MXPA01005244A - Process and apparatus for making selectively apertured web materials - Google Patents

Abstract

The present invention provides a method for selectively aperturing a web material. The web material is weakened along a plurality of regions and then at least a portion of the web material comprised in the weakened regions is removed. Thus, a plurality of apertures in the web material is obtained.

Description

PROCESS AND APPARATUS FOR DEVELOPING SELF-DRILLED WIRING MATERIALS FIELD OF THE INVENTION The present invention relates to weft materials with openings and method for making them, and an apparatus for making them. The weft materials with apertures are particularly well suited for use in disposable absorbent articles such as diapers, incontinence briefs, training pants, feminine hygiene garments, and the like.

BACKGROUND Weft materials such as for example nonwoven webs, films, and the like can be manufactured in products and product components cheaply so that the products can be seen as disposable after only one or some uses. Representative of these products include disposable absorbent articles, such as diapers, incontinence briefs, training pants, feminine hygiene garments, and the like. Babies and other incontinent individuals carry disposable absorbent articles such as diapers to receive and contain urine and other exudates from the body. The absorbent articles function both to contain the discharged materials and to isolate these materials from the wearer's body and from the wearer's clothing and bedding. Disposable absorbent articles having many different basic designs are known in the art.

A typical absorbent article includes a liquid permeable topsheet, a liquid impermeable backsheet attached to the topsheet, and an absorbent core positioned between the topsheet and the backsheet. Weft materials are often used as the top sheet because they are permeable to liquid and provide a benevolent surface for the skin. However, in certain uses the weft materials do not work at all well as a top sheet since the exudates of the body sometimes raise or get to trap in the weft material and in this way, get to be trapped against the user's skin . A solution to the above mentioned problem is to provide openings in the weft material in such a way that exudates from the body can easily penetrate through the weft material and into the underlying absorbent core. Unfortunately, certain techniques used to form the weft materials with openings are either expensive, creating an undesirable rough feeling against the wearer's skin, or are subject to tearing, particularly when the weft material is to be used with openings as a sheet superior in a disposable absorbent article. To overcome the problems of the prior art web material, a process for making selectively perforated nonwoven webs has been taught in PCT Publication No. WO 97/11662. In this process, a nonwoven web is weakened in a plurality of regions and then a tension force is applied to the non-woven web causing the non-woven material to break into the plurality of weakened regions creating a plurality of openings in the web. woven coinciding with weakened regions. Therefore, during this process, material from the raster material is not removed. The present invention provides an alternative process for making a weft material with openings by removing the weft material from weakened regions. The present invention further provides an apparatus for making the weft material with openings, and a disposable absorbent article comprising the same.

BRIEF DESCRIPTION OF THE INVENTION The present invention provides a process for selectively piercing a weft material. The process comprises the steps of providing a web material, of selectively weakening a plurality of regions of the web material, and of removing at least a portion of the web material comprised in the weakened regions using a technique selected from the group of blown with gas and lug. It is another aspect of the present invention to provide an apparatus for selectively piercing a weft material. The apparatus comprises a means of supplying the raster material, a weaving means of the weft to selectively weaken a plurality of regions of said weft material, and a weft removal means to remove at least a portion of the weft material comprised in the weakened regions. It is another object of the present invention to provide an absorbent article comprising the weft material with selective apertures made in accordance with the process of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS Although the description concludes with the claims pointing out in a particular way and claiming differently the exposed matter that is considered as formant of the present invention, it is believed that the invention will be better understood from the following description which is taken in combination with the accompanying drawings and in which like designations are used to designate substantially identical elements, and in which: Figure 1 is a schematic representation of an illustrative process for selectively perforating a non-woven web of the present invention; Figure 2 is an enlarged perspective illustration of a weakened weft means of the apparatus of the present invention; Figure 3 is an enlarged perspective illustration of the weft removal system of an apparatus of the present invention; Figure 4 is a plan view of a disposable diaper embodiment of the present invention having portions cut away to reveal the underlying structure, the inner surface of the diaper being given to the observer.

