Patent ID: 12234583

DETAILED DESCRIPTION

The present invention is directed to improved techniques for hydraulically treating and imparting apertures to nonwoven fabrics and to nonwoven fabrics made using these methods.

A nonwoven web hydraulically treated and/or formed with an aperture pattern, in accordance with the present invention may be suitable for use in disposable absorbent articles. As used herein, the term “absorbent article” refers to articles which absorb and contain fluids and solid materials. For example, absorbent articles may be placed against or in proximity to the body to absorb and contain the various exudates discharged by the body. Absorbent articles may be articles that are worn, such as baby diapers, adult incontinence products, and feminine care products, or hygienic products that are used to absorb fluids and solid materials, such as for the medical profession which uses products like disposable gowns and chucks. In particular, nonwovens in accordance with exemplary embodiments of the present invention may be used as or as part of a body contacting layer of an absorbent article, such as a topsheet, or used to form other components of absorbent articles, such as, for example, a backsheet, waist belt, or fastening tabs. The nonwovens in accordance with exemplary embodiments of the present invention may also be used for packaging or wrapping items such as absorbent articles. The term “disposable” is used herein to describe absorbent articles which are not intended to be laundered or otherwise restored or reused as an absorbent article, but instead are intended to be discarded after a single use and, preferably, to be recycled, composted or otherwise disposed of in an environmentally compatible manner.

The term “batt” is used herein to refer to fiber materials prior to being bonded to each other. A “batt” comprises individual fibers, which are usually unbonded to each other, although a certain amount of pre-bonding between fibers may be performed, and this pre-bonding may occur during or shortly after the lay-down of fibres in a spun-melt process, for example. This pre-bonding, however, still permits a substantial number of the fibers to be freely movable such that they can be repositioned. A “batt” may comprise several layers, resulting by depositing fibers from several spinning heads in a spunmelt process, and distributions of a fiber diameter thickness and a porosity in the “sub layers” laid-down from individual heads do not differ significantly. Adjacent layers of fibers need not be separated from each other by a sharp transition, and individual layers may blend partly in the area around the boundary.

The terms “fibers” and “filaments” are used interchangeably in this application unless otherwise specified (such as “endless filaments” or “short fibers” etc).

The terms “nonwoven, nonwoven fabric, sheet or web” as used herein refer to a manufactured sheet or web of directionally or randomly oriented fibers or filaments which are first formed into a batt and then one or more batts are laid one on each other and consolidated and bonded together by friction, cohesion, adhesion or one or more patterns of bonds and bonding impressions created through localized compression and/or application of pressure, heat, ultrasonic, or heating energy, or a combination thereof. The term does not include fabrics which are woven, knitted, or stitch-bonded with yarns or filaments. The fibers may be of natural or man-made origin and may be staple or continuous filaments or be formed in situ. Commercially available fibers have diameters ranging from about 0.0005 mm to about 0.25 mm and they come in several different forms: short fibres (known as staple, or chopped), continuous single fibres (filaments or monofilaments), untwisted bundles of continuous filaments (tow), and twisted bundles of continuous filaments (yarn). Nonwoven fabrics can be formed by many processes including but not limited to melt-blowing, spun-bonding, spun-melting, solvent spinning, electro-spinning, carding, film fibrillation, melt-film fibrillation, air-laying, dry-laying, wet-laying with staple fibres and combinations of these processes as known in the art. The basis weight of nonwoven fabrics is usually expressed in grams per square meter (gsm).

The term “spunmelt fibers” refers to fibers formed by heating thermoplastic polymers (e.g., polypropylene, polyester or nylon) and extruding them through a metal plate with hundreds of holes in it, known as a spinneret or die. Examples of spunmelt fibers include spunbond fibers and meltblown fibers. Spunmelt fibers might be monocomponent in that they are formed of a single polymer component or a single blend of polymer components or multicomponent where the cross-section of each fiber comprises at least two discrete polymer components or blends of polymer components, or at least one discrete polymer component and at least one discrete blend of polymer components. Fibers with two discreet components may be referred to as bicomponent fibers.

Webs or fabrics made with spunmelt fibers may be referred to as “spunmelt webs or fabrics.”

The term “spunbond fibers” as used herein means substantially continuous fibers or filaments having an average diameter in the range of 10-30 microns. Splitable bicomponent or multicomponent fibers having an average diameter in the range of 5-30 microns prior to splitting are also included.

The term “meltblown fibers” as used herein means substantially continuous fibers or filaments having an average diameter of less than 10 microns.

The measurement “filament diameter” or “fiber diameter” or “fiber thickness” is expressed in units of μm. The terms “filament diameter”, “fiber diameter” and “fiber thickness” can be used interchangeably. The terms “number of grams of filament per 9000 m” (also denier or den) or “number of grams of filament per 10000 m” (dTex) are used to express the degree of fineness or coarseness of a filament as they relate to the filament diameter (a circular filament cross-section is assumed) multiplied by the density of the material or materials used.

The term “fully bonded nonwoven” as used herein, and as well understood by one skilled in the art, refers to a nonwoven that has fibers that are fused to one another at bonding impressions via melting and solidification. Such a fabric might be used itself for various applications, e.g., converted into a diaper, etc., or used as a precursor for further treatment (e.g., hydrophilic spin finish application or hydraulic treatment). For example, a fully calender bonded nonwoven may be produced by passing a batt through a nip point between two heated rolls under pressure, thereby providing a pattern of fused embossed impressions in the fabric. The pressure and temperature within the nip are sufficient to soften and melt the individual fibers and to then weld them together using a pattern of protrusions on at least one of the heated rolls to create a series of fused bonding impressions where the majority of fibers within the fused bonding impression can no longer be distinguished as individual fibers. The bonding impressions results in fusion of fibers or in the case of bicomponent fibers in fusion of at least one component with the lowest melting temperature through the full thickness of the fabric. The roll temperature and pressure are adjusted dependent upon fabric formulation and basis weight. For example, a 20-25 gsm 100% polypropylene homopolymer spunbond is typically bonded at roll temperatures of >150 deg C. and with a nip pressure greater than 90 N/mm. Temperature/pressure settings are adjusted to handle different basis weights and or line speeds. Higher basis weights and/or line speeds may require increased nip pressures and/or temperatures to achieve a “fully” bonded fabric with fused bond points. It should be appreciated that tack bonding is not within the scope of the definition of “fully bonded” for the purposes of this disclosure.

