MXPA01003819A - Method for forming an apertured web - Google Patents

Abstract

A method for forming an apertured web which may be used as a topsheet on a disposable absorbent article, such as a diaper. The web (240) is fed in as machine direction through a first nip (250) formed by a pair of rollers one of the rollers having a smooth outer surface and the other roller having an outer surface with a plurality of projections extending from it's outer surface. At least one of the rollers of the first nip (250) is heated. The first nip (250) apertures the web with a plurality of apertures each having a fused perimeter. The web (240) is then cooled to solidify the fused perimeter of the apertures. The web (240) is then fed through a second nip (280) formed by a pair of rollers to break the solidified fused perimeter of the apertures. One of the rollers of the second nip (280) has an outer surface with a plurality of grooves.

Description

METHOD TO FORM A FRAME WITH OPENINGS FIELD OF THE INVENTION This invention relates to a method for forming a screen with openings, and more particularly to a method for forming a screen with openings suitable for use as a top sheet in a disposable absorbent article.

BACKGROUND OF THE INVENTION Disposable absorbent articles such as diapers and adult incontinence products are well known in the art. These disposable absorbent articles collect and retain the urine and fecal material deposited thereon by the user. To date, most attempts in the art to handle urine and fecal material collected and retained within the disposable absorbent article have been directed to handle urine. Tackling the fecal material collected by the disposable absorbent article is simply more difficult than dealing with or treating with urine, due to the complex rheology of the low viscosity faecal material. Illustrative of the prior art for urine handling are several attempts to provide disposable absorbent articles having a first topsheet that faces toward and is in contact with the wearer's body, and a secondary topsheet beneath the first topsheet; which either absorbs urine, or transfers the urine to an underlying core for storage until the user's disposable absorbent article is removed.

Typically, the first top sheet and the second top sheet have different material properties. The secondary upper sheet may have a smaller pore size than the first upper sheet, to assist in the transfer of urine through the upper sheet. The first top sheet can be hydrophobic and more resilient when wetted than the secondary top sheet, in order to pass the fluids through the first top sheet towards the secondary top sheet. In yet another attempt in the prior art, the disposable absorbent article has a first topsheet, a topsheet and a core. The secondary topsheet consists essentially of hydrophilic fibers blown in the molten state and has a pore size greater than the pore size of the core. This arrangement allegedly allows the secondary upper sheet to rapidly receive multiple discharges of liquid and distribute the liquid within the X-Y plane before absorption by the core. In yet another attempt, the improved vertical capillary action capacity for urine has been allegedly achieved by using inflated cellulose fibers which are free of a surface finish or interlocked with other fibers. In another attempt in the prior art, the absorbent core suitable for acquiring and containing liquids such as urine in a particularly effective and efficient manner comprises multiple layers. The first layer, which is closer to the user, comprises a fibrous hydrophilic material and has a relatively lower average density acquisition zone than other portions of this layer, in order to quickly acquire the discharged liquids. Beneath the first layer is a liquid handling layer comprising a high density, low density, resilient void material that is insensitive to moisture in order to rapidly acquire the liquid discharges to itself through an acquisition zone and distribute these liquids through the liquid handling layer to a storage layer. The storage layer comprises a combination of fibrous material and discrete particles of gelling absorbent material, and allows the liquid handling layer to be drained of the liquids it has acquired, such that the liquid handling layer can have a capacity of enough to acquire and distribute subsequent loads of liquids. Examples of these attempts in the prior art include U.S. Patent Nos. 4,047,531 issued September 13, 1977 to Karami.; 4,798,603 issued January 17, 1989 to Meyer et al .; 5,037,409 issued August 6, 1991 to Chen et al .; 5,124,197 issued June 23, 1992 to Bemardin et al .; and 5,134,007 issued on July 28, 1992 to Reising and others. Of course, gelling absorbent materials are also well known in the prior art for their ability to handle urine. The gelling absorbent materials are polymeric materials capable of absorbing large quantities of fluids, such as urine, and retaining such fluids absorbed under moderate pressure. The effectiveness of the gelling absorbent materials is very dependent on the shape, placement and percentage by weight of the gelling absorbent materials that are incorporated in the core of the disposable absorbent article. Recent attempts have been made in the art to provide gelling absorbent materials that have the ability to swell against pressure. These teachings are intended to provide the advantage that the gelling absorbent materials absorb fluid under actual pressures exerted by the body during use.

