GB2210626A - Indolylazaphthalide compounds used as colour formers - Google Patents

Abstract

An indolylazaphthalide compound is of the formula <IMAGE> where R1 and R2 each are alkyl or may together complete a heterocycle; R3 is H, alkyl or aryl; R4 is alkoxy; X and Y are each H, halogen, nitro, alkyl, alkoxy or amino; one of Z1 and Z2 is =N- and the other is =CH-; any alkyl, aryl, alkoxy or amino can be substituted; m is an integer of 1-4 and n is 1-3. The compounds form a bright blue colour of good light-fastness on reaction with an electron-accepting developer and so are useful as color formers alone or with other colour formers, in a sensitive layer, e.g. in solution in microcapsules, of recording material, e.g. pressure- or heat-sensitive material.

Description

INDOLYLAZAPHTHALIDE COMPOUNDS USED AS COLOR FORMERS This invention relates to an indolylazaphthalide compound useful as a color former in pressure-sensitive, heat-sensitive, light and pressuresensitive, conductive heat-sensitive and heatsensitive transfer recording materials.

Indolylazaphthalide compounds are described in detail, e.g., in JP-B-51-16807 (corresponding to U.S. Patent 3,775,424) and JP-B-61-4856 (corresponding to U.S. Patent 4,675,407) (the term "JP-B" as used herein means an "examined published Japanese patent application"). As a result of investigations, the present inventors have established that the hue of the colors developed by indolylazaphthalide compounds varies greatly depending on the kind of substituents of these compounds or the kind of a developer used in combination therewith. For example, 3-(4 diethylamino-2-ethoxyphenyl) -3- (I-n-octyl-2- methylindol-3-yl)-4-azaphthalide develops a blue color on reaction with a phenolic resin but develops a cyan color on reaction with a salicylic acid developer.

Crystal Violet lactone is known as a color former which develops a bright blue color on reaction with a salicylic acid developer, but its color image is very poor in light-fastness. Therefore, there has been a need to develop a color former for blue color developing recording materials which develops a bright blue color having satisfactory light-fastness.

One object of this invention is to provide a color former which develops a bright blue color having satisfactory light-fastness on reaction with a developer and recording material produced therefrom.

As a result of extensive investigations, the present inventors succeeded in obtaining an indolylazaphthalide compound which develops a bright blue color having satisfactory light-fastness on reaction with a salicylic acid developer by bonding of a hydrogen atom to the 2-position of the indole ring.

Thus, as a result of studies on various substituents of indolylazaphthalide compounds, it has now been found that the above object can be accomplished by an indolylazaphthalide compound represented by formula (I)

wherein R1 and R2 each represents a substituted or unsubstituted alkyl group, and R1 and R2 may combine with each other to form a 5- to 8-membered heterocyclic ring; R3 represents a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group; R4 represents a substituted or unsubstituted alkoxy group;X and Y each represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a halogen atom, a nitro group, or a substituted or unsubstituted amino group; one of Z1 and Z2 represents a nitrogen atom and the other is ECH; m represents an integer of from 1 to 4; and n represents an integer or from 1 to 3.

In formula (I), the term "aryl group" means a phenyl group, a naphthyl group or an aromatic heterocyclic group, and the substituents therefor may be an alkyl group, an alkoxy group, an aryloxy group, a halogen atom, a nitro group, a cyano group, a substituted or unsubstituted carbamoyl group, a substituted or unsubstituted sulfamoyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted oxycarbonyl group and a substituted or unsubstituted oxysulfonyl group.

The term "alkyl group" as used in formula (I) means a saturated or unsaturated alkyl group or a cycloalkyl group, and the substituents therefor include an aryl group which is defined as above, an alkoxy group, an aryloxy group, a halogen atom, a cyano group, an acyl group, a hydroxyl group and a sulfuryl group.

R1 and R2 each preferably represents a substituted or unsubstituted alkyl group having from 1 to 18, more preferably from 2 to 12, carbon atoms, and the substituents therefor include a halogen atom, an alkoxy group, an aryl group, an aryloxy group, an alkyl group, an acyl group, a cyano group, a hydroxyl group and a furfuryl group.

The 5- to 8-membered heterocyclic ring, which may be formed by R1 and R2, includes piperidine, morpholine, pyrrolidine, piperazine, hexamethyleneimine, caprolactam and indole.

