US 3104915 A
Abstract available in
Claims available in
Description (OCR text may contain errors)
Sept 24, 1953 M. J. PERKovxcH ETAL 3,14,E5
scoURING PADS Filed April as;v 1960 FIG.
INVENTORS MARK J. PERKOVICH CHARLES R.WARD
United States PatentV O ce 3, l 04,9 l Patented Sept. 24, 1963 Marit J. Perlrovich, Chicago, and Charles R. Wardvvell and Edgar H. Wolfe, htinnetira, ill., assignors, by direct and mesme assignments, to Generai Foods Qorporation,
White Plains, NX., a corporation of Delaware Filed Apr. 28, wat), Ser. No. 25,3?2 7 Claims. (Cl. 3mi-21;)
This invention relates to a novel scouring pad backing and the method of manufacturing a pad therewith. More particularly, the invention is concerned with the manufacture of cleansing `or scouring devices employing metal wool filaments, such as steel wool, which may have incorporated therein soap or a like saponaceous composition.
Metal wool, for example so-called steel wool, has gained wide acceptance for household scouring of such articles as pots and pans. Securing and polishing pads made of steel Wool, which have been matted or felted together into a mass of intertwined or interwoven elongated filaments, lare marketed in oval and rectangular shapes. Such household cleansing articles must be gripped by the housewife for the proper scouring or polishing effect. Unfortunately, there is a tendency -for the metal Wool to break or splinter which can result in the unpleasantness of slivers entering the skin ofthe user.
'lt would be desirable to provide a suitable backing on one side of the scouring pad so that the pad can be easily gripped and manipulated in the scouring and polishing of .pots and pans. Such a gripipable element would preferably comprise a sheet of paper or other sheet material having a handle formed therein and which is bonded to the metal wool pad. A paper backing sheet would be most desirable for this purpose in view of its cheapness and its ability to Kbe printed with attractive patterns offering appeal to the user. However, in bond- -ing such a paper backing to a metal wool pad, difficulties `are encountered, particularly in high speed production.
To explain, for the steel wool article to be capable of repeated use with the backing element or handle structure, it is important that this latter element be substantially permanently bonded with respect to the body of metal wool during its period of use. To eect this bonding a considerable thickness of adhesive composition is required in order that the metal filaments of the wool will be firmly anchored in the adhesive composition and thereby locked to the backing element and to each other. However, after 'applying an adhesive layer of suitable thickness to a paper backing material, the ibacking sheet tends to curl due to the hygroscopicity of the rpaper. Such `curling creates manufacturing problems. In the operation lof placing the paper backing in place, either by mechanical means or by hand, the paper backing should be 'of adequate flatness for control of placement yon the body of metal wool. Since the backing anus-t usually be bonded to the metal wool body by the application of pressure as Well as heat, an uncurled substantially fiat paper backing avoids the non-uniform registry which could arise in attempting to flat-ten a curled 'backing into place onto the metal wool body, particularly in the case of oval, round or rectangular articles having sloping more or less uneven surfaces. Such curling may be reduced to some degree -by laminating the required thickness of adhesive composition to -a backing material rather than extrusion coating it. But such lamination is relatively expensive and does not vassure complete freedom from a curling problem.
A need exists, therefor, for uniformly backed metal Wool `bodies such as scouring pads which are relatively simple and inexpensive to manufacture and which are ycharacterized by a substantially permanent anchoring of the metal wool filaments to the backing.
