US 3345668 A
Description (OCR text may contain errors)
Oct. 10, 1967 J FORREST ABRASIVE ARTICLE Filed April 16, 1965 I1\/VENT0R. JOHN L FORREST BY 75o; M
ATTCRNEY United States Patent ()fiiice 3,345,668 Patented Oct. 10, 1967 3,345,668 ABRASIVE ARTICLE John L. Forrest, Windsor, N .Y., assignor to General Aniline & Film Corporation, New York, N.Y., a corporation of Delaware Filed Apr. 16, 1965, Ser. No. 448,789 2 Claims. (Cl. 209) ABSTRACT OF THE DISCLOSURE The invention is concerned with an abrasive article comprised of a highly porous, lofty, non-woven and uniform pad-type structure of unitary construction formed of a plurality of interlaced, randomly disposed, tridimensionally extending, narrow strips of a film-forming, pre-forrned, organic plastic, the plastic exhibiting substantial resiliency, flexibility, and strength upon prolonged subjection to water and/or oil and the like, and wherein the plastic strips are firmly bonded at their many spaced points of mutual contact, thereby defining a three dimensional web type structure having a labyrinth of intercomrnunicating voids, the latter constituting at least about 50%, and preferably at least about 75%, of the total volume occupied by the entire pad-type structure.
The present invention relates, in general, to abrasive articles and, in particular, to non-woven abrasive articles comprising a highly porous pad structure having significant utility in a variety of cleaning applications wherein hand-scouring operations are performed to remove food and debris from food-handling equipment and utensils.
An object of this invention is to provide an abrasive article which is advantageously adapted for the handscouring requirements performed as a matter of course in kitchenware cleaning operations.
Other objects and advantages of this invention will become apparent from the following detailed description thereof.
In accordance with the foregoing objects of the invention abrasive articles have been devised comprising a highly porous, lofty, non-woven and uniform pad-type structure of unitary construction formed of a plurality of interlaced, randomly disposed tri-dimensionally extending, narrow strips of a film-forming, pre-formed, organic plastic, said plastic exhibiting substantial resiliency, flexibility and strength upon prolonged subjection to water and/or oils and the like, and wherein the said plastic strips are firmly bonded at their many-spaced points of mutual contact, thereby defining a three-dimensional webtype structure having a labyrinth of intercomrnunicating voids. the latter constituting at least about 50%, and preferably at least about 75 of the total volume occupied by the entire pad-type structure.
Abrasive articles of the above-described type are of extremely low density owing to the presence therein of many relatively large intercomrnunicating voids. Such pads have been found to exhibit a remarkably effective abrasive action, contrary to what might normally be expected for abrasive articles so constructed. In fact, one of the highly distinctive features characterizing the abrasive articles of the present invention is their unique applicability for use in removing substantial quantities of food and other waste matter from the above-mentioned kitchen ware articles, whether as part of or preliminary to the final washing operation, while eliminating substantially the disadvantages attendant upon the use of metallic scouring pads. Highly significant is the further discovery that such abrasive articles possess, in addition to the foregoing features, the distinct capacity for effectively performing substantially all of the scouring operations heretofore considered as requiring metallic scouring pads. Moreover, such results are obtained without in any way deleteriously affecting the structure and/or appearance of the surfaces of the kitchenware treated therewith, including fine glassware, porcelain and aluminum cookware. Moreover, the abrasive articles of the present invention are essentially non-clogging and non-filling in nature, particularly when used in conjunction with liquids such as water, as is the case with dishwashing and cookware cleaning operations; in any event, they can be readily cleaned by simply flushing same with water whereupon they can be left to stand for extended periods without in any way detracting from their usefulness.
Unlike scouring pads fabricated wholly or partly with metal, the abrasive articles of the present invention maintain their shape, resiliency and other physical characteristics over extended periods of time and use despite being subjected to relatively severe scouring operations. This is readily understood since the problems of particle shredding, oxidation, attrition and the like, which arise with the use of metallic scouring pads, are substantially nonexistent with the abrasive articles of the present invention. The latter are characterized by substantial flexibility, toughness, durability and compressibility, and if compressed, as would be the case in actual use, recover substantially completely to their initially uncompressed form.