DETAILED DESCRIPTION OF THE INVENTION Referring to Figure 1 therein schematically illustrated at 100 a process for selectively perforating a suitable weft material, for example, to be used as a topsheet in a disposable absorbent article. As used herein, the term "weft material" refers to a sheet material made from a thermoplastic material, or a composite or laminate comprising two or more such sheet materials. For example, a weft material may be a fibrous web, a non-fibrous web, or the like. A weft material suitable for the present invention is essentially two-dimensional, that is, the thickness of the weft material is much smaller than its longitudinal dimension and its transverse dimension. Additionally, the transverse dimension of the weft material is substantially less than its longitudinal dimension. The longitudinal dimension preferably exceeds the transverse dimension by a factor of 100, most preferably the longitudinal dimension of the weft material of the present invention is essentially infinite. As used herein, the term "fibrous web" refers to a web having a structure of individual thermoplastic fibers or threads which are interposed such as a nonwoven web, a woven web, an interwoven web, or the like. The fibrous webs of the present invention can be absorbent or non-absorbent, liquid permeable, or liquid impervious. As used herein, the term "non-fibrous webs" refers to a web having a uniform structure such as a film and made of a thermoplastic material. In accordance with the process of the present invention, a weft material is provided without openings to the process. In one embodiment of the present invention, the apertureless weft material 102 is unwound from a supply roll 104 and travels in a direction indicated by the arrows associated therewith as the supply roll 104 rotates in the direction indicated by the arrows associated with it. Alternatively, the weft material 102 may be formed in line, for example, by known extrusion processes of nonwoven material, such as, for example, known meltblown processes or known spunbond processes, and passed directly from the grip space 106 without being first attached and / or stored in a supply roll. In one embodiment of the present invention, the weft material is a nonwoven web. As used herein, the term "nonwoven web" refers to a web having a structure of individual thermoplastic fibers or threads which are interleaved, but not in any regular, repeatable manner. The nonwoven web 102 may be extensible, elastic, or not elastic. The non-woven web 102 can be a spin-linked web, a meltblown web, or a carded bonded web. If the nonwoven web is a web of meltblown fibers, it may include microfibers or blown in the molten state. The nonwoven web 102 can be made of polymers that form fiber, such as, for example, polyolefins. Exemplary polyolefins include one or more of polypropylene, polyethylene, ethylene copolymers, propylene copolymers, butene copolymers, polyamides, two-component fibers, polyethylene terephthalate, combinations thereof, and the like. In another embodiment, the non-woven material may be a multilayer weft having, for example, a first carded web having a basis weight of between 5 grams per square meter and 100 grams per square meter, preferably between 5 grams per meter square and 60 grams per square meter, and a second carded weft that has a basis weight of between 5 grams per square meter and 100 grams per square meter, preferably between 5 grams per square meter and 60 grams per square meter. In another embodiment, the nonwoven web 102 may be a multi-layer material having, for example, at least one layer of a spin-linked web attached to at least one layer of a meltblown web, one web linked carded, or other suitable material. For example, the non-woven web 102 can be a multilayer web having a first layer of spin-linked polypropylene having a basis weight of about 5 to about 100 grams per square meter, a meltblown polypropylene layer that have a basis weight of about 5 to about 100 grams per square meter, and a second layer of spin-linked polypropylene having a basis weight of about 5 to about 200 grams per square meter. Alternatively, the non-woven web may be a layer of simple material, such as, for example, a spin-linked web having a basis weight of about 5 to about 300 grams per square meter or a meltblown web that have a basis weight of about 5 to about 200 grams per square meter. The nonwoven web may be attached to a polymeric film to form a laminate. The nonwoven web 102 may also be a composite material formed from a mixture of two or more different fibers or from a mixture of particulate fibers. Such mixtures can be formed by adding fibers and / or particles to the gaseous stream in which the melt blown fibers or the spunbonded fibers are carried in such a way that an intimate entanglement of the fibers and other materials occurs by example, wood pulp, staple fibers and particles, before the collection of the fibers. The non-woven web of fibers must be bonded together to form a coherent weft structure. Suitable bonding techniques include, but are not limited to, air bonding, chemical bonding, thermal bonding, such as spot calendering, hydroentanglement, and sewing. As used herein, the term "microfibers" refers to fibers with small diameter that have an average diameter of no more than about 100 microns. As used herein, the term "meltblown fibers" refers to the fibers formed by extruding a molten thermoplastic material through a plurality of fine die capillaries, usually circular, such as melted filaments or filaments in a gas stream (eg, example, gas) of high speed that attenuates the filaments of the molten thermoplastic material to reduce its diameter, which can be a microfiber diameter. Subsequently, the meltblown fibers are carded by the high velocity stream and deposited on a collector surface to form a web of randomly dispersed meltblown fibers. As used herein, the term "spunbonded fibers" refers to small diameter fibers that are formed by extruding a molten thermoplastic material as filaments from a plurality of thin, usually circular, capillaries of a yarn with the diameter of the extruded filaments that are then rapidly reduced as in, for example, stretched by extrusion or other well known spin bonding mechanisms. As used herein, the term "polymer" generally includes, but is limited to, homopolymers, copolymers, such as, for example, block, graft, random and alternating copolymers, terpolymers, etc., and mixtures and modifications thereof. In addition, unless specifically limited otherwise, the term "polymer" must include all possible geometric configurations of the material. These configurations include, but are not limited to, isotatic, syndiotactic and random symmetries. In another embodiment of the present invention, the