CA2265451A1 - Elastic necked-bonded materials and methods of forming the same - Google Patents

Abstract

A method of forming a stretchable composite by applying a polymeric precursor (26), such as a latex or thermoset elastomer, to a neckable material (12) either prior to or after neck-stretching the material, then treating the polymeric precursor (26) on the necked material to form a polymeric tie layer (27). An elastic sheet (32) is bonded to the tie layer and necked-stretched material thereby forming an elastic necked-bonded laminate (44).

Description

?CA 02265451 1999-03-09W0 98/ 16678 PCTIU S97/ 18561ELASTIC NECKED-BONDED MATERIALS AND METHODS OF FORMING THE SAMEFIELD OF THE INVENTIONThe present invention relates to methodsof forming elasticized materials. Moreparticularly, the present invention relates to elastic neck-bonded laminates, and methodsof making the same.BACKGROUNDPolymeric nonwoven webs formed by nonwoven extrusion processes such as, forexample, meltblowing processes and spunbonding processes may be manufactured intoproducts and components of products so inexpensively that the products could beviewed as disposable after only one or a few uses. Examples of such products includediapers, tissues, wipes, garments, mattress pads and feminine care products. Thereexists a continuing need for improved materials which are elastic, resilient, and flexiblewhile still having a pleasing feel. A problem in fulfilling this need is that commerciallyviable elastic materials often feel rubbery.The unpleasant tactile properties of elastic materials may be avoided by forming alaminate comprising an elastic sheet with one or more nonelastic sheets which have asoft feel. However, nonwoven webs formed from nonelastic polymers having improvedtactile properties such as, for example, polypropylene are generally considerednonelastic. The lack of elasticity usually restricts these nonwoven fabrics to applicationswhere elasticity is not required. Nevertheless, laminates of elastic and nonelasticmaterials have been made by bonding the nonelastic material to the elastic material in amanner that allows the laminate to stretch and recover yet which retains the desirabletactile properties of the nonelastic material. Elastic laminates, comprising an elasticsheet and a soft nonelastic material, are typically incorporated into products such that thesoft material will contact a persons skin or forms the outermost portion of the product.In one such laminate, a nonelastic material is joined to an elastic material whilethe elastic material is in a stretched condition so that when the elastic material is relaxed,the nonelastic material gathers between the locations where it is bonded to the elasticmaterial. The resulting composite elastic material is readily stretchable to the extent that?101520253035CA 02265451 1999-03-09W0 93/15573 PCTIUS97/18561the nonelastic material gathered between the bond locations allows the elastic material toelongate. An example of this type of composite material is disclosed, for example, byU.S. Patent No. 4,720,415 to Vander Wielen et al.Another elastic laminate known in the art includes those conventionally referred toas “neck-bonded” materials. Necked-bonded materials are generally fabricated bybonding an elastic member to a non-elastic member while the non-elastic member isnarrowed or necked. Neck-bonded laminates provide a material which is stretchable inthe necked direction, the necked direction is most commonly also the cross—machinedirection. Examples of neck—bonded laminates are described in commonly assigned U.S.Patent Nos. 5,226,992 and 5,336,545 both to Morman. in addition, "reversibly neckedmaterials” include materials which are stretchable to about the pre-necked dimensionsand which, upon release of the stretching force, substantially recover to the neckeddimensions unaided by additional materials. Such materials are typically formed bynecking the material and treating the necked material, such as by heating and cooling thematerial, in order to impart memory of the necked dimensions to the material. Reversiblynecked materials and methods of forming the same are disclosed in commonly assignedU.S. Patent No. 4,965,122 to Morman.Due to the nature of the methods of making elastic laminates, such as thosedescribed above, there exists a variety of elastic materials having the requisitecharacteristics for use in forming the elastic laminate structure. Similarly, there likewiseexists a variety of neckable materials which are suitable for use in forming the elasticlaminate structure. However, due to the variety of elastic and neckable materialspotentially used to form elastic laminates there exist certain combinations of elastic andneckable materials which, although having excellent physical characteristics, do notadhere well to the other layers of the laminate. Thus, there exists a need for neckedbonded laminates, and methods of producing the same, having improved integrity as wellas the desired tactile and elastic properties.DEFINITIONSAs used herein the term “spunbonded fibers” refers to small diameter fibers whichare formed by extruding molten thermoplastic material as filaments from a plurality offine, usually circular capillaries of a spinneret with the diameter of the extruded moltenfilaments then being rapidly reduced as described in, for example, in U.S. Patent4,340,563 to Appel et al., and U.S. Patent 3,692,618 to Dorschner et al., U.S. Patent?1015202530CA 02265451 1999-03-09WO 98/16678 PCT/US97/185613,802,817 to Matsuki et al., U.S. Patents 3,338,992 and 3,341,394 to Kinney, U.S. Patent3,502,763 to Hartman; U.S. Patent 3,542,615 to Dobo et al and U.S. Patent No.5,382,400 to Pike et al. Spunbond fibers are then usually cooled and solidified so theyare not tacky when they are deposited onto a collecting surface. Spunbond fibers aregenerally continuous and have average diameters (from a sample of at least 10) largerthan 7 microns, more particularly, between about 10 and 40 microns.As used herein the term "meltblown fibers" refers to fibers formed by extruding amolten thermoplastic material through a plurality of fine, usually circular, die capillaries asmolten threads or filaments into converging high velocity, usually hot, gas (e.g. air)streams which attenuate the filaments of molten thermoplastic material to reduce theirdiameter, which may be to microfiber diameter. Thereafter, the meltblown fibers arecooled and carried by the high velocity gas stream and are deposited on a collectingsurface to form a web of randomly disbursed meltblown fibers. Such a process isdisclosed, for example, in U.S. Patent 3,849,241 to Butin et al.As used herein “multilayer laminate” refers to a laminate having at least two layerswith one of which being a nonwoven web. For example, some of the layers can bespunbond and some meltblown such as a spunbond/meltblown/spunbond (SMS)laminate and others as disclosed in U.S. Patent 4,041,203 to Brock et al., U.S. Patent5,169,706 to Collier, et al. U.S. Patent 5,145,727 to Potts et al., U.S. Patent 5,178,931 toPerkins et al. and U.S. Patent 5,188,885 to Timmons et al. Such a laminate may bemade by sequentially depositing onto a moving forming belt first a spunbond fiber layer,then a meltblown fiber layer and last another spunbond fiber layer and then bonding toform a laminate. Alternatively, the fabric layers may be made individually, collected inrolls, and combined in a separate bonding step. Such fabrics usually have a basisweight of from about 0.1 to about 12 ounces/yd.2 (about 3.4 to about 400 g/m2), or moreparticularly from about 0.75 to about 3 ounces/yd.2 (about 25 to about 100 g/m2).Multilayer laminates may also have various numbers of meltblown layers or multiplespunbond layers in many different configurations and may include other materials likewoven layers, films or coform materials.As used herein, the term “machine direction” or MD refers to the direction in whichthe neckable material is produced. The term “cross machine direction” or CD refers tothe direction generally perpendicular to the MD.As used herein the term "microfibers" refers to small diameter fibers having anaverage diameter not greater than about 100 microns, for example, having an average?101520253035CA 02265451 1999-03-09W0 98/ 16678 PCT/US97/18561diameter of from about 0.5 microns to about 50 microns, or more particularly, microfibersmay have an average diameter of from about 2 microns to about 40 microns.As used herein, “ultrasonic bonding" refers to a process performed, for example,by passing the fabric between a sonic horn and anvil roll as illustrated in U.S. Patent4,374,888 to Bomslaeger.As used herein “thermal point bonding” involves passing a fabric or web of fibersto be bonded between a heated bonding assembly, such as a heated calender roll and aheated anvil roll. The calender roll is usually, though not always, patterned in some wayso that the entire fabric is not bonded