US 2410472 A
Description (OCR text may contain errors)
N0 5 1946.- A. J. wARTHA sANDBLAsT sTENcn.
. Filed Jan. 11. 1940 Patented Nov. f5, 1946l 2,410,472 v Y sANDBLAs'r sTENcIL Alfred J. Wartlua St. Paul, Minn., assigner to v Minnesota Mining & Manufacturing Company, St. Paul, Minn., a corporation of Delaware Application January 11, 1940, senat No. 313,370
(el. iig-3c) 23 Claims.
This invention relates in general to sheet materials and more particularly to improvements in such sheeted materials as described in my applications Serial No. 358,443, iiled September 26,
1940, ,and issued to Patent No. 2,251,647 on August 5, 1941, Serial No. 275,595, filed May 25, 1939, and
I Serial No. 275,596, led May 25, 1939, issued to Patent No. 2,251,646 on Augustl 5, 1941, wherein the sheeting is of a nature to be inherently resistant to abrasion, such as it would be subjected to when used as a stencilfor Sandblasting operations, and especially to such materials provided with an adhesive coating which is also characterized by resistance to abrasion and is desirably of a pressure-sensitive nature. -Furthermoreythe adhesive is preferably water-insoluble and normally non-drying. -While the invention is de- 'scribed and claimed with respect to'a sheet material particularly adapted for use in making stencils, it will be understood that the sheeting may be employed for other purposes, andthe invention therefore nds a wide field of utility.
The invention has special utility as stencil material for .limiting the application of fluid in the form of spray or otherwise, and also for limiting the area of a given lsurface exposed to the action of sand particles in a sandblasting operation, it being understood, however, that such limited elds of specific use are cited merely for pur'-` poses of illustration as examples of the utility of the invention in its several phases. A prime requisite of stencil material to be used in inscribing stones, such as granite or marble, Iby Sandblasting. is that it must be sufficiently strong and resilient to resist abrasion by a stream under an air pressure of 100 pounds.` It must be flexible to conform to extremely unevensurfaces on which it may be applied. It must be tough enough to withstand abrasion and yet it must be capable of being readily and accurately cut to form a stencil aperture of an intricate design. It must adhere to the surface to be inscribed flrmlyenough to prevent its displacement during the Sandblasting operation and yet not so strongly as to injure the surface or cause adhesion thereto of particles of the stone surface upon its removal. The prin,-
- cipal object of the invention is to provide a sheet blasting-resistant liner adapted to take pencil and and characterized by a resistant backing coated on one surface with a carbon impressions and .be permanently retained thereon and on its opposite side with an adhesive having blast-resistant properties and which is of -a pressure-sensitive nature adapted to retain the facing the stone surface in composition having the foregoing highly desirable qualities. A further important object' of the invention is the provision of sheet material of the character described which can be produced relatively easily and inexpensively.
One of the principal objects of the present invention is to provide sheet material adapted for making stencils for use in the stone engraving industry Where Sandblasting operations are used,
backing material on the'surface of the stone to vwhich it is applied to a degree suiiicient to resist any action of the sandblast to remove the same, but at the same time permitting the stencil sheet to be readily removed when desired without deany way.
Other objects and advantages of the present invention reside in the provision of a stenciling sheet which possesses .unusual durability under the high pressures employed in pressure blasting; the provision of an improved adhesively coated stencilable sheet in which quick application of the same to a desired surface, including a cold surface, may be made in any-kind of weather; the provision of a stencilable sheet and adhesive therefor in which the adhesive and the sheet are non-hardening and in which the adhesive is pressure-sensitive; the provision of an improved form of stencil sheet which permits, in high-V pressure sandblasting methods, of highly accurate work by the operator and to permit the operator to do what is known as ne edge or shape carving; the provision of an improved form of stencil sheet in which the adhesive employed possesses a high degree of tenacity for the surface to which it is applied, thus preventing the stencil from leaving the stone while blasting and, at
the same time, in which the adhesive will not` oiset onto the softer stones or pull away particles of the stone when itis removed therefrom.
The invention is disclosed in two principal em-` bodiments, each of which is characterized by the provision of several laminations having av backing capable of readily yreceiving and retaining marking, such as are used as transfers in the monument trade or a design drawn with an ordinary lead pencil;. and in'which such a stencil sheet -may be employed as a. substitute for sci-called oil?- set blanksemployed by lithographers. In one embodiment, the layer of highly blast-resistant material is coated on one side with an adhesive adapted to be attached to the stone or other article to be inscribed, and on the other surface an adhesive to which is secured a layerv of treated paper' or cloth which has a back sizing capable of readily receiving and retaining marking. The
' other embodiment is somewhat similar, and one surface of the-highly blast-resistant layer is provided with the back sizing vcapable of receiving tough, exible, blasting and retaining marking and the other surface with an adhesive to which is secured a layer comprising Troya tissue or a thin cellulosiolayer having similar properties coated with an adhesive adapted 4to secure the composite to a stone or other surface to be inscribed. Removable liners of parchmentized paper and starched Holland cloth to protect the adhesive .coating while the sheet is in roll form are disclosed in my cepending applications previously referred to. The presentA invention represents an improvement over theseV constructions in that the diiilculty of removing parchmentized paper liners and Holland cloth liners from the adhesive .is eliminated. The provision of a permanently secured liner permits the usage of a thinner stencilsheet backing than in previous sandblest stencilk sheets known to the art without loss of blast-resistant properties.