A method meeting the foregoing need forms the subject matter -of the present invention. The article or pad made by said method comprises a body of matted interwoven elongated metal wool filaments and a backing combined with an initially free plastic film or ply of high tensile strength and dimensional stability at temperatures below 140 F.; the word free describes a film which is substantially unbonded or not Iadhered to the backing prior to activation through heat or otherwise and hence does not contribute to curling; prior to activation the film is, however, located intermediate the backing and the surface of the metal wool body to be contacted, such location preferably being effected by mounting the free film at one or `more spaced points on the backing `as hereinafter described. The yfree film preferably has a thickness substantially equal to or 'greater than .the largest cross-sectional dimension of the metal filaments and when activated is capable of receiving filament loops therein to the extent that f1-substantial Iplurality of loops of each of said filaments may have the composition of the film fused around adjoining filament loops. Thus, the film of plastic is of such thickness that when the plastic is activated it will melt and flow around the filaments. As `a result the film and filaments are integrally interlocked to the extent that such interlocked filaments will be unwoven `from the metal wool body should the backing film be pulled away therefrom and will in large measure remain anchored to the backing. The character of anchoring can be described as one wherein a substantial plu` rality of the dla-ments at thesurface of the body of matted metal wool penetrate the plastic film, emerge therefrom and reenter the film, .thus locking the successive loops of the filaments whereby the body of interwoven matted metal wool retains its aggregated form or shape. To eect this structure the plastic of which l `the film is composed should be of high tensile strength as well as dimensional stability at least at temperatures below F.; that is, at those tempera-tures normally encountered in the household. At such household temperatures the plastic film should `also remain relatively inert to the action of alkalis, hot water and soaps and should be non-toxic, odorless an-d of such flexibility that, `at the thickness required for proper interlocking of filament loops, the film alone or in combination with a backing sheet of paper, foil, `woven fabrics or the like will be fiexible in use.
The mass of metal wool is preferably composed of elongated filaments of steel, Vwhich filaments are intertwined or interwoven more or less randomly with respect to one another.v The metal wool preferably also has incorporated therein some form of soap or saponaceous composition which serves as a lubricant as well as a detergent effecting appropriate scouring and polishing of pots and pans and similar articles. ln `accord with present `commercial practices, the metal wool mass can be assembled into a suitable pad having au oval or rectangular outline and can be of a compressible, springy nature such that it 'will yield upon the application of pressure when the `backing film is being interlocked with respect to the metal wool filaments. The surface of the pad will preferably be fiat on that side of the pad which is to receive the backing film but may be rounded or sloping, particularly near the marginal edges of the pad.
The film may be of any suitable activatable plastic which lends itself to liquefaction through the action of heat or a solvent serving t0 melt the plastic so that it will receive the filament loops within the plastic film and then solidify to ins-ure interlocking. Although well-known adhesive resins can be activated by use of such solvents Vquantities of plastic as hot acetone and methyl ethyl ketone, such adhesive resins and the solvents therefor are less preferred since their use introduces problems of solvent recovery and .safety control. lIt is preferred toV employthe heat activ-ated adhesives whereby heat may be `applied to the free film, preferably through the backing; upon melting the composition forming the free iilm it will rapidly transfer its heat to the metal filaments, effecting a drop in temperature of the plastic after it is momentarily liquefied and migrated around successive loops of the substantial plurality of interwoven metal filaments. Such compositions as the polymerized oleiins, e.g., polyethylene, are preferably employed. Other suitable fil-m compositions include, for example, microcrystalline waxes -with added polyethylene, polyisobutylene with added paraffin; vinyl acetate; polyamides, butyl rubber emulsions; and like moisture proof adhesive resins.
