Patent Publication Number: US-2005137556-A1

Title: Sanitary absorbent article having a reinforced structure

Description:
CROSS REFERENCE TO RELATED APPLICATIONS  
      This application claims priority to Application No. 60/526,793 filed on Dec. 4, 2003. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates to sanitary absorbent articles, such as disposable sanitary napkins, which feature a reinforced structure.  
     BACKGROUND OF THE INVENTION  
      In general, sanitary absorbent articles are large-scale commercially manufactured articles used to absorb and retain bodily exudates. Such articles, which are convenient since they are economical yet disposable, include sanitary napkins, infant diapers, adult incontinence pads, and the like.  
      The technology surrounding sanitary absorbent articles, and particularly feminine sanitary napkins, has undergone several advances over the past few decades. One such advance was the addition of a flap projecting laterally from each longitudinal side edge of the article when the article is in a flattened state. Such flaps may be comprised of integral extensions of a material from which the article is formed or, alternatively, they may simply be comprised of additional material added to the article after its formation.  
      During use, the flaps are folded over the edges of the wearer&#39;s undergarment. Thus, they more firmly secure the article to the undergarment, stabilize the article within the undergarment, provide an increased absorptive area for bodily exudates, and help prevent the undergarment from becoming soiled in part by protecting the side edges of the wearer&#39;s undergarment. The flap concept has been well received in the marketplace and, as a result, articles featuring flaps of various configurations and conformations are currently available to the consumer.  
      Conventional wisdom on the part of both designers and consumers has to date dictated that the flaps on absorbent articles should be maximized at their area of juncture with the main body of the article in order to provide a greater area of protection against exudate leakage over the side of the article. Hence, a very common flap configuration is an isosceles (i.e. bilaterally symmetrical) trapezoidal-shaped flap having its base adjoined with the longitudinal side edge of the main body of the article and projecting in tapering fashion away therefrom to the top of the trapezoid. The size and shape of the flaps, however, may vary from article to article.  
      Sanitary napkins featuring flaps characterized by a width (dimension measured along the longitudinal axis of the sanitary napkin) that increases in a direction away from the main body of the napkin have also been proposed. This flap design offers a number of advantages, an important one being to securely retain the sanitary napkin to the undergarment of the wearer. Such enhanced retention is desirable because it stabilizes the sanitary napkin against the body of the wearer and thus reduces the likelihood of failure events.  
      One of the difficulties associated with the use of sanitary napkins employing flaps, however, is that the wearer, once the sanitary napkin has been used, will not detach the flaps from the undergarment before lifting away the sanitary napkin&#39;s main body. The tendency is to simply pull the main body while the flaps remain attached to the undergarment. This manipulation creates stress levels on the sanitary napkin at the area of juncture main body/flap and may cause the flaps to tear and separate from the main body. This is undesirable since the wearer must then remove the separated flap(s) in a subsequent operation that may cause annoyance. Moreover, the tearing of the flaps may expose the user&#39;s undergarment to bodily exudates contained in the sanitary napkin thereby soiling the same.  
      Considering this background, it clearly appears that there is a need in the industry to develop a feminine sanitary napkin which can better resist flap tearing.  