As pointed out hereinabove, the total volume of voids constitutes at least about 50%, and preferably about and more of the total volume occupied by the pad articles of the present invention. Accordingly, such pads are highly translucent to the extent that when held up to light, practically all of the light incident thereupon passes therethrough, thus registering on the eyes of the viewer.
The extreme porosity, and low density of the abrasive articles provided by the present invention are graphically illustrated in the accompanying drawing. The drawing is a schematic representation, greatly enlarged, depicting the mutual entanglement characterizing the intertwined ribbons of pre-formed organic plastic present in the low density abrasive articles of the present invention. As will be apparent upon reference to the drawing, the interstices or voids constitute a substantial portion of the total volume occupied by the pad structure. As will also be apparent, the mutual intertwining or entanglement of the plastic strips, which extend randomly throughout the pad volume, serves to define a tri-dimensionally extending network of relatively large intercommunicating voids. This high void-volume feature produces an abrasive article which is highly resilient and elastic whereby a highly effective and unique abrasive action is obtainable therewith.
In overall texture, the porous pad articles of the present invention are somewhat billowy, possessing considerable loft, and resemble a resilient spongy tuft. When held up to a stream of water, the stream is diverted only slightly in passing through the pad structure, clearly evi dencing the extreme penetrability thereof.
Although not critical to the results obtainable in accordance with the present invention, it is nevertheless found that the best results are obtainable when the total void volume of the pad structure is maintained within the range of from about 75% to and higher based on the total pad volume. Pad structures wherein the void volume is substantially below this preferred range, although useful for the purposes described herein, have proved to possess somewhat inferior performance characteristics. However, when the voil volume is decreased to values less than 50%, it s found that the outstanding and advantageous properties provided for by the pad structures of the present invention diminish relatively rapidly.
As pointed out previously, the abrasive articles of the present invention are completely devoid of metallic substances of any kind. In fact, it is essential to the results obtainable in accordance with the present invention that the pad be constructed solely of pre-formed organic plastic ribbon strips. Plastic materials suitable for use in fabricating the pad structures of the present invention are in general those capable of being drawn into selfsupporting foils or films, i.e., so called film-forming plastics and which in addition possess to a significant extent the required properties of toughness, durability, resiliency, solvent resistance and the like, as more fully described hereinabove. As exemplary but by no means exhaustive thereof, there may be mentioned the following: regenerated cellulose esters, e.g., cellulose nitrate, cellulose acetate, cellulose tri-acetate, cellulose propionate, cellulose butyrate, cellulose acetate butyrate, cellulose acetate propionate and the like; cellulose ethers, e.g., ethyl or benzyl cellulose; synthetic linear polymeric condensation polyesters derived from glycols and dibasic acids such as polyethylene terephthalate (sold under the trade name Mylar) and especially those polyesters which exhibit, as adduced from characteristic X-ray diffraction patterns, molecular orientation along the fiber axis; superpolyamides (e.g., nylon), polyesteramides, synthetic vinyl type resins, e.g., homopolymers and interpolymers of ethylene, propylene and the like, vinyl chloride, vinylidene chloride, vinyl acetate and the like, maleic anhydridevinyl methyl ether copolymers and the like.
It should be understood that the foregoing listing is partial only and is not in any sense intended to be limitative of the plastic materials contemplated for use in the invention described herein.
