Патент USA US2404322код для вставки
2,404,322 Patented July 16, 1946 UNITED STATES2,404,322PATENT i5? ERASER COMPOSI‘ITION" Stanley H. Southard, Richmond Hill, N. Y, as signor to Sun Chemical Corporation, 21. corp ora tion of Delaware No Drawing. Application July 21, 1943, ' Serial No. 495,658 5 Claims. (01. 5149s) 1 This invention relates to erasers, and more par ticularly to erasers for use in removing marks or writings made by pencils, ink, typewriters and the like. .- . One of the principal objects of the present invention is to provide an eraser material pre pared from substances other than rubber or syn thetic rubbers. , I Another object of the present invention is to ally rubbed upon paper they would remove avery;v thin layer of the ?brous sheet of paper along with pencil marks and the like without serious adverse effect upon the paper. " Also erasers for ink vand for typewritten words in which there is generally a deeper penetration have been provided of rub-j her having an abrasive which is coarser than such abrasive as has been incorporated in pencil eras- ‘ ers. I have now found that a synthetic resinous , provide an eraser material comp-rising a synthetic 10 material, having a proper thermoplastic charac teristic, and especially when mixed witha~com~ resin. patible plasticizer can be prepared "which ‘can Another object of the present invention is to be extruded or otherwise formed; and. also can provide an eraser material comprising a synthetic include proper abrasive, the composite material resin of the polyvinyl ester type. I A still further object of the present invention 15 being of such character as 'to provide suitable elasticity and plasticity analogous. to that of‘ the. is to provide an eraser material comprising a rubber erasers heretofore used, and also ofsuch synthetic resin of the polyvinyl acetate type. character that the heat developed by frictionat Another object of the invention is to provide a the localized zone which is being rubbed back and thermoplastic eraser material which may be readily formed, as by extruding, and which is 20 forth over the paper or the like will cause a‘ sur-! face or zone softening of the eraser so thatit sufficiently pliable or elastic to permit of its use will ‘be suiliciently adhesive by itself, or‘ sup without injury to paper or the like and in which plemented by an abrasive, to remove ?bers having the characteristics are so controlled that said marks thereon without objectionable effects upon materialwill have such inherent characteristics the paper, whereby. results are attained substan and also will have its thermoplastic characteris tially like those attained with the use of the tics so controlled that upon use as an‘ eraser the friction will cause limited softening at the local-. former ‘rubber erasers, long-common objects of conimerce.- Also this softening is. the resultf'of? ized- portion effecting the erasing so that rub-. the heat of friction and-is localized in the‘ zone‘ bing occurs the portion sosoftened ‘by friction will remove marks or writingslvmade by pencils, 30; of contact during-rubbing leaving the main body of the eraser with its inherent characteristics'fof: inks, typewriters andthe like, without adverse elasticity and plasticity and adequate to support effect upon the normal characteristics-of the the small softened zone which is effective to ac major portion of the-eraser and upon cessation complish the erasing results desired. The char of the erasing friction the softened local zone will return to its original plastic characteristics 35. acteristics are such that when the rubbing ceases: the thermoplastic material resets to its original to be available for additional‘ erasing‘ operations. characteristics thus permitting additional uses Another object is to provide such an eraser until it is completely worn out as has been true material in which the softening of the friction zone will provide a portion sufficiently adhesive with rubber erasers in the past. ‘ -. and of such strength to adhere to and remove 40. _ In operation I have found that a synthetic res: inous mate-rial of the polyvinyl ester type can be ?bers and marks to be erased, but will be so lim satisfactorily utilized in preparing compositions. ited that the main body of the eraser will retain intended for use as erasers. And by combining its inherent characteristics to have sufficient other suitable materials as hereinafter described strength adequately to support the softened zone, and so that the softened zone will return to its 4.5 the eraser compositions of the present invention will be so constituted that they will not. soften