US3736168A

US3736168A - Pressure-sensitive phthalide compound copying papers

Info

Publication number: US3736168A
Authority: US
Inventors: M Ozutsumi; Y Miyazawa; K Motohashi; S Ogawa; S Mishima
Original assignee: Hodogaya Chemical Co Ltd; Fuji Photo Film Co Ltd
Current assignee: Fujifilm Holdings Corp; Hodogaya Chemical Co Ltd
Priority date: 1970-05-15
Filing date: 1971-05-17
Publication date: 1973-05-29
Anticipated expiration: 1990-05-29
Also published as: FR2090067A1; DE2124084B2; DE2124084A1; IE35853L; IE35853B1; FR2090067B1; ES391549A1; GB1310322A; CA933356A

Abstract

A PRESSURE-SENSITIVE TRANSFERRING SHEET, ADAPTED FOR USE WITH ANOTHER SHEET HAVING AN ELECTRON ACCEPTING LAYER, COMPRISING A SUPPORT HAVING THEREON A PRESSURE-RUPTURABLE MICROCAPSULE LAYER, SAID MICROCAPSULE CONTAINING AN OIL HAVING DISSOLVED THEREIN AS A COLOR FORMER AT LEAST ONE PHTHALIDE COMPOUND REPRESENTED BY THE FOLLOWING GENERAL FORMULA

1-(4-(R1-N(-R2)-)PHENYL),1-(1-R3,2-R4-INDOL-3-YL),3-(O=),

4-X1,5-X2,6-X3,7-X4-PHTHALAN

WHEREIN X1, X2, X3, X4, R1, R2, R3 AND R4 ARE DESCRIBED HEREINAFTER, IS DISCLOSED.

Description

United States Patent US. Cl. 117-362 2 Claims ABSTRACT OF THE DISCLOSURE A pressure-sensitive transferring sheet, adapted for use with another sheet having an electron accepting layer, comprising a support having thereon a pressure-rupturable microcapsule layer, said microcapsule containing an oil having dissolved therein as a color former at least one phthalide compound represented by the following general formula wherein X X X X R R R and R are described hereinafter, is disclosed.

BACKGROUND OF THE INVENTION The present invention relates generally to a pressuresensitive copying paper and more particularly it relates to a pressure-sensitive copying paper having a microcapsule layer containing a phthalide compound as a color former.

DESCRIPTION OF THE PRIOR ART Pressure-sensitive copying papers are usually composed of a transferring sheet having thereon a layer of fine capsules containing therein a solution of an electron donating colorless organic compound (hereinafter the organic compound is called the color former) in an oil, and a receiving sheet, having thereon a layer of an electron-accepting solid and a suitable binder. When both sheets are put together such that the electron donating layer is brought into contact with the electron accepting layer, and the piled sheets are pressed locally by handwriting or typewriting, the capsules at the pressed areas are ruptured and the colorless color former contained in the capsules is adsorbed on the solid acid to form a color. There have also been employed pressure-sensitive copying paper systems consisting of the aforesaid transferring sheet (hereinafter, this sheet is called the upper sheet) and a receiving sheet (hereinafter this sheet is called the under sheet), and an intermediate sheet (hereinafter this sheet is called the middle sheet) having coated on the opposite sunfaces a layer of microcapsules containing the color former solution and a layer of the solid acid and a binder.

As the electron accepting solid acid, there are known acid clay, attapulgite, zeolite, bentonite, kaolin, and the like. As an organic solvent for dissolving the color former, there are illustrated ethylene glycol, chlorobenzene, and chlorodiphenyl.

In general, Crystal Violet Lactone has widely been used as a purple-color former. However, although Crystal Violet Lactone is immediately colored purple-blue when it is brought into contact with an electron-accepting solid acid, there are such disadvantages that the color is weak in light fastness and also the purple-blue vanishes by the action of water.