weft material is a polymeric film material. Suitable polymeric film materials include but are not limited to polyelefins, such as polyethylene, polypropylene, ethylene copolymers, propylene copolymers, and copolymers of butene, nylon (polyamide); polymers based on metallocene catalyst; poly (methyl methacrylate); polystyrene; polyvinylchloride); polyester; polyurethane; compatible polymers; compatible copolymers; and mixtures, laminates and / or combinations thereof. After being supplied to the process, a plurality of regions 202 of the weft material 102 is selectively weakened 200 as shown in Figure 2. In one embodiment of the process of the present invention, the step of selectively weakening a plurality of regions 202 of the Weft material 102 comprises a step of selectively heating the plurality of regions 202. The regions 202 can be heated by applying electromagnetic waves including but not limited to infrared and laser, pressure, ultrasonic waves, or a combination thereof. In one embodiment of the present invention, the regions 202 are only preheated to a temperature below the melting point of the weft material. In this case, the generation of the potentially sharp edges of the molten material is reduced. Alternatively, the step of selectively weakening the regions 202 of the weft material 102 may comprise a step of selectively applying a chemical agent to the regions 202. For example, the strength of the weft material in the regions 202 may be reduced by way of that agent. In one embodiment of the process of the present invention, the weakened regions of the weft material may circumscribe substantially less weakened regions or even regions without weakening. For example, weakened regions can take the form of a hollow circle, ellipse, square, or the like. In one embodiment of the process of the present invention, the exterior of the weft material of the weakened regions can be stabilized by melting by applying a pressure simultaneously with the weakening step. Subsequent to the step of weakening 200 a plurality of regions of the weft material at least a portion of the weft material comprised in the weakened regions of the weft 202 is removed 300 using a technique selected from the gas blowing, tearing group. After removing the web material, a plurality of apertures 204 remain in the weft material 202 at the sites of the weakened regions 202. The size of the apertures 204 may differ somewhat from the size of the weakened regions depending on the settings of the process and properties of the raster material. In case the weakened regions circumscribe substantially less weakened regions, at least a portion of the weft material comprised in the less weakened regions can be removed together with the weakened weft material. In one of the embodiments of the apparatus of the present invention, a uniform pressure is applied to the main upper surface 180 of the weft material by blowing gas through the web from the main top surface 180 towards the main bottom surface 182. Since the Weft material comprises a plurality of weakened regions 202 upon reaching the weft remover means, these regions 202 are more likely to fail under the applied pressure than the untreated regions. The flow of gas through the weft material 202 (and thus the pressure exerted on the surface 180 of the weft material) has to be chosen such that at least a portion of the weft material comprised in the weakened regions 202 is Removed from the raster material and carried away with the gas. Simultaneously, the gas flow must also be chosen such that at least a part of the integrity of the web is maintained after the removal of the web material from the weakened regions 202. In one embodiment of the process of the present invention , the gas flow can be directed selectively through the weakened regions 202 of the weft material 102. In an alternative embodiment of the present invention, at least a part of the weft material comprised in the weakened regions 202 can be removed by tearing, i.e., by exerting a physical force on the weft material to be removed. In this case, the tensile force has to be chosen in such a way that at least a portion of the weft material comprised in the weakened regions 202 is removed from the weft and in such a way that at least a part of the integrity of the weft plot is maintained after the removal of the weft material from the weakened regions 202. Unidirectionality of the process of removing the weft material from the weakened regions may impose a unidirectionality of the resulting edges of the opening. For example, some of the weft material such as fibers that have been in close proximity to the weakened weft material prior to the removal of the latter may be oriented towards the main under surface by the removal process. This weft material can even project from the main lower surface, thus defining the edge of a three-dimensional opening. After the weave material of the weakened regions is removed, the weft material 102 can be wound onto a winding roller 170 and stored. Alternatively, the weft material 102 can be fed directly to a production line where it is used to form a topsheet in a disposable absorbent article. It is another aspect of the present invention to provide an apparatus for making a selectively perforated weft material according to the present invention. The apparatus of the present invention comprises a weft material supply means, a weft weakening means 108 for selectively weakening a plurality of regions of the weft material, and a weft removing means 132 to remove at least a portion of the weft material. Weft material comprised in said weakened regions. In one embodiment of the apparatus of the present invention, the medium supplying the weft material comprises a supply roll 104 from which the weft material 102 is unwound. Alternatively, the means supplying the weft material may comprise a medium of production of the weft material such as a non-woven extrusion system that produces the weft material in line. In one embodiment of the apparatus of the present invention, the weft weakening means is formed by the rollers 110 and 112. In this case the weft material 102 is passed through the grip space 106. Referring now to the embodiment of the present invention shown in Figures 1 and 2, the weakening means of the weft 108 may comprise a patterned roller 1 10 and a smooth anvil roller 1 12. One or both of the patterned roller 1 10 and roller of smooth anvil 1 12 can be heated and the pressure between the two rollers can be adjusted by well known means to provide the desired temperature, if applicable, and the pressure to concurrently weaken and melt stabilize the weft material 102 in a plurality of sites. The pattern calendering roller 110 is configured to have a circular cylindrical surface 