US3345293A

US3345293A - Colored electrostatographic toners containing organic dye pigments

Info

Publication number: US3345293A
Application number: US306345A
Authority: US
Inventors: John S Bartoszewicz; Michael A Insalaco
Original assignee: Xerox Corp
Current assignee: Xerox Corp
Priority date: 1963-09-03
Filing date: 1963-09-03
Publication date: 1967-10-03
Anticipated expiration: 1984-10-03
Also published as: JPS4946951B1; JPS50777B1; JPS50776B1; GB1074147A; JPS4927228A

Description

United States Patent 3,345,293 COLORED ELECTROTATGGRAPHIC TONERS CONTAINING ORGANIC DYE PIGMENTS John S. Bartoszewicz, Rochester, and Michael A. Insalaco,

Webster, N.Y., assignors to Xerox Corporation, Rochester, N.Y., a corporation of New York No Drawing. Filed Sept. 3, 1963, Ser. No. 306,345

11 Claims. (Cl. 252--62.1)

This invention relates in general to electrostatography and in particular to developers for three color renditions by electrostatographic techniques.

Some define electrostatography as encompassing the entire field of forming and utilizing latent electrostatic charge patterns to record and reproduce patterns in visible form. This field was pioneered by Chester F. Carlson when he disclosed in U.S. Patent 2,297,691 the basic techniques of one major sector of the field referred to by some as electrophotography or, as it is more'familiarly known xerography. In the most commonly practiced form of xerography a photoconductive insulating layer is first given a uniform electrostatic charge over its entire surface and is then exposed to an image of activating electromagnetic radiation such as light which selectively dissipates the charge in illuminated areas of the photoconductive insulator, While charge in the non-illuminated areas is retained thus forming a latent electrostatic image. This latent electrostatic image may then be developed or made visible by the deposition of finely divided, electroscopic marking material on the surface of the photoconductive insulating layer, as a result of which the marking material conforms to the pattern of the latent electrostatic image. The visible image may then be utilized in a number of diverse ways. For example, the image may be viewed in situ on the photoconductive insulator, fixed in place on the photoconductive insulator or transferred to a second surface such as a sheet of paper and fixed in place thereon as desired, depending upon whether the photoconductive insulating layer is non-reusable as is the case with particulate zinc oxide binder film type xerographic plates or reusable as is the case with amorphous selenium. Hundreds of additional patents have issued in the field of xerography since the time of the original Carlson patent incorporating many improvements into the basic process and as a result of this development xerography is today, by a great margin, the largest commercial sector of electrostatography. The other broad general branch of electrostatography is generally referred to by some as electrography and it is con sidered distinct from the xerographic branch in that it does not employ a photoresponsive medium and an electromagnetic radiation im-ageto form its latentelectrostatic image. Electrography may generally be divided into broad sectors which are xeroprinting and electrographic or TESI'recor'ding. Xeropriuting may be said to be the electrostatic analog of ordinary printing. This process which is more fully described in U.S. Patent 2,576,047 to Schaffert, employs a xeroprinting plate made up of a pattern of insulating material which is generally on a conductive backing so that when the xeroprinting plate is charged as with a corona discharge electrode anelectrostatic charge pattern is retained only on the patterned insulating sections of the plate. This electrostatic image may then be developed with the same developing materials and techniques employed in developing xerographic images. Although the word xrography is also used in this art in as encompassing a way as electrostatography, the definitions given above will be used throughout in this instance.

