CA2209472A1 - Nonwoven laminate with cross directional stretch - Google Patents

Abstract

There is provided a nonwoven fabric laminate having cross-directional stretch properties. The laminate is comprised of at least three layers. The outer layers are spunbond nonwoven fiber webs which are made of crimped or crimpable fibers. The inner layer is an elastomeric polymer layer which may itself be composed of one or more thinner layers. The layers are preferably produced by sequentially depositing them onto a moving forming wire and bonding them together by a method excluding hydroentanglement to form the laminate.

Description

W O96/21562 PCTrUS96100428 NONWOVEN LAMINATE WITH CROSS DIRECTIONAL STRETCH
BACKGROUND OF THE INVENTION

This invention relates to the field of nonwoven fabrics for use in medical products, personal care products, garments and outdoor fabrics.
The manufacture of many products from nonwoven fabrics can be a very ~mplic~l~d affair involving many different cutting and joining steps. For example, the ,cr ,cess of making a surgical gown from nonwoven fabrics involves cutting holes 10 for the cleevcs and the head in a large piece of ma~r,al, cutting material for the cleevcs, and then joining the sleevcs, generally composed of two pieces, together with each other and the main body of the gown. Certain gowns have r~Worced areas (e.g. the elbows) for which addiliooal pieces must be cut, placed and joined.
There may be button holes or other manner of allac~""ent or closure required on 15 the amms, back or front of the gown. This manufacturing process requires pieces of fabric to be rotated, tumed upside down, folded, etc., many times.
One of the char~,le.i~lics of certain types of nonwoven fabrics which is useful in a variety of appl.~-tions is el~cticityl i.e. the ability to be stretched and then retum to approximately its original size. Such a characteristic is useful in, for 20 example, medical gowns, diapers, training pants, and adult incontinence products.
Stretchable nonwoven fabrics have been produced but have generally been limited to stretch in the machine direction (MD), i.e. the direction of production of the fabric. This is useful, but it has been found that many manufacturing processes would greatly benefit from nonwoven fabrics which could stretch in the cross-25 machine direction (CD). While a seemingly trivial issue, the requirement of repeatedly tuming the nonwoven fabric during the manufacturing process, of for example, a gown, can result in d~,.,aged fabric, increased maintenance costs and, of course, increased capital costs for the initial purchase of the manufacturing line equipment. Cross-machine stretchable nonwovens would simplify the 30 manufacturing process by eliminating a large number of rotating steps where the MD stretchable material must be tumed in order to give stretch in the desired direction.
Accordingly, it is an object of this invention to provide a nonwoven fabric laminate which is stretchable in at least the cross-machine direction.

W O96/21S62 PCTrUS96/00428 SUMMARY

The objects of the invention are provided by a multilayer laminate having cross-directional stretch in which the outer layers are crimped or crimpable spunbond polymer webs or fabrics which can be b-co",ponent fibers and at least one inner layer which is an elastomeric polymer layer. The layers are maintained in an unsl,~tched condition throughout their production and bonding into the laminate.

DETAILED ~ESCRIPTION
DEFINITIONS

As used herein the temm "nonwoven fabric or web" means a web having a structure of individual flbers or threads which are inle,'--d, but not in an ider,litia~'e or regularly repeating manner as in a knitted fabric. Nonwoven fabrics or webs have been formed from many processes such as for example, meltblowing processes, spunbonding processes, and bonded carded web processes. The basis weight of nonwoven fabrics is usually expressed in ounces of "lalenal per squareyard (osy) or grams per square meter (gsm) and the fiber .~ia,net~,a useful are usually expressed in l"icrons. (Note that to convert from osy to gsm, multiply osy by 33.91).
As used herein the term "r"icrotibers" means small diameter fibers having an average dia"leter not greater than about 50 microns, for example, having an average diameter of from about 0.5 microns to about 50 microns, or more particularly, micro~lbers may have an average diameter of from about 2 "li~,,uns to about 40 microns. The diameter of, for example, a polypropylene fiber given in microns, may be converted to denier by squaring, and multiplying the result by 0.00629, thus, a 15 micron polypropylene fiber has a denier of about 1.42 (152 x0.00629 = 1.415).
As used herein the term "spunbonded fibers" refers to small diameter fibers 30 which are formed by extruding molten themmoplastic material as fiiaments from a plurality of fine, usually circular capillaries of a spinnerette with the diameter of the extruded filaments then being rapidly reduced as by, for e~a"lr'e, in U.S. Patent no.
4,340,563 to Appel et al., and U.S. Patent no; 3,692,618 to Dorschner et al., U.S.

