GB2220671A

GB2220671A - New carbazolyl methane compounds for use as colour-formers

Info

Publication number: GB2220671A
Application number: GB8915963A
Authority: GB
Inventors: Mutuo Shiraishi; Manabu Yamada; Kozo Mizuno; Katsuhiko Tsunemitsu
Original assignee: Yamada Chemical Co Ltd
Current assignee: Yamada Chemical Co Ltd
Priority date: 1988-07-16
Filing date: 1989-07-12
Publication date: 1990-01-17
Anticipated expiration: 2009-07-12
Also published as: GB8915963D0; JPH0226782A; GB2220671B

Abstract

New carbazolyl methane compounds are of formula (I). <IMAGE> wherein R<1> and R<2> are each H or C1-5alkyl; R<3> is H or Me; R<4> is H, Me or OMe; and R<5> is H, C1-3alkyl or C1-3alkoxy. The carbazolyl methane (I) are white or slightly light yellow in color, are highly soluble in organic solvents, do not practically develop a color by themselves, and on close contact with an electron receiving substance, slowly form a blue or bluish purple color and the developed color image is excellent in light-resistance. They may be used in heat- or pressure-sensitive paper.

Description

Improvements in or Relating to Colour Developing Recording Materials The present invention relates to a color-developing recording material, containing, as a color-developing substance, a carbazolyl methane compound represented by the formula (I):

[wherein R1 and R2 independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R3 represent a hydrogen atom or a methyl group, R4 represents a hydrogen atom, a methyl group or a methoxy group and R5 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms], the color-developing substance being an electron donating compound which by itself is white or slightly light yellow in color and which, on contact with an electron accepting substance, develops a dark blue color.The concrete uses found for this color-developing recording material include a pressure-sensitive recording paper and a thermosensitive recording paper, for example.

As color-developing colorless substances capable of developing color in blue or bluish purple, leuco dyes such as phthalide compound represented by crystal violet lactone, spiropyran compounds, phenothiazinc compounds, and triphennl methane compounds have been heretofore reduced to actual use. Since these leuco dyes, have their own self-coloring property, and after their color are developed, have their own color hue, color density, color-developing speed, lightresistance and so on, the practice of combining several color-developing dyes and enhancing the color effect so as to suit the purpose of the use has been in vogue.

For example, the crystal violet lactone (hereinafter referred to as "CVL") which is renowned as a leuco dye capable of coloring in blue is quick in color-developing but is deficient in light-resistance. More often than not, therefore, it is used as combined with a blue-coloring leuco dye which is excellent in light-resistance but is slow in color-developing. Only a couple of leuco dyes of this kind, such as benzoyl leuco methylene blue and 3- [4,4'-bis(N-methylanili no)--b enzhydrvll-9-n- butylcarbazole, have been actually used and the situation hardly deserves to be satisfactory.

The present inventors, urged to overcome these problems, have continued a diligent and earnest study to develop a color-developing substance which can develop blue or bluish purple color in high density without coloring by itself. As the result, they have found that the novel carbazolyl methane compounds synthesized by the inventors solve the above problems and the present invention has been attained.

An object of the present invention is to provide a novel carbazolyl methane compound represented by the formula (I):

[wherein R1 and R2 independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R3 represents a hydrogen atom or a methyl group, R4 represents a hydrogen atom, a methyl group or a methoxy group and R5 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having l to 3 carbon atoms).

A further object of the present invention is to provide a recording material which contains, as a color-developing substance, a carbazolyl methane compound represented by the formula (I) described above.

The novel carbazolyl methane compound of the present invention represented by the formula (I) is white or slightly light yellow in color, is highly soluble in organic solvents such as, diaryl ethancs, alkyl naphthalenes, hydrogenated terphenyls and alkyl biphenyl, does not practically develop a color by itself and, on close contact with an electron accepting substance such as, an organic acid, an acid clay, a phenol formalin resin, a metal salt of an aromatic carboxylic acid or bis-phenol A, slowly develops a blue or bluish purple color::

[wherein R1 and R2 independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, R3 represents a hydrogen atom or a methyl group, R4 represents a hydrogen atom, a methyl group or a methoxy group and R5 represents a hydrogen atom, an alkyl group having I to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms].

The carbazolyl methane compounds of the present invention can be used either singly or in the fonn of a mixture of two or more. They can also be used as a mixture with other known color-developing substance such as, 3,3-bis(4 dimethylaminophenyl)-6-dimethylamino phthalide (hereinafter referred to as "CYL"), di-substituted fluorane compounds described in British Patent 1,282,743 and Belgian Patents 815,291 and 815,294, and bis-indolyl phthalides described in German Patent 2,259,711 for a recording material.

