US2127824A - Printing member for intaglio or rotary photogravure printing - Google Patents

Description

Aug. 23, 193s.

A. A. LEUCHTER 2,127,824

PRINTING MEMBER FOR INTAG'LO OR ROTARY PHOTOGRAVURE PRINTING Filed April 1751928 [lll/IIIA. E;

lll/A /N l EN TOR A uga/sf A e (fc/#er f1 TTORNE Y Patented Aug. 23, 193s l t l 2,127,824

UNITED STATES VPATENT oFFlcE PRINTING MEMBER FOR INTAGLIO OR ROTARY PHOTOGRAVURE PRINTING August A. Leuchter, Augusta, Maine Application April 1'7, 1928, Serial No. 270,639 5 Claims. (Cl. 101 401) Intaglio or rotary photogravure printing is bring about such condition of a substantially mostly done from cylindrical surfaces, each of disconnected electrolytic deposit, the cylinder Such cylinders chiefly consisting of an iron core, body is purposely prepared in such a way, by mounted upon a steel shaft, and carrying on its either oxidizing its surface or otherwise laying 5 outer periphery a. layer ofcopper, which when on an interference film, that the growing-fast 5N ground and polished to perfection, is etched upon. of such an on-coming electrolytic deposit to the and serves then as the actual printing-surface cylinder body is positively prevented in the procof such cylinders. o ess of electro-deposition.

Usually such layers of copper are produced While such and other similar methods posby electrolytic deposition directly upon the iron sibly offer certain advantages by producing a l0 body or core of such cylinders, and are carried readily detachable shell-like deposit, and vdo fato a thickness suitable for receiving from twenty cilitate the stripping-off of the deposit whenever to thirty etching in succession. Under the genits removal is desired, certain distinct disadvan- -eral proceedingsof carrying out the successive tages are entailed by such methods, inasmuch as l5`etchings upon vsaid outer layers of copper, it is a printing surface, and especially an intaglio 15 customary to remove an etched-in-surface, bearone, shouldl have an absolute tight and solid ing images to be reproduced by what is known connection throughout with the underlying cylas gravure" or intaglio-printing, by the process inder-body, because in the process of printing of grinding and afterwards re-polishing the face from such a cylinder, commonly known as roto- 0f said layer of copper in order to receive the gTavure printing, considerable pressure is ex- 20 next etching. erted by the impression-roller against the etched Under this commonly general procedure .the surface of the printing cylinder in order to force diameter of such printing-cylinders is being the paper, passing between themmost thoroughconstantly reduced for such successive etchings,v ly down into the depressions .of the etchings,

and it is not possible therefore to retain any in order to receive the full value of tone-grada- 25 I ixed standard diameters of cylinders, except a tion by the varying density of ink carried in thc ground-olf outer section, which had carried a etched-in images of the printing surface.

previous etching, were re-built, and thus the cyl- Since best results can only be had in intaglio inder brought back to Vits former diameter by an or rotary photogravure printing by exerting conadditional deposit of copper. siderable pressure against the printing-cylinder, 30

