Absorbent article having an elastic outer cover

Details Absorbent article having an elastic outer cover Absorbent article having an elastic outer cover

2000-08-16

2004-01-20

Lo, Weilun (Department: 3761)

Surgery

Means and methods for collecting body fluids or waste material

Absorbent pad for external or internal application and...

C604S385020, C604S385270

Reexamination Certificate

active

06679869

ABSTRACT:

FIELD OF THE INVENTION
This invention is directed to a laminate having independently movable elastic and film layers. The laminate is particularly suitable for use as an outer cover for absorbent articles.
BACKGROUND OF THE INVENTION
Absorbent articles typically include a film layer to prevent fluids, such as bodily wastes, from leaking through the article. Such films can be breathable, thereby allowing vapors to escape while maintaining the liquids within the article. Absorbent articles typically also include elastic elements in order to create a form-fit in such areas as leg openings and waist openings.
Two or more types of material can be layered together to create a laminate that includes the properties of each material therein. For example, the process of “zero strain” stretch bonding, as disclosed in U.S. Pat. Nos. 5,143,679 and 5,167,897 both issued to Weber, et al., includes bonding at least two layers to one another while in an untensioned (hence zero strain) condition. Of the at least two layers, one of the layers is stretchable and elastomeric and another layer is stretchable but not necessarily elastomeric. The laminate is stretched incrementally through the use of one or more pairs of meshing corrugated rolls which reduce the strain rate experienced by the web. The layer that is stretchable but not necessarily elastomeric, upon being stretched in the laminate, becomes permanently elongated, at least to a degree, so that the laminate will not return to its original undistorted condition upon release of the stretching force. The resulting laminate has z-direction bulking and elastic extensibility in the direction of initial stretching at least up to the point of initial stretching.
Absorbent articles made with a zero strain stretch laminate composite elastic material, such as the absorbent articles disclosed in U.S. Pat. No. 5,151,092 issued to Buell, et al., and U.S. Pat. No. 5,196,000 issued to Clear, et al., have discrete elasticized portions, such as side panels and waist bands. An inherent property in the zero strain stretch laminate is the z-direction bulking which is therefore present in the absorbent articles made with such material. Furthermore, the elastic extensibility of the zero strain stretch laminate is limited to the point of initial stretching. Human beings, particularly babies, are typically active and vary greatly in terms of body contours. Absorbent garments worn by such active people must be able to move with the wearer and remain close to the wearer's skin to avoid leakage from the garment.
Necked spunbond and solid stretch film laminates have been proposed as outer covers that provide superior fit. These designs must stretch, breathe, engage fastener hooks and be aesthetically pleasing all with the same material.
There is a need for a lower priced laminate, suitable for making absorbent articles, that can stretch freely and also provide a high level of breathability.
There is a further need for a laminate, suitable for making absorbent articles, that can provide an aesthetically pleasing appearance at a relatively low cost without fear of leakage.
SUMMARY OF THE INVENTION
The present invention is directed to a laminate that can stretch freely and provide a high level of breathability. This laminate is particularly suitable for making absorbent articles. Furthermore, this laminate is relatively inexpensive to produce and provides an aesthetically pleasing appearance when used to make absorbent articles.
The laminate includes an elastic nonwoven layer, and a barrier film at least partially bonded to the elastic nonwoven layer. The barrier film and the elastic nonwoven layer can suitably be bonded just about the periphery of one or both layers.
The barrier film can have a wide range of breathability, including a WVTR of over 5000 grams/m
2
-24 hours. The elastic nonwoven layer can be any fiberous, or cloth-like, breathable elastic layer. For example, the elastic nonwoven layer can include a neck-bonded laminate, a stretch-bonded laminate, a spunbond-meltblown-spunbond laminate, a spunbonded laminate, or a meltblown laminate.
An absorbent article can be made from the laminate of the invention. For example, the laminate can be used as an outer cover, or backsheet, of a diaper or training pant. The barrier layer and the elastic nonwoven layer can be bonded together just around the leg openings and the waist opening, thereby providing great flexibility so that the elastic layer can move independently of the film layer. In addition, an elastic waistband can be attached to the garment around the waist opening and can be partially elongated when attached, so that the waist opening is maintained closely around the wearer's waist to prevent leakage from the garment. The laminate of the invention can also be used to make swim wear, adult incontinence garments, feminine hygiene products, or medical products.
With the foregoing in mind, it is a feature and advantage of the invention to provide a laminate, suitable for making absorbent articles, that can stretch freely and also provide a high level of breathability.
It is also a feature and advantage of the invention to provide an absorbent article having great flexibility and high breathability.
It is also a feature and advantage of the invention to provide a method of preparing a laminate with independently movable layers.


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