US1849598A - Printing plate and method of making the same - Google Patents

Description

March 15, 1932. .1L-r. slMMs E'r Al. 1,849,598

' PRINTING PLATE AND METHOD 0F MAKNG THE SAME Filed Nov. 26,` 1928 Pateiited Mar. 15, 1932 UNITED STATES .PATENT OFFICE JAMES T. SIMMS AND GEORGE A. SIMMS, 0F CHICAGO, ILLINOIS, ASSIGNORS, BY MESNE ASSIGNMENTS, TO BURTON R. HERRING, OF CHICAGO, ILLINOIS PRINTING PLATE AND METHOD OF MAKING TILE Application led November 26,v 1928. Serial No. 321,817.

Our invention which relates to a printing plate and a method of producing the same, is concerned more particularly with a treatment applied to the impression surface of such a plate by which it is rendered suitable for printing with water-soluble inks. In accomplishing this end, we preserve all the sharpness of definition and accuracy of the Well-known printing plates, such as commonly use oil-soluble inks. p

It is a primary object of this invention to produce a printing plate of the character described by mechanical means with a minimum of operations and expense. The term printing plate, as used herein, will include original zinc or copper etchings executed either by hand or by well-known processes; electrotypes or steel-faced plates produced and/or treated by any of the processes which enhance durability of the original plate or duplicates thereof; and linoleum or composition plates, other than rubber, which are cut by hand or machine. It is to printing plates answering generally to the preceding de` scription, that the present treatment may be applied. y

According to our invention, a thin sheet of india rubber is applied over and adhered to.

the impression surface of a printing plate. By the term india rubber, we refer to suit able mixtures having a aoutchouc base, it being a requirement that such mixture when vulcanized will present a surface over which eitherv water, oil, and/or alcohol soluble inks may be distributed in a manner suitable for printing purposes. A rubber facing adaptable for this process may have a thickness of .006 to .025 inches. Heavier facings may be used, but only for purposes where a fine result is not essential, 'such as in the prepara'- tion of linoleum or composition plates to be employed for printing boxes and other grosser work. A material known as gutta percha may be used in certain cases.

A printing plate having its impression surface covered with such a facing which is adhered to the plate at every point is adapted admirably for printing with water-soluble inks: It will endure through a. prolonged service, and will seldom require renewal or replacement. The, process of applying the facing to the plate is performed mechanically so as tov ensure uniform and accurate results in every case.

In the drawings we have illustrated fourl views in which#- Figure 1 is a vertical section through the impression assembly as it appears while undergoing pressure;

Fig. 2 is a fragmentary enlarged-section through the impression assembly;

Fig. 3 is a fragmentary enlarged view through the finished plate; and

Fig. 4 which is a view similar to Fig. 3 shows a plate of modified form to which a facing is applied in a slightly different manner.

For purposes of illustration we have shown an original printing plate 10 mounted upon the usual base 11 which may be wood, metal, or other material. The plate illustrated in Figs. 1 to 3 is formed with a plurality of vents 12 communicating with depressed portions thereof to relieve .the air trapped therein when the facing material ifspressed tightly against its impression vsurace.

The impression surface of the printing plate is thoroughly cleansed of grease and other foreign matter, as by wiping the same with alcohol, benzol or the like. When the plate is dry, a suitable adhesive 13 is applied to its impression surface. This adhesive may desirably have an asphaltum base.

For some work it may be advisable to remove most of the adhesive from the elevations forming the actual printing surfaces which are' impressed against the paper. This is done conveniently with a felt wiper wetted with a suitable solvent for the adhesive elnployed. When the adhesive becomes tacky the facing material is .applied thereto. In the form shown, this comprises a thin sheet of uncured india rubber 14 which has previously been carefully and evenly laid rover a resilient cushion 15. Such a cushion may advantageously consist of laminations suchv as a pile of rubber sheets, the engaging surfaces of which are lubricated at 16 as by dusting with talcum powder or the like.v By this treatment, the several laminations are rendered suciently slippery to slide relatively to each other and to the facing material 14, as required, thereby enabling the latter to conform to every irregularity in the impression surface of the printing plate. The resilient cushion is desirably rested upon a smooth metal plate 17, being retained in place thereon by a clamp 18, which engages with one edge thereof.