across its entire surface, and the anvil roll isusually smooth. As a result, various patterns for calender rolls have been developed forfunctional as well as aesthetic reasons. One example of a pattern is the HansenPennings or "HP” pattern with about a 30% bond area with about 200 bonds/square inchas taught in U.S. Patent 3,855,046 to Hansen and Pennings. A new HP pattern roll hassquare point or pin bonding areas wherein each pin has a side dimension of 0.038 inches(0.965 mm), a spacing of 0.070 inches (1.778 mm) between pins, and a depth of bondingof 0.023 inches (0.584 mm). The resulting pattern has a bonded area of about 29.5%.Another typical point bonding pattern is the expanded Hansen Pennings or “EHP” bondpattern which, when new, produces a 15% bond area with a square pin having a sidedimension of 0.037 inches (0.94 mm), a pin spacing of 0.097 inches (2.464 mm) and adepth of 0.039 inches (0.991 mm). Another typical point bonding pattern designated“714” has square pin bonding areas wherein each pin has a side dimension of 0.023inches, a spacing of 0.062 inches (1.575 mm) between pins, and a depth of bonding of0.033 inches (0.838 mm) when new. The resulting pattern has a bonded area of about15%. Yet another common pattern is the C-Star pattern which has a bond area of about16.9% when new. The C-Star pattern has a cross-directional bar or “corduroy” designinterrupted by shooting stars. Other common patterns include a diamond pattern withrepeating and slightly offset diamonds with about a 16% bond area and a wire weavepattern looking similar to a window screen, with about a 19% bond area. Typically, thepercent bonding area is less than 50% of the area of the laminate and desirably variesfrom around 10% to around 30% of the area of the laminate.The term "elastic” as used herein refers to any material which, upon application ofa biasing force, is elongatable to a stretched, biased length which is at least about 160percent of its relaxed unbiased length, and which, will recover at least 55 percent of itselongation upon release of the elongating force. A hypothetical example would be a one(1) inch sample of a material which is elongatable to at least 1.60 inches and which,?101520253035CA 02265451 1999-03-09W0 98ll6678 PCTIUS97/18561upon being elongated to 1.60 inches and released, will recover to a length of not morethan 1.27 inches. Many elastic materials may be stretched by much more than 60percent of their relaxed length, for example, 100 percent or more, and many of these willrecover to substantially their original relaxed length, for example, to within 105 percent oftheir original relaxed length, upon release of the stretching force.As used herein, the term "nonelastic” refers to any material which does not fallwithin the definition of “elastic,” above.As used herein, the term “recover” refers to a retraction of a stretched materialupon termination of a biasing force following stretching of the material by application ofthe biasing force. For example, if a material having a relaxed, unbiased length of one (1)inch is elongated 60 percent by stretching to a length of 1.6 inches the material would beelongated 60 percent (0.6 inch) and would have a stretched length that is 160 percent ofits relaxed length. if this exemplary stretched material contracted, that is recovered to alength of one and two tenths (1.2) inches after release of the biasing and stretchingforce, the material would have recovered about 66 percent (0.4 inch) of its 0.6 inchelongation. Recovery may be expressed as [(maximum stretch length - final samplelength)/(maximum stretch length - initial sample |ength)] X 100.As used herein, the terms “necking” or "neck stretching” interchangeably refer to amethod of elongating a nonwoven fabric, e.g. in the machine direction, to reduce its widthin a direction perpendicular to the direction of elongation in a controlled manner to adesired amount. The controlled stretching and necking may take place under cool, roomtemperature or greater temperatures and is limited to an increase in overall dimension inthe direction being stretched up to the elongation required to break the fabric. Whenrelaxed, the web retracts toward its original dimensions. Such a process is disclosed, forexample, in U.S. Patent No. 4,443,513 to Meitner et al.; U.S. Patent Nos. 4,965,122,4,981,747 and 5,114,781 to Morman and U.S. Patent No. 5,244,482 to HassenboehlerJr. et al.As used herein, the term “neckable material" refers to any material which can benecked; that is a material that can be constricted in at least one dimension by processessuch as, for example, drawing.As used herein, the term "necked material” refers to any material which has beenconstricted in at least one dimension by processes such as, for example, drawing.As used herein the term "reversibly necked material” refers to a material whichis capable of being stretched in the necked direction to its original pre-necked dimensionsand, upon removal of the stretching force, substantially returning to the necked?1015202530CA 02265451 1999-03-09W0 98/ 16678 PCTlUS97/ 18561dimensions unaided, such as by an elastomeric sheet. Typically reversibly neckedmaterials include necked materials which have been heated and cooled while under atensioning force. The heating and cooling of the material while necked serves to impartmemory of the materia|’s necked condition.As used herein, the term "percent neckdown” refers to the ratio determined bymeasuring the difference between the un-necked dimension and the necked dimensionof the neckable material and then dividing that difference by the un-necked dimension ofthe neckable material. The ratio is then multiplied by 100.As used herein, the term "sheet” means either a film, foam or a nonwoven web.As used herein the term “layer” refers to a polymeric material which, whensupported on a substrate, may be either continuous-, e.g. a film, or discontinuous, e.g. arepeating or random pattern of discrete regions.As used herein, the term “elastic necked-bonded laminate” refers to a materialhaving an elastic layerjoined to a necked material. The elastic material may be joined tothe necked material at intermittent points or regions or may provide complete coverageof the necked material. The elastic necked-bonded laminate is elastic in a directiongenerally parallel to the direction of neckdown of the necked material and may includeone or more layers. For example, the elastic necked-bonded laminate may have neckedmaterial joined to both of its sides so that a three-layer composite elastic necked-bondedmaterial is formed having a structure of necked material/elastic material/necked material.Additional layers of elastic and/or necked material may be added. In addition, numerousother combinations of elastic material layers and necked materials may also be used.As used herein, the term "polymeric precursor” refers to a material that may betreated to produce a polymeric layer by undergoing polymerization, curing, cross-linking,coalescing, drying or evaporation of a solvent. However, the tenn “polymeric precursor”does not exclude materials containing polymers. For example, often a latex formulationwill contain polymers but the applied latex formulation does not form a solid material untildried.As used herein, the term “elastomeric precursor” refers to a material that is notelastomeric as applied but may be treated to produce an elastic layer by undergoingpolymerization, curing, cross-linking, coalescing, drying or evaporation of a solvent.However, the term "elastomeric precursor” does not exclude materials containingelastomers. For example, often a latex fomiulation will contain elastomers but theapplied latex formulation does not form an elastic material until dried.?1015202530CA 02265451 1999-03-09W0 98ll6678 PCT/US97Il856lSUMMARY OF THE INVENTIONThe aforesaid needs are fulfilled and problems experienced by those skilled in theart overcome by an elastic necked-bonded laminate made by the steps of: applying apolymeric precursor to a neckable material; necking said neckable material; and thentreating the polymeric precursor thereby forming a tie layer which is directly attached tothe necked material; and attaching an elastic sheet to the tie layer. The polymericprecursor may comprise a thermoset material which is treated by heating or a latex whichis treated by drying. In a further aspect, the polymeric precursor may be applied to theneckable material in an amount sufficient to create a tie layer of from about 1 to about100 g/m2. Further, the polymeric precursor can be applied to the neckable material eitherprior to or during necking. Preferably the polymeric precursor comprises an elastomericprecursor which forms an elastic polymer layer when treated. in addition, the elasticsheet can be brought into contact with the polymeric precursor prior to treating the sameto form the tie layer. For example, a molten elastomer may be extruded directly