14, and a plurality of protrusions or pattern elements 16 which extend outward from the surface 114. The protuberances 116 are arranged in a predetermined pattern with each protrusion 116 being configured and arranged to precipitate a weakened site, melt-stabilized in the weft material 102 to effect a predetermined pattern of weakened, melt-stabilized sites in the weft material 102. As shown in Figure 2, the Calendering roller with pattern 110 has a repeating pattern of protrusions 116 extending around the total circumference of surface 114. Alternately, the protuberances 116 may extend around a portion, or parts of the circumference of the surface 114. The protuberances 116 are preferably truncated conical shapes extending radially outwardly from the surface 114 and which have circular end-face surfaces 117. Although it is not intended in this way to limit the scope of the present invention to the protuberances of only this configuration. Other suitable shapes for the distal ends 117 include, but are not limited to, elliptical, square, rectangular, etc. The protuberances may also be designed such that at least a portion of the protuberances comprise at least one opening at their distal ends. In this case, at least a portion of the weakened regions of the weft material circumscribes a substantially less preheated region. Such a design can support the subsequent removal of the weft material from the weakened regions since the weft material to be removed then comprises a non-weakened part which potentially increases the overall integrity of the material to be removed. The roller 110 is finished in such a way that all of the end surfaces 117 are located in an imaginary right circular cylinder which is coaxial with respect to the roller rotation axis 110. The protuberances 116 are arranged in a predetermined regular pattern of rows and columns in the embodiment shown in Figure 2, although there is no attempt to limit the scope of the present invention to the protuberance pattern of only this configuration. The protuberances may be arranged in any predetermined pattern around the patterned calendering roller 110. In one embodiment of the present invention, the anvil roller 112 is a circular steel cylinder with a smooth surface. From the weakened means of the web 108, the web material 102 passes through the web material removal system 132. The web material removal means removes at least a portion of the web material comprised in the webs. weakened regions 202 of the weft material. In the case that the weakened regions circumscribe substantially less weakened regions, at least a portion of the non-weakened regions can be removed together with the weft material from the weakened regions. Referring now to Figure 3, the weft removal system may be a gas knife 134 that blows gas from a major top surface 180 of the weft material to the lower main surface 182. At least a portion of the weft material Included in the weakened regions 202 is removed when the gas flow is exerted. The blowing of gas through the weft material can be heated so as to support the removal of the weft material. The weft material removal system may further comprise a receptacle for the removed weft material preferably capable of filtering the weft material from the gas flow. Alternatively, the weft material removal system may comprise a sticky calendering roller and a smooth anvil roller. The surface of the calendering roll is treated in such a way that at least a portion of the weft material comprised in the weakened regions adheres to the surface of the calendering roll. Through the rotation of the calendering roller during the process, at least a portion of the weft material comprised in the weakened regions is removed from the weft material. The weft material removed can be removed from the surface of the calendering roll by a blade or the like. In another alternative embodiment of the present invention, the anvil roller 112 of the weft weakening means 108 has a sticky surface. Thusat least a portion of the weft material comprised in the weakened regions 202 adheres to the anvil roll 1 12 and is therefore removed from the weft material immediately after the selective weakening of the weft material. In another alternative embodiment of the apparatus of the present invention, the frame removal means may be integrated into the frame weakening means. In one embodiment, an air flow through the openings of the calendering roll can be generated such that the weakened weft material is substantially weakened with or immediately after weakening at least a portion of the weft material comprised in weakened regions, which is removed from the raster material. The air flow through the protuberances can be directed towards the weft material or it can be away from the weft material. Alternatively, the anvil roller of the weft weakening means may comprise openings for directing the flow of air to or from the weft material in order to remove at least a portion of the weft material comprised in the weakened regions. The openings in the protuberances of the calendering roller and in the respective anvil roller can also be used to generate an air flow selectively through at least a portion of the weakened regions. It is another aspect of the present invention to provide a disposable absorbent article comprising a selectively perforated weft material according to the present invention. As used herein, the term "absorbent article" refers to devices that absorb and contain exudates from the body, and, more specifically, refers to devices that are placed against or close to the wearer's body to absorb and contain the various exudates discharged from the body. The term "disposable" is used herein to describe absorbent articles that are not intended to be washed or restored or reused in another way as an absorbent article (ie, they are intended to be discarded after a simple use and, preferably, to be recycled, composted or otherwise disposed of in an environmentally compatible manner). A "unitary" absorbent article refers to absorbent articles that are formed of separate parts joined together to form a coordinated entity such that they do not require separate manipulated parts such as a support and separate liners. One embodiment of an absorbent article of the present invention is the unitary disposable absorbent article, diaper 20, shown in Figure 4. As used herein, the term "diaper" refers to an absorbent article generally worn by infants and incontinent persons who it is carried around the lower torso of the user. However, it should be understood that the present invention is also applicable to other absorbent articles such as incontinence briefs, incontinence undergarments, diaper liners and liners, feminine hygiene garments, training pants, and the like.