The invention wil be readily understood from the following description in conjunction with the accompanying drawing wherein certain preferred embodiments are shown, in` which:
Fig. 1 is a plan view of the stencil sheet material with apertures cut therein to provide a design: Y
Fig. 2, an enlarged sectional view taken along the lines 2-2 of Fig. 1 and showing the improved stencil sheet material provided with apertures secured to a slab; A
Fig`r3, an enlarged sectional view of a modied forni of the stencil sheet secured to a slab;
Fig. 4, an enlarged sectional view of a further modified 'form of the stencil sheetsecured to a slab.
vcompatible with the backing so as to have greatery A satisfactory construction, shown in Figs. 1-3, embodying the foregoing highly desirable results 4 naphthol maybe omitted if desired. but the most satisfactory results have been obtained in following the formula as herein set forth.
Factice is a vulcanized or blown oil which mixes evenly with the rubber to increase the homogeneity ofthe mass and also serves to reduce the nerve of the rubber. 'Ihis latter function is important in that the ordinary characteristics of rubber as to toughness and elasticity are not desirable in this composite sheet as they would cause the sheet to be difficult to cut accurately to the desired design. Vulcanized vegetable oils (factice) have been found to be particularly suitable for this purpose. For example, such vegetable oils as vulcanized linseed oil, tung oil, cottonseed oil, corn oil, and sunflower seed oil have been found to be satisfactory. The reduction of the nerve of the rubber is further accomplished by the intensive milling in the preparation of the composite material as hereafter disclosed. Solros is a heat-treated wood rosin used in this composition as a tempering agent particularly during the milling process.' Other rosins may be employed and mineral oils may be employed, in whole or in part, to replace the vulcanized vegetable oils. Beta naphthol is an antioxidant used to prolong the life of both the rubber and the glue of this composition.. f
The fibrous fillenwhen used, is preferably of a nature which permits of free cutting of the material, as cotton linters, paper fibre, wood nbre,
' grass fibre, or mixtures thereof, and the like.
' thiuramtetrasuliide, selenium, m-dinitrobenzene,
For vulcanizing the compounded sheeting, if desired, such agents as commonly used for that lpurpose may be utilized, viz., for example, sulphur or sulphur-bearing agents as dipentamethyleneand the like, with or without the inclusion of an accelerator, as, for example, diand trlphenyl- 40 guanidine, tetramethylthiuram and piperidine adhesion for the backing than for a surface to which the stencil may be applied. To the oppositesurface of therubber sheet in this embodiment is applied a treated sheeting preferably of cellulosic material having a coating capable of taking pencil and ink impressions by transfer and noli adapted to offset adhesive'thereon when ro ed.
In the other embodiment shown in Fig. 4, likewise of a laminated construction, the coating adapted to receive impressions is applied as a backsizing to the rubber composition sheet.
In all of the embodiments, the rubber com.- pounded-backing sheet isconvenientlymade up from a rubber compound including rubber such as latex crepe, which may be vulcanized, Whiting, bone glue' siftings, Solros, factice and beta lnapl'ithol with or without fibrous material. In
this composition the writing provides a finely divided base material which is bonded together to form a coherent mass by the rubber. v'Other comminuted base materials, such asDixie clay,
. soapstone and the like', may be employed instead of writing, in whole or in part. The bone glue siitings are a convenient form of finely divided glue which serves as a bodying ingredient in addition to the Whiting, 'and also gives firmness togthe 'composite sheet which enhances the ease and accuracy of cutting apertures yin the sheet to form the stencil., TheA ,glue Solrosv and beta derivatives.
While the proportions of these ingredients may be varied within reasonable limits, I have found proportions by weight Iaccording to the following formula to give a desirable Acomposite sheet material:
FORMULA A For my purposes it' is preferred to place the rubber in a mill and then mill it until the massv follows the mill roll and gives the appearance of a smooth film covering the roll This takes approximately ten minutes of milling time.
The bone glue siftings are then added andthe rubber and glue, in substantially equal amounts, milledfor approximately-thirty minutes. From time to time the mass may be treated with steam applied directly thereto, thus moistening the glue content andcausing the same to more rapidly melt into and mixwith the rubber.
, I then mix thoroughly together the factice,
Whiting, lSolros and beta naphthol and when well mixed they are added to the rubber-glue mass.