Specific examples of the atomic group

include pyrrolidino, piperazino, morpholino, N-ethylpiperidino, dimethylamino, diethylamino, dipropylamino, dibutylamino, N-ethyl-N-isobutylamino, N-ethyl-N-isoamylamino, N-ethyl-N-benzylamino, diamylamino, dihexylamino, dioctylamino, N-ethyl-Ntetrahydrofurfurylamino and dibenzylamino groups.

R3 preferably represents a hydrogen atom, a substituted or unsubstituted alkyl group having from 1 to 18 carbon atoms or a substituted or unsubstituted aryl group having from 6 to 12 carbon atoms.

The substituents for the alkyl or aryl group for R3 include a halogen atom, an alkoxy group, an aryl group, an aryloxy group, an alkyl group, an acyl group, a cyano group, a hydroxyl group and a furfuryl group.

More preferably, R3 represents a hydrogen atom, a substituted or unsubstituted alkyl group having from 2 to 12 carbon atoms or a substituted or unsubstituted aryl group having from 6 to 12 carbon atoms.

Specific examples of R3 include a hydrogen atom and methyl, ethyl, n-butyl, n-octyl, 2-ethylhexyl, n=dodecyl, n-octadecyl, benzyl, p-methylbenzyl, phenethyl, B-phenoxyethyl, ss-(4-methoxyphenoxy)ethyl, phenyl and 4-methylphenyl groups.

R4 preferably represents a substituted or unsubstituted alkoxy group having from 1 to 18 carbon atoms. The substituents for the alkoxy group for R4 include a halogen atom, an alkoxy group, an aryl group, an aryloxy group, an alkyl group, an acyl group, a cyano group, a hydroxyl group and a furfuryl group. Of these, more preferred are substituted or unsubstituted alkoxy groups having from 2 to 12 carbon atoms Specific examples of R4 include methoxy, ethoxy, propoxy, isopropoxy, n-butoxy, n-hexyloxy, n-octyloxy, 2-ethylhexyloxy, n-dodecyloxy, noctadecyloxy, benzyloxy, E-methylbenzyloxy, phenethyloxy, B-phenoxyetoxy, and S-(4-methoxyphenoxy)- ethoxy groups.

X and Y each preferably represents a hydrogen atom, a substituted or unsubstituted alkyl group having from 1 to 12 carbon atoms, a substituted or unsubstituted alkoxy group having from 1 to 12 carbon atoms, a chlorine atom, a bromine atom, a nitro group, a mono- or dialkylamino group having from 1 to 12 carbon atoms, or a monoacrylamino group having from 1 to 12 carbon atoms.

The color former according to the present invention may be used together with one or more known compounds, such as triphenylmethanephthalide series compounds, fluoran series compounds, phenotiazine series compounds, indolylphthalide series compounds, Leuco Auramine series compounds, Rhodamine lactam series compounds, triphenylmethane series compounds, triazene series compounds, spiropyran series compounds, and fluoren series compounds.

In such case, from the viewpoint of the improvement of light-fastness, the compounds of the present invention are preferably used in an amount of 40 wt% or more per the weight of the above-described compounds.

Typical examples of phthalide compounds are described in U.S. Re-issue Patent 23,024, U.S. Patents 3,491,111, 3,491,112, 3,491,116 and 3,509,174, typical examples of fluoran compounds are described in U.S.

Patents 3,624,107, 3,627,787, 3,641,011, 3,462,828, 3,681,390, 3,920,510 and 3,959,571, typical examples of spiropyran compounds are described in U.S. Patent 3,971,808, typical examples of pyridine or pyrazine compounds are described in U.S. Patents 3,775,424, 3,853,869, and 4,246,318, and typical examples of fluoran compounds are described in JP-A-63-94878 (the term JP-A" as used herein means an "unexamined published Japanese patent application").

Typical examples of salicylic acid series developers used to provide a color image in contact with the color former in the present invention are described, for example, in U.S. Patents 3,767,449, 4,219,213, 4,269,893, 4,374,671, 4,687,869, and European Patents 219,302 and 264,051.

These color formers and developers may be applied to recording material in the form of fine dispersion, microdroplet or film.

In the recording materials according to the preset.invention, various additives known in the fields of recording material or polymeric resin, such as pigment, wax, antistatic agent, ultravioletabsorbing agent, defoaming agent, conducting agent, fluorescent dye or surface active ant may be used.