The film is preferably integrated with sheet material having properties usually found in fibrous cellulosic material yor paper, i.e., flexibility and tendency t absorb resins applied thereto. Although paper in the common or usual sense means a material made from such sources as wood, rag, or bagasse (sugar cane), a broader interpretation of the term paper is intended herein, the term being understood to include such kindred materials as artificial and natural textile :bers which are matted and woven. Also included in the term paper are composite structures made by laminating such paper or paper-like compositions to other sheets such as plastic films, metal foil and the like which may be relied upon to offer an attractive appearance either through an applied design or the appearance 'of the material itself. As a rule, the paper backing sheet for use in combination with .the backing film will be one capable of being printed and will range in weight from 8-90 lbs., preferably about 45 lbs. (basis 24 X 36-5G0=3,000 sq. ft); various kinds of paper that can be used are: papers made from `chemical pulps including sulphate papers, sulphite paper, sulphate-sulphite combination papers, soda pulp papers, these various papers being either uncoated or coated on one or both sides with Va coating comprising clay, titanium dioxide, and binder; chemical pulp or chemical pulp and groundwood combinations, coated or uncoated, which have been calendered or supercalendered such as publishing papers, glassine, supercalendered sulphite papers, machine nish sul-phite-sulphate papers, and machine finish and machine glazed sulphite-sulphate papers, and other materials such as cellulosic iilrns including cellophane and cellulose `acetate, -foil and the like. Preferably the paper backing is embossed so 'as to provide a roughened surface which will facilitate gripping of the paper-backed article. The paper backing also has an outline substantially coextensive with the free plastic lm and the mass of metal wool, and as indicated, this outline may be oval, rectangular, round, or some other suitable shape. v
ln accordance with a` preferred practice of this invention an uncoated sheet of paper is laminated to a body of matted metal wool filaments through the intermediation of an interposed ply of heat activatable thermoplastic adhesive. In the resulting structure, such ply, upon liquerfaction and migration, combines with the paper to form the backing for the structure. Preferably, the interposed ply of plastic is suitably anchored on part of its surface to the backing paper, as -will be explained in detail hereinafter, to insure proper registry of the backing paper to the body of metal wool and the interposed ply. When the paper backing sheet, the metal wool laments and said ply are in position opposite one another, pressure and heat are employed to activate the plastic ply in order that successive loops of each of a plurality of metal filaments Will have fused plastic therearound. The resulting structure, throughout its formation, is characterized by uniformity of placement of the backing due to the freedom from curling of the backing sheet. Furtherpapers made from r more, for a given `weight of plastic, an improved bond is lobtained with the metal filaments.
In a second form of the invention a very thin precoated sheet of paper is laminated to a body of matted metal wool filaments through the intermediation of an interposed free ply of heat activatable thermoplastic adhesive.
'l` he preferred embodiment o-f the invention is shown in FIGS. l through 4, which illustrate the principle of a handle structure incorporated as part of the backing. The second embodiment is shown in lFiG. 5.
HG. l is a side elevation of a paper-backed scouring pad; FlG. 2 is a top plan View of the scouring pad in FG. l; FIG. 3 is a side elevation of the pad in FIGS. l and 2 .taken in section alongV line 3-3 in FIG. 2; FlG. 4 is an enlarged sectional view showing the relationship of ythe paper backing and the free plastic ply mounted thereyon; FG. 5 is a partial View, similar to FlG. 4, but showing a modification.
As seen in FlGS. l-4, the free plastic ply itl is mounted on the backing paper i2 so as to insure complete registry of said ply between the paper `backing and the metal wool i3 when the elements are brought face-to-face and bonded. Such mounting may be effected by spotwelding the plastic ply at spaced points on the surface of the backing sheet but, preferably, ply it? is integrated with part of -a handle 14 of the type shown in the drawings such that ply it? serves the dual function of joining the pair of upwardly extending folded backing paper portions i6 and i8 which Vare juxtaposed and adhered together through the intermediation or" the adjoining and folded portions 2i) and ZZ of the ply it?. However, the present invention is not to be restricted to such details, although they are preferred, and instead :any suitable means for mounting the free plastic ply lil with respect to the paper backing l2 can be employed, in all of which instances plastic ply it] is unbonded with respect to paper backing l2 and metal wool mass i3 on a majority of its surface. v
Flap portions Sil and 32 of the paper backing l2 do not curl, and so `meet evenly with flap portions 34 and 36 of plastic ply lo. To receive flap portions 34 and 36 evenly, the matted metal Wool pad i3 is flattened on its upper face l5 in order to assure complete anchorage of the ply di? along the 4faces of iiap portions 34 and 36.