The term “bond area percentage” as used herein represents a ratio of an area occupied by bonding impressions to a total surface of a nonwoven fabric expressed as a percentage and measured according to the Bond Area Percentage Method set forth herein.

With respect to the making of a nonwoven web material and the nonwoven web material itself, “cross direction” (CD) refers to the direction along the web material substantially perpendicular to the direction of forward travel of the web material through the manufacturing line in which the web material is manufactured. With respect to a batt moving through the nip of a pair of calender rollers to form a bonded nonwoven web, the cross direction is perpendicular to the direction of movement through the nip, and parallel to the nip.

With respect to the making of a nonwoven web material and the nonwoven web material itself, “machine direction” (MD) refers to the direction along the web material substantially parallel to the direction of forward travel of the web material through manufacturing line in which the web material is manufactured. With respect to a nonwoven batt moving through the nip of a pair of calender rollers to form a bonded nonwoven web, the machine direction is parallel to the direction of movement through the nip, and perpendicular to the nip.

A “bonding protrusion” or “protrusion” is a feature of a bonding roller at its radially outermost portion, surrounded by recessed areas. Relative the rotational axis of the bonding roller, a bonding protrusion has a radially outermost bonding surface with a bonding surface shape and a bonding surface shape area, which generally lies along an outer cylindrical surface with a substantially constant radius from the bonding roller rotational axis; however, protrusions having bonding surfaces of discrete and separate shapes are often small enough relative the radius of the bonding roller that the bonding surface may appear flat/planar; and the bonding surface shape area is closely approximated by a planar area of the same shape. A bonding protrusion may have sides that are perpendicular to the bonding surface, although usually the sides have an angled slope, such that the cross section of the base of a bonding protrusion is larger than its bonding surface. A plurality of bonding protrusions may be arranged on a calender roller in a pattern. The plurality of bonding protrusions has a bonding area per unit surface area of the outer cylindrical surface which can be expressed as a percentage, and is the ratio of the combined total of the bonding shape areas of the protrusions within the unit, to the total surface area of the unit.

A “bonding impression” or “fused bonding impression” in a nonwoven web is the structure created by the impression of a bonding protrusion on a calender roller into a nonwoven web. A bonding impression is a location of deformed, intermeshed or entangled, and melted or thermally fused, materials from fibers superimposed and compressed in a z-direction beneath the bonding protrusion, which form a bond or a bonding area. The individual bonds may be connected in the nonwoven structure by loose fibres between them. The shape and size of the bonding impression approximately corresponds to the shape and size of the bonding surface of a bonding protrusion on the calender roller. For the purposes of this disclosure a “bonding impression thickness” is understood to mean a width of a bonding impression area in a nonwoven web plane. One or both of the rollers may have their circumferential surfaces machined, etched, engraved or otherwise formed to have thereon a bonding pattern of bonding protrusions and recessed areas, so that bonding pressure exerted on the batt at the nip is concentrated at the bonding surfaces of the bonding protrusions, and is reduced or substantially eliminated at the recessed areas. The bonding surfaces have bonding surface shapes. As a result, an impressed pattern of bonds between fibers forming the web, having bond impressions and bond shapes corresponding to the pattern and bonding surface shapes of the bonding protrusions on the roller, is formed on the nonwoven web. A repeating pattern of bonding protrusions and recessed areas may be formed onto a bonding roller. The bonding shapes depict raised surfaces of bonding protrusions on a roller, while the areas between them represent recessed areas. The bonding shapes of the bonding protrusions impress like-shaped bond impressions on the web in the calender bonding (or calendering) process.

FIG.1is a block diagram showing various components used in a process for making an apertured nonwoven web according to an exemplary embodiment of the present invention. Although the process shown inFIG.1results in a nonwoven web having an SMS structure (2;3;4), it should be appreciated that the process may be re-configured to form many other web structures comprising one or more spunbond layers and/or one or more meltblown layers, such as, for example, fabrics with single or multiple spunbond layers, more specific examples being S, SS, SSS, etc.; fabrics with a combination of spunbond and meltblown layers, typically with a spunbond layer forming at least one outer surface of the fabric, more specific asymmetric composition examples being SSMS, SMSSMMS, SSMMS, SMMMSS etc. fabrics or symmetric examples being SMS, SMMS, SMMMS, SSMSS etc. fabrics; fabrics combining spunmelt layers with other layers, more specific examples being a combination of spunmelt layers formed of endless filaments with short fibers formed from natural materials, etc. The nonwoven web structure is not limited to the examples provided herein, and one of ordinary skill in the art would understand that many other such structures may be obtained by varying the number and arrangement of process components.

In general, it should be appreciated that the number and configuration of beams is not limited to that shown and described herein, and in other exemplary embodiments, the number and configuration of beams may be varied to achieve different web structures. For example, a single spunbond beam may be used to form nonwoven batt6on conveyor belt8having a single spunbond layer, or multiple spunbond beams may be used to form batt6having a multi-spunbond layer structure, such as, for example SS, SSS, SSSS, etc. Layers formed by multiple beams might be the same or very similar to each other in terms of filament-type, process parameters, etc. so that the layers are substantially indistinguishable from one another to thereby form what appears to be a single layer structure or they might be produced differently from one another thereby forming an evidently layered nonwoven product.

