Patent Application
20080082073
The present invention discloses an hourglass shaped absorbent article having an integrated chassis with selective elastomeric zones. The invention can be better understood with the help of accompanying figures.
In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art will appreciate that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as a critical, required, or essential features or elements of any or all the claims.
The term “disposable absorbent article” as mentioned herein refers to articles that absorb and contain body discharges. The articles are discarded after a first use and are not intended to be used more than once. The invention is described below with reference to hourglass shaped diapers that are placed close to the body and wrapped over so as to form an underwear-like structure. However it will be understood that the invention is also applicable to other types of absorbent articles such as adult incontinent briefs, children training pants and the like.
The portions of the article can be described using the following terms. If the article is spread out flat on a table with the body-touching portion facing up, then the visible surface is referred to as the ‘top of the article’. The surface touching the table is referred to as the ‘bottom of the article’. The near-rectangular portion in the middle of the article is referred to as the ‘crotch section’. The larger outstretched portion is referred to as the ‘rear of the article’, and more particularly the ‘bottom-rear’ portion of the article covering the buttocks of the wearer. The portion of the article at the other end of the ‘crotch section’ is referred to as the ‘front portion’ of the article. The ‘bottom-front’ portion forms the facing portion of the article.
The invention will now be explained with reference to the accompanying figures. Although reference herein is made to baby diapers, it will be appreciated that the invention is also applicable to all such products that have a waist region, such as training pants, adult incontinence articles and the like. While the present invention is described by reference to diapers that have an hourglass configuration, the invention is also applicable to other kinds of configurations wherein a diaper fit is attained by changing the configuration at the waist, for example pant-type diapers and the like.
A liquid permeable body liner 55 forms a top sheet of absorbent article 10. A liquid impervious sheet 60 forms the bottom sheet of absorbent article 10. Interposed between these sheets is an absorbent core 50 that functions to absorb body fluids. Rear portion 40 spans outwards and has elastomeric members called elastomeric ears 80 at respective left and right edges of absorbent article 10. Elastomeric ears 80 are attached to rear portion 40 at regions 85 using attachment means including adhesives, ultrasonic welding and the like. Elastomeric ears 80 have fasteners 90 attached to their edges. These fasteners are intended to engage coupling member 75 placed on the left and right edges of front portion 30 of absorbent article 10.
Absorbent article 10 is fastened to the wearer such that when article 10 is worn, crotch portion 20 is positioned between the legs of the wearer. Front portion 30 covers the area of the stomach below the navel while rear portion 40 covers the hips of the wearer. Ears 80 are pulled over from behind such that they cover the side hips using fasteners 90 that are joined to coupling member 75 on the front portion of absorbent article 10. Absorbent article 10 is further provided with elastic members 65 at crotch portion 20, front portion 30 and rear portion 40. Fasteners 90 and coupling members 75 ensure that absorbent article 10 may be tightened or loosened depending on the wearer's convenience.
Ear-like projections 80 are formed of elastomeric material and project outwards from the center of absorbent article 10. Since the elastomeric ears are separately cut and then joined to the rest of the article, the manufacturing process becomes complicated. Furthermore the need for maintaining additional inventory also arises.
The present invention provides an integrated chassis that has elastomeric properties in certain zones.
Integrated chassis 210 comprises a back sheet, an absorbent core and a top sheet that are placed and joined to form an integrated structure. The back sheet is made from a single sheet of composite material that has elastomeric characteristics. The elastomeric characteristics are allowed to remain active in certain zones such as ear portions A1 and A2. The remainder portions of the garment may be treated by heat and/or chemicals to suppress the elastomeric characteristics. The top sheet can be made of non-elastic material. The top sheet is disposed only to cover crotch portion 240 i.e. excluding the areas A1 and A2. This ensures that when the elastomeric ears A1 and A2 are pulled when the article is worn, the elasticity of the ears is not restricted by the non-elastic members.
