US1346885A - Process of preparing printing-plates - Google Patents

Description

A. J. HAIN.

.PROCESS 0F PREPARING PRINTING PLATES.

APPLICATION FILEI.` JUNE Il, I9I7.`

v1,846,885. PatentedJuly 20,1920.

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Y UNITED i STATE-s -PaxrENT OFFICE.

' ALBERT J. HAIN, .oF LAKEWOOD, omo. i Y

I PRocEss or PREPARING PRINTING-maries To all whom t may concern.'

Be it known that I, ALBERT J zen of the United' States, residing at wood, in the county of Cuyahoga and State of Ohio, have invented certain new and use- HAIN citiful Improvements in Processes of Preparingl Printing-Plates, of which the following is a specification.

This invention relates to a process of preparing printing plates, and more especially printing plates of the half tone variety such as are use 1n newspaper, magazine and like Q less apparatus and requiringl a minimum work for printing reproductions of photos,

cuts and the like.I

The object of the invention is to provide an improved process which is simple and does away with considerable of the apparatus, such as cameras, screens and the like usually employed in process work, therebyenabling the proper effects to be obtained with amount of skill,and adapting the process to bev performed, for example, in smalll printing plants -or by amateurs without employment of the apparatus customarily found in fully equipped plants for this purpose.

Further objects of the invention are in part obvious and in in detail hereinafter..

The invention Icomprises the severalprocess steps hereinafter described and claimed.

In the drawings Figure 'l represents a diagrammatic cross sectlonal view, enlarged,

illustrating the preparation of a pla-te' for printing by one speclfic process embodyingthe invention; Fig. 2 is aplan view,illustrating the treatment of and effect upon the isolated protecting areas; and E1gs. 3 and 4 I are diagrammaticsectional views, enlarged,

illustrating other specific ways .of carrying out the invention.

,` of the image to: be printe and will be of greater area or higher value where the icture is shaded or darker v than at theV hi'g er lights. This plate is usually formed by Specification of Letters Patent.

flake# part will appear more.

Patented July 20,1920.

Application feed June 11, 1917. serial N6. 174,649.

etching a smooth surfaced metal plate, such as a zinc plate, the etching eiiect being limited to certain areas by the formation upon the plate of a resist which prevents the etching fluid from attackin 4the plate at theareas to be unaected. he particular purpose ofthe present invention is to provide an unproved method or process of building up upon the plate in skeleton form the' proper resist to confine the .action of the iuld to certain `desired 4.areas andI etchin prohiblt its action upon other areas.

Briefly stated, therefore, the invention coni I sists` in rst 'forming upon theplate to -be etched aseries of closely and uniformly plate from .the action of the etching fluid, and subsequently treating said spaced prowith variations in t e lights-and shadows of spaced protecting areas, all of uniform size, 'adapted inrone way or another to protect the' the image, as a consequence of which the -I i plate finally produced, when used as a printing plate, will reproduce the light and shadow effects of the image..

The invention, therefore, Aproceeds from an initi al step of first Vforming this series-of` uniformly spaced protecting'areas of uniform size.

aid areas shouldpreferably be of what maybe termed minimum size', as

they are usually not reduced insize bya subsequent step and will therefore` produce their counterpart'dots or stipples even in the highest lights of the image, except as their size effect Amay be dimimshed by undercutting action ,of the etchingI fluid. The protecting other words. they `do not merge intol each other, at least so far as their protecting effect upon the 'plate is concerned, thereby enabling them to be built up or enlarged radially in all areas are also isolatedfromeachothen In directions. Nevertheless, they may be part and parcel of thejsame layer', lin or stratum, dii'erent portions `,of which. are' affected in different ways to form risolated protecting areas'on the one handfand intervening areas which do .not have the otherhand.

The isolated protecting areas may be formed directly upon the surface of the plate tobe-etched and themselves have the quality I i vof preventlng action on the plate by the etching fluid.v On. the other hand, it issometimes more convenient to first cover the plate `with' a -layerofa resist which will protect4 the plate 'from' acid, and upon said resist4 a protecting effect', im

tectmg areas, to vary their size in accordance applying isolated protecting areas of a material which will serve as a resist to a reagent for attacking the substratum or initial resist layer. In this case the isolated protecting areas are formed and built up according to the lights and shadows of the image, then used t9 protect areas of the substratum while attacking the intervening areas, thereby exposingl or opening up through the substratum the metal of the base 4plate to attack by the etching fluid, or even to permit attack of the base plate through the unaffected intervening areas Without disturbing them.