In another exemplary embodiment, only spunbond beam2and meltblown beam3are used to form nonwoven batt6on conveyor belt8. According to further exemplary embodiments of the invention, plural elements corresponding to beams2,3may be incorporated in the system to form batt6with multiple respective layers, such as, for example SM, SMM, SSM, SSMM etc. Again, layers formed by multiple beams, typically multiple beams of same type, might be the same or very similar to each other in terms of filament-type, process parameters, etc. so that the layers are substantially indistinguishable from one another to thereby form what appears to be a single layer structure or they might be produced differently from one another thereby forming an evidently layered nonwoven product.

According to an exemplary embodiment of the invention, a spunmelt nonwoven batt6is made of continuous filaments that are laid down on a moving conveyor belt8in a randomized distribution. Resin pellets may be processed under heat into a melt and then fed through a spinneret (or spinning beams2and4) to create hundreds of filaments by use of a drawing device (not shown). Multiple spinnerets or beams (blocks in tandem) may be used to provide an increased density of spunbond fibers corresponding to, for example, each of spinning beams2and4. Jets of a fluid (such as air) cause the fibers from beams2and4to be elongated, and the fibers are then blown or carried onto a moving web (conveyor belt)8where they are laid down and sucked against the web8by suction boxes (not shown) in a random pattern to create a batt6. A meltblown layer may be deposited by a meltblown mechanism (or “beam”)3, preferably between spunbond layers laid by spinning beams2and4. The meltblown (“MB”) layer can be formed by a meltblown process but may be formed by a variety of other known processes. For example, the meltblowing process includes inserting a thermoplastic polymer into a die. The thermoplastic polymer material is extruded through a plurality of fine capillaries in the die to form fibers. The fibers stream into a high velocity gas (e.g. air) stream which attenuates the streams of molten thermoplastic polymer material to reduce their diameter, which may be to the microfiber diameter. The meltblown fibers are quasi-randomly deposited by beam3over the moving web or moving web with spunbond layer laid by spinning beam2to form a meltblown layer. One, two or more meltblown blocks may be used in tandem in order to increase the coverage of fibers. The meltblown fibers can be tacky when they are deposited, which generally results in some bonding between the meltblown fibers of the web.

In a preferred embodiment, the fibers used to form batt6are thermoplastic polymers, examples of which include polyolefins (e.g. polypropylene “PP” or polyethylene “PE”), polyesters (e.g., polylactic acid “PLA” or polyhydroxyalkanoates “PHA” or polyhydroxybutyrate “PUB” or polybutylene succinate “PBS” or polyethylene terephthalate “PET”, etc.), polyamides, polysaccharides (e.g. thermoplastic starch “TPS” or starch based polymers, etc.) copolymers thereof (with olefins, esters, amides or other monomers) and blends thereof. Preferably the fibers are made from polyolefins, examples of which include polyethylene, polypropylene, propylene-butylene copolymers thereof and blends thereof, including, for example, ethylene/propylene copolymers and polyethylene/polypropylene blends. Resins with higher crystallinity and lower break elongations may also be suitable due to likelihood to fracture with greater ease. Fibers might be also formed, for example, from non-oil-based components, such as aliphatic polyesters, thermoplastic polysaccharides or other biopolymers, or they may contain these substances as additives or modifiers. As used herein, the term “blend” includes a homogeneous or semi-homogenous mixture of at least two polymers.

Another approach has involved forming a nonwoven web of multicomponent or preferably “bicomponent” polymer fibers. Such bicomponent polymer fibers may be formed by spinnerets that have two adjacent sections, that express a first component from one polymer or blend and a second component from the other, to form a fiber having a cross section of the first component in one portion and the second component in the other (hence the term “bicomponent”). The respective components may be with advantage selected to have differing melting temperatures and/or expansion-contraction rates. These differing attributes of the two polymers, when combined in a side by side or asymmetric sheath-core geometry might cause the bicomponent fiber products to curl in the spinning process, as they are cooled and drawn from the spinnerets. The resulting curled fibers then may be laid down in a batt and calender bonded in a pattern. It is thought that the curl in the fibers adds loft and fluff to the web, enhancing visual and tactile softness signals.

Other formulation changes may also be employed, e.g., addition of CaCO3, to provide a spunbond fiber that is more prone to fracture and/or permanent deformation and, thus, provide improved aperturing. One skilled in the art would appreciate many other formulation changes, such as, for example, color additives, process additives, filament surface modulators, such as, for example, softness enhancers, etc., dependent on further requirements of the final fabric properties or specific spunmelt line requirements.

In an exemplary embodiment, batt6may be thermally calender-bonded via rollers10and12. One or both rollers10and12may have their circumferential surfaces machined, etched, engraved or otherwise formed to have thereon a pattern of protrusions and recessed areas, so that bonding pressure exerted on the batt6at the nip is concentrated at the outward surfaces of the protrusions, and reduced or substantially eliminated at the recessed areas. According to an exemplary embodiment of the invention, roller10is a calender roll and roller12is a bonding roll defining a bond pattern. The thermal calender bonding results in a fully bonded precursor web7. Preferred bond patterns in accordance with exemplary embodiments of the present invention are described further below.

In accordance with an exemplary embodiment of the invention, precursor nonwoven web7is then hydraulically treated using multiple water jet injectors16a,16b, and16c. Each of elements16a,16b, and16cillustrated inFIG.1may represent a set of plural injectors in a respective predetermined arrangement. According to an exemplary embodiment of the invention, as precursor nonwoven web7is conveyed under the injectors16a-cby a belt22, high pressure water jets of the injectors16a,16b,16cact against and pass through the fabric. In an exemplary embodiment, the belt22comprises a pattern of pins for imparting apertures to the precursor nonwoven web7. According to an exemplary embodiment of the invention, the pins have a base, and a distance between centers of immediately adjacent pins is at least 100% of a diameter of the base, and in a preferred exemplary embodiment, 150% of a diameter of the base.

