US1609091A - Collotype printing form and process of producing the same - Google Patents

Description

Nov. 30', 1926. 1,609,091 1 A. .MILLER COLLOTYPE PRINTING FORM AND PROCESS OF PRODUCING THE SAME Filed August 14. 1924 Me mar/m1 uw parf Patented Nov, 30, 1926.

UNITED STATES PATENT OFFICE.

ALFRED MILLER, 01 DESSAU IN ANHALT, GERMANY, ASSIGNOR TO I.

- INDUSTRIE AKTIENGESELLSCHAFT, E FRANKFORT-ON-THE-MAIN, GERMANY GOLLOT YP E PRINTING FORM AND PROCESS OF PRODlZTEJING -'JIIBIE SAME.

Application filed August 14, 1924, Serial No. 732,119, and iii Germany nercu aa 1924.

' Phototypy has been performed in the following manner: I

A glass-plate prepared in a sultable manner receives an alqueoussolution of gelatme 5 and alkali-bichromate and is dried in an oven at a high temperature. In this man- .ner' there is formed a certain wrinkling of the gelatine over the whole plate; this 1s the so-called phototypic grain (compare A1- 10 bert, Lichtdruck, 1906', page 32). The dried plate is then exposed under anegative and afterwards thoroughly washed and dried,

whereupon it is moistened .as usual with water containing glycerineor the like and the printing operation may begin. This process has the disadvantage that the printer is obliged to prepare the materialhimself.

The said disadvantage is overcome-by other processes already proposed by Wl'llCll firstly on the support (plates or films) a hardened'gelatine layer is applied and dried.

Such plates can .be manufactured in large quantities and delivered" to the printers. They are sensitized directly before use in a 2'5 bichromate solution, dried at ordinary temperature or in. a yveakly warmed current of air. then exposed to light under a negative,

. washed in water at ordinary temperature,

dried and treated with glycerine containing water. Such a-printing form contrary to the old 'phototypic plate totally grain less, as well in the lights as in the shadows. Pictures produced from them when comparediwith the impr'css'ionsobtained by the old phototypic process have thedisadvantags that they show an essentially steeper gradation and the half-tones, particularly on large surfaces have a certain hard and cold appearance which is not to be observed in theold phototypic process.

Therefore, attempts were made, to give a.

grain to plates manufactured inthe just described manner and exposed to light under a negative by. acting with chemicals,

such as formaldehyde in connection with acids, on the gelatine layer. This process could not be readily introduced into practice. as the formation of a good grain de-.

from a colloid layer which may be spread .upon a suitablyprepared' support, such as duced. After a glass plate, a brass plate or a .film. The colloid layer if) desired may contain a fine G. FARBEN- I grained material such as barium sulfate which renders the colloid slightly opaque when wet and thereby'afl'ords a better sur veying of the inking, operation of the finished printing form. It should be understood, however, that this feature does in no wise affect the forming of the grain hereinafter described; The layer, is sensitized in the usual bichromate bath. If .as colloid unhardened gelatine' be takenthe layer is dried at a moderately raisedtemperature of about 30 0., whereby no grain is prothe layerhas been exposed under a negative it is washed in moderately dried. i If a more or less hardened -colloid, for example a hardened gelatine is employed,

with bichromate'solution is dried at a raised temperature. higher. than that employed for .unhardened ,gelatine, that is the temperature must be the higher the greater the degree of warm water, for instance at 2025 (3., and V thelayer-whichhas undergone thetreatment hardness of the colloid. The drying tem- T peratures are relatively low,however, and should not exceed approximately 35 C. Similarly the temperature of the washing water preferably is raised in proportion to the degree of hardness of the colloid.

4 There is thus formed in the exposed places in proportion to the degree of action of'the light Which produces insolubility of the gelatine a more or less pronounced grain. Thus in contradistinction to the old phototypic plates which have a grain over thewhole surface, th'e'plates produced by the new process are grained only in the exposed places, while those parts which have been completely protected from'light are without grain. Under a magnifying glass the grain" is seen to have extra-ordinary closeness and uniformity, whereas the ordinary phototypic grain frequently has clefts in it and is irregular. The printing forms prepared accordingtothe present invention are distinguished from those produced by any prior method by the fact that, due to the low drying'temperatures applied, the areas which have notbeenaflected by exposure to light, i. e., in the high lights and espec'ially the white margin surrounding thepicture area, are entirely without grain. By this lack of grain in the areas, which, in

the final print, shall appear entirely colorless, there is avoided the troublesome ml;- ing of those areas; which latter is expenenced in using. those printin forms which have an over-all grained sur ace.

The printing forms manufactured by the new process give excellent and just as well graded prints as the old phototypy and are devoid of the aforesaid disadvan tages of the other processes. Instead of hard and cold pictures the forms produce soft and warm pictures. The advantages of the. processes mentioned above are united in the new process.

For the sake of illustration reference is made to the accompanying drawings in whichr Fig. 1' is a sectional view showing asupport 1 carrying a colloid layer 2 before treatment according to the invention;

Fig. 2 is a similar sectional view showing a phototypic printing form prepared by treating the colloid layer 2 in accordance ing itin warm water. I

printing forms,'which consists in sensitizing by means of afchromieacid salt a colloid surface, drying the sensitized surface at a temperature of 28 C. to 35 C. depending upon the degree of hardness of the colloid, exposing it under a negative and then wash- 2. -A process according to claim 1, wherein the colloid is gelatine.

3. Aprocess according to claim 1, wherein the colloid surface has embedded in itfa finely grained material. 7

4. A process according to claim 1, wherein the colloid surface has embedded in it finely divided barium sulphate.

5. In a process ,of producing 'phototypic printing forms from a colloid, the steps .the degree of hardness of the colloid, ex-

posing the thus prepared surface and then washing" the exposed surface with water having a temperature -of about 20 C. to

7. In a process of producing phototypi'e printing forms from a colloid, the steps which consist in sensitizirig'th'ecolloid surface by means of a chromic acid salt, drying the sensitized surface at. a temperature not exceeding 35 0., exposing the thus prepared surface and then washing the exposed surface with warm water. j

'- 8. Process according to claim 7, wherein the colloid is gelatine. Q

9. Process accordin tQ' claim 7, wherein the colloidcis hardened gelatine.

10. A collotype phototypic pfinting form in which all areas defined by exposure to light .aregrained and all areas unaffected by the light are without grain.

11. A collotype phototypic printing form in which alljareas defined by exposure to light have a 'grain the quality of which is proportional to the'light effects defining the printing surface, and all areas unaffected by the light are without grain.

12. A collotype phototypic printing form in which-all areasdefinedby'exposure to light have a grain'proportional in distinctness to the degree of insolubility caused by the light effects, andall areasunafi'ected by the lightare without grain; In testimony whereof 'Iaflix my signature. I

- ALFRED MILLER.

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