US1302919A - Process of producing printing-plates - Google Patents

Description

J. A. H. H'ATT.

PROCESS OF PRODUCING PRINTING PLATES.

APPLICATION FILED APR. 26. I916.

Patented May 6 1919.

vlxlm-v/ll/llllmllv/lllllaa 4 \\\\\\v 4 I I WITNESS. I VENTOR I l I a I JOSEPH ARTHUR HENRY HATT, or BROOKLYN, new YORK.

PROCESS OF PRODUCING PRINTING-PLATES.

Specification of Letters Patent.

Patented May 6, 1919.

Application filed April 26, 1916. Serial No. 93,653.

To all whom it may concern Be it known that I, Josnrrr ARTHUR HENRY HATT, a citizen of the United States, and a resident of Brooklyn, in the county of Kings and State of New York, have invented certain new and useful Improvements in Processes of Producing Printing-Plates, of which the followi is a specification.

The invention fel ates to transfer or multiplying processes for, making printing plates, and in certain of its aspects more especially to such processes for making planographic printing plates. V

Objects and advantages of the invention will be set-forth in part hereinafter, and in part will be obvious herefrom, the same being realized through the steps and processes set out in the appended claims.

The invention consists in the novel steps, process and improvements herein shown and described.

The accompanying drawings, referred to herein, and constituting a part hereof, illustrate diagrammatically one manner of practising the invention it being understood that the drawings are diagrammatic and greatly exaggerated for the sake of clearness, as certain of th things shown are very minute and practically microscopic.

Of the drawings:

Figure 1 is a diagram of a design bearing element, such as a lithographic stone, or zinc plate;

Fig. 2 shows in edge view, the transfer of the design by meansof offset;

Fig. 3 shows in edge the design trans ferred in a light resistant or opaqu medium to the sensitized surface of a plate;

Fig. 4 shows in edge the exposure of the plate of Fig. 3 to the light;

Fig. 5 shows in central section, corre sponding in position substantially to line A-B of Fig. 1, the developed plate, developed after beingexposed as shown in Fig. 4;

Fig. 6 shows the printing plate with the design thereon, and

Fig. 7 shows in diagram the optional step of enlarging.

In carrying out my process, any kind of original or copy may be employed, and the original plate or printing means 1 may be made therefrom in any of the usual ways. Said original printing means may be a lithographic stone, or a planographic zinc or aluminum plate, in either case with a suitable design 2 thereon, or it may be a line ongraving or a half-tone plate. Any of these may be used and may be produced from the Original copy in various well known ways, although a lithographic or planographic original printing means is usually preferable.

In the prior art it has been customary to multiply such designs upon a printing plate by taking a plurality of impressions from the original printing means, such as the stone or plate above mentioned, on transfer paper, and laying down the various transfer paper impressions in desired positions upon the printing plate, which plate is to be used upon the press in printing simultaneously a plurality of the original designs at each impression by the press. -As is well known, transfer paper has a soluble surface, consisting ofa very thin layer of glycerin and starch, upon which surface or layer the ink impression of the design is made by the original printing means, such as the stone or plate. The ink design so impressed on the .soluble surface is placed in contact with, and

becomes adherent upon, the surface of the final printing plate. The soluble layer is then moistened, thereby is dissolved, and leaves the design upon the printing plate ready to be etched or otherwise prepared for printing. The use of transfer paper is subj ect to many drawbacks, such as the unavoidable thickening and deterioration of the design, being largely dependent upon the manual skill and good judgment of the transferrer, and being inevitably subject to a further thickenin and deterioration in the steps requisite 1n preparing for printing a taining and increasing the advantages possessed by such printing.

The final printing plate 4, (which in explaining the preferred form of practising my invention will be considered as a metal planographic plate, such as the grained planographic and offset presses) is coated With a light-sensitive coating 5 upon the grained surface. The solution for such a coating may be made from glue or gelatin, with a slight proportion of albumin added thereto, and a light sensitive chromic acid salt, such as potassium di-chromate. This light-sensitive solution may be spread over the surface of the plate in any suitable manner, as by flowing the solution over the plate, or by whirling theplate, and then drying the solution to form the light-sensitive, de sign receiving coating upon the plate. The design of the original printin' is then placed or imprinted upon th means e light sensitive surface of the final printingplate as many times as is desired, t e final printing plate being usually filled with duplications of one or more original designs. The preferred form of so multiplying the designs upon the printing plate comprises inking and, when necessary, otherwise preparing the original printing means for making an impression. The impression is then made from the original printin means, preferably upon an offset surface, w ich may be such a surface as is employed in the rubber offset hand press. In Fig. 3 a hand roller 3 having an ofiset surface is shown, although in commercial practice well known forms of apparatus may be used for this purpose. The design 6 on the offset surface is placed or imprinted in the desired position upon the light sensitive surface of the printing plate. By stretching, or varying the tension of, the

