US2316768A - Method of making screen stencils - Google Patents

Description

Patented Apr. 20, 1943 METHOD OF MAKING SCREEN STENCILS Joseph B. Brennan and Leona Marsh, Euclid, Ohio; said Marsh assignor to said Brennan No Drawing. Application June 20, 1939, Serial No. 280,132

8 Claims.

This invention relates to all-metalscreen stencils and process for the manufacture thereof and is a continuation in part of our copending applications Serial Number 115,208 filed December 10, 1936, and Serial Number 175,240 filed November 15, 1937, and Serial Number 268,570 filed April 18, 1939. v

This invention has for its especial purpose the making of all-metal screen stencils wherein for certain purposes combinations of materials may be varied from those heretofore disclosed in the above mentioned pending applications.

For instance metals which are similarly etchable may by this process be used in both the screen material or filaments and the metal configuration layer or layers. I

In this invention the design is etched on a single or multiple layer of metal or metals or their alloys prior to its joining to or embedding same in the screen or Wires permitting a wider choice of metals from which the configuration may be etched or evolved. I

The preferred method of accomplishing the purposes of this invention is as follows.

A unitary metallic layer or layers of uniform thickness preferably of zinc, aluminum or tin or combinations thereof is caused to adhere to a fiat layer of inert supporting material such as fibre board or metal such as steel by an adhesive such as of for example asphalt-um or wax or rubber, cement or glue.

Thus a layer of aluminum foil may be cemented to a layer of stainless steel by superimposing one layer on the other with a thin layer of adhesive therebetween and applying pressure and heat if necessary or by rolling these together.

When sufficiently set a structure results wherein the layer of aluminum foil and the layer of stainless steel may be handled as a unit and having one side exposed of aluminum and the other of stainless steel. Now it being desired to make the configuration of for instance aluminum, the exposed stainless steel may be coated with a resist as wax and next a design of resist is superimposed on the exposed aluminum side of this structure by methods heretofore disclosed in above mentioned applications or by other well known means.

Next the structure of metallic layers with the design in resist outlined on the aluminum side is immersed in an etching bath which is suitable for etching aluminum and the etching is carried on until the aluminum is eaten through in its design exposed areas after which the structure is removed from the etching bath, rinsed and the design resist may preferably then be cleaned therefrom by solvents selected such so that while they remove the resist design they do not cause the etched out aluminum design to part from its stainless steel mounting support. Thus turpentine can be used to remove a litho-varnish resist layer. f

If preferred a tin coated copper foil may be used and the design etchedinto thetin and then through the copper so that the tin may be used to cause adhesion of both metal design layers to the screen by pressure or heat and pressure subsequentlyj Obviously other multiple layer combinations of metalmay be used and other support or backing materials may be used and a wide range of resists and adhesives may be used.

In any case the first major stage of the process comprises producing a metallic etched design layer on a support layer which may subsequently be removed therefrom and which may be used as a transfer support while juxtaposing or extruding the metallic design into the screen.

The next step in our process, after the metallic design is etched where exposed all the way through is to attach this etched design layer to a'fine mesh screen, or set of parallel wires without essentially disturbing the contours or relationship of parts of the etched design layer.

To do this the resistis preferably removed from the surface of the etched metal design layer after which it is with its support superimposed on a layer of line wire mesh screen or a layer of fine wires and pressure or heat and pressure or welding means applied thereto after which the support layer is removed as by a solvent or otherwise and We have an all metal stencil screen resulting.

For instance if the above described stainless steel layer having the aluminum etched design layer attached thereto is placed in a hydraulic press with the aluminum design next to the fine meshed screen which is of a material harder than aluminum then with sufficient pressure applied the aluminum will embed itself in the fine meshed screen and the stainless steel layer may be removed therefrom by solvent action on the adhesive or otherwise and a screen stencil having an aluminum design embedded therein results.

The embedded design is not distorted appreciably during attachment hence excellent definition is obtainable.

Extreme fineness of detail in etching is obtainable hereby because care need not be given to the etchable characteristics of the screen or Wire itself.

By etching the metallic layers separately side actions due to the metals of which the wires are composed are avoided and the etching time to penetrate a definite depth or thickness is shortcried.

Welding may be used as means of attachment and then a material such as paper is preferred as a support for the metallic layer to be etched since the welding will merely burn and penetrate it and not cause irremovable adhesion as might occur if a metallic support were used which would necessitate preferential chemical solution of said metal support after welding. Soldering or brazing operations may also be emplc'ye'dto secure the design to the screen.

In certain cases it may be desirable to use supports of resins or waxes or Celluloid or rubber but the support should be preferably of'low how or nonfiow characteristics becaus of the necessity of avoiding sidewise distortion of the metallic layer design outlines and parts.

Thin metal foils or layers of .010 or less in thickness are preferably used to form the design contours or areas which are etched and subsequently transferred and attached to the screen.

If a combination of metal layers is used they are preferably etchably different so as to secure fine definition due to the thinness of one layer as disclosed in our application Serial Number 268,570 filed April 18, 1939.

Having thus described our invention what we claim is:

1. A process for the production of wire stencils which includes the steps of applying a thin layer of metal to an imperforate support, superimposing an image thereon of resist, etching the exposed areas of said thin metallic layer without etching the support, securing the etched metallic image so produced to a layer of wires or screen by a metallic bond, and then removing said support to produce an all metal stencil.

2. The method of making all metal screen stencils which includes the steps of mounting a thin sheet of metal on an imperfoiia't'e metallic support, etching a stencil design in the thin'sheet on the support without etching a corresponding design on the support, thereafter uniting said thin sheet bearing said design and while mounted on said support to a layer of wires or metallic screen by at least partially"imbeddin'g s'aid wires or screen in said sheet, and then removing the support from the said sheet.

3. The method of making all-metal screen stencils which includes the steps of applying a thin layer of metal to a support, applying a resist to said layer, dissolving away that part of said layer which is not protected by said resist without dissolving the support and thereby forming a stencil design in the thin layer without forming a corresponding design in the support, thereafter uniting the stencil design so formed and while said design is secured to the support to a layer of wires or a metallic screen by a metallic bond, and then removing the support from the said design to produce an all-metal stencil.

4. The method according to claim 3 wherein the stencil design is united to the wires or screen by welding.

5. The method according to claim 3 wherein the stencil design is united to the wires or screen by soldering. V

6. The method according to claim 3 wherein the stencil design is united to the wires or screen by at least partially imbedding sai-d' wires or screen into the metal making up said design without substantially distorting the design.

'7. The method of making all-metal screen stencils which includes the steps of applying a thin layer of metal to a support composed of paper, etching a stencil design in the thin layer of metal on the support without etching acorresponding design in the support, thereafter uniting said thin layer of metal bearing said design and while mounted on said support to a layer of wires or metallic screen by a, metallic bond and then removing the support.

8. The method of making all-metal screen stencils which includes the steps of applying a thin layer of metal to a support composed of paper, etching a stencil design in the thin layer of metal on the support without etching a corresponding design in the support, thereafter'welding said thin layer of metal bearing said design and while mounted onsa-id paper to a layer of wiresor metallic screen and then removing the support. 7

JOSEPH B. BRENNAN. LEONA MARSH.