JPH04312588A - Fluorane compound and color-developing recording material - Google Patents

Abstract

PURPOSE:To provide a novel fluorane compound having a greenish black color tone and useful as a color-developing dye for black color-developing recording materials having high color development sensitivity and excellent preservability of the ground skins and developed color images thereof. CONSTITUTION:A fluorane compound of formula I(n is 2, 3; R is lower alkyl), for example, 2-anilino-3-methyl-6-{N-ethyl-N-(3-phenylpropyl)} aminofluorane. The compound is produced by condensing a benzoic acid derivative of formula II with a compound of formula III(R' is H, lower alkyl) in the presence of a condensing agent such as sulfuric acid. The compound of formula II is a new compound and produced by the steps of dehydration-condensing a compound of formula IV with resorcinol; alkylating the resultant new compound of formula V; and subsequently reacting the resultant compound of formula VI with phthalic anhydride in an inert organic solvent with heating.

Description

Detailed Description of the Invention [0001] [Industrial Application Field] The present invention relates to a novel fluoran compound, a novel benzoic acid derivative and an aminophenol derivative which are intermediates for the synthesis of the fluoran compound, and a method for coloring the fluoran compound. The present invention relates to a color-forming recording material containing a color dye. [0002] [Prior Art] Color-forming dyes are colorless or almost colorless in themselves, but are based on a color-forming system consisting of a color-forming dye that develops color through the action of a color developer, and an acidic substance that is a color developer that develops the color. Recording materials are widely used today as pressure-sensitive copying paper, heat-sensitive recording paper, and the like. In particular, various fluoran compounds are used as black coloring dyes. Color-forming recording materials are required to have high color-forming sensitivity, low background staining, and excellent preservation of colored images and backgrounds, but known color-forming dyes fully satisfy all of these properties. There is nothing. Further, as a black coloring dye, pure black to greenish-black is preferred, but the coloring tone of generally known fluorans is reddish black. Therefore, a method has been adopted in which a green dye is mixed in order to obtain a desired color tone. Under these circumstances, various new color-forming dyes are being studied. As a known black-coloring dye and a fluoran compound similar to the present invention, the following compounds are known, which are described in JP-A-52-273, JP-A-61-204275, and the like. ##STR4## (In the formula, R represents a lower alkyl group.) [Problem to be Solved by the Invention] The above-mentioned recording material using a fluoran compound similar to the present invention as a color-forming dye has a color-forming property. It does not fully satisfy the characteristics as a recording material, and is particularly poor in storage stability of the background. An object of the present invention is to provide a black color-forming recording material with high color development sensitivity and excellent storage stability of the background and color images, and a novel fluoran compound having a greenish-black color tone as its main component. . [Means for Solving the Problems] The present invention provides the following general formula (
Concerning the novel fluoran compound represented by I) and the black color-forming recording material containing the compound as a color-forming dye, embedded image (wherein R represents a lower alkyl group and n represents 2 or 3). ) Also, new benzoic acid derivatives represented by general formula (II) and general formula (I) which are synthetic intermediates of the fluoran compound
The present invention relates to a novel aminophenol derivative represented by II). embedded image (n and R are the same as above.) The fluoran compound of the present invention can be produced in the same manner as known fluoran compounds similar to the present invention. That is, it can be produced according to the following reaction formula using a condensing agent such as sulfuric acid. (In the formula, n and R are the same as above, and R' represents a hydrogen atom or a lower alkyl group.) Among the fluoran compounds represented by the general formula (I), particularly preferred compounds are R is an alkyl group having 1 to 3 carbon atoms. It is known that fluoran compounds have crystal modifications having different melting points, and the general formula (I) of the present invention also includes crystal modifications. These crystal modifications can be produced by selection of the recrystallization solvent of the reaction product. As a typical example, a low melting point substance is obtained when recrystallized with a nonpolar solvent such as toluene, and a high melting point substance is obtained when heating under reflux with a polar solvent such as isopropanol or butanol. In this recrystallization treatment, it is not necessary to completely dissolve the product, and it is sufficient to simply heat it in a solvent. Although the benzoic acid derivative represented by the general formula (II), which is the starting compound shown in the reaction formula, is a new compound, it can be synthesized by a conventional method according to the following reaction formula. [Formula 8] (In the formula, X represents a halogen atom, and n and R are the same as above.) That is, the compound represented by formula (V) and resorcinol are mixed in a high boiling point inert organic solvent such as pseudocumene. The compound represented by formula (VI) and m-aminophenol are heated in the presence of a Lewis acid such as zinc chloride for dehydration condensation, or the compound represented by formula (VI) and m-aminophenol are inactivated in the presence of an alkali such as sodium carbonate. By heating and reacting in an organic solvent,
A novel aminophenol derivative represented by formula (III) is obtained. Next, the compound represented by formula (IV) obtained by alkylating this compound with an alkylating agent such as alkyl iodide and phthalic anhydride are heated in an inert organic solvent to form the compound represented by general formula (II). The benzoic acid derivative represented is obtained. Specific examples of the benzoic acid derivative represented by the general formula (II) include the following compounds. 2-
{4-(N-methyl-N-phenethyl)amino-2-hydroxy}benzoylbenzoic acid (melting point 185-187
°C), 2-{4-(N-ethyl-N-phenethyl)
Amino-2-hydroxy}benzoylbenzoic acid (melting point 167-170°C), 2-{4-(N-propyl-
N-phenethyl)amino-2-hydroxy}benzoylbenzoic acid (melting point 90-95°C), 2-{4-(N-
Butyl-N-phenethyl)amino-2-hydroxy}benzoylbenzoic acid, 2-{4-(N-isobutyl-N-
phenethyl)amino-2-hydroxy}benzoylbenzoic acid, 2-{4-(N-pentyl-N-phenethyl)amino-2-hydroxy}benzoylbenzoic acid, 2-{4
-(N-hexyl-N-phenethyl)amino-2-hydroxy}benzoylbenzoic acid, 2-[4-{N-methyl-N-(3-phenylpropyl)}amino-2-hydroxy]benzoylbenzoic acid, 2 -[4-{N-ethyl-
N-(3-phenylpropyl)}amino-2-hydroxy]benzoylbenzoic acid (melting point 166-168°C)
, 2-[4-{N-propyl-N-(3-phenylpropyl)}amino-2-hydroxy]benzoylbenzoic acid The color-forming recording material containing the fluoran compound of the present invention is a pressure-sensitive copying paper. , thermal recording paper, thermal transfer recording paper, electrically conductive thermal recording paper, electrophotography that uses toner containing acidic substances as a developer, ultrasonic recording paper, photosensitive printing materials, electron beam recording paper, and stamping materials. , stamp ink, typewriter ribbon, etc., but are not limited to these. The method for producing thermal recording paper using the fluoran compound of the present invention is the same as that for known color-forming dyes. It can be produced by applying a suspension in an aqueous solution of 1 to a support such as paper and drying it. The mixing ratio of the dye and color developer can be changed as appropriate depending on the type of each dye, but it is usually 1 to 10 parts by weight, preferably 2 to 5 parts by weight, of the color developer to 1 part by weight of the dye. It is. The above suspension requires sensitizers, fillers, dispersants, color image stabilizers, antioxidants, desensitizers, antiblocking agents, antifoaming agents, light stabilizers, optical brighteners, etc. It can be contained according to the requirements. At this time, the color developer used is, for example, bisphenol A, 4,4'-sec-butylidene bisphenol, 4,4'-cyclohexylidene bisphenol, 2,2'-dihydroxydiphenyl, pentamethylene- Bisphenol compounds such as bis(4-hydroxybenzoate), sulfur-containing bisphenol compounds such as 1,7-di(4-hydroxyphenylthio)-3,5-dioxaheptane, benzyl 4-hydroxybenzoate, 4-
Ethyl hydroxybenzoate, propyl 4-hydroxybenzoate, isopropyl 4-hydroxybenzoate, butyl 4-hydroxybenzoate, isobutyl 4-hydroxybenzoate, chlorobenzyl 4-hydroxybenzoate, 4-
