Abstract:
A two-layer, non-skid protective cloth or pad for use as a painter&#39;s drop cloth or as a protective pad for surfaces such as boat decks, airplane wings or other surfaces where a non-skid pad is essential. The pad has a woven upper member, typically of a cotton canvas-like material, and a lower, resilient member. The two layers are typically stitched together. The lower, resilient member typically comprises downward-projecting bumps, often of two or more different sizes. The bumps are joined by a grid of resilient material. Bumps may be formed from a foamed thermoset plastic resin. In alternate embodiments, an impervious member may be inserted between the upper and lower members. The non-skid protective cloth or pad has a Sliding Coefficient of Friction greater than 0.75 and an average Slide Angle no less than approximately 40° measured in accordance with TAPPI T548 specification.

Description:
RELATED APPLICATIONS 
     This application is a Continuation-in-Part of U.S. patent application Ser. No. 12/460,763 filed Jul. 27, 2009 for NON-SKID PROTECTIVE CLOTH OR PAD that is incorporated herein in its entirety by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention pertains to protective cloths or pads and, more particularly, to a protective cloth or pad that has a non-skid backing to hold the cloth or pad in position during use. 
     BACKGROUND OF THE INVENTION 
     Protective cloths and pads are well known and widely used. Such items range from simple thin polyethylene sheets used to protect surfaces during painting or similar operations to woven fabric (e.g., canvas) drop cloths to quilted protective pads used by furniture movers and the like. For simplicity, the term drop cloth as used herein refers to any and all such cloths and pads, regardless of material or construction. 
     In a typical use, drop cloths are placed on floors to provide protection. A common and serious problem is that frequently the drop cloths of the prior art may slip and slide relative to the floor upon which they are laid. Such slippage may range from a mild annoyance to a serious safety hazard when a drop cloth is placed upon a level floor. However, once such a drop cloth is used on a surface other than a level floor, the consequences of such slippage become much more serious. For example, drop cloths are commonly used to protect stairs. If the drop cloth slips, it is not uncommon for a person ascending or descending the stairs to slip and potentially tumble to the bottom of the stairs. Serious injuries frequently result from such a fall. 
     DISCUSSION OF THE RELATED ART 
     Several attempts have been made in the prior art to provide a non-slip surface for drop cloths and the like. For example, U.S. Pat. No. 152,451 for IMPROVEMENT IN WATER-PROOF FABRICS, issued Jun. 30, 1874 to George M. Allerton discloses a woven woolen cloth having one surface covered with a rubber film. 
     U.S. Pat. No. 1,728,545 for LINEMAN&#39;S BLANKET, issued Sep. 17, 1929 to Fred L. Haushalter provides a dielectric structure formed by a rubber insulating sheet and a fabric backing sheet to prevent stretching of the rubber. 
     U.S. Pat. No. 1,928,943 for MATTRESS PROTECTOR, issued Oct. 3, 1933 to John L. McKay teaches a waterproof sheet having eyelets disposed near its corners. Loops attached to the eyelets are used to secure the mattress protector, thereby preventing the slipping of the mattress protector on the mattress it is protecting. 
     U.S. Pat. No. 2,274,468 for FLOOR COVERING issued Feb. 24, 1942 to Harry W. Bell provides an improved type of floor mat. It is an object of this invention to provide a floor mat which affords a high degree of traction. 
     U.S. Pat. No. 3,488,684 for FLOOR COVERING issued Jan. 6, 1970 to John C. Wrightson shows a quilted, three-layer construction having a non-skid bottom layer for use as decorative rug. 
     U.S. Pat. No. 3,565,661 for FLOOR COVERINGS AND THE LIKE issued Feb. 23, 1971 to Alan Morley Harrison shows an improved floor covering and a process for making the same. A base material in sheet form having a coating of a thermoplastic material such as polyvinyl chloride impregnated with an abrasive substance in grit form. A second coating of a thermoplastic material is preferably applied over the first coating also containing an abrasive in grit form to which silicon carbide is sprinkled thereover. The tread surface of the floor covering is embossed to provide small indentations therein. 
