DE1219329B - Electrophotographic process for the production of electrolytically developable images - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

EDITORIAL

Int. α .:

G03g

German class: 57 e-1/32

Number: 1 219 329

File number: M 44688IX a / 57 e

Filing date: March 17, 1960

Opening day: June 16, 1966

The invention relates to an electrophotographic process with electrolytic development.

It is known, on the exposed image parts of a copy material with a photoconductive and a electrically conductive layer to electrolytically deposit a metal or other material. Since the photoconductive layer is known to have a rectifying effect, d. H. the Stromüuß practically Allowed only in one direction, in these known electrolytic development processes, the electrically conductive layer, which is usually the electrically conductive layer carrier, always connected as a cathode will. If the electrically conductive layer is connected as the anode, the electrical resistance is the photoconductive layer very large even in moist, exposed parts of the image.

Because of this rectifying effect of the photoconductive layers was in these known processes the development is limited to the use of materials that are cathodically reducible are. Anodically oxidizable materials and those with a negative charge could therefore not be used will.

The object of the invention is to provide an electrophotographic process for the production of electrolytically developable materials To indicate pictures in which anodically oxidizable materials are used as developer substances can be used.

The object of the invention is based on an electrophotographic method of manufacture electrolytically developable images and is characterized in that an electrically conductive Layer and a photoconductive layer comprising copy material exposed imagewise, then as a cathode in the electrolysis of a solution containing an electrolytically reducible metal ion with selective deposition of free metal on the exposed parts of the copy material and then as an anode in the electrolysis of a solution that changes due to anodic oxidation or Emulsion is used.

The rectifying effect is applied to the image parts of the photoconductive layer that are covered with free metal canceled, d. H. passage of current in both directions is permitted. When the polarity of the electrodes is reversed be, d. i.e., when the electrically conductive layer is used as an anode, it can be applied to the with Metal-covered parts of an image are electrolytically developed using an anode process.

The copying material contains an electrically conductive layer, which can also be designed as a layer carrier. As such, metal foils and sheets are used for electrophotographic processes
Production of electrolytically developable images

Applicant:

Minnesota Mining and Manufacturing Company. St. Paul, Minn. (V. St. A.)

Representative:

Dr.-Ing. H. Ruschke, patent attorney,

Berlin 33, Auguste-Viktoria-Str. 65

Named as inventor:

Byron W. Neher, St. Croix, Wis. (V. St. A.)

Claimed priority:

V. St. v. America June 15, 1959 (820 254)

Aluminum, chrome, nickel or copper are suitable. The electrically conductive layer can be on a non-conductive Layer carrier, ζ. Β. be applied by vapor deposition. When the copying material into the electrolyte solution is immersed, the electrically conductive layer must be insulated from the electrolyte solution be by z. B. a non-conductive coating is applied.

A photoconductive layer is arranged on this electrically conductive layer and has a light conductivity of at least 10 ~ ⁷ reciprocal ohms / cm and a dark conductivity of not more than V20 of the light conductivity. It contains a binder and a photoconductor. Water-resistant, flexible polymers can be used as binders, provided that they are light in color and do not reduce the photoconductivity of the photoconductor. Such polymers include a mixed polymer of butadiene and styrene in a weight ratio of 30:70, polystyrene, chlorinated rubber, rubber hydrochloride, polyvinylidene chloride, nitrocellulose, polyvinyl butyral and silicones. Polymers that are dissolved or softened by water, have a dark color, are insoluble in conventional solvents, react with the photoconductor or slightly moisten it are unsuitable. Polyvinyl alcohol, polyacrylic acid, shellac and sodium carboxymethyl cellulose are therefore not used as binders. The weight ratio of binder to photoconductor is 1:10 to 1: 1, preferably 1: 5 to 1: 2.

609 579/201

Zinc oxide, cadmium sulfide, zinc sulfide or mixtures of these photoconductors are suitable as photoconductors. Zinc oxide is preferably used.

In order to increase the sensitivity of the photoconductive layers in certain areas of the In the spectrum, they can be mixed with dyes such as acridine orange, fluorescein, eosin Y, or rose bengal To be sensitized to methylene blue. Any reducible metal ion can be used as an electrolytically reducible metal ion inorganic or oxganische metal salt, e.g. B. silver nitrate, nickel chloride or copper sulfate is used will. The not yet reduced metal salt can also be in or on the photoconductive layer arranged and reduced in situ by electrolysis.

Serving as changing solutions used in anodic oxidation Solutions that change their color when oxidized. Preferably the solution is a vat dye used in leuco form. If z. B. Indigo white in contact with those covered with metal Image parts of the photoconductive layer is brought, the indig white becomes the insoluble, colored one Indigo oxidizes. The indigo image proves to be permanent and only fades very slowly, what probably due to the oxidation of indigo white when exposed to air. the Vat dyes in leuco form can be incorporated into the electrolyte solution or added to the before electrolysis photoconductive layer can be applied with the metal image.

. Serve as other changing solutions used in anodic oxidation Solutions with colored anions. Preferably, a solution with colored anions of an acidic Dye used.