over theprecursor thereby forming an elastic sheet and the tie layer. Alternatively, an elasticsheet can be brought into contact with the tie layer and joined thereto by the applicationof heat and/or pressure.In a further aspect of the invention, an elastic necked-bonded laminate can bemade by the steps of: applying a polymeric precursor to a necked material; then treatingthe polymeric precursor thereby forming a tie layer which is directly attached to thenecked material; and bonding an elastic sheet to the tie layer. The polymeric precursormay comprise a thermoset material which is treated by heating or a latex which is treatedby drying. Preferably, the polymeric precursor comprises an elastomeric precursor whichforms an elastomeric polymer when treated. In addition, the precursor may be applied tothe neckable material in an amount sufficient to create an elastic tie layer of from about 1to about 100 g/m2. In a further aspect, the elastic sheet can be brought into contact withthe precursor prior to treating the same to form the tie layer. For example, a moltenelastomer may be extruded directly over a precursor thereby forming an elastic sheet andtie layer. Alternatively, an elastic sheet can be brought into contact with the tie layer andjoined thereto by the application of heat and/or pressure.?101520253035CA 02265451 1999-03-09WO 98116678 PCT/US97/18561ILIEF DESCRIPTION OF TH§__E_)RAWIN(_3_§FIG. 1 is a schematic representation of an exemplary process for forming anelastic necked-bonded composite material having a polymeric tie layer.FIG. 2 is a plan view of a neckable material under a tensioning force.FIG. 3 is a plan view of a neckable material before tensioning and necking.FIG. 3A is a plan view of a necked material.FIG. 3B is a plan view of a composite elastic necked-bonded material whilepartially stretched.FIG. 4 is a schematic representation of an exemplary process for forming anelastic necked-bonded composite material having a polymeric tie layer.FIG. 5 is a schematic representation of an exemplary process for forming anelastic necked-bonded composite material having a polymeric tie layer.FIG. 6 is a schematic representation of an exemplary process for forming anelastic necked-bonded composite material having a polymeric tie layer.FIG. 7 is a top view of a necked material having a discontinuous patterned tielayer.DETAILED DESCRIPTION OF THE INVENTIONIn one aspect of the present invention, referring to FIG. 1, a neckable material 12is unwound from a supply roll 14 and travels in the direction indicated by the arrowsassociated therewith as the supply roll 14 rotates in the direction of the arrows associatedtherewith. Those skilled in the art will appreciate that the neckable material 12 may beformed by known nonwoven extrusion processes such as, for example, meltblowingprocesses or spunbonding processes, without first being stored on a supply roll. Apolymeric precursor 26 may then be applied to the neckable material 12 prior to necking.Thereafter, the neckable material 12 is necked to the desired width and the polymericprecursor 26 treated to form a polymeric tie layer 27. An elastic material 32 may then bejoined to the tie layer 27 and the necked material 13 to from an elastic necked-bondedlaminate 44.The polymeric precursor may be applied in an amount sufficient to provide a tielayer 27 with a coverage of from about 1 to about 100 g/m2, desirably from about 2 toabout 50 g/m2 and even more desirably about 2 to about 20 g/m2. Preferred polymericmaterials and their corresponding precursors are discussed herein below in greater?1015202530CA 02265451 1999-03-09WO 98/16678 PCT/US97/ 18561detail. The polymeric precursor 26 may be applied to the neckable material 12 by any ofthe numerous techniques known in the art for printing, coating or spraying materials on asheet or fabric-like surface. The polymeric precursor 26 may be applied by variousmethods including, but not limited to, wire-wound coating bars, calendering, extrusion,spraying, direct gravure printing, knife-over-roll coating, floating-knife coating, reverse rollcoating, rotary screen coating, transfer coating and flexographic printing. Further, it willbe appreciated that the polymeric precursor may be applied in a single or successiveapplications. The polymeric precursor can be applied either directly or indirectly. Forexample, the precursor could be applied by coating the elastic sheet in a desired patternand then pressing the elastic sheet and necked material together.The desired method of applying particular polymeric precursors will vary in accordwith factors well known to those skilled in the art, such as, the flow characteristics of theprecursor, the desired thickness and gauge tolerance of the coating, line-speed and thesurface characteristics of the material being coated. Flexographic or direct gravureprinting are preferred since it is desirable to have a discontinuous layer, e.g. a patternedlayer, of precursor applied to the neckable material. In gravure, flexographic and screenprinting equipment, the printed composition is transferred to a printing transfer surfacewhich contains the printed patterns and then from the transfer surface the printingcomposition is transferred directly to the substrate.In reference to the embodiment of FIG. 1, the neckable material 12 passesthrough a nip 18 of an S-roll type drive roll arrangement 16 formed by stacked drive rolls20 and 22. A polymeric precursor 26 is applied to the neckable material 12 by a coatingassembly 24, such as a gravure-print coater. The individual rolls of the coating assembly24 rotate and guide the precursor 26 onto the neckable material 12. The polymericprecursor 26 is removed from the coater 24 by lightly pressing the precursor 26 againstthe neckable material 12 in the final nip of coating assembly 24 created with roll 22 ofdrive roll assembly 16.Penetration of the polymeric precursor typically occurs without the need foradditional means for pressing or driving the precursor into the neckable material. Forexample, although polyolefin nonwoven webs are often hydrophobic, many latexformulations include surfactants which make the latex compatible with the nonwovenmaterial and are thus readily wicked or absorbed into the web. However, in the eventfurther penetration is desired an additional pressure roll arrangement may be provided toobtain the desired penetration. Further, either the composition of the precursor may be?101520253035CA 02265451 1999-03-09W0 98l16678 PCT/US97Il856lvaried or the neckable material treated such as by corona treatment to achieve thedesired compatibility between the materials.. With porous neckable materials, such as a nonwoven web, the depth to which theprecursor 26 penetrates the neckable material 12 affects the elastic properties of thenecked-bonded laminate produced. Generally, the elastic properties of the resultinglaminate decrease as the degree of penetration of precursor 26 increases. Further, sincethe treated polymeric precursor 26 will act as a tie layer it is desirous to have asubstantial portion of the polymeric precursor located at or near the surface of theneckable material. Moreover, strikethrough of theprecursor and the resulting polymercan detract from the soft hand of the neckable material. Thus, the nip pressure shouldbe closely controlled while the precursor has not been treated to form the polymeric tielayer. In most cases, a gap will be maintained between the rolls to insure that theprecursor does not significantly penetrate into the neckable material. However,penetration of the precursor near the surface is desirable where the tie layer does notsufficiently bond to the necked material since, when treated, the resulting tie layer willform a material which is embedded in the neckable material. For example, withnonwoven materials the tie layer will often surround fibers within the web therebyproviding mechanical attachment to the web. Thus, it is preferred in such instances thatthe precursor penetrates at least one fiber thickness and preferably penetrates from 2 toabout 5 fiber thicknesses.Penetration of the precursor into the neckable material may be limited orcontrolled by various means. For example, the neckable material may be treatedimmediately after being applied to the neckable material thereby limiting the extent towhich a viscous precursor can be drawn into the neckable material. In addition, theneckable material may include a barrier to further penetration of the precursor. Forexample, the neckable material may comprise a multilayer laminate, e.g. an SMS, havingan internal meltblown layer therein which prevents strike-through and unwantedpenetration of the precursor. Nonwoven meltblown fabrics having fiber diameters lessthan 10 microns typically have very small pore structures which will often preventpenetration of the precursor. Alternatively, larger fiber diameter nonwovens with largerpore sizes may be treated