The novel carbazolyl methane compound of the present invention represented by the formula (I) is synthesized by subjecting a Sbenzyloxydiphenyl amine derivative represented by the formula (2) to a condensation reaction with a 3-formylcarbazole derivative represented by the formula (3) in an organic solvent, for instance, an alcohol such as methyl alcohol, ethyl alcohol or isopropyl alcohol, a halogenated hydrocarbon such as, ethylene chloride or tetrachloroethylene or diethylene glycol monomethyl ether, in the presence of p-toluene sulfonic acid, phosphoryl chloride or sulfuric acid.

The 4-benzyloxydiphenyl amine derivative of the formula (2) used in this synthesis is easily obtained by having a 4-hydroxydiphenyl amine derivative represented by the formula (4) to react with a benzyl halide in an organic solvent such as, alcohols, diethylene glycol monomethyl ether, N,N-dimethyl formamide or dimethyl sulfoxide in the presence of an alkali such as, sodium hydroxide, potassium hydroxide, sodium carbonate, sodium hydrogen carbonate or potassium carbonate.

As a color-developing substance for a recording material, particularly for a pressure-sensitive recording paper and a thermosensitive recording paper, the novel carbazolyl methane compounds according to the present invention have excellent qualities never found in the conventional phthalide compounds.

These excellent qualities will be demonstrated hereinafter by comparing the novel compounds of the present invention, that are, 3-[4,4'-bis(N-methyl-4 benzyloxyanilino)b enzhydyl]-9-n-butylcarbazole (hereinafter referred to as "A"); 3-[4,4'-bis(N-n-butyl-4-benzyloxyanilino)benzhydryl]-9-methylcarbazole (hereinafter referred to as "B"); 3-[4,4'-bis(N-methyl-4-benzyloxyanilino)-benzhydryl]-9- ethylcarbazole (hereinafter referred to as "C"); and 3-[4,4'-bis(N-methyl-4 benzyloxyanilino)benzhydryl]-9-methylcarbazole (hereinafter referred to as with CVL as one of known phthalide compounds; 4,4',4"-tris(Nmethylanilino)triphenyl methane (hereinafter referred to as "E") as one of triphenyl methane compounds described in Japanese Patent Publication No. 5652,758 (1981); and 3-[4,4'-bis(N-methylanilino)benzhydryl]-9-n-butylcarbazole (hereinafter referred to as "F") as one of carbazolyl methane compounds described in Japanese Patent Publication No. 56-12,515(1981).

The structural formulae of the compounds (A) to (F) and CvL are shown below.

(1) Comparison in light-resistance: Each 7 g of compound (A) and CVL were separately dissolved in 93 ml of KMC-113 (alkyl naphthalene, manufactured by Kureha Kagaku Kogyo K.K.).

The resultant each solution was microcapsulated by a conventional method and the capsules obtained were coated on a paper to prepare an upper-sheet of recording paper, respectively. Each of the upper sheet was closely attached to a sheet of paper coated with acid clay as an acidic electron acceppting adsorbent and the laminated sheets of paper were exposed to writing pressure with a ballpoint pen or a typewriter to obtain corresponding image in blue color on the surface of paper coated with acid clay.

The maximum density of the colored image and residual density ratio of the image exposed to sunlight for 6 hours were measured with a reflection densitometer (manufactured by McBeth Corp. and marketed under the name of "McBeth RD-514") utilizing a Wratten filter No. 25. The results are shown in Table 1.

Table 1

Compound Maximum Density Residual Density Ratio (%) A 0.95 89 CVL 0.82 63 It can be seen from Table 1 that the carbazolyl methane compound (A) of the present invention exhibited an image which is extremely refractory to sunlight compared to CVL and, therefore, is an outstanding light-resistant leuco dye with slow color-developing speed.

(2) Comparison in self-coloring property.

Each 50 mg of compounds (A) and (E) was separately dissolved in a mixture of 1 ml of KMC-113 (alkyl naphthalene, manufactured by Kureha Kagaku Kogyo KK.) and 4 ml of lauryl benzene. With several drops of the respective resultant solutions, a sheet of neutral paper was coated and left at the temperature of 25 to 30 C for 8 days as it was. On the second and eighth days of leaving, color densities of each sheet were measured with a reflection densitometer (manufactured by McBeth Corp. and marketed under the name of "McBeth RD-514") utilizing a Wratten filter No.25. The results are shown in Table 2.

