Patent Publication Number: US-2012023693-A1

Title: Integral Dual Functionality Cleaning Pads

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of application Ser. No. 12/480,109, filed Jun. 8, 2009. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to floor cleaning pads and more particularly to floor cleaning pads having a textured surface for cleaning a target surface. 
     BACKGROUND OF THE INVENTION 
     Cleaning pads are well known in the art. Such pads are used for cleaning a target surface, such as a floor or other hard surface. Floors commonly cleaned with a pad include linoleum, tile, wood, etc. 
     For convenience, the cleaning pad may be removably attached to a cleaning implement. The cleaning implement may have an elongate handle for grasping by the user. The handle may be typically attached to a head by universal joint. Alternatively the handle and head may be in fixed relationship, as often occurs with a loop handle. The cleaning pad may be removably attached to the bottom of the head, for movement relative to the target surface during cleaning. Attachment may be accomplished using one or more grippers. Suitable grippers may be made according to commonly assigned U.S. Pat. Nos. 6,305,046; 6,484,346; and/or 6,651,290. Alternatively the pad may be removably adhesively attached or attached using hook and loop fasteners. Suitable cleaning implements include the Swiffer® Sweeper, Swiffer® WetJet® and Swiffer® SweeperVac® sold by the instant assignee. 
     Such cleaning pads may also be used with water, or in other cleaning solution to solubilize debris on the floor. The pads may be wetted and/or cleaning fluid may be distributed onto the floor from a reservoir. One suitable implement for cleaning with a pad and distributing cleaning fluid from a replaceable reservoir includes the Swiffer® WetJet® implement sold by the instant assignee. Such an implement may be made according to commonly assigned U.S. Pat. No. 6,386,392. Alternatively, a suitable pre-wetted cleaning pad includes the Swiffer® Sweeper Wet Cloths sold by the instant assignee and made according to commonly assigned U.S. Pat. No. 6,716,805. 
     The cleaning pads retain the dual functionality of transmitting cleaning solution to/from the pad and scrubbing debris or stains which may be difficult to remove from the floor. However, this dual functionality is not optimally met by a single surface of the cleaning pad. A surface suitable for transmitting cleaning fluid therethrough is not optimized for scrubbing debris and vice versa. 
     One solution to this problem is to provide two different materials, each having a surface optimized for the task of transmitting liquids therethrough or the task of scrubbing debris. However, this solution raises even more problems. Having two materials for the sheet increases inventory and assembly costs. Assembly may not properly occur, leading to scrap. Even if assembly is proper, the extra step of assembling the two materials as part of the production of the cleaning pad may slow the production, again increasing cost. 
     Thus, the efforts to make a better cleaning pad continue. One such effort is found in the cleaning pad of the present invention. 
     SUMMARY OF THE INVENTION 
     The invention comprise a cleaning pad for attachment to the head of a cleaning implement. The pad comprises a backsheet and a facing sheet joined in face-to-face relationship with an absorbent core therebetween. The facing sheet comprises an integral sheet having a first region with apertures therethrough, and a second region having a plurality of protrusions extending outwardly therefrom and away from the core. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a top plan view of a cleaning pad according to the present invention with the cleaning surface facing upwardly, shown partially in cutaway. 
         FIG. 2  is a vertical sectional view of the pad of  FIG. 1 , taken along line  2 - 2 . 
         FIG. 3  is a schematic perspective view of an apparatus suitable for making the sheet of the present invention. 
         FIG. 4  is a line profile plot representing an instantaneous sectional view of the facing sheet of the cleaning pad of  FIG. 2 . 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to  FIGS. 1 and 2 , a cleaning pad  20  according to the present invention may comprise a plurality of layers joined in face-to-face relationship to define an XY plane and Z-direction orthogonal thereto. The layers may comprise a facing layer  21  according to the present invention, an absorbent core  24 , and a backsheet  22 . Optionally, the backsheet  22  may have adhesive attachments on the outwardly facing surface. 
     The center of the cleaning pad  20  is defined at the junction of a centrally-disposed longitudinal axis L and a centrally disposed transverse axis T. Longitudinal axis L and transverse axis T define a two-dimensional plane of the cleaning pad, which, in the embodiment shown is associated with the machine direction (MD) and cross machine direction (CD), respectively as are commonly known in the art. 
     The backsheet  22  may be any liquid impervious sheet flexible, yet capable of imparting sufficient strength to the pad. One suitable backsheet  22  may be made of a laminate of spunbond/meltblown/spunbond fibers, as is known in the art. 
     The optional core  24  may be any layer capable of holding fluid and optionally delivering fluid. Fluid may be transmitted from the surface being cleaned, through the facing layer  21  to the core  24  or may be transmitted from the core  24  to the surface to be cleaned. The core  24  may further comprise absorbent gelling material as is known in the art, to increase its capacity. A suitable pad  20  may be made with a core  24  generally according to the teachings of commonly assigned U.S. Pat. Nos. 5,960,508; 6,003,191; 6,101,661 and/or 6,766,552. If desired, an optional secondary topsheet  27  may be included to improve fluid transmission and strength of the facing sheet  21 . 
     The facing layer has a first region  12  comprising a plurality of apertures, and a second region  14  comprising a plurality of raised, out-of-plane deformations that can be protrusions  31 . 
     The two regions  12 ,  14  are differentiated by the kind of topographical features disposed in each. The facing sheet  21  is the component of the cleaning pad  20  which contacts and cleans the target surface, such as a floor, in use. The facing sheet  21  is integral. By integral it is meant the facing sheet  21 , or other desired component of the cleaning pad  20 , is formed from a single raw material and is not made by joining two separate components together. 
     In particular, apertures  28  are disposed in, and may extend through, first region(s)  12  of the facing layer  21  may be sufficiently large (e.g., at least about 1 to 2 mm 2  each) to permit relatively viscous fluids, to flow through the facing layer  21  and into absorbent core  24  and less than 8 to 9 mm 2  to minimize leakage. First region(s)  12 , may be disposed generally centrally to cleaning pad  20 , and the second region  14  may be disposed outwardly of the first region  12 , or vice versa with the second region  14  centrally disposed and the first region  12  outboard thereof. In another embodiment, the first region  12  and second region  14  may overlap, to provide a region having both apertures  28  and out-of-plane protrusions  31 . 
     The embodiment illustrated in  FIG. 1  has the structural feature that protrusions  31  extend from the peripheral area of the cleaning pad in the Z-direction, while the apertures  28  are centrally disposed. This arrangement provides the benefit that applied force, compressively transmitted by the user through the handle of the cleaning implement tends to be centrally applied to the head of the cleaning implement. By having Z-direction deformations disposed away from the handle in the XY plane, the compressive force is more uniformly distributed in the XY plane. This relatively more uniform force distribution is believed to result in a more uniform compressive stress across the head of the cleaning implement when used in conjunction with the cleaning pad  20  of  FIG. 1 . This improved stress distribution is believed, in turn, to yield improved cleaning of the target surface and more complete usage of the cleaning pad  20 . 
     Protrusions  31  may be disposed in second region  14  of facing layer  21 . In general, by “out-of-plane” is meant extending in the “Z”-direction, as indicated by  FIG. 2 . In  FIG. 2  protrusions  31  are shown in exaggerated proportion, although there are not believed to be particular dimensional limitations. The only design considerations with respect to the dimensions of protrusions  31  are those related to the desired cleaning task. It may be that for particular facing layers  21  the height (Z-direction) of protrusions  31  can be uniform; in other embodiments the height can vary, such as by increasing with greater distance from longitudinal centerline L. The protrusions  31  may extend about 0.5 to about 4 millimeter, and about 1 to about 3 millimeters in the Z-direction. In one embodiment, protrusions  31  are disposed generally outboard of first region  12 , as shown in  FIG. 1 . 