with or include a repellent, such as a fluorocarbon, whichprevents penetration of the precursor into the fabric; see U.S. Patent 5,441,056 issued toWeber et al., the entire contents of which are incorporated herein by reference. In thisregard, a neckable material may be produced using multiple spunbond banks whereinone or more banks produce layers of spunbond fibers which are treated with or othenivise10?101520253035CA 02265451 1999-03-09WO 98/16678 PCTIUS97/18561incorporate the repellent and at least the last bank forms a layer of untreated fibers overthe previously laid repellent-treated fibers. The multiple layers of spunbond fibers maythen be bonded to form a coherent web capable of being necked. Thus, when theprecursor is applied to the neckable material it will penetrate only the repellent-free fiberslocated at the upper surface of the neckable material.From the drive-roll assembly 16, the neckable material 12 undergoes neck-stretching, being pulled by the pressure nip formed by a bonder-roll arrangement 36.Because the peripheral linear speed of the rolls of the drive-roll assembly 16 is controlledto be less than the peripheral linear speed of the bonder-roll assembly 36, the neckablematerial 12 is tensioned between the drive-roll assembly 16 and the bonder-roll assembly36. By adjusting the distance between and the difference in the speeds of the rollassemblies 16 and 36, the neckable material 12 is tensioned so that it necks a desiredamount. forming necked material 13.The neckable material 12 necks before reaching the treating device 30, however,necked material 13 may neck further upon heating. The distance between drive rollassemblies 16 and 36 responsible for necking the neckable material 12 should besufficient to achieve the desired neckdown. In reference to FIG. 2, a neckable material12 is necked-stretched between a first and second roll assembly 16 and 36. However,the percent neckdown increases as the neckable material travels away from the first rollassembly 16 towards the second roll assembly 36. The neckable material 12 necksapproaching equilibrium, a point at which without additional tensioning force or heatingno further necking will occur. Desirably drive roll assemblies are separated a sufficientdistance to substantially approach equilibrium. Further, it is also desirable that theprecursor (not shown) is treated, at a point along the distance between the first andsecond roll assemblies 16 and 36, such that the tie layer is not formed until after theneckable material is necked a desired amount.The relation between the original dimensions of the neckable material 12 to itsdimensions after tensioning and necking determines the approximate limits of stretch ofthe elastic necked-bonded material 44. Because the necked material 13 is able tostretch and return to its pre-necked dimensions in the cross-machine direction, the elasticnecked-bonded material 44 will be stretchable in generally the same direction that theneckable material 12 was necked.For example, with reference to Figs. 3, 3A, and 3B, if it is desired to prepare anelastic necked-bonded composite material stretchable to a 150% elongation, a width ofneckable material shown schematically and not necessarily to scale in Fig. 3 having a11?101520253035CA 02265451 1999-03-09W0 98/15578 PCT/US97/18561width “A” such as, for example, 250 cm, is tensioned by force F so that it necks down to awidth "B” of about 100 cm. The elastic precursor (not shown) is then treated to form anelastic tie layer (not shown). Further, an elastic sheet having a width of approximately100 cm is joined to the necked material and tie layer. The resulting composite elasticnecked-bonded material shown schematically and not necessarily to scale in Fig. 3B hasa width “B” of about 100 cm and is stretchable to the original 250 cm width "A" of theneckable material for an elongation of about 150% (or as discussed herein above, thematerial is stretchable to 250% of its relaxed unbiased width). The elastic limit of acontinuous elastic tie layer and/or elastic sheet need only be as great as the maximumdesired elongation of the composite elastic necked-bonded material. However, it willtypically be desirable to employ elastic materials which will readily allow the neckedmaterial to be elongated to at least its pre-necked dimensions.The necked material 13 is maintained in a tensioned, necked condition while thepolymeric precursor 26 is treated, thereby forming a tie layer 27 in intimate contact withthe necked material 13. in this regard it is important to note that due to the ability of theprecursor 26 to penetrate into the neckable material 12 when applied, treatment of theprecursor 26 forms a polymeric material which attaches to the to the necked material bybonding directly to the material and/or mechanically attaching thereto by solidifying aboutfibers at or near the surface of the necked material 13.Treatment of the precursor 26 will vary with regard to the particular precursor andthe mechanism responsible for generating the polymeric tie layer 27. For example,reactions may be induced to form thermoset materials by various means such as infraredradiation, ultrasound, ultraviolet radiation, x-ray, electron beam, etc. Polymericprecursors employing these and/or other initiators used to form a compatible polymericmaterial are believed suitable for use with the present invention. Nevertheless, the mostcommon commercially available polymeric precursors typically include thermoset andlatex formulations that are activated by heating or dried by heating or microwaves. Thus,although the particular embodiments discussed herein are directed toward use of heatset and/or latex formulations, the invention is not limited to use of such materials orprocesses employing the same.In reference to the particular embodiment depicted in FIG. 1, a precursor 26, suchas a latex or thermoset formulation, may be treated by heating the applied precursor 26in treating apparatus 30, such as an oven. In instances in which the treatment of theprecursor 26 includes heating, it will be noted that this may be performed simultaneouslywith heating the necked material to create a “reversibly necked material” as described in12?101520253035CA 02265451 1999-03-09W0 98/16678 PCT/US97l18561U.S. Patent No. 4,965,122 to Morman, the entire contents of which are incorporatedherein by reference. In addition, a heating device may have multiple temperature controlzones (not shown) so that the necking process is substantially completed to the desiredamount before significant treatment of the precursor.Still in reference to FIG. 1, an elastic sheet 32 may be unwound from a supply roll34 and fed into the nip 38 of bonder-roll assembly 36 along with the necked material 13and tie layer 27. The elastic sheet 32 is fed into the bonder-roll assembly in conjunctionwith the necked material 13 such that the elastic sheet 32 is in intimate contact with thetie layer 27. The peripheral linear speed of the elastic sheet supply roll 34 may be variedas desired. For example, the linear speed of the supply roll 34 can be substantially thesame as that of bonder-roll assembly 36 so no stretching of the elastic sheet 32 isexpenenced.The bonder-roll assembly 36 may be a patterned calender roll 40 arranged with asmooth anvil roll 42. Alternatively, a smooth calender roll may be used. It is furtherdesirable to heat the layered materials, while in direct physical contact, to a temperaturesufficient to attach the tie layer 27 and the elastic sheet 32. The particular temperatureand pressure required will vary with the specific elastic materials selected. One or bothof the calender roll 40 and the anvil roll 42 can be heated and the pressure betweenthese two rolls adjusted by well known means to provide the desired temperature andbonding pressure. Various bond patterns may be used including, but not limited to,sinusoidal dot patterns and those patterns mentioned above in connection with the pointbonding. The bond surface area on the composite elastic necked bonded material 44may approach about 100 percent and still provide an elastic laminate material with goodelastic properties. Other methods may be used to join the materials such as, forexample, ultrasonic welding, laser beams, high energy electron beams and/or by othermeans known in the art.The tie layer 27 directly attaches to the necked material 13 and, thus, providesimproved integrity to the resulting necked-bonded laminate. The integrity may be furtherimproved due to the ability to achieve better adhesion between the tie layer 27 and theelastic layer 32 as compared with that between the neckable material 13 and elasticsheet 32. However, when the tie layer is itself elastic and does not significantly penetratethe neckable material, the stretch and recovery characteristics of the resulting necked-bonded laminates are not materially degraded. Moreover, due to the nature of necked-bonded materials