Inelectrographic or TESI (an acronym stemming from the phrase Transfer of Electrostatic Images) recording, the electrostatic charge patterns conforming to the deice sired reproduction are formed on a uniform insulating layer by means of an electrical discharge between two or more electrodes on opposite sides of the insulating medium. By controlling the shapes, combinations and numbers of electrodes employed, charge patterns of almost any shape may be formed on the insulating medium. Again, image development is by the same techniques as in xerography. In another system of xeroprinting which is described, for example, in U.S. Patent 3,081,698 to Childress, a conductive screen with a plurality of apertures which define the image area to be reproduced is spaced opposite a conductive backing electrode and a potential is applied between this backing electrode and the screen such that when finely divided electrostatographic toner particles smaller than the apertures in the screen are applied to the surface of the screen opposite the backing electrode, the electrostatic field set up by the potential source causes the particles to move through the apertures in the screen to form a toner image on the backing electrode in the configuration of the apertures on the screen. Various surfaces may be interposed between the screen and the backing electrode so that the particle image may be intercepted and formed on such interposed surfaces. Regardless of the surface upon which the toner image is deposited, it may be fixed in place upon that surface or transferred to another surface and fixed thereon.

The common feature of all of these electrostatographic systems is that they employ the lines of force from an electric field to control the deposition of finely divided, marking material or toner on a surface, thus forming an image with the toner particles. Although all of these systems are used almost exclusively for black and white reproduction at the present time they are capable of forming images in other colors and combinations of colors. As with other color systems these electrostatographic color systems are generally based on trichromatic color synthesis of either the additive or subtractive color formation types. Thus, when electrostatographic systems are operated in full color, toner or developing particles of at least three different colors must be employed to synthesize any other desired color. As a rule, at least three color separation images are formed and combined in register with each other to form a colored reproduction of the original. Thus, in xeroprinting or electrographic recording at least three different latent electrostatic images must be formed, developed with ditferent colored toners and combined to form the final image. The same is true of color xerography where as described, for example, in U.S. Patent 2,962,374 to Dessauer, U.S. Patent 2,986,466 to Kaprelian, and U.S. Patent 3,057,720 to Hayford, at least three latent electrostatic images are formed by exposing a xerographic plate to different optical color separation images and each of these latent electrostatic images is developed with adifferent colored toner, after which the three toner images are combined to form the final image. In any of the systems described so far this combination of the three color toner images is generally made on a copy sheet such as paper, to which the images are permanently afiixed. The most common technique for fixing these toner images to the paper copy sheet is by employing a thermoplastic resin toner which includes a colorant and heat fusing the toner images to this copy sheet, although the images may also be fixed by other techniques known inthe art,such as subjecting them to a solvent vapor.

In general, the prior art color electrostatographic systems operate either by laying the color separation toner images one on top of another as described above, or by reserving small elemental contiguous areas for depositing toner particles of each color going to make up the composite color image as described, for example, in U.S. Patent 3,060,019 to Johnson. Not only does this second system require very elaborate precautions to insure that one image will be in proper registration with the other on the copy sheet, but it forms a rather crude final image, significantly reducing system resolution to the area in which three different color toner particles may be included. On the other hand, this second system does have the advantage that the toner particles need not be transparent and in fact are generally opaque so that certain inorganic pigments may be utilized in their fabrication. In the first system in which the powder images are superimposed, the toners must, at the same time, be quite transparent so that no one of the three toner color pairs will obscure the different colored toner images below it and yet each toner must have sufiicient color saturation and brightness to satisfy the colorimetric requirements for three color synthesis of natural color images. As might be well imagined, these requirements are virtually diametrically opposed and, as a matter of fact, no prior art colored electrostatogr-aphic toners have fully achieved both of these results. In addition, it is highly desirable that the color saturation of the three toners be sufficient and that they be of the proper hues so that the three colors go together to produce a deep black. This objective has been found to be virtually impossible of achievement in electrostatographic color reproduction systems as well as in many conventional color reproduction systems including full color printing, and even today these systems generally employ the superpositioning of four different colored images. The additional color used is black and requires the formation of a fourth image for the black with consequent additional apparatus and registration problems. This problem generally arises because if inorganic pigments are used as the coloring material either in printing inks or electrostatographic toners it is quite diflicult to achieve the proper color balance and saturation in only three different toners for use in color synthesis while still keeping the colors transparent. This problem arises because the range of colors available with inorganic pigments is relatively narrow and since they are for the most part themselves opaque, they generally impart opacity to the materials to which they are added even in relatively small amounts.

