US2322530A - Intaglio printing - Google Patents

Description

June 22, 1943. Q J, MacARTHUR INTAGLIO PRINTING Filed June 14, 1939 5 Sheets-Sheet l as Q INVENTOR mark; I fiar 411% BY a ATTORNEY June 22, 1943. J, MaCARTHUR 2,322,530

INTAGLIO PRINTING Filed June 14, 1959 s Sheets- Sheet 2 INVENTOR ATTORNEY June '22, 1943. c, MacARTHUR INTAGLIO PRINTING 3 Sheets-Sheet 5 Filed June 14, 1959 ATTORNEY ii 5- r lNV ENTOR flrar/as j/Ziarflf/Zur Patented June 22, 1943 UNITED STATES PATENT OFFICE 3 Claims.

This invention relates to improvements in intaglio printing machines for applying and drying coatings and printings on web materials in continuous operations.

The advantages to be gained by the use of attractively printed light-proof, moisture-proof,

and dust-proof packaging materials are in some measure restrained by the material cost and .printing cost of suitably tough and flexible materials which naturally possess all of the above desirable properties.

Therefore, this invention has for its object the provision of methods and a machine whereby web materials of relatively low cost or comparatively low tensile strength can be suitably treated and printed in continuous operations and produce an attractively printed, tough, flexible material, which is substantially impervious to light, moisture and surrounding atmosphere.

Another object of this invention is to provide in such a machine a fixed path for the web material while it is in motion or at rest and also while the printing and coating cylinders are rtating either in or out of contact therewith.

A further object is to provide in this machine a web path wherein the length of web receiving ink and coat drying application between coating and printing operations is considerably longer than the length of web not receiving drying application.

A further object is to include in a machine of this character several of the improved features embodied in my web-Jed printing press, and which are disclosed in my copending patent application Serial No. 180,285 to obtain certain advantages thereof in web control, printing register, and prevention of web wastage.

Also, the invention includes the broad concept of providing a gravure printing cylinder, preferably mechanically knurled ,in suchfashion that the cylinder is adapted for the high speed application of relatively thick and uniform coatings of continuous film forming materials upon continuous web materials; the knurled gravure cylinder adapted for coating, by a unique arrangement of printing and drying assemblies, may be included in a multi-color gravure printing press so that the web may be first coated, the coating dried, and then the coated web printed upon the coated side, or alternatively, the web may be first printed and then coated by the continuous film coating, and dried, in continuous operations, all of which will become clear from the description hereinafter set forth.

Heretofore, the application of film forming (Cl. I'll-401.1)

substances, such as cellulose acetate or like cellulosic derivatives or rubber derivatives, shellac, or the like, to paper or to metal foil, or like sheet material, has been accomplished by roller coating, by spraying, or by running the sheet material over a drum and by the. application of the film forming, substances in liquid form to the sheet material from a hopper, with or without extrusion and stretching operations, and then subsequent drying operations, all of which entailed solvent losses and expensive and complicated machinery: also, such methods were commonly open to the criticism that the films produced were not uniform, but varied in thickness due to the difllculty in making adjustments in continuous commercial runs.

Also, heretofore, it has been common practice to etch gravure printing cylinders with a multitude of tiny pits, so that such cylinders could be used to apply color tints to a continuous web traveling through gravure presses. However, no one has suggested or devised an apparatus which is suited for multi-color printing and application of relatively thick film coatings upon a continuous web in such fashion that the coating can be applied to the web and dried, and then overprinted with multi-color printing, or altematively, an apparatus which allowed the multicolor printing of a web in a gravure printing press and then the coating of the web at any desired printing uhit in the same press with a film coating of any desired character, such as a cellulosic derivative type, rubber derivative type, or resinous coatings.

Therefore, it is an object of my invention to provide a gravure printing cylinder preferably suitably mechanically knurled so that it is provided with suitable ink- (or coating material) traps or wells that substantial film coatings may be applied by such gravure printing cylinders to rapidly traveling webs of packaging material or printing stock or the like. While in my preferred form of invention the gravure cylinder will be mechanically knurled, and while by ordinary methods the mechanical knurling of an ordinary gravure cylinder apparently is the most feasible manner in which to provide the suitable ink (or coating material) traps or wells; nevertheless, it is within the purview of this invention to provide chemically etched gravure printing rollers suitable for the high speed application of substantially continuous coatings upon web materials.