W O96/21562 PCTrUS96/00428 Patent no. 3,802,817 to Matsuki et al., U.S. Patent nos. 3,338,992 and 3,341,394 to Kinney, U.S. Patent no. 3,502,763 to Hartman, U.S. Patent 3,502,538 to Levy, and~ U.S. Patent no. 3,542,615 to Dobo et al. Spunbond fibers are generally r,ontinuous and larger than 7 microns, more particularly, often between about 10 and 30 m;clons.
As used herein the term "meltblown fibers" means fibers formed by extruding a molten the", lGplaslic material through a plurality of fine, usually circular, die capillaries as molten threads or r,la"~enls into a high velocity gas (e.g. air) strearn which attonuates the filaments of molten the"l~opl~sLic material to reducQ their10 diameter, which may be to ,nic,oriùer diameter. Thereafter, the meltblown flbers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of rando~ly disbursed meltblown fibers. Such a process is ~isclosed, for example, in U.S. Patent no. 3,849,241 to Butin. Mel' lo~n fibers are usuallymicrofibers which are generally smaller than 10 m;~,uns in c5ia,neter As used herein the term "polymer" generally includes but is not limited to, hol"opolymers, copolymers, such as for example, block, graft"dndo", and altemating copolymers, terpolymers, etc. and blends and "~odir,calions thereof.
Furthermore, unless otherwise speuirically limited, the term "polymer" shall include all possi~le geo",elrical configuration of the rnat~nal. These configurations include, but are not limited to isotactic, syndiotaclic, atactic and random symmetries.
As used herein, the term "machine direction" or"MD" means the length of a fabric as it is produced. The term "cross machine direction", "cross-direction" or "CD" means across the width of fabric, i.e. a direction generally perpendicular to the MD.
As used herein the term uico~ponent fibers" refers to fibers which have been formed from at least two polymers extruded from separate extruders but spuntogether to form one fiber. The polymers are arranged in subslanlially conslanlly pGsilioned distinct zones across the cross-section of the L.cD",ponenl fibers and extend continuously along the length of the bico")ponent fibers. The configuration of such a bicomponent fiber may be, for example, a sheath/core arrangement wherein one polymer is surrounded by another or may be a side by side arrangement or an "islands-in-the-sea" arrangement. r~ n"~onent fibers are taught in U.S. Patent 5,108,820 to Kaneko et al., U.S. Patent 5,336,552 to Strack et al., W O 96/21562 PCTrUS96/00428 and European Patent 0586924. For two co",ponent fibers, the polymers may be presenl in ratios of 75/25, 50150, 25n5 or any other desired ratios.
As used herein the term "biconstituent fibers" refers to fibers which have been formed from at least two polymers extruded from the same extruder as a blend. The term "blend" is defined below. Biconstituent fibers do not have the various polymer cornponents arranged in relatively conslar,lly posilioned distinct D
zones across the cross-sectional area of the fiber and the various polymers are usually not continuous along the entire length of the fiber, instead usually forming fibrils which start and end at lal1do"~. Biconstituent fibers are sor"eli",es also 10 referred to as mulliconsliluent fibers. Fibers of this general type are discussed in, for example, U.S. Patent 5,108,827 to Gessner. ''.~o."ponenl and ticonsliluent fibers are also discussed in the textbook Polvmer Blends and ComPosiles by John A. Manson and Leslie H. Sperling, copyright 1976 by Plenum Press, a di~/iSiOIl of Plenum Publishing Col,~lordlion of New York, IBSN ~306 30831-2, at pages 273 through 277.
As used herein the term "blend" means a mixture of two or more polymers while the term "alloy" means a sub-class of blends wherein the col"ponents are immiscible but have been col"paliL,ilized. "Miscibility" and "illll~iscibility" are defined as blends having negative and positive values, respectively, for the free energy of mixing. Further, "cG"~palibili~ation" is defined as the process of modifying theinlel racial properties of an immiscible polymer blend in order to make an alloy.
As used herein, the temms "necking" or "neck stretching" intercl)a"geably refer to a method of elongating a nonwoven fabric, generally in the machine direction, to reduce its width in a conl~.lled manner to a desired amount. The conl,~"ed stretching may take place under cool, room temperature or greater temperatures and is limited to an increase in overall dimension in the direction being stretched up to the elongalion required to break the fabric, which in most cases is about 1.2 to 1.4 times. When relaxed, the web retracts toward its original dimensions. Such a process is disclosed, for example, in U.S. Patent no. 4,443,513 to Meitner and Notheis and another in U.S. Patent no. 4,965,122 to Morman.
As used herein the temm "neck sorleni,1g" means neck sl,~tcl,ing carried out without the addition of heat to the material as it is sll eLched.

