In order to improve comfort and fit, disposable hygienic articles, and particularly those which are intended to be worn around the waist of a user, are commonly provided with elastic components in selected regions of the article. In a pants-type absorbent article, i.e. an article which is pulled on in the same manner as a traditional pair of pants, the selected regions comprise the waist opening and the leg openings. Conventionally, the elastic components used in these regions are in the form of elastic threads or bands which are secured to a substrate, e.g. the outer cover of the article, in a stretched state under a tensioning force. When the tensioning force is released, the elastic components contract and thereby gather the substrate to which they are secured. In this manner, an otherwise substantially inelastic material web can be provided with elastic properties.
The above-described manner of providing elasticised regions on an absorbent article suffers from several drawbacks. For example, securing the elastic components to a running material web in a continuous process is relatively complicated. The elastic components are generally secured to the material web with adhesive, for example hot-melt adhesive or thermosetting adhesive. To ensure that the elastic components do not release from the material web during the production process, it is necessary to ensure that the elastic components bear against the material web until the adhesive has set, dried or hardened. Problems may also arise in synchronizing the tensioning of the different elastic components and in achieving uniform tensioning of the different elastic components independently of the speed of the running web material. Since the extent of elasticity of the thus elasticised material web is directly proportional to the degree to which the elastic components are tensioned, typically 100%, when attached to the material web, during production the articles occupy an area which is substantially greater than that occupied by the finished articles in a relaxed state. This implies that the production facility takes up an undesirably large area. In addition, the production equipment has to be dimensioned to accommodate the tensioning force. A further difficulty is that of handling the finished articles once they have been severed from the running material web, since the articles assume an irregular three-dimensional shape as soon as the tensioning of the elastic components ceases. Folding and packaging of the finished articles have additionally proven to be very difficult steps because of their creased and three-dimensional shape.
Although such elasticised disposable absorbent articles may provide satisfactory comfort and fit, the thus gathered material web can impart a bulky, creased appearance to the article. This implies that it may be difficult to conceal the article under normal clothing. This is particularly problematic for adult users of disposable absorbent pants.
To overcome at least some of these drawbacks, rather than using an elasticised material in disposable absorbent articles, it has been proposed to make at least some regions of disposable absorbent articles of elastic material per se, for example an elastic nonwoven or elastic laminate. By using such material, there is no need to secure a tensioned elastic component to a gatherable substrate. As such, theoretically at least, it is possible to manufacture disposable absorbent articles in a process in which the constituent elastic components are substantially unstretched. Indeed, in WO-A-03/070140 it is proposed to stretch the elastic material web during production to a maximum of 5%.
The present inventors have found that, in order to ensure accurate control of the elastic material web during production, it is necessary to subject the web to a certain minimum tensioning load. On the other hand, to enjoy as many as possible of the advantages that, at least theoretically, are available using an elastic material web vis-à-vis an elasticised web, it is important that the tensioning load be significantly less than the load to attain maximum elastic extensibility of the elastic material web.
USPTO Backgrounds
USPTO Backgrounds