The compounds according to the present invention can be applied for various forms of the pressure-sensitive recording paper as described, for example, in U.S. Patents 2,505,470, 2,505,471, 2,505,489, 2,548,366, 2,712,507, 2,730,456, 2,730,457, 3,103,404, 3,418,250, and 4,010,038. In general, the pressure-sensitive recording paper comprises at least one pair of sheets wherein an electron-donating colorless dye is coated on one sheet and an electronaccepting compound is coated on the other sheet.

Microcapsules containing the color former may be prepared by various techniques such as a coacervation of hydrophilic colloidal sol as described, for example, in U.S. Patents 2,800,457 and 2,800,458, an interfacial polymerization as described, for example, in British Patents 867,797, 950,443, 989,264 and 1,091,076, and a method described, for example, in U.S. Patent 3,103,404.

Further, the compounds according to the present invention can be applied to a heat-sensitive recording paper as described, for example, in JP-A62-144,989, a conductive heat-sensitive recording paper as described, for example, in JP-A-49-11344 and JP-A-50-48930, and a light and pressure-sensitive recording paper as described, for example, in JP-A-57-179836.

The present invention is now illustrated in greater detail with reference to the following Examples, but it should be understood that the present invention is not deemed to the limited thereto.

EXAMPLE 1 3-(4-Diethylamino-2-Ethoxyphenyl)-3-(1-n-Octylindol- 3-yl)-4-Azaphthalide: In a flask equipped with a stirrer were -charged 0.2 mol of quinolic anhydride, 0.2 mol of l-n-octyl-indole, 100 ml of acetic acid, and 0.03 mol of zinc chloride, and the mixture was stirred at 300C for 8 hours. To the mixture were added 0.2 mol of N,N-diethyl-m-phenetidine and 40 ml of acetic anhydride, followed by stirring at 600C for 3 hours.

The reaction mixture was poured into water and made alkaline with a sodium hydroxide aqueous solution.

The reaction mixture was subjected to column chromatography using a 3:1 (by volume) mixture of n-hexane and ethyl acetate as an eluent to obtain the entitled compound as a white crystal having a melting point between 111 to 1120C.

EXAMPLES 2 TO 13 Compounds shown in Table 1 below were prepared in the same manner as described in Example 1, but starting with the corresponding materials. In Table 1, X indicates a hue developed on a paper max support coated with zinc 3,5-bis(a-methylbenzyl)salicylate.

TABLE 1 Example No. R1 R2 R3 R4 X Y Z1 Z2 #max (nm)

2 C2H5 C2R5 nC8H17 OCR H H N CR 585 co oo H rn rr, u, m CD In 585 4 CR5 C2R5 nC4H9 -0-CR H H N CR 590 Z Z Z Z Z Z Z Z Z Z Z Z 6 CR CR 4CH2)2- OC2H5 H H N CR 586 7 C2H5 CR5 -O4CH2)2O OC2R5 H H N CR 587 8 CR3 CR3 nC8H17 OC2R5 H H N CH 585 CC &commat; v T = hl I 10 CR3 CJ -CR O ro) H H I CR 586 O nC4 H9 O CR5 O-n-C4H9 H H N CR 585 12 nC8H17 nC8H17 H OC2R5 H H N CR 584 ri nC8R17 OC2H5 H H m r 586 U o U u U N c) O CE r1 m c S N cs N ; an H EXAMPLE 14 3-(4-Diethylamino-2-Ethoxyphenyl)-3-(1-n-Octylindol3-yl)-7-Azaphthalide:: In a flask equipped with a stirrer were charged 0.12 mol of quinolic anhydride, 0.1 mol of l-n-octyl-indole, 200 ml of ethylene chloride, and the mixture was cooled to an internal temperature of 30C with stirring. To the mixture were gradually added 0.36 mol of zinc chloride anhydride, followed by stirring at 40"C for 5 hours. The reaction mixture was poured into dilute hydrochloric acid and repeatedly washed with water for several times to concentrate the organic layer.

To the concentrated residue was added 0.1 mol of N,N-diethyl-m-phenetidine and 20 ml of acetic anhydride, followed by stirring at 600C for 2 hours.

The reaction mixture was poured into water and made alkaline with an aqueous sodium hydroxide solution.

The reaction mixture was subjected to column chromatography using a 3:1 (by volume) mixture of nhexane and ethyl acetate as an eluent to obtain the entitled compound as a white crystal having a melting point between 109 to 1100C.