CA 02209472 l997-07-08 As used herein, the term "neckable ",dlenal" means any ",dlerial which can be necked.
As used herein, the term "necked ")al~rial refers to any material which has been consl,i-,led in at least one di-nension by processPs such as, for example, drawing or gathefing.
As used herein the temm "recove~' refers to a contraction of a stretched ",dl~rial upon t~""inalion of a biasing force r~ ..9 stretching of the ~..al~rial by arF~ic~tion of the biasing force. For example, if a llldlelial having a relaxed,unbiased length of one (1) inch was elongated 50 percent by sl.etcl-.' ~ to a length of one and one half (1.5) inches the ",al~,ial would have been elongated 50 percent and would have a stretched length that is 150 percent of its relaxed length. If this exemplary sl~etcl,ed material contracted, that is recovered to a length of one and one tenth (1.1) inches after release of the biasing and stretching force, the ",alarial would have recovered 80 percent (0.4 inch) of its elongation.
As used herein the term "un-necking" means a pr~cess applied to a reversibly necked material to extend it to at least its original, pre-necked d;.),ensions by the applica~ion of a slrelcl-ing force in a longitudinal or cross-machine direction which causes it to recover to within at least about 50 percent of its reversibly necked dimensions upon release of the stretching force.
As used herein, the temm "stitchbonded" means, for example, the stitching of a material such as in accordance with U.S. Patent 4,891,957 to Strack et al. or U.S.
Patent 4,631,933 to Carey, Jr.
As used herein, the term "medical product" means surgical gowns and drapes, face masks, head coverings, shoe coverings, wound dressings, bandages and s~e,;li~a~ion wraps.
As used herein, the term "personal care product" means diapers, baby bibs, training pants, absorbent underpants, adult incontinence products, wipers and feminine hygiene products.
As used herein, the term "~,,otecli~/e cove~' means a cover for vehicles such as cars, trucks, boats, airplanes, motorcycles, bicycles, golf ~ carts, etc., covers for equipment often left outdoors like grills, yard and garden equipment (lawnmowers, roto-tillers, etc.) and lawn fumiture, as well as ~loor coverings, table cloths and picnic area covers.

W O96/21562 PCTrUS96/00428 As used herein, the term "outdoor fabric" means a fabric which is primarily, though not exclusively, used outdoors. Outdoor fabric includes fabric used in protective covers, camper/trailer fabric, tarpaulins, awnings, canoFies, tents, agricultural fabrics (e.g. row covers) and outdoor apparel such as head coverings, industrial work wear and coveralls, pants, shirts, jackets, gloves, socks, shoe coverings, and the like.

TEST METHODS

l0 Melt Flow Rate: The melt flow rate (MFR) is a measure of the viscosity of a polymers. The MFR is expressed as the weight of material which flows from a capillary of known dimensions under a specified !oad or shear rate for a measured period of time and is measured in grams/10 minutes at 230~C according to, for example, ASTM test 1238, condilion E.
Grab Tensile test: The grab tensile test is a measure of breaking sl,~"yll, and elongalion or strain of a fabric when subjected to unidileclional stress between two clamps. Values for grab tensile strength and grab elongation are obtained using a specified width of fabric, clamp width and a consLant rate of extension. The sample is as wide as the clamps and longer than the distance between the clamps to give results representative of effective strength of fibers in the clamped width combined with addilional strength contributed by adjacent fibers in the fabric. This closely simulates fabric stress conditions in actual use. Results are expressed as pounds to break and percent stretch to break. Total energy can also be expressedas well as energy to break. Higher numbers indicate s~onger or more stretchable Z5 fabric.
Cyclic testing: In cyclic testing a male,ial is taken to a fixed extension or fixed load to develop a g,dphical representation of the results, with load on the y axis and elongation on the x axis. This graph yields a curve with an area thereunder called the Total Energy Absorbed or "TEA". The ratio of the TEA curves 30 for a sample for various cycles is a value independent of ",alel ial, basis weight and sample width that can be colllpal~d to other samples.

