Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
2002-08-22
2004-04-13
Lo, Weilun (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S390000, C604S387000, C604S386000, C604S391000
Reexamination Certificate
active
06719744
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an adhesive closure tape tab for manufacturing absorbent articles such as diapers. In particular, the invention relates to an adhesive closure tape tab that comprises an elastic laminate. The invention further relates to a prelaminated composite tape in stable roll form from which an adhesive closure tape tab can be cut. The invention further provides an absorbent article comprising the adhesive closure tape tab according to the invention.
BACKGROUND OF THE INVENTION
A disposable diaper typically has a thin, flexible, stretchy, low density polyethylene backsheet film, an absorbent core on the inside of the backsheet film, and a porous top sheet overlying the core. Such a diaper is positioned at the crotch of the wearer, the two ends of the diaper extending, respectively toward the front and back. Adjacent edges of the diaper at each side are then either positioned adjacent to each other or overlapped, a strip of pressure-sensitive adhesive tape or mechanical fastener tape being adhered to the back sheet at the border adjacent each of the two edges, holding the diaper closed.
A desirable closure system which is used for disposable articles employs a mechanical fastener, comprising for example, hook and loop fastening components. Mechanical fastening systems have the advantage that they may be repeatedly used for opening and refastening the disposable article. Closure systems which contain mechanical fasteners are described in U.S. Pat. Nos. 5,019,073 and 5,176,671, in European patent applications EP 324 578, EP 563 457 and EP 563 458 and in WO 96/21413.
The exterior of disposable absorbent articles, in particular diapers, nowadays is often a non-woven to give the diaper a cloth like feel. Accordingly, desirable closure systems for use with these diapers preferably also have a non-woven backing so as to have a cloth like feel for the diaper closure system as well. Furthermore, developments have taken place to include elasticity in the closure system which increases the comfort of the wearer of the disposable absorbent article.
WO 99/48455 for example discloses an elastic tab laminate that can be adhered to the edge of an absorbent article. The elastic tab laminate is formed using a co-extruded elastic film comprising at least one elastic layer that has on one face a partially extensible non-woven layer. At the other face, there is provided a pressure sensitive adhesive layer and/or a component of a mechanical fastener system.
EP 704 196 discloses a fastening tape for a disposable diaper. The fastening tape includes a stretchable elastic material secured to one surface of the tape at least at both ends thereof thereby bridging a section of the fastening tape. The length of the fastening tape bridged by the elastic tape is longer that the elastic tape in its relaxed state.
However, the elastic tab laminate and fastening tape disclosed in these two patent applications have the disadvantage that tie skin of the wearer may be exposed to the elastic film which may cause irritation of the skin because the film may rub over the skin during repeated expansion and relaxation of the elastic film. This will in particular be the case with sensitive skins such as the skin of babies. Accordingly, it would be desirable to develop an elastic closure tape tab that would not have this disadvantage and that at the same time provides a good performance, i.e. provides good elasticity and reliable closing of the disposable absorbent article and that is compatible with existing manufacturing methods of disposable absorbent articles. Preferably, the elastic closure tape tab can be manufactured in an easy and cost effective way.
DISCLOSURE OF THE INVENTION
The present invention provides in one aspect, an adhesive closure tape tab that comprises an elastic laminate of an elastic film that has on at least a first major side an expandable fibrous layer of non-woven thermoplastic polymer fibers. The adhesive closure tape tab can be easily manufactured and is compatible with existing manufacturing equipment. Moreover, the adhesive closure tape tabs of the present invention are less irritating for the skin and therefore provide more comfort to the wearer of an adsorbent article having an adhesive closure tape tab according to this invention.
In a preferred embodiment, the expandable fibrous layer of the elastic laminate of the adhesive closure tape tab according to this invention is provided on both major sides of the elastic film. By the term expandable fibrous layer is meant that the fibrous layer can be expanded when the elastic film to which the fibrous layer is secured is stretched. Since the fibrous layer itself is non-elastic, the expandability of the layer is achieved by securing a fibrous layer to the elastic film such that the length of the fibrous layer is longer than the length of the elastic film in its relaxed state. Accordingly, it will be possible to expand the fibrous layer upon stretching of the elastic film until the elastic film is stretched to a length equal to the length of the fibrous layer. Stretching beyond this limit will require substantial increase in the stretch force because it would require deformation of the fibrous layer. The fibrous layer is generally coextensive with the elastic film and will preferably have an expandability of at least 30% and preferably at least 75%, that is to say that the elastic laminate can be stretched by at least 30% and preferably at least 75% of its length in the relaxed state. Typically, the expandability of the fibrous layer is between 50 and 400% and most preferably between 75% and 200%.
The fibrous layer is secured to the elastic film in intervals, i.e. when viewed in the longitudinal direction, portions of the fibrous layer that are connected to the elastic film are alternated with portions of the fibrous layer that are not connected to the elastic film layer. This may be achieved by a technique called ringrolling as disclosed in EP 704196 or alternatively, by corrugating the fibrous layer to form arcuate portions and anchor portions therein and then extruding a molten thermoplastic material thereon that forms the elastic film when cooled. This latter technique is described in detail in WO 99/48455.
The elastic film comprises a material that exhibits elastomeric properties at ambient conditions, i.e. the material will substantially resume its original shape after being stretched. Preferably, the elastomer will sustain only a small permanent set following deformation and relaxation, which set is preferably less than 30% and more preferably less than 20% of the original 50% to 500% stretch. The elastomeric material can be either pure elastomers or blends with an elastomeric phase or content that will still exhibit substantial elastomeric properties at room temperature. Suitable elastomeric thermoplastic polymers include block copolymers or the like. These block copolymers are described in for example U.S. Pat. Nos. 3,265,765; 3,562,356; 3,700,633; 4,116,917 and 4,156,673. Particularly useful are styrene/isoprene, butadiene or ethylene-butylene/styrene block copolymers. Generally, the block copolymers contain an A block and a B block. These blocks may be arranged in any order including linear, radial, branched or star block copolymers. Other useful elastomeric compositions can include elastomeric polyurethanes, ethylene copolymers such as ethylene vinyl acetates, ethylene/propylene copolymer elastomers or ethylene/propylene/diene terpolymer elastomers. Blends of these elastomers with each other or with modifying elastomers are also contemplated.
Viscosity reducing polymers and plasticizers can also be blended with the elastomers such as low molecular weight polyethylene and polypropylene polymers and copolymers, or tackifying resins such as Wingtack™, aliphatic hydrocarbon tackifiers available from Goodyear Chemical Company. Examples of tackifiers include aliphatic or aromatic hydrocarbon liquid tackifiers, polyterpene resin tackifiers, and hydrogenated tackifying resins. Aliphatic hydrocarb
Eynon Stuart L.
Kinnear Christopher M.
3M Innovative Properties Company
Bond William J.
Griswold Gary L.
Lo Weilun
Sprague Robert W.
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