US2085048A - Method of making printing forms - Google Patents

Description

June 29, 1937.

METHOD OF MAKING PRINTING FORMS Filed Feb 27, 1931 2 Sheets-Sheet l L mm, I, lllmlm; "In mm M mq INVENTOR ATTORNEY o. R. SCHULTZ v 2,085,048.

June 29, 1937. Q sc u -rz 2,085,048

METHOD OF MAKING PRINTING FORMS Ffile'd Feb. 27, 1951 2 Sheets-Sheet 2 INVENTOR x114 ATTORNEY Patented June 29, 1937 UNTED srATEs PATENT OFFICE Cellu-Type Plate Inc., Union City, N. .l'.,

a corporation of New York Application February 2'7, 1931, Serial No. 518,649

18 Claims.

This invention relates to printing forms and more particularly to a printing form adapted to be applied to a printing cylinder or similar device, and to a method of constructing the printing 5 form. V

' A molded or engraved printing form of cellulosiccomposition attached to a printing cylinder constructed in accordance with this invention has been found to produce excellent and high quality printing work for one color or one tone printing half tone (letter press) and intaglio printing (rotogravuring). Where the printing form is to be used for multicolor printing it is desirable to mount the same on a non-stretchable backing so that any tendency of the printing form to stretch during use will be prevented.

Furthermore, where the printing work is heavy, as in the printing of designs on fabrics, composition materials and metal, printing plates of unusual strength are required. For such duty, whether multicolor or monotone, the ordinary printing plates heretofore used are not sufficiently rigid and strong to insure good work.

An object of my invention is to produce a printing form which will not stretch, shrink, or otherwise become distorted under the most severe operating conditions.

Another object of my invention is to provide a printing form especially adapted for multi- 9 color printing and gravuring work.

Another object of my invention is to produce a printing form especially adapted for muti-color printing, which, when aseries of my printing forms are secured upon the respective color cyl- 35 inders of the printing press, exact and precise registry of the color parts on the printed work will result.

Another object of my invention is to provide a printing form especially adapted for color work 40 which will not stretch, shrink, or become distorted under the most severe operating conditions, which is strong and durable in construction, and which can be quickly and easily made of inexpensive materials by ordinary'labor.

Still another object of my invention is to devise v a method of making printing forms for multi color work quickly and'easily, with inexpensive equipment, with few manual operations, and with the use of unskilled labor.

Other objects of this invention will become apparent as the disclosure proceeds.

In accordance with my invention; I provide a backing plate, which has a low co-efilcient of expansion and which will not stretch under severe 5 pressure strains. A thin sheet of cellulosic matemanner now used in the rial having a smooth and glass-like top surface is secured to the roughened side of the backing plate. The embossing is then placed upon the glass-like surface of the cellulosic material in the art. In making my printing form the backing plate is laid flat upon a table top whose surface is absolutely level. A cellulose solution of easily flowing viscosity is poured on the roughened backing plate at approximately the center thereof, allowed to flow freely over the entire surface of the backing plate and thus to assume its own level. Drip pans are provided to catch the overflow. The cellulose solution is then permitted to set, harden and freeze to the backing plate. The cellulose material when hardened will present a top surface which is glass-like in appearance, and absolutely smooth and uniform.

The smooth cellulosic surface of the plate thus constructed is placed over the copy relief, and a viscous cellulose composition or dope material is disposed between the plate and the copy relief. The plate is then rolled or pressed into contact with the copy relief, and the molded impression is cast in and formed by the dope material. Satisfactory results have also been obtained by placing the backing plate directly over the copy relief, placing dope" material between the backing plate and the copy relief and then rolling or pressing the backing plate into contact with the copy relief. It is understood that in such case backing plates should be selected to which the viscous plastic mass, which takes the printing impressions, has an afflnity. For example, as above noted a viscous cellulose composition will adhere to a cellulose backing sheet and the viscous composition can be pressed between the cellulose backing sheetand the copy relief. The dope material is then allowed to set, harden and freeze to the roughened surface of the backing plate. The layer of dope material when hardened must be of sufficient thickness to take the full embossed impression, and in addition fully and homogeneously cover the backing plate. It is understood that where viscous cellulose composition is used a cellulose backing sheet is first provided or formed and the cellulose sheet may either be attached to a more rigid backing, such as metallic or fibrous material, before the molding operation, or after the molding operation, as desired.