DETAILED DESCRIPTION

W O96/21562 PCTÇUS96/00428 The la",i"ale fabric of this invention com~,,ises a layered construction of at least one layer of an elastomeric thermoplastic polymer layer sandwiched betweenlayers of crimped fiber or filament spunbond nonwoven fabric. The spunbond fibers may be bico")ponent.
The elastomeric thermoplastic polymer layer useful in the p,d~lice of this invention may be those made from styrenic block copolymers, polyurethanes, polya",--~es, copolyesters, ethylene vinyl ~cel~tes (EVA) and the like and may be a meltblown web, a spunbond web, a film or a foam layer and may itself be con,posed o of one or more thinner layers of elastomeric the",~opl~clic polymer. Generally, any suitab'Q elastomeric fiber, film or foam forming resins or blends containing the same may be utilized to forrn the nonwoven webs of elastomeric fibers, elastomeric film or elastomeric foam.
Styrenic block copolymers include styrene/butadiene/styrene (SBS) block copolymers, styreneAsoprt:ne/styrene (SIS) block copolymers, styrene/ethylene-propylene/styrene (SEPS) block copolymers, styrene/ethylene-butadiene/styrene (SEBS) block copolymers. For example, useful elaslon,~nc fiber fG",)ing resins include block copolymers having the general formula A-B-A' or A-B, where A and A' are each a thermoplastic polymer endblock which contains a styrenic moiety such 20 as a poly (vinyl arene) and where B is an elastomeric polymer midblock such as a conjugated diene or a lower alkene polymer. Block copolymers of the A-B-A' type can have different or the same thermoplastic block polymers for the A and A' blocks, and the present block copolymers are intended to embrace linear, branched and radial block copolymers. In this regard, the radial block copolymers may be designated (A-B)m-X, wherein X is a polyfunclional atom or molec~'e and in whicheach (A-B)m- r~diates from X in a way that A is an endblock. In the radial blockcopolymer, X may be an organic or inorganic polyfunctional atom or m~lecl~'e and m is an integer having the same value as the functional group originally present in X.
It is usually at least 3, and is frequently 4 or 5, but not limited thereto. Thus, in the present invention, the expression "block copolymer", and particularly "A-B-A"' and ~ "A-B" block copolymer, is intended to embrace all block copolymers having such rubbery blocks and thermoplastic blocks as discussed above, which can be extruded (e.g., by meltblowing), and without limitation as to the number of blocks.

W O96/21S62 PCTrUS96/00428 U.S. Patent 4,663,220 to Wisneski et al. ~iscloses a web inciuding ~"i~,roriLers cGmprising at least about 10 weight percent of an A-B-A' block copolymer where "A" and "A"' are each a thermopl~stic endblock which cG.,.prises a styrenic moiety and where "B" is an elastomeric polytethylene-butylene) midblock, and from greater than 0 weight percent up to about 90 weight percent of a polyolefin which when blended with the A-B-A' block copolymer and subjected to an effective corr~:nalion of elevated temperature and elevated pressure con~lilions, is adapted to be extruded, in blended form with the A-B-A' block copolymer.
Polyolefins useful in Wisneski et al. may be polyethylene, polypropylene, polybutene, ethylene copolymers, propylene copolymers, butene copolymers, and mixtures thereof.
Commercial examples of such elaslo"~eric copolymers are, for e~cd""~'e, those known as KRATON~ materials which are available from Shell Chemical Company of Houston, Texas. KRATON~) block copolymers are available in several different formulations, a number of which are identified in U.S. Patent 4,663,220, hereby inc~",oraled by ,~ference. A particularly s~ 'le elaalo",enc layer may beformed from, for exa",r'e, elasl~",eric poly(styrene/ethylene-butylene/styrene) block copolymer available from the Shell Chemical Company of Houston, Texas under the trade designation KRATON~) G-1657.
Other exe" ,plary elastomeric materials which may be used to form an elastomeric layer include polyurethane elastomeric materials such as, for example, those available under the trademark ESTANE~ from B. F. Goodrich 8 Co., polyamide elasl~meric materials such as, for excl",r'e, those available under the trademark PEBAX~ from the Rilsan Company, and polyester elasl~"~eric materials such as, for example, those available under the trade desiynalioll HYTREL~ from E. I. DuPont De Nemours & Company.
FGIIIIatjOn of an elasl~",eric nonwoven web from polyester elastomeric materials is dis~osed in, for example, U.S. Patent No. 4,741,949 to Mo.",an et al., hereby incorporated by reference.
Elastomeric iayers may also be formed from elastomeric copolymers of ethylene and at least one vinyl monomer such as, for example, vinyl acetates, unsaturated aliphatic monocarboxylic acids, and esters of such monocarboxylic acids. The elaalo",elic copolymers and to""alion of elastomeric nonwoven webs W O96/21562 PCTAJS96~0428 from those elastomeric copolymers are disclosed in, for example, U.S. Patent No.4,803,117. Particularly useful elaslomeric meltblown U,e""op~lic webs are ~",posed of fibers of a ",ale,ial such as disrlosed in U.S. Patent 4,707,398 to Boggs, U.S. Patent 4,741,949 to Mo""an et al., and U.S. Patent 4,663,220 to Wisneski et al. In addition, the elaslol"elic meltblown thermopl~-slic polymer layer may itself be c6l"posed of one or more thinner layers of elaslon~enc meltblown the(",opl--slic polymer which have been sequentially deposile~ one atop the other or laminated togeU ,er by methods known to those skilled in the art.
The the""opl~,lic copolyester elastomers include copolyeUIere:slera having-10 the general formula:
O O O O

