US2137725A - Transfer device - Google Patents

Description

TRANSFER DEVICE Filed NOV. 27, 1954 1ra/ees myn? INVNTOR.

Mg, B MWL ATTORNEYS Patented Nov. 22, 1938 UNITED STATES PATENT ori-ICE can Proofing Company, -New York, N. Y.; a eorporation? of New York 'Application November 27, 1934, Serial No. 754,993

y.z claims.

LMy invention relates to a new and improved transfer device, to be used vfor the photomechanical reproduction ofy printing plates.

One ofthe objects ofmy inventionis to provide a device which can `be used in 'connection with the method of making printing plates which is disclosed in U. S. Patent No. 1,382,613 issued on June 28, 1921,-and ,in Canadian Patent No. 325,250l

issued, on August 23, 1932.

Another object of my invention is to provide an improved device for mechanically producing a photographictnegative from a photo-engraving.

2o. forth in the following description and drawing.

Fig. 1 is a diagrammatic cross section of improved device. Fig. 2 is a diagrammatic plan view. ft has heretofore been well known to make a printing plate from a relief plate'of the subject. rlihis relief plate may be made of metal, and it may be etched. Accordingfto this well-known method, as disclosed in the above mentioned 'United States patent and the Cabovementioned Canadian patent, the plate is first cleaned, and then a suitable opaque pigment is applied to the printing surface of the plate, so that the pigment Vfiller fills up the etched or relief portions of the plate, to a level with the printing surface of said plate.

' This plate, so prepared, is then pressed against the surface of a suitable base sheet made of Celluloid or other suitable cellulose material. According to said U. S. Patent No. 1,382,613 the surface of the base sheet of Celluloid is coated with an adhesive which is a solvent of Celluloid, just before' the transfer is made.

According to said Canadian patent, a sheet of g paper or tracing cloth of Celluloid or Cellophane or gelatin, is coated with a thin layer of rubber in solution, in order to form an adhesive film on the transparent or translucent sheet, just before the transfer is made, and the rubber solution is used the I for removing the pigment from the metal relief printing plate. e

According to my. invention, the metal relief plate, prepared, in the manner previously described, or in any other manner, is used for printing a'negative upon a sheet of cellulose acetate,

whichis coated with athin layer of substantially pure rubber.. 1 yReferring to the annexed diagrammatic drawing, the inner surface of the transparent or trans-f lucent sheet 3, which is made of cellulose acetate, is especially prepared in order to enable the rubber coating 2 to adhere thereto. Said inner surface 4 of the sheet 3 may be so prepared, so as to give -it a sufficiently rough surface, by means of embossing, or by any other process. Likewise, said inner surface of the sheet 3 couldbe roughened by coating the same with a mixture containing crystalline substances. Such a mixture could consist of gelatine having mineral crystals. The sheet 3 remains light-permeable and substantially transparent or translucent, after it has been provided with' a rough inner surface.

The roughenedsurface which is thus secured,4 is provided with a'coating or-layer 2. This coating or layer 2 consists substantially of pure rubber.- It may consist of parts of the whitest obtain-l able grade of first latex crepe, and 5 parts of white petrolatum. This rubber mixture: is milled to give it satisfactory calendering qualities and this mixture of rubber and petrolatum is then applied to the base i, by means of a calender. The thickness of the coating 2 can be from two thousandths of an inch to three thousandths of an inch.

It will be noted that I do not use av coating or layer which is a solvent for the cellulose acetate, and thatl use a tacky rubber layer which is` applied in iinal form to the base sheet 3. I do not Wish to be limited to the use of cellulose acetate, as I can use other suitable opaque or transparent or translucent material. I prefer to use cellulose acetate because l have discovered that it holds its dimensions more accurately than similar material, during the photographic printing operation. However I could use sheets of cellulose nitrate material or any other light permeable material. The coated sheet 3 is now covered with a third or 'covering sheet l, which is also preferably made of cellulose acetate. The covering sheet l is preferably provided with a smooth inner surface, and it is applied to the coating 2 of sheet 3, immediately as the coated sheet 3 comes from the calender.

The rubber is not vulcanized. The large-sheets of material'which are thus secured, are then cut to various sizes and packaged for shipment. I can use any suitable smooth or other material for the covering sheet I.

When the device is to be used, the covering sheet is removed and the tacky layer of rubber remains adherlngto the base sheet l, because said base material has a rough surface, and the covering material has a smooth surface. Hence the adhesion of the layer 2 to sheet 3, exceeds its adhesion to sheet i. T'his eifect or result can be secured in any suitable manner. Since the layer 2 is very thin and coherent, it remains adhering to the rough surface of the base sheet. This base sheet I, together with its tacky layer, is used in the same manner as thev base sheets which are disclosed in the patents previously mentioned. That is, when a metal relief plate which has been coated with a printing composition in its recesses is pressed against the rubber layer, a reproduction of the plate is formed upon the tacky layer 2.

'I'here can be considerable variation in the formula of the rubber layer, without making it unsuitable. 'I'he essential characteristics of the rubber layer are that it shall have a surface of sufiicient tackiness to pull .the particles of pigment from the metal relief plate, and that it shall be as colorless as possible, and as transparent as possible. Likewise, the tacky material should remain unchanged, during moderate periods of storage under average conditions.

The base sheet 3 and the protective sheet I, have a thickness of .0075 inch. This thickness can be varied without departing from the invention.

For convenience, the device may be designated as a transfer device, since a replica of the metal plate is transferred to the tacky layer, by means of pressure. Likewise, the tacky layer may be designated as a dry tacky layer, since the tackiness does not depend upon the addition or use of any solvent. The petrolatum may be omitted or it may be substituted by any other suitable material which can increase the calenderlng properties of the rubber. Likewise, I do not wish to exclude from the scope ofv the invention a tacky rubber layer, which has solvent intermixed therewith. If such a layer were used, the covering sheet would substantially prevent any evaporation of the solvent, and the transfer device, together with its covering sheet, could be packed in any suitable wrapper, whichx could prevent any 5 substantial evaporation of the solvent. However, and for the reasons previously described, I prefer to use a dry tacky layer.

I have described a preferred embodiment of my invention, but it is clear that numerous changes 10 and omissions could be made without departing from its spirit.

The thin sheet of cellulose acetate material, used for making the base sheet or the covering sheet, is bendable and resilient, so that each said 15 sheet has a predetermined normal shape.

I claim:

1. A transfer device for use in photo-mechanical printing, said device comprising a base sheet made of light-permeable material and having a smooth outer face, said base having a lightpermeable layer of tacky material at the inner face thereof, and a covering sheet which substantially covers said layer, of tacky material, said base sheet having a roughened surface directly adjacent said layer of tacky material, said layer having greater' adherence to the base sheet than to the covering sheet, so that said layer adheres to said base sheet When the covering sheet is removed.

2. A transparent transfer device comprising abase sheet made of transparent and resilient material, said base sheet having a roughened face, a layer of tacky material on said roug'hened face, said tacky material consisting substantially of unvulcanized transparent latex crepe, and a cover sheet applied to said layer of tacky material, said base sheet having sufficient adherence to said layer to retain the same, when the cover sheet'is removed.

40 ROBERT R. LEWIS.

Images