Although organic dyes have been suggested for use in colored xerographic toners because of the. wide range of colors in which these dyes are available, their use is not desirable because they are generally less lightfa-st than inorganic pigments and furthermore because when these electrostatographic toners are fixed to the substrate upon which the colored image is formed as by heat or solvent fusing, significant bleeding or spread out of the dyes is found to occur.

Now in accordance with the present invention, there is provided a new and improved type of colored electrostatographic toner made up of finely divided, transparent, resin particles containing pigments which are generally referred to in the art as organic dye pigments. These toners are provided in a system of three different transparent toners, each containing different organic dye pigments in the proper proportions rendering each of the toners of the proper color and saturation and sufliciently transparent so that when layers of the three toners are superposed they produce a deep, intense black. In addition, these toners have been found to be much more lightfast than dyed toners and to be very much more resistant to bleeding of color upon toner fusing than such dye toners. These organic dye pigmented resin particles' generally have a particle size of less than about 30 microns and usually have an average particle size ranging between about 4 to about microns, although both larger and smaller particles may be used depending upon their application. The particles are generally manufactured byuniformly blending the organic dye pigment in the resin and then dividing up this mixture.

Although substantially any transparent electroscopic resin may be utilized as the resin component of a toner it is preferable that resins which also have other desirable properties be utilized in this invention. Thus, for example, it is desirable that a resin be used which is a nontacky solid at room temperature so as to facilitate handling and use in the most common electrostatographic processes. It is also desirable that the resin be a thermoplastic with a melting point significantly above room temperature but below that at which ordinary paper tends to char so that once the toner image is formed on, or transferred to a paper copy sheet it may be fused in place thereon by subjecting it to heat. It is to be noted, however, that this is not absolutely necessary since higher melting point resins may be employed and fused to paper copy sheets by other techniques such as subjecting the paper copy sheet bearing the powder image to vapors of a solvent for the resin as described, for example in US. Patent 2,776,907 to Carlson. Of course, toners may be fused to other surfaces which may, because of their heat transfer and wetting characteristics, control the amount of heat required to fuse the toners to them. In addition, it is desirable that the toner resins have good triboelectric properties and be insulating enough to hold charge so that they may be used for development in various electrostatographic techniques including cascade development of latent electrostatographic images as described in US. Patent 2,618,552 to Wise and US. Patent 2,638,416 to Walkup and Wise, and other development techniques know in the art as well as for electrostatic powder image transfer described in U.S. Patent 2,576,047 to Schaifert and 2,626,865 to Mayo.

Various exemplary resins which may be utilized in the toner particles of this invention, and have the required properties include (1) a rosin modified phenol-formaldehyde resin containing about 5% to 45% polyvinyl butyral,

' the rosin modified phenol-formaldehyde being prepared using from about 1 to 8 parts rosin for each part of phenol-formaldehyde base and having a ring and ball melting point of about to C. as described more fully in US. Patent 2,753,308 to Landrigan; (2) a polystyrene or predominantly styrene or polystyrene based resin as extensively described, for example in US. Reissue Patent 25,136 to Carlson. This second type of resin may comprise polystyrene alone, in blends with other resins as more specifically described in US. Patent 2,788,288 to Rheinfrank and Jones or may be comprised of a copolymer of styrene and a methacrylate ester which may also include a plasticizer as described more fully in US. Patent 3,079,342 to Insalaco; and (3) an epoxy which is solid above room temperatures such as one of the Ep-ons available from Shell Chemical Company. All parts in the examples are by weight unless otherwise noted. The following exemplary electrostatographic toners were formulated for use in color reproduction systems that are predominantly of the subtractive type while some additive or pigment mixing may also be involved.