lS H-([O-G-O-~-C6H4-~]X-[O(CH2)~-O-~-C6H4-C]y)z~C~(CH2)bOH
where "G" is sele~t~d from the group consisling of poly(oxyethylene)-alpha,omega-diol, poly(oxypropylene)-alpha,omega-diol, poly(oxytel- dl "ell,ylene)-alpha,omega-diol and "a" and "b" are positive inleger~ including 2, 4 and 6, "x", "y", and "z" are positive integen including 1-20. Such male,ials generally have an elongaUon at break of from about 600 per~er,l to 750 pefcen~ when measured in accor~lance with ASTM D-638 and a melt point of from about 350~F to about 400~F (176 to 205~C) when measured in ac~ordance with ASTM D-2117. Co"""er ial examples of such copolyester materials are, for example, those known as ARNITEL~, formerly available from Akzo Plaslics of Amhem, Holland and now available from DSM of Sittard, l lc"- ld, or those known as HYTREL~ which are available from E.l.
duPont de Nemours of Wilmington, Delaware.
Exar"pl~s of suitable foams include those produced by the General Foam Coi,uoralion of Paramus, New Jersey. Such foams are polyurethane foams under the trade designation ~4000 Series". Such foams are described in U.S. Patent 4,761,324 to Rautenberg et al. at column 6, lines 53~8, hereby i"cG"~oraled by ~fer~l-ce.
An elas~o",eric meltblown layer may be slil~hbonded in acco,dance with U.S. Patent no. 4,891,957 to Strack et al. Stil~hbor,ding imparts strength and durability to the slilcl,bonded product and sli~chbond;ng in the present invention is believed to impart increased abrasion resislance to the laminate. While stitchbonding generally is used to join two or more materials together, in this _ W O96121562 PCTrUS96/00428 embodiment of the present invention the elas~o."enc meltblown layer is slilcl)bonded alone and then used in the fabrication of the la",i"ale.
The spunbond nonwoven fabric is produced by a method known in the art and described in a number of the references cited above. Briefly the spunbond process generally uses a hopperwhich s~pl.es polymer to a heated extruder. The extruder supplies melted polymer to a spinnerette where the polymer is fiberized as it passes through fine open- ~gs usually arranged in one or more rows in the s~:.,neretla, forming a curtain of rila",er.~. The r~id,-,~nLs are usually quenched with air at a low pressure drawn usually pneumatically and dPI~osi~ed on a moving 10 rord",i"ous mat, belt or"forming wire" to form the nonwoven fabric.
The fibers produced in the spunbond process are usually in the range of from about 10 to about 30 ",icrons in clia",eter depending on process condilions and the desired end use for the fabrics to be produced from such fibers. For example increasing the polymer mlole~ weight or decreasing the processing lell,perdlure result in larger cliameter fibers. Changes in the quench fluid temperature and pneumatic draw pressure can also affect fiber diameter.
Polymers useful in the spunbond process generally have a process melt temperature of between about 350~F to about 610~F (175~C to 320~C) and a melt flow rate as defined above, in the range of about 10 to about 150 more particularly between about 10 and 50. Examples of suitable polymers include polypropylenes polyethylenes and polyamides.
Bicomponent fibers may also be used in the prd~ lice of this invention.
Bico",ponent fibers are co""nonly polypropylene and polyethylene arranged in a sheath/core "islands in the sea" or side by side configuration. Suitable commercially available materials include polypropylene designated PP-3445 from the Exxon Chemical Company of Baytown Texas ASPUNtl~) 6811A and 2553 linear low density polyethylene from the Dow Chemical Company of Midland Michigan 25355 and 12350 high density polyethylene from the Dow Chemical Company DURAFLEX~ DP 8510 polybutylene available from the Shell Chemical Company of Houston Texas and ENATHENE~) 720-009 ethylene n-butyl acrylate from the Quantum Chemical Corporation of Cincinnati Ohio.
Certain biconstituent fibers may also be used in the practice of this invention.Blends of a polypropylene copolymer and polybutylene copolymer in a 90/10 W O 96/21562 PCTrUS96100428 mixture have been found effective. Any other blend would be effective as well provided they may be spun and provide crimped or cri",pable fibers.
The fibers of the spunbond layer used in the pra- lice of this invention must be crimped or cti""~able since the inventors have found that cnmped fiber webs when laminated to an elasLo",eric meltblown layer have enough "give" to stretch to a larger dimension without breaking.
The crimping of a spunbond fiber may be aceo,nplished through a number of methods. One ",ell.od is to produce a spunbond web onto a forming wire and then pass the web between two dnums or rollers with dirrenng surfaces. The rollers bend the fibers of the web as it passes therebetween and produces the desired crimp.
Another method of creating fiber crimp is to mechanically stretch each fiber.
