COMPOSITE NONWOVEN WITH IMPROVED DIMENSIONAL RECOVERY

BACKGROUND OF THE INVENTION

(001 ) Elastic materials are widely used in various applications including waistband interlinings, medical wraps and bandages, and functional packaging materials. Elastic materials provide advantages over non-elastic products including conformability to body contours and movement, such as in waistband applications and medical wraps. Furthermore elastic materials provide therapeutic comfort when used as a medical wrap or bandage by applying constant pressure over an injured or wounded area. In medical wrap and bandage applications it is also desirable that the elastic materials be breathable to allow the transfer of oxygen to the wounded area and allow the escape of water vapor and other gases from the wounded area, in order to expedite healing, and be absorbent so blood and wound exudates can be removed from the wounded area by direct contact with the bandage. Absorbency is also desirable when the elastic materials are impregnated with topical ointments and other treatments, such as anesthetics, and subsequently used for therapeutic applications.

(002) In apparel applications such as waistband linings or embroidery backing it is advantageous that an elastic material be able to hold stitches, have high tensile strength and be compatible with repeated laundering and dry-cleaning processes without breaking down and losing its elastic properties. A further desirable feature of such products is that when stretched in MD direction they should exhibit no or only minimal decrease in length in the CD direction. This is desirable especially in apparel waistband applications, where some prior art materials when stretched have a tendency to decrease length in CD direction, distorting the waistband's appearance. Normally when a material is stretched in one direction, it tends to get thinner in the other two directions (characterized by the material's Poisson's Ratio). An elastic material with some or all of these properties is sought by those in the respective fields of apparel interlinings, medical wraps and bandages or functional wrapping fields. However, in practice it has been difficult to provide an elastic material having most or all of these desirable properties.

(003) For example due to the limitation of recoverable elastic stretch in nonwovens, the apparel industry has resorted to expensive solutions for waistband linings such as using woven fabrics cut on a 45-degree bias, or using knit fabrics, or

using webs composed of continuous elastomeric fibers, or using elastomeric films, or using various micro-webs, or employing complicated waistband designs with overlapping fabric segments allowing for slip. In medical wrap and bandage applications, attempts have also been made to incorporate recoverable elastic material properties with absorbency, breathability and strength.

(004) Another approach, besides the incorporation of elastomeric material layers or fibers to render nonwoven webs stretch recoverable, is to crepe or microcrepe the nonwoven. In creping, the nonwoven web is adhered to a creping surface and removed from the surface through the use of a doctor blade. In microcreping the stretch recoverable properties of the nonwoven web are obtained by a combination of retarding and compressing the web during its travel on and removal from a roll.

(005) Nevertheless, the various end-use markets continue to seek suitable nonwoven materials with recoverable stretch in combination with the other desired application properties at a cost effective price and simple production process.

DEFINITIONS

(006) Bicomponent fiber or filament - Conjugate fiber or filament that has been formed by extruding polymer sources from separate extruders and spun together to form a single fiber or filament. Typically, two separate polymers are extruded, although a bicomponent fiber or filament may encompass extrusion of the same polymeric material from separate extruders. The extruded polymers are arranged in substantially constantly positioned distinct zones across the cross-section of the bicomponent fibers or filaments and extend substantially continuously along the length of the bicomponent fibers or filaments. The configuration of bicomponent fibers or filaments can be symmetric (e.g., sheath:core or side:side) or they can be asymmetric (e.g., offset core within sheath; crescent moon configuration within a fiber having an overall round shape). The two polymer sources may be present in ratios of, for example (but not exclusively), 75/25, 50/50 or 25/75.

(007) Biconstituent fiber - A fiber that has been formed from a mixture of two or more polymers extruded from the same spinneret. Biconstituent fibers do not have the various polymer components arranged in relatively constantly positioned distinct

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 random. Biconstituent fibers are sometimes also referred to as multiconstituent fibers.

(008) Calendering - the process of pressing the surface of a nonwoven material between opposing surfaces. The opposing surfaces include flat platens and rollers. Either or both of the opposing surfaces may be heated. Either or both of the surfaces may include projections.

(009) Cellulose material - A material comprised substantially of cellulose. Cellulosic fibers come from manmade sources (for example, regenerated cellulose fibers or Lyocell fibers) or natural sources such as fibers or pulp from woody and non- woody plants. Woody plants include, for example, deciduous and coniferous trees. Non-woody plants include, for example, cotton, flax, esparto grass, sisal, abaca, milkweed, straw, jute, hemp, and bagasse.

