MXPA99007745A

MXPA99007745A - Tear resistant porous extensible web

Info

Publication number: MXPA99007745A
Application number: MXPA/A/1999/007745A
Authority: MX
Inventors: Ann Mansfield Michele; Joseph Curro John; Christophe George
Original assignee: The Procter & Gamble Company
Priority date: 1997-02-21
Filing date: 1999-08-20
Publication date: 2000-02-02

Abstract

The present invention pertains to a porous, macroscopically-expanded three-dimensional, elastomeric web suitable for use in elasticized portions of disposable absorbent articles such as bandages, diapers and pull-up diaper training pants. In a preferred embodiment the web has a continuous first surface and a discontinuous second surface remote from first surface. An elastomeric web of the present invention preferably comprises a formed film having at least two polymeric layers, with at least one of the layers being an elastomer and at least one of the other layers being a substantially less elastomeric skin layer. In a preferred embodiment the elastomeric web exhibits a multiplicity of primary apertures in the first surface of the web, the primary apertures being defined in the plane of the first surface by a continuous network of interconnecting members. Each interconnecting member exhibits an upwardly concave-shaped cross section along its length. The interconnecting members terminate substantially concurrently with one another to form a secondary aperture in the plane of the second surface of the web. Also disclosed is a method of producing the elastomeric web of the present invention comprising providing a multilayer elastomeric film, supporting the film on a forming structure, and applying a fluid pressure differential across the thickness of the multilayer film. The fluid pressure differential is sufficiently great to cause the multilayer film to conform to the supporting structure and rupture in at least portions of the formed film.

Description

EXTENSIBLE POROSA FRAME RESISTANT TO DISPOSAL FIELD OF THE INVENTION The present invention relates to porous polymeric extensible webs. In particular, the present invention relates to polymeric frames with macroscopically expanded three-dimensional openings.

BACKGROUND OF THE INVENTION - < o It has long been known in the field of disposable absorbent articles that it is desirable to construct absorption devices such as disposable diapers, sanitary napkins, incontinence pads, bandages, wound dressings, and the like, with elastic elements to improve the size range, the The ease of movement, and the sustained adjustment, has also been known to be preferable, especially in products intended to be used in conditions of heat and humidity, to provide adequate porosity to all areas of the article where undue occlusion of the Skin may cause sensitized skin or heat rash. Due to the nature of many absorbent articles there is a high potential for skin irritation due to entrapment of moisture and other body exudates between the elasticized portion and other exudates of the body between the elasticized portion of the article and the wearer's skin. The elasticized portions of the disposable articles are particularly prone to cause skin irritations since they tend to be more comfortable to the body, and therefore, more likely to occlude the areas of the skin, to often for long periods of time. Various methods for imparting elasticity to polymeric films are known and various methods are known in the art for imparting porosity to polymeric films, however there remains a need for a polymeric film or weft that provides both adequate elasticity and porosity, as be adapted for durable garments of prolonged use, particularly disposable garments. Disposable diapers and other absorbent articles fitted with elastic leg cuffs or elasticised waistbands for a more comfortable fit as well as to provide better control of leakage or leakage are known in the art. Often, the elasticity is achieved with a thermal treatment of the polymeric materials that results in desirable shrinkage or removal of a part of the diaper. One of these methods of treatment is disclosed in U.S. Patent No. 4,681, 580 issued to Reising et al. On July 21, 1987, and hereby incorporated by reference herein. An improved method for sequentially stretching a laminated "zero tension" stretch fabric to impart elasticity to it is disclosed in U.S. Patent No. 5,143,679 issued to Weber et al. On September 1, 1992, and incorporated by the present here by reference. The Weber '679 patent teaches the use of a stretch laminate formed of at least two layers, one of which is stretchable and elastomeric, while the second layer is stretchable but not necessarily elastomeric. The layers are, either, continually secured intermittently or substantially to one another along at least a portion of their coextensive surfaces while they are in a substantially unstressed condition ("zero stress"). U.S. Patent No. Weber '679 further discloses an improved method and apparatus for sequentially stretching the portions of the "zero tension" stretch laminate of the weft during the incremental stretch process to impart elasticity in the direction of the stretch. without breaking the film web in the process. Further improvements are taught in U.S. Patent No. 5,156,793 issued to Buell et al. On October 20, 1992 and 5,167,897 issued to Weber and others on December 1, 1992, both of which are hereby incorporated by reference. here. Elasticized polymeric webs can also be produced from elastomeric materials known in the art, and can be laminated from polymeric materials such as disclosed in U.S. Patent No. 5,501, 679 issued to Krueger et al. on March 26, 1996. Laminates of this type are generally prepared by or extrusion of the materials elastomeric and inelastic cover layers followed by rolling stretch past the elastic limit of the cover layers and then the laminate is allowed to recover. Films or elastomeric webs such as those described above, may be used in portions of garments that adhere to the body, such as waistband portions and leg cuffs, but are generally not porous enough to avoid undesirable skin irritations. when they are used for extended periods of time. Various means are known in the art for making the more porous elastified planar polymeric films, such as punching, slotting and hot-bolt melting aperture. However, when any of the above techniques are applied to thermoplastic elastomeric films, the increase in porosity is accompanied by a decrease in the degree of reliable elastic performance. For example, in the case of circular openings in a flat film, it is well known that for an applied voltage, a resulting local voltage S ^ is created orthogonal to the applied voltage around the openings. This local voltage S2 is greater than SL approaching a magnitude of up to three times the applied voltage. For non-round openings, the concentration of tension may be even greater. As a result, the openings become sources of tear initiation sites on their edges, because the edges of the material form the edges of the openings in the plane of the applied tension. For common thermoplastic elastic films, these openings facilitate the onset of tearing which can propagate over time, leading to catastrophic failure of the film. When used in elasticized portions of the disposable absorbent articles, this failure results in the loss of important elastic characteristics, including loss of comfort, fit and use of the absorbent article. Prior art weft structures that provide adequate porosity to be preferable for use as the user interface in the disposable absorbent articles have found two basic varieties, i.e. structures inherently permeable to fluid, ta! such as fibrous nonwoven materials, and fluid impervious materials such as polymeric webs that have been provided with a degree of permeability to the fluid through the perforation to allow the flow of fluid and moisture therethrough. Neither the variety is characteristically elastic, and as a result both are generally used in the regions of an absorbent article that requires fluid permeability but not extensibility, such as the layer that is in contact with the body of a catamenial pad. The commonly assigned U.S. Patent No. 3,929,135, issued to Thompson on December 30, 1975, and hereby incorporated by reference, suggests a porous polymeric web that is in contact with the body suitable for disposable articles. Thompson teaches a macroscopically expanded three-dimensional top sheet composed of liquid impervious polymer material. However, the polymeric material is formed to comprise tapered capillaries, the capillaries having a base opening in the plane of the topsheet, and a vertex opening in intimate contact with the absorbent pad used in the disposable absorbent web. The polymeric material taught by Thompson is not generally an elastomer, however, and Thompson depends on the non-elastic properties of the single-layer film molded with heat to produce the desired three-dimensional structure. Yet another material that has been used as a surface that is in contact with the body in the context of the disposable absorbent article is disclosed in commonly assigned United States Patent No. 4., 342,314 issued to Radel et al. On August 3, 1982, and incorporated herein by reference. The Radel patent discloses an improved three-dimensional, macroscopically expanded plastic web that contains a regulated continuum of capillary networks originating in and extending from a weft surface and ending in the form of openings in the opposite surface thereof. In a preferred embodiment, the capillary networks are of decreasing size in the direction of liquid transport. Macroscopically expanded three-dimensional plastic webs of the type generally described in the aforementioned commonly assigned Thompson and Radel et al patents have met with success in allowing adequate liquid permeability due to the porosity provided by the openings. However, because of the limitations of the material these webs do not generally possess the elasticity required to allow the resulting web to have significant elastomeric characteristics. This defect substantially limits the use of these wefts in the elasticized portions of an absorbent article. Accordingly, it would be desirable to provide an apertured elastomeric weave designed to dissociate the effects of a tension applied to the weft from the edges of the openings and consequently retard or prevent the onset of tear initiation. More particularly in a particularly preferred embodiment it would be desirable to provide a three-dimensional, macroscopically expanded elastomeric aperture, which is capable of substantially recovering its three-dimensional shape after being subjected to an applied voltage of up to about 400% or more.