Still other teachings in the art provide gelling absorbent materials that have a particular free swelling rate and absorbency under pressure. The intended advantages of such gelling absorbent materials are smaller bulk and volume with approximately the same absorbent capacity, the ability to quickly absorb a discharged liquid under pressures typically encountered during use, and the ability to retain the liquid absorbed under pressures typically encountered during the use. In another prior attempt, U.S. Patent No. 4,704,112 issued to Suzuki et al. Discloses a cover comprising a nonwoven fabric having two different layers of different fiber compositions. The upper layer has a pattern of openings therein and is made from hydrophobic fibers and the lower layer has no openings and is made from hydrophilic fibers. Examples of these attempts in the prior art include U.S. Patent Nos. 5,147,343 issued September 15, 1992 to Kellenberger and 5,149,335 issued September 22, 1992 to Kellenberger et al. However, all of these attempts to handle the urine do little, if anything, to improve the handling of the low viscosity faecal material that may also be present in the disposable absorbent article. Attempts to address the fecal material include providing a first top sheet that closely conforms to the user and has an opening. The opening is hopefully recorded with the opening of the anus, so that the fecal material passes through it into a hollow space.

The first top sheet may comprise several elastic panels so as to closely conform to the wearer's skin, and / or may have linear elastic filaments. Improvements have been made in this area of the prior art, such as optimizing the material properties of the first top sheet. Such optimization makes the first top sheet more comfortable for the user and allows a simple disposable absorbent article to fit a larger size range of users. Still other attempts have been made in this area of the prior art to provide an absorbent core with a hole therein, in order to receive the fecal material. The hole may be flattened by the poles, so that it is larger and narrower than the opening in the first top sheet, or it may be diamond-shaped. The hole in the core may be disposed below an opening having elastic strips around its edge. Improvements to this genre of disposable absorbent articles of the prior art also include the addition of spacers. The spacers can be interposed between the first top sheet and the core, in order to ensure that a hollow space is present to receive the fecal material. Still other attempts have been made in this prior art art to provide barriers that limit movement of the fecal material to particular portions of the disposable absorbent article. The barriers limit the contact of fecal material to a smaller portion of the user's skin, than a comparable disposable absorbent article that has no barriers. Still other attempts in the prior art provide barrier cuffs for the leg which are raised from the plane of the topsheet. The barrier cuffs for the leg prevent the fecal material from deflecting or branching around the perimeter of the disposable absorbent article. Examples of these attempts to handle fecal material include U.S. Patent No. 4,892,536 issued January 9, 1990 to DesMarais et al .; U.S. Patent No. 4,909,803 issued March 20, 1990 to Aziz et al .; U.S. Patent No. 4,968,312 issued November 6, 1990 to Khan; the commonly assigned patent of the United States No. 4,990,147 issued February 5, 1991 to Freeland, the commonly assigned U.S. Patent No. 5,037,416 issued August 6, 1991 to Alien et al .; U.S. Patent No. 5,062,840 issued November 5, 1991 to Holt et al .; the commonly assigned United States Patent No. 5,171, 236 issued December 15, 1992 to Dreier et al .; and the European patent application 0,355,740 A2 published on February 28, 1990 to Enloe.

However, none of these attempts to handle fecal material solve the problem of low viscosity faecal material that is predominantly prevalent in younger children, particularly those who are breast fed. Fecal low viscosity material easily migrates into the disposable absorbent article under the influence of gravity and movement or pressure by the user. The migration of fecal material frequently moves towards the perimeter of the disposable absorbent article, increasing the probability of leakage. The migration of fecal material also smeagainst the user's skin, making cleaning more difficult. In order to clean the user, the caregiver should rub the entire area of the skin that has found the fecal material and typically has to deal with a relatively large stained area. An attempt in the art to handle low viscosity fecal material is found in U.S. Patent Application Serial No. 08 / 076,713 filed June 11, 1993 in the name of Roe. This application is a disposable absorbent article having a first top sheet with a high penetration through the top sheet that is on a secondary top sheet having less penetration through the top sheet.

BRIEF DESCRIPTION OF THE INVENTION The invention is a method for forming a screen with openings which can be used as a top sheet in a disposable absorbent article, such as a diaper. The web is fed in a machine direction through a first grip space formed by a pair of rollers, one of the rollers having a smooth external surface and the other roller having an external surface with a plurality of projections extending from its external surface. At least one of the rollers forming the gripping space is heated, preferably both rollers are heated. As the weft passes through the first grip space a plurality of openings are created each having a molten perimeter. The weft is cooled to solidify the molten perimeter of the openings. The web is then fed through a second gripping space formed by a pair of rollers to break the solidified molten perimeter of the openings. One of the rollers of the second gripping space has an outer surface comprising a plurality of grooves. The weft can be fed through a third gripping space formed by a pair of rollers to further break the molten perimeter of the openings. One of the rollers of the third gripping space has an external surface comprising a plurality of grooves.