When Lico.l.ponent spunbond fibers are used in the praclice of this invention crimping may be accGinplished by heating the fibers. The two polymers making up the bi~mponent fibers may be selected to have different coerri~ ents of expansion and so upon heating create crimps in the fibers. This heating may be done after the formation of the web on the fG,---ing wire at a ~emperal.lre of from about 110~F (43~C) up to a temperature less than the melting point of the lower melting co",porlent of the fibers. This heating may altematively be done as the fibers drop from the spinnerette to the forming wire as taught in European patent applicalio,) 586 924 to Pike et al. which was published on March 16 1994. In thePike process heated air in the range of from about 11 0~F (43~C) up to a temperature less than the melting point of the lower melting component of the fibers is directed at the fibers as they fall causing the two polymers to expand differentially to one another and the fiber to crimp.
The laminated fabric of this invention may be made by first depositing onto a forming wire a layer of crimped spunbond fibers. A layer of elaslo",eric meltblown fibers is deposiled on top of the c,imped spunbond fibers. Lastly anotl,er layer of crimped spunbond fibers is deposited atop the meltblown layer and this layer is usually pre~o"ned. There may be more than one layer of elastomeric meltblown fibers. None of the layers are stretched in any direction during the production process of the laminate including the bonding step.
Altematively all of the layers may be produced independently and brought together in a separate lamination step. If this method of manufacture is chosen it W O96/21562 PCTrUS96/00428 remains important that the layers not be sl,etched during the making of the lan ,inate.
The requi~e",ent of the fabric being u"sl,e:tched during fab,i~lion into a la",;nate means that the fabric is not su~ject~d to any adJilional or Pxcessive stretching force beyond that no""ally provided by the type of n,echanis,n that is usually used to produce the laminate i.e. rollers and winders which move the fabric along the path of the process from pre- to post- lamination. The fabric of this invention does not need to be neck-sl(elched neck softened or un-necked to provide the desired stretch properties.
After the addition of the last layer of crimped spunbond fibers the layers are bonded to produce the laminate. The bonding may be done thermally such as by through-air bonding or by point bonding using pdlla" ,ed calender rolls.
Through-air bonding or"TAB" is ~isc-lssed in Eu,opean patent a~F'~otion 586 924 to Pike et al. and is a process of bonding a nonwoven b.A~mponenl fiber web which is wound at least partially around a perforated roller which is enclosed in a hood. Air which is surfi~ ie"ll~ hot to melt one of the polymers of which the fibers of the web are made is forced from the hood through the web and into the pe,rordled roller. The air velocity is between 100 and 500 feet per minute and the dwell time may be as long as 6 seconds. The melting and resolidifi~lion of the polymer provides the bonding. Since TAB requires the melting of at least one component to ac~" ,p' sh bonding it is restricted to b ~ A mponenL fiber webs.
Themmal point bonding using calender rolls with various patterns have been dcveloped. One example is the expanded Hansen Pennings pattem with about a 15% bond area with about 100 bonds/square inch as taught in U.S. Patent 3 855 046 to Hansen and F'annings. Another co""non pattem is a did",ond pattem with repeating and slightly offset dia,nonds.
The bonding of the laminate may alle("ali~/ely be done ull,dsonically, by print adhesive bonding by any other method known in the art to be effective except themethod of hydroentanglement.
The fabric of this invention may be treated either the individual layers prior to la"~i"alion or the entire fabric after lamination with various chemicals in accordance with known techniques to give properties for specialized uses. Such treatments include water repellant chemicals sofLening chemicals fire ~etardant W O 96/21S62 . PCTrUS96rW~28 chemicals oil repellant che,n~ 's anlisl~lic agents and mixtures thereof. PisJ",enLs may also be added to the fabric as a post-bonding treatment or allt:llldli./ely added to the polymer of the desired layer prior to fiberi~alion.
It has been found that the fabric of this invention stretches in the cross-machine direction by at least about 100 percent.
The fabric of this invention may be used in personal care products medicalproducts and outdoor fabrics. It is also believed this fabric would be useful in automotive aFFI .. ~ns such as car headliners.
The properties of various laminates were co",pa,~d. These laminates are described below where the Samples are laminates made in accGrdance with this invention and the Control is not.