In order that a clearer understanding of my invention may be had, attention is hereby directed to the accompanying drawings, forming a possible embodiments of my invention.

Referring to the drawings, Figure 1 is a top face view of my backing plate showing the top surface thereof granulated or roughened;

Figure 2 is a diagrammatic illustration of one method which may be used in pressing the backing plate into contact with the copy relief so that the dope material disposed therebetween will take the embossed impression;

Figure 3 is an enlarged diagrammatic view of my completed printing form carrying the embossed impression;

Figure 4 illustrates one method of making a printing form of modified construction, the view, showing more particularly a casting table with the backing plate lying fiat thereon, and with cellulosic material in'solution flowing over the backing plate;

Figure 5 is a top face view of my modified backing plate as removed from the casting table, showing in particular the glassy surface of the cellulosic material after becoming frozen to the roughened backing;

Figure 6 is a side view of my modified backing plate showing more clearly the cellulosic material superimposed upon and'frozen to the roughened backing;

Figure? illustrates one method of pressing my modified backing plate into contact with the copy relief so that the dope material disposed therebetween will take the embossed impression;

Figure 8 shows my modified printing form as completely constructed;

Figure 9 is an enlarged microscopic detail of the printing form shown in Figure 3, taken along line 9-9 of the figure, this view illustrating the approximate comparative thickness of the various parts making up the printing plate; and

Figure 10 is an enlarged microscopic detail of my modified printing form taken along line Ill- H] of Figure 8, this View 'llustratin'g the approximate comparative thickn ess of the various parts making up this printing plate.

Similar reference characters refer, to similar parts-throughout the several views of the drawings.

In carrying out my invention I provide a backing plate preferably composed of metallic or other material which will withstand considerable pressure without stretching or distortion, which is preferably, and which has a low co-efiicient of expansion for ordinary room temperatures. I have found that copper is a very satisfactory metal to use for this purpose, although I do not limit myself to this material alone, but I contemplate using other well-known materials which possess the above characteristics, such as zinc, aluminum, ferrous and other metals, fiber, paper, or composition materials, within the scope of this invention. The thickness of the backing sheet used will depend largely upon the strength of the material and the ease with which it can be bent to conformto the surface of the printing cylinder. Where a copper plate is used a thickness of .015 to 0.1 of an inch has proven satisfactory, The backing sheet should be of uniform thickness throughout and somewhat larger than the picture which it is to carry.

The top surface of the backing plate In may be granulated or roughened, as shown more particularly in Figure 1.- The purpose of roughening the backing plate is to obtain a strong bond between the backing plate and the cellulosic printing surface. Roughening of the backing surface, how- 2,085,048 part of this app ication and illustrating certain ever, is an expedient to obtain a strong bond, and where certain backing materials are used, such roughening of the surface thereof may be unnecessary. The roughened backing plate is positioned over the copy relief II, as shown in Figure 2. Any form of copy relief may be used. For purposes of illustration, however, I have shown a copy relief having a gelatine surface l2 thereon suitably hardened and swollen with water in the well-known manner. The relief surface is produced in the well known manner which comprises photographing the object to be reproduced, exposing the sensitized gelatin surface through theiphotographic plate carrying the object image, screening the object image im-- pressed upon the sensitized gelatin by either intaglio or half tone screens and finally immersing the screened, image impressed gelatin surface in a water bath. A water swollen gelatin copy relief is thus produced carrying toned impressions of delicate shading which may or may not be screened depending upon the object to be produced. A dope material I3 is placed over the copy relief and between the copy relief and the backing plate H]. The dope material may comprise nitrocellulose, cellulose acetate, collodion, or cellulose esters of other acids, dissolved in a suitable solvent. The solvents used may be one or more of the many well-known solvents in commercial use, or a mixture of two or more of t em, such as ethyl acetate, butyl acetate, butyl alcohol acetone, alcohol, amyl acetate, and similar commercial solvents. Various lacquers in commercial use, shellac plastics dissolved in alcohol or like solvent, cold plasticizable phenolic resins and similar materials having characteristics of the cellulosic materials mentioned above,-may also be used. All of these materials, initially moldable and adapted to take an embossed impression and maintain the same upon solidification, are to be considered as encompassed by the terms dope material, cellulosic material and cellulose solution as hereinafter used.

