DE1158987B - Process for the production of a flat printing form or an etch reserve from a latent electrostatic image - Google Patents

Description

The invention relates to a method for producing a printing form or an etching reserve from an electrostatic latent image residing on a surface of an object. That The method according to the invention is also used in particular for the production of stencil sheets and offset printing forms and the like

For example, it is known to use the electrostatic image bearing object directly as Make a master copy from which further copies can be made. This happens in one known method in that the electrostatic image by sputtering a resin on the photoconductive surface that carries the image, developed and colored by melting the applied Dust is fixed. Depending on the nature of the substance of the photoconductive layer, it can pass through during fixing Heating the pigment dust is evaporated, so that in the areas that do not carry any picture elements, the photoconductive surface has also disappeared. A piece of paper is then to be used to make copies use a solvent in which the dust particles are soluble. By pressing on In such a paper, particles of the melted fixation are loosened and transferred to the paper, so that there the picture is reproduced positively and visibly.

There are other methods of transferring an electrostatic image from a surface known to another, in which the electrostatic image is already developed or even fixed. Also, is a method of transferring an electrostatic image from the insulating front surface a film on the insulating front surface of a second film known, in which the two surfaces are mutually exclusive are approached so far and an electric field is so applied between the foils that the field causes a charge transfer between the two surfaces corresponding to the charge distribution.

While the first process requires the field to be made visible, im The last-mentioned method additionally uses an electric field, for which an additional Establishment is required.

With the method according to the invention, the Possibility to be created with the development of a positive and a negative image at the same time of the electrostatic image and the images obtained in this way for the production of a Flat printing form, a stencil sheet, an offset printing form or an etching reserve can be used close.

procedure

for producing a flat printing form

or an etch reserve from one

latent electrostatic image

Applicant:

The Commonwealth of Australia,
Melbourne (Australia)

Representative: Dipl.-Ing. E. Rathmann, patent attorney,
Frankfurt / M., Neue Mainzer Str. 40-42

Claimed priority:

Australia dated December 17, 1957 (no.33 890)

Kenneth Archibald Metcalfe, Graymore,

and Robert John Wright, Hectorville (Australia),

have been named as inventors

The process for producing a printing form or an etching reserve from a latent electrostatic An image that is on a surface of an object is made according to the invention in that a developer layer is applied to the surface of a second object, that the two surfaces are brought into electrostatic contact to develop the image so that the developer is selectively transferred from the surface of the second to that of the first article, and on each of the two surfaces as a positive or negative corresponding to the electrostatic image Image remains, and that one or the other object or both objects, if any is used as a printing form and / or as a mask (etch reserve) after a further treatment or will.

When the two objects, one of which is the electrostatic image and the other is the developer layer wear, are present, two surfaces with visible positive are created in two steps or negative images generated. So the first step is to bring the two together Surfaces and, as a second work step, the separation of these surfaces is necessary.

309 768/37

3 4

In an advantageous embodiment there is held. This step of the procedure is described with D

the method according to the invention in that the denotes.

Developer layer contains a liquid developer In the next step E , the film 1 is peeled off and the transfer of this layer to the latent block 8 and grazes the developer electrostatic image-bearing surface, as long as 5 of those surfaces on which the electroder developer is still liquid and before its carrier-static pattern on the photoconductive surface of the liquid has evaporated. The electrically insulating film with the corresponding marking or drawing of the carrier liquid has a volume resistance of. This leaves the pattern on the block 8 no less than 10 ¹⁰ ohms · cm and a dielectric back. Immediately thereafter, the etching can therefore begin tricity constant of less than 3. In this carrier io. Through the etching material, the zinc liquid is a pigment substance together with an od. The like. Attack at the points where the fixing substance for fixing the pigment in the winder has been lifted off. The developer is dispersed by evaporation of the carrier liquid. described below.