Benzoyl Leuco Methylene Blue has been used as a blue-color former. When the color former is brought into contact with an electron accepting solid acid, a blue color having good light fastness is formed but the color former has such a disadvantage that it takes a long period of time until it colors.

Therefore, it has widely been practiced to use the mixture of Crystal Violet Lactone and Benzoyl Leuco Methylene Blue but for the reasons mentioned above, the color formed on the pressure-sensitive copying papers using the mixture of these color formers changes gradually from purple-blue to blue and to dark blue with the passage of time.

Recently, pressure-sensitive copying sheets in which a carbazole-substituted phthalide compound is used as the color former were disclosed by Chao-Han Lin and Dayton in US. Pat. No. 3,540,910. However, the compound described in the specification of the patent has such disadvantages that the color obtained by the contact thereof with an electron-accepting solid acid changes from purple to green-blue with the passage of time and also the color is weak in water resistance.

An object of the present invention, is therefore, to provide pressure-sensitive copying papers containing as a color former the phthalide compound represented by the aforesaid general formula which is immediately colored when it is brought into contact with a solid acid to pro vide a stable purple or blue color having excellent light fastness and water resistance.

Another object of this invention is to provide pressuresensitive copying papers which can be colored black by using the phthalide compound represented by the aforesaid general formula together with other known color formers.

SUMMARY OF THE INVENTION According to the present invention, there is provided a pressure-sensitive copying paper containing as a color former the phthalide compound represented by the general formula 0--o=0 X R1\ i R2 x x 4 8 O-Rl \N h wherein when X X X and X each represents a hydrogen atom,

R and R each represents a hydrogen atom, a methyl group, or an ethyl group, R represents a phenyl group, with the possibility that said phenyl group may have a methyl group as a substituent, and R represents a methyl group or an ethyl group;

when X, and X each represents a hydrogen atom and one of X and X represents a hydrogen atom while the other of X and X, represents a dimethylamino group or a diethylamino group, R and R each represents a hydrogen atom, a methyl group or an ethyl group, R represents a phenyl group, with the possibility that said phenyl group may have a methyl group or an ethoxy group as a substituent, and R represents a methyl group, an ethyl group or a phenyl group; and when X X X and X each represents a chlorine atom, R and R each represents a hydrogen atom, a methyl group or an ethyl group, R represents a methyl group, an ethyl group, or a phenyl group, with the possibility that said phenyl group may have a methyl group or an ethoxy group as a substituent, and R represents a methyl group, an ethyl group, or a phenyl group.

DETAILED DESCRIPTION OF THE INVENTION The phthalide compound used in this invention represented by the general formula described above may be prepared by reacting the corresponding benzophenonecarboxylic acid and indole or the corresponding benzoyl indole and an aromatic amine for 10-120 minutes at a reaction temperature of 50-140 C., in the presence of a condensing agent such as acetic anhydride or phosphorus oxychloride using, if necessary, a volatile organic inert solvent such as chloroform, benzene, or chlorobenzene, pouring the reaction product in ice-cooled water to hydrolyze the condensing agent, adding the volatile organic inert solvent described above, alkalizing the reaction prod-- uct with an aqueous solution of sodium hydroxide, recovering the solvent layer, and distilling away the solvent therefrom under a reduced pressure.

Examples of producing such phthalide compounds used in this invention will be explained below in detail.

PRODUCTION EXAMPLE 1 A mixture of 5.0 g. of 4'-(N-methyl-N-pethoxyphenylamino)-5(or 4) dimethylamino-benzophenone-Z-carboxylic acid, 2.0 g. of 1,2-dimethyl indole, and 25 g. of acetic anhydride was heated to 9095 C. for 60 minutes with stirring to cause the reaction. The reaction product thus produced was poured in 750 g. of ice-water to hydrolize the acetic anhydride, and after adding thereto 200 g. of benzene, thepH of the mixture was adjusted to 12 by adding an aqueous solution of sodium hydroxide. The benzene layer formed was recovered by decantation and after treating the benzene layer with activated carbon, benzene was distilled away under a reduced pressure. Then, by recrystallizing the residue from an alcohol, 5.0 g. of 3-(4-N-methyl-N-p-ethoxyphenylaminophenyl)-3-( 1, 2-dimethylindole-3-il)-5 (or 6) dimethylaminophthalide represented by the following formula Ha CH3 N AH.

was obtained as a light-yellow color former having a melting point of 145-150 C. When a benzene solution of the color former thus prepared was brought into contact with an acid clay layer coated on a paper, the color former was immediately colored purple.