It is a further object of my invention to provide an improved gravure printing press so arranged It is a further oblect of my invention'to sciene tifically apply definitely uniform coatings of film forming materials in volatile solvents by means of an intaglio printing cylinder in an improved gravure printing press. such printing ylinder preferably being mechanically knurled, but in any event. being provided with a new and improved ink (or coating material) well, the said well being adapted to trap and-retain substantial quantities ofink or coating material, despite the wiping action of an oscillating doctor blade to wipe away surplus quantities of ink or coating fluid. a

It is a further object-oi my invention to continuously gravure coat and print, or alternative ly, print and coat in a single press composed of a plurality of printing or, coating units, a rapidly traveling web of sheetmaterlal, whether the same be paper or the like-or metal-foil, and to arrange the web so that its printed or coated will not contact idler rollers or other to drying. It is still a further object of my.inven tion to provide a coating or printing cylinder which may be moved into and out of engagement with the web impressing member rotatable in a fixed apparatus prior axis by means of a simple cam or eccentric apparatus, and furthermore, such disengagement will automatically force a braking shoe upon the web, holding the .web inlocked position. andso that this feature in combination with a register relocator means will avoid the wastage oi' web material.

. asaasso Fig. 5 is an enlarged plan view of a modified type or mechanically knurled gravure cylinder,-

showing a difierent type of ink trap or well; and gig. 6 is a cross-section on the line H of Referring to the figures more in detail and particularly to Fig. 1, a gravure printing press identified as I. is for the purposes of illustration shown as comprised oi printing or coating couples it, it and it respectively, the said printing couples each including a gravure printing cylinder II and an impression cylinder 20.

The metal foil web. or paper web, as the case may be, indicated as 22, is indicated as being unwound from roller 24 and as indicated in Fig. l, the web is introduced from one side of the or fluid coating press, into the press over appropriate idler rollers indicated as 26 and then its direction is approximately reversed so that the web is traveling in an opposite directionfrom .the. direction of its unwind, and when traveling in such opposite direction. is introduced into the first printing or coating couple indicated as i2.

4 From printing couple l2-the web is guided past idler roller 28 upwardly past vacuum or exhaust ports 30, thence further inwardly towards the central ,portion of the press, in a horizontal direction, past a hot air blast which is fed through a pipe opening indicated as 32 and thence downwardly in a vertical direction on a long reach past a cold air blast port indicated as 34 and thence past cold water drumjl, whereupon the web is ready for entry into the second printing or coat- It is still a further object of my inventionto provide a-unique web travel-circuit, so that the printed or coated web may quickly dry and to so arrange the printing or coating units to the end that coating and printing operations may follow consecutively andicontinuously.

companying drawings of preferred embodiments of the inventiozf, in which modifications maybe made without departing from the scope of the appended claims. i-

In the drawings: Fig. 1 is a. semi-diagrammatic view ot a gravure printing press, including three printing. or cdat- I in couples, and particularly showing the path ing unit, the printing or coating which was applied by the first unit being'completed and fully dried. All units are in. the same horizontal plane.

It will be observed and readily understood tion oi the apparatusexhausts volatile solvents from the-ink or the coating materials, and then subjects them to a hot air blast, and then a cold air blast, and then pastthe cold water drum in succession. Prior to the contact with the cold water drum, there is no contact of the freshly printed or coated, side of the web to any guide rollers or ,the like, thus giving a maximum amount of time for the drying ofthe freshly printed marial or coating without contacting the freshly printed or coated side of the web to any 8131387 ratus: this by virtue'of the .unique web travel I tircuit. The web has a much longer distance to traveLwhile drying, than it has to travel from the last dryingmeans to the next printing unit.