offset surface in varyin degrees before and after imprinting the esign thereon from the original printing means, the size of the design on the printing plate may be made either larger or smaller than the original, as diagrammatically shown in Fig. 7. This operation is repeated until the requisite number of inked impressions of the original design of the original printing means has been made upon the light-sensitive surface of the final printing plate, that is, usually, until the printing plate is filled. It will be understood, however, that the same original need not be used throughout, but that various originals may be used, one or more times.

When the designs are thus impressed on the light-sensitive surface of the printing plate, in proper or desired positions, they are preferably rendered more completelyopaque to light in some suitable manner, as by applying or rubbing into the ink ofthe design bronze powder, or other suitable opaquing material. There is thereby secured, in effect, the negative and the light-sensitive surface 1n one and the same support, and there must, therefore, necessarily be perfect contact and registry.

The light sensitive surface of the plate is then exposed to the action of light 9 for a lung the surface of the plate with a of absorbent cotton to remove any a hering proper length of time. The light acts on the light-sensitive layer where not covered by design and renders such parts insoluble in cold water. Thereafter the ink and powder of the designs are washed off from the sensitive surface by a suitable solvent, such as benzin. The plate is then developed, which is done by subjecting the plate to the action of water, the water dissolving all of the colloidal surface which was protected by the ink and powder from the action of the light and therefore remained soluble in water.

- In order to facilitate the development of the plate, and to be able to view the progress of the development to the best advantage, it is preferable to stain the colloid with an anilin dye, such as a methyl violet. When the plate has been properly developed, it is dried. At this stage the surface of the late is covered with the indurated or oxi ized colloid over all the non-design parts, and the portions of the colloid 7 which were beneath the design during the exposure to light having been dissolved by the water durin the development, the grained surface 0 the printing plate is left bare in the design portion.

When the plate is in this condition, the surface there is flowed over with a very thin solution of light-sensitive asphaltum, which solution is preferably constituted by dissolving the asphaltum 1n approximatel equal parts of chloroform and benzol. he asphaltum adheres to the design portions of the plate, but in the non-design parts the asmersing the plate in, a Weak a kaline solution, which may be made from potassium h drate. The development is aided b 3111)- e get particles of the colloid. The non-design portions of the surface of the plate now are bare, while the design portion 8 is covered by the layer of light-sensitive asphaltum and ink.

The plate may then be finished for printing in the usual manner, as by applying a planographic etch and otherwise proceeding in a known manner.

Where it is desired to reverse the etch, that is to change it from black to white and vice versa, the surface of the plate is coated with a light-sensitive solution containing only the albumin and omitting the glue, as

the vehicle for the light-sensitive salt. The impressions from the original printing means may be placed upon the light-sensitive surface in the manner already described and the ink image rendered more opaque by the application of bronze powder as before. The plate is then exposed to the action of light, and after'such exposure the ink and powder of the design are removed from the surface of the plate by means of a suitable solvent, such as benzin. The entire surface of the late is then evenly coated with a thin film of ink, and is thereafter developed and etched in the usual manner known in the art.

By the present invention a great advantage is effected in that the impressions from the original printing means are placed upon the smooth light-sensitive layer, which is better adapted for receiving a clear and sharp impression than is the grained surface of the plate itself which receives the impression in the usual transfer process. The im-- pression upon the sensitive surface, if found defective or undesirable for any reason, may be easily and quickly washed away by the application of a solvent, such as benzin, without in the least interfering with the light-sensitive surface itself. A fresh design impression may be subsequently placed at the samespot with perfect results. By my invention also not only is the thickening and deterioration of the design, such as is incident to transfer paper avoided, but the design may be actually made sharper or lighter upon theprinting plate, or it may be maintained without thickening simply by controlling or varying the duration of the exposure to light. My invention likewise avoids the difficulty encountered in the use of negatives or like design carriers superposed or laid against the light sensitive surface of the plate, namely, the lack of perfect contact with resulting lack of sharpness of the design upon the plate, and also avoids the deterioration due to the light diifusing action of the glass plate or like design carrler.