The impression assembly includes the base plate 17, the resilient cushion 15, the sheet of facing material 14, and the printing plate 10 Whose impression surface, with adhesive in the tacky stage, is presented to the facing' material. IThe entire assembly is then placed between pressure blocks 19 and 20 of a hydraulic or other suitable press. In response to the pressure delivered by the press to the impression assembly, the facing material, being the uncured rubber sheet 14, is conformed firmly and intimately over the impression surface of the printing plate 10, as shown in F ig. 3; and the intervening coating of adhesive 13 serves during this pressure treatment to unite the facing inseparably and closely to the plate. the resulting product being a continuous facing 21 (see Fig. 3) conforming exactly to every irregularity in the impression surface of the printing plate. rlhe blocks which bear against the printing plate should be of such material as to facilitatezthe escape of air which is released through the vents 12.

The resilient cushion which underlies the facing material during the interval that pressure is applied thereto is preferably built up of thin laminations such as sheets of rubber having a suitable lubricant between their engaging surfaces. With such a. construction the cushion may yield in the direction of the pressure force which is applied, and also may slide laterally as required by the stretching of the facing material during its adjustment to the irregularities in the impression surface of the printing plate. The resultis that the pressure applied against the facing material during this stage of the operation is directed over every point, including the depressions as well as the elevations, of the im' pression surface of the printing plate, so as to form an intimate union over the entire area, thereof.

The facing material, after being adhered to the printing plate may be trimmed around its edges, and is then vulcanized in any welllmown manner as by dipping the plate briefly in a suitable vulcanizing solution` such as sulphur chloride in carbon tetrachloride. llf

desired, this solution may be poured over the plate. After the facing has become cured, a coating of topping varnish, such as asphaltum varnish, is desirably applied to the major depressed portions of the printing plate, so

that the roller of the printing press will not contact with such portion.

Although vents'lQ are shown in Figs. 1 and 2 for the purpose of permitting the escape of air which may be entrapped between the surface lm or skin of plastic material and the preformed printing plate, it may be desirable, under certain conditions, to vary the process of applying pressure by the resilient cushion, as above described, in order to insure positive and intimate contact of the surface skin at every point on the plate. It has been found that if the pressure is withdrawn after a short interval of time and then reapplied in the manner described below in the description of Fig. 4f, that perfect contact is established atall points.

In Fig. 4 we have shown a conventional electrotype plate 10 which differs from the printing plate elsewhere illustrated in one respect only, Viz., it is lacking altogether in any vents for the escape of trapped air. It is possible, however, to utilize our invention in theapplication of a-rubber facing 14 to the impression surface of such a plate. ln the accomplishment of this end a relatively light pressure is first applied by the resilient cush ion to the rubber facing after being placed over the impression surface of the printing plate. This pressure is continued for a short time onlya minute or less-and the cushion is then withdrawn from pressure contact for a brief interval.

rllhis first application of pressure causes the facing material to conform in large measure to the irregularities in the plate, although the trapped air may prevent the rubber facing from advancing the full distance into the depressed portions thereof, as represented in Fig. 4f. The facing sheet which is porous to some extent is rendered still more so when stretched into conformation with the irregularities of the printing plate, and would permit escape through the pores of the air which is trapped within the depressions, provided that the resilient cushion would not interfere. rfhis interference to such escape of air through the facing material is removed when the cushion is withdrawn momentarily from pressure contact. The air being then re lieved, a. further and greater pressure is applied for another minute or less. This last pressure operation causes the facing material to advance the full distance into the depressions so that adherence to every point of the impression Surface of the printing plate is assured.

Among the advantages derived from our invention are the following: The printing plate having a rubber facing applied to its impression surface in the manner described. retains all of its original sharpness of definition. Such a plate, or any desired num ber of duplicate plates, may be treated according to the present process, and the resulting impression surface will be uniform in all cases. This is due in large measure to the fact that all operations are mechanical, and do not depend in any degree upon the skill of the operator for the results obtained. The facing material is applied directly to the original printing plate which becomes in a single operation the finished printing plate with a facing material applied to its impression surface so as t0 render the same suitable for use with inks which are water-soluble or otherwise. Due to the means employed for venting the trapped air it is possible for the facing material to unite-with the plate at every point, including the depressed portions thereof, and Wherever the facing can be forced partly into vents (see Fig. 3) during the pressure stage a positive anchorage results therefrom. A

A printing plate so produced will take any of the commonly used oil, alcohol, or watersoluble printing inks. When Water-color inks are used, little pressure is needed to transfer the ink from the plate to the paper. Morever, this plate will do very good vvork on poor qualities of paper. Due to the llght Apressure required, the plate is not Worn even after many thousands of impressions have been taken, and.hence does not need to be renewed as often as is nov:r necessary with other kinds of plates.

