US2317551A

US2317551A - Etching

Info

Publication number: US2317551A
Application number: US400425A
Authority: US
Inventors: John J Ormond
Original assignee: JOSEPH D RAMSEY
Current assignee: JOSEPH D RAMSEY
Priority date: 1941-06-30
Filing date: 1941-06-30
Publication date: 1943-04-27
Anticipated expiration: 1960-04-27

Description

A 27, 1943. J. J. ORMOND ETGHING File d June 50, 1941 ing members.

Patented Apr. 27, 1943 UNITED STATES PATENT OFFICE ETCHING John J. Ormond, Boston, Mass, assignor of twothirds to Joseph 1). Ramsey, Boston, Mass.

7 Claims.

This invention relates to methods of etching and more especially to methods of engraving printing rolls.

A principal object of the invention is to improve methods of etching and to devise a procedure for more uniformly and rapidly carrying out etching operations on a printing roll. An-- other object is to provide a means of varying and otherwise controlling etching operations. The invention also aims to provide a method of etching which is simple, cheap and efficient.

The nature of the invention, and its objects, will be more fully understood from the following description of the drawing and discussion relating thereto.

In the accompanying drawing:

Fig. l is a perspective view illustrating a step in the method of the invention;

Fig, 2 is a perspective View illustrating another step in the method of the invention;

Fig. 3 is a perspective View illustrating still another step in the method referred to;

Fig. 4 is a perspective View of a finished printing member; and

Fig. 5 is a detail fragmentary view in cross section.

Referring more in detail to the drawing, numeral l indicates a roll, as for example a copper roll, of the type employed in making textile print- In accordance with the method of the invention, the roll is selectively covered with resist material 2, arranged to form a bare metal outline 3 of a square design, and additional resist material l in the form of spacedapart lines extending diagonally within the outline 3 to leave bare metal lines 5. The resist material is allowed to dry and in some cases exposed to heat and other agents adapted to increase the resistance of the resist to etching reagents.

The roll is covered with an absorbent blanket member 6, as for example an absorbent cotton, which completely encircles the roll and is preferably coated or sealed at its ends with a sealing material such as beeswax 1.

By some suitable means as spraying, coating or dipping, the blanket 6 is impregnated with an etching reagent such as perchloride of iron. Thereafter a pressure element 8 consisting of an inflatable tubular member is wrapped around the blanket 6 in overlapping relation to exert a pressure on the blanket and force the absorbed etching reagent against the bare metal surface of the roll. The pressure of the strap is varied by inflating the element 8 through the valve 9,

to take a position such as that shown in Fig. 5. The etching reagent is thus held under pressure in contact with the roll surface for a suitable period, then removed, and the resist material washed away, leaving an etched outline l0 and etched ground lines I An important aspect of the invention is the method of using an absorbent blanket member to retain or hold an etching reagent in proximity to the surface of a roll selectively covered with resist material. The absorbent blanket member permits the use of limited amounts of etching reagent and affords a desirable means of controlling the extent or intensity of etching, in a substantially uniform manner, all around the periphery of the roll surface.

The sealing material I at the ends of the blanket serves to hold absorbed etching reagent in the blanket when pressure is exerted thereon, thus preventing the acid reagent from being squeezed out through the ends of the blanket and being lost or causing difficulty in any other way. It is pointed out that by tightly winding the tubular member around the sealing material, and in overlapping relation, a substantial sealing effeet is secured all around the blanket.

Application of etching reagents by methods other than dipping or immersing in a bath, as for example spraying or coating, is also facilitated by the use of the blanket member. The use of an absorbent blanket member tends to hold a reservoir of etching reagent which is comparable to immersing the roll in a bath of etching reagent. However, the disadvantage of undercutting resulting from immersion of a roll in a bath of etching reagent is greatly modified, since the blanket tends to direct the etching reagent directly against the surface area of the roll without allowing the etching reagent to come into contact with the sides of etched away portions to any appreciable extent.

In addition to the cotton cited as a suitable material for constituting an absorbent blanket member, I may desire to employ various other materials such as glass wool, fibrous plastics and others. With any of these blanket materials, it is desirable to employ a sealing material at the ends of the roll to prevent the etching reagent from being lost. Other waxes, in addition to beeswax, may be employed, and other thermoplastic materials such as resins and the like, which are substantially impervious to the action of etching reagents, may be desired to be employed.

