Bentonite as odor control material

Details Bentonite as odor control material Bentonite as odor control material

1998-06-19

2001-01-16

Ruhl, Dennis (Department: 3761)

Surgery

Means and methods for collecting body fluids or waste material

Absorbent pad for external or internal application and...

C604S368000

Reexamination Certificate

active

06175055

ABSTRACT:

This invention relates to an absorbent article for absorbing bodily fluids comprising an odour control material.
Absorbent articles are designed to be worn by humans to absorb bodily fluids, such as urine, menstrual fluid and perspiration, etc. Examples of absorbent articles include sanitary napkins, pantiliners, disposable diapers, incontinence pads, tampons and the like.
In use, the absorbent articles are known to acquire a variety of compounds, for example volatile fatty acids (e.g. isovaleric acid), ammonia, amines (e.g. triethylamine), sulphur containing compounds (e.g. mercaptans, sulphides), alcohols, ketones and aldehydes (e.g. furaldehyde) which release unpleasant odours. These compounds may be present in the bodily fluid or may be produced by fermentation once the bodily fluid is absorbed into the pad. In addition bodily fluids can contain microorganisms that can also generate malodorous byproducts. Unpleasant odours which emanate from absorbent pads when in use may make the wearer feel self conscious.
An object of the present invention is to provide an absorbent article providing odour control using a material which can be handled easily in production of an absorbent article, and is not expensive.
It has been found that bentonite clays have odour control properties when incorporated in absorbent articles.
The present invention provides an absorbent article having incorporated therein an odour control material for decreasing odours associated with bodily fluids, the odour control material comprising at least 50% by weight, preferably at least 80% by weight, of a bentonite clay.
According to one embodiment the absorbent article includes a bentonite clay as the only odour control material.
A number of odour control materials have previously been suggested for use in absorbent articles which, although efficient at odour control, are very expensive. Examples are carbon black and zeolites. The advantage of bentonite clays is that, on the one hand, they are effective as odour control materials and, on the other hand, they are readily available and relatively cheap. Accordingly, relatively large amounts of bentonite clay can be included in an absorbent article without substantially increasing the cost. Thus, whilst it may be necessary to use more bentonite as an odour control material in an absorbent article than, for example, carbon black or zeolite, the equivalent degree of odour control can be achieved more cheaply by use of bentonite.
The fact that more bentonite is used than, for example, carbon black or zeolite for an equivalent odour control effect is itself an advantage. Thus the requirements for production equipment and process control are less stringent, for bentonite than is the case for carbon black or zeolite where small amounts of materials have to be metered accurately into each product. In addition, as well as being an odour control material, bentonite is also an absorbent and, when incorporated into an absorbent article in the quantities appropriate for odour control, it can also supplement the absorbent capacity of the product. Finally, in contrast to carbon black or zeolite, bentonite is a naturally occurring mineral and may thus have better acceptability to consumers in the context of absorbent products such as sanitary products.
Any suitable bentonite clay with odour control properties can be used according to the invention. Examples include:
calcium bentonite, for example in granular form
sodium bentonite.
Preferably, the bentonite clays of the present invention comprise at least about 90% montmorillonite. More preferably, the clays comprise at least about 95% montmorillonite.
It is particularly preferred to use such calcium or sodium bentonite in the unactivated state. As is known in the art, clays may be activated by either heat treatment or acid treatment. As used herein, a bentonite clay is “unactivated” if it can be provided using such relatively simple processing steps, as mining, drying to remove at least some of the loosely held (not structural) water, grinding, and sizing (e.g. agglomeration and/or screening) without an acid treatment or heat treatment (beyond what may be necessary to dry the clay). As noted above, a particular benefit of the unactivated bentonite clays of the present invention is their low cost. One contributor to this low cost is the clays of the present invention do not require an activation process step to be effective as odor absorbers. An exemplary unactivated calcium bentonite is the granular calcium bentonite available from Laviosa Chimica Mineraria SpA as DETERCAL G IF. Such unactivated calcium bentonites are mined, dried, ground, and agglomerated prior to shipment. An exemplary unactivated sodium bentonite is available from ABI, Inc. of Palatine, IL as AP BASE CLAY. Such unactivated sodium bentonites are mined, dried and sized prior to shipment.
The absorbent article according to the invention may be a sanitary napkin, a pantiliner a disposable diaper, an incontinence pad, tampon or the like. According to one aspect of the invention the absorbent article is a pantiliner. According to another aspect of the invention the absorbent article is a sanitary napkin.
The amount of bentonite clay which may be used in the absorbent article as an odour control material can be readily determined by the skilled person bearing in mind the size of the absorbent article in question. For example, a suitable quantity of bentonite clay which may be used in a pantiliner, is from about 0.25 to 2.0 g, preferably the quantity is from about 0.5 to 1.5 g.
The absorbent article may be of conventional construction and may include other conventional components such as antimicrobial agents and ionic absorbents, for example absorbent gelling material (AGM). The quantity of AGM which may be added may also readily be determined by the skilled person for each absorbent article. For example about 0.05 to 0.7 g, preferably about 0.1 to 0.5 g, AGM may be appropriate for adding to a pantiliner.
The bentonite clay as an odour control material may be incorporated into the absorbent article by methods known in the art, for example the clay may be layered on the core of the absorbent material or mixed within the fibres of the absorbent core. The odour control material is preferably incorporated between two layers of cellulose tissue and, optionally, the material may be bonded between two cellulose tissue layers with, for example, a hot melt adhesive or any suitable bonding system. For example the odour control material may be incorporated in a layered structure in accordance with WO 94/01069 or Italian Patent Application TO 93A 001028.


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