BRIEF DESCRIPTION OF THE DRAWINGS Although the description concludes with the claims that differently claim and claim the present invention, it is believed that it will be better understood by the following drawings taken in combination with the accompanying description, wherein similar components are given with the same number reference. Figure 1 is a top plan view, shown partially in section, of a disposable diaper having an upper sheet constructed of the apertured weft of the present invention. Figure 2 is a cross-sectional view of the upper sheet of the apertured weft shown in Figure 1. Figure 3 is a top plan view of a disposable diaper having a top sheet constructed of another embodiment of the weft pattern. the present invention.

Figure 4 is a simplified schematic illustration of a process for forming the apertured web of the present invention. Figure 5 is an enlarged illustration of the aerial plan view of the slotted roller of Figure 4. Figure 6 is a simplified schematic illustration of another process for forming the apertured screen of the present invention. Figure 7 is an enlarged illustration of the aerial plan view of the grooved roller of the third gripping space of Figure 6. Figure 8 is a simplified schematic illustration of another process for forming the apertured screen of the present invention.

DETAILED DESCRIPTION OF THE 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 user'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 otherwise restored or reused as an absorbent article (ie, they are intended to be discarded after a single use and preferably , to be recycled, composted or otherwise disposed of in an environmentally compatible way). 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 fastener and separate liners.

An absorbent article utilizing the apertured web of the present invention as a topsheet thereon is the unitary disposable absorbent article, diaper 20, shown in Figure 1. As used herein, the term "diaper" refers to a absorbent article generally worn by incontinent babies and adults and carried around the user's lower torso. The web of the present invention can also be used as a topsheet in other absorbent articles such as incontinence briefs, incontinence undergarments, absorbent inserts, diaper liners and liners, feminine hygiene garments, and the like. Although the present invention will be described within the context of providing a suitable web for use as a topsheet in a disposable absorbent article, the present invention is thus not limited to such an application. The description of the screen with openings and its use as a top sheet will allow one skilled in the art to easily adapt the invention to other devices and for other uses. Figure 1 is a plan view of the diaper 20 of the invention present in its flattened state, without contracting (i.e., with the contraction induced by the elastic pulled outwards) 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 toward or is in contact with the wearer, the inner surface facing the observer. As shown in Figure 1, the diaper 20 preferably comprises a topsheet 24 permeable to liquid; a back sheet 26 impervious to the liquid attached to the topsheet 24; and an absorbent core 28 between the topsheet 24 and the backsheet 26. The diaper 20 may further comprise elasticized side panels (not shown); elastic leg cuffs (not shown); an elastic waist feature (not shown); and a fastener system with generally multiple tape tabs designated 36. The diaper 20 is shown in Figure 1 to have a first waist region 27 juxtaposed with the front of the wearer while the diaper 20 is worn, a second region of waist 29 opposite the first waist region 27 and juxtaposed with the user's back while the diaper is worn 20, a crotch region 31 positioned between the first waist region 27 and the second waist region 29, and a periphery that is defined by the outer edges of the diaper 20 in which the longitudinal edges 33 are designated and are designated the edges of the diaphragm. end 35. The inner surface of the diaper 20 comprises that part of the diaper 20 that is adjacent to the wearer's body during use (i.e., the inner surface is generally formed by at least a portion of the topsheet 24 and other components attached to it. the upper sheet 24). The outer surface comprises that part of the diaper 20 that is positioned away from the wearer's body (i.e., the outer surface is generally formed by at least a portion of the back sheet 26 and other components attached to the back sheet 26) during use. Figure 1 shows a modality of the diaper 20 in which the topsheet 24 and the backsheet have dimensions of length and width 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. While the upper sheet 24, the back sheet 26 and the absorbent core 28 can be assembled in a variety of well-known configurations, the preferred diaper configurations are generally described in the patent. from US No. 3,860,003 entitled "Shrinkable side portions for disposable diaper" which was issued to Kenneth B. Buell on January 14, 1975; and in U.S. Patent No. 5,151,092"Absorbent article having dynamic elastic waist feature having a predisposed resilient flexure joint" issued to Kenneth B. Buell et al. on September 29, 1992; each of which is incorporated herein by reference. The absorbent core 28 may be any absorbent means that is generally compressible, capable of shaping, 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 1, the absorbent core 28 has a garment surface, a body surface, side edges, and 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 crushed cellulose wadding; meltblown polymers including coform; chemically hardened, modified or interlaced 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 also be varied (eg, the absorbent core 28 may have varying gauge zones, a hydrophilic gradient, a superabsorbent gradient, or acquisition zones of lower average density or lower average basis weight; understand one or more layers or structures). However, the total absorbent capacity of the absorbent core 28 must be compatible with the design load and intended use of the diaper 20. In addition, the size and absorbent capacity of the absorbent core 28 can be varied to encompass users ranging from babies to adults .