PRODUCTION EXAMPLE 2 5 (or 6)-dimethylaminophthalide represented by the 01 lowing formula (EH: i

as a light-orange color former having a melting point of 124--128 C. When a benzene solution of the color former was brought into contact with acid clay, the color former was immediately colored blue.

PRODUCTION EXAMPLE 3 A mixture of 3.0 g. of 4'-(N-methyl-N-p-ethoxypheny1- amino)-5 (or 4) dimethylamino-benzophenone-2-carboxylic acid, 1.8 g. of l-ethyl-Z-phenylindole, and 15 g. of acetic anhydride was heated to 95 C. for 60 minutes with stirring. Then, the reaction product thus obtained was treated as in Production Example 1 to provide 2.7 g. of 3-(4 N-methyl-N-p-ethoxyphenylamino-phenyl) 3 (lethyl-2-phenylindole-3-il)-5 (or 6) dimethylaminophthalide as a light-orange color former having a melting point of -l16 C.-When a benzene solution of the color former was brought into contact with an acid clay layer coated on a paper, the color former was immediately colored blue.

PRODUCTION EXAMPLE 4 To 30 g. of monochlorobenzene were added 3.8 g. of 1- methyl-2phenyl-3- [2-carboxy 5(or 4) dimethylaminobenzoyl]-indole and 1.9 g. of p-methyldiphenylamine and thereafter, 3.1 g. of phosphorus oxychloride was added to the mixture. The resultant mixture was heated to 85-90 C. for minutes with stirring to cause the reaction and the reaction product thus obtained was treated as in Production Example 1 to provide 3-(4-N-p-methylphenylamino-phenyl)3-(1 methyl-Z-phenylindole 3 il)-5 (or 6)-dimethylaminophthalide represented by the following formula as a light-brown color former having a melting point of l56161 C. When a toluene solution of the color former was brought into contact with an acid clay layer formed $1 a paper, the color former was immediately colored PRODUCTION EXAMPLE 5 A mixture of 3.9 g. of l-methyl-Z-phenyl-S-[2-carboxy- 5 (or 4)-dietl1ylaminobenzoyl]-indole, 1.9 g. of N-methyldiphenylamine, and 10 g. of acetic anhydride was heated to -140" C. for 30 minutes with stirring to cause the reaction. The reaction product thus obtained was treated as in Production Example 1 to provide 3-(4-N-methyl-N- phenylammophenyl)-3-(l-methyl 2 phenyl-indole-3-il)- 5 (or 6)-diethylaminophthalide having the following formula N- C 2H5 as a light-brown color former having a melting point of 105-111 C. When a benzene solution of the color former was brought into contact with an acid clay layer on a paper, the color former was immediately colored blue.

PRODUCTION EXAMPLE 6 To 30 g. of monochlorobenzene were added 3.3 g. of 4-(o-toluidino)-benzophenone-Z-carboxylic acid and 1.5 g. of 1,2-dimethylindole and then 3.1 g. of phosphorus oxychloride was further added to the mixture. The resultant mixture was heated to 75-80 C. for 120 minutes with stirring and the reaction product was treated as in Production Example 1 to provide 3.4 g. of 3-(4-N-o-methylphenylamino-phenyl) 3( 1,2 dimethylindole 3 i1)- phthalide represented by the following formula Q- -Q-i-Q as a light-brown color former having a melting point of 151157 C. When a toluene solution of the color former was brought into contact with an acid clay layer formed on a paper, the color former was immediately colored purple.