4-hydroxybenzoic acid esters such as methylbenzyl hydroxybenzoate and diphenylmethyl 4-hydroxybenzoate, metal salts of benzoic acid such as zinc benzoate and zinc 4-nitrobenzoate, 4-hydroxy-4'-methyldiphenylsulfone , hydroxysulfones such as 4-hydroxy-4'-isopropoxydiphenylsulfone, 4-hydroxy-4'-butoxydiphenylsulfone, dimethyl 4-hydroxyphthalate, dicyclohexyl 4-hydroxyphthalate, diphenyl 4-hydroxyphthalate, etc. 4-hydroxyphthalic acid diesters, hydroxynaphthoic acid esters such as 2-hydroxy-6-carboxynaphthalene, hydroxyacetophenone, p-phenylphenol, benzyl 4-hydroxyphenylacetate, p-benzylphenol, hydroquinone Examples include monobenzyl ether and tribromomethylsulfones such as tribromomethylphenylsulfone. Examples of sensitizers include higher fatty acid amides,
Benzamide, stearanilide, acetoacetanilide, thioacetanilide, dibenzyl oxalate, dimethyl phthalate, dibenzyl terephthalate, dibenzyl isophthalate, bis(tert-butylphenol),
Diethers of 4,4'-dihydroxydiphenylsulfone, 1,2-bis(phenoxy)ethane, 1,2-bis(4-methylphenoxy)ethane, 1,2-bis(3
-methylphenoxy)ethane, 2-naphtholbenzyl ether, diphenylamine, carbazole, 2,3-
Di-m-tolylbutane, 4-benzylbiphenyl, 4
, 4'-dimethylbiphenyl, m-terphenyl, di-
Examples include β-naphthylphenylenediamine. Examples of fillers include clay, talc, kaolin, satin white, titanium oxide, calcium carbonate, magnesium carbonate, barium sulfate, magnesium silicate, and aluminum silicate. Dispersants include sulfosuccinic acid esters such as dioctyl sodium sulfosuccinate, sodium dodecylbenzenesulfonate, sodium salts of lauryl alcohol sulfate, fatty acid salts, etc., and color image stabilizers include salicylic acid derivatives and oxynaphthoic acid derivatives. metal salts (especially zinc salts), other water-insoluble zinc compounds, etc., and 2,2'-methylenebis(4-methyl-6-t) as antioxidants.
ert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4
,4'-propylmethylenebis(3-methyl-6-te
rt-butylphenol), 4,4'-thiobis(2-
tert-butyl-5-methylphenol), etc., aliphatic higher alcohols, polyethylene glycol, guanidine derivatives, etc. as desensitizers, stearic acid, zinc stearate, calcium stearate, carnauba wax, etc. as anti-blocking agents. Examples include paraffin wax and ester wax. Pressure-sensitive copying paper using the fluoran compound of the present invention as a color-forming dye can be produced in the same manner as in the case of known color-forming dyes such as fluoran compounds. For example, the compound of the present invention microencapsulated by a known method is dispersed with a suitable dispersant and applied to paper to prepare a color former sheet. Further, a color developer sheet is prepared by applying a color developer dispersion onto paper. Pressure-sensitive copying paper is produced by combining both sheets produced in this manner. Pressure-sensitive copying paper consists of an upper paper coated with microcapsules containing a color-forming dye in an organic solvent and a color developer (acidic substance).
It may be a unit consisting of a lower paper having a color developer coated on the upper surface thereof, or a so-called self-content paper in which microcapsules and a color developer are coated on the same paper surface. Conventionally known color developers are used in this case, such as acid clay, activated clay, attabulgite, bentonite, colloidal silica, aluminum silicate, magnesium silicate, zinc silicate, tin silicate,
Calcined kaolin, inorganic acidic substances such as talc, aliphatic carboxylic acids such as oxalic acid, maleic acid, tartaric acid, citric acid, succinic acid, stearic acid, benzoic acid, p-tert-butylbenzoic acid, phthalic acid, gallic acid, salicylic acid , 3-isopropylsalicylic acid, 3-phenylsalicylic acid, 3-cyclohexylsalicylic acid, 3,5-di-tert-butylsalicylic acid, 3-methyl-5-benzylsalicylic acid,
Aromatic carboxylic acids such as 3-phenyl-5-(2,2-dimethylbenzyl)salicylic acid, 3,5-di-(2-methylbenzyl)salicylic acid, 2-hydroxy-1-benzyl-3-naphthoic acid, etc. Zinc aromatic carboxylic acid,
Metal salts such as magnesium, aluminum, titanium, p-
Phenol resin color developer such as phenylphenol-formalin resin, p-butylphenol-acetylene resin,
Examples include mixtures of these phenolic resin color developers and the metal salts of the aromatic carboxylic acids. EXAMPLES Hereinafter, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited thereto. Example 1. (1) Synthesis of N-phenethyl-m-aminophenol [Compound A - compound of general formula (III)] 700 ml of pseudocumene, 170 g of resorcinol, and 7 g of dry zinc chloride were placed in a flask and heated to 170°C to 175°C. Phenethylamine 2 was added to the flask while performing azeotropic dehydration.
00g was added dropwise. After the dropwise addition was completed, the mixture was heated under reflux for 3 hours. After the reaction, wash with 400ml of 2N sulfuric acid, and further wash with warm water for 2 hours.
