DE1472930A1 - Xerographic process - Google Patents

Description

PATENTANWÄL TE 25/17/34/45 ₇ STUTTGART 1?. · Ο!? ** · I? ⁶⁴ DR.-ING. WOLFF, BARTELS, DR. BRANDES long street si ^:

TELEPHONE: 276310 and 297295 TELEPHONE: 0722312

U72930

Reg.-Mr. 119

Eaatman Kod ^ k Company, 343 Otate Street, Rochester i> taat iiew York, United States of / onerika

Xerographic process

The invention relates to a xerographic hischea Procedure in which an electrostatic image is transformed into a visible one by treating with a liquid toner ίild is convicted.

The xerographic process can be electrostatic 1 image can be generated in different ways. So can for example, a photoconductive surface is charged and then exposed image by image. together is the charge in <en exposed! '' laugh "punched".

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In the known processes, the electrostatic image is developed by applying toner particles, ie solid particles, to the imagewise charged surface. The toner particles are applied to the imagewise charged surface in the form of a cloud of powder or in the form of a dispersion in an electrostatically inert liquid or a mixture of toner particles and larger inert particles. The real Tonun>: sr.ittel also exists in the "liquid Kntwicklungs" method rue solid, dispersed in a liquid, but not covet particles. The well-known processes also have one thing in common, even if the surface carrying the electrostatic picture is exposed to an accumulation of fine, strongly colored particles, which brings with it a number of linchpins.

Jo can use the (well-known) xerographic development process referred to as 30fu "dirty" procedures, Vv'eil the development by means of a powder or a dispersion of solid particles in a liquid leads to the formation of otcub or / erosolem, which the unrolling machine and pollute their surroundings, i ^ ine unsolicited Contamination of the development machines also occurs Use of a liquid, ink-like toner

In the known development processes, there is a further difficulty in keeping the toner particles finely distributed because, in all of these processes, granular 909832/1056

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and microscopically visible toner particles can be used. The distribution of the grain size in the developed image is available in all known processes in a direct relationship to the distribution (the grain size) in the development used accumulation of toner particles. The toner particles must be chosen carefully and carefully sieved to produce a fine distribution of particles { later they must be carefully handled in order to Prevent the fine particles from agglomerating.

The invention was therefore based on the object of a xerographic To create a method in which development by a toner deadener is avoided and in which all the difficulties that are on the kenfkeit and the due to non-uniform particle size of the toner particles, are omitted.

The problem posed was solved according to the invention by that on the electrostatic image from an electrically insulating, free of solid particles solution of an im Normal state solid in a volatile solvent existing toning agent is applied and the solvent is evaporated

i) The image development can be achieved by simply immersing a an electrostatic oil bearing surface in a ·

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Solution of the specified composition and then Removal from the solution or by simply tamponing the surface with such a reading. The solution itself consists of a solvent that itself electrically insulated with the dissolved substance and a dissolved substance. However, there is no solid in the solution present when applied as a layer over the electrostatic image. Once the solution with the surface comes into contact, development occurs instantaneously. Fixing is not required. All that is required is that Evaporation of the solvent. Unch the evaporation the solute remains in a solid form, distributed image-wise · The image-wise distribution can, as further below will be discussed in more detail, either an edge distribution or a "fixed surface" distribution.

The electrostatic image is usually on an organic one Photoconductor or embedded in a polymer Produces selenium or zinc oxide. When using zinc oxide, this can be made hydrophilic and it can be a hydrophobic, dissolved .itoff in the developer solution to be used. In such a process, an Lltho printing master is created, as it is in the German Patent application E 21 446 IIa / 57d described eats.

The method of the invention can be used with xerography Perform procedures used ihotoconductors.

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The developing method of the invention is based on the knowledge that a latent, electrostatic image coated with an insulating liquid produces a (thick or thin) bas-relief image in the coating. When the solvent has then evaporated, the originally dissolved otoff remains as the solid body forming the image. If the dissolved substance consists of a dye, the image is directly visible. If the solute consists of a polymer, the image is a relief image that can be colored, used for lithographic purposes or converted with a special reagent or with the photoconductor itself to form a visible image.

.The method of the invention is explained in more detail in the drawing, lie show

Pig. 1, 2 and 3 the method of the invention in the scheme, Figures 4 and 5 show a modified embodiment of the method the invention,

-ig. 6 shows a subsequent operation to be carried out in some embodiments of the invention.