use of an elastic tie layer will reduce rupture of bond areas and/or thecreation of high stress points within the laminate.13?101520253035CA 02265451 1999-03-09WO 98/16678 PCT/US97I1856lAlthough use of an elastomeric precursor and elastic tie layer are preferred, it isalso possible to employ inelastic polymers as the tie layer. Such polymeric precursorscan be formed upon the necked or neckable material in a manner that does notsignificantly detract from the elastic properties of the resulting laminate. For example andin reference to FIG. 7, the tie layer 27 can be formed over the necked material 13 incontinuous sections or closely spaced columnar points that extend in a directionsubstantially perpendicular to the necked direction. Thus, where the necked-stretchedmaterial is stretched in the machine direction the tie layer would extend substantiallyparallel to the machine direction. For example, in reference to Fig. 7, the tie layer 27 cancomprise spaced columns of polymer extending in the machine direction of neckedmaterial 13. Such a pattern still allows the fabric to stretch and recover in the neckeddirection. Desirably such patterns would occupy less than about 70% of the surface areaof the single side of the treated fabric.Conventional drive means and other conventional devices which may be utilizedin conjunction with the apparatus of Fig. 1 are well known and, for purposes of clarity,have not been illustrated in the schematic view of Fig. 1. In addition, it will beappreciated by those skilled in the art that the particular process could be varied innumerous respects without departing from the spirit and scope of the invention. Forexample, the neckable material may be pre-necked and treated to remain in its neckedcondition (e.g. reversibly necked) prior to being wound on the supply roll 14. As a furtherexample, after treatment of the precursor and formation of the tie layer, the elastic sheetcould be formed directly over the coated side of the neckable material such as byextruding a film of molten elastomer thereover; see U.S. Patent No. 5,514,470 issued toHaffner et al., the entire contents of which are incorporated herein by reference. It will befurther appreciated that the method of the present invention may be used in connectionwith others known in the art to fabricate a material which is stretchable in both the cross-machine and machine direction, see U.S. Patent No. 5,116,662 issued to Morman, theentire contents of which are incorporated herein by reference. For example, theperipheral linear speed of roll 34 could be adjusted to be lower than that of roll assembly36 thereby stretching the elastic layer 32. This will give the resulting laminate stretch inboth the MD and CD directions.in addition, those skilled in the art will appreciate that other methods of tensioningthe neckable material 12 may be used such as, for example, tenter frames or otherdirectional stretcher arrangements that expand the neckable material 12 in otherdirections such as, for example, the cross-machine direction so that, after bonding to the14?1015202530CA 02265451 1999-03-09W0 98/16678 PCT/US97/18561elastomeric material to the necked material, the resulting composite elastic necked-bonded material 44 will be elastic in a direction generally perpendicular to the direction ofnecking, e.g. in the machine direction. The nonelastic material may also be gatheredprior to necking. In such instances, the tensioning force may not narrow the fabric withrespect to the gathered dimensions, however the fabric will be narrower than the fabric’soriginal pre-gathered dimensions. “Necking" is intended to cover such tensioning andnarrowing relative to the pre-gathered dimensions.The neckable material 12 may be a knit, loosely woven or nonwoven materialsuch as, for example, spunbonded web, meltblown web, coforrned webs or bondedcarded webs. if the neckable material is a nonwoven web, it may include microfibers.The neckable material may be any porous material that can be necked. The neckablematerial 12 may be made of fiber forming polymers such as, for example, polyesters,polyamides and polyolefins. Exemplary polyolefins include one or more of polypropylene,polyethylene, ethylene copolymers, propylene copolymers, and butene copolymers.Useful polypropylenes include, for example, polypropylene available from the ExxonChemical Company under the trade designation Exxon 3445, and polypropyleneavailable from the Shell Chemical Company under the trade designation DX 5A09.Polyamides which may be used in the practice of this invention may be any polyamideknown to those skilled in the art including copolymers and mixtures thereof. Particularlycommercially useful polyamides are nylon-6, nylon 6,6, nylon—11 and nylon-12. Thesepolyamides are available from a number of sources such as Emser Industries of Sumter,South Carolina (Grilon® & Grilamid® nylons) and Atochem lnc. Polymers Division, ofGlen Rock, New Jersey (Rilsan® nylons), among others.In one embodiment of the present invention, the neckable material 12 may itselfcomprise a multilayer laminate having, for example, at least one layer of spunbondedweb joined to at least one layer of meltblown web, bonded carded web or other suitablematerial. For example, neckable material 12 may be a multilayer material having a firstlayer of spunbonded polypropylene having a basis weight from about 3.5 to about 270g/m2, a layer of meltblown polypropylene having a basis weight from about 3.5 to about135 g/m2, and a second layer of spunbonded polypropylene having a basis weight ofabout 3.5 to about 270 g/m2. Alternatively, the neckable material 12 may be single layerof material such as, for example, a spunbonded web having a basis weight of from about3.5 to about 340 g/m2 or a meltblown web having a basis weight of from about 3.5 toabout 270 g/m2.15?101520253035CA 02265451 1999-03-09W0 98/16678 PCT/US97/18561The neckable material 12 may also be a composite material made of a mixture oftwo or more different fibers or a mixture of fibers and particulates. Such mixtures may beformed by adding fibers and/or particulates to the gas stream in which meltblown orspunbond fibers are carried so that an intimate entangled commingling of meltblown orspunbond fibers and other materials occurs prior to collection of the fibers upon acollecting device to form a coherent web of randomly dispersed fibers and othermaterials. Examples of such materials include, but are not limited to, wood pulp, staplefibers and particulates such as, for example, hydrocolloid (hydrogel) particulatescommonly referred to as superabsorbent materials.If the neckable material 12 is a nonwoven web of fibers, the fibers should form acoherent web structure which is able to withstand tensioning and the resulting necking.The coherent web structure may be produced by bonding or entanglement betweenindividual fibers which is inherent in the meltblown process. For materials which do notinherently form a coherent web, processes such as, for example, hydraulic entangling,point bonding, through-air bonding or needlepunching may be used to impart the desireddegree of integrity. Alternatively or additionally a bonding agent may be used to achievethe desired bonding.The precursor may comprise any material which may be applied to the neckablematerial and subsequently treated to induce drying, polymerization, cross-linking or thelike, to form a polymeric sheet or layer. Preferably the precursor, once treated, forms anelastic polymer. In this regard a great variety of polymers and/or elastomers are knownin the art such as, for example, polyurethanes, silicone rubbers, poly(isobutylene-isoprene), poly(styrene-butadiene), poly(acrylonitrile-butadiene), polychloroprene,polyisoprene, polysulfides, poly(ethylene-propylene-diene), chlorosulfonatedpolyethylene, polysiloxanes, poly(fluorinated hydrocarbon), poIy(acrylate-butadiene),poly(styrene-ethylene/butylene-styrene). In one aspect of the invention, the elastomericprecursor may comprise a thermoset material which, in accord with the historical meaningof the tem, cross-links upon heating. However, elastomeric precursors may also includematerials which fall under the broader understanding of thermoset materials such asthose in which further polymerization, cross-linking or curing is induced by means otherthan heat, such as by UV irradiation, infrared irradiation, ultrasound as well as othermethods known in the art.Latex formulations, including those for thermoplastic elastomers, may also beused in the present invention. With latex formulations, a tie layer is not formed until suchtime as the emulsion is treated, which typically consists of driving off or evaporating16?101520253035CA 02265451 1999-03-09W0 98/16678 PCT/US97/18561water. In addition, elastomeric precursors capable of fonning open and closed cellelastic foams. an example being a latex foam rubber, can also be used in connectionwith the present invention. As