original and homogeneous characteristics with or become sticky at prevailing normal roomtem the main portion of the eraser when the frictional peratures and have the adequate elasticityf'and. ceases. . . plasticity referred to. Also the eraser composi-' Other objects and advantages of the invention will be apparent from the :following description 50 tions described are such that they soften slightly within the friction zone under rubbing which and appended claims. . . attendant upon actual erasing operations, andv As is well known ordinary writing pencils, for. example, have beenprovided with erasers made. yet under such conditions the eraser materials ‘of; the present invention are such that there will bevv of rubber vulcanized to have the proper elas action ticity. and’ body plasticity so that. whenfriction su?icient strength and‘ adhesive characteristics’ 2,404,322 3 In the examples given, dibuty1 phthalate may , so that they can be satisfactorily utilized for re- ‘ satisfactorily be replaced by any softening agent moving marks from surfaces such as paper and the like. In addition I have found that such erasencompositions can satisfactorily be ex-v truded so that it is possible to prepare them in compatible with the synthetic resinous material. For example; a; softening agent, such as phthalic acid'esters, diethyl, diinethyl, and similar esters the desired shape for practical use by simplex mechanical extrusion processes, or by molding. desirable properties outlined above and possessed by the eraser compositions of the pres ent invention make such compositions give quite satisfactory results for use in removing marks, as well as tricresyl phosphate, blown castor oil, ' and other softening agents may satisfactorily be employed. ' tory results. 7 of pencil, ink, typewriter and similarmarks__ from ‘7 various surfaces. ~' ' ' The rosin of the ‘compositions of the types‘ de- " scribed in Examples 1v and 2 gives quite satisfac However, other equivalent resinous materials which are satisfactorily compatible with i the polyvinyl esters of the present invention and / v‘For illustrative purposes, some examples of. > with the softening agent utilized may be incor formulations embodying the present invention 15 porated. satisfactorily, resinous material with a are hereinafter given of compositions which,v in . fairly low melting point, that is one melting below practical commercial utilization were entirely’ ' ' about 125° C. may be employed. satisfactory as eraser material. The present invention'provides an eraser com One composition which produces an entirely‘ . position satisfactory for utilization in removing satisfactory eraser for pencil and ink marks is as 20 pencil, ink and like marks from various surfaces follows: ' such for example as paper and fabrics. And such Example I results are/effected in use by such eraser the com \ .. .. 7 position of which comprise as an essential major Parts by weight ingredient a polyvinyl ester synthetic resinous Polyvinyl acetate_____ _________________ _;.._- _88 Dibutyl phthalate ________________________ __ 6 25 material. Thus by the present invention, there Rosin _____________ __'_ ___________ _; ______ __ 7 is secured such satisfactory product without ne ces'sity i'or'utili'zation therein of any rubber or 6 synthetic rubber material, substances'which or dinarily were heretofore used almost, if not en composition. even without inclusion there tirely, as the essential commercial eraser com in of anabrasive material, such as isv ordinarily employe'diin the. former rubber eraser composi position. And by the practicing of the present invention a material is secured which completely does away with the need for such rubber or rub ber-like agent, and yet in an astonishing manner tions provides an excellent eraser for'ink, pencil, typewriter and other marks. ' And'if thereis added an abrasive material to the" composition described in the above'example, an ‘even greater degree‘ of efiiciencyiin erasing is secured. Further, the composition‘ described in Example 1 can be read ily moldedori extruded into a desired shape, and employment in an eraser intended for removing pencil, ink and like marks as described. An eraser composition of the character 're-' ferred to and embodying this inventionwill have substantially the elasticity and body at normal above composition “ 'this'likewise is' true of the with’added abrasive. adequately satisfactory results are secured in that such compositions are completely satisfactory for , ' “ An illustrative composition containing an abra temperatures as the rubber erasers heretofore ‘ sive material in addition to the composition of long in use, and yet because_ of its thermoplastic character it can be extruded or molded readily 45 into'isuch sizes or shapes as may be desired‘; and 1 the‘ type described in Example 1 ‘is the following: , ' 1 ' ' ‘ Example I II Parts by ‘~ weight 7 , with' abrasive material of the size requisite for ‘ satisfactory erasing operations for the par? I Polyvinyl acetaterwunui; ___________ ..p ‘ Dibutylphthalate _____ __‘_ .... __'__'_'__'___~__ Rosin ..;..'