During electrolysis, the colored anions of the acidic dye migrate to those covered with metal Parts of the image and are deposited there as a dye. The dyes are usually in the form of a sulfonic acid salt, usually the sodium salt Trade. Examples of such dyes are: naphtho yellow (C. J. No. 9), Fast Red (C. J. No. 176), Crocein Scarlet (C. J. No. 277), Naphthol Green (C. J. No. 5), Mool Green (C. J. No. 737), Erio Fast Fuchsine BL (CJ. No. 758), Solway Blue SES (CJ. No. 1053), Asocarmine (CJ. No. 828) or Quinoline Yellow (CJ. No. 801). Even if not with metal A little dye is often deposited on the covered parts of the picture, but the color is much more intense on the parts of the picture covered with metal. The contrast can by suitable choice of the colored anion, the concentration of the colored anion in the electrolyte solution, and the electrolysis conditions, e.g. B. the electrolysis time can be easily regulated.

In the case of anodic oxidation, part of the metal image can be oxidized, so that the current flows is decreased. However, this stops the deposition of the dye is not significantly affected.

According to the invention, the anodic oxidation can also be carried out with a changing emulsion.

An emulsion with negatively charged polymers is preferably used as the changing emulsion Used droplets. The polymer droplets can be colored or not colored and made of polyethylene, Polypropylene, polytetrafluoroethylene, synthetic rubber, polyvinyl acetate, polystyrene, a Mixed polymer of butadiene and styrene, of rubber, Polyvinylidene chloride, or a hydrosol from Aniline Blue (C. J. No ....) Or Indigo. Such emulsions are also called latices.

In the case of anodic oxidation, the negatively charged polymer droplets are deposited on those with metal covered image parts of the photoconductive layer deposited. When the negatively charged droplets

ίο consist of materials that, in contrast to hydrophilic photoconductive layer are hydrophobic and therefore ink-receptive, one obtains a Flat printing form with which excellent printed images can be produced. It can also be expedient be to incorporate fillers into the polymers that make up the droplets. Suitable fillers are pigments, carbon black or silica.

The inventive method is achieved that in contrast to the conventional electrolytic development process many oxidizable Materials can be used that carry a negative charge and are therefore deposited anodically can be.

example 1

A copy material with a 0.13 mm thick aluminum base and a zinc oxide binder layer (Weight ratio 10: 1) was 15 seconds with a 100 watt light source, with the a microfilm positive was projected onto the photoconductive layer, exposed. The exposed photoconductive Layer was then made with a solution of 10 percent by weight nickel chloride and 5 percent by weight Sodium thiosulfate is brought into contact and maintained at a potential of 30 to Electrolytically developed 40 volts with direct current, the substrate with the negative pole of the Connected to the power source and protected its exposed surface with a plastic cover was. After 15 seconds, the electrolysis was interrupted and the copying material was rinsed with water. A negative nickel image based on the light image was obtained.

The copy material was in a 1 weight percent Brought aqueous polyethylene latex [melting point 100.6 to 105 ° C, penetration (100 g, 5 seconds, 25 ° C) 3 to 6, acid number 14 to 17, color less than 1 on the national scale Petroleum Association]. After the copy material is connected as an anode and the exposed layer support made of aluminum had been provided with a plastic coating, became the polyethylene latex electrolyzed at a potential of 30 to 40 volts for 15 seconds. The polyethylene was on the exposed with metal-covered image parts deposited, producing a hydrophobic polyethylene image became. When used as a planographic printing form, printed images were obtained that were negative with respect to the photograph.

Example 2

A nickel image was made according to that described in Example 1 Process made. After the substrate has been connected to the positive pole of a voltage source of 30 to 40 volts, was with a sponge containing a dilute aqueous solution of p-aminodiethylaniline, p-nitrobene

containing cyanide and sodium sulfite and connected to the negative pole of the voltage source was, slowly wiped over the nickel picture. It got through on the parts of the picture covered with nickel Oxidation of the p-amino diethylaniline and coupling with the p-nitrobenzyl cyanide create a purple dye image obtain. The nickel image was slowly removed by oxidation during the electrolysis, see above that an excellent purple negative image was obtained.

If the coupling component a-naphthol or Ethyl acetoacetate are used, the images obtained are cyan blue and yellow, respectively. Instead of p-Aminodiethylenaniline can also use pyrogallol will.

Claims (6)

Patent claims: 1. Electrophotographic process for the production of electrolytically developable images, characterized in that one is an electrically conductive layer and one is photoconductive Layer having copying material exposed imagewise, then as cathode in the electrolysis a solution containing an electrolytically reducible metal ion under selective Deposition of free metal on the exposed parts of the copy material and then as an anode in the electrolysis of a solution that changes due to anodic oxidation or emulsion is used. 2. The method according to claim 1, characterized in that a photoconductive layer with zinc oxide is used as a photoconductor. 3. The method according to claim 1, characterized in that the changing solution the solution of a vat dye in leuco form is used. 4. The method according to claim 1, characterized in that as a changing emulsion an emulsion with negatively charged polymeric droplets is used. 5. The method according to claim 1, characterized in that the changing solution a solution with colored anions is used. 6. The method according to claim 5, characterized in that the changing solution a solution with colored anions of an acidic dye is used. 609 579/201 6.66 © Bundesdruckerei Berlin