     U.S. Pat. No. 5,567,497 for SKID-RESISTANT FLOOR COVERING AND METHOD OF MAKING SAME issued Oct. 22, 1996 to Stephen A. Zegler et al. provides a floor covering comprising a floor covering face layer having a thermoplastic lower backing layer and a thermoplastic contact layer that is fusibly compatible with the lower backing layer is disclosed. The upper surface of the contact layer is fused to the lower backing layer and the lower surface of the contact layer includes a plurality of shallow thermoplastic projections which extend away from the floor covering face layer and which are sufficiently elastic to impart skid resistance to the floor covering. 
     U.S. Pat. No. 6,093,469 for MAT AND METHOD OF MAKING MAT issued Jul. 25, 2000 to Michael T. Callas discloses an entrance mat having a polypropylene greige fiber pad with a trimmed outer peripheral edge and a backing of non-skid plastic material. The backing has longitudinal treads having high friction and tacky properties which prevent creep and folding of the pad on a floor. An edge has a non-skid web secured with an adhesive to the backing and a lip extended over the adhesively secured to the trimmed outer peripheral edge. 
     U.S. Pat. No. 6,296,919 for CUSHIONED CARPETED FLOOR MAT WITH A LEAST ONE CUSHIONING INTEGRATED RUBBER PROTRUSION issued Oct. 2, 2001 to James N. Rockwell, Jr., et al. provides a cushioned floor covering article wherein the mat includes a tufted carpet placed on the top side of a foam rubber sheet and at least one foam rubber protrusion integrated within at least a portion of the bottom side of the foam rubber sheet. Such an article provides effective removal of moisture, dirt, and debris from the footwear of pedestrians through the utilization of a carpet pile component. Furthermore, the utilization of a foam rubber backing also allows for either periodic heavy duty industrial-scale laundering in such standard washing machines or periodic washing and drying in standard in-home machines, both without appreciably damaging the inventive floor covering article, such as a floor mat. 
     U.S. Pat. No. 6,610,382 for FRICTION CONTROL ARTICLE FOR WET AND DRY APPLICATIONS issued Aug. 26, 2003 to James J. Kobe et al. teaches a friction control article including a backing layer having a first surface with an array of at least 100 upstanding stems per square inch and a second surface. At least a portion of the upstanding stems is an elastomeric material and the stems have an aspect ratio of at least 1.25. The first surface has a static coefficient of friction when dry of at least 0.6 and a static coefficient of friction when wet within 20% of the static coefficient of friction when dry. The first surface has a peel strength and a tensile strength of substantially zero when engaged with another slip control article. The first surface has relatively high shear strength when engaged with another slip control article. The high shear forces are due primarily to the frictional properties of the elastomeric materials, not a mechanical interlock of the stems, such as on a mechanical fastener. 
     Published United States Patent Application No. 2001/0002615 for PROTECTIVE COVER SYSTEM, published Jun. 7, 2001 upon application by Reginald Michael Lacross et al. discloses a covering system in which a cover constructed of a flexible sheet material is suitable for placement on a floor between a door frame and a room. 
     U.S. Pat. No. 6,911,407 for NON-SLIP ABSORBENT ARTICLE issued Jun. 28, 2005 to Earle H. Sherrod et al. shows a multi-layer absorbent article suitable for use as a bed pad, a baby changing pad, a table cloth, etc. A non-adhesive, skid-resistant coating is applied to the bottom layer of the article. 
     U.S. Pat. No. 6,946,163 for SLIP RESISTANT MAT issued Sep. 20, 2005 to Ian S. Malpass et al. teaches a slip resistant floor mat composed of one or more layers of material the bottom layer of which incorporates a plurality of recessions with inset suction cups in the bottom surface of the bottom. 
     U.S. Pat. Nos. 6,961,969, 7,069,607, and 7,137,157, each for ABSORBENT TOWEL WITH PROJECTIONS, issued Nov. 8, 2005, Jul. 4, 2006, and Nov. 21, 2006, respectively, to Susan Nichols each provide a towel having a base layer with raised projections to provide a higher coefficient of static friction relative to an external surface relative to other bottom surfaces common in the prior art. 