Corresponding water removal systems20a,20b, and20cmay be positioned under the location of each injector (set)16a-cto pull the water away and dry the precursor fabric7. The water removal systems20a,20band20cmay include, for example, vacuum boxes, suction boxes, Uhle boxes, fans and/or vacuum slots. Nonwoven precursor web7may subsequently be dried by blowing hot air through the fibrous web, by IR dryers or other drying techniques (e.g., air drying).

According to an exemplary embodiment of the invention, belt22may incorporate one or more screens (not shown) each with a predetermined pattern for supporting precursor nonwoven web7while it is being hydraulically treated by respective water injectors16a-16c. As explained in further detail below with reference toFIGS.2A and2B, the one or more screens may be replaced with one or more drums14, with the one drum or the last drum in a series of drums provided with a sleeve18. The screen(s) or sleeve may comprise a pattern of pins for imparting apertures to the precursor nonwoven web7. According to exemplary embodiments of the invention, fewer than three sets of injectors16a-16cmay be used for hydraulically treating and/or imparting apertures to precursor nonwoven web7.

In accordance with an exemplary embodiment of the invention, the use of one or more drums, with the one drum or the last drum in a series of drums having a sleeve provided with a pattern of pins, and further with each drum being associated with one or more water injectors, results in a plurality of steps of water injection. The desired water pressure at each step depends on a number of parameters, including the number of water injection steps and the line speed. In general, the more water injection steps used in the process, the less pressure is required at each step to achieve the desired fabric properties. In other words, the energy flux attained using a number of water injectors each applying an amount of water pressure can also be attained by increasing the number of water injectors and decreasing the amount of water pressure applied by each injector. The desired water pressure at each step also depends at least partially on the line speed. Higher line speed requires higher pressure to maintain constant flux. In other words, the energy flux attained using a line speed and injector pressure can also be attained by reducing both the line speed and injector pressure.

Without being bound by theory, it is believed the preferred total water jet pressure applied to the precursor web7may be expressed in terms of energy flux. In accordance with an exemplary embodiment, the preferred energy flux applied to the precursor web7is at least 0.2 kWh/kg, preferably at least 0.3 kWh/kg, preferably at least 0.5 kWh/kg, preferably within the range of 0.2-3.0 kWh/kg, preferably within the range of 0.3-1.9 kWh/kg and also preferably within the range of 0.5-1.9 kWh/kg. The desired energy flux may be obtained by, for example, varying machine speed and/or water pressure at each water injector. Preferably, the desired energy flux is achieved by using one or more water injectors at a relatively lower pressure rather than less water injectors at a higher pressure. Energy flux may be calculated using the following formula:

Flux=J1.5×G2*I*L1*1⁢03*71*1⁢01⁢0F⁢kWh/kg

In exemplary embodiments in which a series of drums are used, the pins on the last drum in the process line provide the entire aperturing of the precursor web7. In this regard, the drums before the last drum in the process line are preferably not provided with pins, but instead may be provided with mesh screens. In an exemplary embodiment, the second to last drum in a line of drums may be provided with pins to prepare the precursor fabric for aperturing, but again the actual opening/aperturing of the precursor fabric7preferably occurs at the last drum. It should be appreciated that in other exemplary embodiments of the present invention, the pins may be provided on a belt rather than on a drum.

Preferred exemplary embodiments of the present invention involve the use of a relatively large amount of water injectors. Without being bound by theory, the use of a larger amount of injectors allows for higher line speed without having to increase injector pressure. It should be noted, that for the purposes of the present disclosure, two or more water injectors with the same settings (especially concerning number and geometry of water jets and the water pressure) are considered a single water injector.

In an exemplary embodiment, the plurality of steps of water injection may include exposing the fully calender-bonded polyolefin based nonwoven precursor web7to a plurality of water injectors with each water injector applying a pressure of 180 bar, preferably 200 bar or greater. In exemplary embodiments, the basis weight of the precursor web7is 15 gsm to 45 gsm and the line speed is 150 to 450 meters/minute, with a more specific example in which the precursor web has a basis weight of 25 gsm and the line speed is 200 meters/minute.

In an exemplary embodiment, the plurality of steps of water injection may include exposing the fully calender-bonded polyolefin based nonwoven precursor web7to two water injectors with each water injector applying a pressure of 250 bar, preferably 300 bar or greater. In exemplary embodiments, the basis weight of the precursor web7is 15 gsm to 45 gsm and the line speed is 150 to 450 meters/minute, with a more specific example in which the precursor web has a basis weight of 25 gsm and the line speed is 200 meters/minute.

In an exemplary embodiment, the plurality of steps of water injection may include exposing the fully calender-bonded polyolefin based nonwoven precursor web7to at least four water injectors with each water injector applying a pressure of 150 bar or greater. In exemplary embodiments, the basis weight of the precursor web7is 15 gsm to 45 gsm and the line speed is 150 to 450 meters/minute, with a more specific example in which the precursor web has a basis weight of 25 gsm and the line speed is 200 meters/minute.

In an exemplary embodiment, the plurality of steps of water injection may include exposing the fully calender-bonded polyester based nonwoven precursor web7to at least three water injectors applying a pressure of 60 bar, preferably 75 bar or greater. In exemplary embodiments, the basis weight of the precursor web7is 15 gsm to 45 gsm and the line speed is 150 to 450 meters/minute, with a more specific example in which the precursor web has a basis weight of 25 gsm and the line speed is 200 meters/minute.