Table 2

Color Density Compound Second Day Eighth Day Second Day Eighth Day A 0.10 0.26 E 0.16 0.36 It can be seen from Table 2 that on a sheet of neutral paper, carbazolyl methane compound (A) of the present invention colored by itself to an extremely small extent as compared with triphenyl methane compound (E). This fact indicates that when compound (A) is used on a pressure-sensitive recording paper or a thermosensitive recording paper, the paper obtained is white in color and continues to be white even under exposure to light.

(3) Comparison in color-developing speed: Each 7 g of compounds (A), (B), (C), (D) and (F) were separately dissolved in 93 ml of KMC-113 (alkyl naphthalene, manufactured by Kureha Kagaku Kogyo K.K.). The resultant each solution was microcapsulated by a conventional method and the capsules obtained were coated on a paper to prepare an uppersheet of recording paper, respectively. Each of the upper sheet was closely attached to a sheet of paper coated with acid clay as an acidic electron accepting adsorbent and the laminated sheets of paper were exposed to writing pressure with a ball-point pen or a typewriter to obtain corresponding image in blue color on the surface of paper coated with acid clay.

The sheet of paper having the image was immediately put in a dark room and left for 24 hours as it was. The color density of each image after 24 hours leaving were measured with a reflection densitomOter (manufactured by RIcBeth Corp. and marketed under the name of "McBeth RD-514") utilizing a Wratten filter No. 25. The results are shown in Table 3.

Table3

Compound Color Density A 0.62 B 0.67 C - 0.63 D 0.54 F 0.36 It can be seen from Table 3 that the color-developing speeds of carbazolyl methane compounds (A), (B), (C) and (D) of the present invention are enhanced by the presence of a benzyloxy group and therefore very large compared with the speed of compound (F).

(4) Comparison in maximum density achieved: Each 7 g of compounds (A), (B), (C), (D) and (F) was separately dissolved in 93 ml of KMC-113 (alkyl naphthalene, manufactured by Kureha Kagaku Kogyo K.K.). The resultant each solution was microcapsulated by a conventional method and the capsules obtained were coated on a paper to prepare an uppersheet of recording paper, respectively. Each of the upper sheet was closely attached to a sheet of paper coated with a metal salt of an aromatic carboxylic acid as an acidic electron accepting adsorbent and the laminated sheets of paper were exposed to writing pressure with a ball-point pen or a typewriter to obtain corresponding image in blue color on the surface of paper coated with the metal salt.

The maximum density of each colored image achieved was measured with a reflection densitometer (manufactured by McBeth Corp. and marketed under the name of "McBeth RD-514") utilizing a Wratten filter No. 25. The results are shown in Table 4.

Table 4

Maximum Density Compound 4chieved Achieved A 0.51 B 0.45 C 0.53 D 0.47 F 0.33 As can be seen from Table 4, carbozolyl methane compounds (A), (B), (C) and (D) of the present invention can exhibit very dense images in blue or bluish purple color on a surface of the paper coated with a metal salt of an aromatic carboxylic acid as compared with compound (F).

Synthesis of the novel carbazolyl methane compounds of the present invention represented by the formula (I) will be described in the following Examples.

EXAMPLE 1 (Synthesis of Compound D):

In 5.8 g of N-methyl-4-benzyloxydiphenyl amine, 2.5 g of N-methyl-3formylcarbazole, 0.8 g of p-toluenesulfonic acid (monohydrate) and 30 ml of ethyl alcohol were added and reacted at 70"C for 27 hours. The reaction mixture obtained was poured into 100 ml of iced water, neutralized with caustic soda and extracted with 50 ml of toluene under vigorous agitation. The toluene layer was separated and toluene was distilled off. The residue was dissolved in 10 ml of N,N-dimethylformamide and the solution was added to 200 ml of methyl alcohol dropwise. The deposited light yellow product was filtered and 7.1 g of 3-04,4'- bis(N-methyl-4-benzyloxyanilino)benzhydryl]-9-methylcarbazole was obtained.

This methylcarbazole develops blue color having Amax at 625 nm on acid clay and the color image obtained possesses a good light-resistance.