As shown in Figure 2, a heavy roller I 4 is moved over the backing plate to press the dope material into the photographically toned fine grooves of the copy surface [2. The dope material I3 is then allowed to harden and set and soon becomes cemented or frozen to the roughened surface of the backing plate and takes an embossed photographically toned impression 'of the copy relief. When the dope material has become thoroughly hardened, which generally requires from fifteen to fifty minutes, the backing plate, with the cellulosic material l3 carrying the embossing frozen thereto, can be lifted or torn from the copy relief. I then have the complete printing form as shown in Figure 3 toned by the shaded photographic impressions carried by the hardened gelatine copy relief. If the backing plate is made of such material as the plasticizable mass which takes the printing impressions, the mass will firmly adhere and become bonded to the backing plate. For example, a viscous cellulosic mass will firmly adhere to a cellulose ester sheet and, if desired, a preformed cellulose ester sheet may be used as the backing plate. After the molded plastic masshas become hardened and frozen to the cellulose sheet, the copy relief may be separated therefrom and the cellulose backing sheet may be secured by means of a suitable adhesive to an additional backing sheet formed of metal or fibrous material.

' In making this type of printing form the dope material l3 must possess considerable body so that when fully set and hardened it will be of sufficient thickness to take the full impression from the copy relief, and in addition to completely cover the backing plate l so that no spots on the backing plate are left uncovered. When a dope of medium viscosity is used in connection with ordinary paper printing, a microscopic cross sectional view appears to show that the embossed-impressions do not generally extend into the dope layer l3 more than to the thickness thereof, as shown in Figure 9.

Ihave shown in Figure 4 a casting table which can be adjusted so as to present a table surface which is absolutely level. This table is used in casting a modified form of printing plate, which will now be described. The backing plate Illa of suitable material, and similar to backing plate Ill heretofore described, is placed flatly upon the table surface. The table is preferably provided with a glass top 20, having an absolute smooth and even top surface. The glass table top 20 may be supported by a tripod 2!, having three supporting legs 22. Three rectifying or adjustment screws 23 are provided by means of which the table surface can be leveled in the well-known manner. Spirit levels 24 are attached to the sides of the table top 20. By observing the spirit levels 24 and manipulating the adjustment screws 23,

the table surface can be placed in an absolutehorizontal plane. v

The backing plate Illa should possess no buckles or indentations and should be smooth and even so as to lie absolutely fiat on the table top 20 with the granulated or roughened surface thereof facing upward. A cellulosic material 25 dissolved in a suitable solvent and having substantially the ingredients contained in dope material 13 above described is then poured from a suitable container 26 upon the approximate center of the backing plate as it lies upon the leveled table. The cellulosic material should flow easily and to obtain this result an excess of solvent may be added. The cellulosic material 25,

I sufliciently liquid, will flow evenly over the roughened surface of the backing plate and assume its own level. Sufficient material should be poured on the backing plate to cause it to flow over all the edges of the plate. Suitable troughs 21 are provided to catch the overflow, the troughs 21 being so constructed as to conduct the cellulosic material by gravity into a receiving pipe 28 from which it can be caught in a suitable receptacle.

After the backing plate Illa has been completely covered with the cellulosic material 25, the pouring is stopped and the cellulosic material is allowed to set and harden in a clean, dry, and dustless room, freezing to the backing plate and forming a hard cellulose sheet. The cellulose sheet thus formed on the backing plate Illa may be from .005 to .015 of an inch thick, which is amply sufficient since the backing plate takes the strain when the printing form is attached to the rotating printing cylinder. If at any time it should prove to be desirable to make the cellulose sheet of greater thickness, it would be only necessary to place a frame wall around the backing plate as it lies on the casting table and thus contain the dope material upon the casting table and prevent it from running off. The dope material would, of course, assume its own level as before and the proper amount of liquid material to pour upon the backing plate to produce the required sheet thickness could be accurately gauged, either by measuring the amount of dope material poured upon the backing plate or by measuring the depth of the dope material spread over the backing plate.

I have shown in Figures 5 and 6 the product as removed from the casting table shown in Figure 4. The cellulosic material 25 hardens into a glass-like sheet and becomes frozen to the roughened surface of the backing plate Illa. Any unevenness or irregularity in the thickness of the backing plate Illa is compensated for by the cellulose sheet 25 when cast upon the backing plate by the method illustrated in Figure 4. A printing form of uniformthickness, when properly placed upon and secured to the printing cylinder, will present a printing surface which is absolutely round.