(0010) Conjugate fiber or filament - A fiber or filament that has been formed by extruding polymer sources from separate extruders and spun together to form a single fiber or filament. A conjugate fiber encompasses the use of two or more separate polymers each supplied by a separate extruder. The extruded polymers are arranged in substantially constantly positioned distinct zones across the cross-section of the conjugate fiber or filament and extend substantially continuously along the length of the conjugate fiber or filament. The shape of the conjugate fiber or filament can be any shape that is convenient to the producer for the intended end use, e.g., round, trilobal, triangular, dog-boned, flat or hollow.

(001 1 ) Creping and microcreping - A process that compacts a nonwoven web in the machine direction such that a series of small, generally discontinuous parallel folds are imparted to the web. Microcreping differs from creping primarily in the size of the imparted folds.

(0012) Cross machine direction (CD) - The direction perpendicular to the machine direction.

(0013) Denier - A unit used to indicate the fineness of a filament given by the weight in grams for 9,000 meters of filament. A filament of 1 denier has a mass of 1 gram for 9,000 meters of length.

(0014) Drape - The ability of material to hang in loose or limp folds.

(0015) Elastic material - A material capable of stretching; particularly, capable of stretching so as to return to an original shape or size when force is released.

(0016) Fiber - A material form characterized by an extremely high ratio of length to diameter. As used herein, the terms fiber and filament are used interchangeably unless otherwise specifically indicated.

(0017) Filament - A substantially continuous fiber. As used herein, the terms fiber and filament are used interchangeably unless otherwise specifically indicated.

(0018) Hardwood pulps - Any fibrous materials of deciduous tree origin, which have been reduced to their component elements either through mechanical means, such as pulp grinders, or chemically by the use of various type of cooking liquors, usually under high temperature and pressure. Deciduous trees include, for example, alder, birch, eucalyptus, oak, poplar, sycamore, sweetgum and walnut.

(0019) Heat setting - A process employing heat and pressure on a substrate to accomplish certain desired results. On fabrics made of synthetic fiber (or of natural, chemically treated fibers), heat setting is used to prevent shrinkage or to impart a crease or pleat that will last through washings or dry cleanings.

(0020) Hydroentanglement - Hydroentanglement uses fine, high-pressure water jets to cause the nonwoven fibers to interlace. Hydroentanglement is sometimes known as spunlacing, as the arrangement of jets can give a wide variety of aesthetically pleasing effects. The water jet pressure used has a direct bearing on the strength of the web, but system design also plays a part. Nonwoven webs of different characteristics can be hydroentangled together to produce nonwoven composites with a gradation of properties difficult to achieve by other means.

(0021 ) Lyocell - Manmade cellulose material obtained by the direct dissolution of cellulose in an organic solvent without the formation of an intermediate compound and subsequent extrusion of the solution of cellulose and organic solvent into a coagulating bath.

(0022) Machine direction (MD) - The direction of travel of the forming surface onto which fibers or filaments are deposited during formation of a nonwoven web material.

(0023) Mechanical Bonding - In mechanical bonding the strengthening of the nonwoven web is achieved by inter-fiber friction as a result of the physical entanglement of the fibers. There are two types of mechanical bonding, hydraulic entanglement also known as hydroentanglement and needle punching.

(0024) Meltblown fiber - A fiber formed by extruding a molten thermoplastic material as filaments from a plurality of fine, usually circular, die capillaries into a high velocity gas (e.g., air) stream which attenuates the filaments of molten thermoplastic material to reduce their diameter. Thereafter, the meltblown fibers are carried by the high velocity gas stream and are deposited on a collecting surface to form a web of randomly dispersed meltblown fibers. Meltblown fibers are generally continuous. The meltblown process includes the meltspray process.

(0025) Natural fiber pulps - Any fibrous materials of non-woody plant origin, which have been reduced to their component elements either through mechanical means, such as pulp grinders, or chemically by the use of various type of cooking liquors, usually under high temperature and pressure. Non-woody plants include, for example, cotton, flax, esparto grass, sisal, abaca, milkweed, straw, jute, hemp, and bagasse.

(0026) Needle punching - In needle punching specially designed needles are pushed and pulled through the nonwoven web to entangle the fibers. The webs are usually pre-formed by carding, but can also include spunlaid and less frequently wetlaid webs. Needle punching can be used on most fiber types.

(0027) Non-thermoplastic polymer - Any polymer material that does not fall within the definition of thermoplastic polymer.

(0028) Nonwoven fabric, sheet or web - A material having a structure of individual fibers which are interlaid, but not in an identifiable manner as in a woven or knitted fabric. Nonwoven materials have been formed from many processes such as, for example, meltblowing, spunbonding, carding and wet laying processes. The basis weight of nonwoven fabrics is usually expressed in grams per square meter (gsm).

