US2292539A - Stencil - Google Patents

Description

Patented Aug. 11, 1942 STENCIL Wallace names Nichols, Port Washington, N. Y., assignor, by memo assignments to Remington Rand Ina, Buffalo, N. 1., a corporation of Delaware No Drawing. Application March 7, 1940,

' Serial No. 322,758

' 3 Claims. (Cl. 41 -38..

My invention in general, relates to improvements in stencil sheet and method of producing the same, of the kind of stencil commonly used for the reproduction of typewritten, manuscript or printed matter; drawings, photographs or the like, comprising a sheet or member of impressible non-fibrous material containing thereon and therein flock (finely powdered or cut cloth, wool,

silk, cotton, cellulose, fibers or rayon or other synthetic filaments); and the use of said stencil sheet in preparing a stencil therefrom.

Heretofore in the typeand stylus-impressible art, it has been customary to employ for a background upon which to spread the type-impressible substance, a sheet of fibrous matter usually a paper variously called Yoshino, Japanese or cobweb paper, and to place thereon a single or multiplicity of coatings, including a cellulose derivative as nitrocellulose, containing in addition,

various fatty, oily, waxy liquids and solids to impart softness, flexibility and water resistance to the composition. The bodies most often used for this purpose are castor, lard, sperm and analogous oils, paraflin oil and solid parafiin hydro carbons, beeswax, carnauba wax,-montan wax and the like, and high boiling aliphatic esters of monocarboxylic high molecular fatty acids, as butyl or amyl stearates.

In complicated mixtures of organic bodies such as the above, decomposition is prone to set in; the castor and other oils rancidify; the oils spew or come to the surface of the stencilsheet upon standing; stearic acid and waxy bodies bloom or form a white eillorescence" on the surface of the stencil sheet; and other disadvantages are apparent. The oils, fats and waxes used are supposed to exert a softening effect upon the cellulose derivative employed, but the free acids generated upon standing have a deleterious effect upon the cellulose ester especially where nitrocellulose is used, the oils decompose, the waxes oxidize and harden, and other changes take place in a stencil sheet of this nature whereby its value for the purpose intended materially diminishes on keeping.

Furthermore, having once used such a stencil sheet of the present art, and having saturated the cellulose fibrous backing with the usual form wipe or brush off the ink with which'the backof sticky, water-absorbing, water-soluble or oily stencil ink, it is difficult, if not well nigh impossible to re-use the same after standing a few days, primarily on account of impregnation of stencil coating by the softening, disintegrating,

viscous stencil ink base, which, whether of aqueous or oily base, is antagonistic to the cellulose derivative used as the basis of the stencil coating.

The above and other inherent disadvantages of the present used type of stencil sheet which depend in a large measure upon liquid oily material to keep the cellulose derivative tractable, and which materially limits the application and diminishes efficiency, is obviated in the present invention, in that no nitrocellulose, cellulose acetate or other cellulose ester, no easier or other oil, no fats or waxes are used, and there is no necessity for the employment of any added softening, extensifying, tempering, setting or similar agent.

My new and improved stencil comprises two dissimilar components, being a foundation sheet of structureless, neutral, highly stable, elastic member, not adversely affected by extremes of normal atmospheric temperatures, and which retains its desirable characteristics for an almost unlimited period of time, incorporated in which is a proportion of flock or relatively short organicfibers. My stencil sheet is highly moisture-proof, vapor-proof, relatively non-porous, non-yellowing, humidity-resisting, nearly transparent, may

be colored by incorporation in the film or flock .able when used in an approved manner for the purposes intended.

It is practically impossible with a stencil I sheet of the present art after having punctured the same with a multiplicity of characters, to re-use the same after having been softened by the saturation of oily ink and the stencil allowed to stand for several days. Attempts to ing is saturated, tend to rupture and distort'the letters, especially those. having a circular cutout portion such as, d,- b, e, 0, p, q and the like, which have already been intumesced and softened by the action or the ink on the oils, fats and waxes constituting the major portion of the stencil coating substances. Distortion and rupture of the fragile central portion of such letters readily takes place, especially when the ink contains hygroscopic substances like glycerin, which often is'the case.

One of the main objects of my invention is to increase the wearability, stability and permanency of a commercial stencil of the type-1mpressible class and having an easily deformable structure, and a surface of character suitable for obtaining a multiple of copies or impressions therefrom of types, written or drawn characters, by means of the utilization of a novel and valuable form of combined fibrous and non-fibrous material to form the stencilizable portion of the stencil sheet, and to obtain a stencil therefrom by means of stylus or impact against the platen of a typewriter in the usual manner, or by interposed between typewriter and stencil sheet a woven material harder than is the stencil sheet substance, and of sufiicient hardness so that im- V pact of type or stylus thereon will produce a multiplicity of separate holes or apertures, through which ink may flow in obtaining 1mpressions from said stencil.