PRODUCTION EXAMPLE 7 M mi-(a as a light-brown color former having a melting point of 103-109 C. When a toluene solution of the color former was brought into contact with an acid clay layer formed on a paper, the color former was immediately colored purple.

PRODUCTION EXAMPLE 8 A mixture of 2.9 g. of 2-ethyl-3-(2-carboxybenzoyl)- indole, 2.1 g. of N-ethyldiphenylamine, and 2.9 g. of zinc chloride was heated to 120-130 C. for 180 minutes with stirring to cause the reaction. The reaction product was 6 treated as in Production Example 1 to provide 3.1 g. of 3 (4 N ethyl-N-phenyl-amino-phenyl)-3-(2-ethylindole-3-il)-phthalide represented by the following formula Q- -Q-l-Q as a light-brown color former having a melting point of 97 C. When a toluene solution of the color former thus obtained was brought into contact with an acid clay layer formed on a paper, the color former was immediately colored purple.

PRODUCTION EXAMPLE 9 A mixture of 2.8 g. of 4'-dimethylamino-3,4,5,6-tetrachlorobenzophenone-Z-carboxylic acid, 1.0 g. of 1,2-dimethylindole, and 15 g. of acetic anhydride was heated to 90-98 C. for minutes with stirring to cause the reaction. The reaction product thus obtained was treated as in Production Example 1 to provide 3.0 g. of 3-(4-dimethylaminophenyl) 3-(1,2-dimethylindole-3-il)-4,5,6,7- tetrachlorophthalide represented by the following formula as a light-yellow-white color former having a melting point of 223226 C. When a benzene solution of the color former thus obtained was brought into contact with an acid clay layer formed on a paper, the color former was immediately colored blue.

PRODUCTION EXAMPLE 10 A mixture of 2.8 g. of 4-dimethylamino-3,4,5,6-tetrachlorobenzophenone-Z-carboxylic acid, 1.6g. of 1-methyl- Z-phenylindole, and 15 g. of acetic anhydride was heated to l35l36 C. for 30 minutes with stirring to cause the reaction. Then the reaction product was treated as in Production Example 1 to provide 2.8 g. of 3-(4-dimethylaminophenyl) 3-(1-methyl-2-phenylindole-3-il)-4,5,6,7- tetrachlorophthalide represented by the. following formula CHa as a light-yellow color former having a melting point of 239243 C. When a benzene solution of the color former thus obtained was brought into contact with an acid clay layer formed on a paper, the color former was immediately color green-blue.

PRODUCTION EXAMPLE 11 A mixture of 2.5 g. of l-ethyl-2-phenyl-3-(2-carboxy- 3,4,5,6tetrachlorobenzoyl)-indole, 0.6 g. of dimethylaniline, and g. of acetic anhydride was heated with stirring to 135-136 C. for 30 minutes to cause the reaction. Then the reaction product obtained was treated as in Production Example 1 to provide 2.1 g. of 3-(4-dimethylaminophenyl)-3-(1 ethyl 2 phenylindole-B-il)-4,5,6,7,-tetrachlorophthalide represented by the following formula CzHs as a light-yellow color former having a melting point of 195-201 C. When a benzene solution of the color former thus obtained was brought into contact with an acid clay layer formed on a paper, the color former was immediately colored green-blue.

PRODUCTION EXAMPLE 12 C-CHa i CH3 as a light-yellow color former having a melting point of 162-168 C. When a toluene solution of the color former produced was brought into contact with an acid clay layer formed on a paper, the color former was immediately colored blue.

