TECHNICAL FIELD 
       [0001]    The present invention relates generally to fluid retaining mop structures, and more particularly to a mop head incorporating fluid retaining strand elements of contoured, tubular construction incorporating an arrangement of elongate surface channel depressions extending at least partially along the length of such strand elements interposed between raised profile protrusions. A process for forming the mop head is also provided. 
       BACKGROUND OF THE INVENTION 
       [0002]    Mop heads incorporating tubular strand elements of so-called “edgeless” construction are known. One such construction, which is marketed by Contec Inc. of Spartanburg, S.C., is formed from a skein of circular knit material of tubular construction which is formed on a winding apparatus using a pair of support bars which rotate relative to one another. The skein structure is formed from a single continuous tube of the knit material. Upon removal from the winding apparatus, the skein thus has an interior and two ends formed by the reverse folds in the knit tube where it has been passed around the winder bars. The skein structure is thereafter inserted into a relatively narrow width containment sleeve which is seamed to the interior of the skein structure at a substantially central location to contain the tubular elements in the wound structure. Seams are also applied at slightly inboard positions relative to the folded over ends of the skein structure so as to avoid undue spreading of the individual folded over elements. The mop head so formed is thereafter attached to a handle at the central containment sleeve. Importantly, the prior mop heads formed in this manner have utilized a circular knit, tubular structure in the material forming the skein having a substantially uniform flat exterior surface. 
       SUMMARY OF THE INVENTION 
       [0003]    The present invention provides advantages and alternatives over the prior art by utilizing a relatively narrow diameter, knit tubular material to form the strands of a mop head substantially in the same manner as described above but wherein the tubular material incorporates an arrangement of elongate depressed channels and raised profile segments or ridges extending along its surface in the length direction rather than using the flat surface structure of the prior constructions. This construction has surprisingly been found to increase the overall fluid retaining or sorbency capacity of the mop relative to the prior flat surface construction even while lowering the overall mass of the mop head. That is, more fluid may be retained even though less fluid retaining material is utilized thus providing a substantial improvement over the prior known construction. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS  
         [0004]    The accompanying drawings which are incorporated in and which constitute a part of this specification illustrate potentially preferred embodiments and practices in accordance with the present invention and, together the general description of the invention given above and the detailed description set form below, serve to explain the principles of the invention wherein: 
           [0005]      FIG. 1  is a simplified illustration of a circular knitting machine as will be well known to those of skill in the art for use in forming the absorptive string elements of a mop head according to the present invention; 
           [0006]      FIG. 2  illustrates a mop head according to the present invention in attached relation to a handle structure; 
           [0007]      FIG. 3  is an elevation plan view of the mop head in  FIG. 2 ; 
           [0008]      FIG. 4  is a cross-sectional side view of the mop head in  FIG. 3 . 
           [0009]      FIG. 5  illustrates an exemplary cross-section of an individual strand taken through line  5 - 5  in  FIG. 1 . 
       
    
    