Control Spunbond polypropylene fibers in both outer facing layers with an elastomeric meltblown layer in between.
The elastomeric meltblown was made from Shell's KRATON~ G-2740 and had a basis weight of appro~i",aLely 1.8 osy (61 gsm).
The spunbond fiber was Exxon PD-3445 polypropylene extnuded through 2') 0.6mm holes at a rate of 0.7 gramslhole/minute (ghm) having a basis weight of 0.7 osy (22 gsm) for each facing layer. The fabric was bonded at a temperature of 291~F using thermal calender bonding with a 5% spiral pattem. None of the layerswas stretched during production or bonding.

SamPIe 1 Spunbond fibers in both outer facing layers with an elasLomeric meltblown layer in between.
The elaslG",eric meltblown was made from Shell's KRATON~ G-2740 and had a basis weight of appr-,xi",ately 1.8 osy (61 gsm).
The spunbond fabric was produced from a spin pack having altemate rows of fibers to produce a mixture of different types of fibers in one layer of fabric or web resulting in a c ~i",pable web. One row of fibers was Exxon PD-3445 polypropylene W O96/21562 PCTrUS96/00428 and the next row was a blend of 90 weight percent of a Shell polypropylene copolymer and 10 weight percent Shell Duraflex~19 polybutylene copolymer. The polypropylene copolymer had an ethylene content of 3.2 weight percent and the polybutylene copolymer had an ethylene con~ent of 6 weight percent. All polymerswere extruded through 0.6mm holes at a rate of 0.5 grams/hole/minute (ghm) and having a basis weight of 1.0 osy (34 gsm) for each facing layer. The fabric was bonded at a te",peraLure of 291~F using ll,e",)al calender bonding with a 5% spiral pattem. None of the layers was sl-etched during production or bonding.

SamPIe 2 Biconstituent spunbond fibers in both outer facing layers with an elastor"eric meltblown layer in between.
The elaslo",eric meltblown was made from Shell s KRATON~) G-2740 and had a basis weight of approximately 1.8 osy (61 gsm).
The spunbond was a biconstituent blend of 90 weight percent polypropylene copolymer and 10 weight percent polybutylene copolymer as described in Sample 1 extruded through 0.6mm holes at a rate of 0.7 grams/hole/minute (ghm) and havinga basis weight of 1.0 osy (34 gsm) for each facing layer to provide a crimpable web.
The fabric was bonded at a temperature of 270~F using thermal calender bonding with a 5% bonding area square pattem. None of the layers was sl,et~ hed during production or bonding.

SamPIe 3 Biconslil.Jent spunbond fibers in both outer facing layers with an elastomeric meltblown layer in between.
The elastomeric meltblown was made from Shells KRATON~ G-2740 and had a basis weight of approximately 1.8 osy (61 gsm).
The spunbond was a biconsliluent blend of 90 weight percent polypropylene copolymer and 10 weight percent polybutylene copolymer as described in Sample 1 extruded through 0.6mm holes at a rate of 0.53 grams/hole/minute (ghm) and having a basis weight of 0.7 osy (24 gsm) for each facing layer to provide a W O 96/21562 PCTrUS96100428 c~ F~t'~ fiber. The fabric was bonded at a temperature of 291~F using thermal calender bonding with a 5% bondi"g area square pattem. None of the layers was stretched during production or bonding.

SamDIe 4 r Crimped bicomponent spunbond fibers in both outer facing layers with an elaslol "~rlc meltblown layer in between.
The elastomeric meltblown was made from Shell's KRATON~) G-2740 and ~~ had a basis weight of approximately 1.8 osy (61 gsm).
The crimped spunbond was a side-by-side fiber of Exxon PD-3445 polypropylene and Dow Aspun~ 6811A polyethylene extruded through 0.6mm holes at a rate of 0.65 grams/hole/minute (ghm) and having a basis weight of 0.8 osy (27 gsm) for each facing layer. The fabric was bonded at a temperature of 258~F using through-air bonding. None of the layers was stretched during production or bonding.

Sample 5 Crimped ~is-n,ponent spunbond fibers in both outer facing layers with an elastomeric meltblown layer in between.
The elaslumeric meltblown was made from Shell's KRATON~ G-2740 and had a basis weight of approximately 1.8 osy (61 gsm).
The crimped spunbond was a side-by-side fiber of Exxon PD-3445 polypropylene and Dow Aspun~ 6811A polyethylene extruded through 0.6mm holes at a rate of 0.65 grams/hole/minute (ghm) having a basis weight of 0.4 osy (13 gsm) for each facing layer. The fabric was bonded at a temperature of 258~F using through-air bonding. None of the layers was stretched during production or bonding.
The above described lalll )ales were s~ je~ted to tests for cross-machine direction stretch and recovery preformed on a Instron Sintech machine. A three inch wide sample was used and the sl,etching speed was 300 mm/min for peak load and peak strain. Peak elongation or strain is expressed in percent. Peak load W O96/21562 PCTrUS96/00428 is expressed in grams. Cycle testing elongation is expressed in percent. First cycle load at cycle elongalion (A) is expressed in grams. The properties of the Samples are shown below in Table 1.