Figure 4 is a plan view of the diaper 20 of the present invention in its flattened state, without contracting (i.e., with the contraction induced by the elastic pulled outward) with parts of the structure that are cut to show more clearly the construction of the diaper 20 and with the portion of the diaper 20 that faces the wearer, the inner surface 40, giving the observer. As shown in Figure 4, the diaper 20 preferably comprises a containment assembly 22 comprising a topsheet 24 permeable to liquid; a back sheet 26 impermeable to the liquid attached to the upper sheet; and an absorbent core 28 positioned between the topsheet 24 and the backsheet 26. The diaper preferably further comprises elasticized side panels 30; Elastic leg cuffs 32; elasticated waistbands 34; and a fastening system 36 preferably comprising a pair of securing members 37 and a tie-down member (not shown). The diaper 20 is shown in Figure 4 to have an inner surface 40 (giving the observer in Figure 4) an outer surface 42 opposite the inner surface 40, a rear waist region 44, a front waist region 46 opposite to the rear waist region 44, a crotch region 48 positioned between the rear waist region 44 and the front waist region 46, and a periphery that is defined by the perimeter or outer edges of the diaper 20, in which the edges longitudinals are designated 50 and the end edges are designated 52. The inner surface 40 of the diaper 20 comprises that portion of the diaper 20 that is positioned adjacent the wearer's body during use (i.e., the inner surface 40 is generally formed by the minus a portion of the topsheet 24 and other components attached to the topsheet 24). The outer surface 42 comprises that part of the diaper 20 that is positioned remote from the wearer's body (i.e., the outer surface 42 is generally formed by at least a portion of the back sheet 26 and other components attached to the back sheet 26). As used herein, the term "attached" encompasses configurations by which one element is directly secured to the other element by fixing the element directly to the other element, and configurations by which the element is indirectly secured to the other element by fixing the element to a member or intermediate members, which in turn are fixed to the other element. The rear waist region 44 and the front waist region 46 extend from the edge edges 52 of the periphery to the crotch region 48. The diaper 20 also has two centerlines, a longitudinal centerline 90 and a center line. transverse 92. The term "longitudinal", as used herein, refers to an axis line or direction in the plane of the diaper 20 that is generally aligned with (eg, approximately parallel to) a vertical plane that divides a standing user in left and right halves when diaper 20 is used. The terms "transverse" and "lateral", as used herein, are interchangeable and refer to a line, axis or direction that is located within the diaper plane that is generally perpendicular to the longitudinal direction (which divides the user into frontal and posterior body halves). The containment assembly 22 of the diaper 20 is shown in Figure 4 as comprising the main frame (chassis) of the diaper 20. The containment assembly 22 comprises at least the topsheet 24, the backsheet 26 and the absorbent core 28. When the absorbent article comprises a separate support and liner, the containment assembly 22 generally comprises the support and the liner (i.e., the containment assembly 22 comprises one or more layers of material to define the support while the liner comprises a absorbent composite material such as a topsheet, a backsheet, and an absorbent core.) For the unitary absorbent articles, the containment assembly 22 comprises the main structure of the diaper with other features added to form the composite structure of the diaper.