I have illustrated in Figure 7 one method of molding the printing plate from the copy relief II. The method of molding, shown in Figure '7,

is not essentially different fromthat shown and described in connection with Figure 2. The printing plate, with the cellulose sheet 25 facing downward, is rolled or otherwise pressed into contact with the photographically toned gelatine surface l2 of the copy relief I l. Dope material I3a. is rolled between the gelatine surface of the copy relief II and the cellulose side of the printing plate as before. The material l3a may comprise a plastic mass having a composition similar to the dope? material I3 above described. When the molding material I3a has become sufficiently set and frozen to the backing plate, the whole is lifted from the copy relief II. I then have my modified printing form as completed and shown in Figure 8. It is understood that my invention is equally applicable to the making of any and all forms of cast printing and reproduction plates and is not limited alone to intaglio and half tone printing forms, printing plates having the most delicate tones and color shadings can thus be produced.

The backing plate of my printing forms as made above takes the strain off from the mechanically molded, photographically toned surface when the form is attached to the rapidly rotating printing cylinder, and possesses sufficient strength to carry the printing pressure without stretching, shrinkage or distortion. The dope material carrying the molded surface does not assume any of the strains incident to printing. When my printing form as above constructed is properly-applied to the printing cylinder no stretching whatever of the printing form occurs, and all areas of the printing form remain in exactly the same position as first placed throughout the most tedious printing operation. Exact registry between the colored parts of the printed work is thus assured. Furthermore. mv

printing form as above constructed is strong and durable, adapted for the heaviest printing work, and can be quickly and easily made from inexpensive materials, with inexpensive equipment and with the use of unskilled labor.

' As many changes could be made in the construction and method above outlined and as many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

What I claim is:-

1. The method of preparing printing forms from aphotographicallytonedwater swollen copy relief which comprises, placing a viscous plastic mass' material in solution of cellulosic material upon the copy relief, applying a backing plate of, non-stretchable material over the plastic mass, and rolling said plate against said copy relief to spread said plastic mass therebetween.

2. The method of preparing printing forms from a copy relief which includes, placing a backing plate in a horizontal plane, coating said backing plate with a binding material, placing a plastic mass of cellulosic material upon the copy relief, cold pressing said backing plate with the binding material attached thereto against said copy relief, allowing the plastic material to harden and unite itself to said binding material, and removing the thus molded platefrom the copy relief.

3. The method of preparing printing forms from a copy relief which includes, placing a backing plate of non-stretchable material in a horizontal plane, coating said backing plate with a binding material, placing a plasticizable mass upon the copy relief, cold pressing said backing plate with the binding material attached thereto against said copy relief to spread the plastic mass therebetween, allowing the plastic mass to harden and unite itself to said binding material, and

removing the thus molded plate from the copy from a copy relief which includes, roughening' one side of a backing plate, placing said backing plate in a horizontal plane, flowing cellulosic material in solution over said backing plate, and

allowing said cellulosic material to set, harden and freeze to the roughened side of the backing plate, placing a plastic mass upon the copy relief, and cold pressing said backing plate with the cellulosic material attached thereto against said copy relief to spread the plastic mass therebetween.

5. The method of preparing printing forms from a, copy relief which includes, roughening one side of a backing plate, placing a plastic mass of cellulosic material upon the copy relief, and rolling the roughened side of said plate against the copy relief to spread the plastic mass between said plate and copy relief.

6. The method of preparing printing forms from a copy relief which includes, placing a back ing plate in a horizontal plane, flowing cellulosic over said backing plate, allowing said .cellulosic material to set, harden and freeze to the backing plate, placing a plastic mass upon the copy relief, and rolling said backing plate with the cellulosicmaterial attached thereto against said copy relief to spread the plastic mass therebetween.

7. The method of preparing printing forms from a copy relief which includes, placing a backing plate in a horizontal plane, flowing cellulosic material in solution over said backing plate, allowing said cellulosic material to set, harden and freeze to the backing plate to form a layer, placing a plastic mass of cellulosic material upon the copy relief, rolling said backing plate with the cellulosic material attached thereto against said copy relief to spread the plastic mass therebetween, allowing the plastic mass to harden and unite itself to said cellulosic layer and removing thethus molded plate from the copy relief.