     SUMMARY OF THE INVENTION  
      Under a first broad aspect, the present invention provides a sanitary napkin adapted to be worn in the crotch portion of an undergarment. The sanitary napkin comprises a main body, at least one flap and a flap reinforcing element. The main body includes a fluid-permeable layer facing toward the wearer when the sanitary napkin is placed in the undergarment, a liquid-impervious layer, an absorbent system for absorbing liquid, a pair of opposite longitudinal side edges and a pair of opposite transverse side edges. The absorbent system is located between the fluid-permeable layer and the liquid-impervious layer. The flap is attached to the main body at an area of juncture, and has two sides and a distal end that is remote from the area of juncture. The flap and the main body together define a continuous contour, wherein at least a portion of the continuous contour includes a peripheral seal for joining the fluid-permeable layer and the liquid-impervious layer together. The continuous contour comprises a first segment and a second segment. The first segment extends along one of the longitudinal side edges from the area of juncture toward one of the transverse side edges and the second segment extends along one of the sides of the flap from the area of juncture toward the distal end. The flap reinforcing element spans across the area of juncture thereby bridging the main body and the flap. The flap reinforcing element has an edge portion that is co-extensive with the first segment and the second segment of the continuous contour, and a boundary that is internal to the peripheral seal. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      A detailed description of preferred embodiments of the present invention is provided herein below with reference to the following drawings, in which:  
       FIG. 1  is a top plan view of a first non-limiting example of implementation of a sanitary napkin of the present invention;  
       FIG. 2   a  is a cross-sectional view taken along line  2   a - 2   a  of  FIG. 1 ;  
       FIG. 2   b  is a cross-sectional view of a sanitary napkin constructed in accordance with a first variant of the invention;  
       FIG. 2   c  is a cross-sectional view of a sanitary napkin constructed in accordance with a second variant of the invention;  
       FIG. 2   d  is a cross-sectional view of a sanitary napkin constructed in accordance with a third variant of the invention;  
       FIG. 3  is a top plan view of a sanitary napkin constructed in accordance with a fourth variant of the invention;  
       FIG. 4  is a cross-sectional view taken along line  4 - 4  of  FIG. 3 ;  
       FIG. 5  is a top plan view of a sanitary napkin constructed in accordance with a fifth variant of the invention;  
       FIG. 6  is a cross-sectional view of a sanitary napkin constructed in accordance with a sixth variant of the invention; and  
       FIG. 7  is a cross-sectional view of a sanitary napkin constructed in accordance with a seventh variant of the invention. 
    
    
      In the drawings, preferred embodiments of the invention are illustrated by way of examples. It is to be expressly understood that the description and the drawings are only for the purpose of illustration and as an aid to understanding. They are not intended to be a definition of the limits of the invention.  
     DETAILED DESCRIPTION  
      With reference to  FIG. 1 , there is shown a non-limiting example of implementation of a sanitary absorbent article, a disposable sanitary napkin  20 . The sanitary napkin  20  comprises a main body  22  having generally opposing longitudinal side edges  24 ,  26 , and an imaginary longitudinal centerline  28  running down the center of the sanitary napkin  20 , generally equidistant from the longitudinal side edges  24 ,  26 .  
      The main body  22  also has two generally opposing transverse side edges  30 ,  32 . Projecting laterally from each of the longitudinal side edges  24 ,  26  of the main body  22  are flaps  34 ,  36 . The flaps  34 ,  36  are generally of the shape of an isosceles (i.e. bilaterally symmetrical) trapezoid, with the shorter of the two parallel sides thereof adjoining the longitudinal side edges  24 ,  26  of the main body  22  of the napkin  20 . An imaginary transverse centerline  38  runs across the sanitary napkin  20  and intersects imaginary longitudinal centerline  28 .  
      As shown in  FIG. 2   a , the napkin  20  is a laminate structure. The main body  22  includes a fluid-permeable cover layer  40 , which will face the body of a wearer when the sanitary napkin  20  is in use, a liquid-impervious barrier layer  48 , which will face the environment (i.e. away from the body of the wearer, and in almost all cases the wearer&#39;s undergarment) when the sanitary napkin  20  is in use and an absorbent system  42  located between the fluid-permeable cover layer  40  and the liquid-impervious barrier layer  48 . The absorbent system  42  may have a single layer or multiple layers. In the example of implementation depicted in the drawings, absorbent system  42  includes a multi-layer structure. More specifically, the absorbent system  42  has a first layer, called a “transfer layer”  44  immediately underneath the fluid-permeable cover layer  40  and a second layer called an “absorbent layer”  46  between the transfer layer  44  and the liquid-impervious barrier layer  48 .  
      The fluid-permeable cover layer  40  and the liquid-impervious barrier layer  48  are sealed together along their peripheral edges (including the flaps  34 ,  36 ) to form a peripheral seal  50 , containing the absorbent system  42 . The peripheral seal  50  can be realized by using any means commonly known in the art such as by gluing, crimping, pressure and/or heat-sealing, ultrasonics, and the like. Although peripheral seal  50  is shown as being continuous, the present invention also contemplates embodiments where the peripheral seal  50  is intermittent and therefore does not necessarily completely enclose the absorbent system  42 . Thus, a variety of seal configurations are within the scope of this invention.  
      Each of the above layers will now be described in greater detail.  