'1: desired, each of the three units l2, l4 and It may be. utilized to apply successive continuous illnrcoatings, or the web may be first printed in two. colors by units it and I4 respectively and then unit It utilized to apply a film coating over the printed matter, or alternatively, the coating be-directly-applied to the web in'unit I! of web travel, and also showing the drying ap'. I

paratus; a

Fig. 2 'is a send-diagrammatic detail of the printing couple illustrated and identified ll in Fi 1; Fig. 3.is an enlarged plan view of a mechanically knurled gra'vure printing cylinder provided with new, and improved ink or coating fiuid traps orwells adapted ior'the rapid application of film material; v

Fig. 4 is a cross-section on'the lined-4 of. Fig. 3;

coatings to continuously traveling webs of sheet then printing units ll and II respectively utillzed in successive printing'operations upon the It will observed from the same diagrammatic view of a printing \mit shown in Fig. 2,

namely the view of printing couple-l2, that I make provision by an eccentric actuated block bearing identified as, 38 for the vertical and horiaontal adjustment of the gravure printingcylinder it As indicated, I provide for an intermediate 4 position of the eccentric, ll whereby the printing cylinder may be rotated out of contact with the web, and also an extremely lowered n indicated semi-diagrammatically in position upon printing couple I l, it is possible to restore register, the details of such register relocator means being fully set forth and described in my co-pending patent application, Serial No. 180,285, filed December 17, 1937, entitled Web-fed printing press.

As indicated in Fig. 2, I provide substantially a closed inking or coating applying mechanism indicated generally as 40, and an adiustable Oscillating doctor blade assembly 50. and a substantially closed circuit 52 for the traveling web while the same is passing the exhaust ports, and the hot air blast. The web circuit housing may be formed of insulating board or the like if desired, and suitable hot aiizbafiies 53, 55 and ill will ordinarily be provided.

Impression cylinder 20 will be mounted in a fixed position but will be axially adjustable vertically. Also, as indicated in Fig. 2, the printing cylinders will be power driven and the drive of each of. the individual printing cylinders will as usual be common so that the couples will 'be synchronized. These printing cylinders may be lowered and rotated out of printing position, but the web will be maintained in its same fixed path by means of the impression cylinders'and idlers, as described more in detail in my co-pending application Serial No, 180,285.

It will be understood that the inventive concepts, either in whole or in part, described and disclosed in this application may be adapted to or used in a modified form in conjunction with the particular printing press inventions described and disclosed in my above referred to co-pending patent application.

An important element of this present application is the provision of a specially designed, preferably mechanically knurled gravure prlnt ing cylincler, specially adapted for the uniform application of film forming materials upon a rapidly traveling web of paper, foil, or the like, and so adapted by virtue of a so-called crater or subsidiary well formation, which gives greater wall surface, which prevents the picking up of the coating fluid from the ink well: in other words, the well acts as a coating fluid trap, and otherwise the doctor blade would lift out the coating or inking fluid.

The two regular geometric form of ink or coating fluid Wells illustrated in Figs. 3 and 5 are particularly adapted for the practice of my invention and it will be understood that while two plan views shown, namely Figs. 3 and 5, that these are enlarged plans, and that in fact when the configurations as shown are applied on a circular printing cylinder, that the diagonal lines, shown in the figures will spiral around the cylinder.

Considering Figs. 3 and 4; the ink cells or coatcylinder has an extremely narrow wall, namely wall which is in contact with the web, (the subsidiary walls are not), thereby allowing the coating fluid when it is applied to the traveling web to easily overflow from square to square, and fill in the narrow line 56 which is uninked or uncoated, as will be well understood by those skilled in the art.

In the modified type of ink or coating fluid cell shown in Figs. 5 and 6, parallel inking grooves 60 are spiralled diagonally over the surface of the gravure printing cylinders, by a knurling operation and ribs or baffles 62, forming ink traps 66, i

are formed crosswise to" the grooves 60, namely perpendicularly to their side walls, thus giving an increased wall area to the inking grooves, and

- also providing traps for the coating fluids.

ing fluid cells are shown as of a generally square shape (this is a preferred form only and it might In each instance the patterns illustrated in Figs. 3 and 4, and also 5 and 8, are mechanically knurled upon an ordinary gravure printing cylinder, and while this is a definitely preferred and most practical procedure, those skilled in the art may devise alternate means of attaining similar patterns, as by etching.