Therefore, the containment assembly 22 for the diaper 20 generally comprises the topsheet 24, the backsheet 26, and the absorbent core 28. Figure 4 shows a preferred embodiment of the containment assembly 22 in which the topsheet 24 and the backsheet 26 have length and width dimensions generally greater than those of the absorbent core 28. The topsheet 24 and the backsheet 26 extend beyond the edges of the absorbent core 28 to thereby form the periphery of the diaper 20. Although can assemble in a variety of well-known configurations, the topsheet 24, the backsheet 26 and the absorbent core 28, illustrative configurations of the containment assembly are generally described in U.S. Patent No. 3,860,003 entitled "Portions. contractable laterals for disposable diaper "which was issued to Kenneth B. Buell on January 14, 1975; and in U.S. Patent No. 5,151, 092 entitled "Absorbent Article Characteristic of Dynamic Elastic Waistband Having a Resilient Resilient Biased Arrangement" which was issued to Kenneth B. Buell et al., September 29, 1992.; each of which are incorporated herein by reference. The absorbent core 28 can be any absorbent member which is generally compressible, conformable, non-irritating to the wearer's skin, and capable of absorbing and retaining liquids such as urine and other certain exudates from the body. As shown in Figure 4, the absorbent core 28 has a side that gives the garment, a side that faces the body, a pair of side edges, and a pair of waist edges. The absorbent core 28 can be manufactured in a wide variety of sizes and shapes (eg, rectangular, hourglass, T-shaped, asymmetric, etc.) and from a wide variety of liquid absorbent materials commonly used in disposable diapers and other absorbent articles such as crushed wood pulp, which is generally referred to as air felt. Examples of other suitable absorbent materials include acrylic cellulose wadding; meltblown polymers including coform; hardened, modified or cross-linked chemical cellulosic fibers; tissue including tissue wraps and tissue laminates; absorbent foams; absorbent sponges; superabsorbent polymers; gelling absorbent materials; or any equivalent material or combinations of materials. The configuration and construction of the absorbent core 28 may be varied (eg, the absorbent core 28 may have zones of varying gauge, a hydrophilic gradient, a superabsorbent gradient, or acquisition zones with lower average density and lower average basis weight, or may comprise one or more layers or structures). In addition, the size and absorbent capacity of the absorbent core 28 can also be varied to encompass users ranging from babies to adults. However, the total absorbent capacity of the absorbent core 28 must be compatible with the design load and intended use of the diaper 20. One embodiment of the diaper 20 has an asymmetric absorbent core 28, in the form of a modified T, having ears on the back. frontal waist region but a generally rectangular shape in the rear waist region. Exemplary absorbent structures for use as the absorbent core 28 of the present invention which have achieved wide acceptance and commercial success are described in U.S. Patent No. 4,610,678 entitled "High Density Absorbing Structures" issued to Weisman et al. September 1986; U.S. Patent No. 4,673,402 entitled "Absorbent articles with cores in double layers" issued to Weisman et al. on June 16, 1987; U.S. Patent No. 4,888,231 entitled "Absorbent Core Having A Dust Cap" issued to Angstadt on December 19, 1989; and in U.S. Patent No. 4,834,735 entitled "High density absorbent members having acquisition zones with lower density and lower basis weight" issued to Alemany et al. on May 30, 1989. The absorbent core may further comprise the dual core system containing a core of acquisition / distribution of chemically hardened fibers placed on an absorbent storage core as detailed in U.S. Patent No. 5,234,423 entitled "Absorbing article with characteristic elastic waist and improved absorbency" issued to Alemany et al. On August 10, 1993; and in U.S. Patent No. 5,147,345, entitled "High Efficiency Absorbent Articles for Incontinence Management" issued to Young La Von and Taylor on September 15, 1992. All of these patents will be listed here by reference. The backsheet 26 is positioned adjacent the garment-facing surface of the absorbent core 28 and is preferably attached thereto by attachment means (not shown) such as those well known in the art. For example, the backsheet 26 can be secured to the absorbent core 28 by a continuous uniform adhesive layer, a patterned adhesive layer, or an array of separate lines, coils, or spots of adhesive. The adhesives that have been found to be satisfactory are manufactured by H. B. Fuller Company of St. Paul, Minn, and marketed as HL-1258. An example of a suitable attachment means comprising an open pattern web of adhesive filaments is disclosed in U.S. Patent No. 4,573,986 entitled "Disposable garment for waste containment" which was issued to Minetola et al. March 1986. Other suitable joining means comprising several lines of adhesive filaments twisted in a spiral pattern are illustrated by the apparatus and methods shown in U.S. Patent No. 3,911,173 issued to Sprague, Jr. October 7, 1975; U.S. Patent No. 4,785,996 issued to Ziecker, and others on November 22, 1978; and in U.S. Patent No. 4,842,666 issued to Werenicz on June 27, 1989. Each of these patents will be listed here by reference. Alternatively, the joining means may comprise thermal joints, pressure joints, ultrasonic joints, mechanical dynamic joints, or any other means of joining or combinations of these joining means as is known in the art. Also contemplated are embodiments of the present invention wherein the absorbent core is not attached to the backsheet 26, the topsheet 24, or both in order to provide greater extensibility in the front waist regions 46 and in the region of back waist 44. Backsheet 26 is impervious to liquids (eg, urine) and is preferably manufactured from a thin plastic film, although other flexible liquid impervious materials may also be used. As used herein, the term "flexible" refers to materials that are docile and that will easily conform to the figure and general outline of the human body. The backsheet 26 prevents the exudates absorbed and contained in the absorbent core 28 from wetting the articles that are in contact with the diaper 20 such as sheets and undergarments, however, the backsheet 26 may allow the vapors to escape from the absorbent core. 28 (that is, it is breathable). In this manner, the backsheet 26 preferably comprises a polymeric film such as polyethylene or polypropylene thermoplastic film. A suitable material for the backsheet 26 is a thermoplastic film having a thickness of about 0.012 mm to about 0.015 mm. The topsheet 24 is positioned adjacent the surface that faces the absorbent core 28 and is preferably attached thereto and the backsheet 26 by attachment means (not shown) such as those well known in the art. Suitable attachment means were described with respect to attachment of the backsheet 26 to the absorbent core 28. In a preferred embodiment of the present invention, the upper sheet 24 and the back sheet 26 are directly joined together at the periphery of the diaper and are indirectly joined together by attaching them directly to the absorbent core 28 by the joining means (not shown).

