Adhesive bonding and miscellaneous chemical manufacture – Methods – Surface bonding and/or assembly therefor
Reexamination Certificate
1998-11-30
2001-04-17
Crispino, Richard (Department: 1734)
Adhesive bonding and miscellaneous chemical manufacture
Methods
Surface bonding and/or assembly therefor
C156S161000, C156S269000, C428S077000, C604S385240
Reexamination Certificate
active
06217692
ABSTRACT:
TECHNICAL FIELD
The invention relates to a method of producing an elastic laminate wherein an elastic web of material is continuously fed, stretched and attached in stretched condition to a support material in the form of a moving web of material. The invention also relates to an elastic laminate, and an absorbing article such as a diaper, an incontinence protector or a sanitary napkin comprising the elastic laminate.
BACKGROUND
In an absorbing article intended for the absorption of body fluids, it can be desirable for several reasons to attach one or several elastic elements to the article. Such elastic elements are, for example, used in order to form a tight-fitting edge around the leg- and waist openings of a diaper. Furthermore, elastic elements are used to form raised fluid leakage barriers along edge sections of diapers, incontinence protectors and sanitary napkins. It is also possible to use elastic elements to shape an absorbing article so that it conforms better to the body of a user, or so that the article obtains a shape suitable for reception of fluid.
Absorbing articles of the kind intended here are usually produced by continuously joining the different components to form a moving web of material. The simplest way of attaching elastic elements to the absorbing articles is to feed the elastic elements in the form of endless strips or threads and to attach them to the moving web of material. The elastic elements are attached to the web of material in stretched condition, and when the absorbing articles are cut or severed from the web of material, the stretching of the elastic elements ceases, causing them to contract, and at the same time, to contract the material of the absorbing article. Since it is extremely difficult to handle separate, three-dimensionally shaped articles in a manufacturing process, it is desirable to perform the cutting step at as late a stage in the process as possible.
A great disadvantage of attaching continuous elastic strips or threads to the absorbing articles is, however that it is impossible to control the application of the elastic elements to those sections of the articles where it is suitable to have elastic elements.
It is, for example, common during manufacturing of training pants or diapers of the so-called all-in-one type to provide the diaper with elastic elements arranged along the leg-edges in order to create tight-fitting elastic leg cuffs. The term all-in-one diapers refers to diapers which consist of an absorbing insert permanently attached to a liquid impermeable outer cover and which may be joined together around the lower portion of the torso of a user in a pant-like way.
By way of example, elastic threads or strips are used as elastic elements, said threads or strips being attached in a stretched condition along the side-edges or the diaper. When the stretching of the elastic organs ceases the side-edges of the diaper contract. Apart from the fact that elastic leg cuffs are thus formed, those sections of the side-edges which, during use of the diaper, are intended to be in contact with the hips of the user are also wrinkled. Such wrinkling has a number of negative effects. For example the wrinkles of the diaper may cause pressure and be abrasive against the skin of the user. Furthermore, they reduce the fit of the diaper and reduce the possibility of concealing the diaper under the clothes. The presence of wrinkles and folds also makes it difficult to attach fastening means for fastening of the diaper during use.
Sanitary napkins and incontinence protectors for slightly incontinent persons belong to a category of absorbing articles which have a relatively small size. Such articles are intended to essentially fit in the crotch-area of a user and be applied over the genitals of the user, in order to immediately capture secreted body liquid. Absorbing articles of this kind are usually supported by being detachably attached, for example with self-adhesive glue, inside underwear.
It has become increasingly common to provide absorbing articles such as sanitary napkins and incontinence protectors with elastic elements which extend along the side-edges. The elastic elements serve a number of different purposes. By positioning the elastic elements at a distance from the absorption body of the article, it is for example possible to obtain raised fluid barriers along the side-edges. Furthermore, the elastic elements contract the side-edges of the article so that the article is curved in the longitudinal direction, which leads to the formation of a liquid-receiving bowl, at the same time as the curving brings the shape of the article into conformity with the shape of the users body.
As with the earlier discussed all-in-one diapers it may, however, be desirable to arrange elastic elements only along sections of the side-edges of the articles. Sanitary napkins and protectors for slightly incontinent persons are usually worn by healthy and active adults. It is thus extremely important that the articles have a discrete shape which permits them to be worn under ordinary clothing without being visible to others. For this reason, the end-sections of the article are kept free from elastic elements, whereby the end-sections can be in smooth contact with the body of the user so that conspicuous wrinkles and folds are avoided.
In order to solve the problem of attaching elastic elements only along certain sections of an absorbing article, it has been suggested to kill the elastic effect where it is not wanted, for example by heating or by chemical treatment of the elastic elements.
Another way of avoiding elastic effect within certain sections of an absorbing article is to only glue, or in some other way attach, those parts of the elastic element which are intended to be active in the article. Alternatively, when applying adhesive to the entire elastic elements, it is possible to treat those sections where no effect is wanted, with, for example, silicon spray so that they do not adhere to adjacent layers of material or other components. When cutting the elastic elements, these contract and leave a section of the article free from elastic elements in the vicinity of the cut. However, in so doing, an unnecessarily large amount of elastic material is used, and the manufacturing process is made more expensive and more difficult due to the necessity of synchronizing the treatment of the elastic elements with the cutting of the separate absorbing articles. The substances which are used to prevent the elastic organs from adhering can furthermore cause problems if they, by mistake happen to be applied in a wrong position in the process, since attachment of other components in the article may thus be made possible.
A number of various ways of handling and attaching discrete elastic pieces of material have also been suggested. Such solutions, are however complicated and costly and can not be used at the high speeds of manufacturing which are necessary nowadays in order to achieve profitable and rational manufacturing of disposable absorbing articles.
OBJECT OF THE INVENTION
It is thus an object of the invention to provide a method of continuously attaching discrete elastic elements to absorbing articles which are cut from a moving web of material.
A further object of the invention is to transport and attach discrete elastic organs to a moving web of material in a controlled manner.
It is a further object of the invention to achieve an efficient and material-saving method of attaching discrete elastic elements to absorbing articles.
CHARACTERISTICS OF THE INVENTION
The present invention solves the problems associated with handling discrete elastic elements in a manufacturing process by attaching the elastic web of material to a supporting web which has a larger extension across the direction of movement of the web than the web of elastic material, and by attaching the web of elastic material to the supporting web with sections of supporting web protruding laterally from each side of the web of elastic material, whereafter the laminate comprising the sup
Burns Doane Swecker & Mathis L.L.P.
Crispino Richard
Purvis Sue A.
SCA Hygiene Products AB
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