Surgery – Means and methods for collecting body fluids or waste material – Absorbent pad for external or internal application and...
Reexamination Certificate
1998-12-07
2002-04-23
Weiss, John G. (Department: 3761)
Surgery
Means and methods for collecting body fluids or waste material
Absorbent pad for external or internal application and...
C604S385010
Reexamination Certificate
active
06376741
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to absorbent articles, in particular sanitary napkins and panty liners comprising compositions providing odour control benefits.
BACKGROUND OF THE INVENTION
Whilst the primary focus of absorbent articles remains the ability of these articles to absorb and retain fluids, another important area of development in this field is the control of oderous compounds contained within the absorbed fluids or their degradation products. There are a wide range of compounds which may be present in an absorbent article during use which result in the formation of malodourous. These compounds include fatty acids, ammonia, amines, sulphur containing compounds and ketones and aldehydes.
The art is replete with descriptions of various odour controlling agents for use in absorbent articles in order to address the problem of malodour formation. These agents can typically be classified according to the type of odour the agent is intended to combat. Odours may be classified as being acidic, basic or neutral. Acidic odour controlling agents have a pH greater than 7 and typically include inorganic carbonates, bicarbonates, phosphates and sulphates. Basic odour controlling agents have a pH of less than 7 and include compounds such as citric acid, boric acid and maleic acid.
Neutral odour controlling agents have a pH of approximately 7. Examples of these types of compounds include activated carbons, clays, zeolites, silicas and starches. For example EPO 348 978 discloses an absorbent article comprising an odour control system wherein the neutral odour controlling particles are selected from carbon, clays, silicas, zeolites and molecular sieves. EPO 510 619 relates to absorbent article comprising odour control complex including a combination of at least 2 agents selected form a group which includes zeolites and silica gels. Similarly, WO 91/12029, WO 91/11977 and WO 91/12030 disclose the combination of zeolites and absorbent gelling materials.
WO 81/01643 relates to the removal of nitrogenous irritants present in waste matter in diapers by the use of an inorganic aluminosilicate zeolite ammonium ion exchange material. In addition silica gel may be present to absorb additional water. Carbon is a preferred component of the system
Carbon has been noted in the art as being particularly effective over a broad spectrum of odours. However, it is not favoured due to its black appearance, which is considered unacceptable by consumers. Hence a currently preferred odour control agent is zeolite. Although zeolites do not have a negative aesthetic profile, the main drawback is its lack of effective odour control over a broad range of odour types.
Hence, there still exists a need to provide an odour controlling agent or system which has an acceptable aesthetic profile such that it is light coloured and provides effective odour control over a wide range of malodourous compounds.
It has now been observed that this need may be addressed by the use of the combination of zeolite with silica to effectively combat a wide range of odours which may be present within an absorbent article. Surprisingly it has been observed that the combination of zeolite with silica results in a synergic effect such that the odour control performance of the combination of zeolite and silica is greater than the mere sum of the components.
An additional advantage of the present invention is that the compounds are all light in colour and thus are not noticeable within the absorbent article and are therefore acceptable from a consumer standpoint. Furthermore, the use of the combination of zeolite and silica results in a reduction on costs of the odour control system
None of the identified prior art has recognised the that this specific combination of zeolite and silica provides the above described benefits.
Another patent application is being filed on the same date as this application. It is entitled “Feminine hygiene absorbent products having a zeolite and silica odour control system” also assigned to “The Procter & Gamble Company”.
SUMMARY OF THE INVENTION
The present invention relates to a activated carbon free absorbent articles comprising a topsheet, a backsheet and an absorbent core characterised in that said sanitary napkin comprises an odour control system comprising the combination of zeolite and silica.
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to absorbent disposable articles such as sanitary napkins, baby diapers, incontinence products and panty liners. The absorbent article of the present invention which is free of activated carbon and comprises the essential features of a liquid pervious topsheet a backsheet and an absorbent core intermediate the topsheet and the backsheet. The absorbent article further comprises as an essential component an odour control system.
Odour Control System
According to the present invention the absorbent article comprises as an essential feature an odour control system comprising zeolite and silica, which is effective over a wide range of malodours.
Zeolite Odour Control Agent
The use and manufacture of zeolite material is well know in the literature and is described in the following reference texts: ZEOLITE SYNTHESIS, ACS Symposium Series 398, Eds. M. L. Occelli and H. E Robson (1989) pages 2-7; ZEOLITE MOLECULAR SIEVES, Structure, Chemistry and Use, by D. W. Breck, John Wiley and Sons (1974) pages 245-250, 313-314 and 348-352; MODERN APPLICATIONS OF MOLECULAR SIEVE ZEOLITES, Ph.D. Dissertation of S. M. Kuznicki, U. of Utah (1980), available from University of Microfilms International, Ann Arbor, Mich., pages 2-8.
Zeolites are crystalline aluminosilicates of group IA and group IIA elements such as Na, K, Mn, Ca and are chemically represented by the empirical formula:
M
2
O.Al
2
O
3
.ySiO
2
.wH
2
O
where y is 2 or greater, n is the cation valence, and w is the water content in the voids of the zeolite.
Structurally, zeolites are complex, crystalline inorganic polymers based on an infinitely extending framework of AlO
4
and SiO
4
tetrahedra linked to each other by sharing of oxygen ions. This framework structure contains channels or interconnected voids that are occupied by the cations and water molecules.
The structural formula of a zeolite is based on the crystal unit cell, the smallest unit of structure, represented by
M
x
[(AlO
2
)
x
(SiO
2
)
y
].wH
2
O
where n is the valence of cation M, w is the number of water molecules per unit cell, x and y are the total number of tedrahedra per unit cell, y/x usually having values of 1-5.
Zeolites may be naturally derived or synthetically manufactured. The synthetic zeolites being preferred for use herein. Suitable zeolites for use herein include zeolite A, zeolite P, zeolite Y, zeolite X, zeolite DAY, zeolite ZSM-5, or mixtures thereof. Most preferred are zeolite A, zeolite Y or mixtures thereof.
According to the present invention the zeolite is preferably hydrophobic. This is typically achieved by increasing the molar ratio of the SiO
2
to AlO
2
content such that the ratio of x to y is at least 1, preferably from 1 to 500, most preferably from 1 to 6.
The absorbent article preferably comprises from 40 gm
−2
to 90 gm
−2
, more preferably from 55 gm
−2
to 85 gm
−2
, most preferably from 60 gm
−2
to 65 gm
−2
of said zeolite.
Silica Odour Control Agent
According to the present invention the odour control system comprises as an essential component silica in combination with the zeolite. Silica i.e. silicon dioxide SiO
2
exists in a variety of crystalline forms and amorphous modifications, any of which are suitable for use herein. In particular, silicas having a high surface area or in agglomerated form are preferred. Silica molecular sieves are not considered to be within the definition of silica as used herein. Preferably the silica is in a highly purified form such that is contains at least 90%, preferably 95%, more preferably 99% silicon dioxide. Most preferably the silica is silica gel having a 100% silica content. Alternatively, t
Gagliardini Alessandro
Guarracino Mario
Bogart Michael
Hickman Ingrid N.
Johnson Kevin C.
Weiss John G.
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