(0029) Polymer - A long chain of repeating, organic structural units including thermoplastic and non-thermoplastic polymers. Generally includes, for example, homopolymers, copolymers, such as for example, block, graft, random and alternating copolymers, terpolymers, etc, and blends and modifications thereof. Furthermore, unless otherwise specifically limited, the term "polymer" includes all possible geometrical configurations. These configurations include, for example, isotactic, syndiotactic and random symmetries.

(0030) Regenerated cellulose - Manmade cellulose obtained by chemical treatment of natural cellulose to form a soluble chemical derivative or intermediate compound and subsequent decomposition of the derivative to regenerate the cellulose. Regenerated cellulose includes spun rayon and regenerated cellulose processes include the viscose process, the cuprammonium process and saponification of cellulose acetate.

(0031 ) Softwood pulps - Any fibrous materials of coniferous tree origin, that have been reduced to their component elements either through mechanical means, such as pulp grinders, or chemically by the use of various type of cooking liquors, usually under high temperature and pressure. Coniferous trees include, for example, cedar, fir, hemlock, pine and spruce.

(0032) Spunbond filament - A filament formed by extruding molten thermoplastic materials from a plurality of fine, usually circular, capillaries of a spinneret. The diameter of the extruded filaments is then rapidly reduced as by, for example, eductive drawing and/or other well-known spunbonding mechanisms. Spunbond fibers can have deniers within the range of about 0.1 to 5 or more and extend substantially continuously from one end of a nonwoven web to the opposing end.

(0033) Spunbond nonwoven web - Webs formed (usually) in a single process by extruding at least one molten thermoplastic material as a plurality of filaments from a plurality of fine, usually circular, capillaries of a spinneret. The filaments are partly quenched and then drawn out to reduce fiber denier and increase molecular orientation within the fiber. The filaments are generally continuous and not tacky when they are deposited onto a collecting surface as a fibrous batt. The fibrous batt is then bonded by, for example, thermal bonding, chemical binders, mechanical needling, hydraulic entanglement or combinations thereof, to produce a nonwoven fabric.

(0034) Staple fiber - A fiber that has been formed at, or cut to, staple lengths of generally one quarter to eight inches (0.6 to 20 cm).

(0035) Substantially continuous - in reference to the polymeric filaments of a nonwoven web, it is meant that a majority of the filaments or fibers formed by extrusion through orifices remain as continuous unbroken filaments as they are drawn and then impacted on the collection device. Some filaments may be broken during the attenuation or drawing process, with a substantial majority of the filaments remaining intact over the length of the sheet.

(0036) Synthetic fiber - a fiber comprised of manmade material, for example glass, a polymer or combination of polymers, metal, carbon, regenerated cellulose and Lyocell.

(0037) Tex - A unit used to indicate the fineness of a filament given by the weight in grams for 1 ,000 meters of filament. A filament of 1 tex has a mass of 1 gram for 1 ,000 meters of length.

(0038) Thermoplastic polymer - A polymer that is fusible, softening when exposed to heat and returning generally to its unsoftened state when cooled to room temperature. Thermoplastic materials include, for example, polyvinyl chlorides, some polyesters, polyamides, polyfluorocarbons, polyolefins, some polyurethanes, polystyrenes, polyvinyl alcohol, copolymers of ethylene and at least one vinyl monomer (e.g., poly (ethylene vinyl acetates), and acrylic resins.

(0039) Web Bonding - Nonwoven webs, other than spunlaid, have little strength in their unbonded form and need to be consolidated by bonding. The three

basic types of bonding are thermal, chemical and mechanical. The choice of method is at least as important to ultimate functional properties as the type of fiber in the web.

SUMMARY OF THE INVENTION

(0040) This disclosure in one embodiment provides an elastic nonwoven composite material with recoverable elastic stretch that also exhibits high durability that is advantageous in apparel applications, specifically low to no shrinkage with regard to washing, drying and/or dry-cleaning. This disclosure in another embodiment provides an elastic nonwoven composite material with good absorbency, softness and breathable properties that can be used in medical and sports wrap, bandage and tape applications.

(0041 ) It has been discovered that microcreping a hydroentangled, nonwoven composite material, advantageously comprised of two or more nonwoven portions, in combination with heat setting, can achieve desirable properties of recoverable elastic stretch, in-use durability and still exhibit overall good absorbency, softness and breathability properties. In-use durability is characterized by full recovery after washing, dry-cleaning, repeated use or long time extension. It has been further discovered that by proper selection of binders the products can be advantageously rendered soft and comfortable such as for use in, for example, medical applications, or rendered durable and stiff such as for use in, for example, waistband lining applications.

