so that the dry weight ratio was as shown in Table 4 below. The components were added and mixed to prepare a thermosensitive coloring layer forming solution.

Below is a margin table-4. Next, apply this heat-sensitive coloring layer forming liquid to
Apply it to one side of high-quality paper using a wire spar so that the dry adhesion amount is approximately 2 y 7 m2, and dry it to form a layer of heat-sensitive recording paper (
Make sample A)/B.

For comparison, 2-(acetylphenyl) in solution A
, 2-anilino-3-methyl-6-N-methyl-N-7 chlorohexol aminofluorane was used instead of amino-6-N-methyl-N-4'-n-butylphenylaminofluorane. A comparative thermosensitive recording paper (sample B) was prepared in the same manner as Hazanpur A except that the sample B was used.

The following tests were conducted using these thermosensitive recording papers. Thermal recording paper sample A and comparative sample 13 were heated to 90°C+
The color hue, color density, and background color density were measured at a temperature of 100°C + 120°C and 150°C under a pressure of 21 (by applying a pressure of 1 second) using a Macbeth reflection densitometer rule using a type 514 black filter.

The measurement results are shown in Table 5. Sample A (product of the present invention) is overall superior to Sample B (comparative product), with particularly low background color density, color density, and color development. It was also recognized that it was significantly superior. -Table-5

Claims (3)

[Claims] (1) A fluoran derivative represented by the general formula (wherein R, I and 2 represent a lower alkyl group having 1 to 4 carbon atoms). (2) The compound represented by general formula (1) is 2-(4-
7cetylphenyl)amino-6-N・-methylN-4
The fluoran derivative according to claim 1, which is -n-butylphenylaminofluoran. (3) A leuco-based heat-sensitive recording material characterized in that a fluoran derivative represented by the general formula (wherein R1 and R2 represent a lower alkyl group having 1 to 4 carbon atoms) is used as a heat-sensitive coloring component.