     United States Published Patent Application No. 2006/0162073 for ABSORBENT TOWEL WITH PROJECTIONS, published Jul. 27, 2006 upon application by Susan Nichols shows a towel having a base layer with raised projections to provide a higher coefficient of static friction relative to an external surface relative to other bottom surfaces common in the prior art. 
     United States Published Patent Application No. 2007/0220673 for CLOTHING ARTICLES HAVING RAISED PROJECTIONS, published Sep. 27, 2007 upon application by Susan Nichols shows a towel having a base layer with raised projections to provide a higher coefficient of static friction than the base layer relative to an external surface. 
     United States Published Patent Application No. 2007/0275209 for NON-SKID DROP CLOTH, published Nov. 29, 2007 upon application by Anal Netravali et al. discloses a single layer plastic sheet having raised dimples on one or both sides. 
     United States Published Patent Application No. 2008/0131680 for ABSORBENT NON-SKID DROP CLOTH, published Jun. 5, 2008 upon application by Richard James Bliton et al. teaches a multi-layer article having a lofted, non-woven layer and a non-skid barrier layer bonded thereto. 
     United States Published Patent Application No. 2009/0068431 for ONE-SIDED TACKY POLYOLEFIN FILM, published Mar. 12, 2009 upon application by Martin F. Hoenigmann provides a plastic sheet with a tacky surface designed to prevent slippage of the sheet 
     None of the patents and published patent applications, taken singly, or in any combination are seen to teach or suggest the novel non-skid protective cloth or pad of the present invention. 
     SUMMARY OF THE INVENTION 
     In accordance with the present invention there is provided a two-layer, non-skid protective pad for use as a painter&#39;s drop cloth or as a protective pad for surfaces such as boat decks, airplane wings or other surfaces where a non-skid, protective pad is essential. The pad has a woven upper member, typically of a cotton canvas-like material, and a lower, resilient member. The two layers are typically stitched together. The lower, resilient member typically comprises downward-projecting, spherical, quasi-spherical, and/or amorphous protrusions often of two or more different sizes and/or diameters. The term “bump” is used herein to refer to such spherical, quasi-spherical, and/or amorphous protrusions. The bumps are joined by a grid of resilient material. In alternate embodiments, an impervious member may be inserted between the upper and lower members. 
     As the terms “non-skid” or “skid resistant” applied to articles used in trade convey little if any information regarding the performance of an article bearing such a label. Consequently, a potential user of a protective cloth or pad has no way of knowing how a particular cloth or pad so labeled will perform in a particular application and/or environment. 
     The novel structure of the non-skid cloth or pad of the present invention has been tested to determine a Static Coefficient of Friction in accordance with the TAPPI T-548 standard and a static and Kinetic Coefficient of Friction by Horizontal Plane in accordance with the ASTM C1028-07 standard. This testing is discussed in detail hereinbelow. The acronym “TAPPI” stands for Technical Association of the Pulp and Paper Industry. While the novel non-skid drop cloth of the present invention is not a “paper” product, it is an extremely flexible and substrate-hugging sheet. Consequently, tests, specifically TAPPI T548 and ASTM C1028-07 are suitable and effective tests for determining the Coefficient of Friction of the novel non-skid drop cloth of the invention. 
     It is, therefore, an object of the invention to provide a protective cloth or pad that includes a resilient, non-skid surface to prevent movement of the cloth or pad on the surface upon which it is placed. 
     It is another object of the invention to provide a protective cloth or pad which is conformable to irregular surfaces such as stairs and remains in position once placed thereupon. 
     It is an additional object of the invention to provide a protective cloth or pad that has a resilient lower member having a grid of downward protruding, interconnected bumps. 
     It is a further object of the invention to provide a protective cloth or pad that utilizes materials wherein Van Der Walls forces help provide the desired frictional characteristics. 
     It is yet another object of the invention to provide a protective cloth or pad that utilizes hydrophobic thermoset resin plastic materials. 
     It is an additional object of this invention wherein the “bumps” are formed from hydrophobic materials. 