(0042) In general, the compositions and steps of the disclosure may be alternately formulated to comprise, consist of, or consist essentially of, any appropriate components or processes herein disclosed. The compositions and steps may additionally, or alternatively, be formulated so as to be devoid, or substantially free, of any components, materials, ingredients, adjuvants, species or process used in the prior art compositions or that are otherwise not necessary to the achievement of the function and/or objectives of the present invention.

(0043) When the word "about" is used herein it is meant that the amount or condition it modifies can vary some beyond that disclosed so long as the advantages of the disclosure are realized.

(0044) A better understanding of the invention will be obtained from the following detailed description of the presently preferred, albeit illustrative, embodiments of the invention.

DETAILED DESCRIPTION

(0045) In one embodiment the elastic composite nonwoven material comprises a first wet-formed, nonwoven, fibrous portion applied to a second nonwoven, fibrous base substrate.

(0046) The second nonwoven base substrate is a pre-bonded web, which can for example, be a carded needlepoint web, a spunbond web or carded hydroentangled web (often termed as spunlace). The nonwoven base substrate can be in the basis weight range of about 15 to about 150 grams per square meter (g/m ² ), with the base substrate having an advantageous basis weight range of about 20 to about 90 g/m ² . The nonwoven base substrate is advantageously comprised of substantially continuous synthetic filament fibers such as in the case of spunbond nonwovens, or comprised of discrete, carded, staple fibers that have been mechanically bonded, such as with needlepunched or hydroentangled webs. The type of pre-bonding is not believed to be critical. For thermally bonded spunbond webs the degree of pre- bonding and type will vary, with a bond area as low as about 7 percent for a point bonded base substrate and up to 100 percent for a flat bonded base substrate. The preferred nonwoven base substrate is point bonded and generally has a bond area of about 10 to about 20 percent.

(0047) The second nonwoven base substrate fibers can be comprised of numerous commercially available materials. Advantageously, the base substrate fibers comprise polyesters, polyamides and polyolefins such as polyethylene and polypropylene, although other fiber materials such as rayon, cotton, polylactic acid, cellulose acetate and acrylics may also be employed.

(0048) The wet-formed, nonwoven, fibrous first portion comprises a mixture of synthetic short staple fibers, natural pulp or natural fibers and optionally other fillers and/or additives. The fillers and other additives can be combined with the fluid and fibers during formation of the dispersion to impart different desired properties to the resultant composite nonwoven. For example, where the end product is to be used in

the medical field, it may be desirable to incorporate fillers having a biologically beneficial property. Materials such as molecular sieves or similar compounds that provide sites for attracting and retaining biological components may be incorporated in this wet-formed nonwoven layer to assist in maintaining the sterile nature of the environment in which the nonwoven is used. Of course, it will be appreciated that the extent of fillers should be kept to an amount that does not too adversely impact the desired softness, drape and feel of the resultant end product.

(0049) The first nonwoven, fibrous portion is wet formed. This typically comprises the general steps of forming a fluid dispersion of the requisite fibers, pulp and other materials. The fluid dispersion is deposited on a foraminous member such as a fiber collecting wire. Fluid is withdrawn from the dispersion, typically through the foraminous member, to form a continuous sheet-like web material. The formed, wet formed web material may be further dried using known methods such as heated cans, ovens or heated air. Wet-formed nonwoven webs are preferred due to their intrinsically dimensionally stable properties and anisotropic characteristics. The first wet-formed, nonwoven, fibrous portion itself can be composed of multiple layers as commonly practiced in the field to render different functional properties to each sub-layer.

(0050) The wet-formed, nonwoven, fibrous first portion advantageously has a grammage in the range of about 20 to about 100 g/m ² , whereby the grammage of the end product, prior to drycreping is in the range of about 35 to about 250 g/m ² , preferably in the range of 35 - 160 g/ m ² . For apparel applications, the wet-formed, nonwoven first portion preferably contains about 10 to 100 percent natural pulp of either softwood or hardwood origin or combinations thereof, with the remaining fibers being synthetic fibers. Other applications can be envisioned where it is desirable to have 100% synthetic fibers to prevent staining issues in garments attributed to the presence of cellulose fibers. The preferred synthetic fibers are polyester, such as poly(ethylene terephthalate) ("PET"), from about 1 to about 6 denier, with about 1.5 denier preferred, with a fiber length in the range of about 0.25 to about 0.75 inch (about 6 to about 20 mm), with about 0.25 inch (about 6 mm) preferred. Other suitable synthetic fibers include, but are not limited to those of polyolefin origin such as polyethylene and polypropylene, polyamides, and rayon.