an example, some polyurethanes give off CO2 gas whenthey react which acts to form a closed cell foam elastomer.Typically the precursor will be compounded to reduce costs and improveprocessing and therefore the specific formulations will vary with regard to the manner ofapplication and mechanism for drying, polymerization, curing and/or cross-linking of theprecursor. Formulations for calendering po|y(styrene-butadiene) and polychloroprenesare discussed in the Encyclopedia of Polymer Science and Engineering, vol. 6, pgs. 636-638 (1986). In addition, numerous suitable elastomeric precursors are availablecommercially, examples including: DPX-546.00 which is produced by DEXCO (a jointventure between Dow Chemical and Exxon) which is a thermoplastic latex formulationcomprised of styrene-isoprene-styrene block copolymers; acrylic latex HYSTRETCH V-29available from the B.F. Goodrich Co.; silicone rubber LSR 590 which is a two part cross-linkable material available from Dow-Corning; and Q—THANE QW24 which is apolyurethane emulsion made by K.J. Quinn & Co. of Seabrook, New Hampshire.Further, the elastomeric precursor may comprise a latex having an elastomerwhich is made from block copolymers having the general formula A~B-A’ where A and A’are each a thermoplastic polymer endblock which contains a styrenic moiety such as apoly (vinyl arena) and where B is an elastomeric polymer midblock such as a conjugateddiene or a lower alkene polymer. The elastomeric precursor may be formed from, forexample, a latex formulation including (polystyrene/poly(ethylene-butylene)/polystyrene)block copolymers available from the Shell Chemical Company under the trademarkKRATON.The tie layer 27 may itself be tacky or, alternatively, a compatible tackifying resinmay be added to the precursor formulation to provide a tie layer 27 which providesimproved bonding between the elastomeric sheet 32 and the necked material 12. Inregard to the tackifying resins and tackified elastomeric compositions, note the resins andcompositions as described in U.S. Patent No. 4,789,699 issued to Keiffer et al., thedisclosure of which is hereby entirely incorporated by reference. Any tackifier resin canbe used which is compatible with the precursor, the neckable material and can withstandthe processing conditions (e.g. temperature). If blending materials such as, for example,polyolefins or extending oils are used, the tackifier resin should also be compatible withthose blending materials. REGALREZ and ARKON P series tackifiers are examples ofhydrogenated hydrocarbon resins. ZONATAK 501 is an example of a terpene17?101520253035CA 02265451 1999-03-09W0 98ll6678 PCTIUS97/18561hydrocarbon. REGALREZ hydrocarbon resins are available from Hercules Incorporated.ARKON P series resins are available from Arakawa Chemical (U.S.A.) Incorporated. Ofcourse, the present invention is not limited to use of the aforesaid tackifying resins, andother tackifying resins, which are compatible with the other components and canwithstand the processing conditions, can also be used.The elastic sheet brought into contact with the precursor or tie layer may be madefrom a wide variety of elastomeric materials, desirably from materials which allow theelastic material to be manufactured into sheet form. Suitable commercially availablematerials include, but are not limited to, a poIy(styrene/ethylene—butylene/styrene) blockcopolymer available from the Shell Chemical Co. under the trademark KRATON G;polyurethane elastomeric materials such as those available under the trademarkESTANE from B.F. Goodrich & Co.; polyamide elastomeric materials such as thoseavailable the trademark PEBAX from the Rislan Co.; and polyester elastomeric materialssuch as those available under the name HYTREL from E.l. DuPont De Nemours & Co.In addition, the elastic layer may be a multilayer material in that it may include two ormore individual coherent webs or films. Additionally, the elastic sheet, or one of thelayers in a multilayer elastic material, may contain a mixture of elastic and nonelasticfibers or particulates.Elastic sheets preferably have basis weights less than about 30 g/m2, forexample, from about 8.5 to about 25 g/m2. Such low basis weight sheets are useful foreconomic reasons, particularly for use in disposable products. However, depending onthe desired application of the elastic composite, elastic sheets having higher basisweights such as, for example, from about 30 to about 340 g/m2 may also be used.As indicated above with regard to the tie layer, tackifier may likewise be added tothe elastic sheet to improve its ability to adhere to the neckable material the tie layer.However, when significant tackifier is used within the elastic sheet it will often bedesirable to include an additional sheet of material, such as a second neckable material(or necked material depending on the point of engagement) prior to winding the elasticnecked-bonded laminate on a winder-roll in order to prevent the tacky elastic sheet fromadhering to the back of adjacent materials on the roll. Alternatively, dusting of the elasticsheet may also be used to prevent unwanted attachment from occurring when the elasticnecked-bonded composite material is wound in roll form.In a further aspect of the invention, an elastic necked-bonded composite isformed upon treating the elastomeric precursor 26 while in contact with both the neckedmaterial 13 and the elastic sheet 32. In reference to FIG. 4, there is schematically18?101520253035CA 02265451 1999-03-09W0 98/16678 PCTIUS97/18561illustrated an exemplary process for forming a composite elastic necked-bonded material62 by application of an elastomeric precursor 26 to a necked material 13. A neckedmaterial 13, an example being a reversibly necked material, is unwound from a supplyroll 14 and travels in the direction indicated by the arrows associated therewith as thesupply roll 14 rotates in the direction of the arrows associated therewith. An elastic sheet32 is simultaneously unwound from a second supply roll 34. Necked material 13 andelastic sheet 32 pass through nip 54 of the roll assembly 52. However, prior to enteringthe nip 54 of the roll assembly 52 an elastomeric precursor 26 is applied to the neckedmaterial 13 by coating assembly 24, such as a bank of spray heads. The coatingassembly may be positioned in relation to nip 54 such that the elastomeric precursor 26is applied to both the necked material 13 and the elastic sheet 32. The necked material13, elastic sheet 32 and elastomeric precursor 26 together, with the aid of guide roll 56,pass through the S-roll assembly 52 formed by the rolls 58 and 59.The S—roll assembly 52 may comprise a series of heated rolls 58 and 59 whichtreat the elastomeric precursor 26, e.g. dry or polymerize the precursor 26. Treating theprecursor 26 forms a polymeric tie layer which is directly bonded to the necked material13 as well as the elastic sheet 32, collectively the multiple layers comprise an elasticnecked-bonded laminate 62. One skilled in the art will appreciate that some formulationsmay require longer treatment times than provided by heated calender rolls 58 and 59and in such instances other conventional in—line heating techniques may be employedsuch as by additional heated rolls, infrared heaters, microwave heaters, heating lamps,ovens and other heating devices known in the art.As a further example, a bonder-roll arrangement (not shown) may be included inthe processing after treatment of the elastomeric precursor 26. The bonder-rollarrangement may comprise a smooth calender roll and a smooth anvil roll or may includea patterned calender roll, such as, for example, a pin embossing roll arranged with asmooth anvil roll as discussed herein above. Both the calender roll and the smooth anvilroll can be heated and the pressure between these two rolls adjusted by well knownmeans to provide a temperature sufficient to heat the tie layer and/or elastic sheet tocreate attachment. The necessary heat and/or pressure applied to attach the respectivelayers will vary with the selected materials. Typically, sufficient heat and pressure will bedirectly applied to heat one of the materials sufficiently above its T9 to cause it to soften.Conventional drive means and other conventional devices which may be utilizedin conjunction with the apparatus of Fig. 4 are well known and, for purposes of clarity,have not been illustrated in the schematic view of Fig. 4. in addition, it will be19?101520253035CA 02265451 1999-03-09W0 98/16678 PCTIUS97/18561appreciated by those skilled in the art that the particular process could be varied innumerous respects without departing from the spirit and scope of the invention. Forexample, the neckable material and elastic sheet can be formed by known extrusionprocesses, such as those discussed herein above, without first being stored on supplyrolls 14 and 34. Further, it will be appreciated that since the multiple layers are