BRIEF DESCRIPTION OF THE INVENTION In a preferred embodiment, the present invention pertains to an elastomeric, three-dimensional, macroscopically expanded fabric for use in elasticized portions of disposable absorbent articles such as bands, diapers that climb up the legs, training pants. In a preferred embodiment, the web has a first continuous surface and a second discontinuous surface remote from the first surface. An elastomeric web of the present invention preferably comprises a formed film having at least two polymeric layers with at least one layer which is an elastomer and at least one layer which is a substantially less elastomeric covering layer. In a preferred embodiment the elastomeric web exhibits a multiplicity of primary openings in the first surface of the web, the primary openings being defined in the plane of the first surface by a network of continuous interconnecting members, each interconnecting member exhibiting a cross section with concave shape upwards along its length. In a preferred embodiment, each interconnecting member exhibits a generally U-shaped cross section along a portion of its length, the cross section comprising a base portion generally in the plane of the first surface of the screen and portions of the screen. side wall joined to each edge of the base portion and interconnected with other side wall portions. The interconnected side wall portions generally extend in the direction of the second surface of the screen, and are interconnected to one another between the first and second surface of the screen. The interconnected side wall portions terminate substantially concurrently with one another to form a secondary opening in the plane of the second surface of the frame. Also disclosed is a method for producing an elastomeric web of the present invention comprising providing a multilayer elastomeric film, holding the film on a forming structure, and applying a fluid pressure differential across the film thickness and multiple layers. The fluid pressure differential is sufficiently large to cause the multilayer film to shape the support structure and break at least the portions of the formed film. When used as an extendable, porous member in an absorbent article, the elastomeric layer of the present invention allows the interconnecting members to stretch in the plane of the first surface. The three-dimensional nature of the weft places the second openings in a plane of the second surface remote from the plane of the first surface, initially removing the web stresses from the tear initiation sites on the edges of the second openings. The initial tension of the frame results in the base of the interconnection members that experience the tension in the first surface. As the tension of the weft increases, the side wall portions of the interconnecting members intermediate the first and the second surfaces experience tension as they approach the plane of the first surface. Finally, on the adequate tension of the frame, the plane of the second surface approaches the plane of the first surface and the edges of the secondary openings will experience the tension of the frame as well. Therefore, the three-dimensional nature of the web allows the tension on the interconnection members in the plane of the first surface to be dissociated from the stress in the secondary openings in the secondary surface, and therefore decoupled from the induced potential voltage. by the effort in the sites of tear initiation. This dissociation, or decoupling, of the stress induced by the stress of the weft from stress induced by the stress in the secondary openings significantly increases the reliability of the weft allowing the repeated and sustained web tensions of up to about 400 % or greater without failure of the weft due to the initiation of tearing in the openings.

BRIEF DESCRIPTION OF THE DRAWINGS Although the description concludes with the claims pointing out in a particular manner, and claiming differently the subject matter of the present invention, it is believed that the present invention will be better understood from the following description taken in combination with the accompanying drawings, in which like reference numbers identify identical elements where: Figure 1 is a perspective illustration, partially segmented, enlarged, of a prior art polymeric web of the type generally disclosed in the commonly assigned U.S. Patent No. 4,342,314; Figure 2 is a perspective illustration, partially segmented, enlarged, of a preferred elastomeric web of the present invention having two layers of polymer film, at least one of which is elastomeric; Figure 3 is a more enlarged partial view of a web of the type generally shown in Figure 2, but illustrating in greater detail the construction of the weft of an alternate elastomeric web of the present invention; Figure 4 is an enlarged cross-sectional view of a preferred multilayer film of an elastomeric web of the present invention having an elastomeric layer interposed between the cover layers; Figure 5 is a plan view of the aperture shapes projected in the plane of the first surface of an alternate elastomeric web of the present invention; Figure 6 is an enlarged cross-sectional view of an interconnection member taken along section line 6-6 of Figure 5; Figure 7 is another enlarged cross-sectional view of an interconnection member taken along section line 7-7 of Figure 5; Figures 8a to 8c are schematic representations of a cross-section of an aperture of an elastomeric weft of the present invention in various tension states; Figure 9 is an amplified optimal photomicrograph showing the first surface of an elastomeric web of the present invention having an ordered pattern of about 1 square millimeter of aperture; Figure 10 is a perspective illustration of the scanning electron microscope photomicrograph of the second surface of the elastomeric web shown in Figure 9 in an unstretched state; Figure 11 is a perspective illustration of the amplified scanning electron microscope photomicrograph of the second surface of the elastomeric web shown in Figure 9 tensioned at approximately 100% tension; Figure 12 is a perspective illustration of the amplified scanning electron microscope photomicrograph of an elastomeric aperture of the present invention showing the roughness formed after extension and recovery; Figure 13 is a partially segmented perspective illustration of a disposable garment comprising the elastomeric fabric of the present invention; Figure 14 is a simplified, partially segmented illustration of a preferred embodiment of the side panels for a disposable garment; Figure 15 is a partially exploded, simplified perspective illustration of a laminated structure generally useful for forming the weft structure illustrated in Figure 2; Figure 16 is a perspective view of a tubular member formed by winding a flat laminated structure of the type generally illustrated in Figure 15 to the desired radius of curvature and joining the free ends thereof to each other; Figure 17 is a simplified schematic illustration of a preferred method and apparatus for embossing and perforating an elastomeric film generally in accordance with the present invention; Figure 18 is a partially segmented, enlarged perspective illustration of an alternate elastomeric web of the present invention; and Figure 19 is an enlarged cross-sectional illustration of the screen of Figure 18 taken along section line 19, -19.