EXAMPLE 2 (Synthesis of Compound A):

In 5.8 g of N-methyl-4-benzyloxydiphenyl amine, 3.0 g of N-n-butyl-3 formylcarbazole, 0.8 g of p-toluenesulfonic acid and 30 ml of ethyl alcohol were added and reacted at 70"C for 24 hours. The reaction mixture obtained was poured into 100 ml of iced water, neutralized with caustic soda and extracted with 50 ml of tetrachloroethylene under vigorous agitation. The tetrachloroethylene layer was separated and 30 ml of tetrachloroethylene was distilled off. The residue was cooled from outside with ice and the deposits was filtered. 6.9 g of 3 [4,4'-bis(N-methyl-4-benzyloxyanilino)benzhydryl]-9-n-butylcarbazole, white in color, was obtained.This butylcarbazole develops blue color having Amax at 625 nm on acid clay and the color image obtained possesses a good light-resistance.

The melting point of compound A is 97 to 103"C.

EXAMPLE 3 (Synthesis of Compound C):

18.2 g of N-methyl-4-benzyloxydiphenyl amine, 6.7 g of N-ethyl-3formylcarbazole, 2.9 g of p-toluenesulfonic acid and 90 ml of diethylene glycol monomethyl ether were treated in the same manner as in Example 1 and obtained 20.7 g of 3-E4,4'-bis(N-methyl-4-benzyloxyanilino)benzhydryl]-9ethylcarbazole. This ethylcarbazole developed blue color having Amax at 625 nm on acid clay and the color image obtained possesses a good light-resistance.

EXAMPLE 4:

20 g of N-ethyl-4-benzyloxydiphenyl amine, 7.5 g of N-n-butyl-3 formylcarbazole, 2.9 g of p-toluenesulfonic acid and 90 ml of diethylene glycol monomethyl ether were treated in the same manner as in Example 1 and obtained 22.4 g of 3-[4,4'-bis(N-ethyl-4-benzyloxyanilino)benzhydryl]-9-nbutylcarbazole. This butylcarbazole developed blue color having Amax at 618 nm on acid clay and the color image obtained possesses a good light-resistance.

EXAMPLE 5 (Synthesis of Compound B):

6.6 g of N-n-butyl-4-benzyloxydiphenyl amine, 4.2 g of N-methyl-3- formylcarbazole, 0.8 g of p-toluenesulfonic acid and 30 ml of diethylene glycol monomethyl ether were treated in the same manner as in Example 1 and obtained 11 g of 3-[4,4'-bis(N-n-butyl-4-benzyloxyanilino)benzhydryl]-9- methylcarbazole. This methylcarbazole developed blue color having Amax at 625 nm on acid clay and the color image obtained possesses a good light-resistance. EXAMPLE 6 (Color Developing): Carbazorylmethane compounds represented by the formula (I) having other substituent than hydrogen atom for any of R3, R4 and R5 were synthesized in the same manner as in Examples 1 to 5.By contacting with acid clay, the carbazorylmethane compounds synthesized developed blue or bluish purple color.

The results are shown in Table 5.

Table 5

No. R1 R2 R3 R4 R5 Color Tone 6 C5H11 C2115 H H H Blue 7 CH3 C2H5 H 2-CH3 H Bluish purple 8 CH3 C4119 H 2-CH3 3-CH3 Blue 9 CH3 C4H9 4-CH3 2-CH3 2-CH3 Blue 10 CH3 C9 H 2-OCH3 H Bluish purple 11 CH3 C4H9 H 2-OCH3 2-C3H7 Bluish purple 12 CH3 C4H9 H 2-OCH3 2-OCH3 Bluish purple

Claims

Claims: 1. A carbazorylmethane compound ofthe formula (I):