beingbrought into physical contact prior to treating the elastomeric precursor, the precursorcould be applied solely to either the necked material 13 or the elastic layer 32.In a further aspect of the invention, referring now to Fig. 5 of the drawings, thereis schematically illustrated an exemplary process for forming an elastic necked-bondedmaterial comprising multiple nonelastic neckable materials. A first and second neckablematerials 12A and 12B are unwound from supply rolls 14A and 14B. The first andsecond neckable materials 12A and 12B then travel in the direction indicated by thearrow associated therewith as the supply roll 14A and 14B rotates in the direction of thearrows associated therewith. The neckable materials may be formed by nonwovenextrusion processes, such as, for example, spunbonding or meltblowing processes, andfed directly into the present processing line without first being stored on a supply roll. it ISnoted that for the purposes of the present invention the first and second neckablematerials need not be identical or even similar materials. An elastic sheet 32 issimultaneously unwound from a supply roll 34 and travels in the direction indicated by thearrow associated therewith. The elastic sheet 32 is juxtaposed between the first andsecond neckable materials 12A and 12B as the materials are fed into nip 74 of rollassembly 72.Before the first and second neckable materials 12A and 12B come into contactwith the elastic sheet 32 or enter the nip 74 of the roll assembly 72, the neckablematerials 12A and 12B each pass under respective coating assemblies 24A and 24B. Astream of precursor 26A and 26B, directed from bank of spray heads traversing the widthof the neckable materials 12A and 12B, coat the side of the neckable materials 12A and12B that will face the elastic sheet 32. The elastomeric precursor 26A and 26B may beapplied just prior to nip 74, the point at which the juxtaposed neckable materials 12A and12B and elastic sheet 32 are brought into contact. This allows both neckable materials12A and 12B as well as both sides of the elastic sheet 32 to be coated with theelastomeric precursor 26. The precursor 26 may, however, alternatively be applied byother coating processes.The juxtaposed neckable materials 12A and 12B and elastic sheet 32 are guidedinto and through the drive-roll assembly 80. Because the peripheral linear speed of the20?101520253035CA 02265451 1999-03-09W0 98/ 16678 PCT/U S97/ 18561rolls of the S-roll assembly 90 is controlled to be higher than the drive-roll assembly 80,the contiguous materials are tensioned between the roll assemblies 80 and 90. Byadjusting the difference in the peripheral linear speed of the rolls, the multiple layers ofmaterial are tensioned and neck a desired amount, forming necked multi-layered material88. Additional roll assemblies can be added to the process if additional necking or multi-stage necking is desired. The respective components neck before entering the treatingdevice, however, the necked multi-layered material 88 may neck further upon heating.The necked materials 12A, 12B and elastic sheet 32 are maintained in such contiguoustensioned, necked condition while forming the tie layers.The multi-layered necked material 88 is heated by traveling through heated S-rollassembly 90 thereby forming tie layers, which are in intimate contact with the elasticsheet andthe respective necked materials. In the particular embodiment of FIG. 5, themulti-layered material 88 is heated while traveling about heated rolls 92 and 94 whichform stacked S-roll assembly 90 so that both sides of the fabric are heated. It isimportant to note that due to the ability of the precursor 26 to penetrate into the surfaceof neckable materials12A and 12B when applied, treatment of the precursor 26 forms atie layer which attaches to the to the necked material by bonding directly to the materialand/or mechanically attaching thereto by physically forming around fibers at or near thesurface of the neckable materials 12A and 12B. In addition, the heating provided bytreating apparatus 30 may also sufficiently heat the elastic sheet 32 to reset thethermoplastic elastic sheet 32 to the necked dimensions. Additional heating and/orbonding may be provided, such as by heated rolls 40 and 42 as desired. The elasticnecked bonded composite is then wound on wind-up roll 46.Conventional drive means and other conventional devices which may be utilizedin conjunction with the apparatus of Fig. 5 are well known and, for purposes of clarity,have not been illustrated in the schematic view of Fig. 5. In addition, as mentionedherein above, it will be appreciated by those skilled in the art that the particular processcould be varied in numerous respects without departing from the spirit and scope of theinvention. As an example, the precursor could be applied to the neckable layers 12A and128 by coating both sides of the elastic sheet 32 with the precursor 26. As an additionalexample, it is noted that some elastomeric precursors will, given sufficient time, react atroom temperature and thus with such formulations heating the contiguous necked layerscould be omitted. While wound on supply roll 46 the layers are kept in direct contact bythe pressure experienced on the rollallowing the precursor 26 to cure thereby forming anelastic necked-bonded laminate while on the roll 46.21?101520253035CA 02265451 1999-03-09W0 98/16673 PCT/US97/18561in a further aspect of the invention, referring to FIG. 6, an elastic necked-bondedmaterial may be formed by applying a molten elastomer over the elastic tie layer andnecked material. A neckable material 12 is unwound from a supply roll 14 and travels inthe direction indicated by the arrows associated therewith. The peripheral linear speed ofthe supply roll 14 is selected to be less than that of calender roll assembly 24, theneckable material is then tensioned a desired amount between the supply roll 14 anddriver roll assembly 24. The neckable material may be heated by a heating device 102while being necked. A precursor 26 is then printed on the necked material 13 by rollassembly 24. Just prior to entering nip 108, formed by rolls 112 and 114 of S-rollassembly 110, a molten elastomer 104 is extruded over the elastomeric precursor 26 andnecked material 13. For example, molten polyurethane at about 400 °F may be extrudedthrough one or more die tips 106 onto the precursor 26 forming an elastic sheet 32. Theheat from the molten elastomer104 acts to treat the precursor 26, e.g. dry a latex, andform tie layer 27. The second roll 114 of S-roll assembly 110 may be chilled in order tohelp rapidly cool the molten elastomer and thereby forming an elastic sheet 32 and theelastic necked-bonded laminate.Conventional drive means and other conventional devices which may be utilizedin connection with the apparatus of FIG. 6 are well known and, for the purpose of clarity,have not been illustrated in the schematic view of FIG. 6. in addition, as mentionedherein above, it will be appreciated by those skilled in the art that the particular processcould be varied in numerous respects without departing from the spirit and scope of theinvention. As an example, the elastomeric precursor could be applied prior to neckingthe neckable material 12 or during necking and prior to heating.EXAMPLE 1Spunbond material was pre-necked from 132 inches wide material to 52 incheswide, aging on the roll and handling of the roll allowed the material to equivalently relaxto 72 inches wide. An acrylic latex, HYCAR 26804 purchased from B.F. Goodrich, wasdiluted to about 35% by weight solids and the pH adjusted to about 8.5 with ammonia.The acrylic latex was sprayed over the necked spunbond material using a PAASHEAirbrush set VL—SET with a No. 5 needle and No. 5 head. The acrylic latex was sprayedthrough a pegboard having ‘/4 inch diameter holes in each 1 inch square cell. Thespunbond material had a basis weight of 45.08 g/m2 prior to application of the acryliclatex and a basis weight of 47.55 g/m2 after application of the latex and drying in an oven22?10CA 02265451 1999-03-09WO 98/16678 PCT/US97/18561for over 2 minutes at 108 °C. The spunbond material and applied acrylic latex werejuxtaposed with an elastic film of an elastic thermoplastic polyurethane, ESTANE 58661,purchased from B. F. Goodrich, and placed in a t-shirt press for 20 seconds at 130 °C.The resulting elastic necked bonded composite material had good adhesion between therespective layers and excellent elastic properties.While the invention has been described in detail with respect to specificembodiments thereof, it will be apparent to those skilled in the art that various alterations,modifications and other changes may be made to the invention without departing fromthe spirit and scope of the present invention. It is therefore intended that the claimscover all such modifications, alterations and other changes encompassed by theappended claims.23

