Patented May 11, 1943 2,318,803 UNITED STATES PATENT OFFICE 2,318,803 MARKING QOMPOSITION Wallace K. Schneider \and George W. Seagren, Pittsburgh, Pa., assignors to Stoner-Mudge, Inc., Pittsburgh, Pa., a corporation of Pennsyl vania No Drawing. Application March 18, 1942, Serial No. 435,132 - 6 Claims. (Cl. 106-49) This invention relates to acomposition for the like, and/or certain metals of which selenium marking metal ingots, castings, rolled sheets and and gold are typical. like metal objects which have to be reheated at The term “flux” is familiar to the ceramic or above 500° F. in the process of fabricating to art, and is used to designate a low-melting glass, finished articles. It relates speci?cally to a usually a complex of lead, boron and silica modi marking composition comprising an opaque pig ?ed in its fusing properties by the proportions ment or mixture of pigments combined with a of these oxides and the addition of other particu fusible inorganic "?ux” to be later described, lar materials in a manner familiar to the ceramic and a cellulose ether binder or vehicle stable at art. ordinary temperatures but volatile at tempera The term "colored frit” refers to a combina tures of 500° F. and up. tion of pigment as de?ned above and ?ux, melted In the manufacture of fabricated metal arti together and thereafter quenched by pouring into cles it is necessary to start with the particular water; the shattered fragments resulting are metal or alloy in ingot or “pig" form, and to then further ground into a ?ne homogeneous work it into the particular condition and shape 15 powder. It is this combination of pigment and that is desired by ?rst reheating the ingot to a ?ux, hereinafter termed for convenience and temperature substantially above that at which clarity, a “colored frit” which is component 1 of the ingot is stored. While ordinary paints or our marking composition. _ stenciling inks serve readily to mark a particular We have speci?ed as component 2 of our mark ingot or incompletely fabricated metal billet, and 20 ing composition, a cellulose ether binder stable thus to enable its ready identi?cation during at ordinary temperatures but volatile at tem storage, such markings are invariably destroyed peratures exceeding 500° F. And by the term during the ?rst reheating operation to which “volatile” we mean that at tempertures exceed the billet or ingot is subjected. Accordingly, ing 500° F. the binder disappears completely with there is di?iculty in identifying particular “heats" 25 out evidence of burning and without the inter and/or special ingots after the reheating opera mediate deposition of carbon or carbonaceous tions are begun. residues. And we ?nd speci?cally suited to our It is an object of our invention to provide a purposes certain cellulose ethers, of which methyl marking or stenciling composition which may be cellulose, ethyl cellulose, and benzyl cellulose are applied to the ingot or other crude casting and typical. which will result in an identifying mark which The binder material which is our component 2 remains intact and legible even during and after is selected from a class of cellulose derivatives reheating operations at temperatures exceeding known as cellulose ethers. These resinous ma terlals are well known, and are derived from 500° F. It is a further object of our invention 35 to provide a pigmented composition capable of the interetheri?cation of cellulose and monohy producing marks on metal objects which will droxy alcohols, of which methyl alcohol, ethyl withstand continued exposure to temperatures alcohol, the propyl alcohols, the butyl alcohols, in excess of 500° F. without losing integrity and the amyl alcohols, the hexyl alcohols, cyclohexyl legibility. 40 alcohol and its alkyl homologs, and benzyl al These objects may be attained, and our in who] together with its alkyl and aryl homologs vention lies, in the use of a marking composi are typical. And we ?nd particularly suited to tion comprising (1) an opaque pigment or mix our purposes those cellulose ethers having at least ture of pigments combined in the manner familiar 1 ether group per anhydro-glucose unit; we to the ceramic art with a fusible inorganc ?ux 45 prefer those ethers having an alkoxy content in or low-melting glass derived by melting to the range of 45-55% of complete etheri?cation of the basic anhydroglucose unit. The term gether certain metallic oxides such as silicon di “alkoxy” will be understood to be inclusive of oxide, boron trioxide, lead oxide, potassium ox both alkyl and arylalkyl ether groups. ide, sodium oxide, and diverse other metallic The preparation of our marking compositions oxides, and thereafter powdering to a colored offers no di?iculties. Thus, we may grind the “frit” or “color”, and (2) a cellulose ether binder colored frit which is our component 1 together which serves as a matrix for the resulting “col with the cellulose ether (component 2) on a roll ored frit.” mill, a pebble mill, a steel ball mill, or any other It will be understood that the term “pigment" 55 milling device. If desired, we may incorporate as hereinafter employed in the speci?cation and variable amounts of a softening agent which may claims will be inclusive of single pigments and be a plasticizer such as butyl stearate, dibutyl of mixtures of pigments; they are usually metal tartrate, diethyl phthalate, dibutyl phthalate, oxides of high melting point, typically iron oxide, methyl cellosolve phthalate, cyclohexyl adipate, cadmium oxide, cobalt oxide, chromium oxide and 60 alkyl sulfonamides, triphenyl phosphate, tricresyl 2 2,318,803 phosphate, linseed oil, soyabean oil, perilla oil for use in marking directly on the desired ingot or other drying or semidrying oils, and chlorin or sheet surface; particularly if the surface be_ ated naphthalenes or bi-phenyl‘s. Alternatively, already hot. Thus, for example, a crayon we may incorporate as a softening agent a high molded from the composition of Example 1 was boiling organic solvent of which isophorone, di used to mark an ingot of aluminum alloy imme pcntene. turpentine. cellosolve acetate, butyl lac diately after the latter's removal from the mold, tate, cyclohexanyl acetate, diacetone alcohol, at which time the surface temperature was ap high-boiling mineral spirits, and other cellulose ' proximately 400° F. The ingot was then allowed ether solvents and swelling agents boiling sub to cool to room temperature and stored. Subse stantially above 275“ F. are typical. 