The pressure-sensitive recording paper of the present invention can be produced by the procedures as shown in the following Examples 15 and 16, but it should be understood that the present invention is not deemed to be limited thereto.

Unless otherwise specified, all "%"' are by weight.

(1) Preparation of sheet coated with microcapsules containing an electron-donating colorless dye Five parts of a partial sodium salt of polyvinylbenzensulfonic acid (manufactured by National Starch Co., trade name "VERSA TL500") was dissolved into 95 parts of hot water and then cooled.

The pH of the solution was adjusted to 4.0 by adding an aqueous sodium hydroxide solution.

In the next step, 100 parts of diisopropylnaphthalene having 3.58 of electron-donating colorless dye dissolved therein was dispersed in 100 parts of the 5% aqueous solution of partial sodium salt of polyvinylbenzen sulfonic acid to obtain an emulsion having an average particle size of 4.0 pm.

In a separate step, a mixture of 6 parts of melamine, 11 parts of a 37 wt% aqueous solution of formaldehyde and 30 parts of water was stirred at 600C for 30 minutes to obtain a transparent aqueous solution of melamineformaldehyde initial condensation product.

The resulting aqueous solution was mixed with the above emulsion. The pH of the mixture was adjusted to 6.0 by adding a 2 M phosphoxic acid solution with stirring. After increasing the temperature of the mixture to 650C, agitation was continued for 6 hours. The resulting capsule solution was cooled down to a room temperature, and the pH of the solution was adjusted to 9.0 by adding an aqueous sodium hydroxide solution.

To the thus prepared dispersion of capsules, 200 parts of 10 wt% aqueous solution of polyvinyl alcohol and 50 parts of starch particles were added, and the solid content of the microcapsule dispersion was adjusted to 20% by addition of water.

The thus obtained coating solution was coated on a base paper (base weight: 50 g/m2) in an amount of 5 g/m2 (on a solid bade) by means of an air-knife coater and dried to provide a sheet coated wit micapsules containing the electron-donating colorless dye.

(2) Preparation of electron-accepting compounds sheet Ten parts of zinc 3,5-bis(a-methylbenzyl)salicylate was dissolved in 20 parts of 1-isopropylphenyl-2-phenylethane. The solution was added to the mixture of 50 parts of 2% aqueous solution of polyvinyl alcohol and 0.1 parts of 10% aqueous solution of trienol amine dodecylbenzenesulfonate, and emusified to form an emulsion having an average particle size of 3 pm.

A dispersion solution obtained from 80 parts of calcium carbonate, 20 parts of zinc oxide, 1 part of sodium hexametaphosphate and 200 parts of water was mixed with the above emulsion. Then, 100 parts of 10% PVA aqueous solution and 10 parts (as a solid base) of carboxy-modified SBR latex were added as a binder into the mixture. Water then was added to obtain a coating solution (A) with a solid content of 20%.

In the next step, a mixture obtained from 10 parts of the aforesaid color developer, 20 parts of siltonclay, 60 parts of calcium carbonate, 20 parts of zinc oxide, 1 part of sodium hexametaphosphate and 200 parts of water was uniformly dispersed with a sand grinder to form a dispersion having an average particle size of 3 pm. To the resulting dispersion 16 parts of 10% PVA aqueous solution, 100 parts of 10% PVA aqueous solution and 10 parts (as a solid base) of carboxy-modified SBR latex were added.

Water then was added to obtain coating solution (B) with a solid content of 20%.

The resulting coating solutions (A) and (B) were mixed in a proportion of 1:1 (as calculated as developer). The mixture was coated on a base paper (base weight: 50 g/m2) in an amount of 5.0 g/m2 (on a solid base) by means of an air knife coater, and dried to provide a developer sheet.

The microcapsule coated surface of the color former sheet containing the electron-donating colorless dye was superposed on the coated surface of the electron-accepting compound sheet, and a load of 600 kg/m2 was applied to the superposed sheets to cause a color reaction. Consequently, all the sheets immediately developed a blue color. The thus developed color image exhibited excellent lightfastness.

EXAMPLES 15 AND 16 The color formers used in the above procedures were as below.

Example N6. Color Former Xmax (nm) Example 15 Compound 1 585 585 1 Mixture (8:2 by weight) Example 16 of Compounds of Example 585 1 and Example 14 EXAMPLE 17 A mixture of 20 g of the compound of Example 5, 20 g of zinc 4-B-p-methoxyphenoxysalicylate as an electron-accepting compound, 20 g of stearic acid amide as a heat-fusible material and 100 g of 5% aqueous solution of polyvinyl alcohol (PVA 105, manufactured by Kuraray Co., Ltd.) was dispersed by means of a ball mill for 24 hours to obtain a emulsion having an average particle size of 3 m.