4.This mass -is then milled under steam application untilthe entire'batch is thoroughly homogenized.
When the composite mass made 'according to the above formula has been thoroughly mixed, it
andere 5, is then sheeted or calendered 'the desired thickness. which, for example, me?
be approximately .035 inch. This sheet isthen tent and obtain a workable sheeting;
with no van'ation in the aging inhibitor. when desired, there may be added ibrous material in.
proportions varying from .5 to 80 parts and/or in either case the compounded material may be vulcanized in a manner well known in the art.
To make a fibrous type sheeting or compounded material of the nature as herein described,
after obtaining a homogenized mass by compounding the material of Formula A, fibrous material in the form of cotton linters; either dry or moistened, for example, is slowly added to the mass, preferably in the proportion of- 1 part iibre to 2 parts compounded mass and milled or mixed until thoroughly incorporated therein, as fully de scribed in my copending application Ser. No. 275,595, led May 25, 1939. This proportion of libre preferably is the maximum desired, and I have found that for some purposes as in blasting glass, where sheetings of .011 inch in thickness may be used, the libre content may be reduced to toform-ash/etof Parts Bone glue siftings 10 to 25 Rubber content 10 to40 Whiting 30 to 'l5 Rosin .45to 1 Factice 2.50 to rubber as contained in the aforementioned formula:
Parts Zinc oxide 5 Stearic acid 3 Sulfur 3 Accelerator "D, P. G. (diphenylguanidine) l mixed by milling with the compound of Formula Afor approximately minutes and sheeted and Vvulcanized at 250 F. for two hours. In addition.
the vulcanized sheet material may be a composition mixed in the following proportionate parts:
Parts Formula A 530 Zinc oxide 25 "D. P. G. accelerator 1 Sulphur 4 which may be mixed by milling for approximately -30 minutes, then sheeting it and vulcanizing it at 250"A F. for approximately six hours. or for longer periods of time at lower temperatures.
As a substitute for the vulcanizing agents expressed above, I may use a sulfur bearing compound, such as Tetrone A (dipentamethylenethiuramtetrasulde), or the like, milled directly into the compounded plastic stock with subsequent sheeting and vulcanizlng at a temperature.
of approximately 250 F. for a period of two fractional parts and satisfactory results obtained.
for approximately 24 hours to impart irmness thereto.
In order to obtain a vulcanized rubber sheetin the compounded material may have vulcanizing agents and accelerators included by mixing them into the mass during its compounding, or the hours.
The antioxidant, vvulcanizing agents and their accelerators as expressed are illustrative examsheeted to .022 inch thickness, more orless, as
After a backing of the above composition has been formed with or without vulcanization and ythe inclusion of fibrous material, the resultant Y sheet, of the-embodiments of Figs.2 and 3, is
provided on one side with a liner adapted to be permanently retained thereon and on the opposheeting may be treated with vulcanizing agents,
as described in my copending application, Ser. No. 275,596, filed May 25, 1939, issued to Patent No. 2,251,646 on August 5, 1941. For example. after cooling, the sheeted material may be treated with site side with an adhesive preferably of a pres-Y sure-sensitive character which requires no actipressions, can be cut readily with a knife'and will prevent oisetting of the tacky adhesive coating on the opposite side of the sheeting'when in contact therewith, when the sheet material is laid out and a coating of sulfur chloride is' brushed or sprayed onto its exposed surface and allowed to stand until vulcanized However, I may immerse or subject both surfaces to the solution to obtain a faster and more thorough vulcanization upon evaporation of the solvent and reaction of the sulfur chloride, with a vulcanizable material contained in the composite sheeting.
Alternatively, when a compoimded backing completely vulcanized is preferred, I incorporate, for example, with the Formula A, following its compounding, stock curing or vulcanizing materials ofthe following character d in proportionate parts by weight based on parts l Oleum spiri is rolled or` stacked.
The liner of the embodiments of Figs. 2 and 3' is a treated cellulosic material which is preferably a porous paper or cloth, as for example, a
long bre rope paper, such as Manning rope stock paper or the like, unified by treatment with a saturating solutionvof the following character expressed in approximately proportionate parts by weight as:
Y 7 A prepared by mixing and churning until the viscosity is approximately between 15-18 secs. at 100 F. The paper or cloth is saturated with this composition in the usual manner of impregnation and, when properly dried, is backsized with a material which takes pencil or ink transfer impressions and is preferably made up as a solution of glue or a cellulose derivative such as ethyl cellulose, cellulose acetate, cellulose xanthate or cellulose nitrate, with or without a suitable plasticizer such as dibutyl phthalate. A suitable formula in proportionateparts byweight is as follows:
. FORMULA C Parts Ethyl cellu1ose .6 Ethyl alcohol 2. Acetone .6
prepared by cold mixing and coated to the treated paper backing by well-known coating methods. To this composition, during mixing, may be addedsweflling agents, as zein or the like, placed in solution wit-h water and ethyl alcohol, to aid in transferring prints. Other backsize coatings adapted to receive transfer impressions of the designs to be blasted are sheliac, casein, vinyl resins, and zein a corn product dissolved in alcohol and water; these coatings are not as desirable as those first mentioned.
