US 3442034 A
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Description (OCR text may contain errors)
May 6, 1969 F. C. MOORE ET AL.
DIsPo'sABLE SURGEONS BOOT Filed March 3, 1966 /NVE/VTOR. FRAN/(C M0095 LEO/V PERK//VSN United States Patent O 3,442,034 DISPOSABLE SURGEON S BOOT Frank C. Moore, 3935 Arthington Blvd., and Leon R. Perkinson, 4925 Ef 40th St., both of Indianapolis, Ind. 46226 Filed Mar. 3, 1966, Ser. No. 531,461 Int. Cl. A43b 3/16 US. Cl. 36-7.1 15 Claims ABSTRACT OF THE DISCLOSURE A disposable sanitary foot covering comprising a pair of superimposed layers of sheet material marginally heat sealed together by an intermediate film of impervious thermoplastic material having a lower fusing temperature, the upper of said layers being of porous or open-celled expanded plastic material and the bottom layer being a suitable fabric material having a melting point higher than the fusing temperature of the intermediate film, said upper layer having an opening therein for the insertion of a wearers foot.
This invention relates to improvements in surgeons boots, or shoe coverings, and to the method and materials for making the same. More particularly, this invention relates to a disposable, or one-time use, shoe covering of unique design, fabrication and material combinations, which is characterized by its low cost, ease of placement on, or removal from, the foot or shoe of the wearer, comfort and safety during use, strength, water-proofness, porosity to allow breathing through the upper while having an impervious sole, and being adaptable to asceptic conditions and techniques.
Disposable foot coverings designed for wear over the shoes are available in a number of designs and constructions. They are provided with elastic tops, folding tops, laces, tie-strings, draw-strings, snap fasteners, and the like, to facilitate application to the shoe of the wearer and subsequent removal. The prior art suggests many fabrics and materials of construction, including natural and synthetic fibers, with or without reinforcing members. Some attention has been given to the compositions of the parts or fabrics used in the construction, i.e., the soles, in order to provide high conductivity for grounding of a static charge in the wearers body. Fabrication and assembly has been by gluing. stitching, welting and heat-sealing the component parts.
In general, the prior art boots, although serving their intended purposes, have certain disadvantages, such as being cumbersome to use or apply and remove from the shoe or foot, expensive, and not offering all-around satisfactory performance as far as hospital use is concerned. It is highly desirable that a shoe of this type has a combination of properties and utilities including simplicity, disposability (low cost), comfort, safety, capability of sterilization, water-proofness, and good appearance. An article of this nature should possess all of these qualities in order to promote its use.
This invention is based on the discovery that such a shoe covering can be provided by bringing together the combination of a sole-piece, made of a suitable fabric or paper, having an impervious polyalkylene insole covering thereon and a fiexible, elastic and porous upper portion, wherein the parts so interlock as to form a unitized lightweight shoe covering which overcomes the disadvantages of the prior art devices. In attempting to find a way to form a heatseal 'between an open cell foamed or expanded plastic material and a thermoplastic sheet material, to provide 4a moisture-proof sole and a breathing upper, it was found that a good bond was had only when the thermoplastic 3,442,034 Patented May 6, 1969 material was disposed between the foamed material and a base material having substantially the same or greater melting point than the foamed material. Thus fabric suitable as a sole could be rendered impervious to moisture or dirt by means of a cover film of a suitable polyalkylene plastic material, and then readily joined to a foamed plastic upper by heat-sealing the parts into a laminated unit at the fusing temperature of the upper material, The reason for this is that the high melting base material or fabric maintains the orientation of the comparatively low melting polyalkylene material even though it is subjected to the two or three times greater fusing temperature of the foamed material during the heat-sealing process. Thus the three layers of different materials are readily and permanently bonded together.
Polyalkylene covered inner sole surface not only effects a strong seal in the laminaion of the sole and upper, but also provides a smooth insole surface which facilitates putting the boot over a shoe, and provides an impervious barrier to dust, moisture, and bacteria from the wearers foot or shoe. This makes it possible to use inexpensive materials, such as paper, for the sole, which gives a non-skid footing even when wetted. Also the use of the polyalkylene lm between the sole and the upper allows the fabrication of the top or upper part of the boot from a porous or open cell stretchable material, such as a foamed polyurethane, which serves as a close-fitting shoe covering that breathes, can be of various colors, and is easily applied to and removed from the shoe. A further advantage of the instant shoe covering is that it lies fiat for packaging and when stored or not in use, the upper stretching to accommodate the 3-dimensional shape of the wearers foot or shoe when applied.
It will thus be seen that the primary object of this invention is to provide an inexpensive, disposable, easily manufactured, surgeons boot having a Water-proof sole and a comfortable, porous upper.