In the next step, 80 g of calcinated caoline (Anisilex-93) and 160 g of 0.58 sodium hexametaphosphate solution were dispersed by means of a homogenizer.

The thus obtained dispersion was mixed with 5 g of electron-donating colorless dye dispersion, 10 g of electron-accepting compound dispersion, 5 g of stearic acid amide dispersion and 22 'g of calcinated caoline dispersion, and then 4 g of zinc stearate emulsion and 5 g of 2% aqueous solution of sodium (2-ethylhexyl)sulfosuccinate were added to the mixture to obtain a coating solution.

The resulting coating solution was coated on a high quality paper having a base weight of 50 g/m2 in an amount of 6 g/m2 (on a dry base) with a wire bar and then subjected to a calendering treatment to obtain a coating paper.

When the thus obtained coating paper was developed by means of a high sensitive facsimile FF-2000 (manufactured by Fujitu Co., Ltd.) to obtain a blue color image. The thus developed color image exhibited excellent light-fastness and heat-fastness.

COMPARATIVE EXAMPLE 1 A capsule sheet was prepared and developed in the same manner as in Example 15 except that 3-(4-diethylamino-2-ethoxyphenyl)-3-(1-n-octyl-2- methylindole-3-yl)-4-azaphthalide was used in place of the color former of Example 15.

As a result, a cyan color having a maximum absorption wavelength of 620 nm (#max 620 nm) was developed. The thus developed color image exhibited the similar light-fastness.

Claims (12)

1. An indolylazaphthalide compound represented by formula (I)

wherein R1 and R2 each represent a substituted or unsubstituted alkyl group, and wherein R1 and R2 may combine with each other to form a 5- to 8membered heterocyclic ring; R3 represents a hydrogen atom, a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group; R4 represents a substituted or unsubstituted alkoxy group; X and Y each represents a hydrogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkoxy group, a halogen atom, a nitro group, or a substituted or unsubstituted amino group; one of Z1 and Z2 represents a nitrogen atom and the other is ECH; m represents an integer of from 1 to 4; and n represents an integer of from 1 to 3.

2. An indolylazaphthalide compound as claimed in Claim 1, wherein R1 and R 2 each represents a substituted or unsubstituted alkyl group having from 1 to 18 carbon atoms.

3. An indolylazaphthalide compound as claimed in Claim 2, wherein R1 and R2 each represents a substituted or unsubstituted alkyl group having from 2 to 12 carbon atoms.

4. An indolylazaphthalide compound as claimed in Claim: 1, 2 or 3, wherein R3 represents a hydrogen atom, a substituted or unsubstituted alkyl group having from 1 to 18 carbon atoms or a substituted or unsubstituted aryl group having from 6 to 12 carbon atoms.

5. An indolylazaphthalide compound as claimed in Claim 4, wherein R 3 represents a hydrogen atom, a substituted or unsubstituted alkyl group having from 2 to 12 carbon atoms or a substituted or unsubstituted aryl group having from 6 to 12 carbon atoms.

6. An indolylazaphthalide compound as claimed in any preceding claim, wherein R 4 represents a substituted or unsubstituted alkoxy group having from 1 to 18 carbon atoms.

7. An indolylazaphthalide compound as claimed in Claim 6, wherein R 4 represents a substituted or unsubstituted alkoxy group having from 2 to 12 carbon atoms.

8. An indolylazaphthalide compound as claimed in any preceding claim, wherein X and Y each represents a hydrogen atom, an alkyl group having from 1 to 12 carbon atoms, an alkoxy group having from 1 to 12 carbon atoms, a chlorine atom, a bromine atom, a nitro group, a mono- or dialkylamino group having from 1 to 12 carbon atoms or a monoacylamino group having from 1 to 12 carbon atoms.

9. Any of the indolylazaphthalide compounds defined in Examples 1 to 14 hereinbefore.

10. A pressure-sensitive recording material comprising an indolylazaphthalide compound as claimed in any of Claims 1 to 9.

11. A heat-sensitive recording material comprising an indolylazaphthalide compound as claimed in any of Claims 1 to 9.

12. A recording material substantially as hereinbefore described in Example. 15 or 16.