Plastic article or earthenware shaping or treating: apparatus – Preform severing means – Rotating means comprising circumferentially extending...
Reexamination Certificate
1997-06-30
2001-06-19
Watkins, III, William P. (Department: 1772)
Plastic article or earthenware shaping or treating: apparatus
Preform severing means
Rotating means comprising circumferentially extending...
C428S132000, C428S133000, C425S080100, C425S081100, C425S082100, C425S083100, C425S294000, C425S298000, C425S304000, C425S362000, C425S363000, C493S365000, C493S370000, C264S145000, C264S146000, C264S154000, C264S155000, C264S156000, C264S284000, C604S385010
Reexamination Certificate
active
06247914
ABSTRACT:
The present invention relates to a method for perforating a web of material intended for use as a casing sheet in the manufacture of absorbent articles, particularly a casing sheet which is intended to lie proximal to the wearer when using the articles, for instance sanitary napkins, diapers and like articles.
The inner perforated casing sheet of absorbent articles normally includes a liquid-impermeable material, such ;as plastic film, wherein the holes formed by the perforations are present in very large numbers so as to enable liquid, or fluid, to flow satisfactorily into the absorbent body of the article that lies inwardly of the casing sheet.
In the case of outer casing sheets of this kind it is also desirable to obtain a relatively small area of contact of the casing sheet with the wearer's body, so as to produce an inner casing sheet which will be felt to be more airy, drier and less plastic-like by the wearer. This is achieved by forming recesses in the web from which the casing sheet is produced, wherein the holes are preferably orientated in planes which lie generally perpendicular to the plane of the outer sheet. Providing that the casing sheet is comprised of opaque material, this orientation of the holes will also afford the advantage that the body liquid absorbed by the absorption body will be less visible.
SE-B-44 9 298 (corresponding to U.S. Pat. No. 4,626,254) describes and illustrates an inner casing sheet for absorbent articles in which perforated recesses are formed in the casing sheet, wherein the recesses include openings or holes which are orientated in planes that lie generally perpendicular to the plane of the sheet.
These recesses which include holes that lie perpendicular to the plane of the sheet have been formed with the aid of vacuum-forming against a rotating, hollow matrix cylinder, wherein the plastic film is pressed into hollows in the matrix cylinder by the action of hot air and sub-pressure. However, it has been found difficult to obtain controlled and uniform shaping and orientation of the recesses and the holes formed therein simultaneously with the shaping process when practicing the aforesaid method.
Consequently, one object of the present invention is to provide a method for perforating a casing sheet web which will enable the recesses and the holes provided therein to be controlled and forcibly given a more well-defined shape.
This object is achieved with a method according to the invention by first making a large number of discrete cuts in the web as the web is advanced through the nip defined between raised plateaus on a matrix cylinder and knife-edges on a cutting cylinder, and thereafter deforming the web transversely to its plane at parts bordering on each cut, with the aid of a press cylinder which presses the web into hollows in the matrix cylinder such as to create perforated recesses in the web.
The invention also relates to apparatus for carrying out the method, said apparatus being characterized in that it includes a matrix cylinder which has a large number of circumferentially extending rows of mutually separated, raised plateaus, a cutting cylinder which has circumferentially extending knife-edges which are intended to generally touch respective plateaus on the matrix cylinder so as to cut intermittently, the web advanced through the nip defined by the knife-edges and the plateaus, and a press cylinder which is mounted downstream of the cutting cylinder and which has circumferentially extending ribs which are configured to engage in circumferentially extending grooves between rows of plateaus on the matrix cylinder, such as to form in the web recesses which include holes that are orientated in a plane which lies generally perpendicular to the plane of the web.
The present invention also relates to a perforated outer casing sheet, particularly the inner casing sheet of absorbent articles, such as sanitary napkin, diapers or like articles, wherein the casing sheet includes a large number of perforated recesses in which the holes or perforations are orientated in a plane which lies generally perpendicular to the plane of the casing sheet. According to the invention, the recesses are mainly characterized in that they are formed by mutually adjacent, elongated channel-like grooves.. This enables the whole area per unit of surface area to be increased and the contact area with the wearer's body to be reduced, while enabling the elastic properties of the outer casing sheet to be influenced transversely to the grooves as desired.
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Areskoug Stefan
Lindquist Bengt
Strålin Anders
Burns Doane Swecker & Mathis L.L.P.
SCA Hygiene Products AB
Watkins III William P.
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