In production, la plurality of the composite backings of FiG. 4 in a magazine with suitable feed means is serially introduced onto a succession of matted metal wool pads, means being employed to positively pass each of the metal wool pads at a .uniform rate past the magazine feed and assure proper registry of the plastic ply with the flattened upper face of the pad. immediately after such placement the backing `and the pad are constrained to pass between travelling endless belts, rotating rollers or other suitable pressure applying means engaging the backing and the pad respectively lfor Vdelivery past an activating station. in one form, this station may comprise heating means in the form of an electric resistance element or the like contacting the backing either directly or transferring heat thereto indirectly through the means used to maintain the backing and the pad under pressure. The heat transferred to the backing Ishould be below that temperature Whereat the paper backing 12 will burn or char but should produce a suiiiciently elevated temperature to activate the intermediate ply lil so that it melts, pressure being maintained for a suiiicient period of time during the molten state of such plastic to assure that a plurality of the metal wool filaments on the upper face i5 of the pad are immersed in the molten plastic `so that successive loops of such filaments ,are interlocked by being at least partially surrounded by the plastic of intermedii ate ply lil. As indicated, heat may be applied to either or both sides of the backing-pad combination, but it has beenfound preferable to apply heat through the backing only whereby the relatively cool laments of metal wool pad will more rapidly permit transfer of heat thereto from the molten plastic plies to effect rapid solidification. To assist in resolidification of the thermoplastic, cooling means may be employed after suitable bond has been effected between the filament loops and the backing, which cooling means are employed while the backing and the metal wool pad are maintained under pressure.
It has been found that lthe plastic material of ply 19, when rendered molten, tends to flow onto the metal filaments in a satisfactory manner and to interlock well with the filaments, producing a very firm bond.
The embodiment of FIG. 5 is like that of' FIG. 4 except 4th-at a precoating 28 is present on the :backing paper 12. Thus, the FIG. 5 structure comprises the precoated paper backing 12', a substantially free floating plastic ply or film and a handle 14', the latter being formed by the folded portions 16 and 18 of paper 12', by the folded portions 24 and 25 of precoating 23, and by folded portions 20 and 22 of the ply 10. The metal Wool pad may 'be attached to the structure of FIG. 5 substantially in the manner and by the means described above, it having been found that the ply 10 can be bonded to the paper 12 through the precoating without the incidence of curling. The thickness of the ply 10 may be up to 6 mils, more or less.
The term precoated refers to the operation of applying a thin coating of activatable thermoplastic adhesive composition to the paper backing material either by lamination or extrusion coating to provide la bond between the paper fibers and the intermediate ply of plastic or adhesive resin. In the structure eventually produced by use of a precoated paper, the composition of the precoating and the intermediate ply, upon liquefaction and migration or intermingling, form the backing film of the structure. Preferably, as in `the case of FIGS. l-4, the interposed ply of plastic is suitably anchored on part of its surface to the precoated :backing paper to insure proper registry of the "backing paper to the body of metal wool `and the plastic ply. When the paper backing sheet, the metal wool filaments and the intermediate ply of thermoplastic .adhesive composition yare in position opposite one another, pressure and heat are employed to activate the composition of the precoating and the plastic ply in order that successive loops of each of a plurality of metal filaments will have fused plastic the-rearound.
The material used to precoat the paper 'backing sheet may be any suitable heat activatable thermoplastic composition and preferably will be of the same composition as the intermediate free ply used to yadhere the precoated paper backing to the mass of matted metal wool. Such compositions `as those listed .hereinabove identifying the free film may be employed. The material used to precoat the paper backing will generally be applied in a thickness yless than that of the intermediate ply of plastic adhesive and, as indicated, may be-applied either by extrusion coating or by lamination. The precoating composition will have a thickness which does not occasion curling of the paper backing but will be sufficient to provide suitable bond between the paper fibers and the plastic ply and the metal Wool. In general, it has been observed that a thickness -in the range of l to 4 mils will offer a suitable extent of continuous bonding 'between the paper and lthe plastic ply without introducing curling difficulties, although it has been found that la thickness on the order of 2 mils is preferred.
The material of the intermediate bonding ply of thermoplastic, as indicated, is preferably of the same composition as that of the precoating. For example, polyethylene will be employed as the intermediate ply when the precoating material is composed of polyethylene. Usually, the thickness of this intermediate ply of plastic will be greater than the thickness of the coating applied to the paper and should be in excess of that required to offer suitable anchorage to the metal filaments embedded in the plastic upon its activation or conversion into a plastic iiowable condition. The maximum thickness of the intermediate ply of plastic will be dependent to some extent upon the flexibility of the plastic ply which is preferably bent to form part of a handle structure integral with the paper backing. Usually a thickness less than about 6 mils in the case of polyethylene will offer the satisfactory reservoir for anchorage of the metal filaments and for bonding with the activated precoating.