(0051 ) The natural pulp can be selected from substantially any class of pulp and blends thereof. Preferably the pulp is characterized by being entirely natural

cellulosic fibers and can include wood fibers as well as cotton, although softwood papermaking pulps, such as spruce, hemlock, cedar, and pine are preferred, in combination with hardwood papermaking pulps of which eucalyptus, are typically employed. Non-wood pulps, such as sisal, kenaf, abaca and others may also be used. The natural pulp may constitute up to about 75% of the finished product weight, accounting for the fiber, baseweb and binder components. The amount of natural pulp can vary substantially depending on the other components in the composite system and the end-use requirements, such as the ability to exhibit the desired barrier properties in the resultant composite nonwoven when used in medical bandage applications.

(0052) The first nonwoven, fibrous portion is applied directly to the second nonwoven base substrate. In one embodiment the materials of first nonwoven, fibrous portion are dispersed in fluid and the dispersion is applied over the second nonwoven base substrate. Fluid is withdrawn from the first nonwoven, fibrous portion to provide a wet, composite material. In another embodiment the first nonwoven, fibrous portion is deposited on a foraminous member such as a fiber collecting wire. Fluid is withdrawn from the dispersion, typically through the foraminous member, to form a continuous sheet-like web material. The formed, wet formed web material may be further dried using known methods such as heated cans, ovens or heated air to provide a preformed first nonwoven, fibrous portion. The preformed first nonwoven, fibrous portion is applied to the second nonwoven base substrate to provide a composite material.

(0053) After application of the first fibrous portion to the second base substrate the composite material is subjected to a low to medium pressure hydroentanglement operation of the type described in U.S. Pat. No. 5,009,747 issued to Viazmensky et al., the contents of which are hereby incorporated by reference. The hydroentanglement operation is achieved by passing the composite material under a series of fluid jets that directly impinge upon the top surface of the first wet-formed portion with sufficient force to cause the surface fibers to be propelled into, and entangle with, the second base substrate material. Preferably a series or a bank of jets is employed with the orifices and spacing between the orifices being substantially as indicated in the aforementioned patent. Hydroentanglement is the preferred method of combining the first portion and the second substrate as it provides the resulting nonwoven composite with a micro-pattern of parallel lines in the machine direction due the entanglement

jets. Once the hydroentangled composite has been micro-creped the hydroentanglement parallel lines in combination with the micro-creping pattern in the cross-machine direction result in a desirable linen pattern of small squares.

(0054) Once hydroentangled, the nonwoven composite material is dried in a conventional manner. After drying, the composite material is treated with a liquid binder to provide end-use stability, including tensile strength, washing resistance, or other desirable properties depending on its end-use application. Binder addition is accomplished by known methods such as size-press, curtain coater, spray coater or foam coater. Suitable binders include the chemical binders, also commonly known as liquid dispersion binders, such as the acrylics, vinyl acetates, polyesters, polyvinyl alcohols, and other traditional binder families. For example, in medical applications a small amount of a soft acrylic binder may be used to control linting or to act as a carrier for a particular color pigment or dye, or as a carrier for a wetting agent to further enhance the absorbency of the nonwoven composite. These soft binders are typically classified as having low glass transition temperatures, Tg, in the range of about -5 to about -35 degrees Celsius. Separately for apparel applications, the preferred binder chemistries are also acrylics, although those with a Tg in the range of about 0 to about 30 degrees Celsius and specifically designed to withstand the rigors of fabric washing, drying and dry-cleaning are used. The binder content is in the range of about 3 to about 35 weight percent of the overall final nonwoven composite material, with the middle of that range, such as 15 to 25%, being advantageous for apparel applications, with about 20% being preferred. The binder content is in the range of about 3 to about 35 weight percent of the overall final composite material, with an advantageous range of about 3 to about 10 weight percent for medical applications.

(0055) After the wet laid nonwoven sheet has been formed, optionally treated with binder and dried it is then conveyed to a microcreping process. The inventors believe that the exemplified microcreping process follows the general principles of microcreping, in particular the combination of retarding and compressing the wet laid nonwoven sheet during its travel on and removal from a roll to form a series of small, generally parallel folds in wet laid nonwoven web. The troughs and peaks of the folds generally extend in the cross machine direction, e.g. generally transversely to the machine direction. The nonwoven web is compacted in the range of 10 to 50 percent and preferably to a range of about 15 to about 45 percent. The grammage of the compacted web is preferably in the range of 40 - 290 g/m ² , more preferably in the

range of 40 - 185 g/m ² . The microcreping process provided by Micrex Corporation of Walpole Massachusetts under specification number C2715 has been found suitable. The microcreping machine has been discussed more in detail, for example, in US 3,260,778, although a similar drycreping action may be achieved by machines discussed, for example, in US patents 3,236,718, 3,810,280, 3,869,768, 3,975,806, 4,142,278, 4,859,169, and 4,894,196. Other alternative methods and apparatus suitable for carrying out the dry-creping have been discussed in US Patents 2,915,109 and 4,090,385.