Fig. 1 shows a photoconductive layer 10, the z.l ·. the end Zinc oxide embedded in a polymer and applied to a conductive carrier 11 made of paper, for example is. The face of the Jhotokonductors is deceptive a negative electrostatic image, since it is indicated by 12 in the figure.

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According to FIG. 2 , an electrically insulating solution 15 is applied to the charged surface of the layer IO. The solution is applied by dipping the sheet into the solution and pulling it out again, or by tamponing the surface of the layer 10 with the solution. The solution then immediately forms an iielief with raised surfaces 16 at the edges of the electrostatic image, i.e. adjacent to the edges of the charged surfaces, while practically no solution remains in the uncharged or discharged surfaces, although a thin layer 17 in these areas is shown.

This marginal development, i.e. the thickness of the developing Liquids that only occur in flees close to which there is a change in the surface charge, is similar to the hand development, as seen from xerography A known technique is to use toner particles carried by plastic or glass beads.

According to FIG. 5, the solvent of the solution is evaporated, the originally gel-like substance as a solid body 20 remains on the electrostatically charged surface of the photoconductor 10.

The solution 15 contains the dissolved wtoff either colored

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Compounds (dyes) or uncolored or colored polymeric compounds. All these connections have in common that they remain as solid bodies when the solvent is evaporated. bo istcba image visible immediately or it can continue be reinforced. If the solute consists of a polymer, this can be made visible by applying a suitable dye that is derived from the polymer absorbed and repelled by the zinc oxide, or vice versa.

Another embodiment of the invention can be used for developing a "clear liquid" that can be used at a temperature above room temperature, but still below the temperature at which an electrostatic image would be destroyed is a liquid. Bare Cooling the liquid to room temperature then forms a solid 20 on the charged surface.

In special cases, the polymer relief image can also can be viewed directly as a black and white picture, if a well-known Schlieren-Cptik is used, which by optical interference relief images as black and white images makes visible. By a suitable choice of strength of the relief image, the Schlieren-Cptik can be used to to produce only color images.

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As can be seen from Fig. 4, there is some difference between this and that in Pig. 2 embodiment shown in the presence of a conductive metal plate 26 adjacent the image to be developed. at such an arrangement, i.e. a conductor opposite the surface during evaporation of the solvent, The solution 25 sanieelt in and over each charged one Area as shown in Figure 27, rather than directly or straight at the edges of the charged areas, as further in Pig. "is violated, remains when the solvent evaporates Pub the solution a feetee with 28 on the surface of the photoconductor 10.

A "solid" image development is thus obtained. The relative There are advantages of feston pictures and round pictures known from common xerographic processes. i) The invention is not concerned with the chemical structure of the surface on which the electrostatic images are generated, except in those cases in which the formed fixed image 20 or 28 of Fig. 3 or Fig. 5 with the Surface material itself implemented τ / ird. However have the usual forms of xerography an.: hotokonduktoroberflache, why the drawings / forms of Invention show where the electrostatic image 12 is is on a photoconductive surface 10.

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The images 20 or 28 can be hydrophilic and the surface hydrophobic. They can be used for planographic printing. The images 20 or 28 can also be hydrophobic and the photoconductor 10 can be made hydrophilic by known methods. If the lust substances are hydrophilic, care must be taken to ensure that the lion does not become conductive, that the electrostatic image is destroyed, which could be the case if the water that may be attracted by the hydrophilic substance causes too high a conductivity. This danger is not too great, however, since the absorption of water by such solutions is slow, while the evaporation of the solvent is rapid.

"As shown in FIG. 6, a relief image 28 can be used for the purpose of To produce a visible image colored with a dye or reacted with a suitable reagent, where dye or rain «are applied by means of an EÜrote 29.

All of these embodiments of the invention have the Advantage of avoiding the use of solid particles in the toner solution. Rather, the featen particles become only formed in situ on the surface to which the clear solution is excited.

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According to the invention binds the most varied of solvents suitable for carrying out the procedure. Ea is merely Required that the solution have a specific resistance of at least 10 (> hra-cm and a dielectric constant of less than 3 has. Suitable solvents are, for example, hydrocarbons such as hexane, Heptane, isooctane, paper thinner, serous, mineral oils for medical purposes, toluene, xylene, or halogenated hydrocarbons such as carbon tetrachloride, freon Freon BP or iluorolube i'S-5 etc.