Although any suitable plastic material can advantageously be used in the structure provided by the present invention so long as they meet the requirements with respect to the properties enumerated hereinabove, particularly good results are obtained with pad structures fabricated in whole or in part of cellulose acetate, cellulose triacetate and/or polyethylene terephthalate. The sponge pad may, of course, be fabricated from two or more of the plastic materials contemplated herein which in some instances may be preferred. A particularly valuable source of the plastic materials is the photographic film industry which'offers an ample supply of scrap film base in the form of edge trimmings and the like. Since the scrap film base as obtained therefrom is pre-fabricated in the required strip or ribbon form, the need for further trimming, cutting, or other shape-forming operations which might otherwise be required is reduced considerably. It is conventional practice in the photographic film industry to provide such film base material, which serves as a support for further overcoating layers, lightsensitive and otherwise, with so-called subbing layers. The latter function principally as adhesives, thereby enhancing the dimensional stability of the composite film structure and consequently its resistance against delamination. These subbing compositions are of varied constitution but in general employ as the essential ingredient a relatively tacky polymeric substance which may be synthetically derived, e.g., synthetic resin materials, or of animal origin, e.g., proteinaceous materials such as gelatin. As representative of the subbing compositions commonly employed with film bases of the type contemplated herein there may be mentioned, by way of example, copolymers of vinylidene chloride with other vinyl type monomers copolymerizable therewith such as vinyl acetate, vinyl chloride, vinyl bromide, acrylonitrile, styrene, ethyl vinyl ether, butyl vinyl ether, N-vinyl phthalimide, N-vinyl succinimide, N-vinyl carbazole, methylene diethyl malonate and the like, and mixtures of two or more of the foregoing. Particularly good results are obtained with film bases, e.g., Mylar, which have been coated with a subbing composition comprising a copoly- 4 mer of vinylidene chloride and acrylonitrile containing at least 50% by weight of the former.
The dimensions of the plastic ribbon strips are not particularly critical, due regard being had to the resiliency and toughness ultimately desired in the pad structures fabricated therewith. In general, it is found that the porous pad structures constructed of organic plastic ribbon strips, the latter having an average thickness of from about .003 to about .007 inch and an average width of about A to /8 inch, are particularly conducive to the results contemplated herein. By and large, the length of the plastic strips is likewise not critical but should be selected so as to be consonant with the dimensional stability desirably characterizing the resultant pad structure. In general, it is found that lengths ranging from approximately /2 to 4 inches and more are eminently suitable for use in the present invention.
In the interest of obtaining a maximum loft, void volume and three-dimensionality, it is recommended that all or a substantial amount of the plastic strips be crimpedset prior to constructing the pad article therewith. However, the crimping expedient is not necessary where plastic strips are employed which readily interlace with one another to form and retain a highly open, lofty relationship in the resultant sponge structure.
The procedure observed in producing the sponge pads of the present invention is as follows. Assuming the availability of the plastic material in pre-fabricated strip or ribbon form, such as would be the case where photographic scrap film base and/or edge trimmings are employed, the said plastic strips are first twisted and entangled into a ball of a size easily and conveniently accommodated by the hand. This can be readily accomplished manually by hand-forming the plastic ribbon into a clump of the desired shape and size. When proceeding in this manner, however, it is recommended that the overall size of the hand-formed ball be somewhat larger than the ultimate size desired in the final pad product produced therefrom, this allowance being made for the size reduction attributable to the thermal compression molding operation employed in forming the final pad product. An alternative and more convenient method for transforming the plurality of plastic strips into the requisite entangled web of high porosity is available with the use of commercial apparatus designed specifically for such purpose. One such apparatus, generally known as the Rando-Webber machine, is commercially available from the Curlator Corporation of Rochester, N.Y. As a preliminary operation, the mass of plastic ribbon strips can be fed into a conventional Garnett machine which functions to loosen and thereby separate the plastic strips of suitable width from the micron-sized strands in which many exist as received from the supplier, this preliminary step being desirable but by no means essential. The strips obtained from the Garnett machine as such are then transferrcd to the feed box of the Rando-Webber machine. The latter is started and adjusted so as to produce a random web of extremely low density and high porosity. Following this operation, the web can conveniently be cut into sections of the desired size. The final sponge pad is then produced by a thermal molding operation utilizing a suitable mold, the cavity shape of which corresponds to the desired shape in the final pad product. The temperature employed in the thermal-molding operation should desirably approximate the softening point temperature of the particular plastic material employed. These values, if not otherwise known, are readily capable of determination by routine laboratory procedure if not by resort to standard reference works or manufacturers specifications. However, the temperature employed should not substantially exceed the aforementioned values in order to avoid possible shape-distortion of the plastic ribbon elements with consequent diminution in the final product of such desired properties as porosity, resiliency, strength and the like.