After proper drying by evaporation of the solvents, a pressure-sensitive adhesive, as for example of the rubber-resin type of character, as herein described in Formulas D, E, F, with or without Whiting, is coatedonto the face side of the pre-treated paper and set-up by the usual methods known to the practice, whereupon the prepared sheeting is applied by conventional .means to the compounded backing for pennanent the side opposite the liner with a pressure-sen-V sitive adhesive containing ingredients which are similar to those used in the backing. Due in part to this similarity an'd in part to the nature yof the adhesive compound, the bond which results when the adhesive is applied to the backing is of such strength that it is practically impossible to cause subsequent separation by mechanical means. This condition prevents lamination or'separation even under the most adverse treatment. y
An illustrative formula for an adhesive by weight may be:
FORMULA D Pounds Latex crepe rubber 40 Zinc oxide 20 Whiting 20 Solros rosin 26.7 Beta naphthol .4
The process of making the adhesive which I prefer to employ for the purpose of this invention preferably is carried out by running the throughout the latex crepe. I then add the Solros rosin and subject the whole batch to a'thorough mixing. The batch is then removed from the mill with a scraper and may be stored in ,trays with a powdered liner until ready for application to the sheeted backing by heating and caiendering.
In this formula the relatively large ratio of pigments, such as zinc oxide and Whiting, serve to make the adhesive blasting resistant, and the resin ,in this case serves as a tack-producing ingredient to give the adhesive the desired normally tacky character.
A softer pressure-sensitive adhesive, which is applicable to cold surfaces' as cold stone, and to other surfaces, may be employed and is a composition of the following character:
Femmina E Part 1 Pounds Smoked sheets 50 Zinc oxide 25 Pine tar 3 Resin V.5 Beta naphthol .5 Peptizing agent 0.15
prepared by milling the smoked sheets on a standard production mill at the approximate temn perature of F. until smooth and then adding .ly requires a minimum of 30 minutes.
To the composition of Part 1 is further added a plasticizing agent and additional tack-producing resins in the following proportionate parts:
Part 2 Pounds Part l-- 4.35 Plasticizer (stearic acid) .50 Rosin (water white) 1.24 Solros rosin .41
compounded by further milling until the product is uniformly plastic and adhesive whereupon it may be calendered to the yprepared backing or stored, as previously indicated, and later warmed for caiendering.
An adhesive of a vulcanized pressure-sensitive type possessing such characteristics as to render the compounded backing particularly suitable as a pressure-sensitive adhesive sheeting may be, for' example, a composition comprised of the following:
FORMULA F Grams Latex crepe 1000 Zinc oxide 200 Peptizing agent 2 Antioxidant 25 Plasticizer 5 Vulcanizing agent .'lf
prepared by milling the crepe and zinc oxide for approximately 4 minutes at 20 lbs. steam pres-V sure, adding the peptizing agent, such as RPA #2, a commercial mercaptan (naphthyl beta mercaptan), "or-other peptizing agents. such as tion, and it mately 30 minutes. This compounded crepe composition is thenV removed from the milling 20 hours at approximately 250 F. tc 260 F.. at which time the vulcanizing agent, preferably a prepared sulfur-bearing compound as Tetrone A" (dipentamethylenethiuramtetrasuliide) mixed with 500 grams of a filler such as Dixie clay, is added with continued mixing for an additional hour or until such time as is necessary to Vulcanize the adhesive. This vulcanized material is then removed from the mixer-and calendered in the usual manner of calendering onto the stencil sheet backing. The desired.
The adhesives of the foregoing formulae possess great tenacity, and I lnd that, for some purposes, I am able to reduce its tenacity and yet have it retain the desired degree of adhesion to a surface to which it is applied by reducing the adhesive character v thereof. This is accomplished, for example, by increasing the proportion of filler, Whiting or the like.
