DE1153769C2 - Process for the production, renewal and printing of xerographically produced hectographic printing forms - Google Patents

Description

a) The printing form consists, in a manner known per se, of thin, flexible, translucent Material with a translucent semiconductor layer.

b) The spinning form is labeled on the non-layered side with a carbon paper tape or sheet.

c) The cargo is unloaded at the places where there is no written or image Illumination of the printing form from the non-layered side.

2. The method according to claim 1, characterized in that with a semiconductor layer provided translucent printing form, which is made of alcohol-soluble Dyes or dye components existing print image of a certain Color, e.g. purple, has been recharged after fixing the print image and the charge is erased at the non-image areas by x-raying the printing form film and then an insulating powder with the opposite charge to the printing form is also applied to the image areas is applied, then the printing form is reloaded and the original of the other color is photographed on the printing form and then the printing form with a different colored, z. B. red, alcohol-soluble dye or dye components is developed and fixed, the insulating powder being held in such a way that it does not melt or stick when it is fixed of the insulation powder is created on the first color, but the insulation powder with your second Paint powder again dusted before the second fixation or by opposing electrostatic Charge can be withdrawn again.

The invention relates to a method for producing xerographic printing forms with a Semiconductor layer on which, after charging, a latent one through differentiated exposure to light electrostatic image is generated and the printing form with one of alcohol-soluble dyes or such containing electrostatically charged medium, such as powder, liquid or paste, Developed in the image areas and then on thermal, chemical or mechanical Way is fixed. Such a method is the subject of the ÜSÄ patent specification, for example 2,624,652.

In order to generate an electrostatic image, it is generally known to provide the printing cylinder of a xerographic printing machine with a semiconductor layer, to generate a latent "electrostatic image" on this by means of differentiated exposure to light, and to develop and fix this,
ίο The facilities required for this represent a considerable effort, which, however, is too expensive and uneconomical for cases where only small numbers of copies are required. /

The invention is based on the object of remedying this situation and adding the known methods simplify and design economically.

This task is solved by combining the following features:

a) The printing form is made in known manner from ^v thin, flexible, material with a fluoroscopic durchleuchtungsfähigem capable semiconductor layer.

b) The printing form is inscribed on the non-layered side with a carbon paper tape or sheet.

c) The deletion of the cargo takes place in the places without writing or images by means of fluoroscopy of the printing form from the layer-free side.

Translucent material with a translucent Semiconductor layer is already by the French patent specification 1,176,381 as well as by the German Auslegeschrift i 060 713 became known, but it is from the French patent specification 1 176 381 no reference to the features essential to the invention of those listed under b) and c) Points to be taken, while in the German Auslegeschrift 1 060 713 recorded under b) Feature completely absent.

Compared to the state of the art, as e.g. by the German Aüslegeschrift 1 060713 and the French patent specification 1 176 381 is given, the invention offers the possibility for a direct on the uncoated side of the printing form by writing with a typewriter or by Hand-generated image by xerographic means a corresponding printable xerographic mirror image easy to create.

The method can advantageously be further developed by using a semiconductor layer provided translucent printing form, which is made of alcohol-soluble Dyes or dye components existing print image of a certain color, e.g. B. violet, has been charged again after fixing the print image and the charge is transferred to the non-image Make by X-raying the printing form film is deleted and then an insulation powder of opposite charge to the printing form is also applied to the image areas, then the The printing forme is charged again and the template of the other color is scanned onto the printing forme and the Printing form then with a different colored, e.g.

red, alcohol-soluble dye or dye components is developed and fixed, with the insulating powder is held in such a way that the insulation powder does not melt or stick when it is fixed

3. ■ ■■■ 4

the first color is created, but rather to dry the insulation powder and to powder it by grinding.

ver with the second colored powder before the second firing. Here are water-soluble dyes

xing again dusted or by counteracting by wrapping in wax against unintentional

set electrostatic charge again stripped off staining isolated. In the same way you can in place can be. , 5 or used together with the waxes resins

This makes it possible to forex be different colored, which are also in separate pulverized

to generate graphic images side by side. Form or in powdered form with the dye

As a binder for the semiconductor layer to be applied as developing powder. Therefor Printing form carrier foils come, for example, are particularly suitable: rosin, co-

Question: cellulose, cellulose ester, polyvinyl chloride, io lophoniumester (Staybelite), shellac, melamine,

Polyesters, polyamides, polycarbonates and others. modified phenol-formaldehyde resins, alkyd

All resins, silicone resins, polyvinyl chloride, polystyrene and others are suitable as coloring dyes.

alcohol-soluble dyes with great abundance, in order to loosen up the structure and improve it

which are suitable for duplication. Possibility of attack by the withdrawal liquid itself

Of course, water-insoluble 15 dye also come, especially after heating Bringing complex compounds of different dyes into fixation can produce gas Question or water-insoluble dyes, which agents are still added to the powder, e.g. B. Amdurch chemical compounds, water-insoluble, monium carbonate, ammonium carbamate, sodium power have been. carbonate.

As dye components, which are used in the 20 The above substances can be used as mixtures with organic Development of the electrostatic image is weak or acids are used to accelerate the generation of gas are colored, come into question: leuco bases,. be turned.

Bases or lactones of triphenylmethane and should not contain developing powder in dry to-diphenylmethane dyes. These will only be used through standing, but a developmental effect an acidic compound or a liquid or paste, the oxidizing agents described above can be used substances in suspensions and dispersions, e.g. transforms. Chlorinated hydrocarbons, carbon tetrachloride,

Furthermore, dyes with so-called indi-trichlorethylene can be used. The fast kator effect in question, in which on the chemically volatile solvent evaporates, so that the reaction path is a color change from a remaining developing medium or powder in a weak color to a strong color, the electrostatically charged image areas adhere to . B. Spiriodipyrane, Phenolphthalein, Thymolphtha- remains and on the electrostatically uncharged lein and other places easily, z. B. by shaking removed

Such dyes finally come into question, become can. However, liquids can also be used

which are used from several, preferably two color components, which are applied to the printing form.

components that are preferably not sprayed much themselves and that are already used during the spraying process.

or are not color releasing. , ses evaporate. There are for this in particular

The dyes can often be used alone such liquids, which consist of liquefied gas

be, however, according to the invention it is expedient and under the name Aerosol, Frigen

It is used to combine these with other substances or to be familiar with them. This is in this liquid

mix. For example, the coloring agents can be colored powder and the other colored powder constituents

can be mixed with powdered waxes, such as car-embedded.

nauba wax, stearin, oxide and montan wax. It used as an insulating powder to cover a first

however, it is also possible to use the waxes with the coloring electrostatically generated image, for. B. Glass dust

to dissolve the substance, to mix in the solution, to be used.

Claims (1)

Patent claims: 1. Process for the production of xerographic printing forms with a semiconductor layer, on which, after charging, a latent electrostatic image is generated through differentiated exposure to light, and the printing form with it an electrostatically charged one consisting of or containing alcohol-soluble dyes Medium, such as powder, liquid or paste, developed at the image areas and then is fixed by thermal, chemical or mechanical means, characterized by the combination of the following features: