Abstract:
Absorbent articles suitable for use as training pants or other hygiene products are provided. The absorbent articles include a chassis having a contiguous front section, a rear section, and a crotch section extending between the front section and the rear section. Edges of the front section connect to edges of the rear section to define a waist opening. The chassis includes a substrate layer having pairs of film sections attached to the front section and the rear section. Each film section is spaced apart from one another and are stretchable in at least a direction along the waist opening. Products according to the invention may provide any of several benefits, including at least one of improved fit, comfort, manufacturability, and visual appearance.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to absorbent articles such as diapers, training pants, and the like. More specifically, the invention relates to absorbent articles having integral side panels that are stretchable in at least one direction. 
       BACKGROUND OF THE INVENTION 
       [0002]    Absorbent articles such as disposable diapers, training pants, and the like are known for their major function of absorbing and containing body exudates. Such articles are thus intended to prevent the soiling, wetting, or other contamination of clothing or other articles, such as bedding, that come in contact with the wearer. In the case of disposable training pants, they typically include a chassis with a liquid permeable topsheet, a liquid impermeable backsheet, and an absorbent core positioned between the topsheet and the backsheet. Side panels are sometimes attached to the chassis for fitting the training pant about the wearer&#39;s waist so the training pant may be pulled up or down like traditional underwear. 
         [0003]    While many developments have been made in the art of absorbent articles, there remains a need for further improvements in terms of at least one of improved fit, comfort, manufacturability, and visual appearance. 
       SUMMARY OF THE INVENTION 
       [0004]    In one aspect, the invention provides an absorbent article having a chassis with a contiguous front section, a contiguous rear section, and a crotch section extending between the front section and the rear section. Edges of the front section are connected to edges of the rear section to define a waist opening. The chassis includes a substrate layer having pairs of film sections attached to the front section and the rear section. Each film section is spaced apart from one another and is stretchable in at least a direction along the waist opening. 
         [0005]    In another aspect of the invention, a method of applying a stretchable layer of an absorbent article is provided. The method includes the step of advancing a substrate of the absorbent article in a machine direction. A layer of adhesive is applied to the substrate in a slot coating corresponding to a shape of the stretchable layer. The stretchable layer is then oriented such that it is stretchable in the machine direction. The stretchable layer is attached by means of the adhesive. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0006]    The invention is best understood from the following detailed description when read in connection with the accompanying drawings, with like elements having the same reference numerals. This emphasizes that according to common practice, the various features of the drawings are not drawn to scale. On the contrary, the dimensions of the various features are arbitrarily expanded or reduced for clarity. Included in the drawings are the following figures: 
           [0007]      FIG. 1  is a top plan view of an absorbent article according to an embodiment of the invention. 
           [0008]      FIG. 2  is a cross-sectional view of the absorbent article shown in  FIG. 1  according to exemplary embodiments of the invention; 
           [0009]      FIG. 3  is a top plan view of layers of an absorbent article according to one embodiment of the invention; and 
           [0010]      FIG. 4  is a top plan view of layers of an absorbent article according to a second embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0011]    Referring generally to the drawings ( FIGS. 1-4 ), in accordance with an exemplary embodiment, the invention provides an absorbent article  100 ,  200  having a chassis that includes a contiguous front section  110 ,  210 , a rear section  120 ,  220 , and a crotch section  130 ,  230  extending between the front section  110 ,  210  and the rear section  120 ,  220 . Edges  15   a ,  15   b  of the front section  110 ,  210  are connected to edges  16   a ,  16   b  of the rear section  120 ,  220  to define a waist opening. The chassis includes a substrate layer  109  having pairs of film sections  40   a - d  attached to the front section and the rear section. Each film section  40   a - d  is spaced apart from one another and is stretchable in at least one direction, such as the machine direction MD, along the waist opening. 