     It is a further object of the invention to provide a protective cloth or pad having a woven fabric upper member. 
     It is a still further object of the invention to provide a protective cloth or pad that, optionally, may contain an interposed impervious member. 
     It is an additional object of the invention to provide a protective cloth or pad having a Static Coefficient of Friction greater than approximately 0.75 measured in accordance with TAPPI T548 (Slide Angle method). 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Various objects, features, and attendant advantages of the present invention will become more fully appreciated as the same becomes better understood when considered in conjunction with the accompanying drawings, in which like reference characters designate the same or similar parts throughout the several views, and wherein: 
         FIG. 1  is a side, elevational, cross-sectional, schematic view of a portion of the non-skid protective cloth or pad in accordance with the invention; 
         FIG. 2  is a bottom plan view of the resilient layer of the non-skid protective cloth or pad of  FIG. 1 ; 
         FIG. 3  is a side elevational, cross-sectional, schematic view of the non-skid protective cloth or pad of  FIG. 1  but containing an interposed impervious layer; 
         FIG. 4  is a perspective, schematic view of a slide angle testing apparatus for performing Coefficient of Friction testing in accordance with the TAPPI T548 standard; 
         FIG. 5  is a table of results measured by testing samples of the non-skid drop cloth of the present invention using the apparatus of  FIG. 4  to perform a Coefficient of Friction test in accordance with the TAPPI T-548 standard; and 
         FIG. 6  is a table of Coefficient of Friction results measured by testing samples of the non-skid drop cloth of the present invention in accordance with the ASTM C-1028-07 standard. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The present invention provides non-skid protective cloth or pad for a variety of applications. 
     Referring first to  FIG. 1 , there is shown a side, elevational, cross-sectional, schematic view of a portion of the non-skid protective cloth or pad in accordance with the invention, generally at reference number  100 . 
     Non-skid protective cloth or pad  100  has two layers—a woven upper layer  102  and a lower, resilient layer  104 . Woven upper layer  102  is typically an absorbent, woven cotton material such as canvas or another canvas-like material. For purposes of disclosure, an 8-ounce material has been chosen. Canvas may be treated with a waterproofing material, if desired. Such a treatment, however, renders the upper woven layer  102  non-absorbent which may impair the function of upper woven layer  102  to absorb paint or other material spilled thereupon. It will, however, be recognized by those of skill in the art that other weight materials may be chosen depending upon the desired application in which non-skid protective cloth or pad  100  is to be utilized. It will further be recognized that woven materials other than cotton may be selected to meet a particular operating circumstance or environment. Consequently, the invention is not limited to the 8-ounce canvas chosen for purposes of disclosure. Rather the invention covers any suitable material and weight. 
     A lower, resilient layer  104  is bonded to woven upper layer  102 , typically by stitching  112 . It will be recognized that methods and/or materials other than stitching may be utilized to secure upper woven layer  102  to lower, resilient layer  104 . Some possible choices include, but are not limited to adhesive fastening, hook-and-loop fasteners, mechanical fasteners, etc. A “mechanical” fastening method (e.g., stitching, etc.) rather than a chemical, thermal fusing, or any other type of bonding is shown. However, it will be recognized that a non-mechanical method of fastening lower, resilient layer  104  to woven upper layer  102  may be desirable to meet a specific operating circumstance or environment. 
     Referring now also to  FIG. 2 , lower resilient layer  104  has a plurality of downward-projecting bumps  106   a ,  106   b . Bumps  106   a  are typically larger in circumference than bumps  106   b . As shown in  FIG. 1 , larger bumps  106   a  are shown having a greater height than smaller bumps  106   b . In alternate embodiments, larger and smaller bumps  106   a  and  106   b , respectively, may have a substantially identical height. In still other embodiments, smaller bumps  106   b  may have a height larger than larger bumps  106   a.    
