DE453705C - Process for the production of a grainless printing surface which can be used for collotype printing or light glue printing from an invisible structure contained in a silver colloid layer - Google Patents

Description

GERMAN EMPIRE

ISSUED ON
DECEMBER 16, 1927

REICH PATENT OFFICE

PATENT LETTERING

CLASS 57d GROUP

Patented in the German Empire on September 7, 1926.

In the method used up to now for the production of light or. Light glue (collotype) Printing areas, either directly using gelatin treated with bichromate or by transforming silver images into a printing surface by means of a bichromate 0. The like. A bath that hardens the gelatin in the presence of the silver image is usually a Pressure grain generated.

With the usual collotype or light glue printing, in which the hardened image is obtained by exposing a treated with a bichromate salt Gelatine is formed, a large amount of the used gelatine is attacked and there is considerable network formation instead, which results from the disintegration of the gelatin into granular pieces. In a similar way when a silver picture in gelatin is treated with oxidizing agents, the hardened gelatin adjacent to silver, and in the processing of ordinary photographic Positives or negatives, where the developed silver image is a large part of the emulsion, results in the Disintegration of the particles is so great that a noticeable grain size occurs and, if the Gelatine is treated with chemical substances that can harden the gelatine, this hardening effect causes the gelatin formation to disintegrate, resulting in the state known as network formation. Furthermore, if the silver is removed by a subsequent bath in a solution of sub-sulfurous acid Soda is also removed, the gelatine becomes even more porous and the network formation is greater. Similar behavior results from the use of other colloidal substances.

The purpose of the invention is to make a grainless image from a silver containing image Produce printing surface that is suitable for collotype printing.

In the method for producing a printing surface according to the invention The image to be hardened is produced by a special development process, which in the immediate This is in contrast to the usual process for the production of photographic transparencies. At. this will be the Development carried out in such a way that strong, hard, i.e. high-contrast images in the Transparency, that is, arise in light falling through. In contrast, according to the invention the development of an image which is suitable for the ordinary photographic process,

abo is unusable for viewing or for projecting purposes due to its softness or dullness, i.e. due to the lack of density and depth of the image. The new process also produces images without internal reactions, ie without those within the gelatin, such as would result from adding excessive amounts of agents to the developer, which retard the development. ■ ' ■■ · ■ i, _, - ■ "

According to the invention, the "development of the exposed plate" or of the film, which therefore carries the invisible image, is carried out by means of a developer which acts on all: silver parts of the colloid layer proportional to the strength: the exposure that has fallen on each silver particle) however, the "effect", "* is so weak or matt that it produces an extremely soft and thin image, the j-ny density. and depth ■ missing, .- ⁱ and ^that: of small quantities of reduced Silber-- is ,.; the im.-colloid;! suspended; is held, whereupon the .colloid.in the presence of the silver "chemically adhered'wTrdC" *

That. The developed silver image is then expediently fixed and washed in the usual way, and then the film is subjected to chemical hardening, which consists in hardening the colloid in the ratio of the image tones ^{: for} this purpose the plate or the film can be treated while maintaining the silver image in the colloid ... The plate or the film is then washed and then only needs to be treated in the usual way like an otherwise used one 'Lichtdruckfjiiche,, um, sie, zum., "Qr.yck. · By means of bold suitable to .m.acheni. Because the very thin image produced by means of the development process according to the invention contains only very small traces of reduced silver. will, only; a small part of the colloid is taken up by the image and, as a result, the chemical hardening process (which hardens the colloid adjacent to the silver particles) leaves the bulk of the emulsion unchanged, with the result that the network structure. very little and consequently also <a minimum of granular particles is present. ,. ·. . .

Another very, important one. Advantage,; the, -self-off the development according to the invention. dation results, is, that · that the thin, or faint silver image can be preserved after it has served its first purpose, the ver- _ bond with oxidizing. Means for hardening the neighboring. Colloid, has served, with the result that a great cohesion of the colloidal .; Particle is obtained ^ which is still to a greater extent prevents the disintegration of the particles.

A picture of the weakness or softness as shown in the method according to the Invention necessary is achieved by using a conventional photographic developer by using this developer has been diluted with water more than usual. Accordingly, "for example, a developer is taken who twelve ■ to, twenty times as much diluted, than it is used in ordinary photographic processes. In this way ■ the developer effect is inhibited, so only very small traces or particles reduced silver and the otherwise subsequent reactions in the gelatine to be avoided "during" development.

A suitable developer under the

attsseteungi that- ^; he ^ in the above-given

Is diluted in a way that is 'amidol' (diamidophenal and dihydrochlo-

_; rid..C _Ä H _? .N ₂ 9 ^ HCl) ₁ contains. ...

An "important advantage of the invention is its use in the production of the printing surface of conventional commercial photographic plates or films. However, other similar printing areas can also be "used" for certain applications .; z. B. "a pressure surface, which is formed by cladding a base plate made of glass, metal or other material that does not, in general, .to receiving a gelatin: - ,. .Silber-, _Br; otnidemulsion who used the, ..,. in which case: an .intermediate or underlayer. is not. applied to the base area. .

.In. the main thing is, the procedure after. Invention with a. ordinary, commercially available plate or. a ■ · film that, under one; photographic. IS negative: exposed; be, .executed ... let it be however .notes ,,. that also, a negative. Gelatin silver picture, with, -like. Success to one Printing surface can be processed like a positive picture .. The ..- application.der Invention-110 dung. in this way. in .many cases prove to be very useful, e.g. B. \ yenn requires wifd, white letters or characters. · on a dark: ground, from a .. ge. homely copy. to make, those in black on. white paper .is,. ; ·. . , Tn 'one. practical embodiment the; invention becomes a plate or a film, expedient, such as a copy under a. photographic. Negative, is exposed, na.ch of the development in dex .above described.n..W.eise fixed, for example ... in ... one.