PRODUCTION EXAMPLE 13 A mixture of 1.0 g. of 4'-(N-methyLN-p-ethoxyphenylamino)-3,4,5,6 tetrachlorobenzophenone 2 carboxylic acid, 0.3 g. of 1,2-dimethylindole, and 5.0 g. of acetic anhydride was heated with stirring to 135-136" C. for 30 minutes to cause the reaction and the reaction product obtained was treated as in Production Example 1 to provide 1.0 g. of 3-(4 N methyl-N-p-ethoxyphenylaminophenyl) 3 (1,2-dimethylindole-3-il)-4,5,6,7-tetrachlorophthalide having the following formula C-CHa as a light-yellow color former having a melting point of 144-150 C. When a benzene solution of the color former thus obtained was brought into contact with an acid clay layer formed on a paper, the color former was immediately colored blue.

8 PRODUCTION EXAMPLE 1.4

To 30 g. of monochlorobenzene were added 2.9 g. of 4-diethylamino-3,4,5,6-tetrachlorobenzophenone 2 -carboxylic acid and 1.0 g. of 2-ethylindole and then 2.8 g. of phosphorus oxychloride was further added thereto. The resultant mixture was heated with stirring to 7580 C. for minutes to cause the reaction and the reaction product was treated as in Production Example 1 to provide 2.5 g. of 3-(4-diethylaminophenyl)-3-(2-ethylindole- 3-il)-4,5,6,7-tetrachlorophthalide represented by the following formula Oils I NQC c1 (Dz Ha 1 CI CCzH as a light-yellow color former having a melting point of 198-205 C. When a toluene solution of the color former wasbrought into contact with an acid clay layer formed on a paper, the color former was immediately colored blue.

For producing the pressure-sensitive copying papers using as color formers the phthalide compounds represented by the general formula described above, the process described in the specifications of US. Pats. 2,548,366, 2,800,457, or 2,800,458, that is, the process of producing microcapsules by utilizing the phenomenon of forming composite coacervations may be employed. The amount of the color former to be used is generally 0.55.0% by weight based on the weight of the organic solvent described above, such as ethylene glycol, chlorobenzene, and chlorodiphenyl. I

The pressure-sensitive copying paper of this invention in which the phthalide compound represented by the afore- Said general formula is used as a color former is colorless or has a very faint yellow character before use, but when the pressure-sensitive copying paper is pressed locally by handwriting or typewriting, purple or blue coloring occurs instantly. Moreover, the color density of the color thus formed is high and the light and water resistance thereof are excellent.

Furthermore, by using the aforesaid color former together with known yellow-color formers, purple-color formers, blue-color formers, green-color formers, and the like, a pressure-sensitive copying paper capable of providing deep-black copying can be obtained unaccompanied with any adverse influences, such as, desensitization.

Now the present invention will further be explained in greater detail by the following examples.

EXAMPLE 1 In 100 g. of trichlorodiphenyl was dissolved 1.5 g. of 3-(4-N-methyl-N-p-ethoxyphenylamino-phenyl)-3 (1,2- dimethylindole-3-il)-5 (or 6)-dirnethylaminophthalide and then 20 g. of gum arabic and g. of water were added to the solution at 50 C. followed by emulsification. To the emulsion were added 20 g. of acid-treated gelatin and 160 g. of water and thereafter the pH of the emulsion was adjusted to 5 by adding acetic acid with stirring. Then, 500 g. of water was added to the system to cause the coacervation and to form the dense liquid films of gelatin-gum arabic around the oil drops of trichlorodiphenyl. Then, after adjusting the pH of the system to 4.4, 3.8 g. of aqueous 37% Formalin solution was added thereto to harden the aforesaid liquid films, the system was, then, cooled to 10 C., the pH thereof was adjusted to 9 by adding an aqueous sodium hydroxide solution, and the system was allowed to stand for 5-6 hours, whereby the encapsulation was finished completely. The microcapsule-containing liquid was applied to a paper by means of roll coating or air-knife coating and dried to give a colorless coated sheet. When the coated paper (upper sheet) was placed on a sheet (under sheet) having coated thereon a layer of an acid electron acceptive adsorbent so that the microcapsule layer was closely brought into contact with the adsorbent layer and a pressure was applied locally to them by hand-Writing or typewriting, the pressed areas of the under sheet were immediately colored purple.