(0056) The microcreping process is understood as a method where the drycreping is conducted with a bladed drycreper including a driven roll and a pressing surface for pressing a single or multilayer fibrous web against a driven roll sufficiently to cause the fiber web to be advanced forward, and opposing the advance of the web in the direction of the plane of the web with a retarder blade, a tip of which is held adjacent to the driven roll, at least one surface of the drycreper being heated to heat the thermoplastic fiber constituent to heat-set temperature of the thermoplastic fibers. In a preferred drycreping process the thermoplastic fibers include PET (polyester) fibers and the surface of the drycreper is heated to a temperature between 250F and 350F (139 ^Q C and 194 ^Q C). In other embodiments of process conditions, roll temperatures may be higher (e.g. to accomplish greater speed, and to drive off moisture to enable the fibers to reach heat set temperature more quickly) or lower (e.g. if the heat of friction provides additional heating of the fibers). The pressing surface and/or the driven roll are heated. The driven roll of the drycreper includes a continuous cylinder, the roll being equipped, if desired, with an internal heater. The internal heater includes heat exchange passages through which a hot fluid is passed. The hot fluid is hot water, steam, hot gas, hot air or combustion gas, or oil. In case the pressing surface is heated the heating mode may be any of the numerous known kinds, e.g. electric resistance, steam, hot water, hot gas or hot air. Radiant heat or flame pre-heating may also be employed. The dry-creping and simultaneous heat setting is conducted in a manner to shorten the web at least 10%, increasing bulk thickness of the sheet member. The dry-creping and simultaneous heat setting is conducted in a manner to shorten the web within the range between about 10 to 50%.

(0057) During compaction the web is heated to a temperature in the range of about 121 degrees Celsius (about 250 degrees Fahrenheit) to about 218 degrees

Celsius (about 425 degrees Fahrenheit), advantageously to a range of about 149 to

about 204 degrees Celsius (about 300 to about 400 degrees Fahrenheit), and more advantageously to a range of about 182 to about 193 degrees Celsius (360 to 380 degrees Fahrenheit), to eliminate shrinkage or expansion of the products when exposed to subsequent heating, especially in apparel applications where the products need to withstand process conditions of typically 163 degrees Celsius (325 degrees Fahrenheit) for 15 minutes for rendering fabrics wrinkle-free. The elevated temperatures during microcreping are also required to heat-set the microcreping pattern and to minimize the linting associated with the creping of wet-formed nonwovens and their discreet, discontinuous fibers. After the microcreping step, the nonwoven is cooled to room temperature. While visible, the creping pattern is fine enough that it does not alter the surface feel of the web after microcreping. However, the microcreping step improves the web's overall drape and introduces the recoverable machine direction stretch. The resultant microcreped, nonwoven elastic material exhibits substantially improved recoverable stretch properties, including ease of extension and low distortion. In particular the nonwoven when stretched up to 15% in MD direction exhibits no decrease in length in the CD direction.

(0058) Having generally described the invention, the following examples are included for purposes of illustration so that the invention may be more readily understood and are in no way intended to limit the scope of the invention unless otherwise specifically indicated.

EXAMPLES

(0059) Prototype composite webs were made and tested for suitability in various applications using combinations of the following ingredients.

• Northern bleached softwood kraft pulp, supplied by Marathon Pulp, Inc. located in Marathon, Ontario, Canada.

• Polyester (PET) resin labeled as F61 HC and supplied by Eastman Chemical Company, Inc. of Kingsport, Tennessee for the production of spunbond webs.

• Polyethylene synthetic pulp labeled as Fybrel SWP E-400 and manufactured by Mitsui Chemicals, Inc. headquartered in Tokyo, Japan.

• Aqueous acrylic emulsion binder, labeled as ECO E3988 with a Tg of +5 degrees Celsius, supplied by Rohm and Haas Company headquartered in Philadelphia, Pennsylvania.

(0060) The prototype samples were then tested using the following techniques.

• Basis weight was performed according to the TAPPI test procedure T410.