Exemplary absorbent structures for use as the absorbent core 28 are described in U.S. Patent No. 4,610,678 entitled "High Density Absorbing Structures" issued to Weisman et al. On September 9, 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 of lower density and lower basis weight" issued to Alemany et al. on May 30, 1989. Each of these patents is incorporated here by reference. The backsheet 26 is positioned adjacent the garment surface of the absorbent core 28 and is preferably attached thereto by attachment or attachment means (not shown) such as those well known in the art. As used here, the term "joined" 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 those that instead are fixed to the other element. 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, Minnesota and marketed as HL-1258. The fastening means will preferably comprise an open-pattern network of filaments of adhesives as disclosed in U.S. Patent No. 4,574,986 entitled "Disposable Garment for Containment of Waste" which was issued to Minetola et al. On March 4, 1986, most preferably several lines of adhesive filaments twisted in a spiral pattern as illustrated by the apparatus and methods shown in U.S. Patent No. 3,911,173 issued to Sprague, Jr. on October 7, 1975; U.S. Patent No. 4,785,996 issued to Ziecker et al. on November 22, 1978; and in U.S. Patent No. 4,842,666 issued to Werenics on June 27, 1989. Each of these patents is incorporated herein by reference. Alternatively, the attachment means may comprise thermal joints, pressure joints, ultrasonic joints, mechanical dynamic joints, or any other suitable means of attachment or combinations of these fixation means as are known in the art. The 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 here, "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 within the absorbent core 28 from wetting the articles that are in contact with the diaper 20 such as sheets and undergarments. The backsheet 26 can thus comprise a woven or non-woven material, polymeric films such as polyethylene or polypropylene thermoplastic films, or composite materials such as a film-coated nonwoven material. Preferably, the backsheet 26 is a thermoplastic film having a thickness of about 0.012 mm to about 0.051 mm. Particularly preferred materials for the backsheet 26 include the RR8220 blown films and the RR5475 cast films as manufactured by Tredegar Industries, Inc. of Terre Haute, Indiana. The backsheet 26 is preferably finished in highlight and / or dull to provide a more fabric-like appearance. In addition, the backsheet 26 can allow the vapors of the absorbent core 28 to escape (ie, be breathable) while still preventing the exudates from passing through the backsheet 26. The topsheet 24 is juxtaposed with, but not necessarily adjacent to the body surface of the absorbent core 28, and is preferably attached to the backsheet 26 or the absorbent core 28 by means such as those well known in the art. Suitable fixation means were described above with respect to the attachment of the backsheet 26 to the absorbent core 28. In a preferred embodiment of the present invention, the topsheet 24 and the backsheet 26 are directly joined together at the periphery of the diaper. Referring now to Figures 1 and 2, the topsheet 24 comprises a weft 40 constructed of a liquid-permeable material. The weft 40 is docile, soft feeling, and non-irritating to the wearer's skin. The web 40 is preferably a nonwoven web permeable to liquid. The non-woven web is a fibrous material formed from meltable polymeric fibers or filaments. The nonwoven web can be formed from any of the following polymers: polyamides, polypropylene, polypropylene copolymers, two components, polyethylene, polyethylene terephthalate, combinations thereof, and the like. Suitable materials include dry-laid and carded webs, random and air-laid webs, spin-linked webs, meltblown webs, spin-linked webs, and webs bonded by air or calendering. Alternatively, the nonwoven web can be joined with latex via saturation bonding, gravure printing, screen printing, spraying or foam bonding. Still further, the nonwoven web can be joined with combinations of the prior art, such as latex bonded or calendered webs or other suitable combinations. The fibers can be of various sizes with fibers having a denier of between about 1 and preferably 18. The web 40 preferably has a basis weight of about 5 gm2 to 100 gm2, more preferably about 5 gm2 to about 60 gm2. The web 40 preferably has a caliper from about 0.1 mm to about 5.00 mm, and more preferably from about 0.1 mm to about 2.0 mm. The weft 40 has a plurality of openings 46 with an effective opening size of at least 0.2 square millimeters, more preferably, the plurality of openings have an effective opening size of at least 0.5 square millimeters, even more preferably, the plurality of apertures have an effective aperture size of at least 1.0 square millimeters, and most preferably, the plurality of apertures have an effective aperture size of at least 2.0 square millimeters. Effective openings are those that have a gray level of 18 or less on a standard gray level scale of 0-255, below the image acquisition parameters described below. Screen 40 preferably has an effective open area of at least percent, more preferably the screen 40 has an effective open area of at least 15 percent, even more preferably, the screen 40 has an effective open area of at least 20 percent, and most preferably the screen 40 has an area effective open of at least 25 percent. The effective aperture size and the effective open area are determined by the following procedure using the image analysis described below. The process has three main steps: image acquisition, that is, obtaining representative images of the areas on the surface of the frame 40; measurement of the image, that is, measuring the percentage of the open area of an image and of the individual openings and their perimeters; and data analysis, that is, export the percentage of open area, the individual opening area, and the perimeter measurements to a spreadsheet where the frequency distributions are made, the sum of the area distributions, and are calculated the hydraulic radios. An image analysis system is used that has a frame taking card, a microscope, a camera and an image analysis software. A DT2855 Model Taker Card available from Data Translation of Marlboro, Mass. A VH5900 monitor microscope, a video camera, is also provided and used, which has VH50 lenses with a contact lighting head available from Keyence Company of Fair Lawn, N.J., to acquire an image that will be stored in the computer file. The Keyence microscope acquires the image and the picture taking card converts the analog signal of this image into the digital format readable by the computer. The image is saved in the computer file and measured using the appropriate software such as the Optimus image analysis software, version 3.1, available from BioScan Company of Edmaons, Wash. In order to use the optimal image analysis software, the computer must have the software Windows, version 3.0 or later, available from Microsoft Corporation of Redmond, Wash. And also have a CPU at least equivalent to the Intel 80386. Any suitable portable personal computer can be used, with a 486 DX33 type PC that has been found to be particularly suitable. The images that are saved and are recalled from the file were displayed on a Sony monitor Trinitron model PVM-1343MO with a final amplification of deployment of approximately 50 times. The image acquisition step, highlighted above, requires 10 different regions from a sample of representative material to be tested. Each region is rectangular, measuring approximately 5.8 mm by 4.2 mm.