Washed twice. When the oil obtained by distilling off the pseudocumene was allowed to cool, 240 g of crystals of Compound A were obtained (melting point: 66-69°C). (2) Synthesis of N-methyl-N-phenethyl-m-aminophenol [compound B - compound of general formula (IV)]) 20 g of compound A, 70 ml of isopropanol, and 12 g of sodium carbonate were charged into a flask, and 1 methyl iodide was added to the flask.
8 g was added, and the mixture was heated under reflux for 4 hours. The isopropanol was distilled off and washed with water to obtain 17 g of oily compound B. (3) 2-{4-(N-methyl-N-phenethyl)amino-2-hydroxy}benzoylbenzoic acid [Compound C-
12 g of the synthetic compound B (compound of general formula (II)) and 50 ml of toluene were placed in a flask, 10 g of phthalic anhydride was added thereto, and the mixture was heated under reflux for 4 hours. After the reaction, 100 ml of toluene was added to the reaction solution, washed twice with hot water, and the toluene layer was cooled to give 20 g of crystals of compound C.
(melting point 185-187°C). (4) 2-anilino-3-methyl-6-(N-methyl-
Synthesis of N-phenethyl)aminofluorane [Compound 1 - compound of general formula (I)] 20 g of compound C in 100 ml of ice-cooled concentrated sulfuric acid (98%)
was dissolved. After slowly adding 9.5 g of 4-methoxy-2-methyl-diphenylamine to this under ice cooling,
The reaction was carried out at ℃ for 16 hours. Pour this sulfuric acid solution into ice water,
The precipitated crystals were separated by filtration and washed with water. After neutralizing this with a 1N aqueous sodium hydroxide solution, 300 ml of toluene and 100 ml of a 10% aqueous sodium hydroxide solution were added, and the mixture was heated under reflux for 2 hours. The reaction solution was separated and the toluene layer was washed twice with hot water. After adding a small amount of activated carbon and activated clay and heating, the mixture was filtered and toluene was distilled off to obtain an oily substance. The solidified product obtained by cooling this oil was recrystallized from toluene to obtain 9.9 g of pale yellow crystals of Compound 1 (melting point 165-166.
5℃). The absorption wave number of C=O in the infrared absorption spectrum was 1740 cm-1. Example 2. In Example 1, instead of recrystallizing the final reaction product in toluene, the final reaction product was heated under reflux for 3 hours in isopropanol, and the other conditions were the same as in Example 1. 12.0 g (crystal modification different from 1) (melting point 173-175° C.) were obtained. The absorption wave number of C=O in the infrared absorption spectrum is 1
It was 759 cm-1. Example 3. 300 mg of Compound 1 having a melting point of 165 to 166.5°C obtained from the recrystallization of Example 1 was heated under reflux for 1 hour in 20 ml of isopropyl alcohol to obtain crystals. The melting point of this crystal is 173-175°C, and the absorption wave number of C=O in the infrared absorption spectrum is 1759.
cm-1. Example 4. (1) Synthesis of N-(3-phenylpropyl)-m-aminophenol [Compound D - compound of general formula (III)] 66 g of m-aminophenol in 500 ml of toluene,
66 g of sodium carbonate and 100 g of 3-phenyl-1-bromopropane were added, and the mixture was heated under reflux for 4 hours. After the reaction, add 300ml of ethyl acetate and heat for 30 minutes, then dilute with warm water for 2 hours.
It was washed twice and separated. The organic solvent was distilled off, the residue was recrystallized from toluene, and 60 g of compound D (melting point 106-109
°C) was obtained. (2) N-ethyl-N-(3-phenylpropyl)-m
Synthesis of -Aminophenol [Compound E - compound of general formula (IV)] 22 g of Compound D, 11 g of sodium carbonate, and 18 g of ethyl iodide were added to 100 ml of isopropanol, and the mixture was heated under reflux for 10 hours. After the reaction, the solvent was distilled off and washed with water to obtain 20 g of Compound E. (3) Synthesis of 2-[4-{N-ethyl-N-(3-phenylpropyl)}amino-2-hydroxy]benzoylbenzoic acid (compound F - compound of general formula (II)) Compound E 25.5 g was dissolved in 50 ml of toluene, 16 g of phthalic anhydride was added thereto, and the mixture was heated under reflux for 4 hours. After the reaction, 100 ml of toluene was added and washed with hot water three times, and the toluene layer was cooled to obtain 24 g of crystals of compound F (melting point 166).
