Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
2001-03-30
2003-07-15
Lo, Weilun (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S385030, C604S386000
Reexamination Certificate
active
06592561
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to sanitary absorbent articles such as feminine sanitary napkins and incontinence pads, and, more particularly, to sanitary absorbent articles having a flange seal that is resistant to tearing.
BACKGROUND OF THE INVENTION
Sanitary absorbent articles are, generally, large-scale commercially manufactured articles used to absorb and retain bodily exudates. Such articles are convenient in that they are often economical yet disposable; they 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 two decades. One of such advances was the addition of a flap projecting laterally from each longitudinal side 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, may simply be comprised of additional material added to the article after its formation.
When such articles are in use, the flaps are folded over the edges of the wearer's undergarment. They thus may 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's undergarment. The flap concept has generally met with success in the marketplace, and articles with flaps of various configurations and conformations are available to the consumer.
Conventional wisdom on the part of both designers and consumers has to date dictated that 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 portion of the main body of the article and projecting (and tapering) away therefrom to the top of the trapezoid. The size of the flap may vary from article to article.
The difficulty with absorbent articles of the trapezoidal and other conventional flap configurations is that the absorbent articles are designed and manufactured in a flat state, while in use the article should generally adopt a two- and often three-dimensional curvature in order to correctly interface with the body of the wearer. By two-dimensional curvature it is meant that the article will curve along one axis of the three-dimensional coordinate system formed by the longitudinal centerline of the article, the transverse centerline of the article, and the line perpendicular to both. By three-dimensional curvature it is meant that the article will curve along more than one axis of a three-dimensional co-ordinate system (such a system having three orthogonal axes).
As an example, where the absorbent article is a feminine sanitary napkin, and is in use, a cross-section of the article in both the sagittal plane of the wearer's body (i.e. the longitudinal axis of the article) and the frontal or coronal plane of the wearer's body (i.e. the transverse axis of the article) would most likely be curved. The flaps, however, are generally designed to be folded about a linear folding axis commonly located along the line of juncture of the flap with the longitudinal side of the main body of the article. The difficulty with such a linear folding axis is that the edges of the wearer's undergarment, about which the flaps are folded, are curved. Moreover, the undergarment edges usually contain an elastic material for snugly securing the undergarment about the legs of the wearer. Depending on the force exerted by the elastic material, a curved shape may be imparted to the flaps and the central portion of the main body of the article causing them to lift off the undergarment and wrinkle, or a flattened shape may be imparted to the edges of the undergarment causing them to not fit snugly against the legs of the wearer. In both cases, the comfort and efficiency of the article and its flaps are compromised. Moreover, the larger the flap, the more acute the problem. Thus while large flaps alleviate some difficulties on one hand (i.e. side leakage protection), they create problems on the other (i.e. instability and stress).
In order to alleviate the difficulties of conventional flap designs, a sanitary napkin has been proposed 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. 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.
It has been observed, however, that such strong attachment ability of the flaps may cause the flaps to tear apart from the main body when the sanitary napkin is removed from the undergarment. Usually, the wearer will not detach the flaps from the undergarment before lifting away the 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, often causing 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.
When the sanitary napkin tears, the tear usually originates in the peripheral area of the sanitary napkin that is called the “flange seal”. The flange seal is an area of juncture between two component layers of the sanitary napkin. Typically, the cover layer and the liquid-impervious barrier layer of the sanitary napkin (their respective functions will be described later in this specification) are joined together to enclose, at least partially, the absorbent system of the sanitary napkin. The junction between the components that form the flange seal may be such that the components are directly united to one another or united to one another through one or more intermediate components.
Conventional manufacturing techniques employ a heat and pressure seal method that uses the application of pressure and/or heat to bond the layers of the sanitary napkin that form the flange seal. With this technique, the pressure applied on the layers forming the flange seal reduces the ability of the flange seal to resist shear stress. Without intent of being bound by a specific theory, this may be explained by the distortion that the materials of the layers forming the flange seal undergo during the heat and pressure seal operation. The high levels of pressure and heat have the effect of reducing the caliper of the layers to the point where the material is literally crushed which effectively reduces its ability to withstand shear stress.
When shear stress is applied to a flange seal formed by using a heat and pressure seal technique, having an order of magnitude observed when a sanitary napkin is removed by the wearer from the undergarment with the flaps still attached to the undergarment, it can produce a tear across the flange seal. The tear can then propagate to other components of the sanitary napkin, such as the flaps, and ultimately cause one or both flaps to separate from the main body of the sanitary napkin.
Considering this background, it clearly appears that there is a need in the industry to develop an improved flange seal for a sanitary absorbent article that can better resist shear stress by comparison to prior art flange seal configurations.
SUMMARY OF THE INVENTION
According to one broad aspect the invention provides a sanitary absorbent article comprising:
a main
Brisebois Henri
Simard Jean-Sebastien
Johnson & Johnson Inc.
Lo Weilun
Stephens Jacqueline F
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