The heat-treatment step can also be accomplished by such other means as simple immersion of the pre-fabricated web of plastic ribbon strips in a suitable liquid medium, the latter being maintained at a temperature closely approximating the softening point of the plastic material. Alternatively, this operation can be effectively carried out by known induction-heating techniques.
Regardless of the particular method of heattreatment employed, be it via thermal molding, immersion, or induction heating techniques, it should also be noted that the cutting of the plastic web to the ultimate size desired can just as easily be effected following the heat-treatment step. For example, the heat-treatment operation might Well be carried out on bulk quantities of the plastic web material, i.e., prior to the actual step of producing the pad in final form. If the heat-treatment technique employed involves the use of forms, molds and the like, the latter can be readily obtained in sizes adapted to accommodate bulk quantities of feed material which would, of course, in this case be organic plastic in strip or ribbon form.
In some cases it may be desirable to further enhance the dimensional stability of the plastic web structure by some suitable operation which results in a firmer bonding of the plastic ribbon strips at their spaced contact points. This can be readily accomplished, for example, by merely immersing the web in a suitable media which is a solvent for the plastic material, thereby tackifying the surface of the said plastic strips rendering same highly susceptible of firmly bonded mutual contact. The foregoing, which might be termed a self-bonding technique is especially effective where the plastic strips employed are not otherwise provided with a suitable bonding agency such as non-subbed photographic plastic film base. However, improved results are also evidenced by the foregoing technique even in cases where the plastic film base as supplied includes as an integral part of its structure one or more subbing, i.e., adhesive layers.
The following examples are given for purposes of illustrating the present invention and are not to be regarded as limitative thereof.
Example I Approximately 40 grams of photographic film base comprising a base layer of polyethylene terephthalate is hand-formed into a tangled sponge-like mass of a size and shape easily accommodated by the hand and closely approximating that of commercially available hand scouring pads, and thereafter transferred to a heated mold which is maintained at a temperature of 400 F. The shape of the cold cavity is such as to produce a molded product having a shape and form of commercially available hand scouring pads. The mold is then capped thereby enclosing and sealing the plastic ribbon strips completely within the cavity portion thereof. The temperature of 400 F. is maintained for a period of approximately minutes. The mold is then allowed to cool to approximately room temperature whereupon it is opened and the heat-set plastic tangled mass which is now a unitary Web-like structure is removed therefrom.
The sponge pad thus obtained when tested to determine its usefulness as a scraping and/or scouring agent is found to be substantially devoid of the undesirable features pointed out previously as inherent in the use of metallic scouring pads. For example when fine porcelain is subjected to vigorous scouring with the pad of Example I, there are no visible after effects such as dark metal stains, scratches, mars or other irregularities at the porcelain areas so treated. Like results are obtained when glassware, plastic ware and aluminum cookware are subjected to similarly vigorous scouring with the pad article of Example I.
However, when the foregoing tests are repeated in all particulars, but substituting steel wool for the plastic web of Example I, employing equally vigorous scouring action for an identical period of time, it is found that the sur- 6 faces of the fine porcelain may be darkened by embedded metallic particles from steel wool. Glassware, plastic ware and aluminum cookware, respectively, are as a result of such treatment, roughened to an extent easily detected by the naked eye.
Moreover, a close visual examination of such surfaces reveal the presence of embedded metal scratches, pocks and other surface irregularities clearly indicating the undesirably severe abrasiveness of steel wool pads even under relatively moderate conditions of use. Furthermore, the tendency of steel wool pads to shred in use is clearly manifested by the presence of metallic deposits, e.g., particles of steel wool fibers, in and around the scoured areas of the above-described kitchenware.
Although the foregoing examples illustrate the preparation of the pad structure of the present invention according to procedures involving the use of scrap film base as the starting material, it should be understood that the present invention is not necessarily limited thereto. In some instances, the plastic material may be obtained in the form of the raw bulk polymer. However, this presents no particular problem since such material may easily be converted to the desired strip or ribbon form by such purely mechanical operations as cutting, rolling, etc. For example, the plastic raw material can be rolled into sheet or foil form of the desired average thickness by the use of stainless steel rollers heated to temperatures approximating the softening point of the particular plastic, after which the resultant sheet product can be cut to size as desired. The plastic in ribbon form, of course, serves as the feed to the web-forming apparatus such as that particularly referred to hereinabove.