Referring now more particularly to the draw-l ing, a preferred form of the stencil sheet is illustrated in Figures 1 and 2, wherein the reference character d indicates a backing'sheet which may be formed from a composition of Formula A comprising comminuted base material bonded together by rubber and a rubber modifying agent, or may comprise the composition of Formula A and fibrous material, or a vulcanized rubber compounded backing sheet, as previously fully described. One surface of the backing sheet is provided with an adhesive coating 5 which is of a rubber pressure-sensitive nature and may be made lin accordance with the adhesive formulae herein set forth. To the other surface of the backing sheet is secured a treated paper liner 6 adapted to be permanently retained thereon during the Sandblasting operation due to the interposed adhesive layer 1. The upper exposed surface of the liner is provided with a thin coating 8 adapted to receive markings and transfer designs to facilitate cutting the desired stencil openings and may comprise a coating prepared in accordance with Formula C, previously stated, or
prevent offsetting of the pressure-sensitive adhesive 5 when the stencil sheet material is rolled prior to its application to a surface to be blasted and need not be removed when the stencil is to be applied to a surface, such, for example, as the slab of marble 9, shown in Fig. 2. The design forming apertures I 0 and Il may be cut in the composite stencil sheet either before application to the surface of the slab or after` such applicawill be understood that the design to be cut in the stencil sheet may be applied to the liner coating 8 by pencil, pen, transfer or other instrument prior to or after application of the stencil on the slab.
When the stencil sheet is applied to the surface of a slab 9, the adhesive coating tenaciously adheres to this surface and is adapted to provide dams I2 along the margins oi' the stencil apertures I0 and l I, so that the sandblast strihng rolls and placed -in an `internal mixer, such as a Baker-Perkins Mogul machine, and mixed for filler" may be omitted if the exposed surface of the slab through these openings will cut recesses corresponding in shape to the openings and will not deflect and cut away under the stencil sheet itself.
Due to the resilient nature of the adhesive 5, the backing sheet t and the liner 6, the particles of sand striking the exposed surface coating 8 of the liner 6, and striking the walls of dams l2, are caused to be repelled or deflected without substantially wearing away this surface.
Referring to the embodiment shown in Fig. 3,
this construction is similar to that of Fig. 2 except that the liner i3 is formed of cloth, preferably treated in the manner previously described, instead of paper. The cloth liner is provided With a thin coating 8 adapted to receive markings and transfer designs, and the liner is secured to the backing sheet 4 by an adhesive layer l. The backing sheet i and the adhesive 5 securing the backing to the surface of the slab 9 are preferably formed of the compositions previously described.
By virtue of the permanent liner, I am able to produce a flexible, tough and resilient sandblast stencil sheet that is thinner than those known to the art, and which, because of these properties, adequately-resists penetration and wearing away by reason of the h'igh velocity sand particles used in Sandblasting operations.
Referring to Fig. '4, wherein a sandblast stencil backing sheet having properties similar Ato but of a different laminated construction than the embodiments of Figs. 2 and 3, is shown adhesively aiiixed'to `the surface of a. stone 9. Generally this embodiment comprises a lamination of a thin liner of treated paper `it or like material coated on both surfaces, having some blast resistant properties but insufficient to withstand alone sandblasts employed in the monumental trade, and a. relatively `thicker layer of a composition I5 more resistant to the action of a sandblast than the liner It, said layer l5 being provided on its exposed surface with a back size IB. The liner Ml is preferably a Troya tissue .002 inch thick, although it may comprise a thin layer of Dexter tissue or other paper of suitable strength and thinness-ox fCellophane or cellulose acetate. The Troya tissue liner I@ is ment with a saturating solution to prevent splitting of the liner ld when it is unwound from the roll prior to usage; such solutions are preferably of a rubber resin base which accordance with the following formula:
FORMULA G Latex crepe rubber pounds 250 Zinc oxide do 250 No. 10 rosin do 400 vlBeta naphthol do 2.5
Solvent-such as oleum spirits or heptane gallons-- v82 The latex crepe and zinc oxide are rst milled to uniformly incorporate the zinc oxide in the milled rubber, and the krosin and beta naphthol are then added and the mixture is then completely disolved in the solvent which may be oleum spirits or heptane. The Troya tissue liner is saturated with this composition in the usual manner ofimpregnation.v Other saturating solutions may be employed,.for example, solutions employing reclaimed rubber, gum and a filler which may be Whiting in place of zinc oxide. Satisfactory results have also been obtained by 7 employing a saturating solution such as Formulav first unified by treatmay be prepared in The liner I4 is then coated on bothsurfaces Il, I8 with a normally tacky adhesive which may be of the composition set forth in Formulas D,
E or F or may be prepared according to the following formula:
The process of making lthe Aadhesive which I4 prefer to employ for the purpose of this invention preferably is carried out by running the latex crepe rubber for six or seven minutes in a mixer. The zinc oxide and 40 parts of.. No. 10 rosin, to' gether with the beta naphthol and mixture A,
12 a corn product dissolved in alcohol andwater; these coatings are likewise adapted to receive transfer impressions of the designs to be blasted ibut are not as-desirable as those previously mentioned.
From the foregoing it will be understood that the invention may be produced in several diiferent forms, that is to say, the stencil sheet may be a straight compounded material or a compounded material containing fibre and either prepared in a vulcanized or unvulcanized state, the sheet material having on one side a liner adapted to be permanently retained thereon.