When the color former thus colored purple was placed for a long period of time in a chamber free from the direct rays of the sun, no discoloring was observed and also when it is exposed to the direct rays of the sun for a long period of time, fading was scarcely observed. The color former thus colored also was excellent in Water resistance.

On the other hand, when the same procedure as above Was followed by using the known color formers, 3-(4-dimethylaminophenyl) 3 (1,2-dimethylindole-3-i1)-5-dimethylaminophthalide and 3-(4-dimethylaminophenyl)-3- (1,2-dimethylindol-3-il) 6 dimethylaminophthalide dis closed in the specification of U.S. Pat. No. 3,540,912, each of the color formers was colored immediately in purple on the under sheet but when the color formers thus colored purple were placed for a short period of time in a chamber free from the direct rays of the sun, they were discolored to dark purple and when they were further allowed to stand, they were discolored to greenish blue. These color formers thus colored had poor water resistance.

EXAMPLE 2 An upper sheet was prepared by following the same procedure as in Example 1 except that 1.5 g. of 3-(4-N- methyl-N-p-ethoxyphenylaminophenyl)-3-(1 methyl 2- phenylindole--il)-5(or 6)-dimethylaminophthalide was used as the color former and when the upper sheet was placed on the under sheet so that the microcapsule layer was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored blue. By testing the color former thus colored blue with respect to light fastness, it was confirmed that the color former thus colored had sufiicient stability for practical use. The colored color formed also was excellent in water resistance.

EXAMPLE 3 A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 1.5 g. of 3-(4- N methyl-N-p-ethoxyphen'ylamino-phenyl)-3-( 1-ethyl-2- phenylindole-3-il)-5 (or 6 dimethylaminophthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored blue. By testing the color former thus colored blue with respect to light fastness, it was confirmed that the color former thus colored had sufiicient stability for practical use. The color former colored also has excellent water resistance.

EXAMiPLE 4 A colorless upper sheet was prepared by follovn'ng the same procedure as in Example 1 except that 1.5 g. of 3- (4-N-p-methylphenylaminophenyl)-3 (1 methyl 2- phenylindole-3-il)-5(or 6)-dimethylaminophthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer of the upper sheet was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored blue. -By testing the color former thus colored blue, it was confirmed that the color former thus colored had sufiicient stability for practical use. The colored color former also was excellent in water resistance.

10 EXAMPLE 5 A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 1.5 g. of 3-(4- N-methyl-N-phenylarninophenyl)-3-(l-methyl-Z phenylindole-3-il)-5(or 6)-diethylaminophthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer of the upper sheet was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored blue. By testing the color former thus colored in blue with respect to light fastness, it was confirmed that the colored color former had sufficient stability for practical use. The colored color former also was excellent in water resistance.

EXAMPLE 6 A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 1.5 g. 3-(4'N- o methylphenylaminoph'enyl) 3-(1,2-dimethylindole-3-il) phthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer of the upper sheet was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored purple. By testing the color former thus colored purple with respect to light fastness, it was con firmed that the colored color former had sufficient stability for practical use. The colored color former also was excellent in water resistance.

EXAMPLE 7 A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 1.5 g. of 3 (4-N-methyl-N-phenylaminophenyl)-3-(2-ethylind0le- 3-il)-5 (or 6)-diethylaminophthalide was used on the under sheet so that the capsule layer of the upper sheet was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored purple. -By testing the color former thus colored purple with respect to light fastness, it was confirmed that the color former thus colored purple had sufficient stability for practical use. The colored color former also was excellent in water resistance.

EXAMPLE 8 A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 2.0 g. of 3- (4 N ethyl-N-phenylaminophenyl)-3-(2-ethylindole-3- il)-phthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer of the upper sheet was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored purple. By testing the color former thus colored purple with respect to light fastness, it was confirmed that the color former thus colored purple had suflicient stability for practical use. The colored color former also was excellent in water resistance.