The sample is placed on a black mat board to increase the contrast between the openings and the portion of the sample which defines the openings. The average gray level and the standard deviation of the black mat table were 16 and 4, respectively. The images are acquired with the room lights off using the microscope with the Keyence monitor mounted on a copying platform directly above the sample. The Keyence light source illuminating the sample is adjusted and monitored with the Optimas software to measure the average gray level and the standard deviation of a 0.3 density prism on a Kodak gray scale available from Eastman Kodak Company of Rochester, New York The control of the Keyence light source is adjusted in such a way that the average gray level of the illuminated prism is 111 ± 1 and the standard deviation is 10 ± 1. All the images were acquired during a simple time period, and the source of light Keyence is monitored by measuring the average gray level and the standard deviation of the prism throughout the image acquisition process. When measuring an individual opening, only the size of the effective opening is of interest. The measurement of the effective aperture size quantifies the size of the aperture intended to contribute to the porosity of the material, and accounts for the contributions of the fibers and fiber bundles passing through an area intended to be an aperture. An effective aperture is any hole through the material that has a gray level less than or equal to 18 using the image acquisition parameters as described herein. In this way, an attempted opening can be divided into the plural effective openings by the transverse fibers. The image analysis software is calibrated in millimeters using a standard image acquired from the images in the sample. A filter that averages 3 by 3 pixels is found in the Optima 3.1 image menu for each image saved to reduce noise. The openings are detected within the gray level range from 0 to 18. An aperture that is not fully contained within the viewing area of 5.8 by 4.2 is not considered within the individual area and perimeter measurements. Therefore, the averages and distributions of the area and the perimeter are not affected by the openings that are not completely contained within the field of view. However, individual openings that can not be completely seen in the image are included in the calculation of the percentage of open area. This difference occurs because the percentage of open area is simply the image of pixel proportions from 0 to 18 with respect to the total number of pixels in the image. Areas that have a gray level of 19 or higher were not counted in the calculation of the open area. The percentage of the open area for the average of 10 images for each material is measured using the Optima image analysis software. The percentage of open area is defined as the proportion of the number of pixels that have a gray level from 0 to 18 with respect to the total number of pixels for the image. The percentage of the open area is measured for each image representing a particular region of a sample.