DETAILED DESCRIPTION OF THE INVENTION Figure 1 is a perspective illustration, partially segmented, enlarged, of a macroscopically expanded, three-dimensional, fluid-permeable, polymer-permeable polymer frame that has been found highly suitable for use as a topsheet in disposable absorbent articles. , such as diapers and sanitary napkins. The prior art scheme is generally in accordance with the teachings of the commonly assigned U.S. Patent No. 4,342,314 issued to Radel et al. On August 3, 1982, which is incorporated by reference. The fluid-permeable web 40 exhibits a multiplicity of openings, for example, openings 41, which are formed by a multiplicity of interconnected fiber-shaped elements, for example, the fiber-shaped elements 42,43,44, 45 and 46 connected one to the bulls on the first surface 50 of the frame. Each fiber-shaped element comprises a base portion, for example, the base portion 51, located in the plane 52 of the first surface 50. Each base portion has a side wall portion, for example, the wall portion lateral 53, attached to each edge of it. The side wall portions extend generally in the extension of the second surface 55 of the weft. The intersecting side wall portions of the fiber-shaped elements are interconnected to one another intermediate to the first and second surface of the frame, and terminate substantially concurrently with one another in the plane 56 of the second surface 55. In one preferred embodiment, the base portion 51 includes a microscopic pattern of surface aberrations 58 generally in accordance with the teachings of U.S. Patent No. 4,463,045 issued to Ahr et al. on July 31, 1984, the disclosure of which is incorporated here by reference. The pattern of microscopic surface aberrations 58 provides a substantially non-glossy visible surface when the screen is struck by incident light rays. In an alternate embodiment, the above frame may include multiplicity of much smaller capillary networks (not shown) on the first surface of the frame, as taught by U.S. Patent No. 4,637,819 of Ouellette and others issued on January 20. of 1987 and incorporated herein by reference. It is believed that the additional achieved porosity provided by the minor capillary networks of fluid handling may allow the weft of the present invention to function more efficiently when used as a porous extensible part of a disposable absorbent article. As used herein, the term "interconnecting members" refers to some or all of the elements of the parts of the elastomeric web of which serve to define the primary openings by a continuous network. Representative cross-connection members include, but are not limited to, fiber elements of the aforementioned U.S. Patent No. 4,342,314 Radel et al. And commonly assigned U.S. Patent No. 5,514,105 to Goodman Jr., and others, issued May 7, 1996 and incorporated herein by reference. As can be seen from the following description and drawings, the interconnecting elements are inherently continuous with contiguous interconnecting elements combining in mutually contiguous transition parts with each other. The individual interconnecting members can be better described generally, with reference to Figure 1, as those parts of the elastomeric web disposed between any two adjacent main openings, which originate in the first surface 50 and extend toward the second surface 55. On the first surface of the frame the interconnection members collectively form a continuous network or pattern, the network of interconnecting members continues to define the primary openings, and on the second surface of the frame the lateral interconnecting walls of the interconnection members collectively form a pattern of discontinuous secondary openings. As used herein, the term "continuous", when used to describe the first surface of the elastomeric web, refers to an uninterrupted character of the first surface, generally in the plane of the first surface. In this way, any point on the first surface can be reached from any and almost another point on the first surface without substantially leaving the first surface in the plane of the first surface. Also, as used herein, the term "discontinuous" when used to describe the second surface of the elastomeric web, refers to the interrupted character of the second surface generally in the plane of the second surface. In this way, any point on the second surface can not be reached from any other point on the second surface without substantially leaving the second surface in the plane of the second surface. In general, as used herein, the term "macroscopic" is used to refer to features or structural elements that are readily visible to a normal human eye when at the perpendicular distance between the eye of the observer and the plane of the frame It is approximately 12 inches. Conversely, the term "microscopic" is used to refer to features or structural elements that are not easily visible by a normal human eye when the perpendicular distance between the eye of the observer and the plane of the frame is approximately 12 inches. As used herein, the term "macroscopically expanded," when used to describe tapes or webs and films, refers to the elastomeric webs, tapes and films which have been caused to conform to the surface of an three-dimensional structure of formation in such a way that both surfaces thereof exhibit the three-dimensional pattern of the forming structure.These macroscopically expanded webs, tapes and films are typically made to conform to the surface of the forming structures by embossing (i.e. , when the forming structure exhibits a pattern composed mainly of male projections, by embossing in low relief (i.e., when the forming structure exhibits a pattern composed mainly of female capillary networks), or by extruding a molten resinous material over the surface of a training structure of any kind. In contrast, the term "flat" when used here to describe plastic wefts, tapes, and films refers to the overall overall condition of the weft, tape, or film when viewed with the naked eye on a macroscopic scale. For example, an extruded film without apertures or an apertured extruded film that does not exhibit sufficient macroscopic deformation outside the plane of the film would generally be described as planar. In this way, for an open planar web, the edge of the material in the openings is substantially in the plane of the web, causing the web stresses applied in the plane of the web that is directly coupled to the web start sites. tearing in the openings. When expanded macroscopically, the multilayer film of the elastomeric web of the present invention is formed into three-dimensional interconnecting members that can be described as channel-like. Its two-dimensional cross section can also be described as "U-shaped" as in the aforementioned Radel and others patent, or more generally concave upwardly as disclosed in the aforementioned Goodman patent, Jr. and others. "Concave-up" shaped, as used herein, describes the orientation of the channel-shaped configuration relative to the surfaces of the elastomeric web, with the base generally on the first surface, and with the legs or extensions of the channel extending from the base in the direction of the second surface, and with the opening of the channel being substantially on the second surface. In general, as described below with reference to Figure 5, for a plane extending through the frame orthogonal to the plane of the first surface and intersecting any of two adjacent primary openings, the resulting cross section of an interconnect member disposed therebetween will exhibit a generally upwardly concave shape which may be substantially U-shaped. A disadvantage associated with the macroscopically expanded, three-dimensional, fluid-permeable salt frames of the prior art is that despite its breathability and handling characteristics, Higher fluid, these are not elastic enough to be used in the high stretch portions of the disposable absorbent articles such as waistbands and leg cuffs. Flat elastified polymeric webs without apertures that exhibit adequate expandability for use in disposable absorbent articles have disadvantages as well. In particular, the flat elastified polymeric webs, without apertures, do not have the proper porosity to be used in the parts that are in contact with the body of an absorbent article. Various means are known in the art to make the elastified polymeric plies flat, without more porous openings such as punching, die-cutting, and hot-melt opening. However, when any of the above techniques are applied to thermoplastic elastomeric films, the increase in porosity is typically accompanied by the decrease in the degree of safe elastic performance. Once drilled by conventional methods. The edges of the openings become the source of tear start sites as the forces are applied to the frame since they are located within the plane of the applied tension. For common thermoplastic elastic films the tension of the weft will start tearing at the openings which propagates over time, resulting in the catastrophic failure of the film. If the shapes of the openings are not rounded, for example, square, triangular or other polygon, the potential of tearing initiation is increased due to the concentrations of the tensions at the angular intersections of the sides.