..___'__..___._...__;_.._._.._.;;__.__..;...__.; , 17.6 ticular kind of paper and marks ‘or. writing or '12 printing thereon. This permits a ready forma 1.2 ‘ tion of individual erasers of various sizes and 80.0 shapes, while the thermoplastic conditions are such that when not subjected to heat substanl 100.0 , employed for such material may be used, as for tially outside the range of normal room tem peratures the eraser material will have the elasticity and body of the rubber erasers, as de = example powdered silica, emery, silicon carbide scribed; and will have the additional character ‘ Abrasive and‘colorin‘g material _________ _~__ V ' As abrasivematerial, any of those generally istic that if softened as a result of heat imparted by the friction of an erasing action, or from any other source in connection'with its manufacture known as.“carborundum” and others of similar ‘ abrasive characteristics. The .eraser compositions of the above types de : scribed can satisfactorily be prepared by admix ing the synthetic resinous ' material, dibutyl phthalate and rosin and heating the mixture until 3 it is in a melted condition. The material then may satisfactorily‘ be stirred until homogeneous. If desired the, abrasive material and coloring agent may'then be added and mixing continued , until thelatter'materials are completely dispersed, ‘ and successful operations in practice have been ‘ effected by utilizingr for the mixing operation me 1 chanical equipment such as a ball mill or banbury 3 mill. 'When'the material has been mixed, as for ‘ example above described, they may then be 60 and use, it will reset to the desired elasticity and body when the heating effect is no longer pres-v ent. While the products herein de?ned and the methods of producing the same constitute pre; ferred embodiments of the invention, it is to be understood that the invention is not limited to’ these precise products and methods, and that changes may be made therein without departing from the scope of the invention which is de ?ned in the appended claims. What is claimed is: 1. An eraser composition'of thecharacter de-' scribed, comprising approximately '80 parts by formed'toithe desired shape, and such may satis weight of‘ abrasive and coloring, material, 17.6 ‘ factorily be accomplished by molding in a ‘press parts by weight of polyvinyl acetate, 1.2partsv by weight of dibutyl phthalate and 1.2 parts by ‘ or by extrusion processes. ' 2,404,322 5 weight of rosin, which composition at normal room temperatures has substantially the body characteristics of the rubber erasing material but will temporarily soften in a localized zone of friction in erasing while maintaining the. normal characteristics of the main body of the material. ‘ 2. An eraser composition of the character de scribed, comp'rising approximately 88 parts by weight of polyvinyl acetate, 6 parts by weight of dibutyl phthalate and 6 parts by weight of resin, said admixtured composition at normal temperatures having substantially the same zone which is localized as to depth while main taining said normal body consistency, solidity, elasticity and ?exibility of the main body por tion of the eraser outside said localized friction softened zone, said softened zone being changed by the friction heat to be so tacky and adhesive as to adhere to and remove writings and mark ings from the paper without more adverse effect thereon than voccurs with use of the rubber erasers formerly used which softened zone resets ( to its normal thermoplastic condition ‘at room . temperatures after an erasing operation. 3. An eraser composition as defined in claim 1 in 4. 15 1 in tofore generally used but having the character 5. istic of temporary softening under the heat gen 1 in erated by friction in an erasing operation upon elasticity, ?exibility, body consistency and re sistance to deformation as rubber erasers here paper and the like at temperatures substantially above room temperatures to provide‘ a softened 20 which the abrasive is silica. An eraser composition as de?ned in claim which the abrasive is emery. An eraser composition as de?ned in claim which the abrasive is silicon carbide. STANLEY H. SOUTHARD.