         [0012]    In another exemplary embodiment, a method for method of applying a stretchable layer  40  of an absorbent article  100 ,  200  is provided. The method includes the step of advancing a substrate  109  of the absorbent article  100 ,  200  in a machine direction MD. A layer of adhesive  1  is applied to the substrate  109  in a slot coating corresponding to a shape of the stretchable layer  40 . The stretchable layer  40  is oriented such that it is stretchable in the machine direction MD and the stretchable layer  40  is attached to the substrate  109  by means of the adhesive  1 . 
         [0013]    Referring now to the drawing in detail,  FIG. 1  depicts a plan view of an absorbent article  100  according to one exemplary embodiment of the present invention. Absorbent article  100  includes a chassis having a contiguous front section  110 , a rear section  120 , and a crotch section  130  extending between the front section  110  and the rear section  120 . The chassis has a substantially hour-glass shape such that edges  15   a ,  15   b  of the front section  101  to connect to edges  16   a ,  16   b  of the rear section  120  to define a waist opening. The edges  15   a - b ,  16   a - b  of the front section  110  and rear section  120  may be joined in any suitable manner such as by adhesive bonding, heat sealing, ultrasonic bonding, stitching or the like. 
         [0014]    The front section  110  is configured to be positioned against the anterior or front end of a wearer and the rear section  120  is configured to be positioned on the posterior or back end of a wearer. When worn by an individual standing upright, the crotch portion  130  of chassis forms the lowest point on absorbent article  100 . 
         [0015]    As shown in  FIG. 1  and later described, the chassis includes a substrate layer  109  having pairs of stretchable film sections  40   a - d  integrally attached to the front section  110  and the rear section  120 . Each film section  40   a - d  is spaced apart from one another and is stretchable in at least direction along the waist opening. For example, film sections  40   a - d  are stretchable in at least the machine direction MD in which absorbent article  100  is manufactured. 
         [0016]    Referring now to  FIG. 2 , a cross-sectional view of the absorbent article  100  shown in  FIG. 1  illustrated. According to an exemplary embodiment, absorbent article  100  includes an absorbent core  150  interposed between a liquid permeable topsheet  101  and a substrate layer  109 . In use, the absorbent core  150  is configured to receive liquid through the topsheet  101 . When the absorbent article  100  is in place, the liquid permeable topsheet  101  and waist elastic portions  102   a - b  are arranged to face toward the body of the user (i.e. against the skin of the wearer) and the substrate layer  109  is arranged facing away from the wearer. 
         [0017]    In order to enable liquid to quickly and efficiently pass through the topsheet  101  and into the absorbent core  50  for trapping therein, the topsheet  101  is preferably liquid permeable. In particular, the topsheet  101  may be selected from a variety of textile-like films and fabrics. Suitable fabrics include non-woven materials that are pervious to liquid, soft and pliable. Preferred non-woven materials include spun-bonded polypropylene, spunbonded polyethylene, and thermally bonded webs of staple fibers, preferably polypropylene shape or sheath/core bi-component fibers having a core of polyester or polypropylene and a sheath of polyethylene. 
         [0018]    As seen with respect to the embodiment of the absorbent article  100  shown in  FIG. 1 , the absorbent core  150  which is interposed between the topsheet  101  and substrate layer  109  may be of any shape, but is typically a rectangular member that is centered in the chassis and extends from a portion of the front section  120  to a portion of the rear section  120 . The absorbent core  150  may be made of any suitable absorbent material, as well as combinations of different types of absorbent materials. For example, the absorbent core  138  may be formed of a mixture of pulp fluff and superabsorbent polymer (SAP) wrapped in a liquid permeable tissue wrap  104   a - b . Examples of SAP include polyacrylamides, polyvinyl alcohol, polyacrylates, various grafted starches, and the like. The super absorbent materials can be in various geometric forms, such as various shaped particles, fibers, foams, and layers. The amount of each absorbent material and SAP/fluff ratio depends on factors including the size of the article  100 . 