• Sample Thickness was measured according to TAPPI test procedure T41 1.

• Elmendorf Tear strength was measured according to TAPPI test procedure T414.

• Tensile strength and elongation at break testing were performed according to the TAPPI test procedure T494 using a Zwick Tensile Tester, model Z2.5. Grab Tensile testing used samples 4-inch wide by 6-inch in length, with a cross-head speed of 12-inch per minute; jaw span of 3-inch and constant rate of extension. Strip Tensile testing used samples 1 -inch wide by 12 inch long, with a cross-head speed of 1 -inch per minute; jaw span of 5-inch and a constant rate of extension.

(0061 ) Samples were washed in a typical laundry cycle and dried to establish their appearance, percent shrinkage and percent of recovery stretch performance.

The wash cycle was performed with a Whirlpool clothes washer model LFA 5700; normal wash cycle setting, using the medium (warm) water setting for a period of six minutes. Water temperature was measured as being about 42 degrees Celsius (about 108 degrees Fahrenheit). The wash was agitated at 58 strokes per minute followed by two spin cycles with a rinse cycle in between. The first spin cycle was at 340 rpm, and the final spin cycle was 515 rpm. The samples used for washing and drying were 1 1 - inches in machine direction length and 8.5-inches in cross machine direction length. The samples were washed in combination with two medium sized cotton laboratory coats used as ballast. Twenty milliliters of concentrated Tide fabric detergent were used during each washing cycle.

(0062) The drying of samples was performed in a Whirlpool clothes dryer model LAE 5700W0, using a heat setting of 85 degrees Celsius (185 degrees Fahrenheit), for 30 minutes. The samples were also dried in combination with two medium sized cotton laboratory coats used as ballast. Wash shrinkage was conducted after three separate wash and drying cycles. Samples were measured for machine direction length and cross machine direction length before and after the three cycles. Percent shrinkage was calculated as (initial length - final length)/ (initial length) x 100.

(0063) Cyclic tensile testing, using the Zwick Tensile Tester, model Z2.5, was conducted to establish the degree of recovery stretch. The samples were cut to 2-inch wide by 12 inch in length and conditioned according to TAPPI T494. The samples were mounted on 3-inch wide rubber faced jaws using a jaw span of 10-inches, and a cross-head speed of 10-inch per minute. The tensile tester was programmed to stretch the samples to different lengths, as noted, for ten cycles each elongation setting. For each of the ten cycles, the samples were extended to the predetermined level of their original length, held in extension for 15 seconds, and returned to its original position (0% elongation or 10-inches). After the tenth cycle the sample was removed from the jaws and measured for overall length. The percent stretch recovery was calculated as (initial length/ final length) ^* 100.

(0064) Percent of hot air shrinkage of samples was established by conditioning the samples to a temperature of 163 degrees Celsius (325 degrees Fahrenheit) for 15 minutes, using a Grieve & Henry convection oven, and measuring the length in the machine and cross machine direction before and after drying. The samples used for hot air drying were 1 1 -inches in machine direction length and 8.5-inches in cross machine direction length. Samples were hung in the machine direction attached by clips to a horizontal fixture located at a medium height of the oven interior. The percent shrinkage was calculated as (initial length - final length)/ (initial length) ^* 100. This test mimics typical temperature conditions used for processing wrinkle-free fabrics.

Example 1

(0065) This example shows the effect that microcreping, according to specification number C2715 process, has on product shrinkage and stretch recovery properties. Accordingly, a composite nonwoven was constructed by first forming two separate nonwoven webs and then hydroentangling them together to form a two-layer final product. The first web was prepared using an inclined wire paper making machine from a fiber furnish consisting of 100% Marathon softwood pulp to form a 30 grams per square centimeter (g/m ² ) wet-laid sheet. After formation, the wet-laid sheet was placed on top of a 20 grams per square centimeter (g/m ² ) PET web with 19% point bond area formed by the spunbond process. The two distinct webs, having a combined weight of 50 grams per square centimeter (g/m ² ), were then hydroentangled together at a process speed of 138 meters per minute, by passing them through eight