Bath made from sodium hyposulfur acid (fixer soda), or in an acid fixer bath, which contains potassium metabisulphite. It is then washed and dried, but hardening can take place without drying of the picture.

The fixed plate or film is then coated with a hardening solution of about the following Treated composition: 56.6 g ιoprozentige copper sulfate solution, 50 g ioprozentige Potassium bromide solution, 1.8 g of io percent potassium dichromate solution, 4.8 g of i percent Chromic acid solution, 115 g distilled water. This solution acts on the silver gelatin image and hardens the gelatin in relation to the image shade.

This composition can also be used to achieve special printing properties can be changed by the fact that the ratios of the chemicals used be chosen differently. Other substances can also be added or used as a substitute for the above, if they have a corresponding effect on the silver mass used in the photographic Image is included. For example, a higher addition of chromic acid produces an increased hardening of the colloid during a smaller amount of chromic acid produces a correspondingly lower hardening. Copper chloride and sodium chloride can be used in place of copper sulfate Find.

If, after the hardening process is complete and the Films finds that the colloid (gelatin) has not become hard enough to cause the Printing to withstand the forces generated on the plate or on the The colloid layer located on the film is further and finally hardened by the fact that it into a hardening solution, for example a weak solution of chrome alum or a other salt with a similar effect is brought.

The plate or film can now, if desired, dried and then the printing process can be carried out at any time.

In order to produce a silver colloid image hardened according to the invention for printing with grease ink, As with the collotype, to 'prepare,' the surface is covered with a solution of glycerin and water treated, followed by inking and printing in this printing process usual way can go on. Instead of glycerine and water, other known agents of a similar type can also be used will. Any of these solutions can also be used in conjunction with other chemical substances, which help the colloid either absorb or repel the fat color.

Inking and printing are carried out in the usual way for collotype printing.

The tone or shade values of the image can thereby be changed at will that the exposure and development of the photographic positives in the following Way is done:

A modification of the procedure just described consists in "that instead of the Wash the plate or film after the fixed image is hardened, thereby eliminating the Image is bleached, the bleached image itself in a solution of sub-sulfuric acid Soda (fixing soda) is brought to some of the silver or other components dissolve in order to bring the chemical action to a standstill, after which one washes out.

However, the best results have been achieved when the bleached, in the The colloidal layer of the plate or film retains deposited silver.

After the treatment described above, the plates or films can be inserted into any for example, a high-speed press with a level foundation is used and impressions are made of them here. The colloidal In this case, the layer can lie on a base plate made of glass, metal, celluloid or other suitable material, whereby possibly; a pliable or pliable layer on the foundation of the press is placed. Should the printing be done with a high-speed rotary press a flexible base layer must be used.

Long strips or endless tapes of film containing the prepared image can be can be colored, and prints can then be made on paper rolls or in the usual way Manner, which makes it practically possible to produce cinematographic images in printing inks on paper roll conveyors or other suitable materials. Even with this type of application, the customary commercially available cinematographic Positive films can be used.

In such cases, the images are reversed, but this is more of an advantage because with the means used for projecting such prints the images correctly Appear on the projection screen. The invention can also be used to manufacture of enlarged positives that can be used as printing surfaces. The invention can also be used where a collotype surface has been used, whereby the plate, the film or the like. A print of

a reversed photographic negative using the photomechanical one Processing is common practice. The negative can be under disapproval of a prism, if this is to be done by photographic means, or it can be the negative film of his The wing can be detached and turned in a known manner. If necessary, can also

ίο the positive through during the exposure any known means are used,

for example by the fact that the positive

Plate or film in a camera

- a negative is exposed, the back of which

turned towards the lens. These methods are known per se and are found in many photomechanical ones Procedure application.

Claims (6)

Patent claims: i. Method of making a for Collotype printing or light glue printing usable grainless printing surface from one in an invisible image contained in a silver colloid layer, characterized in that that the development of the exposed plate bearing the invisible image or of the film happens by means of a developer which, although in the usual way on all silver parts of the affected by light Colloid acts in relation to the exposure intensity, but its effect is so weak or delayed that it creates an extremely delicate, thin image that lacks any depth and density and that consists of very small amounts of reduced silver, which remains suspended in the colloid, whereupon the Colloid is chemically hardened in the presence of the silver. 2. The method according to claim 1, characterized in that the development of the exposed plate o. The like. That one or a series of invisible silver images in the Contains colloid layer, means of a strong So - OK Potassium bromide solution, i, S ! - 10 Potassium dichromate solution, 4.8 i - I Chromic acid solution, "5 - distilled Water. diluted developer, expediently an amidol solution, takes place, the twelve to is thinned twenty times compared to the usual method of use in the photographic process. 3. The method according to claim 1 or 2, characterized in that the chemical The colloid showing the delicate image is hardened using a solution containing the following ingredients: 56.6 g 10 percent copper sulfate solution, 4. The method according to claim 1 or subclaims, characterized in that that the development according to claim 1 and 2, the fixation and the chemical Hardening in relation to the image tint according to claim 3 in three separate sections is made. 5. The method according to claim 1 or subclaims, characterized in that that the colloid of the printing surface prior to its final setting for printing by means of Fat paint is finally hardened, for example by treating the image area by means of a weak chrome alum ·. like saline solution. 6. Grainless printing surface for use in light or light glue printing processes, characterized in that 'The silver of the picture is suspended in the colloid in such a finely divided state finds that it reproduces an extremely faint, delicate and thin image, the every depth and density is missing, whereby the tones and shades are graduated in the right proportion to each other and the colloid has been hardened in relation to these image tonal values.