         [0019]    According to an exemplary embodiment, the chassis includes an acquisition layer  103  interposed between the topsheet  101  and absorbent core  150  to rapidly take up fluid through the topsheet  101  and then release it into the absorbent core  150 . Acquisition layer  103  remains substantially dry even after liquid has penetrated the acquisition layer  103 . Thus, acquisition layer  103  provides an insulating layer between the absorbent core  150  and topsheet  101  to prevent contact between a wet absorbent core  150  and the wearer&#39;s skin. 
         [0020]    The acquisition layer  103  is generally composed of resilient fibrous webs that provide a small absorbent volume to rapidly take up liquids and then direct it to the absorbent core  106 . This allows adequate time for super absorbent materials in the core  150  to absorb the liquid. The thickness of the acquisition layer  103  is preferrably thin to provide the small absorbent volume. 
         [0021]    A liquid impermeable barrier layer  105  is interposed between the absorbent core  150  and substrate layer  109 . Barrier layer  105  is arranged facing away from the wearer (i.e. away from the skin of the wearer) and is preferably formed from a hydrophobic polymeric film to prevent liquid from seeping through absorbent core  150  and wetting a wearer&#39;s clothing. Materials for forming the barrier layer  105  may include polyethylene films, polypropylene films, co-extruded films (polyethylene and ethylene vinyl acetate), co-polymer films (polyethylene/polypropylene), and polylaminates (polypropylene nonwoven and polyethylene film). In an exemplary embodiment, barrier layer  105  may be joined to tissue  104   b  of absorbent core  150  in any suitable manner such as hot melt adhesive  1 . 
         [0022]    According to the present invention as shown in  FIG. 2 , stretch panels are integrally formed on absorbent article  100  by attaching stretchable, non-porous film sections  40   a ,  40   c  to substrate layer  109 . Each film section  40   a ,  40   c  is attached directly to substrate layer  109  by a layer of adhesive  1 . Adhesive  1  may be applied to substrate layer  109  in various patterns. For example, adhesive  1  may be applied in a spiral, comb, or omega pattern. Preferably, adhesive  1  is applied in a slot coating such that the dimensions of the adhesive  1  correspond to the shape of the film section  40   a ,  40   c . Thus, when film section  40   a ,  40   c  is adhered to substrate layer  109 , the stretch panels form a smooth appearance. In another exemplary embodiment, film section  40   a ,  40   c  may be joined to substrate layer  109  in any suitable manner such as by heat sealing, ultrasonic bonding, stitching or the like. 
         [0023]    In an exemplary embodiment, film section  40   a ,  40   c  are stretched prior to adhering the film section  40   a ,  40   c  on substrate layer  109 . Thus, after film sections  40   a ,  40   c  have been attached, stretch panels “retract” due to tension from the film sections  40   a ,  40   c . Each film section  40   a ,  40   c  is spaced apart from one another such that when edges  15   a - b ,  16   a - b  ( FIG. 1 ) of the front section  110  and rear section  120  are connected, stretch panels are located near the hips of wearer. In this embodiment, middle portions of the front section  110  and rear section  120  are substantially non-stretchable, thereby providing a substantially smooth surface in which indicia may be printed or attached. In an exemplary embodiment, cloth-like carrier layers  106  may be attached above film sections  40   a ,  40   c  to provide additional padding and form the stretch panel laminate. A portion of substrate layer  109  may be folded over and adhered to carrier layer  106  and/or waist elastic portion  102   a  to complete the finished absorbent article  100  product. 
         [0024]    According to an exemplary embodiment, film sections  40   a ,  40   c  may be made of any thermoplastic elastomer (TPE). Such resins/copolymers may include, for example, styrene-ethylene/butylene-styrene (SEBS) or styrene-ethylene/propylene-styrene (SEPS) that may be used to create films that are extrudable at higher temperatures then become elastic at an ambient temperature. The stretchable film sections may be breathable or non-breathable depending on the desired properties of the absorbent article  100 . For example, a stretchable film made of a “breathable” microporous polyethylene to provided added comfort and passage of air through the stretch panel laminate. 
