US 2022364 A
Description (OCR text may contain errors)
NOV. 26, 1935. J, WALSH r AL 2,022,364
SWITCH COVER PLATE Filed Feb. 26, 1929 Patented Nov." 26, 1 9135 UNITED STATES PATENT OFFICE swrrcn 'covra man Jamar. wahaisoutnomm. m r, Piperoux, Weltwood N. 1., asllanors to Cellulold Corporation, a corporation'of New Jersey Y Application Ritual-26.19; Serial No. mar:
'5 cum- (crew-10a) This invention relates to the production of face tact and its content of fire reducing salts conplates for switches-and thelike, particularly wherein decorativeyeneers are formed to shape j and welded to the switch plate or similar article during the molding operation. Y
Heretofore in the facing or veneering of ob- 'jects with'thermoplastic sheets it has been customary to first form the article, as well as the veneer, to its final shape before the application "of the veneer to the article. This of necessity involves a large number of operations, generally y sirable pattern, design, or'color;
resulting in a product ofhigh cost. Veneering in this manner was, therefore, limited to a narrow field.
Attempts were made to mold the veneer and the article together, but prior-to our invention this has resulted in'a drawing, rupturing, tearing and otherwise ruining of the veneer facing.
An object of our invention is the production of novel veneered face plates for .electric switches and the like. 1
The switch plate herein described-for the purpose of illustrating this invention has a pearly facing and its novelty and particular usefulness lies in its artistic. finish, unalterable form and noninflammable character. It will be obvious, however, that its artistry is not confined to pearl limitation, for. the facing can consist Artistry now enters intoso' many useful appliances, especially those exposed to public view,
that plain metal or other substances of ordinary -character are replaced wherever possible by articles having more pleasing effects. But regard must be had to the special requirements of each case and a switch pfate for example must retain its form under all conditions of exposure and be absolutely safe when in contact with electric sparks or heated surfaces. These demands are met in the switch plate of this invention for it is not only ornamental but durable and free from all fire hazard. It is also superior to a metal plate in its inability to transmit anelectric current in the event of a short circuit thus also acting as an insulation element in electric wiring.
The pearl facing consists of a cellulosic plastic,
' either the inflammable or non-inflammable kind;
In other words, its basecan be of nitrocellulose or acetyl cellulose or in fact any other cellulosie ester or ether capable of forming a thermoplastic composition such as cellulose propionate,'ethyl cellulose, benzyl cellulose, etc. This is because the backing of a non-inflammable material of a nature tending to keep the facing below its .point of ignition, to which eflfect its close conof any detribute. Nevertheless we recommend andprefer' a facing composition made of cellulose acetate or similar organic esters or ethers of cellulose.
It is obvious that the facing material may be .5 I
' of any suitable composition, and may be ofany color s' f tioih. That is, it may be pearly, mottled, striped, plain, or variegated. Any suitable formula maybe used. We find the following very satisfactory for pearly facing material: 10
Coloring matter, may be aded if desired. It is a of course, understood that all examples herein 20 are given merely by way ofillustration.
The back n material also has a base preferably of cellulosic derivative, for instance the ni- ,trate or acetate. The nitrocellulose is quite effective for switch plate purposes inasmuch as its inflammable tendency may be smothered by associating it with a non-inflammable plasticizer, for example an aromatic phosphate, and a plentiful amount of fire reducing salt, of which acheap andeffective representative is'calcium sulphate, 30 may also be mixed therewith.
While any suitable material may be used for the backing, we find the following example very satisfactory for switch plate and other purposes where a substantially non-inflammable backing of Dyroxlin is Another excellent formula employing ,pyroiwlin' is as folows:
Example 3 50 Pyroxylin 10o Camphor or other suitable plasticizer 30 to Zinc oxide or equivalent 5 to Urea or other stabilizer 0.5
As an example including cellulose acetate, we find the following very satisfactory:
Any suitable filling material may be added if desired, such as gypsum in the amounts of, for instance, 50 to 150 parts. Larger amounts of filler may be added, however. Pigments and other coloring matter may be included.
Many other formula: including not only cellulosic plastics, but condensation products, resins,
casein, ,etc., will become apparent to persons skilled in the art.
The particular pearl surfacing material is made by mixing, malaxation, manipulation, coloring, block pressing and sheeting the ingredients in the usual known manner. However any veneering material of suitable base may be employedwithout regard toh'ow it is made. The backing material may be made in the same manner as the surfacing material, or the material for the backing may be stamped, cut, or otherwise formed from a flowed sheet or a sheet taken directly from the rolls, thus eliminating the steps of block pressing and sheeting, or the backing material may be in the form of compressed powder. In many instances the base material and the veneer or veneers maybe composited into sheets, and blanks for molding are then cut therefrom.
What we prefer is stiffness in the backing composition and a susceptibility to hot molding, forv on a hardness due to the absence of or a ve y low proportion of solvent depends the non-warpable character and permanency of form desired, and on comparatively easy molding depends the union of parts into a permanent whole. Hence in many instances, we prefer to use the backing composition in the form of a' blank of compressed powder.