The further stages in the manufacturing process In the embodiment shown in FIG. 2, two drums 10 and 11 are naturally pressed against one another in the respective manner of the desired 15. Matched printing form. Therefore, if the printing forme each of the drums is provided with a handle 12 which is for offset printing, the developer can grasp a sheet. The drum 10 has to be assembled in such a way that it receives or repels the printing medium sheet 13, which subsequently forms the stencil, while the parts are in, while the drum 11 carries a film 14 from which the developer has been removed which have opposite effects to those that have a photoconductor 15 on their surface. Such a print, on which an electrostatic image is first applied in the sub-form, can be used directly with a printing ink or with reference to steps A and B of Fig. 1 in another medium, whereas shown manner is applied,
Then, if the printing form is to be etchable, the Ent- A developer roller 16 is a developer winder must be designed so that it is associated with a mask 25 container 17 and is in contact with forms, so that the printing form is then on the normal of the drum 10, so that in use, if paths can be etched or the developer can move the two drums 10 and 11 in the direction shown by the arrows in the case of a stencil made of wax, the stencil then using the prepared stencils 13 bent a coating from developer, which is allowed in a normal printing machine, namely 30 is applied uniformly by means of the roller 16, because of the removal of the pattern during the The developer is then in different ways formation of the printing element. lifted from the point of contact 18, in which the

The invention is pressed against the template 13 on the basis of the drawings on the film 14. By

an exemplary embodiment explained in more detail. It shows that a stencil 13 remains on

1 shows several schematic views from which the developer removed such surface parts

the application of the invention has been to the manufacture on which it is not desired. Of the

from printed pieces, and developer remains un-

Fig. 2 is a schematic view of a wax damaged so that it can act as a mask,

stencil making machine. Among the examples from developers working for

A film 1 in Fig. 1 has a photoconductive 4 ° can be used for the purposes mentioned above

Coating 2 and is charged by the following developer for the production of

Foil 1 between a base plate 3 and a number of printing forms according to the method in Fig. 1 as

is brought by points 4, between which a high has been shown to be suitable:

DC voltage is applied. By this arrangement the developer consists of 5 g of beeswax and the foil 1 is charged, which then takes its charge for 45 100 g of Shellite. The wax will remain in the solution for a reasonable amount of time, unless it is thinned by stirring immediately before use. This portion of the representation is dispersed. The developer is denoted by A during the term. use at a temperature not exceeding

In process step B , the film 1 is kept below 18.5 ° C.

An exposure device that has a patterned 50 Another type of developer consists of 5 g of card

Image on the photo surface 2 of the slide throws and nauba wax and 100 g of Shellite, the same

thereby the electrostatic pattern by means of derivation of temperature limitation applies.

those sections modified in which the light is used for the production of offset printing forms

falls on the photoconductor. A metal-suitable developer can be built up as follows:

basis 6 used. 55 chrome yellow 100g

The film now holds the electrostatic image Rhodene Lo'lOO 15 g

fixed, and the next step, labeled C, is Pentarol 20 15 ε

stands in the application of a developer coating kerosene 25 s

onto the surface by means of a developer roller 7

a zinc plate 8 or the like, which form the printing form 60 The base thus formed is based on the required

target. Grinded fineness according to the for

At the moment when the developer on the liquid development already known method.

Block or the pressure plate 8 has been applied, the base is then in the proportion of 5 g of the

the film 7 is placed over the block 8 and suspended by means of a base in 100 g of solvent. That

a roller 9 pressed down. This pre-65 solvent consists of 50 g of cyclohexane, 10 g

The first step is the photoconductive surface 2 of the sheet 1 in mineral turpentine, 20 g Freon 11 and 20 g Freon 113.

intimate contact with the surface of the block Freon 11 and Freon 113 are trade names

or printing plate 8 placed on which the developer for coolant. Freon 11 evaporates relatively quickly,

5 6

but Freon 113 is more viscous and has a higher process to subject, so that a proportionately

Boiling point. permanent pattern is obtained, which for the

This developer is not very sensitive to heat. Used to produce a large number of prints

If a trigger or ignition developer can be used.

should be, so a developer who is going for a 5 If on the other hand an etched type of printed matter If the charge value is more difficult to form than it is to create, the pressure can decrease Straight-ahead developer, the following recipe element can consist of a zinc plate or the like, which be turned. On its surface a thin layer of the Ent- A black paste and a trigger paste will be winder, which in turn will carry a in a solution such as follows: "> can be medium-dissolved wax or resin. In The black paste consists of: in this case, however, the pattern is in the zinc or Printing ink 15 g other plate in any known process

du ι i _t , inn _K "etched in after the surface with the electro-

Rhodene Lo / 100 15 g *? l w τ> -ν. · * J ^ * · ι,

ρ * ι? 0 15 2 static patterns in contact with the developer

K rosin ~ 25 e ¹ S to remove the developer from the selected

° Set the pressure element has been brought to

The trigger paste consists of: so that the printing form can be generated immediately.