Since it is highly desirable to maintain a fixed it is clearly obvious that a loosely laid-on shell, standard diameter for such printing cylinders, lWithOllt any intimate and Solid Connection With and to avoid the .process of grinding-oil' used the Vunderlying cylinder-bodl/Can not present printing surfaces, and gradually re-nishing the an ideal printing surface, kconsidering the press newly exposed copper surface to make it suitable OperatiOn 8.10116. but Other and greater Obje 35 Jfor receiving a 4IEW etching thereon, but at the tionable features are present ywhen the etching required expenditure of from eight to ten hours and preparation of the printing surface in genoi' timeand effort, different meanshave been eral is carried out. 4 suggested and devised to dispose of such used In such latter operation, in order to get best I 40 printing surfaces, and to replace them in much o effects, considerable retouching, tooling, re-en- 40 l shorter time by new deposits of the same thickgraving and the like are commonly practiced, ness, thereafter made ready to lreceive a new and must be resorted to, and such work is natetching. urally more safely and practically carried out on One of `such means, embodies a method Wherea solidly connected layer of copper than on a by a thin layer 0f Copper is deposited upon the loose shell, where there is always danger of cut- 45 cylinder body without becoming solidly attached ting-through in any operation of hand-tooling, t0 the Same. except at the two extreme ends of or the-loosening of such a shell in spots by burnthe cylinder, but otherwise forming a loose deishing, or by having any ink work its way untachable shell extending all over the periphery derneath through any possible pores in sucha of the cylinder, which feature enables the reshell-deposit, and eventually may causea loosen- 5 moval of such a shell by shaving or cutting ing or buckling of such deposit in the process of through the two extreme solidly connected ends printing. of the same, whereupon such shell can be readily It is for this reason that such method of removed from the cylinder body by peeling, after preparing and producing of printing surfaces by a lengthwise incision is made in the same. To means of a detachable shell has not met with u approval and is more or less objected to when and to produce by a different proceeding a printing surface of an electrolytically deposited layer of copper of suitable thickness to receive and carry an intaglio etching; but such layer of copper is so intimately and tightly deposited onto another layer of a hard metal, which forms the outer periphery of the cylinder body, that removal of the deposited layer of copper is not possible by any mechanical stripping method, but

- could only be accomplished by either grinding,

or turning-off in a lathe, or else by electrochemical dissolution in an electrolyte, or by other chemical disintegration in reconverting the metallic copper into a copper-salt or oxide.

While I have under my newly devised method of producing removable printing surfaces, either cylindrical or flat, a choice of three distinctly different ways to effect such removal, I prefer the one of electro-chemical dissolution as the most practical and economical one, whereby I am enabled to re-deposit the copper-layer from the cylinder surface back onto the anode plate, thus saving from eighty to eighty-five per cent. of the originally deposited copper, that is, of the layer first deposited to form the printing surface on the cylinder; and naturally such saving of copper repeatedly takes place every time a used printing-surface is removed to become replaced by a new deposit.

With such objects in view, my invention consists of novel features in the printing member, such as cylindrical or flat, and in certain process steps, to be hereinafter described and then claimed, with reference to, the accompanying drawing, illustrating the invention as preferably applied to a printing cylinder, and in which: Figure 1 is a longitudinal section before the .copper deposit is formed, and

Fig. 2 is a similar section after the deposit has been made.

In the drawing, a steel shaft 5 has the core 6 of the printing cylinder mounted and fixed therein in suitable well known manner. This is but one form of printing cylinder to which the invention may be applied.

To make the removal of a used printing surface possible by electro-chemical dissolution of the copper, and in this way convert it back onto theanode-plate, it is necessary to carry on the cylinder body 6, and to constitute the' base for the final layer-of copper forming the actual printing surface, a layer 1 of hard metal, capable of receiving and mechanically and intimately combining with the on-corning electrolytic deposit at the time such final layer 8 of copper is grown thereon by electro-deposition; and also on the other hand, when the removal of such body 8 of copper is undertaken by electrolytic action, said layer 1 of hard metal must also be capable of resisting corrosion and dissolution in the electrolyte under the influence of the reversed current, when this layer 1 of hard metal must then actually serve as an insoluble anode, and remain immune to any reaction of both the current as well as the copper-electrolyte usually employed. The electrolyte is the usual acid copper bath. The speed of rotation of the cylinder during electro-chemical treatment may approximate 200 revolutions per minute, for example.

Since a used intaglio printing surface naturally consists of an unevenly-thick layer 8 of copper, due to the fact that the same carries the etched-in images of varying depths, it follows that in the course of electrolytic dissolution the etched-in sections of such layer of copper become dissolved first, by reason of being thinner, thereby exposing the layer 'l of hard metal underneath in those sections, and which now must remain unaffected, while gradually the copper is being dissolved completely all over, the thicker sections taking the longest.