The character of resists and reagents'used is immaterial so long as the foregoing effects are obtained by the means and in the manner specified, but to more completely set forth the inventionand purely for the purposes of illustration, I will now vdescribe several methods employing the invention.

According to the firstmethod the plate to be etched, which may be of zinc or'some other well known material for this purpose and which is indicated lat l, is first covered with a layer 2 of a material resistant to the particular etching fluid to be used, such as an acid-resist. This acid resist may be of any suitable material several of which are wellknown, for example, gum dammar, gum shellac, bitumen, dragons blood, or copper platen In the present instance, however, we will assume that the resist is copper plate upon the surface of the zinc.

Over the 'copper resist is applied a film 3 of a colloid or emulsion, such as gelatin or the like. After this film has been treated the plate is immersed in a suitable sensitizing solution, preferably one containing salts' of manganese. One solution suitable for the purpose is as follows:

c Solution Af Saturated solution potassium bichromate 5 drams. Manganous sulfate 44 grains. Manganous chlorid 22 grains. Aluminum sulfatemv. l0 grains. Water to make lounces.

Aspaced isolated areas 4, shown considerably enlarged in Fig. 1, of minimum uniform size and of hardened colloid material, in a continuous layer wlth ntervenmg areas 5 of unaffected unhardened colloid material. At the 'Sametime exposure to light produces'a chemical effect upon the reagents in the sensitized film so that the isolated areas 4 of the hardened colloid are impregnated with an insoluble manganous oxid. The exposed plate is then vwashed for three minutes, more 1 or less, incold water, or untilall the .soluble unaffected bichromate and manganous salts are washed out. The cold water does not affect the colloid itself. f

The plate, produced as above described, is

silver, such for instance as a print which has been obtained, in the well known manner,

with a silver bromid emulsion. Such a .print is immersed in a suitable reducing solution, for example as follows Solution B.

Copper sulfate 96 grains. Potassium bromid 48 grains. VVater 7 2 ounces.

When the image is fully bleached the print is well` washed with water and is immersed for a minute in a solution as follows:

l The print, thus prepared, and indicated at 6, is then brought into close'contact with the treated colloid surface of the plate to be y used in connection with a print 4in metallic etched, the contact being maintained for some time, say about twenty minutes, after which the print is removed.

1 The effect of the contact treatment is to"l cause the manganous oXid in the isolated protecting areas of the colloid film to oxidize and render insoluble the surrounding tis-- sues of the colloid film, as at 7, in proportion to the amount of silver in the original print to be reproduced. In other words, where, in the original print a maximum amount of silver existed, as at a deep shadow, the maximum amount of hardening action has extended into the tissues of the colloid surrounding the several. isolated protecting areas in'that neighborhood of the print being formed; where there was little or no silver in the original print, as at a high light, there is little or no hardening action in the print being formed and the'isolated areas in that neighborhood are unaffected.

The plate is next dried, alcohol being used to assist the action,.if desired, and is immersed in a solution of ferric chlorid 42o Baume, which quickly penetrates the colloid whereit has not been hardened or renready for etching with a suitable acid, such as nitric acid diluted in water.

If an acid resisting substratum, such for vfrom contact with the plate the soluble colloid may be washed out with hot water, thus exposing the -acid resisting substratum, which is removed, where unprotected, by a A, suitable solvent, such as alcohol. for shellac or turpentine for asphalt, whereupon the plate is etched with acid as before.

Up to this point I have described the formation of what may be termed a built up skeleton of the image upon a resisting substratum, and the removal of the unprotected areas of the substratum to expose the base plate for'etching. The same kind of a built up skeleton image in gelatin may be formed directly" on the surface to be etched, which may be zinc, copper or the like, and then metal plate to convert it into a protecting enamel, so` that the burned skeleton image itself becomes a resist for the etching fluid.