It will be seen, therefore, that We have provided a new and greatly improved plate for use in printing, particularly with watersoluble inks and also that a very simple, eficient, and economical method Ihas been provided for making this plate. Other methods of applying the rubber to the face otv the plate, such as by spraying, are optional, and as already suggested, the porosity of 'the rubber sheet, instead of vents in the plate, may be taken advantage of to permit escape of the entrapped air. y

While We have shown and described but a single embodiment of our invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement which do not depart from thel spirit of the invention may be made within the scope vof the appended claims. i

We claim: l f

1. A printing plate having relatively high and low portions defining impression characters all joined integrally with vents leading to certain ofthe low portions, and a wa- Y used in printing oil-soluble inks a thin sheet ter receptive facing adhered to the plate at every point over its printing surface and entering the vents therein.

2. The process of making plates for 'use with water-color inks consisting in securing to the printing surface of a plate of the type of water receptive material while held under tension.

3. The process of making plates for use with Water color inks consisting of covering the printing surface of a plate of the t e used in printing oil-soluble inks with a thm surface layer of unvulcanized rubber, resiliently pressing said rubber covering intimately into contact with the printing surfaces of said plate to impose a surface skin thereon, and vulcanizing said surface skin.

4. The process of making plates consisting of covering the printing surface of a plate of the type used in printing oil-soluble inks with a thinsurface of unvulcanized rubber, pressing said rubber covering intimately into contact with the printing surfaces of said plate, relieving the depressed portions of the plate so as to prevent the formation of air bubbles under the sheet of rubber, and vulcanizing said rubber covering.

5. The process of making plates consisting of covering the printing surface of a plate of the type used in printing oil-soluble inks with a thin surface'of unvulcanized rubber, pressing said rubber covering intimately into contact with the printing surfaces of said plate, previously forming holes in the depressed portions of the plate so as to prevent the formation of air bubbles under the sheet of rubber, and vulcanizing said rubber covermg.

6. The process of making plates for use with Water color inks consisting of covering the impression surface of a plate of the type used in printing oil-soluble inks vvithy a thin facing of unvulcanized rubber, and pressing a plurality of sheets of laminated rubber against said rubber facing to force'it intimately around the edges of the printing surface of said plate to conform it intimately to the impression surface of the plate.

7 The process of making plates consisting of covering the impression surface of a plate of the type used in printing oil-soluble lnks Witha thin facing of unvulcanized rubber, pressing a plurality of sheets of rubber against said rubber facing to conform it intimately to the impression surface of said plate, and vulcanizing said rubber covering, said sheets being lubricated relative to each other and to the rubber facing.

8. The process of making plates for use with Water color inks consisting of covering the impression surface of a plate of the type used in printing oil-soluble inks With a thin ally slidable constituents against said rubber facing to force it intimatel around the edges of the printing surfaces ofysa-id plate.

10. The process of applying an elastic facing material to the impression surface of a printing plate which consists in spreading an adhesive over such impression surface, in laying the elastic facing material over the adhesive-treated impression surface, in placing a resilient cushion against the outer surface of the facing material, and in pressing the cushion against the facing material to impose a surface skin at every point over the impression surface of the printing plate.

11. The process of applying an elastic facing material to the impression surface of a printing plate which consists in spreading an adhesive over such impression surface, in laying the elastic facing material over the adhesive-treated impression surface, in placing a resilient cushion against the outer surface of the facing material and in pressing the facing material against the impression surface through the medium of a resilient cushion having elastic laminations freely slidable relative to each other whereby to shift as required in congruity with stretching of the facing material as it conforms to the varying elevations in the impression surface of the printing plate.

12. The process of applying a facing material to the adhesive-treated impression surface of a printing plate which consists in pressing against the facing material a resilient cushion having ay contact face which is slidable relative to the facing material and to the body of the cushion.

13. The process of applying an elastic pervious facing material to the impression surface of a printing plate which consists first in pressing the material into the depressions of the impression surface, in withdrawing the.

pressure to permit escape of the air which is entrapped and compressed between it and the printing plate, and thereafter in again pressing the material this time to the full depth of the de ressions in the impression surface.

14. he method of making printing medium, comprising forming the image to be printed on a hard late, and thereafter securing a thin skin oi) water-receptive material while held under tension upon the surface of the plate bearin the image so that the resulting surface con orms directly to that of the plate.

In testimony whereof, we have hereunto set our hands this 17th day of November, 1928.

. JAMES T. SIMLIS.

GEO. A. SIMMS.

Images