US2042003A

US2042003A - Printing element and method of making same

Info

Publication number: US2042003A
Application number: US622051A
Authority: US
Inventors: William C Huebner
Original assignee: Individual
Current assignee: Individual
Priority date: 1932-07-12
Filing date: 1932-07-12
Publication date: 1936-05-26
Anticipated expiration: 1953-05-26

Description

May 26, 1936..

ffy M MM@ Patented May 2s, 193s UNITED 4STATES PATENT oFFicE GSAME William C. Huebner, Chicago, Ill. Application July 12, 1932, Serial No. 622,051 5 claims. v(el. i1-415) This invention relates to improvements in printing element and method of making same.

One object of my invention is to provide a printing element such as commonly termed a press plate, which will possess longer life than those heretofore known and whereby longer editions may be printed therefrom at less cost.

Another object of my invention is to provide a printing element of the character indicated in the preceding paragraph, which will have a printing surface composed of ink-receptive or retaining portions and ink-repellent portions and wherein the ink retaining portions are bonded to the metal sheet in a more tenacious and permanent manner than in press plates heretofore employed.

A further object of the invention is to provide a printing element in the form of a photographically prepared press plate, wherein the inkreceptive or retaining portions or areas of the surface, corresponding to the image to be printed, have an oxidized union or bond with the metal and the ink-repellent portions vor areas. of the surface are on non-oxidized portions of the metal.

Another object of my invention is to provide an improved process or method for preparing printing elements of the character indicated in the preceding paragraphs, the improved method or process insuring true, clear and sharp impressions.

Other objects of the invention will more clearly appear from the description and claims herein'- after following.

In the drawing forming a part of this specification, Figures l to 7 are more or less diagrammatic sectional views of portions of a printing plate illustrating several of the successive steps of the process of preparingvthe same, it being understood that the thicknesses are greatly exaggerated in order to better illustrate the invention. And Figure 8 is a cross sectional view of a portion of a. special form of plateembodying two outer layers of metal and an interposed resilient layer.

In carrying out my invention, a metal plate or sheet I0 of the desired'size is first obtained,

said sheet or plate being of any suitable metal such as steel, zinc, aluminum, copper and/or alloys. The metal plate may be either polished or with a very fine grain on the surface thereof and is thoroughly cleaned to remove any possible grease or other foreign matter. To clean the metal sheet, the same is preferably treated with a cleaning solution composed of one ounce of caustic potash to one gallon of water, followed by a solution of oneand one-half ounces of yhydrochloric acid to a gallon of water, the surfacefof the sheet being scrubbed, as with a brush, and thereafter rinsed clean with water. In this cleaning, the acid solution is used to neutralize the caustic solution.

' After thorough cleaning and rinsing and while still wet, a light-sensitive layer, film 'or coating I I is applied of any desired composition7 dependent upon different requirements, one such coating or l0 solution which I have found satisfactory being made up as follows. A solution of glue and water in the, proportions of six ounces of glue to twelve ounces of water is iirst combined with another solution comprised of water and flake albumen in the proportions of twelve ounces of water and two ounces of flake albumen. To the two solutions just described, after being thoroughly stirred and mixed, is added a third solution comprised of one and one-quarter ounces of ammonia dichromate and twelve ounces of water. This final solution, after being filtered, is preferably applied to the surface of the'metal sheet by placing the sheet in what is commonly known as a whirler4 and flooding the solution thereover while the sheet is being rotated. The sensitized coating or film is then permitted to set and dry thoroughly and is then ready for a photographic exposure.

A photographic printing ,plate or film of the image, design or subject matter to be printed, and whereon the image, design or subject matter is opaque, that is, the reverse of the usual negative, is made. With this photographic printing plate or lm, an exposure is made on the sensitized press plate While the two elements are in intimatel and uniform contact. The light acting on the sensitized layer or coating of the press plate, hardens those portions of the sensitized lm, rendering said portions insoluble in water, as will be understood, and leaving those portions of the light-sensitive film corresponding to the image, design or subject matter, soft and soluble in water. Such exposure, depending upon the characteristics of the light-sensitive film or coating and the intensity of the light source employed, may be from approximately eighteen seconds to one minute. I

After the press plate has thus been subjected to the light action, the press plate is .treated first by iiooding the entire plate with water and then with running water, preferably in a trough, to remove those portions of the light-sensitive film which were not acted upon by the' light and which correspond to the image,`design or subject matter to be printed and as indicated by the spaces or gaps I2-I2 in Flgure 1. For simplification in the description and claims, the term image will be use hereinafter to include any picture, design, writte matter yand/or any other subject matter which it may be desired to have printed.