In one preferred embodiment of my invention for producing an improved stencil backing, and an improved stencil therefrom suitable for stencilizing, I take a sheet of rubber halide or rubber hydrohalide (except the fluoride), with or without the addition thereto of suitable plasticizers, preferably in the softened or highly plasticized condition and distribute over the surface thereof in a uniform manner of a multiplicity of relatively short fibers, afterwards rolling or pressing said fibers into said sheet, with or without the application of heat, afterwards removing excess of fibers and those not firmly imbedded or attached to saidsheet, as by brushing. Or, I may commingle the flock or fibers in suitable proportion with the rubber hydrohalide in the dissolved condition and cast a film from said solution-in the usual manner, after said fiock or filaments have been uniformly distributed as substantially separate entities through out the rubber hydrohalide mass.

Of the rubber halides or hydrohalides, I prefer to use the chloride or hydrochloride as it gives satisfactory results and at the present time is the least expensive of this group of compounds.

In one of my preferred methods, I prepare a solution of the rubber compound in a suitable solvent or solvent combination, of the viscosity, total solids in solution, evaporative solvent speed and other characteristics desired, and intermingle or incorporate with or in the same by any approved method and in a uniform manner a relative minor proportion of fibrous elements or fibers, and in such manner and to. such degree that there will be disseminated in and throughout the structureless mass a multitude of overlapping and interlacing filaments permanently adherent to, entangled in and surrounded by rubber hydrohalide, thus producing, a film typeimpressible and suitable as a' stencil sheet from which to prepare a stencil.

The solution permeates the fibrous cellulosic portion, filling the interstice thereof and anchoring therein. No vegetable, animal or mineral fats, oils or waxes are used, and no setting, or tempering agents added, as is required in the present stencil sheet art. Depending upon the polymer degree of the rubber halide and the presence or absence therein of thermoplasticizing or similar agents, and upon the method of production, and the nature and amount of fibrous material used, there is a normal and considerable variation in tenacity, viscosity and other characteristics of the rubber hydrohalide or halide compound, and the amount of fibrous material deposited upon or in or both, or incorporated with the non-fibrous material.

, The flock or fibrous and/or the non-fibrous portion may be colored in order to obtain a contrast color whereby the cut-out portions are more readily discernible in the finished stencil sheet. The addition of a relatively small amount of mineral filler, as pigment or talc in an impalpable condition or an abrasive as carborundum, emery, kieselguhr or powdered metal imparts an opacity and other valuable characteristics to the stencil sheet thereby diminishing its porosity, which under certain conditions is advantageous. Upon dissipation of volatile solvent from the impregnated sheet, it is then in proper condition for stencilization, or the combined non-fibrous matrix carrying the fibrous portion may be smoothed and polished by running said sheet through rollers, by applying pressure or pressure and heat thereto, or treated in other manner.

In an alternative manner of contacting flock or fibers and rubber substance, I may first form a film of rubber halide or rubber hydrohalide, either of smoothed or roughened surface on one or both sides thereof, said film being but a few ten-thousandths of an inch in thickness, preferably moisten one or both sides of the sheet with a liquid having solvent effect thereon, then attach fibrous particles to said receptive surface in any approved manner, afterwards imbedding or finnly anchoring said fibers in said matrix by subjecting to pressure or combined heat and pressure to produce a unitary-appearing member. Said member may be constituted of a single sheet or film of rubber compound with flock or fibers in, or on both or one side thereof, or flock may be incorporated with rubber hydrohalide in the dissolved condition, and afterwards an additional amount of flock may be impressed Into one or both sides of the rubber hydrohalide film, as by manner above set forth.

The preferred thickness of flock and rubber film or rubber composition formed will depend n a large measure upon its relative plasticity and impressibility, and this in turn is governed by the physical characteristics of the rubber halide or hydrohalide, or rubber hydrochloride used, the nature and amount of the plastifiers used if any are employed and the thickness of the finished film and its relative impressibility. Also as to whether the stencil cutting is to be made in the usual manner with a hard rubber platen as the backing, or a separate sheet as a backing, or whether the type impinges on a woven material interposed between platen and stencil during the stencilization operation. This is readily determined by the degree of type'impressibility under the conditions existing.