     As shown in  FIGS. 1 and 2 , protrusions  31  can comprise raised ridges of a pre-defined length that is much shorter than the length of the cleaning pad, measured along the longitudinal centerline, for example. In one embodiment as shown in  FIG. 1 , protrusions  31  are disposed in a regular pattern of protrusions  31  that form a pattern of diamond-shapes, each diamond shape being comprised of a plurality of protrusions  31 . In this manner, the protrusions  31  may contribute to scrubbing capability. In general, the individual protrusions  31  can have a length, measured along their longitudinal orientation, of between 1% and 50% of the length of the cleaning pad, measured along the longitudinal axis. The individual protrusions  31  may have a spacing in the XY plane such that there is not an unbroken path from any portion of the first region  12  to either of the longitudinal side edges of cleaning pad  20 . 
     The facing layer  21  can comprise nonwoven materials as are known in the art for facing layers on disposable absorbent articles and cleaning pads  20 . Absorbent core  24  and backsheet  22  may likewise comprise absorbent materials, and film materials, respectively, as are well known in the art. An optional secondary facing layer can be used as a distribution layer to distribute fluid in the XY directions. 
     The dual cleaning benefit of the present invention is in part due to apertures  28  and protrusions  31  that form discrete regions of facing layer  21 . Apertures  28  provide for relatively unimpeded fluid flow of cleaning fluid and even viscous fluid. Raised, protrusions  31  may act as a plurality of individual fluid barriers, each effective in retarding any free fluid flow that may have a tendency to run off the facing layer  21  when cleaning pad  20  is used, without becoming a total block of fluid distribution to outboard portions of the cleaning pad  20 . In addition protrusions  31  may function as resilient textured wipers, to help clean debris from the target surface. 
     As shown in  FIG. 2 , apertures  28  permit fluid communication through the facing layer  21 . Typically, inner surface of the facing layer  21  is in contact with absorbent core  24  to allow efficient fluid flow into the core  24 . Apertures  28 , and discrete raised, protrusions  31  may also add elastic extensibility to facing layer  21 . 
     Although all the raised, protrusions  31  are shown as being aligned longitudinally in the MD, the raised, protrusions  31  could be oriented in any desired configuration. Other patterns of apertures  28  and protrusions  31  are within the scope of the invention, including, for example, a discrete region in the center of the cleaning pad  20  having apertures, the discrete region not extending to any of the peripheral edges. Also, apertures  28  and protrusions  31  could be in a striped pattern with the stripes generally transversely, longitudinally, diagonally oriented or aligned in a combination thereof. The first region  12  may comprise from about 30 to about 90 percent, or about 40 to about 80 percent of the width of the cleaning pad  20 . 
       FIG. 3  shows an apparatus for making facing layer  21  of the present invention that is suitable for use with cleaning pad  20 . Facing layer  21  may formed from a generally planar, two dimensional nonwoven precursor web  200  on apparatus  100 , the apparatus may be oriented for continuous web processing with respect to a machine direction (MD) and a cross machine direction (CD) as is commonly known in the art of nonwoven webs. Precursor web  200  has formed therein in predetermined regions a plurality of melt-weakened portions  115  prior to entering nip  116 . Melt-weakened portions  115  are formed in predetermined regions of web  200  by thermal point calendaring in the predetermined regions, the predetermined regions corresponding to first region(s)  12  of facing layer  21 , that is, the region where apertures  28  are ultimately desired. Each melt-weakened portion  115  of the predetermined region may be generally elongated and/or oriented in the MD. Upon stretching in the CD in the portion of the apparatus  100  corresponding to the region  113 , the melt-weakened portions  115  rupture to form apertures  28 . The melt-weakened portions  115  may be limited to the central region of web  200 , that is, corresponding to the central first region  12  of cleaning pad  20  in  FIG. 1 . 