      Fluid-Permeable Cover Layer  
      With reference to  FIGS. 1 and 2   a , the fluid-permeable cover layer  40  is the top layer of the sanitary napkin  20 . The purpose of the fluid-permeable cover layer  40  is to provide an interface that would normally contact the body of the wearer when the sanitary napkin  20  is in use. The fluid-permeable cover layer  40  is porous to liquids since its main function is to capture as quickly as possible a discharge of bodily exudate and transfer it to the absorbent system  42  underneath.  
      Under one specific example of implementation, the fluid-permeable cover layer  40  is formed from an apertured thermoplastic film. Such films are common in the art. Because of the high porosity of such films, they accomplish the function of quickly transferring body exudate to the inner layers (i.e. the absorbent system  42 ) of the napkin  20 .  
      The fluid-permeable cover layer  40  can also be made of fibrous materials, such as non-woven fibrous materials. The fluid-permeable cover layer  40  may be composed of only one type of fiber, such as polyester, or may be composed of bicomponent or conjugate fibers having a low melting point component and a high melting point component. Bicomponent fibers may be made up of a polyester core and a polyethylene sheath. The use of appropriate bicomponent materials results in a fusible non-woven fabric. Using a fusible fabric increases the ease with which the fluid-permeable cover layer  40  may be mounted to the barrier layer  48  at the peripheral seal  50 .  
      The fibers may be selected from a variety of natural and synthetic materials such as nylon, polyester, rayon (in combination with other fibers), cotton acrylic fiber and the like, and combinations thereof. It will be evident to the person skilled in the art that a wide variety of other types of non-woven fabric materials can also be used.  
      Transfer Layer  
      Adjacent to the fluid-permeable cover layer  40  on its inner side and bonded thereto is the optional fluid transfer layer  44 , that may form part of the absorbent system  42 . The transfer layer  44  provides the means of receiving body fluid from the fluid-permeable cover layer  40  and holding it until the highly-dense absorbent layer  46  has an opportunity to absorb it.  
      The transfer layer  44  is, preferably, more dense than than the fluid-permeable cover layer  40  and has a larger proportion of smaller pores than does the latter. These attributes allow the transfer layer  44  to contain body fluid and hold it away from the outer side of the fluid-permeable cover layer  40 , thereby preventing the fluid from re-wetting the fluid-permeable cover layer  40  and its surface. However, the transfer layer  44  is preferably not so dense as to prevent the passage of the fluid through the transfer layer  44  and into the underlying absorbent layer  46 .  
      The transfer layer  44  may be composed of fibrous materials such as wood pulp, polyester, rayon, flexible foam, or the like, or combinations thereof. The transfer layer  44  may also comprise thermoplastic fibers for the purpose of stabilizing the layer and maintaining its structural integrity. The transfer layer  44  may be treated with surfactant on one or both of its sides in order to increase its wettability. However, the transfer layer  44  is generally relatively hydrophilic and may not require additional treatment. The transfer layer  44  is preferably bonded on both sides to the adjacent layers, i.e. the fluid-permeable cover layer  40  and the absorbent layer  46 .  
      Absorbent Layer  
      Immediately adjacent to and bonded to the transfer layer  44  is the absorbent layer  46 ; the latter also forming part of the absorbent system  42 . The absorbent system  42  may comprise a single layer structure or may comprise a multi-layer structure.  
      The absorbent layer  46  is a highly dense layer having a fine porosity. It has a large liquid-holding capacity and it is extremely retentive. Preferably, the absorbent layer  46  comprises a pulp fluff material and may optionally include other absorbent materials or non-absorbent materials such as conjugate fibers, fusible fibers, binders, sphagnum moss, superabsorbents, and the like and combinations thereof.  
      Liquid-Impervious Barrier Layer  
      Underlying the absorbent system  42  is a liquid-impervious barrier layer  48  which comprises liquid-impervious film material such as to prevent liquid that is entrapped in the absorbent layer  46  from egressing the sanitary napkin  20  and staining the wearer&#39;s undergarment. The liquid-impervious barrier layer  48  can be made of polymeric film, such as polyethylene or a polyethylene/ethylvinyl acetate (EVA), which are both inexpensive and readily available. The polymeric film is capable of fully blocking the passage of liquid or gas that may emanate from the absorbent system  42 . In a variant, breathable films may be used that allow passage of gases while blocking liquid.  