Another important feature of the invention is the use of a pressure element, preferably in the form of an inflatable tube, wound in overlapping relation around the blanket member noted, to force the etching reagent against the surface of a roll to be etched, and also to act as a sealing member While exerting such pressure. The pressure member serves as a means of applying pressure uniformly at all points around the periphery of a roll. This pressure quickens the etching action of etching reagents in a manner similar to the increased speed of etching commonly obtained by blast etching. It is pointed out that blast etching cannot be readily carried out at all points around the surface of a roll. The combined action of an absorbent blanket and pressure member provides an intensive etching action which is not readily obtained in other ways and the method of forcing acid through an absorbent blanket also tends to prevent undercutting to a very substantial degree.

The inflatable tube not only affords a means of increasing the pressure obtained by winding a strip around the blanket, but also provides a means of varying pressure as for example by intermittently increasing and decreasing the pressure. This variation in pressure is desirable in some types of etching work and makes available a control not heretofore available in etching procedures.

While I have shown an inflatable tube with means for inflating this member so as to vary the pressure which ma be exerted all around the roll surface, it should be understood that various other types of pressure members may be desired to be employed, as for example a resilient sleeve which maybe supported around th blanket in various Ways, as for example clamping and the like. The method described may also be employed in etching various other materials than metals, as for example glass and and like, and the pressure member may be desired to be protected from the etching reagent by the use of materials which are substantially resistant to such etching reagents. The square outline I0 and ground lines I I are intended to be illustrative of various designs of the type commonly employed in printing textiles, and these designs may occur in repetition throughout the surface of the roll and in juxtaposed relation, in some cases, to provide for multicolor printing.

It will be seen thatthe method of the invention provides a desirable control for carrying out etching operations, makes possible greater uniformity, avoids undercutting, is faster, and more economical.

While I have shown a preferred embodiment of the invention, it should be understood that various changes and modifications may be resorted to, in keeping with the spirit of the invention as outlined by the appended claims.

I claim:

1. An improved method of engraving which comprises selectively applying resist material on a surface to be engraved, mounting an absorbent material over the surface to be engraved and the resist material, introducing an etching reagent into the absorbent material, then superimposing over the absorbent material a pressure element and resiliently urging the pressure element against the absorbent material for the purpose of forcing acid against the surface to be engraved.

2. That improvement in methods of engraving printing rolls which comprises applying resist material in selective amounts on a surface of the roll, then securing an absorbent material around the roll, introducing an etching reagent in the absorbent material, then winding an inflatable tube around the absorbent material, and then inflating the tube to exert pressure against the absorbent material and force the etching reagent against the surface of the printing roll.

3. That improvement in methods of engraving a printing member which comprises applying a resist material in selected areas on a printing member to be etched, securing an absorbent blanket adjacent the surface of the printing member, sealing the ends of the absorbent material with a material which is resistant to the etching reagent, introducing an etching reagent into the blanket member, and then compressing the blanket to force the acid into those surfaces of the printing member which are not covered by the resist material.

4. That improvement in methods of etching which comprises applying an etching reagent to a surface to be etched by inflating a pressure element having an etching reagent disposed between itself and the surface to be etched.

5. That improved method of engraving which comprises applying over a member to be engraved a blanket member, sealing the edges of the blanket member with an agent adapted to resist attack b an etching reagent, incorporating. an etching reagent into the blanket, and then applying pressure simultaneously over the entire surface of the blanket.

6. That improvement in methods of etching rolls which comprises applying a resist material in selective amounts over the roll surface, then wrapping a blanket member around the roll surface, said blanket extending from end to end of the roll, applying a liquid agent adapted to resist etching reagents over the ends of the roll and also over the edges of the blanket, incorporating an etching reagent into the blanket, then superimposing about the blanket a pressure member for the purpose of exerting pressure on the blanket, thereby to facilitate etching of the roll.

7. That improvement in methods of engraving a printing roll which comprises applying a, resist material in selected areas of a printing member to be etched, securing an absorbent blanket adjacent the surface of the printing member, introducing an etching reagent into the blanket member and then applying pressure simultaneously over the entire surface of the blanket to force the etching reagent into contact with those surfaces of the printing member which are not covered by the resist material.

JOHN J. ORMOND.