In exemplary embodiments, the plurality of steps of water injection includes exposing the fully calendar-bonded nonwoven precursor web7to three water injectors (with each water injector having a set of injectors/nozzles), with each water injector applying a higher amount of pressure as compared to an immediately preceding water injector in the machine direction. For example, the water injector16cmay apply a higher pressure as compared to the water injector16b, and the water injector16bmay apply a higher pressure as compared to the water injector16a. In a specific exemplary embodiment, the water injector16bapplies pressure in the amount of at least 80%, preferably 80% to 95% of the pressure applied by water injector16c, and the water injector16aapplies pressure in the amount of at least 80%, preferably 80% to 95% of the pressure applied by water injector16b. In embodiments, the water injector16aapplies pressure in an amount of at least 64%, preferably 64% to 90% of the pressure applied by water injector16c. The relatively low pressure applied by water injector16aresults in initial softening of the precursor web without opening of apertures, the higher pressure applied by the water injector16bprepares the precursor web for aperturing by beginning to alter the individual bond impressions (as explained in further detail below) and the final water injector16cin the machine direction applying the highest amount of pressure creates the apertures in the precursor web and further alters the individual bond impressions. Without being bound by theory it is believed that the rising gradient in applied pressure helps to preserve individual bond impressions in the softening and preparation stages of the process and allows for controlled altering of individual bond impressions together with creation of apertures at the last stage.

In embodiments, the plurality of steps of water injection includes exposing the fully calendar-bonded nonwoven precursor web7to two water injectors (with each water injector having a set of injectors/nozzles), with each water injector applying a higher amount of pressure as compared to an immediately preceding water injector in the machine direction. For example, the water injector16cmay apply a higher pressure as compared to the water injector16b, and the water injector16amay be excluded.

In embodiments, the plurality of steps of water injection includes exposing the fully calendar-bonded nonwoven precursor web7to four or more water injectors (with each water injector having a set of injectors/nozzles), with each water injector applying a higher amount of pressure as compared to an immediately preceding water injector in the machine direction.

In exemplary embodiments, the step of hydraulically imparting the fully bonded precursor nonwoven web with a plurality of apertures comprises at least partially altering the individual bond impressions by application of water pressure. In this regard, application of water pressure may result in removal of at least some of the fully bonded portions of the individual bond impressions so that at least 60%, preferably at least 70%, more preferably 80%, and even more preferably 90% of the fully bonded portions of the individual bond impressions remain after the step of hydraulically imparting.

In embodiments, application of water pressure may result in separation of the individual bond impressions into at least two portions. In embodiments, application of water pressure may result in reduction in overall size of the individual bond impressions while maintaining the general profile of the individual bond impressions. For example, as shown inFIGS.20A-20B,22A and22B, in the case of oval bond impressions (e.g., Pattern1), the alteration may result in reduction in size of the oval shape while maintaining the general oval profile of the bonding impression. As a further example, as shown inFIGS.21A-21B,23A and23B, in the case of S-shape bond impression (e.g., Pattern3) with bonding areas in the shape of relatively narrow line forming an S-shape, the alteration may result in separation of the S-shaped line into several portions. Without being bound by theory, it is believed that the at least partial alteration of the individual bond impressions results in tactile softness improvement and does not significantly reduce tensile strength and/or abrasion resistance of the final product. Tactile softness is a complex value that is hard to express by simple measurement, as it represents the feeling provided by human fingers. Values measured in this application (caliper, HOM, COF) are partial measurements of tactile softness and their values do not express tactile softness in its complexity.

In embodiments, as shown inFIGS.19A-19F, application of water pressure results in fibers in areas around perimeters of the individual bond impressions being randomly frayed in and out of a major plane of the fully bonded precursor nonwoven web so as to at least partially remove naturally reinforced fibers around the perimeters of the bond impressions to thereby at least partially eliminate the three-dimensionality of the individual bond impressions. More specifically,FIG.19Ais a cross-sectional view showing formation of an individual bond impression with a patterned calender roll12and smooth calender10with naturally reinforced fibers at the bond impression edge,FIG.19Bis a cross-sectional view of the bonded precursor web with an individual bond impression100and naturally reinforced fibers at the bonding impression edge, andFIG.19Cis a cross-sectional view showing the hydraulically treated nonwoven web with an altered individual bond impression where there are no naturally reinforced fibers at the bonding impression edge and also the bonding impression itself is slightly smaller.FIG.19Dis a micrograph of a cross-section of an altered individual bond impression according to an exemplary embodiment of the present invention showing how the hydraulic treatment results in frayed edges around the bond impression with no naturally reinforced fibers around the bond impression perimeter. In contrast,FIGS.19E and19Fare micrographs of a cross-section of a conventional precursor bonding impression as shown in U.S. Pat. No. 8,410,007, where the naturally reinforced fibers are clearly visible.

Without being bound by theory, it is believed that the randomization of fibers around the perimeter of the individual bond impressions results in softer final product (tactile softness).

FIGS.2A and2Billustrate exemplary embodiments of the invention employing one or plural drums for imparting apertures in a nonwoven fabric. Like elements are labeled with the same reference numerals as those inFIG.1and repeated detail description of these elements is omitted here.

As shown inFIG.2A, spunbond beam2, meltblown beam3and spunbond beam4may be used to form batt6on conveyor belt8. The batt6may then be bonded with calender rolls10and12to form a fully-bonded precursor nonwoven7. Again, according to further exemplary embodiments of the invention, plural elements corresponding to each of beams2,3,4may be incorporated in the system to form multiple respective layers of batt6by, for example, depositing multiple meltblown layers to form an SM or SMS type of fabric. It should be appreciated that the number, type and arrangement of beams are not limited to those described and shown herein, and it should be appreciated that any other combination of meltblown, spunbond, and/or meltblown/spunbond web structures may be formed in accordance with exemplary embodiments of the present invention by varying the number, type and/or arrangement of beams.