The percentage of open area from each of the 10 individual images is then averaged to produce a percentage of open area for the total sample. The data analysis is conducted by an Excel spreadsheet, also available from Microsoft Corporation of Redmond, Washington. The Excel spreadsheet organized the percentage of open area, the measurements of the opening area, and the perimeter of the opening, obtained from the Optimas software. The average and standard deviations of the sample, the size and frequency of distribution of the individual opening areas and the calculations of the hydraulic radius (area divided by the perimeter) for the individual openings are obtained using the spreadsheet. The distributions and the individual area of the opening are also calculated using the Excel spreadsheet. The openings are classified into sections of certain size ranges. The number of opening areas that fall in certain ranges of interest size is also determined as the sum of the areas within each range. The ranges are established in increments of 0.05 square millimeters. These areas are expressed as a percentage of the total open area of the sample. The frequency and the sum of the area distributions are obtained by combining the individual measurements of the aperture from all 10 images for each sample. The openings 46 in the weft 40 may vary in size, shape and pattern. Examples of some possible forms include but are not limited to circular, square, rectangular, oval, triangular, dog bone, star, flattened by poles, etc. The openings 46 can be arranged in either a systematic, uniform or random pattern. A systematic pattern with similarly sized openings is preferred. Referring now to Figure 3, the topsheet 124 in the diaper 120 comprises the apertured weft 140. As can be seen in Figure 3, the weft 140 is only perforated in the rear or rear waist region 129 of the diaper 120. The weft 140 may be perforated in any suitable manner to provide the desired benefits in certain portions or regions of the diaper 120. For example, the weft 140 may be perforated in only the crotch region 131 or only in the front waist region 127, any combination of the two regions, portions of any region, or portions of several regions. Referring now to Figure 4 there is shown a schematic illustration of a process 200 for forming the apertured weft of the present invention. A material 240 is unwound from a supply roll 210 and travels in the direction indicated by the arrows associated therewith, ie, in the machine direction, as the supply roll 210 rotates in the direction indicated by the associated arrows with the same. Instead of being unrolled from a supply roll the material can be directly fed from a forming apparatus, for example, a carding apparatus, a carding and calendering apparatus, a spinning linking apparatus, a spinning linking apparatus and calendering, a meltblowing apparatus, a meltblown and calendered blowing apparatus, to the first gripping space 250. The framing 240 is fed through the first gripping space 250 of the drilling apparatus 252 formed by the rollers. 254 and 260. The roller 260 has a smooth outer surface 262. The roller 260 is preferably constructed of steel. The roller 260 can be constructed of other materials, for example, rubber. The roller 254 includes a plurality of projections 258 that extend around its outer surface 256. The roller 254 is preferably constructed of steel. The rollers 254 and 260 preferably rotate at the same speed. Although at least one of the rollers 254 and 260 is heated, preferably, both rollers 254 and 260 are heated. Preferably, the roller 254 is heated to have a higher temperature than the roller 260. As the web 240 passes through the first gripping space 250 it is perforated. As it is perforated the weft is heated above its melting point in such a way that at least a portion of the perimeter of the openings is melted. After the web 240 has been pierced by the apparatus 252, the web 240 is then cooled to immobilize the web after leaving the apparatus 252. In Fig. 4, the web 240 is shown to be cooled by blowing cool air over the web 240 from the fan 270. Of course, other known techniques for cooling the web 240 can be used. The cooling of the web also solidifies the molten material that extends around the perimeter of the openings. After cooling, the apertured web 240 is fed through the second grip space 280 formed by the rollers 282 and 284. The rollers 282 and 284 preferably rotate at the same speed. The rollers 282 and 284 break the molten solid material extending around the perimeter of the openings. The breaking of the molten solid material increases the softness of the web 240. The roller 284 has an outer smooth surface and is preferably constructed of a soft material such as rubber, polyamide, or other polymeric material. Referring now to Figure 5, the outer surface 281 of the roller 282 comprises a plurality of slots 283. The slots 283 extend around the outer surface 281 in a direction parallel to the machine direction. The slots can also extend in other directions. The size, spacing, shape and number of grooves can be selected to provide the desired softness in the weft 240 as the grooves help break the molten solid material that extends around the perimeter of the openings. The roller 282 is preferably constructed of steel. The linear peripheral speed of the rollers 282 and 284 is preferably greater than the linear peripheral speed of the rollers 254 and 260 thereby tensioning the material between the two sets of rollers. By adjusting the speeds of the rollers, the material is tensioned so that it achieves a desired quantity. From the second grip space 280 the weft 240 is wound into the winding roll 290. Referring now to Figure 6, there is shown a schematic illustration of another process 300 for forming the weft pattern of the present invention. A material 340 is unwound from a supply roll 310 and travels in the direction indicated by the arrows associated therewith, ie, in the machine direction, as the supply roll 310 rotates in the direction indicated by the associated arrows with the same. Instead of being unrolled from a supply roll the material can be fed directly from a forming apparatus, for example, a carding apparatus, a carding and calendering apparatus, a spinning linking apparatus, a spinning and calendering apparatus , a meltblowing apparatus, a meltblown and calendered blowing apparatus, to the first gripping space 350. The screen 340 is fed through the first gripping space 350 of the drilling apparatus 352 formed by the rollers 354 and 360. The roller 360 has an external smooth surface 362. The roller 360 is preferably constructed of steel. The roller 360 can be constructed of other materials, for example, rubber. Roller 354 includes a plurality of projections 358 extending around its outer surface 356. Roller 354 is preferably constructed of steel. The rollers 354 and 360 preferably rotate at the same speed. Although at least one of the rollers 354 and 360 is heated, preferably both rollers 354 and 360 are heated. Preferably, the roller 354 is heated to have a higher temperature than the roller 360. As the screen 340 passes through the first gripping space 350 it is perforated. As the weft is perforated, the weft is heated above its melting point in such a way that when a portion of the perimeter of the openings is melted. After the frame 340 has been perforated by the apparatus 352, the frame 340 is then cooled to immobilize the frame after leaving the apparatus 352. In Figure 6, the frame 340 is shown to be cooled by blowing cold air over the frame 340 from the fan 370. Of course, other known techniques for cooling the screen 340 can be used. The cooling of the screen also solidifies the molten material that extends around the perimeter of the openings. After cooling, the apertured web 340 is fed through the second grip space 380 formed by the rollers 382 and 384. The rollers 382 and 384 preferably rotate at the same speed. The rollers 382 and 384 break the molten solid material that extends around the perimeter of the openings. The breaking of the molten solid material increases the softness of the weft 340. The roll 384 has an outer smooth surface and is preferably constructed of a soft material such as rubber, polyamide, or other polymeric material. The outer surface of the roller 382 comprises a plurality of grooves. The roller 382 is the same as the roller 282 shown in Figure 5. The linear peripheral speed of the rollers 382 and 384 is preferably greater than the linear peripheral speed of the rollers 354 and 360 thereby tensioning the material between the two sets of rollers. By adjusting the speeds of the rollers, the material is tensioned so that it achieves a desired amount. From the second gripping space 380 the screen 340 is fed to the third gripping space 390 formed by the rollers 392 and 394. The rollers 392 and 394 preferably rotate at the same speed. The rollers 392 and 394 further break the molten solid material extending around the perimeter of the openings. The breaking or breaking of the molten solid material increases the softness of the weft 340. The roll 394 has a smooth outer surface and is preferably constructed of a soft material such as rubber, polyamide, or other polymeric material. Referring now to Figure 7, the outer surface 391 of the roller 392 comprises a plurality of grooves 393. The grooves 393 extend around the outer surface 391 in a different direction than the direction in which the grooves extend in the roller 382. Preferably , the slots 393 extend in a direction perpendicular to the direction in which the slots extend in the roller 382. The slots 393 are shown in Figure 7 to be extending in a direction perpendicular to the machine direction. The slots can also extend in other directions. The size, spacing, shape and number of grooves can be selected to provide the desired softness in the weft 340 as the grooves help to break the molten solid material that extends around the perimeter of the openings. The roller 382 is preferably constructed of steel. From the third grip space 390 the weft 340 is wound into the winding roll 398. Referring now to Figure 8, there is shown a schematic illustration of another process 400 for forming the weft pattern of the present invention. The process 400 is essentially identical to the process illustrated in Figure 6, except for the formation of the second and third gripping spaces 480 and 490. Unlike the process 300 illustrated in Figure 6, the process 400 uses the same smooth roller 484 to form the gripping spaces 480 and 490. This simply eliminates the need for two smooth rollers. The roller 482 is identical to the roller 282 illustrated in Figure 5 and the roller 492 is identical to the roller 392 illustrated in Figure 7. Instead of feeding an individual screen through the processes illustrated above, multiple frames can be fed simultaneously through the processes. The frames can be identical to one another or different from each other. For example, the frames may have different hydrophilic capacities in such a way that one is more hydrophilic than the other. The frames may have different dimensions such that one frame is wider than the other or thicker than the other. The various combinations and number of plies that can be punched and smoothed according to the present invention can be selected by the manufacturer to provide the desired results.