hydraulic manifolds in series, each manifold having a density of 2000 holes per lineal meter; each hole being 92 microns in diameter. The hydraulic pressure settings for each manifold were as follows: manifold one was set at 16 bar, manifold two was set at 24 bar, manifold three was set at 41 bar, manifold four was set at 50 bar, manifold five was set at 75 bar, manifolds six, seven and eight were set at 80 bar. The webs were conveyed through the hydroentanglement manifolds using a single layer PET fine mesh wire with a mesh count of 41 x 30.5/cm, a thickness of 0.33 mm and labeled as Flex 310K, supplied by Albany International. After hydroentanglement the composite web was treated with an acrylic binder, type ECO 3988 from Rohm & Haas, to achieve a binder content of about 17% of the overall final weight. The material was dried and accumulated after binder treatment. The overall material basis weight was 60 grams per square centimeter (g/m ² ) and labeled as sample A. Sample material B is sample A material after being processed through the Micrex ^® Corporation microcreping process to specification number C2715. Sample B was microcreped using a 25 percent compaction setting resulting in a fine ridge count of 16 to 18 per centimeter, at a speed of 23 meters per minute, and a heat setting temperature of 193 degrees Celsius. Sample C was microcreped to the same compaction and speed, but without the heat setting. Representative data for the composite nonwoven and its microcreped versions are summarized in the two tables below.

^* These samples expanded instead of shrinking after the three wash and drying cycles.

(0066) Table 1 demonstrates that superior shrinkage resistance is achieved by microcreping in combination with heat setting when compared to microcreping without heat setting and when compared to the sample without any microcreping.

(0067) Table 2 demonstrates that superior stretch recovery is achieved by microcreping with heat setting as sample B is able to maintain greater than 90% recovery for samples stretched up to 25%, whereas the sample without heat setting is only to able to retain greater than 90% recovery at less than 20% stretch. Sample A, without any microcreping is able to retain greater than 90% recovery at less than 25% stretch. The force data also illustrate that the ease of extension is better for sample B heat set during the microcreping process, as opposed to higher forces required to stretch the other two samples to a given elongation, without heat setting.

Example 2

(0068) A second prototype composite nonwoven composed of 100 percent synthetic fibers web was prepared by the same general method of example 1 except that the wet-laid top phase was composed of 100 percent Mitsui E400 polyethylene pulp and a weight of 30 grams per square centimeter (g/m ² ). The base phase was once again the 20 grams per square centimeter (g/m ² ) PET spunbond web. The hydroentanglement conditions deviated from example 1 , as only four manifolds were used, with the hydraulic pressures set as follows: manifold one was set at 55 bar, manifold two was set at 41 bar, manifold three was set at 48 bar, manifold four was set at 41 bar. Process speed was 20 meters per minute. The hydroentangled composite was treated with an acrylic binder, type ECO 3988 from Rohm & Haas, to achieve a binder content of about 17% of the overall final weight. The material was dried and accumulated after binder treatment. The overall material basis weight was 60 grams per square centimeter (g/m ² ). The hydroentangled composite was processed through the Micrex ^® Corporation microcreping process to specification number C2715 at a process speed of 8 meters per minute, at a compaction setting of 25 percent resulting in a fine ridge count of 16 to 18 per centimeter and a heat setting temperature of 132 degrees Celsius. Tables 3 and 4 illustrate typical properties for this composite material including its stretch recoverable performance.

Example 3

(0069) Another prototype was prepared as per example 2, with the following deviations. The top phase layer was a 20 grams per square meter (g/m ² ) wet-laid sheet composed of 100 percent Marathon softwood pulp and the base phase layer was a PET spunbond web of 80 grams per square meter weight (g/m ² ), resulting in a combined weight of 100 grams per square meter (g/m ² ) before hydroentanglement. The four hydraulic manifold pressures were set as follows: manifold one was set at 70 bar, manifold two was set at 48 bar, manifold three was set at 70 bar, manifold four was set at 34 bar. The hydroentangled composite was treated with 25% of its final weight with the ECO 3988 binder for a final weight of 136 grams per square meter (g/m ² ). The hydroentangled composite was processed through the Micrex ^® Corporation microcreping process to specification number C2715 at a process speed of 8 meters per minute, at a compaction setting of 35 percent resulting in a fine ridge count on the order of 22 per centimeter and a heat setting temperature of 200 degrees Celsius. Table 5 shows typical properties for this composite and Table 6 demonstrates the stretch recoverable properties with and without the microcreping process with heat setting.

(0070) Table 6 demonstrates that superior stretch recovery is achieved by microcreping with heat setting as the sample is able to maintain greater than 90% recovery for samples stretched up to 25%, whereas the sample without any microcreping is only able to retain greater than 90% recovery at less than 20% stretch.

The force data also illustrate that the ease of extension is better after the microcreping process, as opposed to the much higher forces required to stretch the sample without microcreping.

(0071 ) While preferred embodiments of the foregoing invention have been set forth for purposes of illustration, the foregoing description should not be deemed a limitation of the invention herein. Accordingly, various modifications, adaptations and alternatives may occur to one skilled in the art without departing from the spirit and scope of the present invention.