When all traces of the copper layer 8 have disappeared, and the layer l of hard metal is now completely exposed, it is only necessary to break the reversed current connection, under which the cylinder had been made the anodeterminal, and the anode-plate been the cathodeterminal in the electrolyte, and after brushing the cylinder with the hard metal layer, all bare on its outer surface, clean from any scum or foam of a gaseous formation, a new deposit may be formed again immediately, by throwing the reversible current switch back into its normal position, when thereby normal current connections become reestablished in the depositing-tank, and the cylinder is made again the cathode-terminal in the depositing solution, and copper-depositing proceeds again onto said layer of hard metal 'l until the desired thickness of copper layer 8 is reached, which latter is determined by the ampere-amount of current flowing in a given period of time.

As this layer of hard metal remains entirely unaffected by any reaction of either current or depositing solution, no change in size of cylinder body will take place, thereby assuring standardizing sizes of cylinders, which under the old method of grinding olf the used printing surfaces and thereafter re-nishing, to facilitate etching-on of new printing-images, was not possible, but causes constant reducing of cylinder sizes with every new etching effected thereon.

that the outstanding feature of this invention is an absolutely solid and perfectly united non-.

stripping layer of copper on the outer surface of a cylinder body, whereon all the usual operations of etching, retouching and tooling, as become necessary in the preparation of intaglio printing surfaces, may be carried out with utmost security and no danger of causing the said thin layer of copper to come loose or lift from the cylinder body; neither would any amount of pressure in the printing operation have any detrimental stretching effect on same, nor could even a local grinding operation effect a loosening of its hold on the underlying body.

In making an individual deposit for every etching, only a thin layer is necessary, requiring at best only polishing; and due to the fact that the removal of the used printing face can be accomplished by electrochemical dissolution, and thereby the layer of copper be transferred from the cylinder back onto the anode-plate, and as the same would be repeated with every renewal of the printing face of a cylinder, a great saving of copper is realized especially in the continuous run. For example, the thickness of the copper may be from three to six thousandths of an inch, and the hard base preferably thicker.

All such achievements are solely due and possible only by the creation of a layer 'I of hard and impervious metal completely encasing the iron core 6 of the cylinder body, or such other layers of softer metals the latter may consist of, and be directly underneath and adjacent to the final layer of copper, which has to serve as the actual printing surface of a cylinder.

'Ihe evident purpose of this layer 'l of hard impervious metal, preferably consisting of nickel,

or a combination thereof to increase the corrosive resistance, is to form a permanent base for the layer of copper constituting the actual printing surface, with which it must most intimately unite; but also on the other hand the base layer I must serve as a positive protection against corrosion and disintegration of the cylinder body, of which it is a. most vital part, when dissolution of the copper layer is enacted and carried out by the electro-chemical process for the purpose of removing a used printing surface.

In creating such a layer 1 of impervious hard metal the invention is not conned to the employment of nickel, but there could be used any other metal capable of resisting the corrosive action of the copper electrolyte combined with the influence of the reversed electric current, under which condition the cylinder-body actually becomes the anode-terminal, and must then assume all properties of an insoluble anode, as soon as any etched sections of the copper-layer have yielded to electro-chemical dissolution, and the layer of the impervious metal underneath becomes exposed, since it is only in such way that the disintegration of the cylinder-body below said final layer of copper is positively prevented, and thus a permanent unaffected base for said outer layer of copper is created.