The diaper 20 may further comprise elastic leg cuffs (not shown) that provide improved containment of liquids and other exudates from the body. Each elasticized leg fold may comprise several different modalities to reduce leakage of body exudates in the leg regions. (The leg fold may be and is sometimes referred to as leg bands, side flaps, barrier folds, or elastic folds.) U.S. Patent No. 3,860,003 describes a disposable diaper 20 that provides a collapsible leg opening. having a lateral flap and one or more elastic members to provide an elasticized leg fold (packing fold). The commonly assigned 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 20 having "upright" elasticated fins (barrier folds). ) to improve the containment of leg regions. The commonly assigned U.S. Patent No. 4,695,278 entitled "Absorbent Article Having Double Folds" issued to Lawson on September 22, 1987, discloses a disposable diaper 20 having double folds including a gusset fold and a barrier fold. The diaper 20 preferably further comprises an elastic waist feature (not shown) that provides for improved fit and containment. The elastic waist feature is that portion or area of the diaper 20 that is intended to expand and contract elastically to dynamically adjust to the wearer's waist. The elastic waist feature extends at least longitudinally outwardly 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. Disposable diapers are generally constructed to having two characteristics of elastic waist, one placed in the first waist region 27 and one placed in the second waist region 29, although diapers can be constructed with a simple elastic waist feature. Further, although the elastic waist feature or any of its constituent elements may comprise a separate element secured to the diaper 20, the elastic waist feature is preferably constructed as an extension of other diaper elements 20 such as the back sheet 26 or the sheet upper 24, preferably both the backsheet 26 and the top sheet 24. The elasticized waistband can be constructed in a number of different configurations including those described in U.S. Patent No. 4,515,595 issued to Kievit and others on 7 May 1985 and the aforementioned U.S. patent application Serial No. 07 / 715,152; each of these references being incorporated herein by reference. The diaper 20 may also comprise a fastening system 36 that forms a side closure that holds the first waist region 27 and the second waist region 29 in an overlapping configuration so that lateral stresses are maintained around the circumference of the diaper 20 to maintain the diaper 20 on the wearer. Illustrative fastening systems are disclosed in the patent of the United States No. 4,846,815 entitled "Disposable diaper having an improved fastener device" issued Scripps on July 11, 1989; U.S. Patent No. 4,894,060 entitled "Disposable diaper with improved hook fastener portion" issued to Nestegard on January 16, 1990; the commonly assigned U.S. Patent No. 4,946,527 entitled "Pressure sensitive adhesive fastener and method for making same" issued to Battrell on August 7, 1990; the commonly assigned U.S. Patent No. 3,848,594 entitled "Disposable diaper tape fastener system" issued to Buell on November 19, 1974; the commonly assigned U.S. Patent No. B1 4,662,875 entitled "Absorbing Article" issued by Hirotsu et al. on May 5, 1987; and the above-referenced U.S. patent application Serial No. 07 / 715,152; each of which is incorporated herein by reference. The diaper 20 is preferably applied to a wearer by placing one of the waist regions, preferably the second waist region 29, below the user's back and pulling the rest of the diaper 20 between the user's legs in such a way that the other region of waist, preferably the first waist region 27, is placed across the front of the user. The tape tabs 36 of the fastener system are then released from the release portion. The person placing the diaper then wraps the elasticized side panel around the wearer, while still holding the tongue portion. The fastening system is secured to the outer surface of the diaper to make two lateral closures. Although the particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. Therefore, attempts are made to protect all these changes and modifications within the scope of this invention in the appended claims.