The topsheet 24 is preferably docile, gentle in feel, and non-irritating to the wearer's skin. In addition, the topsheet is preferably permeable to the liquid allowing liquids (eg, urine) to easily penetrate through its thickness. A suitable top sheet 24 can be manufactured from the apertured weft material according to the present invention. The diaper 20 preferably further comprises elasticized leg cuffs 32 to provide fluid containment and other exudates of the improved body. Each elastic leg fold 32 may comprise several different embodiments to reduce leakage of the exudates of the leg in the regions of the leg. (The leg fold may be and is sometimes also referred to as leg bands, side flaps, barrier folds, or elastic folds.) U.S. Patent No. 3,860,003 describes a disposable diaper that provides a collapsible leg opening. having a lateral flap and one or more elastic members to provide an elasticized leg fold (packing fold). U.S. Patent No. 4,909,803 entitled "Disposable Absorbent Article Having Elasticized Fins" issued to Aziz et al. On March 20, 1990, discloses a disposable diaper having "upright" elasticated fins (barrier folds) to improve the containment of leg regions. U.S. Patent No. 4,695,278 entitled "Absorbent Article with Double Folds" issued to Lawson on September 23, 1987, discloses a disposable diaper having double folds including a gusset fold and a barrier fold. U.S. Patent No. 4,704,115 entitled "Disposable Garment for Containment of Waste" issued to Buell on November 3, 1987, discloses a disposable diaper or incontinence garment having sidewall leakage protection channels configured to contain free liquids inside the garment. Each of these patents will be listed here by reference. Although each leg elasticated fold 32 can be configured to be similar to any of the leg bands, side flaps, barrier folds, or elastic folds described above, it is preferred that each leg elasticated fold 32 comprises at least one internal fold. barrier comprising a barrier fin and a separation element as described in the aforementioned US Pat. No. 4,909,803. In a preferred embodiment, the elasticized leg fold 32 further comprises a resilient gusset of packing with one or more elastic threads, positioned outside the barrier fold as described in the aforementioned US Patent No. 4,695,278. The diaper 20 preferably further comprises an elasticated waistband 34 which provides for improved fit and containment. The elastic waistband 34 is that portion or area of the diaper 20 that is intended to expand and contract elastically to dynamically adjust the wearer's waist. The elasticized waistband 34 preferably extends longitudinally outward from at least one of the waist edges of the absorbent core 28 and generally forms at least a portion of the end edge of the diaper 20. The disposable diapers are generally constructed to have two elasticated waistbands, one placed in the back waist region and one placed in the front waist region, although you can build diapers with a simple elasticated waistband. In addition, although the elasticized waistband 34 or any of its constituent elements may comprise a separate element secured to the diaper 20, the elasticized waistband 34 may be constructed as an extension of other diaper elements such as the backsheet 26 or the upper sheet 24, preferably both of the backsheet 26 and the topsheet 24. The elasticized waistband 34 can be constructed in a number of different configurations including those described in U.S. Patent No. 4,515,595 entitled "Disposable diapers with elastically shrinkable waistbands" issued to Kievit et al. On May 7, 1985 and in the aforementioned United States Patent No. 5,151,092 issued to Buell.; each of these references being incorporated herein by reference. In a preferred embodiment, the diaper 20 also comprises elasticized side panels 30 disposed in the rear waist region 44. (As used herein, the term "disposed" is used to imply that a diaper element or elements is formed ( attached and placed) in a particular location or position as a unitary structure with other diaper elements or as a separate element attached to another diaper element.) Elasticized side panels 30 provide an elastically extensible feature that provides greater comfort and contour adjustment comfortably initially adjusting the diaper to the wearer and holding this adjustment throughout the time of use long after the diaper is loaded with exudates since the elasticized side panels will allow the sides of the diaper to expand and contract. The elasticized side panels 30 further provide the most effective application of the diaper 20 since even if the diapering person pulls an elasticized side panel 30 farther than the other during the application (asymmetrically), the diaper 20"self- will adjust "during use. Although the diaper 20 of the present invention preferably has the elasticized side panels 30 arranged in the rear waist region 44, alternatively, the diaper 20 can also be provided with elasticized side panels disposed in the front waist region 46 and the region back waist 44. Although elasticized side panels 30 can be constructed in a number of configurations, examples of diapers with elasticized side panels are disclosed in U.S. Patent No. 4,857,067 entitled "Disposable diaper having straightened ears" issued. to Wood, and others on August 15, 1989; U.S. Patent No. 4,381, 781 issued to Sciaraffa, and others on May 3, 1983; U.S. Patent No. 4,938,753 issued to Van Gompel, and others on July 3, 1990; and in U.S. Patent No. 5,151,092 issued to Buell et al. on September 29, 1992; each of which are incorporated herein by reference. Elastic materials suitable for use as the elastified side panels include elastomeric foams, synthetic or natural rubber, natural synthetic rubber foams, elastomeric films, elastomeric canvas, woven or non-woven elastomeric wefts, elastomeric composite materials such as elastomeric non-woven laminates, or Similar. The diaper 20 also comprises a fastening system 36 which forms a lateral closure which maintains the rear waist region 44 and the front waist region 46 in an overlapping configuration such that lateral stresses are maintained around the circumference of the diaper to keep the diaper on the wearer. Illustrative fastening systems are disclosed in U.S. Patent No. 4,869,724 issued to Scripps on September 26, 1989; U.S. Patent No. 4,846,815 issued to Scripps on July 1, 1989; U.S. Patent No. 4,894,060 issued to Nestegard on January 16, 1990; U.S. Patent No. 4,946,527 issued to Battrell on August 7, 1990; U.S. Patent No. 3,848,594 issued to Buell on November 29, 1974; and in U.S. Patent No. 4,662,875 issued to Hirotsu and Robertson on May 5, 1987. Each of these patents will be listed here by reference. The selectively perforated weft material of the present invention can also be used as a topsheet in other disposable absorbent articles such as, for example, incontinence briefs, training pants, feminine hygiene garments and the like. The selectively perforated weft material may also be used in other parts of a disposable absorbent article such as, for example, as an acquisition layer placed between the topsheet and the absorbent core, as part of the absorbent core, or as portions of others. components of the disposable absorbent article.