In accordance with an exemplary embodiment of the invention, apertures are then hydraulically imparted to nonwoven precursor web7by passing web7around drum14as one or more water injectors16apply pressurized water to the web7. According to an exemplary embodiment of the invention, drum14may be covered with a sleeve18, which may be made with metal or plastic, having a predetermined pattern of pins that form apertures in the precursor fabric/web7under the influence of the water pressure applied by the water injectors16. According to an exemplary embodiment of the invention, the pins have a base, and a distance between centers of the pins is at least 100% of a diameter of the base, preferably of at least 150% of a diameter of the base, more preferably at least 200% of the diameter of the base. For the purposes of this measurement, the base is taken to mean the portion of the pin just before the pin begins to flare outwards into contact with the flat portions of the sleeve, as shown inFIG.3. In situations where the pin base is not circular, the “diameter” is taken to mean the length of the shortest dimension across the pin base (for example, if the pin has an oval shape, the “diameter” would be the length of the minor axis of the oval).

Precursor nonwoven web7is wrapped around the drum14and as it passes under the injectors16, high pressure water jets of the injectors16act against the fabric and pass through the fabric to deform the fabric according to the pin pattern on the sleeve18. A water removal system20may be positioned under the location of each injector16to pull the water away, or through the apertures, thereby forming apertures in the precursor fabric (web7) in a pattern corresponding to that of the pins on the sleeve18below the fabric7. The apertured nonwoven web9may subsequently be dried by blowing hot air through the fibrous web, by IR dryers or other drying techniques (e.g., air drying).

In accordance with exemplary embodiments of the invention, heights of the pins are at least 100% of a thickness of the apertured nonwoven web, preferably at least 115% of a thickness of the apertured nonwoven web, more preferably at least 130% of a thickness of the apertured nonwoven web, wherein the thickness of the apertured nonwoven web is measured on a final dry product. The height of the pins for the purposes of this disclosure is taken to mean the height as measured from the base of the pin as described above to the top of the pin.

In accordance with exemplary embodiments of the invention, heights of the pins are at least 150% of a thickness of the precursor, preferably at least 200% of a thickness of the precursor web, preferably at least 250% of a thickness of the precursor web, more preferably at least 300% of a thickness of the precursor web wherein the thickness of the precursor nonwoven web is measured on a dry precursor before entering the water treatment.

As shown inFIG.2A, aperturing may be done on one drum14with at least one, preferably multiple, water jet beams (injectors16) so that subsequent drums will not disrupt the clarity of the aperturing pattern.

In accordance with an exemplary embodiment of the invention, the use of the single drum14inFIG.2Ahaving a sleeve provided with a pattern of pins, with the single drum14being associated with one or more water injectors, results in a plurality of steps of water injection. The desired water pressure at each step depends on the number of water injection steps. In accordance with an exemplary embodiment, the preferred energy flux applied to the precursor web7is within the range of 0.2-3.0 kWh/kg, preferably within the range of 0.3-1.9 kWh/kg. The desired energy flux may be obtained by, for example, varying machine speed and/or water pressure at each water jet. Preferably, the desired energy flux is achieved by using one or more water injection stations at a relatively low pressure rather than less water injection stations at a higher injector pressure.

In an exemplary embodiment, the plurality of steps of water injection may include exposing the fully calender-bonded nonwoven precursor web7as the web7travels around the single drum14to a three sets of water injectors with each water injector applying a pressure of 200 bar or greater. In exemplary embodiments, the basis weight of the precursor web7is 15 gsm to 45 gsm and the line speed is 150 to 450 meters/minute, with a more specific example in which the precursor web has a basis weight of 25 gsm and the line speed is 200 meters/minute.

In an exemplary embodiment, the plurality of steps of water injection may include exposing the fully calender-bonded nonwoven precursor web7as the web7travels around the single drum14to two sets of water injectors with each water injector applying a pressure of 250 bar or greater. In exemplary embodiments, the basis weight of the precursor web7is 15 gsm to 45 gsm and the line speed is 150 to 450 meters/minute, with a more specific example in which the precursor web has a basis weight of 25 gsm and the line speed is 200 meters/minute.

In an exemplary embodiment, the plurality of steps of water injection may include exposing the fully calender-bonded nonwoven precursor web7as the web7travels around the single drum14to at least four sets of water injectors with each water injector applying a pressure of 150 bar or greater. In exemplary embodiments, the basis weight of the precursor web7is 15 gsm to 45 gsm and the line speed is 150 to 450 meters/minute, with a more specific example in which the precursor web has a basis weight of 25 gsm and the line speed is 200 meters/minute.

FIG.2Bshows a system for imparting apertures to a nonwoven web using more than one drum according to an exemplary embodiment of the present invention. As shown inFIG.2B, spunbond beam2and meltblown beam3may be used to form batt6on conveyor belt8. The batt6may then be bonded with calender rolls10and12to form a fully-bonded precursor nonwoven web7. Again, according to further exemplary embodiments of the invention, plural elements corresponding to each of beams2,3may be incorporated in the system to form multiple respective layers of batt6—for example, depositing multiple meltblown layers to form an SMMS or SMMMS fabric. Again, it should be appreciated that the number, type and arrangement of beams are not limited to those described and shown herein, and it should be appreciated that any other combination of meltblown, spunbond, and/or meltblown/spunbond web structures may be formed in accordance with exemplary embodiments of the present invention by varying the number, type and/or arrangement of beams.

As shown inFIG.2B, the process in accordance with this exemplary embodiment involves the use of two drums, first drum14aand second drum14b, where second drum14bfollows first drum14aalong the process line. It should be appreciated that the number of drums is not limited to two, and any number of drums may be used. In accordance with an exemplary embodiment of the invention, apertures are hydraulically imparted to nonwoven precursor web7by passing web7around drum14b(the last drum in the line of two drums) as one or more water injectors16bapply pressurized water to the web7. According to an exemplary embodiment of the invention, drum14bmay be covered with a sleeve18, which may be made with metal or plastic, having a predetermined pattern of pins that form apertures in the precursor fabric/web7. According to an exemplary embodiment of the invention, the pins have a base, and a distance between centers of the pins is at least 100% of a diameter of the base, preferably of at least 150% of a diameter of the base, more preferably at least 200% of the diameter of the base.