Claims (9)

1. A method for forming a screen with openings, said method comprising the steps of: a) feeding a screen in a machine direction through a first grip space formed by a pair of rolls having one of said rolls a smooth outer surface and the other roller having an outer surface with a plurality of projections extending from the outer surface, at least one of the rolls being heated, such that the screen is perforated with a plurality of openings having a molten perimeter; b) cooling the web to solidify the molten perimeter of said openings; and c) feeding the web through a second grip space formed by a pair of rollers to break the solidified molten perimeter of said apertures, one of said rollers of the second grip space having an outer surface with a plurality of slots. The method according to claim 1, comprising the additional step of: d) feeding the web through a third gripping space formed by a pair of rollers to break the solidified molten perimeter of said openings, one of said rollers of the third grip space having an outer surface with a plurality of grooves. The method according to claim 2 wherein the plurality of grooves in the outer surface of said roller forming the second gripping space extend in a first direction and said plurality of grooves in the outer surface of the roller forming the third Grip space extend in a different direction from the first direction. 4. The method according to claim 3, wherein said first address is parallel to the machine direction. 5. The method according to any of the preceding claims, wherein the frame comprises a nonwoven web. 6. The method according to claim 1, wherein a second web is simultaneously fed through the first and second gripping spaces. 7. The method according to any of the preceding claims, wherein the frame is cooled by blowing cold air onto the frame. The method according to any of the preceding claims, wherein one of the rollers forming the second gripping space has a smooth outer surface. The method according to any of the preceding claims, wherein one of the rollers forming the third gripping space has a smooth outer surface.