Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Patent
1995-03-16
1997-03-04
Jordan, Charles T.
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
604358, A61F 1315
Patent
active
H00016390
DESCRIPTION:
BRIEF SUMMARY
This invention relates to disposable catamenial devices. More particularly it relates to disposable sanitary napkins and pantiliners designed to be located externally of the vaginal cavity and to be held in position adjacent the vaginal opening by the wearer's undergarment.
A major design objective of catamenial devices of this type is that they be non bulky whilst providing adequate menses absorption capability in order to be comfortable and non-obtrusive as well as effective in use.
The use of water insoluble particulate hydrogel material as an absorbent material in disposable absorbent articles such as disposable diapers, incontinence briefs and catamenial devices has permitted significant reductions to be made in the bulk of such articles without a sacrifice in absorbent capacity. Within the field of catamenial devices, a category of thin flexible sanitary napkin products has been developed and introduced commercially that takes advantage of the high absorbency of particulate hydrogel material. The commonly assigned EP-A-0336578 discloses a sanitary, napkin of this general type.
Nevertheless, in spite of the commercial introduction of catamenial devices incorporating particulate hydrogel material as the, or the major component of the, absorbent medium, there remains a perception amongst users that thin sanitary napkins are only suitable for light or low menstrual flows or as pantiliners. Attempts to change this perception by increasing the level of hydrogel material in the structure have proved ineffective as such increases in level have resulted in a pronounced `gel blocking`effect with a loss in efficiency of usage of the hydrogel material and, under certain conditions, adverse effects on overall absorbent capacity.
When a hydrogel material absorbs aqueous liquids and swells, the ability of the resultant gel to maintain its integrity, particularly under pressure correlates with the `gel strength` of the material. `Gel strength` is a composite of several properties, but for the purposes of the present invention can be expressed in terms of the modified Absorbent Gel Expansion Pressure test (hereinafter referred to as the modified AGEP test). References hereinafter to gel strength values are to the values obtained in this test.
The particulate hydrogel materials used in current commercially available disposable absorbent products have been developed primarily for disposable diapers in which the major load is urine. Whilst such hydrogel materials provide a satisfactory balance between absorbency and other properties such as gel strength when exposed to liquids that are almost entirely aqueous, they appear not to be optimum for more complex liquid materials such as menses. Accordingly a need has been identified for a particulate hydrogel material that is menses specific i.e. has the capability of absorbing blood and protein-containing liquids without gel blocking.
The Applicant has now surprisingly found that certain types of hydrogel material which have high gel strength but relatively low absorbent capacity and which also retain, or more preferably increase, their gel strength after absorbing a liquid load, provide enhanced performance in catamenial devices. This gel strength behaviour, when the hydrogel is subjected to a liquid load, minimises the gel blocking effect and permits the majority, if not all of the absorbent capacity to be utilised.
According to the present invention there is provided a catamenial device comprising a liquid permeable layer having a first body-facing surface and a second opposed surface, an absorbent body disposed adjacent the opposed surface said absorbent body comprising a water insoluble particulate hydrogel material at a weight concentration of at least 5 g/m.sup.2 of the plan area of the absorbent body, a liquid impermeable barrier layer disposed on the surface of said absorbent body remote from said liquid permeable layer, and adhesive attachment means for securing said device to a garment, said attachment means being disposed on the surface of said device opposed to
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Chelliah Meena
Jordan Charles T.
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