.Example 1

Image-wise exposure of a charged surface of a photoconductor made of zinc oxide in resin was used to produce a latent xerogrophic image. The surface was taned with a solution containing 5 g of poly-n-butyl methacrylate in 95 g of cyclohexane, before the picture was left to air dry. . ^v s v. a relief image of solid i ol / -n-butylir.eth?: crylate was obtained on the photoconductor, of which the reflected light was immediately visible and which looked extremely high-contrast when viewed through a streak optic.

Leiepiel 2

The photoconductor of Example 1 was through a organic Ihotokonuktor replaced, the?; us poly ~ "-vinylcarb?; zol existed, the same solution as in I Eisriel 1

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was described thinly on an electrostatic image, that on the surface of this organic photoconductor was generated. I.Y-eh of evaporation of the solvent v / a bas-relief image was obtained, that in reflected light or through <; ine. streak Optically was visible because the ίhotoconductor seibot trans p.- rent was

Example 3

jiin electrostatic. Was LIID, dae to eineiu) hotokonduktor ™ according to Example 1 produced a solution C, 5, '<azo CII Black Ϊ, in toluene and was further diluted with lil Uyclohexnn ratio was tamponed r.it. Ea was directly giving a color image.

Example 4

An electrostatic IiId, di = s on a photoconductor according to i ice; IeI 1 was generated, rait a 0.2.

Solution of i; honylthiocarbazon, in a ratio of 1: 1 (

was diluted with cyclohexane, triMosed. The Crrbazone Compound reacted with the zinc oxide and produced a permanent tichtbrrea, pink-colored image.

free game 5

An electrostatic egg produced on the described in Example 1 ihotfkonduktor was created with a

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tamponized solution containing 0.5 Ά Sudan Black BR in a colorless paint thinner. A color image of excellent quality was obtained by tamponing.

Example 6

An electrostatic image, which was generated on a photoconductor according to Example 1, was tamponized with a solution which contained 0.5 / » Hipol Black B in a mixture of a paint thinner and toluene in a ratio of 1: 3. f A color image of excellent quality was obtained through the padding,

Example 7

An electrostatic image, which was produced on an Ihotoconductor according to Example 1, was tamponized with a solution which contained 0.5 t> Aep Oil Black in a colorless paint thinner. A color image of excellent quality was obtained by tamponing.

The invention therefore uses clear and, in a preferred embodiment, colorless solutions for toning or developing an electrostatic image. With such uinero Ln tv / icklungsverfahren connected neither :: chmutzentwicklung still an annoyance of the operator. There are also no inconsistencies with regard to the agglomeration of toner particles in the toner.

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Claims (1)

Claims Äerogrnphiache3 method in which an electrostatic image is developed by treating with a liquid ^A onungBinittel into a visible image, dmiurch in daii on the electrostatic image a from an electrically insulating, free of solid particles solution of a solid in üorraaliiuotKnd body in a volatile solvent existing clay is applied and the solvent is evaporated 2 · The method according to claim 1, characterized in that drk ^! the evaporation of the solvent is carried out in the absence of an electrical conductor. 3 · The method according to claim 1, characterized in that da-i v, at the end of the evaporation of the solvent a grounded, electrical conductors arranged adjacent to the surface is. 4. Ancestors according to /, nopruch 1, characterized in that as i'oneinittel a dye solution is used 909832/1056 BATH ORIGINAL " ¹⁴ ~ U72930 5. The method according to claim 1, characterized in that tile toner is a solution of 8 organic polymers is used· 6. Verfohren according to claim 1, characterized in that dai ¹ ronungBinittel as a solution of a rest ^ ndteils is used a farbtildenden ■ etktion · 7. The method according Anojruch 6, characterized dr.Jurch, dal 'rls W toning agent a iöe ng Onea l'.ectandteiles fnrbbildencieii a reaction is used, the Tait: inkoxjd as Heakticnepartner in Heaktio: i occurs. Method according to / no ^ ruch G _9, characterized in that the ζν, '- ite concentration required to carry out the color-forming' eckion 'is applied after the lönun has evaporated. 909832/1056 BAD original