By virtue of the thinness specified for the precoating 23, at portions 30' and 32 of the paper backing 12 do not curl, and so meet evenly with fiap portions 34 and 36 of plastic ply lil.
While the present invention has been described with particular reference to specific examples, it is not to be limited thereby, but reference is to be had to the appended claims for a definitionI of its scope.
What is claimed is:
l. A paper backing adapted to be afiixed to an element, comprising a sheet of paper, and a free film of heat activatable thermoplastic adhesive anchored on only a part of its surface to a surface of ysaid paper sheet and having an outline when opposite said sheet substantially coexten-sive therewith, a portion of said film being folded into face-to-face abutting relation with an adjoining portion thereof, a portion of said sheet being folded into face-to-face abutting relation with an adjoining portion thereof through the intermediation of said folded film portions to provide a grippable handle on said backing, said film being anchored to said sheet only at said gnippable handle.
2. A paper backing adapted to be amxed to an element by means of heat, comprising a precoated sheet of paper, and a ply of heat activatable thermoplastic adhesive anchored on only a part of its surface to the precoated surface of said sheet and having an outline when opposite said sheet substantially coextensive therewith, a portion of said ply being folded into face-to-face abutting relation with an adjoining portion thereof, a portion of said paper sheet being folded into face-to-face abutting relation with an adjoining portion thereof through intermediation `of said folded ply portions to provide a grippable handle on said backing, said ply being anchored to said sheet only at said grippable handle.
3. A process of forming a scouring pad having a backing sheet adhered thereto, comprising providing a exible backing sheet, providing a film of heat activatable thermoplastic adhesive having an outline when opposite said backing sheet substantially coextensive therewith, anchoring said film to said backing ysheet only along parts of a surface of said backing sheet, positioning said film opposite said backing sheet, disposing a body of matted, inter- Woven, elongated, metal wool filaments against 'said film, applying heat to said film to activate said filmv and unite it with said body and said backing sheet, and withdrawing the heat.
4. A process of forming a scouring pad having a backing sheet adhered thereto, comprising providing a flexible backing sheet, providing a film of heat activatable thermoplastic adhesive having an outline when opposite said backing sheet substantially coextensive therewith, anchoring said film to said backing sheet only along parts of a surface 'of said backing sheet, positioning said film opposite said backing sheet, disposing a body of matted, interwoven, elongated, metal wool filaments against said film, simultaneously forcing said backing sheet and said body together and applying heat to said film to activate said film and unite it With said body and said backing sheet, and withdrawing the force and heat. Y
5. A process of forming a scouring pad having a backing sheet adhered thereto, comprising providing a flexible backing sheet, providing a film of heat activatable thermoplastic adhesive having an `outline when opposite said backing sheet substantially coextensive therewith, positioning said film opposite said backing sheet, anchoring said film to said backing sheet only at central portions of said backing sheet and said film, disposing a body of matted, interwoven, elongated, metal wool filaments against said film, applying heat to said lm to activate said film and unite it with said body and said backing sheet, and withdrawing the heat.
6. A process of forming a scouring pad having a backing sheet adhered thereto, comprising providing a flexible backing sheet, providing a film of heat activatable thermoplastic adhesive having an outline when opposite said backing sheet substantially coextensive therewith, positoning said ilm opposite said backing sheet, spot-welding said film to said backing sheet only at :spaced portions of a surface of said backing sheet, disposing a body of matted, interwoven, elongated, metal wool filaments against said film, applying heat to said film to activate said film and unite it with said body and said backing sheet, and withdrawing the heat.
y 7. A paper backing adapted to be fixed to an element, comprising a sheet of paper having two opposed margins, and a free film of heat activatable thermoplastic adhesive portion which are unattached to Said sheet.
References Eited in the tile of this patent UNiTED STATES PATENTS Englund Aug. 17, Gottesman July 28, Arnold July 20, Rafferty Feb. 21, Elliott May l12, Winch lune 9,
FOREIGN PATENTS Great Britain Aug. 19,
osite said sheet substantially film being anchored to said n of said sheet which extends d margins and thereby proside of said central