The Applicant has discovered if a flat elastomeric web can be formed in a macroscopically expanded three-dimensional fluid permeable web, generally in accordance with the teachings of the aforementioned Radel 4,342,314 patent and others, the resulting three-dimensional elastomeric web exhibits the advantages of high porosity and high elasticity, as well as superior reliability and resistance. Applicants have achieved this in the present invention by using a multilayer polymeric web comprising an elastomeric layer in combination with at least one cover layer, and the formation of the multilayer web in a three-dimensional, macroscopically expanded configuration. As used herein, the term "elastomer" is intended to include any material that is capable of being formed into a film layer and which exhibits elastomeric properties. "Elastomeric" means that the material will substantially assume its original shape after being stretched and, preferably will sustain only little permanent deformation followed by deformation and relaxation. Preferably, the elastomeric layer itself is capable of being subjected to 50% to 1200% elongation at room temperature when it is in a flat, non-apertured condition. The elastomer may be any of the pure elastomers or a mixture with an elastomeric phase or elastomeric content that will still exhibit substantial elastomeric properties at ambient temperatures, including human body temperatures. As used herein, "cover layer" refers to a layer of any semicrystalline or amorphous polymer that is less elastic than the elastomer layer. The cover layer of the present invention is preferably thinner and substantially less elastic than the elastomeric layer, and may in the limiting case be generally non-elastic. There can be more than one cover layer used in combination with the elastomeric layer of the present invention and this or these will generally modify the elastic properties of the elastomer. If more than one cover layer is used, the cover layers may have the same or different material characteristics. Without being bound by the theory it is believed that the cover layers serve to maintain the three-dimensional structure of the formed elastomeric web of the present invention. Figure 2 is a perspective illustration, partially segmented, enlarged, of a three-dimensional, macroscopically expanded, elastomeric weft pattern of the present invention, generally indicated as 80. The geometrical configuration of the fluid-permeable elastomeric weave 80 is generally similar to that of the prior art frame 40. illustrated in Figure 1, and is generally in accordance with the teachings of the prior of U.S. Patent No. 4,342,314 Radel et al. Other suitable formed film configurations are described in U.S. Patent No. 3,929,135 issued to Thomspon on December 30, 1975; U.S. Patent No. 4,324,246 issued to Mullan et al. on April 13, 1982; and in U.S. Patent No. 5,005,394 issued to Barid on April 9, 1991. Disclosures of each of these patents are hereby referenced. A preferred embodiment of an elastomeric web 80 of the present invention exhibits a multiplicity of primary openings, for example, primary openings 71, which are formed in the plane 102 of the first surface 90 by a continuous interconnection network, for example, members 91,92,93,94,95 interconnected to each other. The shape of the primary openings 71 as they project onto the plane of the first surface 90 are preferably in the form of polygons, for example, squares, hexagons, in an ordered or random pattern. In a preferred embodiment each interconnection member comprises a base portion, for example, the base portion 81, located in the plane 102 and each base portion has a side wall portion, for example, the side wall portions 83, attached to each edge thereof. The side wall portions 83 extend generally in the direction of the second surface 85 of the weft and intersect with the side walls of the adjacent interconnecting members. The intersecting sidewall portions are interconnected to one another intermediate to the first and second weft surfaces, and terminate substantially concurrently with one another to form a secondary opening, eg, secondary openings 72 in plane 106 of the second surface 85. Figure 3 is a more enlarged partial view of the type generally similar to the screen 80 of Figure 2, but illustrating an alternate construction of the screen according to the present invention. The multilayer polymeric formed film 120 of the weft 80 is preferably composed of at least one elastomeric layer 101, and at least one covering layer 103. Although Figure 3 shows a two layer embodiment with the covering layer 103 closer to the first surface 90, it is believed that the order of the formed layers 120 is not limiting. Although it is currently preferred that, as shown in Figure 3, the polymer layers end substantially concurrently in the plane of the second surface, it is not currently believed that it is essential that this be so, ie, one or more layers can extend more towards the second surface than the others. A particularly preferred multilayer polymeric film 120 of the weft 80 is illustrated in the cross section in Figure 4 which shows an elastomeric layer 101 interposed between two sheath layers 103. The elastomeric layer 101 preferably comprises a thermoplastic elastomer composed of a matrix amorphous substantially continuous with vitreous or crystalline domains scattered throughout, the domains acting as effective physical bonds and consequently allowing the material to exhibit an elastic memory when subjected to an applied stress and subsequently released. Preferred elastomeric materials include block copolymers and mixtures thereof, such as styrene-butadiene-styrene copolymers or other common styrenic block copolymers as are generally available from the Shell Company under the tradename "DRATON". Similarly, polyolefin materials such as polyethylene and polypropylene generally of densities below about 0.9 grams per cubic centimeter may also exhibit the necessary thermoplastic character and the resulting elastic behavior. The cover layers preferably comprise any thermoplastic polymer especially polyolefin polymers such as polyethylene or polypropylene generally of density greater than about 0.9 g / cc, which are capable of processing the thermoplastic into thin films. The cover layers must have sufficient adhesive to the elastomeric layer such that they will not completely delaminate either before or after the stretch of the weft. A preferred method for producing a multilayer polymer film 120 is co-extrusion. Figure 5 is a plan view of the alternate configurations of the primary aperture projected in the plane of the first surface of an alternate elastomeric web of the present invention. Although a preferred pattern of repetitive uniform shapes, the shape of the primary openings, e.g., openings 71, may be generally circular, polygonal or mixed and may be arranged in an ordered pattern or in a random pattern. Although not shown, it is understood that the projected shape may also be elliptical in the shape of a drop, or any other form, that is, it is believed that the present invention is independent of the shape of the opening. The interconnection elements are inherently continuous with contiguous interconnecting elements combined with each other in mutually immediate transition zones or parts., for example, transition portions 87, shown in Figure 5. In general, the transition portions are defined by the largest circle that can be inscribed tangent to any of three adjacent openings. It is understood that for certain patterns of openings, the written circle of the transition portions may be tangent to more than three adjacent openings. For illustrative purposes the interconnection members can be considered as starting or ending substantially at the centers of the transition portions, such as the interconnecting members 97 and 98. Also, the side walls of the interconnecting members can be described as interconnecting the side walls of the adjacent interconnecting members in the areas corresponding to the tangency points where the inscribed circle of the transition portion is tangent to an immediate opening. Exclusive of the transition zones, the cross sections traverse the center line between the start and the end of the interconnecting members are preferably generally U-shaped in shape. However, the cross section does not need to be uniform along the total length of the interconnect member and for certain opening configurations it will not be uniform over most of its length. For example, as can be understood from the sectional illustrations of Figure 5, for the interconnect member 96, the width dimension 86, of the base portion 81 can vary substantially from the length of the interconnect member. In particular, in the transition zones or portions 87, the interconnection members combined in the contiguous interconnecting members and the transverse cross sections in the transition zones or portions may exhibit substantially non-uniform forms of U or non-dissociable form of U. Without wishing to be bound by the theory, it is believed that the frame of the present invention is safer (i.e., resistant to catastrophic failure), when it is subjected to tension induced by the stress due to the mechanism illustrated schematically in the cross section in Figures 8a to 8c and graphically in photomicrographs 9 to 11. Figure 8a shows a primary aperture 71 in the plane 102 of the first surface 90 and a secondary aperture 72 in the plane 106 of the second surface 82, far from the plane 106 of the plane of the first surface 90 of the frame 80 in a non-stressed condition. When the weft 80 is stretched in the direction generally shown by the arrows in Figure 8B the first surface 90 is subjected to stress and the primary opening 71 is also subjected to stress in a deformed configuration. However, the perimeter of the primary opening 71 is formed by the interconnecting members in a first continuous surface, therefore, the opening 71 does not have "edges" for the tear initiation sites that compromise the elastic reliability of the weft. . The edges of the secondary opening 72, with tear initiation sites being possible, do not experience appreciable stress-induced stresses until the web is stressed to the point where the plane 110 is no longer away from the plane 106 of the first surface 90, as shown in Figure 8C. at the point where the planes 102 and 106 are no longer remote, the screen 80 begins to behave essentially as a flat screen with openings. It is instructive to consider the ratio of the total depth of the "D" frame in Figure 8A, to the thickness of the "T" film in Figure 8A of an undrawn elastomeric web. This ratio of D / T can be called the stretch ratio, since this pertains to the amount of stretching of the film outside the plane of the first surface due to the forming process of the present invention. The applicant believes that in general, an increase in the stretch ratio serves to increase the tear strength by placing the first surface farthest from the first surface. Without wishing to be bound by theory, it is believed that when the web is stressed or stretched, the elastomeric layer 101 of the present invention allows the base 81 of the interconnecting members forming a continuous web on the first continuous surface to stretch. . The cover layer 103 helps to maintain the three-dimensional nature of the weft, despite the applied tension, allowing the stress on the first surface to continue 90 and the resulting deformation of the primary openings 71 to be at least partially dissociated from the second surface discontinuous, thus minimizing the stress to the secondary openings 72. Therefore, the tension induced by the stress in the first continuous surface of the web is substantially decoupled from the potential voltage induced by the stress at the tear initiation sites on the second discontinuous surface, at least until the secondary openings begin to enter the plane of the first surface. This substantial dissociation or decoupling of stress induced by the stress-induced strain of the tension in the secondary openings significantly increases the reliability of the weft allowing repeated and sustained weft stresses of up to about 400% or more without failure of the frame due to the beginning of tearing in the openings. The photomicrographs of Figures 9 to 11 are believed to visually depict the mechanism described schematically in Figures 8A to 8C. Figure 9 is an optical photomicrograph showing the first surface and the primary openings and one embodiment of the present invention. In a non-extended configuration as it is formed, the first continuous surface of the pattern mode shown in Figure 9 generally forms a regular pattern of one square millimeter of primary openings spaced about one millimeter apart on all sides. Figures 10 and 11 are scanning electron microscope photomicrographs showing the second discontinuous surface of the pattern mode of Figure 9, shown at a slightly different scale. Figure 10 shows the second surface of an elastomeric web, generally a plane away from the first surface in an unstretched state. Figure 11 shows the second surface of a frame in a state of approximately 100% stress. As shown in Figure 11, the edges of the secondary openings remain remote from the plane of the second surface. Although some distortion of the secondary openings occurs, the edges remain in a substantially unstressed condition. Again, in this substantial decoupling of the stress induced by the stress-induced strain of the tension in the secondary openings which significantly increase the reliability or safety of the weft. The differential elastic behavior of flat multi-layer films or fibers having a relatively less elastic cover layer stretched beyond their elastic limit is known in the art, as described in the aforementioned Krueger et al. Patent, as well as in U.S. Patent No. 5,376,340 to Swenson et al., issued December 27, 1994 and 5,352,518 to Muramoto et al., issued October 4, 1994. As shown in the art, upon recovery after extending beyond the elastic limits of the cover layer, the cover layer can form a microscopic microtexture of peak and valley irregularities, due to the increased surface area resulting from the layer of. cover relative to the elastomeric layer. Also, when a plot of the present invention is subjected to effort for a first time, the cover layer of the portion subjected to stress may be stressed beyond its elastic limit. The elastomeric layer allows the weft to return substantially. The elastomeric layer allows the weft to return substantially to its macroscopically pre-tensioned three-dimensional configuration but the parts of the skin layer that were stressed beyond its elastic limit may not return to a pre-tensioned configuration due to the excess material created in the non-elastic stress . Upon recovery after extension, the cover layer forms a microscopic microtexture of peak and valley irregularities more generally described as transversely extending rugosities as shown in the photomicrograph of Figure 12. Roughness is formed on the interconnection members in substantially uniform patterns generally transverse to the direction of stretching, and generally radially disposed about the primary openings. Depending on the degree of stress on the web, the roughnesses may be limited to substantially the first continuous surface of the web, or more generally may extend substantially over the total surface of the interconnecting members. Without being bound by the theory, it is believed that the transversally extending roughnesses are beneficial to the elastomeric web for at least two reasons. First, the roughness imparts a softer overall texture or feel to the elastomeric web, second, the rugosities, which are radially disposed to the primary openings and extending to the secondary openings, can facilitate better fluid handling characteristics when used as a weft that is in contact with the body of a disposable absorbent article. A representative embodiment of an elastomeric fabric of the present invention used in a disposable absorbent article in the form of a diaper 400, is shown in Figure 13. As used herein, the term "diaper" refers to a garment. Generally used by babies and incontinent people that is used around a user's lower torso. However, it should be understood that the elastomeric web of the present invention is also applicable to other absorbent articles such as incontinence briefs, training pants, sanitary napkins and the like. The diaper 400 illustrated in Figure 13 is a simplified absorbent article that can represent a diaper before being placed on a wearer. However, it should be understood that the present invention is not limited to the particular type or configuration of diaper shown in Figure 13. A particularly preferred representative embodiment of a disposable absorbent article in the form of a diaper is taught in the United States patent. No. 5,151, 092 to Buell et al., Issued September 29, 1992, which is hereby incorporated by reference. Figure 13 is a perspective view of the diaper 400 in its non-contracted state (ie, with all the contraction induced by the removed elastic), with part of the structure being cut away to more clearly show the construction of the diaper 400. part of the diaper 400 that is in contact with the user faces the observer. The diaper 400 is shown in Figure 13 to preferably comprise a liquid-permeable upper sheet 404; a backsheet 402 impermeable to the liquid bonded to the topsheet 404, and an absorbent core 406 positioned between the topsheet 404 and the backsheet 402. Additional structural features such as elastic leg bending members and fastening means may also be included. to secure the diaper in place on a user. Although the topsheet 404, the backsheet 402 and the absorbent core 406 can be assembled in a variety of well-known configurations, a preferred diaper configuration is generally described in U.S. Patent No. 3,860,003 to Buell issued on 14 January 1975, the disclosure of which is incorporated by reference. Alternatively, preferred configurations for disposable diapers are also disclosed in U.S. Patent No. 4,808,178 to Aziz et al., Issued February 28, 1989; U.S. Patent No. 4,695,278 to Lawosn, issued September 22, 1987; U.S. Patent No. 4,816,025 to Foreman, issued March 28, 1989, the disclosures of each of these patents are hereby incorporated by reference. Figure 13 shows a representative embodiment of the diaper 400 in which the topsheet 404 and the backsheet 402 are coextensive and have length and width dimensions generally greater than those of the absorbent core 406. The topsheet 404 is attached to and superimposed on the sheet. rear sheet 402 thus forming the periphery of diaper 400, the periphery defining the outer perimeter or edges of diaper 400. The periphery comprises end edges 401 and longitudinal edges 403. The size of back sheet 402 is dictated by the Absorbent core size 406 and the exact design of the selected diaper. In a preferred embodiment, the backsheet 402 has a modified hourglass shape extending beyond the absorbent core 406 at a minimum distance of at least 1.3 cm to about 2.5 cm around the total periphery of the diaper. The topsheet 404 and the backsheet 402 are joined together in any suitable manner. As used herein, the term "attached" encompasses configurations by means of which the top sheet 404 joins directly to the back sheet 402 by attaching the top sheet 404 directly to the back sheet 402, and configurations by which the sheet upper 404 indirectly attaches to upper sheet 402, by attaching upper sheet 404 to intermediate members which in turn are affixed to back sheet 402. In a preferred embodiment, upper sheet 404 and back sheet 402 are fixed directly each other at the periphery of the diaper by joining means (not shown), such as an adhesive or any other joining means as is known in the art. For example, a continuous uniform adhesive layer, a patterned adhesive layer or an array of separate adhesive lines or dots may be used to secure the upper sheet 404 to the back sheet 402. The end edges 401 form a waist region , which in a preferred embodiment comprises a pair of elastomeric side panels 420, which extend laterally from the end edges of the diaper 400 in an extended configuration. In a preferred embodiment the elastomeric side panels 420 comprise the elastomeric web of the present invention. In an especially preferred embodiment when used as the elastomeric side panels, the weft of the present invention is further processed to form a composite laminate by joining it on, or preferably on both sides thereof, with fibrous nonwoven materials to form an elasticized member. , gentle, docile using methods known in the art, such as adhesive bonding. Fibrous nonwoven materials suitable for use in a composite laminate of the present invention include nonwoven webs formed from synthetic fibers (such as polypropylene), polyester or polyethylene), natural fibers (such as cotton, or rayon), or combinations of natural and synthetic fibers. Suitable non-woven materials can be formed by various processes such as carding, spun bonding, hydroentanglement and other processes familiar to those with knowledge or expertise in the non-woven material technique. A currently preferred fibrous nonwoven material is loaded polypropylene, commercially available from Fiberweb of Simpsonville, S.C. The fibrous nonwoven materials can be attached to the elastomeric web by any of several joining methods known in the art. Suitable bonding methods include adhesive bonding such as by a continuous uniform adhesive layer, a patterned adhesive layer, or a line array, or separate adhesive spots or other methods such as heat bonding, pressure joints, ultrasonic bonds, mechanical dynamic joints, or any other suitable joining means or combinations of these joining means as are known in the art. Representative joining methods are also described in PCT application WO 93/09741, entitled "Absorbent article having a non-woven material and a film cover with openings", published on May 27, 1993 naming Aziz and others, as inventors, and is hereby incorporated by reference. After joining a fibrous nonwoven material, the composite web may tend to be less elastomeric due to the relative inelasticity of the bonded nonwoven material. In order to make the non-woven material more elastic and to restore elasticity to the composite laminate, the composite web can be processed by elasticized methods and apparatuses to elasticize "zero stress" laminates by incremental stretching, as disclosed in the aforementioned Buell patent and 5,151,092, as well as the aforementioned patents Weber and others 5,167,897, Buell and others 5,156,793, and Weber et al., 5,143,679. The composite "zero tension", resulting elasticized fabric then has a soft feel similar to the fabric for prolonged use and comfortable fit in an absorbent garment. The side panels 420 can be attached to the diaper in any suitable manner known in the art. For example, as shown in Figure 13, the side panels 420 can be fixed directly to the backsheet 402 by the attachment means (not shown) such as an adhesive or any other attachment means as is known in the art. A particularly preferred configuration for side panels 420 is shown in Figure 14, a configuration that is more fully disclosed in the commonly assigned, co-pending United States patent applications Serial No. 08 / 707,345, by LaVon et al., Filed on September 3, 1996, and 08 / 155,048, filed on November 19, 1993, the disclosures of both being incorporated herein by reference. As shown in Figure 14 the side panel 420 is preferably composed of two frames or strips 421 and 422. The strips 421 and 422 can be two discrete strips, or alternatively, these can be formed by bending a single strip on the edge front 424, and moving the lengths of the two resulting strips in a non-parallel manner. If two discrete strips are used, these can be joined as with suitable adhesive, one to the other at the leading edge 424, and can be simultaneously attached to the tape tab 423. The side panel 420 can be attached to the back sheet 402 at the joining area 425 by any suitable manner, and particularly as disclosed in the Lavon and other patent application 08 / 707,346 and others mentioned above. Although it is not necessary for the pairs of side panels to be identical, they are preferably mirror images of one another. Tape fasteners, for example, tape tab 423, are typically applied to at least a pair of elastomeric side panels 420 to provide a fastening means for holding the diaper on the wearer. The tape tab fasteners may be any of those well known in the art such as the fastening tape disclosed in Patent No. 5, Buell, 151, 092 mentioned above and Buell United States Patent No. 3,848,594 issued November 19, 1974, the disclosure of which is hereby incorporated by reference. Other elastic members (not shown) of the present invention may be disposed adjacent the periphery of the diaper 400. The elastic members are preferably along each longitudinal edge 403, such that the elastic members tend to pull and hold the elastic. diaper 400 against the legs of the wearer, furthermore, the elastic members may be disposed adjacent either or both of the end edges 401 of the diaper 400 to provide a waistband as well as or instead of the leg cuffs. For example, a suitable waistband is disclosed in U.S. Patent No. 4,515,595 to Kievit et al. Issued May 7, 1985, the disclosure of which is hereby incorporated by reference. In addition, a suitable method and apparatus for making a disposable diaper having elastically contractible elastic members is disclosed in Buell's United States Patent No. 4,081,301, issued March 28, 1978, the disclosure of which is hereby incorporated here by reference. The resilient members are secured to the diaper 400 in an elastically contractible condition so that in a normally non-loosening configuration, the elastic members will actively contract or collect the diaper 400. The elastic members can be secured in an elastically contractible condition at less two ways. For example, the elastic members can be stretched and secured while the diaper 400 is in an uncontracted condition. In addition, the diaper 400 can be contracted, for example, by folding it and the elastic members secured and connected to the diaper 400 while the elastic members are in either the relaxed or unstretched condition. The elastic members may extend along a portion of the length of the diaper 400. Alternatively, the elastic members may extend the total length of the diaper 400 or any other suitable length to provide an elastically contractible line. The length of the elastic members is dictated by the design of the diaper. The elastic members can be in a multitude of configurations. For example, the width of the elastic members can be varied from about 0.25 mm to about 25 mm or more; the elastic members may comprise a single strand of elastic material may comprise several parallel or non-parallel strands of elastic material; or the elastic members may be rectangular or curvilinear. Still further, the elastic members may be secured to the diaper in any of several ways known in the art. For example, the elastic members can be ultrasonically bonded, sealed with heat and pressure on the diaper 400 using a variety of bonding patterns, or the elastic members can simply be glued to the diaper 400. As shown in Figure 13, the absorbent core 406 preferably includes a fluid distribution member 408. In a preferred configuration as illustrated in Figure 13, the absorbent core 406 preferably further includes an acquisition layer or members 410 in fluid communication with the fluid distribution member 408. and located between the fluid distribution member 408 and the back sheet 404. The acquisition layer or member 410 may be composed of several different materials including woven or nonwoven webs of synthetic fibers including polyester, polypropylene or polyethylene, of fibers natural products that include cotton or cellulose, a mixture of these fibers or any of the equivalent materials or combinations of these materials. In use, the diaper 400 is applied to a wearer by placing the posterior waistband region under the wearer's back, and pulling the remainder of the diaper 400 between the wearer's legs such that the front waistband region is placed across the user's center The elastomeric side panels are then extended as necessary for comfort and fit, and then the tape tab or other fasteners are preferably secured to the outside-facing areas of the diaper 400. By having side panels 420 comprising an elastomeric weft of the present invention, the diaper can be adapted for different sizes of children, for example, in a way to provide a tight fit, comfortable, with breathability. Although a disposable diaper is shown as a preferred embodiment of a garment comprising an elastomeric fabric of the present invention, this disclosure does not imply that it is limited to disposable diapers. Other disposable garments may also incorporate an elastomeric weft of the invention in various parts to provide additional comfort, fit and breathability. Also, it is contemplated that even durable garments such as undergarments and swimwear may benefit from the durable, porous, extensible features of an elastomeric fabric of the present invention. A multilayer film 120 to the present invention can be processed using conventional methods to produce multilayer films in conventional co-extruded film manufacturing equipment. In general, polymers can be melt processed into films using either film casting or extrusion blow molding methods both of which are described in "Plastics Extrusion Technology" -2nd ed., By Alian A. Groff ( Van Nostrand Reinhold-1976), which is hereby incorporated by reference. The cast film is extruded through a linear slot die. Generally, the flat web is cooled on a large polished metal roll in motion. This quickly cools and stops the first roller, passes over one or more auxiliary rollers, then through a closure of sheaves covered with rubber or "drag" rollers and finally to a winder. In the extrusion of the film by blowing the molten material is extruded upwards through a thin annular side opening. This process is also required as tubular film extrusion. The air is introduced through the center of the die to inflate the tube and make it expand. A mobile bubble is formed in this way, which is maintained at a constant size by control of the internal pressure of the air. The tube of the film is cooled by air blowing through one or more cooling rings that surround the tube. The tube is then collapsed or crushed by pulling it into a flattened frame through a pair of drive rollers and into a wire feeder. A co-extrusion process requires more than one extruder and either a multi-distribution matrix system or co-extrusion feed block or combinations of the two to achieve the structure of the multilayer film. U.S. Patent Nos. 4,152,387 and 4,197,069, issued May 1, 1979 and April 8, 1980, respectively, both to Cloeren, are hereby incorporated by reference, disclose the principle of feed block extrusion. . The multiple extruders are connected to the feed block which employs movable flow dividers to proportionally change the geometry of each individual flow channel in direct relation to the volume of the polymer passing through the flow channels. The flow channels are designed such that at their point of coefficient, the materials flow together at the same velocity and flow pressure eliminating interfacial tension and flow instabilities. Once the materials are attached to the feed block, they flow into an individual distribution matrix as a composite structure. It is important in this process that the melt viscosities and the melting temperatures of the material do not differ so widely. Otherwise, flow instabilities can result in the matrix that derives from a poor contour of the thickness distribution of the layer in the multilayer film. An alternative to the feed block coextrusion is a multi-blade or multi-tube array as disclosed in the aforementioned U.S. Patent Nos. 4,152,387, 4,197,069 as well as in U.S. Patent No. 4,533,308. , issued August 6, 1985 to Cloeren, hereby incorporated by reference. Considering that the melting currents of the feed block system are conducted together outside and before entering the body of the die, in a die of blades or multiple distribution pipe, each melted stream has its own distribution pipe in the die where the polymers are spread independently in their respective distribution tubes. The molten currents are brought close to the die outlet with each stream melted to the total width of the die. The movable blades provide the ability to adjust the output of each flow channel in direct proportion to the volume of material flowing through it, allowing the molten material to flow along with the same linear flow rate, pressure and desired width. Since the properties of molten flux and the melting temperatures of polymers vary widely, the use of a blade die has several advantages. The die itself has suitable technical isolation characteristics where widely differing melting temperature polymers, for example, up to 175 ° F (80 ° C), can be processed together.