The forming procedure is complete in one operation. A die whose interior corresponds to the exter or of the finished article is employed and therein a union of surface layer or layers and backing is effected. The two halves of the die switch plates are cut -to the general are preferably preheated, and then the backing,
which may be previously heated for preparatory softening, particularly in those cases where the mass is large, and the sheet or sheets of facin are enclosed between them. The facing, however, in those cases, may be used cold, for it gets its molding heat from the die. The backing, of course, may also be used cold, if desired. To facilitate effective welding the back of the facing may be brushed'with bonding agents such as diethyl phthalate, .dibutyl phthalate, etc., or there can be inserted or inclosed between'the backing and fabing for equal effect, a sheet of cellulosie plastic made extra adhesive under heat by a high plasticizer content. The diethyl phthalate, however, is very effective as a cementing aid. It can be replaced by dibutyl phthalate, butthe diethyl is preferred to the dibutyl.
In the formation of'switch plates the blank may be cut from acomposited sheet of base material and veneer, the veneer being composited on either one or both sides of the base sheet. The shape of the die in order to prevent excessive plate and bond the materials together.
flowing oftheheadofeachscrewwithtbematerialueedin Other pigment and coloring matter may be added the base material during the molding operation.
The materials are subjectedto. pressure as soon as possible after the die is arranged as described, and when the union of parts is complete the die is cooled and the finished switch plate re- 5 I moved. v
In the accompanying drawing in which like numerals apply to like parts:
Figure l is a'perspective view of a blank of backing material for a switch plate. Figure 2 is a perspective view of a blank facing material for a switch plate.
Figure 3 is a section through a die showing the materials in place preparatory to molding. Figure 4 is a section through a finished switch 15 plate.
Figure 5 is a perspective view of a finished switch plate.
In the drawing, wherein a particular article is shown merely for the purposes of illustrating the 20.
novel process, the blank of backing material shown at l in Figure 1; is in the case of a switch plate where the facing is brought about the, side edges, preferably slightly less in length and width and slightly greater in thickness than the finished 25 plate. In any event the blank for the backing should preferably conform more or less closely to The backing material is conveniently formed as shown in Figure 1 from material coming directly from the rolls or from material in sheet 4 form after block pressing or from-any other kind of sheet.
The blank forthe facing shown at 2 in Figure 2 in those cases where the edges are also.to be veneered, is preferably somewhat greater in area than the finished plate.
Thematerials are shown assembled for molding in Figure 3. The facing material and the backing material have a bonding agent 3 between same. In th s particular manner of molding, the facing material 2 is supported on the lower matrix! of the die. Upon a lowering of the upper matrix} of the die the materials are forced into the depression 8 of the lower matrix to form the The slight excess of facing material is'trimmed from' the edges of the finished plate in the same operation by the closing of the die.
In figure 4 is shown the manner in which the facing material is formed about and bonded to the backing. r
At 1. in Figure 5 is shown a finished switch plate. The particular plate shown has an opening therethrough shown at 8, having bevelled borders as shown at 9. This opening is, of course, for the operating member of the switch. It is obvious that any other form of opening may be provided in order to adapt the switch plate to any type of switch. At II is shown countersunk holes for attaching screws. The screw holes arepreferably countersunk in order that the faces of the screws may be flush with the face of the plate when the plate is in place. This permits coatingv facing the.plate,-thus adding to the ornamental efi'ect produced.
When compressed powder is used for the backing, same may be formed either into the shape shown in Figure 1 or preferably same may take a form somewhat similar to that of the finished plate shown in Figure 5.
The basic materials described and used and the molding operations set forth are preferred. However, other materials susceptible to molding, for instance condensation products, such as phenolformaldehyde, urea-formaldehyde, glycerolphthalic anhydride, etc., as well as resinous materials, casein, etc. may be substituted and the molding operation varied without departing from the spirit of the invention. Particularly satisfactory results may be obtained by using the condensation products in a pre-formed and partially polymerized state.
Our novel method of forming and bonding two or more parts, one of which is thin, and therefore of low tensile strength, in one operation can obviously be applied to the making of many other objects such as handles of all kinds, gear shift balls, steering wheels, door knobs, door plates, etc. and its applicability to other articles will readily suggest itself to persons skilled in the art to which this novel process appertains.
It is understood that the foregoing detailed description is given merely in the way of illustration and that many variations may be made therein without departing from the spirit of the invention.
1. Molded articles for useas face-plates for electric switches and the like comprising a decorative facing of synthetic thermoplastic cellulose derivative material fused to a backing of a synthetic cellulosic derivative material having 5 non-inflammable characteristics.
2. Molded articles for use as face-plates for electric switches and the like, comprising a backing of synthetic thermoplastic cellulose derivative material filled with fire retarding substances,
said backing being fused to a veneer of decorative material having a cellulose derivative base.
3. Molded articles for use as face-plates for electric switches and the like comprising a veneer of celluloid fused to a backing comprising a synthetic thermoplastic cellulose derivative material substantially'free from volatile liquid solvent.
4. Molded articles for use as face+plates for electric switches and the like, which molded ar- 5. Molded articles for use as face-plates for electric switches and the like, which molded articles are faced with a moldable decorative material having a cellulose acetate base, said decorative material being backed with a substantially 3Q dry non-inflammable cellulose acetate fused to a decorative facing.
JAMES F. WALSH. RENE- P.'PIPEROUX.