Example I A transparent yellow toner was prepared by first copolymerizing thirty-five parts by weight of n-butylmethacrylate with sixty-five parts of styrene. To 9.0 parts by weight of this copolymer there was added 1.0 parts by weight of a polyvinyl butyral resin obtained from the Bakelite Company under the trade name of Vinylite XYHL. To this resin mixture there was then added 1.0 part by weight of Benzidine Yellow OT. Benzidine Yellow OT is a trade name of E. I. du Font and Company for a toluidine of Hausa yellow which is a water insoluble azo compound listed in the color index as C.I. No. 21095, pigment yellow No. 14. Pigment yellow No. 14 is 3,3-dichloro-,4-bis(2"-acetyl 2"-azo-o-acetotoluidide)biphenyl. This mixture was prepared directly by blending the preformed copolymer, the Vinylite XYHL, and the Benzidine Yellow OT pigment directly on a rubber mill. After complete addition of the dye pigment the mixture was rubber milled thoroughly until the dye pigment was uniformly dispersed throughout the resin. About 60 passes through the mill were used for this blending. Since rubber milling of this material required preheating of the resin above its plastic point (about 220 F.) the completely mixed end product was first thoroughly cooled, broken in a Fitz mill and then finely divided in a jet pulverizer to yield the final toner powder composition having an average particle size in the range of about 5 microns with fairly good uniformity of particle size. T 0 test the suitability and effectiveness of this yellow, powdered toner composition it was deposited on an electrostatic latent image on an image bearing surface by mixing the toner in a two component cascade type developer as described in US. Patent 2,618,551 and cascading the mixture across the electrostatic latent image bearing surface. The image was developed by deposition of the powdered toner and the powder image was transferred to a paper transfer web by electrostatic transfer and then fused in place in a heated oven.

Examples II and III Two magenta toners were formulated each employing 9.0 parts by Weight of the copolymer and 1.0 part by weight of polyvinyl butyral as in the yellow toner of Example I. To the first of these toners there was added .75 part by weight of Monastral Red B, RT790D, a 2,9- dimethylquinacridone dye pigment believed to be produced according to Example V of US. Patent 3,085,023 to Ehrich. The second magenta toner was prepared by adding .75 part by weight of Rhodamine Y, RT6l2D, a phosphotungstomolybdic lake of xanthene dye pigment, color index No. 45160 color index pigment red No. 81. In the formulation of each of these magenta toners the pigment and resin blending, as well as the dividing of the blend into small particles, followed the same procedure as that described in connection with the yellow toner in Example I. These toners were also tested for their xerographic properties in the same manner as the yellow toner of Example I and were found to be highly acceptable.

Example IV A cyan toner was formulated employing 3357 parts by weight to the copolymer and 373 parts by weight of the polyvinyl butyral of the same types employed in Example I above. To this resin there was added 91 parts by weight of Monastral Blue BT279D, a copper phthalocyanine dye pigment (pigment blue 15, color index No. 74160) available from E. I. du Pont and Company and in addition there was added 4 parts by weight of Benzidine Yellow OT of the same type employed in the yellow toner described in Example I above,