After the press plate has been thoroughly washed after exposure, it is then given a bath in an ammonia solution preferably consisting of one ounce of ammonia to one gallon -of water, thus rendering those light-hardened, Yexposed portions of the illm on the press plate, receptive to a dye solution. y

After the ammonia bath, a dye solution is flowed over the plate, such dye solutiony being of suitable color and composition, one such solution which I have found satisfactory consisting of one quart of water and one ounce of dye such as methyl violet. The dye solution adheres to the retained, light hardened or non-image portions I I of the film surface on the press plate, thus setting off and rendering clearly visible the clean portions o r areas I2 (non-dyed) of the press plate surface corresponding to the desired image. l

The entire surface of the press plate is now gone over with a solution preferably consisting of one gallon of water, and two Aounces of bicarbonate of soda. The application of this solution, which is preferably applied with a cotton wad soaked in the solution, further cleans the plate, removing any glue or thev like from the finer portions of the image areas which were not removed by the original water washing. The press plate now is in a condition where all details of the image to be printed, are represented by the thoroughly cleaned metal surface of the press plate and which Were originally protected from the light action by the opaque areas of the printing plate or llm corresponding to the desired image.

The press plate, afterthe application of the dye solution and cleaning, as above mentioned, is then dried as quickly as possible by blotting the surface with news print paper and drying with an air blast. When thoroughly dry, any areas or portions of the press plate which are not to carry any printing (such as margins or borders) may be stopped out with a thickened sensitized solution similar to thatinitially used in sensitizing the plate or sheet but wherein the glue content is preferably increased approximately 100%. The thicker glue sensitizing solution is applied in this instance, preferably by brush, on such portion or area (as for instance the borders or margins) where printing is not desired. When the light-sensitive solution is set and dried, the plate is again exposed generally to light action, thus hardening the last applied light-sensitive solution which is thus rendered insoluble in water.

The plate is now in a position to be intaglio etched, then oxidized, and have the ink receptive compound bonded thereon. To accomplish this the following procedure is employed.

'I'he image or bare metal areas of the plate are now intaglio etched as indicated at I3-I 3 in Figure 2 and a satisfactory solution therefor is made up of eight ounces of perchloride of iron at 47 Baum mixed thoroughly with a half ounce of nitric acid. This solution or mixture must be applied immediately after mixing, winch is done by spreading the solution over the plate uniformly as by means of a rubber set camel hair brush or by floating over the plate with suitable apparatus designed therefor. The etching solution is allowed to act on the image areas tof the-plate for a short time, say twenty to thirty seconds, whereupon the plate is immediately blotted with a large sheet of blotting paper and/or flooded with bicarbonated water solution'and thoroughly rinsed to remove the etching solution as quickly as poslsible. The plate is then drained and blotted with clean news print paper and dried quickly by air blast, care being taken to make the drying complete. Upon completion of the drying, the plate is next hand wiped thoroughly with a soft cloth ball.'

preferably cheesecloth, to remove any loose, dry iron oxidized particles that may cling to the image areasof the plate or the plate can be wiped withany suitable solvent such as acetone, alcohol, etc.

The next and extremely important step of the process is the oxidization of the image areas' just etched and the application and bonding or unionization thereto of the ink-receptive compound. The latter, while capable of considerable variation, depending upon conditions such as the character of inks subsequently to be employed in printing, must nevertheless embody several necessary qualities. First, the ink-receptive compound must be such that, after oxidization and application of the oxidized bonding compounds to the plate, lt will be able to resist without deterioration, the caustic potash and/or acid solutions subsequently employed on the plate to remove the non-image f area portions of the sensitized film, as hereinafter explained. Secondly, the compound must be perfectly receptive to the greasy ink for subsequent printing in the press and, finally, the compound must be such as to eifectuate oxidization of the etched or image areas of the plate while effectuating a bond or union of the greasy ingredients of the compound with the oxidized metal in order to obtain a permanent, tenacious grip or union that will insure long printing life of the plate in the printing press.