      Flaps  
      Preferably, the flaps  34 ,  36  are comprised of integral continuous extensions of the fluid-permeable cover layer  40  and the liquid-impervious barrier layer  48 . Thus, the flaps  34 ,  36  are dual layer structures, the upper layer being a continuous extension of the fluid-permeable cover layer  40  while the bottom layer is a continuous extension of the liquid-impervious barrier layer  48 . It should be specifically understood, however, that flaps having a single layer structure also remain within the scope of the present invention.  FIG. 2   a  further shows that flaps  34 ,  36  do not contain the absorbent system  42  therein. However, in an alternative embodiment not shown in the drawings, the absorbent system may extend into the flaps or the flaps may be provided with separate absorbent layers.  
      Since both flaps  34  and  36  are identical, only flap  34  will be described herein.  
      As depicted in  FIGS. 1 and 2   a , flap  34  extends from the main body  22  starting at an area of juncture  52 . Flap  34  is preferably an extension of the fluid pervious layer and the liquid impervious layer, as mentioned above, but in an alternative embodiment, flap  34  can also be a separate structure that is attached to the main body  22  at the area of juncture  52 . The flap  34  has a proximal end  54  that is adjacent the area of juncture  52 , a distal end  56  that is remote from the area of juncture  52 , as well as a pair of sides  58 ,  60  which extend between the proximal and distal ends. Preferably, the flaps  34 ,  36  do not longitudinally extend the entire length of the sanitary napkin  20 .  
      The flaps  34 ,  36  and main body  22  together delineate a continuous contour  62  which includes at least two contiguous segments, namely a first segment  64  that is defined by a portion of longitudinal side edge  24 , and a second segment  66  that is defined by a portion of side  60 . First segment  64 , more specifically, extends from the area of juncture  52  toward transverse side edge  32  while second segment  66  extends from the area of juncture  52  toward the distal end  56  of the flap. It should be noted that contiguous segments such as those described above exist at each side of each flaps  34 ,  36 .  
      The sanitary napkin  20  further includes flap reinforcing elements. Various embodiments of the flap reinforcing elements will be described herein below with respect to  FIGS. 1-7 .  
       FIGS. 1 and 2   a  show that sanitary napkin  20  comprises a pair of flap reinforcing elements  68 .  FIG. 1  is a top plan view in which various layers of the napkin are transparently depicted in order to show the flap reinforcing elements  68  that, in the embodiment depicted in  FIG. 1 , are attached below barrier layer  48 . In  FIG. 1 , the reinforcing elements  68  are shown in cross-hatching. As shown, both flap reinforcing elements  68  extend in a direction that is substantially parallel to imaginary longitudinal centerline  28 . In addition, each flap reinforcing element  68  spans across the area of juncture  52 , thereby bridging the main body  22  and a respective flap. By “bridging”, it is meant that each flap reinforcing element  68  respectively extends from a flap  34  or  36  into main body  22 . Each flap reinforcing element  68 , by bridging the main body  22  and its respective flap  34  or  36 , reinforce the sanitary napkin  20  along the area of juncture  52  such that it is better able to resist the stress levels that occur when a user grasps a used napkin and attempts to remove it from an undergarment without having previously detached the flaps.  
      As is also shown in  FIG. 1 , each flap reinforcing element  68  is generally shaped such that a portion of an outer edge  70  of the flap reinforcing element  68  is co-extensive with the continuous contour  62  and, more particularly, with the first and second segments  64 ,  66 . By “co-extensive”, it is meant that the portion of the outer edge  70  of each flap reinforcing element  68  shares a common boundary with the continuous contour  62  defined by flaps  34 ,  36  and main body  22 .  
      Although  FIGS. 1 and 2   a  show that each flap reinforcing element  68  fully extends in a longitudinal direction between both transverse side edges  30  and  32 , it should be specifically understood that embodiments in which a flap reinforcing element does not fully extend between both transverse side edges  30 ,  32  remain within the scope of the present invention.  