Other objects of this invention are to provide a disposable surgeons boot which is easily made conductive and is non-skid strong, easily applied and removed, ladaptable to asceptic conditions and techniques, and is particularly adapted for sterilization for use in a hospital operating room with complete safety; to provide a laminated, heat-sealed shoe covering comprising the combination of a sole made of porous, fibrous material, a polyakylene insole, and a porous, stretchable upper; to provide laminated 3piece or 2-piece shoe covering having an arcuate opening in a flat stretchable upper sheet-like element which facilitates use as a shoe or foot covering; and to provide an improved method of forming laminations of high fusing temperature materials with materials having a low fusing temperature.
A specific embodiment of this invention is shown in the accompanying drawings, wherein:
FIG. l is a perspective view, showing the improved shoe or boot upon the foot of the wearer;
FIG. 2 is a partial cross-sectional view taken along lines 2-2 of FIG. 1;
FIG. 3 is a top plan view of a surgeons boot embodying this invention as it appears in its at form before insertion of the wearers shoe or foot therein;
FIG. 4 is a partial longitudinal cross-sectional view as shown in FIG. 3, but with a conductive strip attached for grounding the wearers foot;
FIG. 5 is a perspective exploded view showing the parts comprising the boot assembly; and
FIG. 6 is a fragmentary view in cross-section, showing a particular form of heat-sealed laminated assembly.
The inventive concept involved in this disclosure is to provide a moisture and dirt impervious surgeons boot of inexpensive sheet materials, including an upper made of a stretchable open cell foamed or expanded plastic material, by marginally heat-sealing a lamination comprising the sole and upper member and an interposed barrier element of a suitable polyalkylene material.
In the forms shown in the drawings, the improved boot 10 comprises 3 sheet-like elements, namely, an upper portion 12, an insole 14, and a sole 16, bonded together at a heat-sealed margin or edge 18, and provided with a conductor strip 20, and an arcuate lobed cut 22 providing a tongue member 24 and an opening 26. The parts are contoured to form a relatively wide counter portion 28 with the margins converging toward the toe to provide a somewhat narrower and rounded toe portion 30. In FIG. 1 the boot 10 is shown fitted closely over the foot 32 of the wearer by insertion of the foot through the opening 26 under the tongue 24, the counter portion 28 being drawn up to accommodate and embrace the heel of the wearers foot or shoe. As shown in FIGS. 3 and 4, the boot is initially flat or sheet-like and, in order to be opened to receive the wearers foot or shoe, is made of an almond-shaped contour, that is wide at the middle and rear 4portions and somewhat narrowed toward the toe portion. This almond shape of the fiat article is distinctive and important in order to provide a device of this type which will adequately enclose or surround the wearers foot and shoe.
The top 12 is a stretchable porous material such as an ester type of foamed plastic or an ether type of foamed plastic or mixtures thereof. The insole 14 is an impervious film or sheet such as a polyalkylene coating, which may be colored or clear, and the sole 16 may be made of any of a wide variety of materials such as paper, rubber, canvas, cloth, felt, and the like. The coating or film 14 may be adhered to the entire top surface of the sole member 16', as shown in FIG. 4, or may be bonded to the sole member at the margins only, as shown in FIG. 6. In FIGS. 1 and 2, the conductive strip 20 is a fiexible element and is shown to have a portion 34 thereof extending along the instep of the boot 10 and fastened to the sole 16 by any suitable means, and the upright portion 36 is free to form a tab 38 which may be inserted between the wearers shoe 40 and the foot 32. The conductive strip 20 may be any elongated, flat flexible conductor such as an aluminum or `copper foil, or laminated foil and paper strip. A conductor such as this is readily fastened to the sole at the instep, or opposite the lobed cut 22 by means of a suitable adhesive, leaving free portion 36 extending therefrom (see FIG. 4). After the boot 10 has been placed on the foot or shoe, the end portion 38 of the conductor is easily tucked into the wearers shoe into contact with the wearers skin or stocking, thus providing an electrically conductive path from the wearer to the floor.
As seen from FIGS. 3 and 4, the fabricated boot, When not in use, lies fiat with the tongue 24 coming to a position adjacent the edge of the heel portion 28. By grasping the tongue 24 and lifting the same, the arcuate cut 22 and lobes 26 open to allow the toe of the persons foot or shoe to be inserted. Since the insole 14 is a smooth plastic, having a low coefficient of friction, and the sole 16 is paper, felt, or similar fabric, it does not slide on the floor, and thus the foot or shoe slides easily into position within the toe part 30 of the boot. The counter portion 28 is then stretched back and up over the heel of the shoe of the wearer so as to closely embrace and enclose the same. As shown in FIGS. 1 and 2, the wearers foot or shoe is thus completely enclosed by the boot, and there is substantially no exposure to cause contamination of the operating room oor.