- As an alternative-formula. for the compounded backing, I have had success with a composition wherein the quantity of factice or a similar vul- .canized or oxidized vegetable, mineral or animal are then added and the mixing carried on until the materials are completely dispersed throughout the latex crepe. a mixture of 3 parts of condensation product of acetone and aniline, such as sold vunder the trade name Flectol H, and 5 parts of latexcrepe, which are thoroughly mixed before being added to the pigmented rubber-rosin batch.
The mixture A" comprises The material is then dissolved in a suitable amount of heptane and the 2 parts of the solution of wood rosin are then added and thoroughly mixed in with the other' ingredients.
After the liner I4 has been coated on both of its surfaces with the foregoing adhesive or any of the other previously mentionedl suitable adhesives, its calipreis approximately .005 inch.
The blast-resistant layer i5`may be prepared in accordance with Formula A herein, or it may comprise Formula A and the fibrous material as set forth in my copending application Serial No. 275,595, or it may comprise the vulcanized material as described in my copending application Serial No. 275,596, filed May 25, 1939, issued to Patent No. 2,251,646 on August 5, 1941, as previously set forth This material compounded in sheet form, approximately .035 inch thick, is provided on one surface with a back sizing coating I6 which may consist of a glue coating, preferably comprised of hide glue in a solution containing 1 part glue to 3 parts of water, or theback sizing may be prepared in accordance with Formula C herein or it may be formed of a solution of cellulose acetate or cellulose nitrate with or without a suitable plasticizer such as dibutyl phthalate. y
The layer I5 with the backing sizing I6 is -adhesively combined with the double coated liner Il as the liner I4 emerges from the coating machine, the back sizing I6 remaining on the exposed surface, as shown in Fig. 4. As indicated in the drawing the adhesive coating I8 serves to retainthe composite sheet on the surface to be inscribed without activation of the adhesive. i'
The composite stencil sheet construction shown in Fig. 4 is particularly advantageous when the layer I5 comprises the vvulcanized material previously described, inasmuch as the thin liner I4 tends to inhibit the undesirable stretch of the vulcanized material.
The transfer receptive properties of the back sizing I6, when it comprises a, glue coating, may -be enhanced by wiping the coating with a solution of glycerine and water-Just prior to the transfer. The back sizing I8 may also comprise l -tives, or substituted rubber derivatives, as Duprene," Thiokol and the.l like, reclaimed rubber,
resinous materials as "Vistanex (an isobutylene polymer) and the like.
In the specification and claims where I refer to a blasting resistant material or blasting resistant characteristic or blasting resistance," I mean to includethereby a physical character of resiliency, deforming under the impact of an air blast and material entrained thereby, to reassume its normal contour without experiencing substantialabrasion, drying, or hardening, as distinguished from the objectionable warping, shrinking, expanding, drying, hardening and abrasion of other stenciling or masking materials known to me, which under the action of an air blast and materials entrained thereby, exhibit the objectionable characteristics referred to, after blasting. The term sandblast stencil or sandblast stencil sheet, as used in the specification and claims, denotes sheet material intended for and suitable for use in Sandblasting inscriptions on stone both before and after a stencil aperture has been cut therein. y
From the foregoing description it will be seen that I have provided a laminated sheet compris'- ing a layer of a blasting-resistant material in the nature of a. rubber-#like sheeting including filling agents bonded with a vulcanized or unvulcanized binder which affords easy cutting, a
liner having blast-resistant properties adapted to be' permanentlyretained on one side of thel rubber-like -sheeting and a backsizing capable of taking transfer impressions, the composite being retained on the surface to be inscribed by a pressure-sensitive adhesive which adheres without activation.
What I claim is:
1. As a new article of manufacture, composite sheet material having the properties of flexibility and resistance to impact of abrasive particles, comprising a, rubber compounded blasti-resistant backing, a permanent liner secured to a surface of said backing, a coating adapted Lto receive transfer impressions and prevent the offsetting of adhesive thereon on the exposed surface of said composite material, and an adhesive coating on the other surface of said composite material adapted to retain asid composite sheet material on the article to be inscribed.
2. As a new article of manufacture, laminated sheet material comprising an inherently flexible blast-resistant rubber-compounded sheet backing, a layer of a pressure-sensitive adhesive on one y surface of said laminated sheet, a sheet of treated cellulosic material adhesively secured to the said backing, and a coating of a cellulose derivative adapted .to receive transfer impressions on the other surface of said laminated sheet.
3. As a new article of manufacture, laminated sheet material comprising an inherently exible rubber-compounded blast-resistant. backing, a
coating of a non-drying normally ressure-sensitive adhesive on one surface of said laminated material, a liner of treated paper adhesively sev cured to the other surface of said backing, andv a coating of the group comprising a cellulose derivative, glue, and casein, adapted to receive transfer impressions and prevent the offsetting of adhesive thereon, on the other surface of said laminated material.