      In the specific embodiment shown in  FIG. 1 , each flap reinforcing element  68  includes two boundaries  71  and  69  that are shown in dotted lines in  FIG. 1 . The boundary  71  is located in an area which is intermediate the distal ends  56  of flaps  34 ,  36  and their respective proximal ends  54 , and the boundary  69  is located between the two areas of juncture  52  of the two flaps  34  and  36 . Both boundaries  71  and  69  have portions that are internal to the peripheral seal  50 . In an alternative embodiment, the side edges  70  of the flap reinforcing elements  68  are co-extensive with the longitudinal sides of the napkin  20  and the distal end  56  of flaps  34 ,  36 . In such an embodiment, the flap reinforcing elements  68  would have only one boundary  69  that is internal to the peripheral seal  50 .  
      Although  FIG. 2   a  depicts a specific embodiment in which each flap reinforcing element  68  is fastened to the liquid-impervious barrier layer  48 , it should be expressly understood that flap reinforcing elements that are secured to the sanitary napkin  20  in other locations remain within the scope of the invention.  FIG. 2   b , for example, depicts an embodiment in which the flap reinforcing elements  68  are fastened to the fluid-permeable cover layer  40 . Alternatively, the flap reinforcing elements  68  may be disposed within the sanitary napkin  20  and therefore hidden to view.  FIG. 2   c , for example, shows flap reinforcing elements  68  that are disposed between the absorbent system  42  and the fluid-permeable cover layer  40 . Similarly,  FIG. 2   d  shows flap reinforcing elements  68  that are disposed between the absorbent system  42  and the liquid-impervious layer  48 .  
      It could also be advantageous, in an embodiment where the flap reinforcing element  68  is disposed between the fluid-permeable cover layer  40  and the absorbent system  42 , for the flap reinforcing element  68  to possesses fluid management attributes. For example, the flap reinforcing element  68  may be more dense than the fluid-permeable cover layer  40  and have a larger proportion of smaller pores than does the latter. In addition to reinforcing the sanitary napkin, the flap reinforcing element  68  can therefore also act as a transfer layer. However, the flap reinforcing element  68  must still provide sufficient reinforcement to the flaps  34 ,  36 .  
      In order to manufacture the sanitary napkins  20  shown in  FIGS. 1 and 2   a - 2   d , the flap reinforcing elements  68  can be pre-fastened to either the liquid-impervious barrier layer  48  or the fluid permeable cover layer  40  in positions that will cause the flap reinforcing elements  68  to span across the areas of juncture  52  when the sanitary napkin  20  is complete. As such, during production of the sanitary napkins  20 , the layers of the sanitary napkins can be handled in the usual manner, without having to alter the equipment for incorporating the flap reinforcing elements  68  into the production process.  
       FIGS. 1 and 2   a  to  2   d  all depict embodiments in which the flap reinforcing elements extend in a direction that is substantially parallel with the imaginary longitudinal centerline  28 . Other realizations wherein the flap reinforcing element extends in a direction that is essentially parallel to the imaginary transverse centerline  38 , are equally possible.  FIGS. 3 and 4  depict such an embodiment. As shown in  FIG. 3 , the sanitary napkin  20  includes a single flap reinforcing element  72  (shown in cross-hatching) which extends between the distal ends  56  of both flaps  34 ,  36 . As such, flap reinforcing element  72  spans across the areas of juncture  52  associated with the flaps  34 ,  36  thereby bridging the main body  22  and the flaps  34 ,  36 .  FIG. 3  further shows that flap reinforcing element  72  is shaped such that it features edge portions  73 ,  75  that are respectively co-extensive with the distal ends  56  of flaps  34 ,  36  and co-extensive with the first and second segments  64 ,  66  of the continuous contour  62 . In addition, flap reinforcing element  72  includes boundaries  77  and  79  that include portions that are internal to the peripheral seal  50 .  
      Although not shown in  FIGS. 3 and 4 , the flap reinforcing element  72  can be positioned between the fluid permeable layer  40  and the fluid impervious layer  48 . It could be advantageous, in the embodiment where the flap reinforcing element  72  is disposed transversely between the fluid-permeable cover layer  40  and the liquid-impervious barrier layer  48 , for the flap reinforcing element  72  to possesses fluid management attributes, since the flap reinforcing element  72  covers the central area of the main body  22 , which is typically the fluid impact zone.  
      In alternative embodiments where the transversely extending flap reinforcing element  72  is disposed between the liquid-impervious barrier layer  48  and the absorbent system  42  and wherein the former is made of breathable material (i.e., permeable to gases/vapors but impermeable to liquids), it could be advantageous for the flap reinforcing element  72  to comprise a material that is impermeable to both liquids and gases/vapors. Thus, enhanced protection against leaking is offered in an area that is coincident with bodily exudate discharge.  