This does away with the additional resisting substratum'and the built up protecting areas themselves become the resist, as before stated. l

In the first method described the uniform isolated protecting areas of, minimum size are built upfor increased in size in varying V- amounts according to the lights and shadows of the image by the effect of the'- silver inthe bromid Vprint upon the manganous oxid in the isolated areas, and the hardening action of the twoupon the neighboring colloid I tissues, but it is not essential that the silver for producing this action be in a print brought into-contact or juxtaposition with the colloid of the plate. The silver may be embodied in various ways in the plate itself,

thereby rendering the plate'suitable for direct exposure to they action 'of light under anegative or in a camera. A -method of this kindffor example, would be practised4 as fol- Upon the plate to be etched, indicated at 10, Fig. 3, is placed a suitableacid resist-4 I ing substratum or'layer' 11. ,Theres'ist' for this specific illustration may be assumed to be compounded as follows Resist X Syrian asphalt-; 1 ounce.

enzol l5 ounces.

Cil of lavender-; 1 dram.

Turpentine 1` dram. l

Upon the' resist are formed a seriesof closely and uniformly spaced isolated protecting areas of. uniformminifnum size,'in

dicated at 12, in which ,may be incorporated manganous oxid by the use of a solution,

.This colloid film when dried is sensitized by immersion three minutes in Soluton A, and, when dried, is exposed beneath a high-light photo engravers screen until the light has rendered insoluble those uniformly spaced minimum sized areas exposed to the light. -The solubleA portion of the film isthen washed out in warm water, leaving upon the plate the isolated protecting areas 12,'in-V soluble and impregnated with manganous oxid;

The plate is then flowed with an emulsion ll 'dfil 13 't' f i f said skeleton image may be burned into the. or CO O1 m o sensl we Crm Pre er `ably containing a silver salt, such as silver bromid. One suitable. sensitized film for this purpose is compounded as follows z- Gelatin grains. Ammonium bromid 30 grains. Water 1 ounce.

Silver nitrate, 30 grains dissolved in 1 ounce of water.

vany suitabledeveloping agent yand is fixed 1n a mixture of sodium thiosulfate (hypo7), after which the salaam D.,

lPotassium ferricyanid 5 grains, Potassium bromid 20 grains.

to render the gelatin emulsion or colloid insoluble or hard inv the. presence of silver bromid where in contact `with the oxidized isolated protecting areas surrounded by said .10ctplate is immersed in a solutlon as follows l ounce. f

colloid film, as at 14, the effect being'infproi portion to the exposure of each area and the deposit of silver bromid remaining in the sensitized film in the neighborhood of such area.

ter. The acid resisting substratum, where unprotected -by the remaining gelatin is dissolved in asuitable solvent, such as vturpentine', and the plate is etched with, a suitable etching medium, such as a solution of nitric acid in Water incase the basematerial of In this lastv method' the silver deposit is After this treatment the solublel filmin the intervening spaces 15' betweenl the l isolated areas'is washed out with warm waa created in the body offthesensitized colloid film'superposed upon previously formed isoy follows pon the plate to beietched, indicated at 20, Fig.v 4, is placed a layer 21 of a suitable resist, vsuch as Resist X' before mentioned.

, Water Upon this resist are formed the isolated protecting areas, in which may be incorporated a light sensitive element. lThis may be accomplished as follows A colloid film, such as the collod or emulsion M before referred to, isvfiowed over the plate andv dried, after which it lis sensitized by immersion three minutes in the following solution v Salaam E.

Potassium bichromate 10 grains.l Water 1 ounce.

The plate when' dry is exposed beneath a high light photo engravers screen to harden the exposed areas 22, the soluble portions of the film being then Washed out in water. The plate is then immersed in a Solution as follows :5-

Solution F. l

Potassium bromid `30 grains. Acetic acid 1 drop. Water v 1ounce.

The plate is then dried and immersed in` a`r solution as follows i' Solution, G.

Silver nitrate y 30 grains. Citric acid 5 grains. 'Distilled water- 1 ounce.

