US1804920A - Method of producing printing plates - Google Patents

Description

Patented May 12, 1931 PATENT OFFICE J'UNIUS D. EDWARDS, OF OAKMONT, PENNSYLVANIA METHOD OF PRODUCING PRINTING PLANS Application filed July 81, 1929. Serial No. 882,596.

My invention pertains to a method of producing printing plates. The invention is particularly apphcable to the production of printing plates such as have heretofore been produced by applying cut-out portions of rubber, linoleum, or like material to a suitable base, or by removing such materials from a base covered therewith, so as to leave the design to be impressed standing in relief.

Printing plates havin the impression 1parts thereof formed of ru ber, linoleum and indred substances are in common use. They are considered advantageous, for instance, where relatively large tint areas are to be printed, one reason being that the resilience of these materials reduces the amount of make ready which is necessary and enables an even tint readily to be printed. Another, and a growingly important, use of such print- 2 ing plates is in connection with the process of printing by means of the so-called water color inks, which process is ordinarily carried on along the lines of Patent No. 1,595,756 granted to Jeane Bert Inc., and is enerally known as the Jean Bert process.

rinting plates lll having metallic surfaces are found not to accept these water-color inks with readiness, and plates having the impression portions formed ofrubber, linoleum, or the like, are commonly employed.

' In producing such a plate for the Jean Bert process, for instance, the operator is su plied with a key proof from which he ta es an impression u on the rubber surface of a composite plate ormed by cementing a rubber sheet upon a metallic base. With the impression as a guide, he then cuts away, with a knife or other suitable tool, all of the face of the rubber except those portions from which 40 the impression isto be taken. He often has to cut up the composite plate, since different parts thereof will frequently be used for different colors. The result, for any one color ofa color printing job, is usually a plurality of metallic plates each carrying, in relief rubber, a portion of the design to be printed.- These platesare generally assembled on patent bases and are adjusted in position on the latter until they occupy precisely the correct location for the design, to register, for instance, with another color. Evidently, the time, labor and skill necessary to produce such plates and set them up correctly in the form is very great, and adds considerably to the cost of carrying on work of this character. I a

It is the prime object of my invention to provide a mode of producing printing plates, which obtains the desired results in connection with resilience and receptiveness to the co so-called water-color inks, and avoids the long and tedious steps heretofore necessary in producing and setting up plates employed for kindred uses.

According to my invention I coat a base with rubber, or a rubber compound or derivative, or other organic substance, ordinarily of a colloidal nature, capable of being applied by electro-deposition; and I a ply this coating in such a manner that the eslgn to be impressed stands in relief. One method by which this may be effected is as? follows: An ordinary zinc etching is made, having, of course, in relief, the design which is to be impressed. The low parts of such etchin are then coated with insulatin material suc as an insulating varnish. Th1s may conveniently be done b coatin the whole plate with varnish an therea 'er polishing the varnish away from the relief portions of the plate. 'Suc relief portions being duly cleaned, the plate is introduced, in contact, in this instance, with the anode, or constituting such anode, into a rubber emulsion in an electro-depositing bath of the general character disclosed in United States Patent'No. 1,47 6,37 4 dealing with the electro-deposition of rubber coatings. Such bath may, if de-- sired, be made to contain the requisite elements for subsequent vulcanization of the 99 rubberby the mere application of heat. The

coatingl of rubber will be deposited onl upon t ose parts .of the zinc etching whic are unprotected by the insulating varnish,- thatis to say, the relief parts correspondin to the design which is to be impressed, wit% the result that a plate is produced in which rubber portions correspondin to the design to be impressed stand in reli After the plate has been thus produced it 9 is removed from the depositing bath and washed, whereafter it ma be tou hened by vulcanization. If the emu sion in t e deposipositing bath has contained a vulcanizing agent, such vulcanization can be effected by the application of heat. Otherwise, suitable gaseous vulcanizing agents are employed in a well known manner. If found necessary, a suitable reliminary coating maybe applied, in accordance with well understood principles in the art of rubber deposition, to insure a firm adherence of the subsequently deposited rubber to the metallic base.

A printing plate according to my invention can thus be produced. with relative ease, and, moreover, containing the whole of any desired design, can be set up in the form, to register, for instance, with other colors of the job, quite easily.

I contemplate that it will not be necessary, in many instances, to apply the insulating coating to the zinc or other etched plate, though the employment of such coating tends towards good definition, and such coating can be removed, after deposition has taken place, if desired. The relief of the rubber coating will follow the relief of the original etched plate to a suflicient extent to fulfill the printing requirements in many cases. I further contemplate that it may not be necessary to employ an etched plate as a base, since a fiat base may be given (for instance, through a photographic process) an insulating coating over those parts thereof from which an impression is not to be taken,i. e. those parts which would correspond with the etched portion of an etched plate. Thereupon, the rubber can be deposited upon the parts of the plate not thus coated, thereby creating the design to be impressed coated in relief on the base. i

The accompanying drawings are illustrative of my invention, Figures 1, 2 and 3 representing vertical cross-sectional Views and Figure 4 a sectional perspective View of a printing plate, briefed with suitable legends to indicate the nature of materials and the operations employed in carrying out my invention.

I contemplate the use of other materials than rubber for the coating, such as compounds and derivatives of rubber, resins, and other organic materials which are capable of electro-deposition and have the desired characteristics of resilience or receptiveness to water-color inks, which materials are ordinarily of a colloidal nature. Where the term rubber is employed in the appended claims such materials are intended to be included.

I claim:

1. The method of producing printing plates having impression faces of rubber which consists in preparing a base having that portion of the surface thereof representing the design to be printed of electrical conducting material, and other portions of such surface of insulating material, and coating the first named portion with rubber by electro-deposition.

2. The method of producing printing plates having impression faces of rubber which consists in appl ing an insulating coating to one portion 0 an electrical conductingbase so as to leave uncoated another portion representing the design to be printed, and forming on the uncoated portion of such base a layer of rubber by electro-deposition.

3. The method of producing printing plates having impression faces 0 rubber which consists in applying an insulating coating to the recessed portions of a metallic base carrying in relief the design to be printed, and subjecting said base to the action of an electro-deposition bath containing rubber or the like, thereby to form a layer of rubber on the relief portions of said base.

In testimony whereof, I sign my name.

JUNIUS D. EDWARDS.

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