' stencil sheet material having the properties of 4; As a new article of manufacture, laminated sheet material comprising an inherently flexible rubber-compounded blast-resistant backing, a coating of a non-drying normally pressure-sensitive adhesive on one surface of said backing, a" liner of treated fabric adhesively secured to the other surface of said backing, and a coating of the group comprising a cellulose derivative, glue, and casein, adapted to receive transfer impressions on the exposed surface of said liner.
5. As a new article of manufacture, laminated sheet material comprising a backing of comminuted base material bonded together by a rubber binder, a coating of a pressure-sensitive adhesive on one surface of said backing, a liner of cellulosic material adhesively secured to the other surfaceof said backing", and a coating of a cellulose derivative adapted to receive transfer impressions on the exposed surface of said liner.
6. As a new article of manufacture, laminated sheet material comprising a backing of comminuted'base material bonded together by a rubber binder 'and an oil modifying agent adapted to reduce the toughness of said rubber, a coating o f a pressure-sensitive adhesive on one surface of said backing, a liner adhesively secured to the other surface of said backing, and a coating of glue adapted to receive transfer impressions on the exposed surface of said liner.
7. As a newarticle of manufacture, laminated sheet material having the properties of exibility and resistance to impact of abrasive particles, comprising a rubber-compounded blast-resistant backing, a pressure-sensitive rubber base adhesiveon one surface of said backing, an adhesive coating on the other surface of said backing adapted to secure thereto a liner of treated cellulosic material adapted to be retained thereon during the Sandblasting operation.
8. As a new article of manufacture, sandblast flexibility and resistance to impact of abrasive particles, comprising a thin liner of treated cellun losic material, coated on both surfaces with a rubber base pressure-sensitive adhesive, and a blast-resistant rubber-compounded sheet backing, said liner being secured thereto by one of said adhesive coatings, the other adhesive coating being adapted to retain said sandblast stencil sheet material on a surface to be sandblasted.
1l. As a new article of manufacture, sandblast stencil sheet material having the properties of flexibility and resistance to impact of abrasive particles, comprising a thin paper liner of cellulosic material impregnated with a primer and coated on both surfaces with a' rubber resin presn sure-sensitive adhesive, and a blast-resistant rubber-compounded sheet backing, said liner being secured thereto by one of said adhesive coatings, the other adhesive coating being adapted to retain said sandblast stencil sheet material on a surface to be sandblasted.
12.- As a new article of manufacture, laminated sheet'material having the properties of flexibility stencil sheet material having theproperties of fiexibility and resistance to impact of abrasive other surface of said backing securing thereto a44 unied liner of cellulosic material adapted to be retained thereon during the Sandblasting operation.
9. As a new article of manufacture, sandblast stencil sheet material in laminated form and having the'properties of flexibility and resistance to the impact ofabrasive particles, comprising a and resistance to impact of abrasive particles, comprising a thin liner of cellulosic materia1 impregnated with a rubber base solution, an adhesive coating on each surface of said liner, a baCking layer of comminuted base'fmaterial bonded to gether by a rubber binder, said liner being retained thereto by one of said adhesive coatings, and a coating of the group ,comprising a cellulosic derivative, glue and casein, adapted to receive transfer impressions on the exposed surface of said backing.
13. As a newl article of manufacture, laminated sheet material having the properties of flexibilityand resistance to impact of abrasive particles, comprising a thin liner of cellulosic material impregnated with a rubber base solution, an adhesive coating on each surface of said liner, a backing layer of comminuted base material bonded together by a rubber binder, said liner being retained thereto by one of said adhesive coatings, and a coating of glue adapted to receive transfer impressions on the exposed surface of said backing.
14. As a new article of manufacture, laminated sheet materia1 having the properties of flexibility` and resistance to impact of abrasive particles, comprising a thin liner of cellulosic materia1 impregnated with a priming solution, an adhesive coating on each surface of said liner, a backing layer of comminuted base material bonded to-v gether by a rubber binder, said liner being retained thereto by one of said adhesive coatings, and a coating of a cellulose derivative adapted to receive transfer impressions on the exposed surface of said backing.
15. As a new article of manufacture, laminated f adapted to receive transfer impressions on the exposed surface of said backing.A v
16. As a new article of manufacture, a stencil designed for use in cutting letters, symbols or designs on a surface by way ofan abrasive blast,
and comprising a compositesheet adapted to be placed against the surface and upon proper shaping thereof to control the blast 4so that it forms or cuts the desired letters, symbols or designs on saidsurface and including anabrasive-resistant outer layer formed of an appreciable amount of vulcanized rubber and an admixture of a material' serving to render said vulcanized rubber tough and substantially inelastic, and an inner layer comprising a permanent liner impregnated with acomposition comprising an appreciable amount of uncured rubber, and an adhesive coating on the exposed face of the inner layer for holding the sheet in adhesively connected relation with said surface. y A
, 17. As a new article ofY manufacture, astencil I designed for use in cutting letters, symbols or designs on a surface by way of an abrasive blast,
and comprising a composite sheet adapted to be placed against the surface and upon proper shap-f ing thereof to control the blast so that it forms or cuts the desired letters, symbols or designs on said surface and consisting of an abrasive-resistant outer layer including a substantial amount of vulcanized rubber and an admixture of a material serving to toughen the rubber and make it substantially inelastic, and an inner layer including a substantial amount of unvulcanized rubber in it and a fibrous sheeted medium for making said unvulcanized rubber substantially inelastic, and an adhesive coating on the exposed face of the inner layer for holding the sheet in adhesively connected relation with said surface.