      Although  FIG. 3  depicts a single flap reinforcing element  72  extending in a direction that is essentially parallel to the imaginary transverse centerline  38 , it should be specifically understood that any number of flap reinforcing elements extending in this same direction nonetheless remain within the scope of the present invention.  FIG. 5 , for example, shows a sanitary napkin having two flap reinforcing elements  76 ,  78 . Each of the flap reinforcing elements  76 ,  78 , however, respectively extends between the distal ends of both flaps  34 ,  36 , thereby spanning across both areas of juncture  52 . Although FIGS.  3  to  5  show transversely extending flap reinforcing elements  72 ,  76 ,  78  that are fastened on the liquid-impervious barrier layer  48 , it should be understood that transversely extending flap reinforcing elements that are secured to the sanitary napkin  20  in other locations remains within the scope of the present invention.  
      The flap reinforcing elements, such as flap reinforcing elements  68 ,  72 ,  76  and  78  described above, may comprise a polymeric material, such as a polyolefin or polyester, or alternatively, may comprise a fibrous or cellulosic material. Preferably, the flap reinforcing elements  68 ,  72 ,  76  and  78  have a thickness in the range of 7×10 −4  inches to 1.25×10 −3  inches and have tensile strengths that are sufficient to cause the areas of juncture  52  to resist tearing when subjected to tensile forces typically applied by a user when attempting to remove the napkin from an undergarment without having previously detached the flaps.  
      Each of the above embodiments describe flap reinforcing elements that include a single layer. It should be expressly understood, however, that multi-layered flap reinforcing elements are also encompassed by the present invention. For example, multiple plies of material may be combined together to form a multi-layer structure, or alternatively, a single piece of material can be folded in order to form a multi-layer structure.  
      In the examples of implementation depicted in  FIGS. 6 and 7 , the flap reinforcing elements  74  and  74 ′ are formed by folding an existing layer of the sanitary napkin  20  into multiple layers, in order to provide an area of increased strength. In the example of implementation shown in  FIG. 6 , the flap reinforcing layers  74  are each formed by folding the liquid-impervious barrier layer  48  along two longitudinally oriented fold lines such that the flap reinforcing elements  74  are three layers thick. The layers can be bound together via the use of adhesive, ultrasonic bonding, and the like. The flap reinforcing elements  74  are positioned such that they span across respective areas of juncture  52 , thereby bridging the main body  22  and a respective flap. In addition, the flap reinforcing elements  74  include a first boundary  80  and a second boundary  82 . Since the flap reinforcing element  74  is the portion of the liquid-impervious barrier layer that is three layers thick, the boundaries  80  and  82  of the flap reinforcing element are located where the three layers begin and where the three layers end. A top plan view of the sanitary napkin  20  shown in  FIG. 6  would look the same as the top plan view of the sanitary napkin  20  shown in  FIG. 1 , wherein the cross-hatched area represents the three layers of liquid impervious barrier layer. As such, boundary  80  would correspond to boundary  71  and boundary  82  would correspond to boundary  69 . Both boundaries  80  and  82  include portions that are internal to the peripheral seal  50 . It should also be understood that in the case where the flap reinforcing element is two layers thick or more than three layers thick, the boundaries of the flap reinforcing element are located where the multiple layers begin and where the multiple layers end.  
      Although the flap reinforcing element  74  is made from the liquid-impervious barrier layer  48 , it should be expressly understood that flap reinforcing elements that are made by folding other layers of the sanitary napkin  20  are also possible. As shown in  FIG. 7 , for example, the flap reinforcing element  74 ′ is formed by folding the fluid-permeable cover layer  40 . Although the flap reinforcing element  74  and  74 ′ shown in  FIGS. 6 and 7  extend in a direction that is substantially parallel to the imaginary longitudinal centerline  28 , it should be expressly understood that a flap reinforcing element formed of a fold that extends in a direction that is substantially parallel to the imaginary transverse centerline  38  also remains within the scope of the present invention.  
      Although various embodiments have been illustrated, this was for the purpose of describing, but not limiting, the invention. Various modifications will become apparent to those skilled in the art and are within the scope of this invention, which is defined more particularly by the attached claims.