All ofthe toners described above were tested both individually and in combination for the production of natural full color images by electrostatographic techniques. Results indicated that the toners formulated according to the examples described above had excellent electrical properties, producing very good images when employed in xerographic development in a cascade type developing mixture. It was also found that once the toner im-ages had been formed on the surface of a photoconductive insulating layer by xerographic techniques that the toner particle image could be easily transferred from this surface to a paper copy sheet by electrostatic transfer as described in the above referenced U.S'. Patent 2,576,- 047 to Schaffert as well as by other transfer techniques well known in the art. In addition, toner particle images formed from the toners described in Examples I through IV above were tested with regard to their fusing properties. Toner images formed on a selenium xerographic plate were transferred to paper sheets by electrostatic transfer and were fused to these sheets utilizing both heat fusing and solvent vapor. fusing techniques. Although the thermoplastic resins in the toners were softened sufficiently so that they were very well fused to the paper copy sheets, in both these techniques no bleeding of the colors was discernible so that resolution remained-high even Where the three toners were used in combination to produce full color images. In addition to this lack of bleeding upon fixing, it was found that the toners were substantially color fast under ordinary storage conditions and were even light fast so that they need not necessarily be stored in closed light-tight containers as is frequently the case when certain ordinary dyes are used as colorants in toners of this type. These toners were also found to satisfy the colorimetric requirements needed for three color process reproductions. As stated above their colors are yellow, cyan, and magenta and their mixtures in pairs produce blue, red and green of the desired shades, saturation and brightness for good three color reproduction by electrostatographic techniques. Furthermore, it was found that the three toners together produce a deep black in sharp contrast to ordinary color letter press or offset printing inks and other colored toners where it is not possible to obtain a deep black and the grays are all brownish so that a fourth plate for the black is generally utilized. Although two magenta toners are described the one employing the quinacridone pigment was found to be generally superior. The toners described above for electrostatographic use have been found to eliminate the necessity for this type of black printer and are thus significantly better than commercially available rotogravure inks as far as their colorimetric properties are concerned. It is thus seen that the electrostatographic toners of this invention take electrostatographic color reproduction techniques one step beyond commercially utilized color reproduction techniques because these toners eliminate the need for black printers in the system. In addition, it has been found that these toners are, at the same time, transparent enough and saturated enough in their own colors to allow for the synthesis of any color with various combinations of the toners by superimposing toner images made from color separation images. Previously it was generally believed that this unique combination of properties was virtually impossible to achieve in stably colored xerographic toners because when the toners were sufficiently saturated they became so opaque as to obscure underlying layers.

Although specific pigment-resin combinations are given as toner formulations above, it is to be recognized that any substantially transparent resin having the proper electroscopic properties for use in electrostatographic processes may be utilized in the toner formulations. Even though it is preferable that these resins be thermoplastic, or unset thermosetting resins so that they may be fused to the copy sheet by the application of heat, this property is not absolutely necessary to the resins since they may be fused by other techniques including the solvent vapor technique described above. The pigment to resin ratio for each of the toners described above, is not absolutely 'critical and may vary .by small amounts in either direction than 6% cannot be made in the cyan. Furthermore, the

pigment to resin ratio may vary quite widely depending upon the saturation and transparency of the particular pigments employed. Thus it is seen in the examples that with the yellow toner the pigment to resin ratio is 1 to 10 while in the magenta toners the pigment to resin ratio is .75 to 10 and in the cyan toner the pigment to resin ratio is l to 40 because the magenta pigments are slightly more saturated than the yellow pigments and the Monastral Blue pigment employed in the cyan toner is grossly more saturated than either the magenta or the yellow pigments. Because of this lower pigment to resin ratio and in addition, because the cyan and magenta pigments are in and of themselves more transparent than the yellow pigment it is preferable that the yellow toner image be laid down on the copy sheet first, followed by the magenta and cyan toner images in that order if the toners are employed in a system which utilizes three color synthesis by superimposing these layers. It is to be understood, of course, that this is only a preferred order for laying down the powder images on the final copy sheet because although the order of transparency of the toners is cyan, magenta, and yellow, this is only a relative order of transparency and in fact, all three of the tone-rs are highly transparent as compared, for example, with a toner employing an inorganic pigment such as zinc oxide, titanium dioxide, carbon black or lead sulphate, and thus any order of laying down the diiferent colored toner images is acceptable for most purposes. All opaque materials such as inorganic pigments and any other mate-rials which impart opacity are to be avoided in the formulation of the toners of this invention. Of course, where the three colored toners are employed to produce transparencies, the order of laying down of the three color tone-r images is immaterial.

The advantages, examples, and description of the invention presented above are only intended as illustrative and are not intended in any way to limit the invention which is set forth in the following claims.