To obtain the above indicated desired results, any solution or mixture which liberates oxygen freely when drying slowly in the intaglio etched image areas I3 is applied to produce a grease receptive oxide. One such solution or mixture found satisfactory in the average situation comprises a solution of potassium chlorate and water in the proportions of one sixteenth ounce to thirty-two ounces respectively, which is preferably applied by flowing the same over the surface of the plate immediately followed by owing an acid solution within the intaglio image areas of the plate as indicated by the dash lines I4 in Figure 3, and the oxide thus formed constitutes what may be termed the first formed layer of an oxidized bond between the base metal of the plate and the nal complete y ink-receptive coating on the image areas.

After the plate is dried, anoxidizing bonding solution or mixture is applied. Such solution or mixture should comprise any greasy substance or compound which will unite with the oxidized areas above referred to and which will dry and oxidize to a degree sufficient to resist caustic potash solution or acid solutions and which will also produce a satisfactory base that will be ink-receptive when the platel is inked up in the printing press. Such an oxidizing solution or mixture found satisfactory may be composed of a mixture of tar oil or oils derived from coal tar bases which are mixed `with oxidizing agents such as red lead, litharge,

manganese dioxide, manganese borate o r other similar well known oxidizers used in printing inks, A satis actory mixture may consist of:

Ounces Red lead $41 Coal tar creosote 1 Coal tar oil $4; Carbolic acid nl,

A suitable tar oil in the immediately preceding formula is Long F Pitch. 'I'his compound is preferably applied by rubbing the same into said previously oxidized image areas on the plate and then allowed to dry, thus completing what may be termed the nal oxidized bonded coating over the image areas as indicated at [6in Figure 5.

A coating of asphaltum is then rubbed on the plate over which in turn is applied a coating composed of parailin wax and paraflin oil and which is rubbed down smooth. These coatings obviously provide a protective media to resist the caustic potash solution subsequently employed, as hereinafter described. The image reproducing areas of the plate are now provided with an ink-receptive and water and acid repellent compound tenaciously and permanently bonded or intimately coaies'ced with and united to the base metal of the plate.

The plate is next flooded with a caustic potash solution, preferably consisting of one gallon of water, one ounce of caustic potash and one ounce of ammonia. This solution is spread by means of a suitable brush over the entire surface of the plate until the light-hardened or non-image areas of the sensitized lm become soft, whereupon the plate is scrubbed as with a soft brush, then iiushed with running water to remove any remaining caustic potash solution and most of the softened sensitized film. The complete removal of the light-hardened or non-image area portions of the sensitized lm is effected by iiooding the plate with a solution consisting, preferably, of one gallon of water and one ounce of hydrochloric acid and during which the plate is again brushed over with a suitable brush or with a wad of heavy liannel to remove the finer traces of the light-hardened portions of the sensitized film. The press plate is then in the condition where the image areas I6 thereon with the ink-receptive coating or compound stand out in clear and sharp contrast and relief from the remaining non-image portions or .areas of the plate as shown in Figure 6, which are clean and free of any coating or film.

The press plate is next treated with any suitable desensitizing etch, such as satisfactory etch consisting of one half ounce of phosphoric acid and thirty-two (32) ounces of gum arabic solution, testing approximately forty per cent (40%) on a water hydrometer. A

After the application of the desensitizing etch. the plate is washed with running water and thereafter preferably gummed up and rubbeddown smooth and fanned dry, with the plate having a ush coating comprised of image ink-receptive areas I 8 and non-image, ink-repellant areas, I1, as illustrated in Figure '1.

The plate is now ready to be run in the press. If, as for instance in changing from the use of a ldark to a light colored ink, the resists are removed from the image areas by suitable solvents, nevertheless the image areas retain the oxides formed therein and chemically bonded to the base metal and are still receptive to-all greasy inks and will continue to print becau of the tenacious grease receptive bond with the base metal, a result never heretofore obtained so far as I am aware.

In the preceding decription, I have set forth with particularity various solutions, mixtures and compounds and a detailed sequence of steps employed in connection therewith which I have found extremely satisfactory in actual practice under average conditions. As will be obvious to those skilled in the art, a wide range of variations is permissible both as to the actual ingredients used and percentages of ingredients entering into said solution, coatings and mixtures without, however, departing fromthe essential features of the invention, such variations referred to sometimes being found desirable on account may be employed and different metals of which the press plate may be composed.