10 quently, the marked ingot was placed in an The resulting granular to rubbery homogene annealing oven and held at a temperature of ous compositions may be hot pressed or pressure 950° F. for 12 hours. Upon removal from the molded or extrusion molded into bars, rods, or oven, the ingot was found to bear its identifying other suitable shapes which can be used directly mark in completely intact and legible form. for marking or writing on the surface of the metal The colored frit had fused to the ingot surface, object as with a pencil or crayon. Alternatively, and the cellulose ether .had, of course been the compositions may be dispersed in organic volatilized away, during the ?rst minutes of solvents, such as mixtures of aliphatic ketones, exposure in the annealing oven. esters and hydrocarbons, and applied as desired by a brush or suitable stenciling, lettering, or 20 Example 4 numbering device. Upon evaporation of the Per cent solvent, there results a permanent mark or iden ‘Ethyl cellulose, medium viscosity 46% tifying symbol in which the colored frit imparts ethoxy content ______6.7 contrasting color and opacity, and the cellulose Colored frit fusing at 800° F ______13.4 ether acts as an adhesive binder. Petroleum hydrocarbon cut boiling between When, thereafter, the so marked ingot or sheet 400-480“ F ______18.1 is brought to a temperature exceeding 500° F., Isophorone ______- 22.1 and which will ordinarily lie in the range of 800 Toluol ______39.7 to 950° F. for aluminum and its alloys, and in the range of 1100 to 1300° F. for ferrous metals, the 100.0 cellulose ether binder volatilizes away, without the intermediate deposition of carbon or carbon The composition of Example 4 serves to illus aceous residues; the colored frit fuses and binds trate the use of our marking composition, dis itself to the heated metal surface, and the result persed in a volatile organic solvent mixture to ing fused-on identifying mark is permanent, furnish a lacquer-like composition capable of tightly adhered and capable of withstanding being applied by brushing-as through a stencil normal handling and abrasion without rubbing card, for example. After evaporation of the sol off or becoming illegible. vents the resulting mark has all of the desirable The following examples will illustrate the characteristics previously described. marking compositions of our invention, it being Now, having described our invention, and hav understood that we are not limited to the specific ing shown the advantages intendent on its use. materials, nor to the proportions therein recited. we claim as our invention: All the percentages are on a weight basis. 1. A marking material adapted to be applied to a metal surface, preheated to a temperature Example 1 of no less than 400° F., capable of being subjected Per cent to thermal treatment not exceeding the melting Ethyl cellulose, medium viscosity, 47.8% point of the metal without loss of legibility, which ethoxy content ______46.4 includes in its composition (1) an inorganic Colored frit fusing at 800° F ______46.4 50 metal oxide pigment combined by fusion with a Mixed petroleum hydrocarbons boiling be lead borosilicate ceramic flux, and (2) a cellulose tween 400 and 500° F ______7.2 ether binder. 2. A marking composition adapted to be ap 100.0 plied to a metallic surface preheated to a tem Example 2 55 perature of no less than 400° F., and thereafter subjected to temperatures exceeding 500° F., Per cent Butyl cellulose, low viscosity, 35% butoxy without loss of 'legibility comprising (1) an inor content ______19.0 ganic metal oxide pigment combined by fusion Colored frit fusing at 550° F ______76.2 with a lead borosilicate ceramic ?ux, and (2) a Dimethyl phthalate ______-_ 4.8 60 cellulose ether binder. 3.A marking composition adapted to be ap 100.0 plied to a metallic surface preheated to a temper Example 3 ature of no less than 400° F., subjected to thermal treatment not exceeding the melting point of the Per cent 65 Benzyl cellulose, high viscosity, 40% benz metal, which includes in its composition (1) a oxy content ______16.7 colored frit made from a lead borosilicate ?ux Colored frit fusing at 1000° F ______66.7 and a metal oxide pigment and (2) a cellulose Tricresyl phosphate ______16.6 ether binder together with a softening agent for 70 the latter, said composition being characterized 100.0 by the fact that at temperatures below 500° F. the cellulose ether acts as an adhesive binder for The above illustrative compositions are gran the colored frit, and at temperatures exceeding ular to rubbery homogeneous mixes suitable for 500° F., but below the melting point of the metal hot pressing or extruding into pencil-like sticks surface. the binder volatilizes and the frit fuses to the said metal surface whereby there results a 6. The composition of claim 1 in which the permanently legible mark. ceramic ?ux is a lead borosilicate, the pigment is 4. The composition of claim 1, in which the a mixture of iron oxide and cobalt oxide, and the cellulose ether binder is ethyl cellulose. cellulose ether binder is medium viscosity ethyl 5. The composition of claim 1, in which the 5 cellulose of 45-55% ethoxy content. cellulose ether binder is ethyl cellulose of 45-55% WALLACE K. SCHNEIDER. ethoxy content. GEORGE W. SEAGREN.