Each distribution tube in a blade die can be designed and made for a specific polymer. In this way, the flow of each polymer is influenced only by the distribution design, and no forces are imposed by other polymers. This allows materials with widely different melt viscosities to be co-extruded into multi-layer films. In addition, the blade die also provides the ability to make the width of the individual distribution tubes, such that an inner layer can be completely enclosed by the outer layer leaving no exposed edges. The aforementioned patents also disclose the combined use of the feedblock and turntable die systems to achieve more complex multi-layer structures. The multilayer films of the present invention can comprise two or more layers, at least one of the layers being elastomeric. Although an elastomeric layer is generally substantially bonded to one or two cover layers, it is contemplated that multiple elastomer layers may be used, each elastomeric layer being attached to one or two cover layers. The three-layer films, such as the multilayer film 120 shown in Figure 4, preferably comprise a central elastomeric core 101 which may comprise from about 10 to 90% of the total thickness of the film. The outer cover layers 103 are generally, but not necessarily identical, and may comprise from about 5 to 45% of the total thickness of the film. The tie layers, when employed, can each comprise from about 5 to 10% of the total thickness of the film. In a three layer film, the core layer 101 has first and second opposite sides, one side being substantially continuously joined to one side of each outer cover layer 103 prior to the application of the applied tension of the weft.