While the proportions may manifestly be varied, I have found that in the coating fluid well pattern illustrated in Figs. 3 and 4 that the main well walls indicated as 50 are preferably in a ratio of 1 of wall top to 20 of fluid area and range in depths from -003 to .0015", according to thickness of solid coating desired; whereas etched ink cells for printing purposes normally have a 'ratio of 1 of wall top to 3 of fluid area, and range only to depths of about .003. I have been successful in employing 16 such coating fluid wells to the linear inch-diagonal measure-or 256 to the square inch; whereas the usual etchedink wells for printing purposes may approximate 150 wells to a linear inch or 22,500 to a square inch.

Since the surface tension of fluid lacquercoatings or the like is ordinarily greater than the interfacial tension between the metal well walls and the fluid in the case of the normal type of plain wells (without the lower well walls), the lower well walls of my invention serve two purposes, namely they increase the surface area of a given quantity or lacquer within the well and also act as traps to aid the master well walls to retain the fluid contents thereof during the scraping action of the oscillating doctor on. the rotating gravure cylinder.

For a practical working example of the type oi coating possible with the coating means above described, I have found that 9% of solids comprised of 75% cellulose acetate and 25% diethyl and dimethyl phthalate (the phthalates being 43% and 57% respectively) in a mixture of a solvent comprised of ethylene dichloride and 20% alcohol by weight serves well to give a continuous film surface, when dried, and that the same will operate well with the wells illustrated and described. Also, that lacquer coatings comprising substantially 20% of ethyl cellulose and 80% solvent mixture comprising 20% alcohol and 80% toluol may be utilized. Other resins such as shellac, etc, may obviously be used or rubber derivative film forming substances.

By controlling the depth of the knurling, the

thickness of the coating may be determined and definitely uniform coatings for thousands and thousands of yards of web material can be obtained. The well depths may vary, according to my experiments, from .003" to .0015" according to thicknesses desired, and these ranges probably could be considerably modified. Other variables of course include percentage of solids, type of solvents, etc.

I: desired. cellulosic or rubber derivative films could be coated and printed by this gravure cylinder method upon backing materials from which the nlms could be stripped when dried.

It will be understood that in my preferred embodiment I propose to coat rapidly traveling web material running at normal gravure printing speeds in printing couple II, by means of a gravure printing cylinder knurled in a pattern as described in conjunction with Figs. 3 and 4, that the solvent vapors of such coating will be exhausted and the coating dried, and .then the coated web will be printed in one or more colors by virtue of printing couples l4 and I6.

It will be understood that while the illustrated forms of the invention which I have described illustrate certain preferred embodiments of my invention, I do not wish to be limited to the precise details which are shown, since it is obvious that the same may be considerably varied without departing from the spirit of the invention as heretofore described and that therefore, reference should be had to the appended claims for a definition of the scope of my invention.

I claim:

1. In a gravure web cylinder adapted'forhighspeed coating operations. a gravure cylinder having its web contact surface formed of two sets assaceo each'of a plurality of relatively narrow raised lines extending diagonally of the printed surface, the lines of one set merging with the other set and in the same plane. the merging sets of relatively narrow raised lines thus forming rectangular coating solution wells, and a plurality of rectangular wall surfaces within each of said wells, one within the other and ot successively lesser area, said subsidiary wall surfaces being below the web contact line, the two sets of diagonallv extending and merging web contact lines being so proportioned to the wells provided thereby that a coating fluid held by the wells and applied to a traveling web will merge at the web contact lines for. coverage of the web.

2. A gravure web cylinder adapted for highspeed coating operations constructed in accordance with claim 1, in which the ratio of the diagonally extending contact line surfaces bounding each well and the area of the well is about one to twenty.

3. A gravureweb cylinder adapted for highspeed coating operations constructed in accordance with claim 1, in which the, ratio of the boundary line surfaces of each of the contiguous primary wells to the area of the well is about one to twenty and the depth of the well ranges between .002 to .0015 inch.

CHARLES J. MACARTHUR.

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