With a relatively thin impregnation of fibrous portion with rubber hydrochloride in the dissolved condition, and removal of solvent therefrom a rubber platen of varying degree of hardness may be used. On the other hand, with a thicker film of rubber hydrochloride, or a thinner film carrying a larger proportion of fibrous material or where the rubber hydrohalide film has greater tenacity and a relatively lesser degree of type impressibility better results may be obtainable by the interposition of a relatively cally combined with fibrous particles.

. sheet.

Where such woven material is employed, I have obtained excellent results by the use of a wire mesh cloth, such as a Monel, brass or bronze metal screen, of 100 mesh, or preferably finer mesh. A 200 to 400 mesh metalscreen gives excellent results in this connection under various conditions.

By rubber halide or rubber hydrohalide, itis to be understood this expression includes rubber hydrocarbons and cyclocized rubber in the form of a non-fluorine halogen compound. These bodies combine extreme tenacity and stability, suppleness and impermeability, and admit of a clearly cut edge to the characters, an portant consideration when compared with the yielding fatty, waxy and oily composition of the present stencil sheet coating. This is-especially evident in the cutting of small closed center characters as degree or percentage or writings of chemical formulae (Gas) or in the drawing of fine lines or shading in pictorial work.

Where relatively large numbers of mimeograph copies are desired,- then it is advantageous to employ a thicker sheet of rubber compound physi- In such instances it may be more advantageous to obtain the stencil by impingement of type against metal wire screen interposed between platen and stencil sheet, or by the use of an abnormally hardened rubber composition platen.

Where a comparatively lesser number of stencil impressions is to be made, a relatively thin rubber hydrochloride film carrying interlacin fibers may be indicated for more satisfactory results, in which case the use ,of a woven hard surface between platen and stencil sheet may be dispensed with. For the ordinary class of work, a combined fiber and rubber hydrochloride stencil sheet up to ten one-thousandths of an inch in thickness, or greater in some instances, has been found to give a large number of copies of satisfactory appearance, and to be usable a number of separate times at varying intervals of time.

Where a woven material is inserted between typewriter platen-and stencil sheet, upon contact of type bars with stencil sheet, the metal portion of the individual letters comes in contact,v

or nearly so, with the ridges only of the woven material, and at those points of contact pierces the stencil substance with a series of "poin or "bars," apertures of cut-outs therein ofnonuniform size and shape, but at substahtiallyequal distances, and corresponding to those points or places of contact between type and portions Through these minute orifices or punctures, representing an outline of the'particular letter, ink exudes in reproducing copies made from the stencil sheet, to constitute the individual letter or character.

The number and/or size of these directly with the mesh of the indurated woven material with which the type comes in contact, being of a greater number and closer together, as the mesh of the woven material increases per linear inch.

Due to the natural mobility and fiowability of the usual stencil ink, be it aqueous or oily in character, the ink upon penetrating into and through one of these tiny orifices, by virtue of the pressure behind the same, tends to ooze. or spread out, so that the irregular pin poin originally produced, tend to run togetherv and coalesce on the paper, thereby'forming what ap- Pears as a solid outline of the individual letter.

The portions or points between successive punc- Heretofore in the stencil art, this inner portion was held together, if at all, only by means of the Yoshino interlaced fibers, and these fibers were prone to tear apart and distort by the normal pressure and friction incident to obtaining copies therefrom. In the stencil sheet of this invention, I have the double strengthening of cellulose fibers and rubber hydrochloride substance.

The relative size of the punctures and distance between the same, may be regulated between comparatively wide limits by a selection of the fineness of mesh of the woven material and diameter and gauge of the individual wires if a wire mesh fabric be used, or the denier 0f the individual filaments, if a non-metallic woven material be employed.

When the requisite copies desired have been obtained. from a stencil of the composition set forth in this invention, or its equivalent, the ink on'the obverse side of the stencil sheet may be removed by brushing or wiping, and the stencil sheet stored for re-use ata future time, the

stencil ink having no appreciable deteriorating action upon the stencil composition. due to the insolubility of the rubber hydrohalide and the flock or fibers in the ink components.

Iclaim: Y Y

,1. A typeimpressible stencil consisting of a sheet of rubber chloride impregnated with iiocb 2. A sten'cilizable sheet consisting of rubber hydrochloride having a surface thereof impregnoted with fibers.

3. A stencilizable sheet consist-i118 of rubber hydrochloride having a small amount of filler and impregnated on a surface with flock. 1 WALLACE HUNTER NICHOIB.

holes vary