After the multilayer elastomeric film has been co-extruded it is preferably fed to a perforation and cooling forming structure, thus producing a three-dimensional, macroscopically expanded elastomeric aperture screen of the present invention. In general, the film can be formed by drawing this film against a forming screen or other average vacuum forming structure and passing a stream of air or water over the surface disposed outwardly of the film. These processes are described in the aforementioned Radel patent, as well as in U.S. Patent No. 4,154,240, issued to Lucas et al., Both incorporated herein by reference. The formation of a three-dimensional elastomeric web may alternatively be achieved by applying a liquid stream with sufficient force and mass flow to cause the formation of the web as described in commonly assigned U.S. Patent No. 4,695,422, issued to Curro et al., and incorporated herein by reference. Alternatively, the film may be formed as described in commonly assigned U.S. Patent No. 4,552,709 to Koeger et al. And is hereby incorporated by reference. Preferably, the elastomeric web is expanded and perforated in a macroscopically uniform manner by the method of supporting the forming structure in a fluid pressure differential region by a fixed support member as taught by the commonly assigned United States patent No 4,878,825 and 4,741, 877, both by Mullan, Jr., and incorporated herein by reference. Although not shown, the process of the present invention, using a conventional information screen having a woven wire support structure, would also form a weft within the scope of the present invention. The knuckles of a woven wire forming screen would produce a three-dimensional weft, macroscopically expanded that has a pattern of undulations on the first surface, the undulations corresponding to the knuckles of the screen. However, the undulations would generally remain in the plane of the first surface, away from the plane of the second surface. The cross section of the interconnecting members would remain concave in shape generally upward with the interconnecting side walls of the interconnecting members terminating to form the secondary openings substantially within the plane of the second surface. A particularly preferred forming structure comprises a laminated, photo-etched structure as shown in Figure 15, which shows a perspective illustration, partially segmented, enlarged, of a photo-etched laminate structure of the type used to form plastic wefts of the type generally illustrated in FIG. Figure 2. The laminated structure 30 is preferably constructed in a general manner according to the teachings of the aforementioned Radel and others patent and is composed of individual sheets 31, 32 and 33. A comparison of Figure 3 with the elastomeric weft 80 shown in Figure 2 reveals the correspondence of the primary aperture 71 in the plane 102 of the elastomeric weft 180 to the aperture 61 in the uppermost plane 62 of the photo-etched laminate structure 30. Likewise, the aperture 72 in the plane 106 of the elastomeric web 80 corresponds to the opening 63 in the lowermost plane 64 of the laminated structure photogram 30. The uppermost surface of the photo-etched laminate structure 30, located in the uppermost plane 72, may be provided with a microscopic pattern of protuberances 48 without departing from the scope of the present invention. This is preferably achieved by applying a resistive coating, which corresponds to the desired microscopic pattern of the surface aberrations on the upper side of a flat photo etched sheet 31 and subsequently initiates a second gravure process. The second gravure process produces a sheet 31 having a pattern of microscopic protrusions 48 on the uppermost surface of the interconnected elements defining the pentagonally formed openings, for example, the aperture 41. The pattern of microscopic protuberances does not substantially remove the first surface of the plane of the first surface. The first surface is displayed on a macroscopic scale, while the protuberances are perceived on a microscopic scale. The construction of a laminated structure employing such pattern of protuberances 48 on its uppermost layer is disclosed in general manner in U.S. Patent No. Ahr et al., Mentioned above. The process for constructing the laminated structures of the type generally disclosed in Figure 2 are described in the aforementioned Radel and others patent. The photo-etched laminated structures are preferably rolled by conventional techniques into a tubular forming member 520, as generally illustrated in Figure 16 and their opposite ends generally bonded with the teachings of Radel and others to produce a seamless tubular forming member 520. The outermost surface 524 of the tubular forming member 520 is used to form the multilayer elastomeric web brought into contact therewith while the innermost surface 522 of the tubular member is generally not in contact with the plastic web during the forming operation. The tubular member may, in a preferred embodiment of the present invention, be employed as the shallow embossing / perforating forming cylinder or perforation cylinder 555 in a process of the type described in detail in the aforementioned Lucas et al. Patent. A particularly preferred apparatus 540 of the type disclosed in said patent is shown schematically in Figure 17. This includes embossing and perforating means 543, and constant tension film winding and advancing means 545, which, if desired, are substantially identical and function substantially identically to the corresponding portions of the apparatus shown and described in the United States Patent. No. 3,674,221 issued to Riemersma on July 4, 1972 and which is hereby incorporated by reference. The frame, the bearings, supports and the like which may be necessarily provided with respect to the functional members of the apparatus 540 are not shown or described in detail in order to simplify and represent and more clearly disclose the present invention, this being understood that these details It would be obvious to people of ordinary experience in the technique of designing plastic film conversion machinery. Briefly, the apparatus 540 schematically shows a Figure 17, comprises means for continuously receiving a plastic film belt 550 from the co-extruder 559, for example, and converting it into a perforated low-relief film 551. The film 550n is preferably supplied with Directly from the coextrusion process while still above its thermoplastic temperature to be formed with vacuum before cooling. Alternatively, the film 550 can be heated by directing jets of hot air against a surface of the film, while vacuum is applied adjacent to the opposite surface of the film. In order to maintain sufficient control of the film 550 to substantially obviate wrinkles and macroscopically distension of the film, the apparatus 540 comprises a means for maintaining constant tension in the machine direction in the film both upstream and downstream of an area. where the temperature is higher than the thermoplastic temperature of the film, but in which zone there is a tension substantially zero in the machine direction and in the transverse direction of the machine which tends to macroscopically distend the film. Tension is required to control and smooth a running thermoplastic film tape; the zone of zero tension results from the film in the area that is at a sufficiently high temperature to allow embossing in low relief and perforation of the film.