Precursor web7is wrapped around the drum14aand14b, and as the web7passes under the injectors16bassociated with the second drum14b, high pressure water jets of the injectors16bact against the fabric and pass through the fabric to deform the fabric according to the pin pattern on the sleeve18. A water sink or vacuum slot/area20a,20bmay be positioned under the location of each injector16a,16bto pull the water away, or through the apertures, thereby forming apertures in the precursor fabric (web7) in a pattern corresponding to that of the pins on the sleeve18below the fabric7. The apertured nonwoven web9may subsequently be dried by blowing hot air through the fibrous web, by IR dryers or other drying techniques (e.g., air drying).

The entirety of the aperturing is preferably performed at the second (last in line) drum14bwith at least one, preferably multiple, water jet beams (injectors16b) so that subsequent drums will not disrupt the clarity of the aperturing pattern. In this regard, the drums before the last drum (for example, drum14a) in the process line are preferably not provided with pins, but instead may be provided with mesh screens. In an exemplary embodiment, the second to last drum in a line of drums may be provided with pins to prepare the precursor fabric for aperturing, but again the actual opening/aperturing of the precursor fabric7preferably occurs at the last drum.

In accordance with an exemplary embodiment of the invention, the use of only the last drum14b(in the line of drums) having a sleeve provided with a pattern of pins, with the drum14bbeing associated with one or more water injectors, results in a plurality of steps of water injection. The desired water pressure at each step depends on the number of water injection steps. In accordance with an exemplary embodiment, the preferred energy flux applied to the precursor web7is within the range of 0.2-3.0 kWh/kg, preferably within the range of 0.3-1.9 kWh/kg. The desired energy flux may be obtained by, for example, varying machine speed and/or water pressure at each water jet. Preferably, the desired energy flux is achieved by using one or more water injection stations at a more moderate pressure rather than less water injection stations at a higher injector pressure.

In an exemplary embodiment, the plurality of steps of water injection may include exposing the fully calender-bonded nonwoven precursor web7as the web7travels around the drum14bto three water injectors with each water injector applying a pressure of 300 bar or greater. In exemplary embodiments, the basis weight of the precursor web7is 15 gsm to 45 gsm and the line speed is 150 to 450 meters/minute, with a more specific example in which the precursor web has a basis weight of 25 gsm and the line speed is 200 meters/minute.

In an exemplary embodiment, the plurality of steps of water injection may include exposing the fully calender-bonded nonwoven precursor web7as the web7travels around the drum14bto two water injectors with each water injector applying a pressure of 250 bar or greater. In exemplary embodiments, the basis weight of the precursor web7is 15 gsm to 45 gsm and the line speed is 150 to 450 meters/minute, with a more specific example in which the precursor web has a basis weight of 25 gsm and the line speed is 200 meters/minute.

In an exemplary embodiment, the plurality of steps of water injection may include exposing the fully calender-bonded nonwoven precursor web7as the web7travels around the drum14bto at least four water injectors with each water injector applying a pressure of 150 bar or greater. In exemplary embodiments, the basis weight of the precursor web7is 15 gsm to 45 gsm and the line speed is 150 to 450 meters/minute, with a more specific example in which the precursor web has a basis weight of 25 gsm and the line speed is 200 meters/minute.

Without being bound by theory, it is believed that precursor nonwoven web properties have a strong influence on final fabric features. The fully bonded precursor nonwoven web is exposed to hydro-patterning as discussed herein, which forces the fibers in the web to shape around the pins on the screen through movement of fibers, breakage and/or inelastic deformation. This shape remains in the web and therefore provides a desired level of aperture clarity together with improvements in other attributes, such as, for example, softness, mechanical stability, etc. Important features of the precursor nonwoven according to exemplary embodiments of the present invention are described below.

In an exemplary embodiment, the precursor nonwoven web may have a Bond Area Percentage preferably at least 5%, preferably at least 10%, more preferably in the range of 10% to 25%. The “Bond Area Percentage” on a nonwoven web is a ratio of area occupied by bond impressions, to the total surface area of the web, expressed as a percentage, and measured according to the Bond Area Percentage method set forth herein. The method for measuring Bond Area Percentage is described in U.S. Pat. No. 8,841,507, the contents of which are herein incorporated by reference in their entirety, and also described below.

In an exemplary embodiment, the precursor nonwoven web may have a bond pattern made up of a number of bonding impressions, with each bonding impression having a greatest measurable length and a greatest measurable width.

FIG.4shows a bonding pattern, referred to herein as “Pattern3”, on a precursor nonwoven web according to an exemplary embodiment of the present invention. The bonding shape100of each bonding impression has a greatest measurable length L, which is measured by identifying a shape length line104intersecting the perimeter of the shape at points of intersection that are the greatest distance apart that may be identified on the perimeter, i.e., the distance between the two farthest-most points on the perimeter. The bonding shape100has a greatest measurable width W which is measured by identifying respective shape width lines105a,105bwhich are parallel to shape length line104and tangent to the shape perimeter at one or more outermost points that are most distant from shape length line104on either side of it, as reflected inFIG.4. It will be appreciated that, for some shapes (e.g., a semicircle), one of shape width lines105a,105bmay be coincident/colinear with shape length line104. The greatest measurable width W is the distance between shape width lines105a,105b.

Shapes within the scope of the present invention have an aspect ratio of greatest measurable length L to greatest measurable width W of at least 1.0, preferably of at least 1.5, more preferably of at least 2.0, even more preferably of at least 2.5. For example, an oval within a pattern of ovals (referred to herein as a “Pattern1”) in accordance with an exemplary embodiment of the present invention has an aspect ratio of greatest measurable length L to greatest measurable width W of 1.8, and a straight line within a pattern of straight lines (referred to herein as “Pattern2”) has an aspect ratio of greatest measurable length L to greatest measurable width W of 8.5. The bond shapes and sizes impressed on the nonwoven web will reflect and correspond with the bonding shapes100and sizes thereof on the calender roller.