~168°C). (4) 2-anilino-3-methyl-6-{N-ethyl-
Synthesis of N-(3-phenylpropyl)}aminofluorane [Compound 9 - compound of general formula (I)]) After dissolving 12 g of compound F in 50 ml of concentrated sulfuric acid (95%) under ice cooling,
4-methoxy-2-methyl-diphenylamine 6.5g
was added and reacted at 0°C for 15 hours. This sulfuric acid solution was poured into ice water, and the precipitated crystals were separated by filtration and washed with water. To this, 1 toluene
After neutralizing with 1N aqueous sodium hydroxide solution, 30ml of 10% aqueous sodium hydroxide solution was added, and 2
The mixture was heated to reflux for an hour. After separating the reaction solution and washing the toluene layer with hot water, the toluene was distilled off to obtain crude crystals of the target product. This was recrystallized from butanol to obtain 9 g of crystals of Compound 9 (melting point: 167-170°C). Below, general formula (I) synthesized in the same manner
Representative examples of the fluoran compounds of the present invention represented by are shown in Table 1. Example 5. (Thermosensitive recording paper) Glass beads (diameter 1 to 1
．． 5 mm) in a polyethylene bottle, the bottle was sealed tightly, and the mixture was ground in a paint conditioner for several hours to prepare a dye suspension and a color developer suspension. Dye suspension/compound of general formula (I)
3.5g clay
15.0g/15% polyvinyl alcohol aqueous solution 41.5g/water
40.0g color developer suspension/bisphenol A
10.5g clay
8.0g/15% polyvinyl alcohol aqueous solution 41.5g/water
40.0g
A coating solution prepared by mixing both suspensions at a ratio of 1:1 was applied to white base paper and dried to produce heat-sensitive recording paper. As a comparative example, the following fluoran compound similar to the compound of the present invention (comparative compound) was used instead of the compound of general formula (I).
A thermosensitive recording paper was similarly produced using the following. Test Example 1 The thermosensitive recording paper produced in Example 2 was tested in a dry heat tester (
(manufactured by Kishino Kagaku Kikai Co., Ltd.) was heated on both sides at a temperature of 150 °C to color a part of the thermal recording paper.
All of the thermal recording papers using the compounds of the present invention exhibited clear black coloring and had little background staining. In addition, as a preservability test for colored images and background parts, a moist heat resistance test (5
(Leave for 24 hours in an atmosphere of 0°C and 80% relative humidity)
When a light fastness test (10 hours of exposure to sunlight) was conducted, there was little background coloration and little discoloration of the image. Macbeth reflection densitometer (model RD-514, Wratten #
The results of the skin preservation test measured by 106) were
Shown in the table. [0019]
Table 2 Compound No. Before the test After the test

Humid heat resistance test Light resistance test 1 0
．． 10 0.15
0.19 2
0.07 0
．． 08 0.16
3 0.09
0.07 0.17
4 0.07
0.07
0.22 5
0.10 0.10
0.22 6
0.10
0.10 0.22
7 0.10
0.13 0.26
8 0.
12 0.10
0.15 9
0.12 0.
12 0.15
10 0.07
0.08 0.12
Comparison 0.10
0.10 0.3
1 Here, compound No. 1 was synthesized in Example 1. Test Example 2. The thermal recording paper produced in Example 5 was colored using a thermal paper test coloring device (Model TH-PMD, manufactured by Okura Electric Co., Ltd.) at a printing voltage of 22 V while changing the pulse width, and the color density was determined by Macbeth reflection. When measured with a densitometer (model RD-514, Wratten #106), all of the thermal recording papers of the present invention had higher sensitivity than thermal recording papers using comparative compounds. Effects of the Invention The color-forming recording material containing the fluoran compound of the present invention as a color-forming dye has superior properties as a recording material compared to known color-forming recording materials made of similar fluoran compounds. In particular, the storage stability of the skin was excellent.

Claims (4)

[Claims] [Claim 1] A fluoran compound represented by general formula (I). [Formula 1] (In the formula, n represents 2 or 3, and R represents a lower alkyl group.) 2. A color-forming recording material containing the compound according to claim 1 as a color-forming dye that develops color by the action of a color developer. 3. A benzoic acid derivative represented by general formula (II). [Formula 2] (In the formula, n represents 2 or 3, and R represents a lower alkyl group.) 4. An aminophenol derivative represented by the general formula (III). [Chemical formula 3] (In the formula, n represents 2 or 3.)