As can be seen in Figure 17, the means for embossing and perforating 543 include a rotary mounted embossing cylinder 555 having closed ends 580, a non-rotating triple vacuum distribution tube assembly 556 and optional hot air jet means (not shown). The triple vacuum distribution pipe assembly 546 comprises three designated distribution pipes 561, 562, and 563. Also shown in Figure 17 is a power-swiveled turning / cooling roll 556 and a smooth surface roll 557, (e.g. , low density neoprene), which is driven with the cooling roller. In summary, providing the means (not shown) for independently controlling the degree of vacuum in the three vacuum distribution tubes, a film thermoplastic tape running circumferentially around a part of the embossing cylinder in a low relief-perforation 555 is sequentially subjected to a first level of vacuum by the distribution tube 561, a second level of vacuum by the distribution tube 562, and a third level of vacuum by the distribution tube 563. As will be described more fully below, the Vacuum applied to the film by the distribution tube 561 allows maintaining tension upstream, in the film, the vacuum applied by the distribution tube 562 allows the film to be perforated, and the vacuum applied by the distribution tube 563 allows the cooling of the the film below its thermoplastic temperature and allows to establish the voltage downstream there. If desired, the surface that is in contact with the embossed-perforated embossing cylinder film 555 may be preheated before reaching the vacuum distribution tube 562 by means well known in the art, and therefore not shown. to facilitate the best conformation of the plastic film composed of flow-resistant polymers during the embossing operation in low relief. The gripping space 570 intermediate the cooling roller 566 and the soft surface roller 567 is only nominally loaded because the high pressure would smooth the three dimensional undercuts that were formed in the film in the aforementioned manner. However, even the nominal pressure in the grip space 570 aids the vacuum applied by the distribution tube 563 to isolate the downstream voltage (i.e. the tension of the winder roller) from the low relief / perforated part of the cylinder. 555 embossed-perforated embossing pattern, and allows the 570 grip space to separate the film with the low relief and perforated embossing cylinder in low relief-perforated 555. Moreover, while the vacuum attracts the passing ambient air through the film to the distribution tube 563 which will normally cool the film below its thermoplastic temperature, the passage of the refrigerant through the cooling roller as indicated by arrows 573, 574 in Figure 17 will allow the apparatus to handle thicker films or be operated at higher speeds. The low relief and perforated means 543, comprise the low-relief, perforated cylinder, rotatably mounted, means (not shown) for rotating the cylinder 555 at a controlled peripheral speed, the non-rotating triple vacuum distribution tube assembly 556 within the low relief-perforated cylinder 555, means (not shown) for applying controlled levels of vacuum within the three vacuum distribution tubes 561, 562, and 563 comprising the triple distribution tube assembly 556, and the means optional hot air jet (not shown). The low-relief-perforated cylinder 555 can be constructed generally following the teachings of the aforementioned Lucas and others patent, but replacing a tubular lamination forming surface of the present invention with the perforated tubular forming surface disclosed therein. To sum up, the first vacuum distribution tube 561, and the third vacuum distribution tube 563 located within the low-relief-perforated cylinder 555 substantially maintain the constant voltage upstream and downstream, respectively in a running film belt while that the intermediate part of the film adjacent to the second vacuum distribution tube 562 within the low relief cylinder and a perforation 555 is subjected to the stress that vitiates the heat and vacuum to effect embossing and perforation of the movie. Although a preferred application of the disclosed photogravure laminate structure is in a vacuum film forming operation as generally outlined in the aforementioned commonly assigned patent issued to Lucas et al., It is anticipated that the photoetched laminate forming structures of the present The invention may be employed with equal ease to directly form a three-dimensional plastic structure of the present invention. This procedure would involve applying a hot fluid plastic material, typically a thermoplastic resin, directly to the forming surface by applying a sufficiently large pneumatic differential pressure to the hot fluid plastic material so that the material conforming to the surface image of the formation of the perforated laminate, allowing the fluid material to solidify, and subsequently removing the three-dimensional plastic structure from the forming surface. Although the mode of the frame generally disclosed in Figure 2 represents a particularly preferred embodiment of the present invention, any number of interconnecting members may be employed within the frame structures of the present invention, eg, secondary, tertiary, etc. An example of this structure is shown in Figure 18, which also shows a variant of the cross sections of the interconnection members concave upwardly. The aperture network shown in Figure 18 comprises a primary aperture 301 formed by a multiplicity of primary interconnecting elements, for example, elements 302, 303, 304 and 305 interconnected to each other in the uppermost plane 307 of the frame 300, said opening further being subdivided into minor secondary openings 310 and 311 by the secondary interconnecting members 313 in an intermediate plane 314. The primary opening 310 is further subdivided by the interconnecting member 320 into even smaller secondary openings 321 and 322, respectively, in still the lower plane 325 of the frame 300. As can be seen from Figure 19, which is taken along the section line 19-19 of Figure 18, the planes 314 and 325 are generally parallel a and are located intermediate to the uppermost plane 307 and to the uppermost plane 330. In the embodiment of the frame illustrated in Figure 17 and 18, the primary interconnection members and Secondary members are further connected to the interconnecting tertiary members intersecting, for example, the tertiary interconnecting members 320, which also exhibit a generally concave-shaped cross section upwards along their length. The intersecting primary, secondary and tertiary interconnecting members terminate substantially concurrently with one another in the plane 330 of the second surface 332 to form a multiplicity of openings or openings in the second surface of the frame, for example, the openings 370, 371 and 372., It is clear that the interconnected primary, secondary and tertiary interconnecting members located between the first and second surface of the frame 300, form a closed network connecting to each of the primary openings, for example, the opening 301 on the first surface 331 of the frame, with a multiplicity of secondary openings, for example, the openings 370, 371 and 372, on the second surface 332 of the second frame. As will be appreciated, the interconnection members with generally concave upward shape, used in the frames of the present invention may be substantially straight along their entire length. Alternatively, these may be curvilinear, these may comprise two or more substantially straight segments or these may otherwise be oriented in any desired direction along any part of their length. There is no requirement that the interconnection members be identical to one another. In addition, the aforementioned shapes can be combined in any desired manner to produce any desired pattern. Regardless of the finally selected shape, the concave upwardly-shaped cross-section that exists along their respective lengths of the interconnected interconnecting members helps impart resilience to the elastomeric webs of the present invention, as well as three-dimensional remoteness. It would be obvious to those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the present invention. For example, in the event that it is desired to produce frames of the present invention where a previously determined part of the frame is capable of preventing the transmission of flow, it is feasible to perform the low relief operation without causing breakage of the frame in its second surface. The commonly assigned U.S. Patent No. 4,395,215 issued to Bishop on July 26, 1983 and the commonly assigned U.S. Patent No. 4,747,991 issued to Bishop on May 31, 1988, each of which are for the present incorporated herein by reference, fully disclose how to construct tubular forming structures that are capable of producing expanded three-dimensional films that are embossed in low relief in a uniform manner, but perforated only in previously determined areas. It is believed that the description contained herein will allow one skilled in the art to practice the present invention in many and varied ways. However, the following exemplary embodiment and analytical method is established for the purpose of illustrating the beneficial reliability of a particularly preferred elastomeric web of the present invention.