From all the foregoing it will be understood that a process has been provided embodying and realizing the objects and ad vantages herein set forth, together withother objects and advantages; and also, that departures may be made from the precise manner of carrying out the invention herein described, within the scope of the accompanying claims, without departing from the principles of the invention, and Without sacrificing its chief advantages. 7

What ll claim as my invention and desire to secure by Letters Patent is 1. The process of roducing a multi-design printing plate W ich comprises applying a light sensitive layer to the surface of a final printing plate, imprinting on said light sensitized surface impressions from original printing means by means of an insoluble, resilient offset surface exposing the designimpressed, light-sensitive surface to the. action of light, and developing and preparing the plate for printing. 2. The process of producing a multi-design printing plate Which comprises applying a light sensitive layer to the surface of a final printing plate, changing the size of the design for the printing plate by varying the tension of an ofiset surface after it is imprinted by an original printing means and before imprinting on the sensitized surface, imprinting, on said light sensitized surface impressions from original printing means by means of the ofiset surface, exposing the design-impressed light-sensitive surface to the action of light, and developing and preparing the plate for printing. 3. The process of roducing a multi-design printing plate w iich comprises placing upon the grained surface of a planograph1c printing plate a smooth layer of light sensitive material, imprinting a design by means of an insoluble, resilient offset surface upon the surface of said light sensitive layer in a light arresting medium, exposing the design imprinted, light sensitive surface to the action of light, removing the design constituting material from the light sensitive surface, dissolving the portions of the light sensitlve material which were beneath the design during the exposure of the light sensitive surface to the light, placing a design constituting material upon the exposed design portion of the grained surface of the printing plate, and removing the portions of the light sensitive layer remaining on the non-design portions of the surface of the printing plate.

t. The process of producing a multi-de- 1 sign printing plate which comprises placing 'upon the grained surface of a planographic printing plate a smooth layer of light sensitive' material, imprinting a design by means I of an insoluble, resilient ofi'set surface upon the surface of said light sensitive layer in a light arresting medium, exposing the design imprinted, light sensitive surface to the action of light, dissolving the portions of the 7 upon the grained surface of a planographic printing plate a smooth layer of light sensi t1ve material, imprinting a design by means of an insoluble, resilient ofiset surface upon the surface of said light sensitive layer in a light arresting medium, exposing the designimprinted, light-sensitive surface to the action of light, dissolving the design and the parts of the sensitive layer therebeneatlr which were not acted upon by the light, applying a design material to the so exposed portions of the ained surface of the printing plate, and dissolving the portions of the light sensitive layer remaining on the nondpsign portion of the surface of the printing p ate.

6. The process of producing a multi-design printing plate which comprises placing upon the grained surface of a planographic printing plate a smooth layer of light sensitive material, imprinting a design by means of an insoluble, resilient offset surface upon the surface of said light sensitive layer in a light arresting medium, exposing the designimprinted, light-sensitivesurface to the action of light, applying to the surface of the plate a medium which Will dissolve the design but which will not dissolve the sensitive layer, applying to the sensitive layer a medium which will dissolve only the portions of such layer which have not been acted upon by light, applying a design constituting material to the portlons of the grained surface of the plate thereby exposed, and applying a solvent to the'light sensitive layer remainin upon the non-design portions of the plate.

The, process of producing a multi-design printing plate which comprises applying a smooth light sensitive layer to the grained surface of a printing plate, imprinting a plurality of designs by means of an insoluble,resilient ofl'set surface in desired positions upon said smooth light sensitive layer from original printing means by means of an offset surface, exposing the sensitized and design imprinted surface to the action of light, dissolving the imprinted designs from the exposed surface, dissolving the portions of the light sensitive layer which were protected from the light action by the design, applying a design material to the portions of the printing plate so exposed, and dissolving the remainder of the light sensitive layer from the non-design portion of the plate.

In testimony whereof, I have signed my name to this specification, in the presence of two subscribing Witnesses.

JOSEPH ARTHUR HENRY HATT.

Witnesses:

JOHN D. MORGAN, LOUISA LOEHR.

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