EXAMPLE 9 A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 1.5 g. of 3 (4-dimethyla'minophenyl)-3-(1,2-dimethylindole-3-il)- 4,5,6,7-tetrachlorophthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer of the upper sheet was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored blue. When the color former thus colored blue was placed in a chamber free from the direct rays of the sun for a long period of time, no discoloring was observed and also when the colored color former was exposed to the direct rays of the sun for a long period of time, fading was scarcely observed. The colored color former also was excellent in water resistance.

On the other hand, when the same procedure as above was followed by using as the color former a known compound, 3-(4-dimethylaminophenyl)-3-(1,2-dirnethylindole- 3-il)-phthalide disclosed in the specification of US. Pat. No. 3,540,911, a bluish purple color was immediately obtained on the under sheet but when the color former thus colored bluish purple was placed in a chamber free from the direct rays of the sun for a short period of time, the colored color former was discolored to purple-blue and when the colored color former was further allowed to stand, it was discolored to greenish blue. The colored color former also had poor water resistance.

EXAMPLE A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 1.5 g. of 3- (4 dimethylaminophenyl) -3- 1-methyl-2-phenylindole-3- il) 4,5,6,7-tetrachlorophthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer of the upper sheet was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored green-blue. By testing the color former thus colored green-blue with respect to light fastness, it was confirmed that the colored color former had suflicient stability for practical use. The colored color former was also excellent in water resistance.

EXAMPLE 11 A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 1.5 g. of 3- (4 dimethylaminophenyl) 3-(l-ethyl-2-phenylindole-3- il) 4,5,6,7 tetrachlorophthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer of the upper sheet was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied to them by handwriting, the areas of the acid clay layer thus pressed were immediately colored greenish blue. By testing the color former thus colored with respect to light fastness, it was confirmed that the colored color former had sufficient stability for practical use. The colored color former was also excellent in water resistance.

EXAMPLE 12 A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 2.0 g. of 3 (4 o toluidinophenyl)-3-( 1,2-dimethylindole-3-il)- 4,5,6,7-tetrachlorophthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored blue. By testing the color former thus colored blue with respect to light fastness, it was confirmed that the colored color former had sufiicient stability for practical use.

EXAMPLE 13 A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 2.0 g. of 3- (4 N-methyl-N-p-ethoxyphenylaminophenyl)-3-(1,2-dimethylindole 3-il)-4,5,6,7-tetrachlorophthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer was closely brought into contact with the acid clay layer of the under layer and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored blue. By testing the color former thus colored blue with respect to light fastness, it was confirmed that the colored color former had sufficient stability for practical use. The colored color former also was excellent in water resistance.

EXAMPLE 14 A colorless upper sheet was prepared by following the same procedure as in Example 1 except that 1.5 g. of 3- (4 diethylaminophenyl) 3-(Z-ethylindole-B-il)-4,5,6,7- tetrachlorophthalide was used as the color former and when the upper sheet was placed on the under sheet so that the capsule layer of the upper sheet was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored blue. By testing the color former thus colored blue with respect to light fastness, it was confirmed that the colored color former had sufficient stability for practical use.

EXAMPLE 15 An upper sheet was prepared by following the same procedure as in Example 1 except that 0.5 g. of 3-(4-N- methyl-N-p-ethoxyphenylaminophenyl) 3 (l-methyl-Z- phenylindole 3 il)-5 (or 6)-dimethylaminophthalide, 0.8 g. of o-hydroxybenzalacetophenone, 0.8 g. of Rhodamine Banilinolactam, 0.2 g. of Crystal Violet Lactone, and 0.2 g. of Malachite Green Lactone were used as the color formers. When the upper sheet was placed on the under sheet so that the capsule layer was closely brought into contact with the acid clay layer of the under sheet and a localized pressure was applied onto them by handwriting, the areas of the acid clay layer thus pressed were immediately colored black. The color thus formed was very stable and also excellent in light and water resistance.

