Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1997-06-17
2001-02-27
Aftergut, Jeff H. (Department: 1733)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S073300, C156S164000, C156S229000, C156S251000, C156S259000
Reexamination Certificate
active
06193828
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of producing a plurality of strips of elastic film starting from a single sheet of elastic film and to an absorbent article for absorbing human exudate, in which said strips are attached in an area to be elasticated.
PRIOR ART
In some prior art absorbent articles e.g. U.S. Pat. No. 3,860,003, a strip of rubber material is applied in a zone of the article which is to be elasticated so that it affords a better fitting for the user and thus provides increased comfort as well as helping to prevent leakage. Such elasticated zones however give rise to many problems such as pressure on the wearer's leg due to the strip which is kept as narrow as possible to save material, yet still wide enough to give a sufficient tension to provide a good fit in all positions of movement. A further problem arises in that the strip itself is made of rubber and thus does not provide a “breathable” material (i.e. a material constructed so as to allow moisture from the body's skin to escape). Since the strip is relatively wide, this can often result in certain areas of the body often being wet which may result in soreness, loss of the skin's resistance to abrasion and even infection.
To solve this problem of moisture release, it is however known in the art to use films of elastic material which are able to “breathe”. Such films are however more expensive and offer only a limited breathing ability in the best of cases. Although relatively thin strips are available (e.g. down to about 6 mm width), handling problems result when trying to use such small strips which makes them impractical for this purpose. Moreover when supplied, each single roll of thin strip must be separately packed which results in wastage as well as greater expense.
As a solution to pressure zones on the wearer's thighs and to improve moisture release, the document U.S. Pat. No. 4,687,477 proposes a solution which replaces the single wide strips in the elasticated leg areas of an absorbent garment by a series of between three and forty-five rubber strands laid side-by-side along the areas to be elasticated. Whilst said rubber strips allow good breathing ability due to the spaces between them, rubber however has the disadvantage of being quite a heavy material. Additionally, rubber is a moulded product and thus a certain thickness has to be maintained in order to obtain a level of uniformity in the rubber strand which provides adequate resistance against breakage. Such thickness in turn increases weight even further. Far more importantly however, since the strips of rubber must be divided later into separate strands and moved laterally apart with respect to each other for application to the product, the mouldings are formed as individual moulded strands of rubber which are held together in a manner which is intrinsically separable. This intrinsic separability is brought about by a weak rubber fusion between adjacent strands, for example by spraying talcum powder onto the individual strands and then allowing a light contact between them. This requirement for separability is however very problematic since the weakness of the inter-strand bond is difficult to control accurately. If the strength is too low (i.e. a very weak bond) this may result in premature splitting of the joint between the strands and, if it is too strong, one of the strands may be torn during attempted separation from the adjacent strand. In either case, the resultant loose strands become difficult to deal with and, when this happens during operation in the machine, the resultant stoppage is very costly, especially in the field of absorbent article manufacture where the production speed is very high (e.g. a belt speed of about 200 m/min).
The present invention thus seeks to provide a means of elastication which gives good breathing ability in the area of elastication, is thin and light and which can be handled without the risk of premature separation of the strands. Thus, when the strips are applied to an absorbent article, the article can be made lighter and cheaper than hitherto.
SUMMARY OF THE INVENTION
The aforementioned problems are solved by the features of the invention.
Preferred features of the invention are defined in the dependent claims.
By adopting the method of the invention, the individual strips produced remain combined as a single sheet of uniform-thickness film having no joints formed on the material before severing into individual strips. This allows easier handling and the avoidance of any measures concerning joint strength control between the individual strips. The film sheet and resultant strips can thus be very thin (e.g. between 5 and 120&mgr;) since there are no separable joints. Moreover, merely by stretching the film after passing through a severing zone, each of the resultant strips becomes narrower and simultaneously forms an intermediate free zone between the strips without any lateral movement. This zone will allow moisture to escape in an elasticated zone of an article, on which the strips are subsequently applied.
The finished absorbent article fitted with such strips will thus have “breathable” elasticated portions which can thus be made very lightweight in comparison to prior art articles.
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Aftergut Jeff H.
Burns Doane Swecker & Mathis L.L.P.
SCA Hygiene Products Aktiebolag
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