Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
2000-01-10
2003-06-03
Ruhl, Dennis (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S385101, C604S378000
Reexamination Certificate
active
06573424
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to an absorbent article.
BACKGROUND OF THE INVENTION
Absorbent articles have been known for a long time as sanitary articles. They are used, for example, as diapers, incontinence pads or sanitary napkins. Such absorbent articles are capable of absorbing and retaining liquid body exudates, such as urine, menstrual fluid or blood. Sanitary napkins, for example, are used to absorb fluids discharged before, during and after menstruation. Sanitary napkin s are worn on the outside of the body (externally) and thus differ in so far from tampons which are inserted into the female vagina and can thus be referred to as “internal” products.
The use of known absorbent articles is frequently disadvantageous in so far as the bodyside surface, after liquids have been discharged thereon, comprises wet areas which causes discomfort to the wearer. Tests showed that conventional sanitary napkins rewet if only about 5% of the theoretical liquid absorption capacity of the sanitary napkin has been utilized. Moreover, the discharged body fluids often leave visible residues on the surface of the absorbent article. This causes the user of the article to change the absorbent article more often than it would be necessary as far as the absorbency for liquids is concerned.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide an absorbent article, wherein the absorbency of the liquid storage material of the absorbent article is optimally utilized so that as few traces of use as possible are visible on the bodyside surface of the absorbent article, even after prolonged use.
The absorbent article of the invention has the following structure. A liquid-impermeable layer is provided on the side which is away from the wearer's body when said absorbent article is in use. A primary storage layer is provided above said liquid-impermeable layer. A secondary storage layer is provided above said primary storage layer. A compensation layer is provided above said secondary storage layer, and a cover layer is provided above said compensation layer, said cover layer comprising a central opening. The cover layer comprises a mixture of pulp and polymerized alkene, wherein said mixture comprises at least 50% by weight polymerized alkene. Finally, the absorbent article of the invention includes a liquid-permeable top layer which is disposed toward the wearer's body when the absorbent article is in use.
It was found to be particularly suitable for the secondary storage layer to include at least one densified section. Preferably, the at least one densified section extends in longitudinal direction of said article. The at least one densified section should be disposed within the projection of said central opening of said cover layer on said secondary storage layer. Particularly suitable results have been achieved with a secondary storage layer which includes at least five densified sections.
Pulp, for example, is suitable as a material for the secondary storage layer. Local densifications in the secondary storage are obtainable, for example, by embossing grooves into the storage. The storage material positioned below the embossed grooves is thereby densified, while the grooves contribute to a targeted liquid transfer on the storage layer and the absorbent article, respectively.
The cover layer, which includes the central opening, is made of a mixture of pulp and polymerized alkene. The mixture preferably includes at least 50 wt. % of polymerized alkene. Excellent results have been achieved with a polymerized alkene content of from 50 to 80 wt. %, in particular 60 wt. %. The cover layer may also be constructed of two layers such that a first layer of a mixture of pulp and polymerized alkene is applied on a second carrier layer of polymerized alkene. The first layer of pulp and polymerized alkene communicates with said liquid-permeable layer disposed toward the wearer's body when said absorbent article is in use, and said second carrier layer communicates with said compensation layer. Preferred polymerized alkenes are polyethylene, polypropylene and mixtures of polyethylene and polypropylene. Moreover, the cover layer may contain a pigment such as titanium oxide.
It is favorable for the material of the compensation layer to be made from a nonwoven material. The nonwoven material may contain polymerized alkene and/or bicomponent fibers. Furthermore, the surface of the compensation layer which is disposed toward the storage layer may be coated with a surface-active substance which may contain, for example, silicone. The primary storage layer, for example, may consist of an UCTAD material, tissue fluff or a polymer alkene. It is advantageous for the primary storage layer to be constructed such that the peripheral sections thereof are folded inwardly and overlap each other.
Both the liquid-impermeable layer and the liquid-permeable layer may be made using by a polymerized alkene, such as, for example, polyethylene, polypropylene or a mixture thereof. In order to fasten the absorbent article to a garment, the liquid-impermeable layer preferably includes at least one adhesive element and/or adhesive layer. Moreover, the absorbent article of the invention may include laterally disposed flaps. The absorbent article of the invention is preferably used as sanitary product, in particular as sanitary napkin or feminine care liner.
A preferred UCTAD (uncreped through air-dried) material may also be used as primary storage layer. The material includes at least 10 wt. % of high yield pulp fibers, based on its dry weight. A wet strength agent is added in an amount which causes the ratio of wet tenacity to dry tenacity to be at least about 0.1. High yield pulp fibers contain a high amount of lignin which facilitates the wet elasticity of the fibers. The resin bonds formed by the wet strength agent immobilize the wet elastic fibers in a sheetlike structure, which adapts to the structure of the belt on which through drying is effected. During the drying step, the bonds formed by the wet strength agent are cured so that wet-resistant bonds may form which, in turn, impart highly elastic properties to a corresponding web in a wet state. The web maintains this property because, in an UCTAD process, no creping step or other steps are performed which would destroy the bonds again. The UCTAD material is highly suitable to transfer and store liquids because the material is stabilized also in a wet state. Various advantages of the absorbent article of the invention shall now be explained in further detail.
The liquid-permeable top layer which is disposed toward the wearer's body may, for example, be made of a spun-bonded polypropylene. If suitable pigments, such as titanium oxide, are added to this liquid-permeable top cover layer, this layer prevents to a certain extent the liquid stored in the absorbent article from showing through. This bodyside top layer may also be a nonwoven or film material including a centrally disposed opening.
The next layer is the cover layer, which includes a central opening to facilitate penetration of discharged liquids into the layers further below. This opening may, for example, be punched out and exhibit an oval or dog-bone shape. The cover layer, too, may include pigments, which in turn prevents discharged and absorbed liquids from showing through on the surface of the absorbent article. The cover layer further serves to prevent liquid which has penetrated into the absorbent article from flowing back to the surface, so that no re-wetting occurs and the wearer's body is kept dry.
This is achieved with a cover layer which is constituted of a coform material. A suitable coform material is, for example, a polypropylene/pulp mixture with a polypropylene content of more than 50 wt. %. Polypropylene contents of 50 to 80 wt. %, in particular, 60 wt. %, were found to be particularly suitable. A coformr material is prepared using pulp that is defiberized and melt-blown polypropylene is prepared. The defiberized pulp and the polyprop
Aschenbrenner Franz
Raidel Maria
Bogart Michael
Hakle-Kimberly Deutschland GmbH
Pauley Petersen Kinne & Erickson
Ruhl Dennis
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