According to a further modification of the present invention, it is possible to produce sponge pad structures which are colored in one or more pleasing hues and shades. For example, multi-colored plastic strips may be used in order to obtain a mixed color scheme in the final sponge product or alternatively, singly-colored pads can be readily produced. In addition, the plastic strips may have the colorant applied thereto in the form of various ornamental designs, such as speckles, stripes and the like. The method by which the desired color is imparted to the plastic material depends to a great extent, of course, on the particular form in which the plastic is supplied. For example, the desired colored form may well be obtainable as such in the form of scrap film base and/ or raw polymer product. In any event, it can readily be produced by the use of conventional dyeing techniques such as spraying, padding and/or immersion and the like. Furthermore, in those instances where the plastic polymer is especially produced for use in fabricating the abrasive articles of the present invention, the desired coloring result can be obtained by including the dye, pigment or other colorant agent in the solution of polymer. It is obvious, of course, that even where the plastic material is obtained in either bulk polymer form or as scrap film base, that solution dyeing techniques are equally operable. This would require merely dissolving the polymer in a suitable solvent in the presence of one or more coloring agents.
As mentioned hereinabove, in the appropriate circumstances it may be deemed desirable and/or necessary to provide the plastic sheet material with one or more adhesive coatings to insure the obtention of firmly bonded contact at those points where the plastic ribbons mutually intersect. Subbing composition of the type enumerated hereinbefore are excellent adhesives for the base materials contemplated herein and accordingly are recommended for use in the present invention. These subbing compositions may be deposited in layer form on the plastic sheet by any of the usual coating methods used in the plastics coating field, e.g., by immersion of the surfaces of the plastic sheet into a solution of the coating material; spraying; beading or coating from a hopper provided with a doctor blade, etc. Followingthis operation, the coated plastic is dried by conventional means such as by heating same to moderately elevated temperatures and/or by passing a current of Warm air thereover. The highly porous web of the present invention may also be used in 0011- junction with additional elements attached thereto such as backing elements, e.g., sheets and/ or holding blocks, etc., thereby rendering such articles more efliciently adapted to hand use.
While the invention has been described in a preferred embodiment, variations and modifications will obviously become apparent to those skilled in the art. Accordingly, it is intended, by the appended claims, to cover all such variations and modifications as fall within the scope thereof.
What is claimed is:
1. A unitary pad structure of high-porosity comprising a uniform, non-woven, lofty, three-dimensional webtype structure having a plurality of randomly tri-dimensionally extending, durable, tough, resilient organic plastic ribbon strips,
said strips composed of a subbed photographic film base wherein the subbing material of said photographic film base constitutes the binder material whereby said strips are firmly bonded at their spaced points of contact; the mutual entanglement of said strips defining a labyrinth of tri-dimensionally extending intercommunicating voids,
said voids constituting at least about 50% of the total volume occupied by said pad structure, wherein said pad is additionally characterized by pronounced flexibility, elasticity and compressibility, and upon release of pressure applied thereto, said pad is capable of recovering substantially completely to its initial uncompressed form.
2. The unitary pad structure of claim 1 wherein the subbing composition comprises a synthetic polymeric material.
References Cited UNITED STATES PATENTS 2,327,199 8/1943 Loeffier 15209 X 2,601,771 7/1952 Cameron 15209 X 2,743,511 5/1956 Genovese 15209 X 2,958,593 11/1960 Hoover et al. 15-209 X 3,252,176 5/1966 Gropper 15209 3,284,963 11/1966 Lanham et al 15209 X FOREIGN PATENTS 887,829 8/ 1943 France. 303,614 2/ 1955 Switzerland.
CHARLES A. WILLMUTH, Primary Examiner.
L. G. MACHLIN, Examiner.