8. The method of preparing forms from a photographically toned, copy relief which commass, and cold pressing said plate against the copy relief to spread said plastic mass therebetween, allowing the plastic mass to harden and uniteitself to said backing, and removing the thus molded plate from the copy relief.

-9. The method of preparing printing forms which comprises forming'a gelatine copy relief, juxtaposing a cellulose ester plate to the copy relief, interposing a viscous plastic mass of a cellulose ester between the plate and copy relief and rolling said plate into intimate contact with said copy relief, whereby said mass receives a fine impression of the copy relief, and maintaining the plate and copy relief. in contact until said mass has been transformed to the solid phase. p

10. In the procem of preparing printing forms, the steps of imposing a viscous plastic mass comprised of a cellulose derivative and a volatile solvent therefor upon a gelatine copy relief, by a rolling contact therebetween, maintaining the mass and the relief in contact until said volatile solvent has volatilized and the mass hardened, and thereafter removing the hardened plastic from the copy relief.

11. In the process of preparing printing forms from a gelatine copy relief, the steps that comprise placing a viscous plastic mass comprising a cellulosic derivative and a volatile solvent therefor upon the copy relief, applying a solid sheet of a cellulosic derivative over the plastic mass, cold rolling said sheet against said copy relief to spread the plastic mass therebetween, maintaining the sheet and copy relief in contact until the solvent of the plastic mass has volatilized and the mass has hardened and united itself to said plate, andthen' removing the thus molded plate from the. gelatine relief.

12. In the process of preparing printing forms from a gelatine copy relief, that has been developed, hardened and swollen with water, the steps that comprise placing a highly viscous so- .lution of a cellulose derivative in a volatile sollief.

13. The method of making printing forms from a copy relief which includes applying to said copy relief, near one end thereof, a relatively viscous mass comprised of a cellulose ester and a volatile solvent therefor, placing a backing sheet comprised of a cellulose ester thereover, and cold rolling the backing sheet against the plastic material while extenuating the surface of the material laterally so as to force the material into the interstices of the copy relief, and maintaining the backing sheet and copy relief in contact until the volatile solvent has volatilized and the plastic nrilassJ has autogenously bonded to the backing s ee I 14. A process of preparing printing forms which includes the steps of imposing a viscous mass of a cellulose ester and a volatile solvent upon a gelatine-copy relief by applying a backing sheet of a cellulosic material to the mass and progressively compressing the backing sheet against the copy relief by a rolling pressure.

15. The method of preparing printing forms from a photographically toned copy relief which includes, placing a viscous moldable mass upon the copy relief, applying a backing sheet formed from material which has an aflinity for said plastic mass over the plastic mass, and coldpressing said backing against the copy relief to spread said plastic mass therebetween, allowing the plastic mass toharden and unite itself to said backing, and removing the printing form from the copy relief.

16. The method of preparing printing forms which includes, forming a water-swollen gelatine copy relief, placing a backing in juxtaposition to the copy relief, interposing a viscous moldable mass between the backing and copy relief, and rolling said backing and said copy relief together whereby said mass receives a fineimpression of the copy relief, and maintaining the backing and copy relief with the plastic mass interposed therebetween in position until said mass has been transformed to a solid phase, and thereafter removing the copy relief.

17. In the process of preparing printing forms from a water-swollen gelatine copy relief, the steps that comprise placing a viscous moldable mass rendered plastic by the application of a solvent upon the copy relief, applying a solid backing sheet having an afiinity for said plastic mass over the plastic mass, cold-rolling said sheet against said copy relief to spread the plastic mass therebetween, maintaining the sheet and copy relief in contact until the solvent in the plastic mass is volatilized and the mass has hardened and united itself to said plate, and then removing the thus-embossed plate from the gelatine relief.

18. In the process of preparing printing forms from agelatine copy relief that has been developed, hardened and swollen with water, the steps that comprise providing a viscous moldable mass rendered moldableby a volatile solvent, placing said mass between the gelatine copy relief and a substantially non-stretchable backing, rolling said backing and gelatine copy relief to spread said plastic mass therebetween, maintaining the backing and copy relief in contact until the solvent is volatilized and the plastic mass has become hardened and bonded to the backing,

and then removing the copy relief from the printing form.

OSWA LD R. SCHULTZ.

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