Organic shot 120 g ^{for screen printing} & stencil duplication

Rhodene L6 / 100 15 ε using a wax sheet, the sieve or a

Pentarol ⁹ O 15 e * ° ^otherwise '8 ^e surface again with a wax

Kerosene " 25 e ° ^ ^er resin developer. This ent

The winder can then be sent to the selected

Each of these pastes will be removed to the desired con-places so that the other one is electrosistent ground to ensure that the static image bearing surface is applied. Particles of the printing ink and the organic shot 25 This creates a screen stencil or another evenly coated with Rhodene and Pentarol, the part can be used immediately for printing purposes, gained, with and without hardening the

Rhodene and Pentarol are the controlling and wax, resin or the like.

fixing substances. The Rhodene is normal in the foregoing, of course, that while

carrier solutions used exhibited a relatively insoluble 3 ° of the development of an electrostatic image Resin and therefore acts mainly as a controlling agent in this way a photographic positive and a negative substance, by extracting the printer's ink and organically. It is thus easily possible niches particles and give them a character- both one and the other of these two teristic surface charge issued by the elements as a ready-made means of printing to ver-charge des Rhodene is intended. Turn the Pentarol 20 35 over. In this way it is possible to get the picture on is a soluble resin, which develop during the de- part of the entanglement as a pressure element partially dissolves and should therefore be used as a fixative. It is, however, added matter acts when the carrier liquid finally indicates that the object of the invention evaporates is. especially for the production of a printing element. In use, 5 g of the black paste 40 are removed by removing part of a thin film and 2 g of the red paste with 10 g of mineral turpentine, the developer of the element itself. Of the which is preferably done with 50 g of Shellite and 40 g of developer in the desired places Freon 113 is offset, mixed. stripping and leaving the electrostatic image

When a triggered white developer uses a printing element with a pattern. the white paste can contain 75 g of zinc and 25 g of raw 45 while therefore carrying out the invention Contain linseed oil, while the trigger paste 70 g can be one of the surfaces used for barium sulfate and contains 30 g of raw linseed oil. The position of the final printing element is used Both pastes are ground again, and it should be noted that the basic advantage of Use 20 g of each paste in 50 g of petroleum, a process used in the manufacture of a printing element which is diluted with 50 g of Shellite, dispersed. 5 °, the basic step of which is the removal of In this case the crude linseed oil acts both as part of a thin film of the developer from the controlling as well as fixing substance for the surface by means of electrostatic means, Zinc oxide and barium sulfate. Because it is in the carrier, around the image, as it is, to form the printing fluid is relatively soluble, the element acts to leave behind, or what to create Oil, however, is mainly used as a fixing substance when the finished printing element is, for example, through equal to it to some extent to control hardening or etching, further treated the surface charge of the particles during the can.

Development serves. The developer can of course be resistant to

From the foregoing it can be seen that by the alkalis or acids, or simply from one Use of developers of the type described 60 consist of a substance that repels water or fat. It is a desired masking on the printing form or also possible that the developer with pigments can be built up on a stenciled arch or provided with other substances added to it, and that it is when the wax or resin supports the construction of a mask or itself is designed so that the printing ink or ink det- act as fixing or hardening elements neither absorbs nor repels, is possible immediately, if the soluble part of the developer after bar to print from such an element. It is used to apply the electrostatic image but depending on the type of substance it may be desirable to evaporate the pattern in the developer first the wax or resin od. The like. A hardening or otherwise has been removed.

In the same way, two types of developer can be used for special effects, where one is positive and the other is negative.

In this description, the carrier liquid of the developer, such as Shellite, kerosene, cyclohexane, turpentine oil, coolants and the like, is to be restricted to liquids that have a volume resistivity of not less than 10 ¹⁰ ohm · cm and a dielectric constant of not more than 3 having. The liquid should be evaporable to allow the settling of the pigment or carried particles, but the evaporation should be slow enough to allow transfer while contacting one element with the other.