       [0010]    While the invention has been illustrated and generally described above and will hereinafter be described in connection with certain potentially preferred embodiments and procedures, it is to be understood that in no event is the invention to be limited to such illustrated and described embodiments and procedures. On the contrary, it is intended that the present invention shall extend to all alternatives and modifications as may embrace the broad principles of this invention within the true spirit and scope thereof. 
       DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0011]    Reference will now be made to the various drawings wherein to the extent possible, like reference numerals are utilized to designate like components throughout the various views. In  FIG. 1 , there is illustrated a circular knitting machine  10  such as will be well known to those of skill in the art. By way of example only, and not limitation, one knitting machine  10  which has been identified as suitable for practice of the present invention is a model ST3AH/ZA high speed, single feed, circular knit machine having a cylinder size of 1.5 inches in diameter and 48 needle slots available manufactured by Lamb Knitting Machine Corporation having a place of business in Chicopee, Mass. USA. 
         [0012]    According to one contemplated practice, in operation a pair of yarns  12 ,  12 A is delivered from spools  13 ,  13 A to the knitting machine  10  for formation of a tubular knit structure  14 . The yarn  12  is preferably a 150 denier singles textured polyester having either an “S” or “Z” twist construction. The yarn  12 A is preferably a 150 denier two ply textured polyester wherein one ply has an “S” twist and the other ply has a “Z” twist. Thus, the two yarn system incorporates yarn orientations with a combination of opposing twists. This balance in twist permits the knit structure to avoid undue curling when subjected to laundering operations. Of course, the particular yarn system selected may be varied as desired by the user. 
         [0013]    The tubular knit structure  14  which is formed according to the potentially preferred practice of the invention includes an arrangement of elongate channel depressions  20  running along the length of the tubular knit structure  14  ( FIG. 5 ). The depressions  20  are disposed between raised profile surface protrusions  24  across the surface of the tubular knit structure  14  such that an undulating or corrugated surface profile is provided wherein the elongate channels and surface protrusions extend in alternating substantially parallel relation. 
         [0014]    According to a potentially preferred practice, the illustrated arrangement of channel depressions  20  and raised profile protrusions  24  is achieved by using a modified needle arrangement in the knitting equipment to create a space between courses formed during the knitting process. According to one exemplary practice, the circular knit machine as described above is modified to incorporate a needle arrangement with four needles in and two needles out in an arrangement which is repeated eight times around the circumference of the cylinder. This produces a profiled surface with eight cooperating channel depressions  20  and eight raised profile protrusions  24 . Of course this number may be greater or lower as desired but will preferably be at least four and will more preferably be about 6 or greater. According to one potentially preferred practice the machinery is set up to produce a tubular knit structure with fourteen courses per inch (relaxed state) and a weight of about 6.1 grams per linear yard (relaxed state). The resulting construction is a modified jersey knit utilizing thirty-two active needles for knitting. 
         [0015]    It is contemplated that the tubular knit structure as described will form the fluid retaining strands of a mop head  30  attached to a handle  40  to form a mop  50  as illustrated in  FIG. 2 . As best illustrated through simultaneous reference to  FIGS. 2-4 , the mop head  30  is formed from a skein of the tubular knit material  14 . As previously indicated, such a structure may be formed by winding an extended length of the tubular knit material multiple times around a pair of spaced-apart bars and then removing the formed structure from those spaced-apart bars. As illustrated, the resultant skein structure has an arrangement of folds  32  at either end of the skein structure. As will be appreciated, the folds  32  are formed at the location where the tubular knit material is wrapped around the opposing bars during the winding operation. Of course, it is also contemplated that a similar structure may be formed by hand coiling or other techniques as may be desired. Moreover, while it may be desirable to use a single long piece of tubular knit material  14  folded upon itself multiple times to form the mop head, it is also contemplated that two or more shorter lengths may be used if desired. Thus, it is to be understood that by the term “skein” is meant any structure in which one or more lengths of elongate material are folded upon themselves such that the folds define an edge boundary with discrete strand elements extending away from the edge boundary. 
         [0016]    According to the illustrated and potentially preferred practice, the skein structure forming the mop head  30  is fitted into a containment sleeve element  34  of fabric or the like which is then seamed in place so as to hold the strands of tubular knit material  14  in adjacent relation to one another at a central location. Moreover, the ends of the tubular knit material where the winding begins and concludes are also held in hidden relation beneath the containment sleeve element  34 . Finally, strips of material  36  are seamed in transverse relation to the strands of tubular knit material  14  at positions inboard of the folds  32  so as to maintain a desired adjacent relation of the strand elements at each end of the mop head  30 . The mop head  30  may thereafter be washed and dried prior to attachment to the handle  40 . 
         [0017]    As previously indicated, the adjustment of the circular knitting machine  10  to produce the tubular knit material  14  with interspersed elongate channel depressions  20  and raised profile protrusions  24  yields substantially improved moisture retention capacity even when lower weights of material are utilized. This moisture retention capacity is referred to as “sorbent capacity” and may be made up of moisture retention resulting from absorption and/or adsorption at the strands of tubular knit material. In this regard, it is contemplated that the benefits of the present invention will be applicable to both hydrophilic as well as hydrophobic materials of construction although polyester which is hydrophobic may be particularly preferred. 
         [0018]    In order to evaluate the relative performance of a mop head formed according to the present invention, exemplary mop heads formed with fluid retaining strands having elongate channel depressions and raised profile protrusions were weighed in a dry state and were thereafter immersed in water until fully saturated and then weighed in a wet state once dripping had substantially ceased. The contoured surface mop heads were formed according to the potentially preferred practice as described above on a 1.5 inch diameter circular knitting head with an arrangement of four needles in and two needles out repeated eight times around the circumference. Mop heads of similar construction but incorporating flat surface tubular strands of knit material formed on the same knitting head but with all needles in were tested according to the same procedure. Each of the structures was also tested to measure sorbency in a wet state wherein the wet mop was immersed after wringing excess moisture from the mop head following initial saturation. The results are set forth in Table I below: 
         [0000]    
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                   
                 Dry mop sorbent 
                 Wet mop sorbent 
                   