Table 1 Peak Peak Cycle Strain Load Elong. A
Control 79 3690 50 2690 Sample 1 130 3682 80 3720 Sample 2 190 1420 125 1210 Sample 3 125 2980 75 2230 Sample 4 101 2970 55 2290 Sample 5 25 1060 50 1420 The inventors believe that the data for crimped ~.cD~pol-en~ fibers (Samples 4 and 5) would be improved with a dirrerenl bond method though the cyclic testing data is favorable. The method used through-air bonding provides many bond spots and probably results in loss of stretchability therefore through-air bonding is not prefe"ed.
The other Samples and the Control did not use through-air bonding.
The data indica~es that the fabric of this invention provides exce"~nt cross-machine direction stretch at lower loads than for u"~i",pa~ e polypropylene spunbond.
This is a very useful prope,l~ which si",plifies the manufacture of many products such as diapers and surgical gowns, from which this fabric is made.

Claims (20)

What is claimed is:

1. A laminate having cross-directional stretch comprising:
a first layer of a crimpable spunbond polymer web;
a second layer of an elastomeric polymer;
a third layer of a crimpable spunbond polymer web;
wherein said layers are bonded together by a method excluding hydroentanglement to form a laminate and wherein said layers are maintained in an unstreched condition throughout their production and bonding into said laminate.

2. The laminate of claim 1 wherein each spunbond layer may independently be selected from the group consisting of crimpable bicomponent fibers, crimpable biconstituent fibers and crimpable mixtures of different types of fibers.

3. The laminate of claim 1 wherein said layers are bonded to each other in an unstretched condition by the method selected from the group consisting of thermal bonding, ultrasonic bonding print bonding and adhesive bonding.

4. The laminate of claim 1 wherein said elastomeric polymer layer is selected from the group consisting of elastomeric meltblown webs elastomeric spunbond webs elastomeric films and elastomeric foams.

5. The laminate of claim 4 wherein said elastomeric polymer layer is comprised of one or more thinner layers.

6. The laminate of claim 4 wherein said elastomeric layer is stichbonded prior to incorporation into said laminate.

7. The laminate of claim 4 wherein said elastomeric layer comprises at least about 10 weight percent of an A-B-A' block copolymer where "A" and "A"' are each a thermoplastic endblock which comprises a styrenic moiety and where "B" is an elastomeric poly(ethylene-butylene) midblock and snd where "B" is an elastomeric poly(ethylene-butylene) midblock, and from greater than 0 weight percent up to about 90 weight percent of a polyolefin which when blended with the A-B-A' block copolymer and subjected to an effective combination of elevated temperature and elevated pressure conditions, is adapted to be extruded, in blended form with the A-B-A' block copolymer.

8. The laminate of claim 4 wherein said elaslomeric polymer layer polymer is selected from the group consisting of styrenic block copolymers, polyurethanes, polyamides, copolyesters, copolyetheresters and ethylene vinyl acetated.

9. The laminate of claim 5 wherein said polymer is a mixture of an A-B-A' block copolymer and polypropylene.

10. The laminate of claim 5 wherein said elastomeric polymer layer comprises elastic fibers of a block copolymer.

11. The laminate of claim 10 wherein said polyeetherester has the general formula:

where "G" is selected from the group consisting of poly(oxyethylene)-alpha, omega-diol,poly(oxypropylene)-alpha,omega-diol, poly(oxytetramethylene)-alpha,omega-diol and "a" and "b" are positive inlegers selected from the group consisling of 2, 4 and 6 and "x", "y" and "z" are positive integers selected from the group consisting of numbers between 1 and 20.

12. The laminate of claim 1 wherein at least one layer has been treated with a chemical selected from the group consisting of water repellant chemicals, softening chemical, fire retardant chemicals, oil repellant chemicals and mixtures thereof.

13. The laminate of claim 1 wherein said crimpable spunbond fibers webs are comprised of bicomponent fibers in a sheath/core arrangement with polypropylene as the core and polyethylene as the sheath.

14. The laminate of claim 1 wherein said layers have basis weights between about 0.25 and 3 osy.

15. The laminate of claim 1 which is present in a product selected from the group consisting of medical products personal care products and outdoor fabrics.

16. The laminate of claim 15 wherein said product is a personal care product and said personal care product is a diaper.

17. The laminate of claim 15 wherein said product is a personal care product and said personal care product is a feminine hygiene product.

18. The laminate of claim 15 wherein said product is a medical product and said medical product is a surgical gown.

19. The laminate of claim 15 wherein said product is a medical product and said medical product is a face mask.

20. The laminate of claim 15 wherein said product is a medical product and said medical product is a wiper.