The wax can be used on its own without pigment substances, and in a similar manner can in this respect a wax or oil can be used and deposited electrically, like these substances a charge have that allows their precipitation.

"Rhodene L 6/100" is a registered trademark of the Polymer Corporation Interstate Pty. Limited for a linseed oil-modified alkyd resin (oil length 52%, acid value 6 to 10, specific weight at 20 ° C 0.955 to 0.965).

"Pentarol 20" is a registered trademark of the Polymer Corporation Interstate Pty. Limited for a phenol-modified penta-erythriol resin ester (acid value 7 to 15, specific weight at 20 ° C 1.09, melting range 110 to 120 ° Q.

30th

Claims (9)

PATENT CLAIMS: 1. A method for producing a printing form or an etching reserve of a latent electrostatic image which is located on a surface of an object, characterized in that a developer layer is applied to the surface of a second object that the two surfaces to develop the image in electrical contact so that the developer is selectively transferred from the surface of the second to that of the first object and remains on each of the two surfaces as a positive or negative image corresponding to the electrostatic image, and that one or the other object or both Objects is or will be used as a printing form and / or mask (etching reserve), if appropriate after a further treatment. 2. The method according to claim 1, characterized in that a liquid developer is used which contains an electrically insulating carrier liquid with a volume resistivity of not less than 10 ¹⁰ ohm · cm and with a dielectric constant of less than 3, in which a pigment material together with a fixing substance is dispersed for fixing the pigment when the carrier liquid evaporates, and that the transfer of the developer from one surface to the other is carried out while the developer is still liquid and before its carrier liquid has evaporated. 3. The method according to claim 2, characterized in that a liquid developer is used which has a wax suspended in a carrier liquid and a carrier liquid having a volume resistivity of not less than 10 ¹⁰ ohm · cm and a dielectric constant of less than 3, and by Evaporation of the carrier liquid creates a wax pattern. 4. The method according to claim 2, characterized in that a liquid developer is used which contains a resin which ^{is suspended in a carrier liquid having a volume resistivity of not less than 10 10} ohm · cm and a dielectric constant of less than 3, and by Evaporation of the carrier liquid forms a resin image. 5. The method according to claim 2, characterized in that a liquid developer is used which contains an oil which ^{is suspended in a carrier liquid with a volume resistivity of not less than 10 10} ohms ■ cm and a dielectric constant of less than 3, and by Evaporation of the carrier liquid forms an oil image either as a printing element or as a mask. 6. The method according to claim 2, characterized in that a liquid developer is used which comprises a pigment substance coated with a resin which is at least partially soluble in the liquid in which it is suspended and as a suspending liquid an electrically insulating liquid having a volume resistivity of not less than 10 ¹⁰ ohm · cm and a dielectric constant of less than 3 is used, and a pigment image fixed by the resin is formed by evaporating the carrier liquid. 7. The method according to claim 2, characterized in that a liquid developer is used, the a carrier liquid with a volume resistivity of not less than 10 ¹⁰ ohm · cm and a dielectric constant of less than 3, a first pigment in the carrier liquid, which with a resin which is partially soluble in the carrier liquid has been coated beforehand, has a second pigment substance which is likewise previously coated with a resin which is partially soluble in the carrier liquid, and a pigment image fixed by the resin is produced by evaporation of the carrier liquid. 8. The method according to claim 2, characterized in that a liquid developer is used which contains a pigment substance previously coated with a phenol-modified penta-erythriol resin ester of a resin and in an electrically insulating liquid with a volume resistance of not less than 10 ¹⁰ ohms. cm and a dielectric constant of less than 3, and a pigment image fixed by the resin is formed by evaporation of the carrier liquid. 9. The method according to claim 2, characterized in that a liquid developer is used containing a pigment previously treated with a phenol-modified penta-erythriol resin ester a resin and coated with a linseed oil-modified alkyd resin of medium oil length and in an electrically insulating Liquid with a volume resistivity of not less than 10 ¹⁰ ohm · cm and a dielectric constant of less than 3, and a pigment image fixed by the resin is produced by evaporation of the carrier liquid. 10 Considered publications: German Auslegeschrift C 9414 IVa / 57. made known on 5 July 1956); U.S. Patent No. 2,297,691. 1 sheet of drawings