Claims (39)

What is claimed is:

1. A method of forming a stretchable composite comprising:
applying a polymeric precursor to a first neckable material;
neck-stretching said neckable material to form a necked material; then treating said polymeric precursor to form a polymeric tie layer wherein said polymeric tie layer bonds to said necked material; and bonding an elastic sheet to said polymeric tie layer wherein said neckable material recovers when stretched in the necked direction.

2. A method according to claim 1 wherein said polymeric precursor is applied to said neckable material in a discontinuous pattern before neck-stretching said neckable material.

3. A method according to claim 2 wherein said polymeric precursor comprises a latex.

4. A method according to claim 3 wherein treating said polymeric precursor comprises drying said latex.

5. A method according to claim 2 wherein said polymeric layer comprises a thermoset polymer.

6. A method according to claim 5 wherein treating said polymeric precursor comprises heating.

7. A method according to claim 1 wherein said precursor is an elastomeric precursor and wherein said elastomeric precursor is applied to said neckable material before neck-stretching said neckable material.

8. A method according to claim 7 wherein said elastomeric precursor comprises a latex.

9. A method according to claim 8 wherein treating said elastomeric precursor comprises drying said latex.

10. A method according to claim 7 wherein said elastomeric layer comprises a thermoset polymer.

11. A method according to claim 10 wherein treating said elastomeric precursor comprises heating.

12. A method according to claim 11 further comprising the step of cooling said necked material in the necked condition wherein a reversibly necked material is formed from said neckable material.

13. A method according to claim 7 wherein said elastic layer is formed by applying a molten elastomer over said elastomeric precursor.

14. A method according to claim 7 wherein applying said elastomeric precursor comprises applying about 1 g/m2 to about 50 g/m2 of said elastomeric precursor to said neckable material.

15. A method according to claim 7 wherein applying said elastomeric precursor comprises applying less than about 20 g/m2 of said elastomeric precursor to saidneckable material.

16. A method according to claim 7 wherein said elastomeric precursor is treated and then the elastic sheet is brought into contact with said elastomeric tie layer and bonded thereto.

17. A method according to claim 7 wherein said elastic sheet is brought into contact with said elastomeric precursor before treating to form the elastomeric tie layer.

18. A method according to claim 1 wherein said polymeric precursor is applied to said neckable material after neck-stretching said neckable material.

19. A method according to claim 13 wherein said polymeric precursor comprises a latex.

20. A method according to claim 14 wherein treating said polymeric precursor comprises drying said latex.

21. A method according to claim 13 wherein said polymeric layer comprises a thermoset polymer.

22. A method according to claim 16 wherein treating said polymeric precursor comprises heating.

23. A method according to claim 1 wherein said polymeric precursor comprises an elastomeric precursor and wherein said elastomeric precursor is applied to said neckable material after neck-stretching said neckable material.

24. A method according to claim 23 wherein said elastomeric precursor comprises a latex.

25. A method according to claim 24 wherein treating said elastomeric precursor comprises drying said latex.

26. A method according to claim 23 wherein said elastomeric precursor comprises a thermoset polymer.

27. A method according to claim 26 wherein treating said elastomeric precursor comprises heating.

28. A method according to claim 27 further comprising the step of cooling said necked material in the necked condition wherein a reversibly necked material is formed from said neckable material.

29. A method according to claim 23 wherein said elastic layer is formed by applying a molten elastomer over said elastomeric precursor.

30. A method according to claim 23 wherein applying said elastomeric precursor comprises applying from about 1g/m2 to about 509/m2 of said elastomeric precursor to said neckable material.

31. A method according to claim 23 wherein applying said elastomeric precursor comprises applying less than about 20 g/m2 of said elastomeric precursor to saidneckable material.

32. A method according to claim 30 wherein said elastomeric precursor is treated and then the elastic sheet is brought into contact with said elastomeric tie layer and bonded thereto.

33. A method according to claim 30 wherein said elastic sheet is brought into contact with said elastomeric precursor before treating to form the elastomeric tie layer.

34. An elastic necked-bonded composite formed by the process of claim 1.

35. An elastic necked-bonded material comprising:
a porous necked material;
an elastic tie layer in intimate contact with said necked material wherein said elastic layer is mechanically attached to said necked material by surrounding portions of said porous material; and an elastic sheet bonded to said elastic tie layer.

36. The necked-bonded composite of claim 35 wherein said porous material is a nonwoven material.

37. The neck-bonded composite of claim 35 wherein said elastic layer comprises an elastic thermoset polymer.

38. The necked-bonded composite of claim 35 wherein said elastic tie layer comprises less than about 20g/m2.

39. The necked-bonded composite of claim 35 wherein said elastic tie layer comprises 1 g/m2 to about 50 g/m2.