In FIG. a precut upper portion 12, plastic film 14 and a precut sole 16, are shown, along with a conductive member 20, in an exploded view. In actual fabrication the film 14 is applied to the top surface of the sole 16 and then the top portion 12 is laid thereon and the edges are heat-sealed together. Conductive member 20 is then placed with the portion 34, glued or otherwise suitably bonded against the middle portion of the bottom surface of the sole member 16, only that part of the conductive member 20 extending beyond the edge of the sole being left free. When thus assembled the parts will have the appearance shown in FIGS. 3 and 4.
In FIG. 6 another form of seam is shown wherein a top layer 42 of foamed plastic material, an intermediate layer of a thermoplastic sheet 44, and a bottom layer 46 comprising a sheet of foamed plastic or other foraminous material are heat-sealed together at 48 to form a unitized structure. In this instance the thermoplastic sheet 44, which may be a polyalkylene film, only adheres t-o that portion of the layers 42 and 46 where heat has been applied, i.e., at the seam 48. Thus that portion of the polyalkylene film, inwardly of the seam is unattached to the bottom or sole layer 46. The fact that the margin of the polyalkylene film is disposed between the top and bottom sheets 42 and 46 allows the maintenance of the orientation of the film material even though the heatsealing temperature necessary to fuse the foamed material is several times the fusing temperature of the film. Thus a firm and stable bond is had to maintain the 3- layer lamination of the different materials.
Any thermoplastic material having a melting point or fusing temperature in the order of to 250 F. may be used as the intermediate film or coating 14 or 44. Preferably polyalkylene polymers are used as coating materials, i.e. the insole 14 may comprise any of a broad class of polymerized ethylene, propylene, ybutylene, and the like. Illustrative of these is polyethylene. The polyethylene resins having molecular weights of about 10,000 or higher are transformed into viscous liquids by heating to temperatures of about 200 to 230 F. Thus the polymers are easily processed by calendering, or by the use of the hot melt solution coating and fiame spraying methods. The hot melt solution coating, and flame spraying techniques can be used in applying the film 14 to the sole member 16 as an all-over directly adhered surfacing. It is only necessary to apply a film of about 0.01 to 0.001, or less, inch in thickness, as an al1-over coating on the sole member 16.
The polyalkylene polymers such as polyethylene are particularly adaptable as the insole coating because of their ease of application, flexibility, toughness, inertness, low rate of water vapor transmission, and low water absorption. In addition, these materials are non-toxic, odorless and tasteless. They withstand temperature up to 250 F. and have brittle points below 95 F. Also polyethylene has good form stability and remains unchanged in chemical and physical properties with age.
Other film and sheet plastic materials that can be used for the intermediate layer in our improved surgeons boot, are cellophane, cellulose acetate, cellulose acetate butyrate, cellulose nitrate, ethyl-cellulose, non-rigid polyvinyl chloride, vinyl chloride-acetate, co-polymers, polyvinylidene chloride, vinylidene chloride co-polymers, polyvinyl butyral, polystyrene, polyamide (nylon) and rubber hydro-chloride.
The foamed plastic suitable for one or more of the laminations (i.e. the top 12 and the layers 42 and 46) of the articles produced in accordance with this invention can be of several types including, but not limited to, foamed polyvinyl chloride, foamed polyethylene of the flexible type, foamed polyurethane and other flexible foams of a straight chain polyester that can be made with an open cell structure. Preferably the foam is of the ester type, i.e. polyurethane, having an elasticity of about 200 to 400% or higher. Ether type polyurethane can be used when desired, but such will have lower elasticities in the order of only 50 to about 100% It will thus be seen that the instant invention relates to a heat-sealed sandwich type structure and the method of its formation and is based on the discovery that the use of a film of a low melting point thermoplastic between two similar or dissimilar materials having a much higher melting point, including a foamed type of plastic, unexpectedly allows heat-sealing the layers together. The invention has been illustrated by sandwich constructions comprising the lamination of (a) Polyurethane, polyethylene and paper layers;
(b) Polyurethane, polyethylene, and polyurethane layers, in the lamination (a) the polyethylene is adhered to the entire surface of the paper, and the high melting point polyurethane is adhered Ionly to that part of the lamination which is compressed and heated at the margins and which may be in the form of a seam in the construction of a surgeons boot or shoe covering, or may be in the form of a completely sealed and unitized sandwich, i.e. for insulation or cushioning purposes. In the lamination (b) the polyurethane layers adhere to the intermediate polyethylene film at the seam only. In either case the presence of the high melting point bottom layer maintains the orientation of the low melting point intermediate layer so that a firm and permanent heat-seal bond is made.