In an alternative embodiment, the top sheet may be made from a composite material having selective zones with elastomeric characteristics. In this case, both the top sheet and the back sheet may have ear projections that can be kept elastomeric.
However, in both of the embodiments described above, care has to be taken that the material chosen has the desired properties expected of the particular layer. For example, the top sheet has to be soft to the body, permeable and preferably made from a breathable fabric. The back sheet needs to be liquid impermeable, breathable and non slippery.
In yet another embodiment of the invention as shown in
It will be understood that the elasticity of areas B1 and B2 may differ from that of the elastic ears. This selective elastic stretchability may be achieved by treating various zones with varying amounts of thermal, sonic or chemical treatment.
The materials used for individual components may be chosen from a wide variety of known suitable materials. The terms “elastic” and “stretchable” include any material which can be stretched, and which tends to return to its original shape when relaxed. Suitable polymers for manufacturing individual components include, without limitation, block copolymers of polystyrene, polyisoprene and polybutadiene; copolymers of ethylene, natural rubbers and urethanes; and combinations of the foregoing. Other suitable polymers include copolymers of ethylene, including without limitation ethylene vinyl acetate, ethylene methyl acrylate, ethylene ethyl acrylate, ethylene acrylic acid, stretchable ethylene-propylene copolymers, and combinations thereof. As a general rule, the elastomeric material used in the present invention is stretchable in at least one direction. Preferably, the elastomeric material is stretchable in two directions. When the elastomeric material is stretchable in a single direction, the stretch direction of the elastomeric material will be oriented so as to provide elastomeric forces which tend to pull the front and rear portions of the article towards one another such that the article is maintained at about the waist of a wearer. The elastomeric material can comprise materials such as a stretch-bonded-laminate (SBL) material, a neck-bonded-laminate (NBL) material, an elastomeric film, an elastomeric foam material, or the like. For example, suitable meltblown elastomeric fibrous webs are described in U.S. Pat. No. 4,663,220, issued May 5, 1987, to T. Wisneski et al., the disclosure of which is hereby incorporated by reference in its entirety.
In various embodiments, the top sheet is formed from material such as fibrous non-woven fabric or porous plastic film. Preferred non-woven materials include spun-bonded polypropylene, spun-bonded polyethylene, and thermally bonded webs of staple fibers. The back sheet is made from material such as plastic film or a laminate sheet of plastic film. The plastic film is preferably air-impermeable. Such material should be hydrophobic, soft in texture, and strong in tensile strength. An 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. Other materials for forming the back sheet may include polypropylene films, co-extruded films (polyethylene and ethylene vinyl acetate), co-polymer films (polyethylene/polypropylene), and polylaminates (polypropylene nonwoven and polyethylene film). The absorbent core can be made up of any suitable absorbent material, as well as combinations of different types of absorbent materials. For example, the absorbent core may be formed from a mixture of pulp fluff and superabsorbent particles wrapped in a liquid permeable tissue wrap. The superabsorbent particles may be substantially homogeneously mixed with the hydrophilic fibers, or may be non-uniformly mixed. The pulp fluff may be exchanged with synthetic, polymeric, meltblown fibers or with a combination of meltblown fibers and natural fibers. Examples of superabsorbent materials include polyacrylamides, polyvinyl alcohol, polyacrylates, various grafted starches, and the like. A desired super absorbent material is a cross-linked polysodium acrylate, which can be purchased from BASF Corporation of Portsmouth, Va., under the trademark ASAP 2260. The absorbent core may be bonded to the top sheet and back sheet with an adhesive or welding. Leg elastics and waist elastics comprise material such as thread- or tape-like rubber, tape-like plastic foam or plastic film.
The aforementioned embodiments and examples are meant to be for explanatory purposes only, and are not meant to be limiting. Various other configurations are possible within the spirit of the invention. For example, the back sheet may be further elasticized in the back rear portion of the article so as to provide better support during wear. The invention intends to cover all those embodiments within the boundaries defined by the appended claims.