     Bumps  106   a ,  106   b  are interconnected by resilient web segments  108 . An inter-bump space  110  remains between bumps. As seen in  FIG. 1 , inter-bump space is shown schematically to be between a larger bump  106   a  and a smaller bump  106   b . However, inter-bump space  110  may be between any two larger bumps  106   a  or between any two smaller bumps  106   b  as well as between larger bump  106   a  and smaller bump  106   b  as shown for purposes of disclosure. 
     Bumps  106   a ,  106   b  may be formed from of a foamed thermoset plastic resin. When the bumps  106   a ,  106   b  are compressed by an object or a person standing on non-skid protective cloth or pad  100 , the grip or friction on either wet or dry surfaces is exceptional. This gripping is caused by the compressed areas spreading under the load, and therefore having greater contact surface with the substrate and, consequently, producing higher Van Der Waals forces to keep the non-skid protective drop or pad stationary. 
     In operation, non-skid protective cloth or pad  100  is placed on a surface to be protected, not shown, resilient layer  104  towards the surface. Bumps  106   a ,  106   b  grip the surface, especially when compressed by the weight of a person, not shown, directly over a particular portion of non-skid protective cloth or pad  100 . 
     One exemplary use of non-skid protective cloth or pad  100  is to protect a surface from paint, varnish, stain, etc. The choice of material for upper woven layer  102  allows paint or other material to be at least partially absorbed by the layer. Canvas is a typical material selected for upper woven layer  102 . Unlike impervious drop cloths (i.e., thin plastic sheets), the partially absorbed paint is typically less prone to tracking by a person stepping in the spilled paint than is paint spilled on a non-absorbing cloth of the prior art. In addition, non-skid protective cloth or pad  100  may be laundered to remove soluble paint or other materials. 
     Non-skid protective cloth or pad  100  may also be utilized to protect a delicate surface from being scratched or marred. One environment where non-skid protective cloth or pad  100  is particularly useful is on a set of stairs. Once positioned, non-skid protective cloth or pad  100  remains in place, thereby providing a safe, stable surface on the stairs as workmen ascend and descend the stairs. It will be recognized that the choice of materials, weights, thicknesses, etc will determine the overall flexibility of non-skid protective cloth or pad  100  for applications such as stairs. 
     An example of the use of non-skid protective cloth or pad  100  as a protective pad, maintenance routines periodically require mechanics to walk on the upper surface of an airplane wing. The use of non-skid protective cloth or pad  100  on the wing not only protects the delicate wing surface but provides a much more secure surface upon which the mechanic may walk or stand. Even though the surface of the wing is typically curved, the novel construction of non-skid protective cloth or pad  100  greatly improves the security of the mechanic. 
     Another exemplary use of non-skid protective cloth or pad  100  is to protect delicate surfaces of boat decks in an environment where they frequently become wet and slippery. Non-skid protective cloth or pad  100  remains in place on the deck, even wet, and provides a non-slip upper surface (i.e., the upper surface of upper woven layer  102 ) upon which boat passengers may walk. Because non-skid protective cloth or pad  100  typically lacks an impermeable membrane, air may flow though non-skid protective cloth or pad  100 , thereby allowing the cloth and the surface therebelow to dry. 
     In an alternate embodiment, a third layer, typically an impermeable layer  114  may be interposed between woven upper layer  102  and resilient layer  104 . This is shown in  FIG. 3 . 
     To quantify the slip resistance of non-skid protective cloth or pad  100 , Coefficient of Friction Slide Angle Testing was performed by SGS North America, Consumer Testing Services, 291 Fairfield Avenue, Fairfield, N.J., USA. The results of the testing were reported in Test Report No. 3235547PP02R3 dated Sep. 9, 2013. Five samples of non-skid protective cloth or pad  100  were submitted and tested in accordance with the TAPPI T548 test procedures. 
     Referring now also to  FIG. 4  there is shown a perspective, schematic view of a slide angle testing apparatus for performing Coefficient of Friction Testing in accordance with the TAPPI T548 standard, generally at reference number  400 . 
     Tester  400  has a flat base portion  402  and an elevatable portion  404  hingedly attached to flat base portion  402  by a hinge  406 . 