                   
               
               
                   
                 Dry mop weight 
                 capacity 
                 capacity 
                   
                 Wet mop weight 
               
             
          
           
               
                   
                 In 
                 In 
                 Intrinsic 
                 Extrinsic 
                 Intrinsic 
                 Extrinsic 
                 % 
                 In 
                 In 
               
               
                   
                 grams 
                 ounces 
                 (mL/g) 
                 mL/mop 
                 (mL/g) 
                 (mL/mop) 
                 wringability 
                 grams 
                 ounces 
               
               
                   
                   
               
             
          
           
               
                 Flat 1 
                 433 
                 15.3 
                 2.83 
                 1225 
                 0.92 
                 400 
                 32.7% 
                 1258 
                 44.4 
               
               
                 Flat 2 
                 431 
                 15.2 
                 2.67 
                 1150 
                 0.93 
                 400 
                 34.8% 
                 1181 
                 41.7 
               
               
                 Averages 
                 432 
                 15.2 
                 2.75 
                 1188 
                 0.93 
                 400 
                 33.7% 
                 1220 
                 43.0 
               
               
                 Contoured 1 
                 399 
                 14.1 
                 4.39 
                 1750 
                 2.01 
                 800 
                 45.7% 
                 1349 
                 47.6 
               
               
                 Contoured 2 
                 399 
                 14.1 
                 4.26 
                 1700 
                 2.13 
                 850 
                 50.0% 
                 1249 
                 44.1 
               
               
                 Contoured 3 
                 402 
                 14.2 
                 4.35 
                 1750 
                 1.99 
                 800 
                 45.7% 
                 1352 
                 47.7 
               
               
                 Contoured 4 
                 399 
                 14.1 
                 4.26 
                 1700 
                 1.88 
                 750 
                 44.1% 
                 1349 
                 47.6 
               
               
                 Contoured 5 
                 400 
                 14.1 
                 4.25 
                 1700 
                 2.13 
                 850 
                 50.0% 
                 1250 
                 44.1 
               
               
                 Contoured 6 
                 401 
                 14.1 
                 4.49 
                 1800 
                 2.12 
                 850 
                 47.2% 
                 1351 
                 47.7 
               
               
                 Contoured 7 
                 399 
                 14.1 
                 4.39 
                 1750 
                 2.13 
                 850 
                 48.6% 
                 1299 
                 45.8 
               
               
                 Averages 
                 400 
                 14.1 
                 4.34 
                 1736 
                 2.05 
                 821 
                 47.3% 
                 1314 
                 46.4 
               
               
                   
               
               
                 Flat 1 and 2 are the prior structures and contoured 1-6 are specimens of the present invention. 
               
             
          
         
       
     
         [0019]    As can be seen, the mop structure of the present invention exhibited substantially greater intrinsic sorbent capacity in both the wet and dry states relative the prior structure using flat tube fluid containment strands. 
         [0020]    While the present invention has been illustrated and described in relation to certain exemplary and potentially preferred embodiments and practices, it is to be understood that such embodiments and practices are illustrative only and that the present invention in no event to be limited thereto. Rather, it is contemplated the modifications and variations will no doubt occur to those of skill in the art upon reading the above description and/or through practice of the invention. It is therefore contemplated and intended that the present invention shall extend to all such modifications and variations which may incorporate the broad concepts of the present invention within the full spirit and scope thereof.
An edgeless mop utilizing a relatively narrow diameter, knit tubular material to form the strands of a mop head wherein the tubular material incorporates an arrangement of elongate depressed channels and raised profile segments extending along its surface in the length direction. This construction increases the overall fluid retaining or sorbency capacity of the mop even while lowering the overall mass of the mop head.