Claims (10)

1. A process for selectively perforating a weft material, the process comprising the steps of: providing a weft material selectively weakening a plurality of regions of the weft material by removing at least a portion of the weft material comprised within the regions weakened using a technique selected from the group of: gas-blown, tear.

2. A process for selectively perforating a weft material according to claim 1, wherein the step of selectively weakening a plurality of regions of said weft material comprises a step of selectively heating said plurality of regions.

3. A process for selectively perforating a weft material according to claim 2, wherein said regions are heated to a temperature below the melting point of the weft material.

A process for selectively perforating a weft material according to claim 1, said weft having a major upper surface and a major lower surface, wherein said step of removing the weft material comprises blowing gas through the weft material from the main top surface to the main bottom surface in order to drill at least a portion of the weakened regions.

A process for selectively perforating a weft material according to claim 1, wherein at least a portion of the weakened regions circumscribes a substantially less weakened region.

6. A process for selectively perforating a weft material according to claim 1, wherein said weft material is a nonwoven material.

7. An apparatus for selectively piercing a weft material, said apparatus comprising: a weft material supplying means a weft weakening means for selectively weakening a plurality of regions of said weft material a weft removal means to remove at least a part of the web material comprised in said weakened regions.

An apparatus for selectively piercing a weft material according to claim 7, wherein said weft weakening means comprises a calendering roll and an anvil roll, the surface of the calendering roll comprising a plurality of protuberances.

An apparatus for selectively piercing a weft material according to claim 9, wherein at least a portion of the protuberances comprises at least one opening in its distal surface.

10. An absorbent article comprising the selectively perforated weft material manufactured according to the process of claim 1.