     A protractor scale  408  is affixed to flat base portion  402  so as to measure the inclination of elevatable portion  404  relative to flat base portion  402 . An indicator  414  is attached to elevatable portion  404  to provide an exact indication on protractor scale  408 . 
     A clamp  410  is provided to selectively secure a sample of a first material for testing  416  against an upper surface of elevatable upper portion  404 . 
     A sample  412  of the second material being tested is placed on an upper surface of the sample of the first material  416 . 
     A typical test is begun with elevatable upper portion  404  in a lowered position flat against base portion  402 . In other words, elevatable upper portion is at a zero degree elevation. 
     A “smooth drive system” (i.e., a drive system that introduces minimum vibration, jerkiness, etc.), not shown, activated through shaft  418  is used to slowly elevate upper elevatable portion  404  until sample  412  slides along sample  416 . It important that the smooth drive system not impart vibration to the apparatus that could introduce inaccuracy into the test results. 
     Referring now also to  FIG. 5 , there are shown test results for tests of novel drop cloth  100  (i.e., non-skid protective cloth or pad), sample  412  sliding on a sample of laminate wood flooring (i.e., sample  416 ). 
     As may readily be seen, five specimens (i.e., samples) were tested in accordance with the TAPPI T548 test procedure. Column  430  shows the angle (i.e., the inclination of elevatable upper portion  404 ) at which sample  412  slides along sample  416 . 
     A Static Coefficient of Friction may readily be calculated from the side angle measured for a particular specimen. These Static Coefficient of Friction values are enumerated in column  432 . 
     Averages  436 ,  438  are calculated for slide angles and Static Coefficient of Friction, respectively. 
     It will be noted that testing was performed with a lab environmental temperature and humidity of 23° C. and 50% relative humidity, reference number  440 . Specimens were acclimated for 24 hours minimum prior to testing. 
     These test results showed an average slide angle of approximately 43 degrees and an average Static Coefficient of Friction of approximately 0.9 when non-skid protective cloth or pad  100  is tested on a laminate flooring sample. Laminate flooring was estimated to represent the most “slippery” surface upon which a painter&#39;s drop cloth might be utilized. 
     Samples of novel drop cloth  100  were also tested using a horizontal dynamometer pull tester in accordance with the ASTM C1028-07 test procedure. The results of this test are shown in  FIG. 6 . 
     As may readily be seen, twelve specimens (i.e., samples)  450  were tested in accordance with the ASTM C1028-07 specification. Column  452  shows the angle the measured Static Coefficient of Friction measured with dry samples while column  454  shoes the Static Coefficient of Friction measures with wet samples. 
     The average Static Coefficient of Friction for dry samples,  456 , was 0.814. Likewise, the average Coefficient of Static Friction for wet samples,  458 , was 0.589. Both average Coefficients  456  and  458  exceeded the Coefficient of Friction value of 0.5 as required in OSHA proposed rules for “Walking and Working Surfaces; Personal Protective Equipment (Fall Protection Systems)” as published in the Federal Register 68:23527-23568, Section 1910.22 General Requirements, Section 2 . Slip - resistance.    
     “A reasonable measure of slip-resistance is static coefficient of friction (COF). A COF of 0.5, which is based upon studies by the University of Michigan and reported in “Work Surface Friction: Definitions, Laboratory and Field Measurements, and a Comprehensive Bibliography,” is recommended as a guide to achieve proper slip-resistance. A COF of 0.5 is not intended to be an absolute standard value. A higher COF may be necessary for certain work tasks, such as carrying objects, pushing or pulling objects, or walking up or down ramps.” 
     As seen in Notes  462 , that testing was performed with a lab environmental temperature and humidity of 23° C. and 50% relative humidity. Specimens were acclimated for 24 hours minimum prior to testing. The Neolite Sled Weight was 56 pounds. 
     Since other modifications and changes varied to fit particular operating requirements and environments will be apparent to those skilled in the art, the invention is not considered limited to the example chosen for purposes of disclosure, and covers all changes and modifications which do not constitute departures from the true spirit and scope of this invention. 
     Having thus described the invention, what is desired to be protected by Letters Patent is presented in the subsequently appended claims.