In a practical surgeons boot embodiment of the before mentioned combination (a), the polyurethane sheet was 1/16 inch thick, and the polyethylene material was applied as an over-all coating on kraft crepe paper; and in a similar embodiment of the combination (b), each of the polyurethane layers was a sheet 1/16 inch thick and the intervening polyethylene material was a sheet 0.001 inch thick. The lamination comprising the 'boot was of generally almond-shaped contour 7 inches wide across the arcuate cut, 13 inches long and 4 inches wide at about 11/2 inches behind the toe end. The arcuate cut was made to extend forwardly from a point 31/2 inches inward from the heel end along the center line of the boot to about 1 inch from each side of the boot with the ends of the cut terminating 51/2 inches inward from the heel end. A boot of this size fitted over a size 8 shoe to fully enclose the same as shown in FIG. 2.
From the foregoing it is apparent that this invention concerns plastic laminate constructions, including a layer of an expanded plastic sheet material, an intermediate film of a thermoplastic material, and a second layer or base, of any suitably high melting point sheet material, wherein a portion or all of each of the layers is joined to the intermediate film by heat sealing. The heat-sealed portion may be in the form of a seam or arrangement of seams, or may cover the entire adjacent areas of each member in the laminate. It is also apparent that two or more such laminate constructions can be sealed one to the other to form multi-layer constructions, the joint being effected by an intervening layer of a low melting point thermoplastic material. The base layer of sheet material can be paper, rubber, felt, cloth, or substantially any desired base material.
A surgeons boot made from such a lamination and comprising an upper of open cell expanded synthetic material in sheet form, marginally heat-sealed to any suitable lbase material by means of an intervening thermoplastic material, provid-es a boot having all of the before-mentioned desirable characteristics, and particularly those of a water-proof base and a breathing upper.
1. A protective foot covering comprising a lamination of a first layer made of foamed plastic, a second layer of a thermoplastic film, and a third layer of a material having a higher fusing temperature than the thermoplastic film, said foot covering having an opening for entry of a wearers foot between the first and second layers.
2. A protective foot covering as defined by claim 1 wherein the first layer is a sheet of expanded plastic material of the open-cell type.
3. A protective foot covering as defined by claim 2 wherein the bottom layer is a sheet of fibrous material.
4. A protective foot covering as defined by claim 2 wherein the bottom layer is a sheet of expanded plastic material.
5. A protective foot covering as defined by claim 2 wherein the second layer is a polyalkylene film.
6. A protective foot covering as defined by claim 2 wherein the first layer is a sheet of foamed plastic material from the group consisting of expanded polyethylene, polyvinyl chloride, and polyurethane.
7. A protective foot covering as defined by claim 6 wherein the second layer is a polyalkylene film.
8. A protective foot covering as defined by claim 6 wherein the bottom layer is a sheet of fibrous material.
9. A protective foot covering as defined by claim 7 wherein the bottom layer is a sheet of expanded polyurethane of the open-cell type.
10. A protective foot covering comprising a pair of superimposed elongated and terminally rounded sheets of material having a generally almond-shaped outline, the upper one of said sheets being formed of a foamed plastic of the open-cell type and having an opening therein for insertion of the wearers foot, the other of said sheets being formed of `a material having a relatively high fusing temperature, and a polyalkylene film interposed between said sheets and having a lower fusing temperature than either of said sheets, said foamed plastic sheet and said other sheet being fused to said film at the marginal edges thereof.
11. A protective foot covering as defined by claim 10 wherein the upper sheet is of expanded polyurethane and the said other sheet is of paper.
12. A protective foot covering as defined by claim 10 wherein the upper sheet and the said other sheet are of expanded polyurethane.
13. A moisture impervious laminate comprising a first layer of foamed plastic sheet material, a second layer of a polyalkylene film, and a bottom layer of a material having a higher fusing temperature than said second layer, the said layers being fused one to the other at their margins.
14. A moisture impervious laminate as defined by claim 13 wherein the first layer is expanded polyurethane, and the second layer is polyethylene.
15. The method of making a moisture impervious lamination of an expanded plastic sheet material and a high melting point base material which comprises interposing a polyalkylene film between said materials and then heat-sealing the assembly of said materials by fusing the polyalkylene film in situ.
References Cited UNITED STATES PATENTS 2,721,399 10/1955 Emmer 36-7.1 3,013,184 12/1961 Adams 36-1 X 3,032,898 5/1962 Servin 36-9 3,052,046 9/ 1962 Kramer 36-9 3,308,562 3/1967 Zimmon 36-9 X PATRICK D. LAWSON, Primary Examiner.
U.S. Cl. X.R. 161--182; 317-2