18. As a new article'of manufacture, a stencil designed for use in cutting letters, symbols or designs on a surface by way of an abrasive blast, and comprising a composite sheet adapted to be placed against the surface and uponproper shapandereV t 16 ing thereof to control the blast so that it forms or cuts the desired letters, symbols or designs on said surface'and including an abrasive-resistant outer layer formed of an appreciable amount of l vulcanized rubber and an admixture ofa material serving, to render said vulcanized rubber tough andsubstantially inelastic, and an inner layer containing uncured rubber, and an adhesive coating on the exposed face of the inner layer for holding the sheet in adhesively connected relation with said surface. A i
2l. As a new article ofrnanufacture, a stencil designed for'use in cutting letters, symbols or designs on a surface by Way of an abrasive blast,
and comprising a composite sheet adapted to be placed against the 'surface and upon proper shaping thereof to control the blast so that it forms or cuts the desired letters, symbols or designs on said surface and comprising an abrasive-resistant outer layer including a substantial amount of vulcanized rubber and an -admixture of a mar terial serving to toughen the rubber and make it substantially inelastic, land an inner layer including unvulcanized rubber in it and a material' for making said innerl layer tough and substantially inelastic,- and an adhesive coating on the exposed face of the inner layer for holding the sheet in adhesively connectedrelation with said Surface.
22. As a new article of manufacture, a, stencil designed for useincutting letters,lsymbols or designs on a surface by way of an abrasive blast, and comprising a composite sheet adapted to be placed against the surface and upon proper shapmg thereof to control the blast so that it forms or cuts the desired letters, symbols or designs on said surface and comprising an abrasive-resistant, substantially inelastic outer layer including an impregnated fibrous sheet and an inner layer including a substantial amount of unvulcanized rubber and an admixture of a toughening agent comprising glue, and an adhesive coating on the exposed face of the inner layer for holding the sheet in adhesively connected relation with said surface.
19. As a new article of manufacture, a sandblast stencil sheet material having the propertiesof flexibilityand resistance to impregnation of abrasive particles, comprising a fibrous sheet per.
manent liner impregnated with a primer and coated on both surfaces with an adhesive, and a blast-resistant rubber-compounded sheet backing, said liner being secured thereto by one of said adhesive coatings, the other adhesive coating being v adapted to retain said sandblast stencil sheet material on a surface to besandblasted.
20. As a new article of manufacture; a. stencil designed. for use in cutting letters, symbols or designs ona surface by way of an abrasive blast, and comprising a composite sheetadapted to be placed against the surface and upon proper shaping thereof to control the blast so that it forms or cuts the desired-letters, symbols or designs on said surface and comprising an abrasive-resistant outer layer embodying an' appreciable amount of vulcanized rubber and an admixture of a niadesigned for use in cutting letters, symbols ordesigns on a surface by way of an abrasive blast,
and comprising a composite sheet adapted to be placed against the surface and upon proper shaping thereof to control the blast so that it forms. or cuts the desired letters, symbols orrdesigns on said surface and comprising a comparatively thin abrasive-resistant outer layer embodyingva substantial amount of vulcanized rubber and an admixture of a material serving to render the vul- Y canized rubber tough and substantially inelastic,
and an inner layer of less thickness than the outer layer and includingunvulcanized rubber l,in it and in addition embodying a material .whereby said inner` layer is'also rendered tough and substantially. inelastic, and an adhesive-coating on the kexposed face of the inner layer for holding the sheet in adhesively connectedrelatlon with said surface.
ALFRIEIDv `J. WARTHA.
Certificate of Correction Patent No. 2,410,472. November 5, 1946.
ALFRED J. WARTHA It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows: Column 3, line 19, for Wil read will; lines 64 and 69, for the Word writing read whit'ing; column 11, line 24, before condensation insert a; column 12, line 74, claim 1, for asid read said; column 13, lines 13 and 14, claim 3, for ressure-sensitive read pressure-sensitive; and that the said Letters Patent should be read With these corrections therein that the same may conform to the record of the case in the Patent Ofce.
Signed and sealed this 30th day of March, A. D. 1948.
THOMAS F. MURPHY,
Assistant Commissioner vof Patents.