What is claimed is:

1. An electrostatographic toner consisting essentially of finely-divided particles composed of a substantially transparent electroscopic resin containing from about .92 to about 1.08 parts by weight of 3,3-dichloro, 4-bis(2"- acetyl-2"-azo-o-acetotoluidine) biphenyl per 10 parts by weight of the resin.

2. A toner according to claim 1 including about 1 part by weight of said 3,3-dichloro-4-bis(2"-acetyl-2-azoo-acetotoluidide biphenyl.

3. An electrostatographic toner consisting essentially of finely-divided particles composed of a substantially transparent electroscopic resin containing from about .69 to about .81 part by weight of a magenta 2,9-dimethyl-quinac-ridone dye pigment per 10 parts by weight of the resin.

4. A toner according to claim 3 including about .75 part by weight of said magenta pigment.

5. An electrostatographic toner consisting essentially of finely-divided particles composed of a substantially transparent electroscopic resin containing from about .69 to .81 part by weight of the phosphotungstomolybdic acid lake of xanthene magenta dye pigment per 10 parts by weight of the resin.

6. A toner according to claim 5 including about .75

part by weight of said magenta pigment.

7. An electrostatographic toner consisting essentially of finely-divided particles composed of a substantially transparent electroscopic resin containing from about 85.5

to about 96.5 parts by weight of a blue copper phthalocyanine dye pigment and about 4 parts by weight of 3,3- dichloro,.-4' bis (2"-acety1 2" azo-o-acetotoluidine)biphenyl per 3730 parts by weight of the resin.

8., A toner according to claim 7 including about 91 parts by weight of said blue copper phthalocyanine pigment.

9. A novel toner to be used in combination with two other electrostatographic colored toners for the synthesis of images in full, natural color by the substractive process, one of said two other colored toners being made up of particles consisting of a substantially transparent electroscopic resin containing color stable organic dye pigments in the ratio of 1 part by weight of 3,3'-dichloro-4- bis(2"-acetyl 2" azo-o-acetotoluidide)biphenyl and 10 parts by weight of the resin for the yellow toner, the other of said colored toners being made up of finely divided particles consisting of a substantially transparent electroscopic resin containing color stable organic dye pigments in the ratio of about .75 part by Weight of a magenta 2,9-dimethylquinacridone linear quinacridone dye pigment to about 10 parts by weight of the resin for the magenta tone-r and said novel toner comprising finely divided particles consisting of a substantially transparent electroscopic resin containing color stable organic dye pigment in the ratio of about 91 parts by Weight of copper phthalocyanine dye pigment, about 4 parts by Weight of 3,3'-dichloro-,4'-bis(2"-acety1-2"-azo-o-acetotoluidide) biphenyl to about 3730 parts 'by weight of the resin for the cyan toner.

10. A novel toner to be used in combination with two other electrostatographic colored toners for the synthesis of images in full natural color by the subtractive process, one of said two other colored toners being made up of particles consisting of a substantially transparent, electroscopic resin containing color stable organic dye pigments in the ratio of 1 part by weight of 3,3-dichloro,-4-bis (2"-acetyl-2"-azo-o-acetotoluidide)biphenyl and 10 parts by weight of the resin to make a yellow toner, the other of said colored toners being made up of finely divided particles consisting of a substantially transparent, electroscopic resin containing color stable organic dye pigments in the ratio of about 91 parts by weight of copper phthalocyanine dye pigment, about 4 parts by weight of 3,3-dichloro-,4'-bis(2"-acetyl 2" azo o acetotoluidide)bi phenyl to about 3730 parts by weight of the resin to make a cyan toner, said novel toner comprising finely divided particles consisting of a substantially transparent, electroscopic resin containing a color stable organic dye pigment in the ratio of about .75 part by weight of a magenta 2,9-dimethylquinacridone dye pigment to about 10 parts by weight of the resin.