This treatment directly sensitizes with silver bromid the isolated protecting areas 22, which are formed vof `a colloid film. The protecting areas are then furnished with a surrounding body from whose tissues they may be Lsubsequently built up in accordance with the lights and shadows of the image,

for which purpose the plate is flowed with a simple emulsion orcolloid film 23, composed, for examplefas follows Gelatin grains.

1 ounce.

y The plate, thus treated, isexposed beneath a hotogra )hic ne ative or for some ur- P an l a a poses, in a camera, and is developed and liXed as usual. y

The plate is then treated by any suitable method to obtain the image in halftone dot form upon the acid resisting substratum. Two such methods may be described for purposes of illustration. The first method is as follows FIRST' METHOD.

T he plate isflowed with a solution as follows :e

Solution H.

Pyrogallic acid 3 grains. Citric acid 3 grains'. Water 2 ounces. A 20-grain silver nitrate solution 15 drops.

This solution serves as an intensifier, increasing the deposit of metallic silver upon the vexposed isolated protecting areas in accordance with the. amount of silver already present in such areas. In other words, 1n an area containing no silver there is no further or additional deposit, but in all areas vcontaining silver the additional silver deposit is in proportion to the amount already present. The plate is then immersed'in a 10%v solution of vpotassium bichromate, which hardens the gelatin in the presence of the v metallic silVer,-and at the same time builds up and increases the size of the isolated protectingareas iny accordance with the amount of' silver deposit thereon, and therefore in accordance with the lights and shadows of the image. The soluble gelatin is then washed out with warm water, the acid resisting substratum is dissolved with turpen-- tine and the plate is etched as before.

SECOND ME'rHoD. The plate, prepared with the light sensi.-

tive isolated areas thereon, may be immersedI r ina solution as' follows y f Solution I j Potassium bromid 20 grains. Potassium ferricyanid 5 grains. Potassium bichromate .10 grains. y Water 1 ounce.

The purpose and effect of this solution are to tive isolated areas and the solution, which makes insoluble the tissuesvof the plain colloid film neighboringsuch areasl and in direct proportion'to the amount'of silver 'con-L tained in such. areas'. The soluble gelatinl is then washed out in` warmwater, the acid resisting substratum' is dissolved and the plate is etched, as before. Whilein the specification vI have diescribed a number of specific methods employed in the practice of theinve'ntion, it

produce a chemical reaction between the metallic silver deposited in the light sensif` is of course to be understood that the method is capable of considerable modification, within the scope vof the appended claims, without departing ,from thespirit of the invention, and is therefore not limited to the specific methods described. rlllhe in.

vention can bel'carried out with simple :ippaiatus and therefore enables plates of this kind to be prepared by amateurs or in small printing shops without a complete photol readily understood.

What I claim is l. The method of preparing plates for printing reproductions ofV an image, consisting in forming upon a plate uniform isolated protecting areas of minimum size, and increasing the size of-said areas in every region of the plate in accordance with thel value of. the light or shadow inl that region of the image to be reproduced. v

2. The@ method of preparing plates for printing reproductions of an image, consisting in forming upon a plate uniform isolated protecting areas of minimumsize' surrounded by. neighboring material, and increasing the size of said isolated areas by acy cretioii from said material in every region of the plate in accordance with the Vvalue of the lightA or shadow in that region of the image 'to be reproduced.

3. rlhe method-of preparing plates for printing reproductions of an image consisting in `forming upon a plate uniform-isolated protecting areas of minimum size surrounded by neighboring tissues, increasing the size of said isolated areas by accretion from said tissues in every region of the plate in accordance with the value of the light or shadow in that region of the image to be reproduced, and treating the remaining intervening non-projecting areas to expose the' plate to the action of an etching fluid.

ll. The 4method of preparing plates for printing reproductions .of an image, consisting in depositing upon a plate a uniform continuous layer-of a material resistant to an etching fluid, super-posing upon said layer a series o of minimum size, increasing they size of said A areas in every region of the plate in accordance with the value of the light or shadow in that region vof the image`to be reproduced, and dissolving the layer of resist where exposed between the built up isolated: protecting. areas.

In testimony. whereof I afliz;v my signature.

' ALBERT J. HAIN..

uniform isolated protecting areas n

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