EXAMPLE A flat coextruded multilayer film was produced, and then formed by the methods disclosed above in an elastomeric web of the present invention, generally as shown in the photomicrographs of Figures 9 to 11. The coextruded film comprised three layers as it is illustrated in Figure 4, with the elastomeric layer comprising a three-block styrenic copolymer and the cover layers comprising a polyolefin material. The total caliper of the film was approximately 0.09 mm with the elastomeric layer being approximately 75 to 90% of the thickness before forming in a three-dimensional elastomeric web. Although being difficult to measure accurately, the gauge of the three-dimensional elastomeric web from the first surface to the second surface was of the order of one millimeter for a stretch ratio of about 10: 1. In a non-extended configuration, as it is formed, the first continuous surface generally formed a regular pattern of one m2 of fluid-permeable openings spaced about 1 mm apart on all sides. The secondary openings were slightly smaller than the primary openings, giving the elastomeric web an open-open area of approximately 12 to 16%. An exemplary elastomeric web of the present invention exhibited safe elastic performance by repeated and sustained web tensions of up to about 400% or more without significantly affecting the elasticity or porosity of the web. In general, the weft exhibited a superior modulus in the first extension as the cover layers experienced non-elastic stress. Subsequently, it is believed that the microscopic roughnesses formed on the interconnection members in the stress regions of the non-elastic cover layer, which resulted in a lower and generally constant modulus of the weft. In a particularly preferred method of characterizing the desirable elastic behavior of the exemplary elastomeric weft, a notch stress test was used by the analytical method below to determine the work of the rupture characteristics. The breaking work is essentially the area under the stress-strain curve produced while undergoing stress from zero stress to breakage. This analytical method, as outlined below, was chosen to be especially useful in understanding the sensitivity of the notch of the exemplary elastomeric web and its ability to withstand catastrophic failure due to the propagation of the notch during extension. Samples of the exemplary elastomeric web of the present invention required more than 40 kg-mm to break. By way of example, when the samples of the flat non-perforated coextruded film used to form the exemplary three-dimensional screen were tested by the same analytical method they required only about 8 kg-mm on average to break.

ANALYTICAL METHOD The following is a representative analytical method which has been found to be suitable for determining the performance of the porous elastomeric webs according to the present invention. Notch Stress Test This test method is based on ASTM D882-83 and measures the characteristics of the work to break out of the films or frames with openings, with notches. The method is applicable to a wide range of polymeric films, frames and composite structures. Hardware Components Electronic voltage tester: A voltage tester with a universal constant coefficient calibrated for elongation under tension and data collection capacity is required. The tester must be equipped with a suitable load cell to measure the voltage load within 25 to 75% of the capacity of the load cell and facilitate data collection. The tester must be equipped with clamping jaws designed to test the frame in such a way that the failure of the frame in the test occurs within the frame and not at the point of attachment. The proper equipment is well known in the art, and can be obtained from Instron Engineering Corp., Canton MA, or SINTECH-MTS Systems Corp., Eden Prairie, MN. Software Components Job calculation to break: You can use computer software to work to break. The Software calculates the area under the stress / strain curve that exits the voltage tester, and can be accomplished in various ways known in the art. For example, the value for the work to break can be calculated by integrating on the stress / strain curve produced by the voltage tester. In the alternative, work to break can be manually calculated in any manner known in the art to find the area under a geometric curve. Preparation of instrumentation and test sample Crosshead speed: 20 inches / minute Gauge length: Samples of the weft material are prepared in strips 1 inch wide, gauge length 2 inches. Mouting: Each sample of the weft material is cut, with a new shaving blade making a half-inch-long transverse slit through the openings near the midpoint of the gauging length. Procedure The sample of the notched screen is inserted into the jaws of the calibrated and loaded voltage tester to eliminate any looseness in the sample. The notched sample is then pulled to the fault while the data collection device records the stress / strain data and the work calculations are obtained to break.

Claims

1. - A porous, three-dimensional, macroscopically expanded web having a first continuous surface and a second discontinuous surface, said first surface and said second surface being located in substantially parallel planes that are remote from one another, characterized in that the web is elastomeric, said elastomeric web comprising a multiplicity of elastomeric interconnecting members of concave-shaped cross-section to substantially decouple the stresses induced by the applied stress on the first surface of the second surface, said interconnecting members defining at least one primary aperture in said first surface and having interconnected sidewall portions extending in the direction of the second surface, said wall portions laterally connected and terminating to form at least one secondary opening having tear-start sites in the second surface of the elastomeric web, such that stresses induced by stress on the elastomeric web are substantially decoupled from the tear initiation sites in the secondary openings, at least until the second surface is no longer remote from said web. plane of the first surface when stresses are applied to the frame.

2. A screen according to claim 1, further characterized in that the screen comprises a film formed, the film formed preferably comprising at least one substantially elastomeric layer having a first side and a second side and at least one, and more preferably at least two, substantially less elastomeric jacket layers substantially continuously joined to the substantially elastomeric layer prior to the application of the stresses to the web.

3. - A frame according to claims 1 or 2, further characterized in that the frame includes at least one intermediate interconnection member in an intermediate plane to the first and second surfaces, such that at least one of said primary openings in said The first surface of the screen is in fluid communication with at least two secondary openings in said second surface of the screen.

4. A frame according to any of the preceding claims, further characterized in that said interconnecting members exhibit rugosities generally oriented transversely.

5. A screen according to any of the preceding claims, further characterized in that the screen includes a non-woven fibrous material attached to at least parts of at least one surface of the screen, such that the screen and the non-woven material they form a composite laminate.

6. A method for making a three-dimensional, macroscopically expanded elastomeric web having a first continuous surface and a second discontinuous surface remote from the first surface, the method being characterized by the steps of: (a) providing an elastomeric layer film multiples having a thickness, preferably by co-extrusion, said multilayer film preferably including at least one elastomeric layer and at least one cover layer, and more preferably comprising at least one elastomeric layer that is disposed between at least two layers covering. (b) Holding the multilayer film on a forming structure having exposed surfaces, said forming structure exhibiting a multiplicity of openings which place the exposed surfaces of the forming structure in fluid communication with each other; said forming structure moving in a direction parallel to the direction of travel of the multilayer film and leading to the multilayer film in said direction; and (c) Apply a fluid pressure differential across the thickness of the multilayer film along the direction of movement of the formation structure, the fluid pressure differential being large enough to cause the multi-layer film to conform to the forming structure and break in at least a portion of those areas that coincide with the openings in the forming structure.

7. A method according to claim 6, said method further characterized in that it includes the additional steps after step c) of: (d) providing at least one fibrous nonwoven web material; (e) joining the nonwoven web material to the elastomeric web, such that the non-woven web material and the elastomeric web form a composite laminate; and (f) incrementally stretching the composite laminate to impart elasticity to the composite laminate.

8. A garment having elastomeric portions characterized in that the elastomeric portions comprise a macroscopically expanded, porous, three-dimensional elastomeric web having a first continuous surface, and a second discontinuous surface, said first surface and said second surface being located in planes substantially parallel, which are spaced apart from one another, said elastomeric web having a multiplicity of elastomeric interconnecting members of concave-shaped cross section upwardly to substantially decouple the stresses induced by the applied stress on said first surface of said second surface, the interconnecting members defining at least one primary opening in said first surface and having interconnected side wall portions extending in the direction of the second surface, the interconnected wall portions terminating to form at least one secondary opening having tear initiation sites in said second surface of the elastomeric web, such that stresses induced by stress on the elastomeric web are substantially decoupled from the tear initiation sites in said secondary apertures, thus less until the second surface is no longer far from the plane of the first surface when the tension is applied to the web.

9. A garment in accordance with claim 8, further characterized in that the garment is disposable, said garment being preferably a disposable diaper.

10. A garment according to claim 8 or 9, further characterized in that said garment includes elastomeric side panels, the elastomeric side panels comprising said elastomeric web.