11. A novel toner to be used in combination with two other electrostatographic colored toners for the synthesis of images in full natural color by the subtractive process, one of said two other toners being made up of particles consisting of a substantially transparent, electroscopic resin containing a color stable organic dye pigment in the ratio of about .75 part by weight of a magenta 2,9- dimethylquinacridone dye pigment to about 10- parts by weight of the resin, the other of said colored toners being made up of finely divided particles consisting of a substantially transparent, electroscopic resin containing color stable organic dye pigments in the ratio of about 91 parts by weight of copper phthalocyanine dye pigment, about 4 parts by weight of 3,3-dichloro-4'-bis(2"-acetyl-2- azo-o'acetotoluidide)biphenyl to about 3730 parts by weight of the resin, said novel toner comprising finely divided particles consisting of a substantially transparent, electroscopic resin containing color stable organic dye pigment in the ratio of 1 part by weight of 3,3'-dichloro-, 4'-bis(2"-acetyl-2"-azo-o-acetotoluidide)biphenyl and 10 parts by weight of the resin.

References Cited UNITED STATES PATENTS 2,892,794 6/1959 Insalaco 25262.1 3,049,077 8/1962 Damm 106-23 3,060,021 10/1962 Grieg 96-1 3,079,272 2/1963 Greig 25262.1 X

OTHER REFERENCES Tech. Manual of American Assoc. of Textile Colorists, p. D52 (1963).

Color Index, vol. 2, Soc. of Dyers and Colorists (1956), p. 2753.

LEON D. ROSDOL, Primary Examiner.

JULIUS GREENWALD, Examiner.

J. D. WELSH, Assistant Examiner.

Claims

9. A NOVEL TONER TO BE USED IN COMBINATION WITH TWO OTHER ELECTROSTATOGRAPHIC COLORED TONERS FOR TH SYNTHESIS OF IMGAES IN FULL, NATURAL COLOR BY TH SUBSTRACTIVE PROCESS, ONE OF SAID TWO OTHER COLORED TONERS BEING MADE UP OF PARTICLES CONSISTING OF A SUBSTANTIALLY TRANSPARENT ELECTROSCOPIC RESIN CONTAINING COLOR STABLE ORGANIC DYE PIGMENTS IN THE RATIO OF 1 PART BY WEIGHT OF 3,3'' -DICHLORO-4''BIS(2"-ACETYL-2"-AZO-O-ACETOTOLUIDIDE)BIPHENYL AND 10 PARTS BY WEIGHT OF THE RESIN FOR THE YELLOW TONER, THE OTHER OF SAID COLORED TONERS BEING MADE UP OF FINELY DIVIDED PARTICLES CONSISTING OF A SUBSTANTIALLY TRANSPARENT ELECTROSCOPIC RESIN CONTANING COLOR STABLE ORGANIC DYE PIGMENTS IN THE RATIO OF ABOUT .75 PART BY WEIGHT OF A MAGENTA 2,9-DIMETHYLQUNACRIDONE LINEAR QUINACRIDONE DYE PIGMENT TO ABOUT 10 PARTS BY WEIGHT OF THE RESIN FOR THE MAGENTA TONER AND SAID NOVEL TONER COMPRISING FINELY DIVIDED PARTICLES CONSISTING OF A SUBSTANTIALLY TRANSPARENT ELECTROSCOPIC RESIN CONTAINING COLOR STABLE ORGANIC DYE PIGMENT IN THE RATIO OF ABOUT 91 PARTS BY WEIGHT OF COPPER PHTHALOCYANINE DYE PIGMENT, ABOUT 4 PARTS BY WEIGHT OF 3,3''-DICHLORO-,4''-BIS(2"-ACETYL-2"-AZO-O-ACETOTOLUIDIDE) BIPHENYL TO ABOUT 3730 PARTS BY WEIGHT OF THE RESIN FOR THE CYAN TONER.