         [0025]    Referring now to  FIG. 3 , the substrate layer  109  of absorbent article  100  shown in  FIGS. 1 and 2  is illustrated. As described above, film sections  40   a - d  are integrally attached to substrate layer  9  by adhesive, thereby forming the stretch panel of absorbent article  100 . In an exemplary embodiment, film sections  40   a - d  are stretched in the machine direction MD (i.e., direction of manufacture) prior to attachment on substrate layer  109 . For example, film sections  40   a - d  may be stretched by a series of rollers and cut prior to being adhered to substrate layer  109  with spaces between film sections  40   a - d . As described above, portion  60   a ,  60   b  in which film sections  40   a - d  are not attached may be substantially non-stretchable such that indicia may be printed or attached to substrate layer  109 . 
         [0026]    In an exemplary embodiment, film sections  40   a - d  may be stretched in a direction perpendicular to the machine direction MD such that film sections  40   a - d  are stretchable in at least two directions. In this embodiment, film sections  40   a - d  may be stretched in both the cross-direction CD and machine direction MD, to provide and absorbent article  100  with integral panels that are stretchable in at least two directions. According to another embodiment, film sections  40   a - d  may be oriented with respect to substrate layer  109  such that the film sections  40   a - d  are stretchable in the machine direction MD. For example, rolls of substrate layer  109  and/or stretchable film layer  40   a - d  may be oriented parallel to each other using a machine direction orienter such that as substrate layer  109  is running in the machine direction MD, the stretchable layer may be stretched and attached to the substrate layer  109  in the same direction. 
         [0027]    In an exemplary embodiment, the substrate layer  109  may be a non-elastic material may be formed from a single layer of non-woven material, and may exhibit substantially no elastic/stretch properties (i.e. inelastic). The substrate layer  109  is optionally formed from a laminated sheet of a non-woven material and film (with the non-woven side positioned as the outermost layer). One particularly suitable material is a spunbond-meltblow-spunbond (SMS) web. The spunbond layer is optionally made of polypropylene fibers. Such composites provide the dual advantages of liquid barrier properties of film along with a soft, outer fabric texture. 
         [0028]    The substrate layer  109  can also be made of other suitable cloth-like materials, e.g., spun-bond or thermal-bond non-woven web made of either polypropylene, polyethylene, polyester, bi-component fibers (polyethylene/polypropylene or polyethylene/polyester), or any combinations of these fibers. Various multiple layer configurations or fiber denier variations may be used. Another example includes hydro-entangled non-woven webs, which may contain some cotton and/or rayon fibers blended in with thermal-plastic fibers. Cellulose fibers can also be blended in at small percentages to reduce cost. Still, other materials for forming the substrate layer  109  may include polypropylene films, co-extruded films (polyethylene and ethylene vinyl acetate), co-polymer films (polyethylene/polypropylene), and polylaminates (polypropylene nonwoven and polyethylene film). In yet another embodiment, the substrate layer  109  is optionally selected from a variety of textile-like films and fabrics. 
         [0029]    Referring now to  FIG. 4 , according to an exemplary embodiment, absorbent article  200 , includes a chassis in which stretchable layer  41   a ,  41   b  is attached to substrate layer  109  across the entire front section  210  and rear section  220 . Thus, the entire waist portion of absorbent article  200  is stretchable in at least one direction. For example, the entire waist portion of absorbent article  200  is stretchable in the machine direction MD, cross-direction CD, or both the machine direction MD and cross-direction CD. 
         [0030]    Although the present invention has been particularly described in conjunction with specific embodiments, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art. It is therefore contemplated that the appended claims will embrace any such alternatives, modifications, and variations as falling within the true scope and spirit of the present invention.