     The apparatus  100  may comprise a pair of rolls  102  and  104 , each rotating about parallel axes A, and is similar in many respects to the apparatuses described in commonly assigned U.S. Pat. Nos. 5,916,661; 5,628,097 and 5,518,801 issued to Chappell et al. and U.S. 2004/0127875 published in the name of Hammons et al. By combining both into one apparatus to form both apertures  28  and protrusions  31  in one facing layer  21 , the cleaning pad  20  of the present invention provides for significant cleaning and fluid handling benefits over prior art cleaning pads. Further, such facing layer  21  provides these benefits in with an integral facing layer  21 , further providing for convenient and inexpensive manufacture. 
     The apparatus  100  shown in  FIG. 3  may comprise a roll  102  having a plurality of circumferentially-extending ridges  106  separated by grooves  108 , as disclosed in the above-mentioned patents and as well known in the art of “ring-rolling.” A second, intermeshing roll  104  comprises a first region  113  having essentially matching roll  102  and having ridges  106  separated by grooves  108 . The intermeshing ridges  106  and grooves  108  of rolls  102  and  104  incrementally stretch precursor web  200  to form apertures  28  as disclosed in U.S. Pat. Nos. 5,916,661 and 5,628,097. Of course, precursor web  200  has melt-weakened regions  115  formed therein prior to precursor web  200  entering the nip  116  of apparatus  100 . 
     In addition to region  113 , roll  104  may have two regions  111  comprising ridges with teeth  110 , the toothed ridges separated by grooves  112 . Ridges  106  of roll  102  intermesh with the grooves  112  of roll  104  to form the protrusions  31  of second region(s)  14 . A pitch of about 0.7 to 13 millimeters, and particularly about 1.5 millimeters may be utilized for the second region  14 . A pitch of about 0.7 to 13 millimeters, and particularly about 2.5 millimeters may be utilized for the first region  12 . The rolls  102 ,  103  may have an engagement of about 0.5 to 26 millimeters, independent of pitch. 
     Facing layer  21  has a first region  12  defined on both sides of facing layer  21  by having a plurality of spaced apart apertures  28 . A second region  14  is defined by a plurality of spaced-apart protrusions  31  which may be integral extensions of the fibers of the precursor web  200 . 
     One advantage of the apparatus  100  described above is that the facing layer  21  can be produced in-line with other production equipment on a manufacturing line for producing such articles. For example, an apparatus  100  such as disclosed above, can be made as a unit operation for an existing manufacturing line. As a unit operation, such apparatus  100  can be modular, so that it can be easily changed out. When used as part of a manufacturing line for cleaning pads  20 , the constituent rolls  102 ,  104  need not be much wider than the product itself, thereby providing for relatively easy installation and removal. Various patterns of first regions  12  and second regions  14  can therefore be implemented with a minimum interruption. 
       FIG. 4  shows a line profile plot of an exemplary cleaning pad  20  according to the present invention. In this embodiment, first region  12  is disposed generally central with respect to the cleaning pad  20 . The second region  14  is disposed outboard of first region  12 , in a region extending from first region  12  to an area adjacent longitudinal edges of the cleaning pad  20 . 
     The protrusions  31  in the second regions  14  function to scrub or loosen debris from the target surface. The apertures  28  in first region  12  then function to absorb liquid cleaner deposited on the target surface and retain debris on the cleaning pad  20 . The pad  20  and debris can then be discarded. 
     The dimensions and other values disclosed herein are not to be understood as being strictly limited to the exact numerical values recited. Instead, unless otherwise specified, each such value is intended to mean both the recited value and a functionally equivalent range surrounding that value. For example, a dimension disclosed as “40 mm” is intended to mean “about 40 mm.”Every document cited herein, including any cross referenced or related patent or application, is hereby incorporated herein by reference in its entirety unless expressly excluded or otherwise limited. The citation of any document is not an admission that it is prior art with respect to any invention disclosed or claimed herein or that it alone, or in any combination with any other reference or references, teaches, suggests or discloses any such invention. Further, to the extent that any meaning or definition of a term in this document conflicts with any meaning or definition of the same term in a document incorporated by reference, the meaning or definition assigned to that term in this document shall govern. 
     While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.