Other metals of like corrosion resisting property that might be considered for such purpose would be chromium, platinum and also lead, but it is preferred not to use either of these for the reason of being highly expensive, as is the cost of platinum, or a perfect union with the final layer of copper is not possible, but might only be used when a detachable copper-shell Ais desired with a view of stripping or peeling-oli' bodily; and finally a layer of lead is at best only a very soft body and very difficult to maintain in perfect physical condition, especially when considering that one principal requirement of this invention is the creation of a hard impervious layer of metal, capable of being brought to a true and high finish and so maintained during the continuous practice of building-on and taking-off said layers of copper, serving as printing-surfaces of cylinders.-

Besides, layers of such other metals are diilcult to produce in the required thickness but answer at best for a light plating'only, which would prove useless for this purpose, because, while in such state they might temporarily resist the corrosive action of the copperelectrolyte, they could not resist the powerful influence of the electric current passing through the cylinder body `as an anode and outwardly therefrom towards the cathode surface, and due to which tendency there is caused a loosening and lifting-up of any such lightly plated film or pellicle of the respective metal, and then of course, the cylinder-body would no longer represent an insoluble anode, but be subject to attack and disintegration, thereby ruining the same, and making the whole operation of removing such an outer copper-film a complete failure.

This very same tendency prevails in creating this necessarily hard and impervious layer of 'metal by the use of nickel, or a combination thereof with traces-of chromium or platinum injected; there also it is obligatory to deposit a heavy enough layer of such metal; so thatthe pushing and pulling power of the electric current passing through the cylinder-body and on towards the cathode surface, in its very act of dislodging and dissolving said copper layer by electrolytic process, has no longerany such ruinous effect on the layer of nickel.

It is evident therefore that Whichever corrosion resistance metal is used for creating such an impervious metallic layer, the same must be carried to such thickness that the powerful iniiuence of the reverse flowing current can have no loosening or lifting influence on such a layer, and cannot disturb the same in the least.

'Iherefore it is preferred to create such impervious metallic la'yer of nickel, as that is reasonable in cost, and the electro-deposition of the same can be carried to any ,desired and almost unlimited thickness with ease, and furthermore nickel possesses great tensile strength besides hardness, and may be turned or ground true, and also brought to a high surface-finish, which it is apt to retain due to its hard and non-corrosive nature, and in general it is the ideal metal for this very purpose.

The encasing of the cylinder-body with nickel is even carried to vfar greaterthickness than it is necessary to resist any detrimental current action, for the reason that it affords and brings about greater rigidity of the cylinder-body, usually consisting of cast iron and copper, and thereby prevents any sinking of sections of the cylinder periphery, and in general helps to keep the cylinder in perfect shape and true condition.

What I claim as new, is:

1. A printing member having a permanent base of hard, impervious, non-corrosive metal, and a thin outer layer of a different kind of metal for providing a rotary photogravure printing surface and which throughout its entire area is intimately and solidly united with such base, and which layer is of a character suitable for etching such printing surface, the outer layer being sensitive to electrolytic dissolution of its metal and the metal of the base being neutral thereto.

2. A printing member, including a main body, a layer of hard, impervious, non-corrosive metal intimately united with the body, and forming a permanent base, and an exterior thin layer of softer metal for providing a rotary photogravure printing surface and which is intimately andl solidly united throughout with such base, and which'exterior layer is of a character suitable for etching such printing surface, the exterior layer being sensitive to electrolytic dissolution of its metal and the metal of the base being neutral thereto.

3. A printing member, including a main body, a layer of hard, impervious, non-corrosive metal intimately united with the body, and forming a permanent base, and an exterior thin layer of copper for providing a rotary photogravure printing surface and which throughout is intimately and solidly united with the base by electrodeposition, and which exterior layer is of a character suitable for etching such printing surface, the exterior layer being sensitive to electrolytic dissolution of its metal and the metal of the base being neutral thereto.

y 4. A printing cylinder, including a core, a shaft on which it is tted, a layer of hard, impervious,

non-corrosive metal extending all over the cylindrical surface and ends of the core, and an exterior layer of copper intimately united with the layer of hard and non-corrosive metal by electrodeposition throughout the whole surface area of the hard, non-corrosive layer, and the cylindrical surface of the copper layer being of a character suitable to provide a rotary photogravure printing surface.

5. A printing member having a main body with

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