EXAMPLE 16 An upper sheet was prepared by following the same procedure as in Example 1 except that 0.5 g. of 3-(4-dimethylaminophenyl)-3-(1,2-dimethylindole-3-il) 4,5,6,7- tetrachlorophthalide, 0.8 g. of o-hydroxybenzalacetophenone, 0.2 g. of Crystal Violet Lactone, 0.8 g. of Rhodamine Bam'linolactam, and 0.2 g. of Malachite Green Lactone were used as the color formers. When the upper sheet was placed on the under sheet and a localized pressure was applied onto them by handwriting the areas of the acid clay layer thus pressed were immediately colored black. The color thus formed black was very stable and also excellent in water resistance.

What is claimed is:

1. A pressure-sensitive transferring sheet, adapted for use with another sheet having an electron-accepting layer, comprising a support and, coated on said support, a layer containing pressure rupturable microcapsules, said microcapsules containing an oil and dissolved therein a color former comprising at least one phthalidc compound represented by the general formula phenyl group or a methyl substituted phenyl group, and R represents a methyl group or an ethyl group;

when X and X each represents a hydrogen atom and when one of X or X, represents a hydrogen atom while the other represents a dimethylamino group or a diethylamino group, R and R each represents a hydrogen atom, a methyl group or an ethyl group, R represents a phenyl group or a methyl-substituted or ethoxy-substituted phenyl group, and R represents a methyl group, an ethyl group or a phenyl group; and

when X X X and X each represents a chlorine atom, R and R each represents a hydrogen atom, 'a methyl group or an ethyl group, R represents a methyl group, an ethyl group, a phenyl group or a methyl-substituted or an ethoxy-substituted phenyl group, and R represents a methyl group, and ethyl group, or a phenyl group.

2. The pressure-sensitive transferring sheet as claimed in claim 1, wherein said phthalide compound is selected from the group consisting of 3-(4- N-methyl-N-p-ethoxyphenylamino-phenyl) 3 (1,2 dimethylindole-3-il)-5- (or 6)-dimethylaminophthalide,

3 (4-N-methyl-N-phenylamino-phenyl -3 1-methyl-2- phenylindole-3-il) -5 (or 6 -diethylaminophthalide,

3- (4-N-o-methylphenylamino-phenyl) -3-( 1,2-dimethylindole-3-il -phthalide,

3 4-N-methyl-N-phenylamino-phenyl -3 (2-ethylindole-3 -i1 -5 (or 6) -diethylaminophthalide,

3- (4-N-ethyl-N-phenylamino-phenyl) -3 (2-ethylindole- 3 -i1) -phthalide,

3-(4-dimethylaminophenyl)-3-(1,2-dimethylindo1e-3- il) -4,5,6,7-tetrachlorophthalide,

3- (4-dimethylaminophenyl) -3- l-methyl-Z-phenylindole-3 -il) -4, 5 ,6,7-tetrachl0r0phthalide,

3- (4-dlmethylaminophenyl) -3 1-ethyl-2-phenylindole- 3-il) -4,5,6,7-tetrachlorophthalide,

3 (4-N-o-methylphenylamino-phenyl) -3- 1,2-dimethylind01e-3 -il -4,5, 6,7-tetrachlorophthalide,

3- (4-N-methyl-N-p-ethoxyphenylamino-phenyl) -3 1,2-

dimethylindole-3 -il -4,5,6,7-tetrachlorophtha1ide, and

3, (4-diethylaminophenyl) -3- (2-ethylindole-3 -il) -4,5,

6,7-tetrachlor0phthalide.

References Cited UNITED STATES PATENTS 3,540,911 11/1970 Lim 1l736.8 3,540,912 11/1970 Lim 11736.8

MURRAY KATZ, Primary Examiner US. Cl. X.R.