In certain instances requiring especially` fine work, it is desirable to start with a press plate having a smooth polish iinish in order that the etching of the image areas may be absolutely uniform while at the same time it may be advantageous to have the non-image areas of the plate when ready for the press, roughened or grained. This may be accomplished in carrying out my invention by roughening or graining the non-image areas of the plate after the reversing of the image areas has been completed. by subjecting said nonimage areas of the plate to a suitable acid and a basic salt, depending upon the base metal in the press plate. I am aware also that the oxidized bonded image areas on the press plate may be obtained without deep etching said image areas, the oxidized image areas being formed on the original surface of the press plate after the image areas of th'e light-sensitive film have been removed 'and without etching. It is also possible to etch the image areas of the plate to produce the intaglio effect, when desired, by electrolytic action on such image areas after the corresponding portions of the light-'sensitive film have been removed and the non-image areas suitably protected against electrolytic action. Another variation is to produce an oxidized image area intaglio eiect without actually intaglio etching of the press plate metal, by electrolytic action as, for instance, by producing the oxidized bonded image areas on the plain surface of the press plate metal without etching and, after the reversing step, depositing metal on the non-image areas of the plate electrolytically immediately after the drying of the plate and removal of the light hardened portions of the light sensitive film. Various other changes and modifications all within the purview of the inventionvwill be evident to those skilled in the art.

In the preceding description, I have confined the same to the preparation of the surface of a single sheet of metal used as a press plate. The invention is equally applicable to both sides of a special yieldable printing plate such as shown in ,Figure 8 wherein two thin sheets of metal 20`20 have interposed therebetween and united thereto, an intermediate layer o f rubber 2l. In this special form ofpress plate, the metal sheets, grained or polished, may be about /.1000 of an inch or less in thickness and the intermediate rubber layer about al, of an inch. Such a specially formed press plate possesses numerous advantages in that, on account of the thinness of the outer metal plates or sheets with the rubber backing the prepared printing surface will yield as much as may be necessary to compensate for irregularities or variations in the-paper being the preferred manner of carrying out my invention, but the sameis merely illustrative and I" contemplate all changes and modifications that come within the scope of the claims appended hereto.

I claim:

1. The herein described method of preparing a press plate which includes: removing the image areas of an exposed sensitized lm coating from the surface of a metal plate; intaglio etching said image areas; oxidizing said image areas; applying an oxidizing mixture to the then oxidized image areas; and applying to said image areas an oxidizing, ink-receptive compound. l

2. In the method of producing an ink printing element having a metal base, the improvement which includes: applying to predetermined image areas of the surface of Ithe metal plate, an oxidizing agent and by the chemical action between said agent and metal plate, creating'a greasereceptive oxide, in situ, in said image areas; applying to said grease-receptive oxidized image areas, a greasy, oxidizable compound containing an; oxidizing agent and by the` chemical action thereof uniting, in situ, the compound with said Qan oxidizing agent and, by the resulting chemical action, creating a grease-receptive oxide, in

oxidized image areas by further oxidization; and then applying to said image areas an oxidizable ink-receptive mixture containing an oxidizing agent and by chemical action thereof uniting the mixture, in situ, with the previously formed 5 oxides. l

3. In the method of producing an ink printing element having a metal base plate, the improvement which includes: etching predetermined image areas of the surface of the metal 10 plate and thoroughly removing-all oxides produced by the etching; then applying an oxidizing agent to said cleaned, etched image areas and by the-resultant chemical action producing a grease receptive oxide, in`situ, in said image areas i then l5 applying to said grease receptive oxidized image areas, a greasy, oxidizable compound containingan oxidizing agent and, by the resultant chemical action, uniting, in situ, said compound with the previously formed oxides; .and finally apply- 'ing to the oxidized areas, an oxidizable inkreceptive mixture containing an oxidizing agent and, by the resulting chemical action, uniting the mixture, in situ, with the previously formed oxides.

4. In the method of producing an ink printing' element havinga metal base plate, the improvement which includes: applying to predetermined image areas of the surface of the metal plate,

situ, in said image areas; and thereafter applying to the grease-receptive oxidized image areas, oxidizable, greasy and ink-receptive substances containing oxidizing agents and, by the resulting chemical reactions, uniting said substances, in situ, with said ilrst mentioned grease receptive oxide formed by said oxidizing agent.

5. A printing element-including a metal base plate and the surface 'of which is provided with '40 a coating comprised of both ink-'retaining and ink-repelling portions, these portions of the plate corresponding to the ink-retaining portions of the coating being oxidized and said ink-retaining portions of the coating including oxidized greasereceptive and ink-receptive substances and in which the oxides are coalesced with the metal oxide of the base plate.

' c. HUEBNER. 50