Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
1998-12-11
2003-09-23
Reichle, Karin (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S365000, C604S367000, C604S378000, C604S387000
Reexamination Certificate
active
06623464
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to absorbent articles, in particular sanitary napkins with improved comfort, particularly using breathable backsheets while maintaining protection level performance.
BACKGROUND OF THE INVENTION
The development of absorbent articles, particularly catamenial products, are driven by two need of the consumer, protection and comfort.
One means for providing consumer comfort benefits in absorbent articles is by the provision of breathable products. Breathability has typically concentrated on the incorporation of so called ‘breathable’ in the absorbent articles. Commonly utilized breathable backsheets are microporous films and apertured formed films having directional fluid transfer as disclosed in for example U.S. Pat. No. 4,591,523. Both these types of breathable backsheets are vapour permeable allowing gaseous exchange with the environment. This thereby allows for evaporation of a portion of the fluid stored in the core and increases the circulation of air within the absorbent article. The latter is particularly beneficial as it reduces the sticky feeling experienced by many wearers during use, commonly associated with the presence of an apertured formed film or film like topsheet, particularly over extended periods of time. This is a result of topsheets designed to achieve a clean and dry appearance. These topsheets tend to be smooth thereby minimizing the build up of fluid on the surface of the topsheet. However, the benefits of a smooth textured surface are achieved at the expense of consumer comfort, particularly under hot and humid conditions.
However, the main drawback associated with the use of breathable backsheets in absorbent articles is the negative effect on the protection level performance, by leakage known as wet through onto the uses' garment. Although, breathable backsheets in principle only allow the transfer of materials in the gaseous state, physical mechanisms such as extrusion, diffusion and capillary action may still occur and result in the transfer of the fluids from the absorbent core through the backsheet and onto the users' garments. In particular, these mechanisms become more dominant if the product is utilised during physical exertion, or for heavy discharge loads or over extended periods of time. Thus, whilst the incorporation of breathable backsheets in absorbent articles is highly desirable from a comfort standpoint, since the primary role of a backsheet still remains the prevention of liquid leakage, such breathable backsheets cannot be satisfactorily incorporated into products.
The problem of wet through onto users' garments due to the incorporation of such breathable backsheets in absorbent articles has indeed also been recognised in the art. Attempts to solve the problem have mainly resided in the use of multiple layer backsheets such as those illustrated in U.S. Pat. No. 4,341,216. Similarly European patent application no. 710 471 discloses a breathable backsheet comprising an outer layer of a gas permeable, hydrophobic, polymeric fibrous fabric and an inner layer comprising an apertured formed film having directional fluid transport. The backsheet construction preferably has no liquid transport/wet through under certain specified test conditions. Also European patent application no. 710 472 discloses a breathable backsheet consisting of at least two breathable layers which are unattached to one another over the core area. The backsheet construction preferably has no liquid transport/wet through under certain specified test conditions.
U.S. Pat. No. 4,713,068 discloses a breathable clothlike barrier for use as an outer cover for absorbent articles. The barrier comprises at least 2 layers, a first layer having a specified basis weight, fibre diameter and pore size and a second layer comprising a continuous film of poly (vinyl alcohol) having a specified thickness. The barrier also has a specified water vapour transmission rate and level of impermeability.
However, none of the above proposed solutions have been able to provide a fully satisfactory solution to the problem of breathable backsheet wet through under all conditions. Furthermore, another problem associated with the exemplified multi layer backsheets is an increase in total thickness of the product and a reduction in the flexibility, both of which result in a consumer noticeable reduction in product comfort.
An alternative proposed solution to the problem of breathable backsheet wet through relates to the improvement of the absorbent material such that little or no liquid comes into contact with the backsheet, thereby preventing wet through. This is typically achieved by increasing the amount of absorbent material in the article. However, this results in an absorbent article which is extremely thick which is highly undesirable from a consumer comfort standpoint. Hence, the absorbent article whilst having the required protection level and still maintaining some comfort benefits by the presence of the breathable backsheet, suffers from a lack of comfort from a different source, in this case the increased dimensions of the article.
In addition the above solution also results in a reduction in the flexibility of the article, particularly evident as an increase in the cross section stiffness. It is however also well established that in order to be comfortable for the wearer absorbent articles need to be cross sectionally flexible. It is believed that the more cross sectionally flexible an absorbent article is, the less will it be noticeable to the wearer. Thus flexibility is another highly desirable comfort requirement of modern absorbent articles.
EPO 705 583 and EPO 705 584 propose longitudinally flexible absorbent articles which are vapour permeable. However, the exemplified absorbent articles are typically very thin and do not address the absorbency capacity of the article or the problem of wet through.
Thus it not currently possible to provide a comfort improvement to absorbent articles such as by the incorporation of breathable backsheet, without negatively impacting protection levels. In the alternative, if the result of protection level problem is then addressed either by using a multi layered backsheet or increasing the thickness of the core, there is a further negative impact on the comfort level of the article and vice versa.
Consequently, as the incorporation of breathable backsheets in absorbent articles results in reduction of the protection level, further desirable product comfort modifications such as reducing the thickness of the product and improving the flexibility of the product which would further acerbate the problem may not be incorporated in the absorbent article.
Thus, there exists a dichotomy in the means available to provide increased consumer comfort in absorbent products and acceptable protection levels. It is therefore an objective of the present invention to provide an absorbent article having improved comfort which maintains an acceptable level of protection.
It has now been found that this objective may be achieved by the provision of an article whose individual elements must meet certain key functional parameter criteria in terms of comfort provision and/or protection such as the backsheet wet through/liquid permeability, the topsheet dryness, the core caliper and core vapour or vapour/air permeability. Furthermore, these elements are combined such that the resultant product, in addition to these individual elements, meets overall criteria such that it has a certain dryness index and sensory index. The present invention has identified the key components which affect the principle comfort requirements of flexibility, breathability, dryness and caliper and the key components of protection such as liquid retention/wet through and rewet. Surprisingly, it has been found that the specfic combination of these components, provides an article delivering both high protection levels as well as high comfort to the consumer. In particular it is believed that breathability must be considered in terms of t
Bewick-Sonntag Christopher Philip
Carlucci Giovanni
Cintio Achille Di
Ammons Bridget D.
Fitzpatrick Matthew P.
Johnson Kevin C.
Reichle Karin
The Procter & Gamble & Company
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