wherein R1 and R2 independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; R3 represents a hydrogen atom or a methyl group; R4 represents a hydrogen atom, a methyl group or a methoxy group; and R5 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbonatoms.
2. 3-[4,4'-bis(N-methyl-4-benzyloxyanilino)benzhydryl]-9-n-butylcarbazole.
3. 3-[4,4'-bis(N-n-butyl-4-benzyloxyanilino)benzhydryl]-9-methylcarbazole.
4. 3-[4,4'-bis(N-methyl-4-benzyloxyanilino)benzhydryl]-9-ethylcarbazole.
5. 3-[4,4'-bis(N-methyl-4-benzyloxyanilino)benzhydryl]-9-methylcarbazole.
6. 3-[4,4'-bis(N-ethyl-4-benzyloxyanilino)benzhydryl]-9-n-butylcarbazole.
7. 3-[4,4'-bis(N-pentyl-4-benzyloxyanilino)benzhydryl]-9-ethylcarbazole.
8. 3-[4,4'-bis(N-methyl-4-benzyloxy-2-methylaIlilino)benzhydryl]-9- ethylcarbazol
9. 3-[4,4'-bis(N-methyl-4benzyloxy-2-methylanilino)-3 .3 '-dim ethyl- benzhydryl]-9-n-butylcarbazole .
10. 3-[4,4'-bis(N-methyl-4-(4-methylb enzyloxy)-2-me thylani lino}- 3, 3 '- dimethylbenzhydryl]-9-n-butylcarbazole .
11. 3-[4,4'-bis(N-methyl-4-benzyloxy-2-methoxyanilino)benzhydryl]-9-n- butylcarbazole.
12. 3-[4,4'-bis(N-methyi-4-b enzyloxy-2-methoxyanilino)-2,2'-di-n- propylbenzhydryl]-9-n-butylcarbazole .
13. 3-[4,4'-bis(N-methyl-4-benzyloxy-2-methoxyanilino)-2 ,2'-dimethoxy benzhydryl3-9-n-butyIcarbazoe .
14. A recording material which comprises a carbazorylmethane compound having the formula (I) as one of the colour developing substances.

wherein RI and R2 independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms; R3 represents a hydrogen atom or a methyl group; R4 represents a hydrogen atom, a methyl group or a methoxy group; and R5 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms or an alkoxy group having 1 to 3 carbon atoms.
15. The recording material according to claim 14, wherein said colordeveloping materials are a combination of said carbazorylmethane compound and a rapid color-developing leuco-dyestuff.
16. The recording material according to claim 15, wherein said rapid colordeveloping leuco-dyestuff is crystal violet lactone.
17. The recording material according to any one of claims 14 and 15, wherein said carb azorylmethane compound is 3-L4,4'-bis(N-methyl-4-benzyloKyanilino)- benzhydryl]-9-n-butylcarbazole
18. The recording material according to any one of claims 14 and 15, wherein said carbazorylmethane compound is 3-[4,4'-bis(N-n-butyl-4-benzyloxyanilino)benzhydryl]-9-methylcarbazole
19. The recording material according to any one of claims 14 and 15, wherein said carb azorylmethane compound is 3-[4,4'-bis(N-methyl-4-benzyloxyanilino) benzhydryl]-9-ethylcarbazole
20.The recording material according to any one of claims 14 and 15, wherein said carbazorylmethane compound is 3-[4,4'-bis(N-methyl-4-benzyloxyanilino) benzhydryl]-9-methylcarbazolc
21. The recording material according to any one of claims 14and 15, wherein said carbazorylmethane compound is 3-[4,4'-bis(N-ethyl-4-benzyloxyanilino) benzhydryl]-9-n-butylcarbazole .
22. The recording material according to any one of claims 14 and 15, wherein said carbazorylmethane compound is 3-[4,4'-bis(N-pentyl-4benzyloxyanilino) benzhydryl]-9-ethylcarbazole .
23. The recording material according to any one of claims 14 and 15, wherein said carbazorylmethane compound is 3-[4,4'-bis(N-methyl-4-benzyloxy-2-methyl anilino)benzhydryll-9-ethylcarbazole .
24. The recording material according to any one of claims 14 and 15, wherein said carbazorylmethane compound is 3-[4,4'-bis(N-methyl-4-benzyloxy-2-methylanilino)-3 ,3'-dimethylbenzhydryl]-9-n-butylcarbazole .
25. The recording material according to any one of claims 14 and 15, wherein said carbazorylmethane compound is 3-[4,4'-bis{N-methyl-4-(4-methylbenzyloxy)-2-methylanilino}-3 ,3'-dimethylb enzhydryl]-9 -n-butylcarb azole .
26. The recording material according to any one of claims 14 and 15, wherein said carbazorylmethane compound is 3-t4,4'-bis(N-methyl-4-benzyloxy-2- methoxy-anilino)benzhydryl]-9-n-butylcarbazole .
27. The recording material according to any one of claims 14 and 15, wherein said carbazorylmethane compound is 3-[4,4'-bis(N-methyl-4-benzyloxy-2- methoxy-anilino)-2,2'-di-n-propylbenzhydryl]-9-n-butylcarbazole .
28. The recording material according to any one of claims 14 and 15, wherein said carb azorylmethane compound is 3 -(4,4'-bis(N-methyl-4-benzyloxy- 2- methoxy-anilino)-2 ,2'-dimethoxybenzhydryl]-9-n-butylcarbazolt