Without intending to be bound by theory, it is believed that calender roller bonding protrusions having bonding shapes with one or more features as described herein have aerodynamic effects on air flow in and about the calender nip, that cause acceleration and deceleration of air in and about the interstices of the nonwoven fibers in a way that repositions the fibers. This repositioning of fibers may effect teasing or fluffing that can be advantageous in terms of forming aperture shape around pins during the hydro-patterning processes as described herein.

Additionally, the rotational orientations of the protrusions have an aerodynamic effect. In an exemplary embodiment, patterns with spaced bonding impressions have bonding shapes100and the bonding protrusions supporting them may be arranged along an individual shape tilt angle relative the machine and cross directions. Without intending to be bound by theory, it is believed that the shape tilt angle should not exceed a certain amount for the bonding protrusion to have maximum beneficial effect on air flow. Referring again toFIG.4, the shape tilt angle αT may be expressed as the smaller angle formed by the intersection of an axis along the machine direction108and the shape length line104. It is believed that the shape and the shape tilt angle have cooperating effects on the air flow. It is believed that the shape tilt angle αT provides the desired effects on air flow, such that it then should not exceed 65 degrees, more preferably, 40 degrees, and still more preferably, 30 degrees. It is believed that a shape tilt angle within this range effectively provides air flow through the nip, while at the same time, imparts cross-direction vector components to air flows through the nip. Conversely, a shape tilt angle greater than 50 degrees may create too much of an obstruction to air flow through the nip to have a beneficial effect, and even greater shape tilt angles combined with sufficient density of bonding protrusions may have the effect of creating enough obstruction at the nip to substantially divert airflow from the nip, i.e., toward the sides of the bonding rollers, rather than through the nip. The bond shapes and rotational orientations impressed on the nonwoven web will reflect and correspond with the bonding shapes and rotational orientations on the roller.

In other exemplary embodiments of the present invention, bonding impressions form a so called “quilted pattern.” For the purposes of the present description, a nonwoven with a quilted pattern is one that has relatively large and regularly spaced unbonded areas. The unbonded areas are formed by the intersection of bond lines that extend from the opposite edges of the nonwoven and cross the fabric usually in a diagonal direction. The bond lines are spaced apart from each other so that they leave an unbonded area between the lines. In exemplary embodiments, the surface area of the unbonded area is larger than the thickness of the bond lines as measured across the surface of the fabric. For example, referring toFIG.9(Pattern4), which shows a quilted pattern, the square shapes between the bond lines have a surface area that is preferably at least 3 times the thickness of the bond lines, preferably at least 4 times the thickness of the bond lines, most preferably at least 5 times the thickness of the bond lines. The bond lines may be formed by either unbroken lines or by individual bond points that are arranged in a consistent direction.

For quilted patterns, without being bound by theory, it is believed that the quilted pattern tilt angle αTq provides the desired effects on air flow, such that it then should not exceed 60 degrees, more preferably, 50 degrees, and still more preferably, 40 degrees. Referring toFIG.5, the pattern tilt angle αTq may be expressed as the smaller angle formed by the intersection of an axis along the machine direction108and the quilted pattern line104q.

Without being bound by theory, it is believed that a less homogenous filament direction in microscale tends to form more stable aperture edges in all directions. In contrast, a more homogenous microscale orientation might tend to form apertures with a higher density of filaments on the aperture edges aligned in a preferred direction. It is believed that, for best results, it may be even more desirable that the quilted pattern tilt angle αTqis between 5 degrees and 15 degrees, more preferably between 8 degrees and 12 degrees, and even more preferably between 9 degrees and 11 degrees. The rotational orientation of the bonding pattern impressed on the nonwoven web will reflect and correspond with the rotational orientation of the bonding pattern on the roller.

Still referring toFIG.4, a bonding shape100may have a shape perimeter with convex portions102a,102b, lying on either side of the shape length line104.FIG.4shows also that the convex portion may have a varying radius or radii. In other exemplary embodiments, the bonding shape100may include only a single convex portion (for example, to form a single arc shape rather than a multi-arc shape as shown inFIG.4). It is believed that a bonding protrusion having bonding surface, fitting this description, repeated and arranged in a pattern, has beneficial effects on acceleration and deceleration of air through nonwoven fibers at and about the nip and brings advantages in the formation of apertures in the fully bonded nonwoven around the pins. Again, the bond shapes and sizes impressed on the nonwoven web will reflect and correspond with the bonding shapes and sizes on the roller.

The shape perimeter may have a convex portion on either side of the shape length line, forming symmetric shapes such as, for example, circles, ovals, etc. Such a shape may be found in Pattern1as referred to herein.

The shape perimeter may have a convex portion with or without a varying radius on both sides of shape length line104, such that it has the overall contour of an airfoil with symmetrical camber, in cross section. In another alternative, the shape perimeter may have a convex portion on one side of shape length line104and a straight portion on or on the other side of shape length line104, such that it has the overall contour of an airfoil/aircraft wing with asymmetrical camber, in cross section. In another alternative, the shape perimeter may have a convex portion on one side of shape length line104and a concave portion103, disposed substantially opposite the concave portion, as reflected inFIG.4, with such shape being found in Pattern3as referred to herein.

Without limitation, Table 1 describes bonding patterns might be used in exemplary embodiments of the present invention:

TABLE 1Pattern 4Pattern 1Pattern 2Pattern 3(Large dotName(oval)(lines)(S shape)quilt)Pattern typeSpacedSpacedSpacedQuiltedbondingbondingbondingimpressionsimpressionsimpressionsBonding18%14%13%22%area percentageBonding49.992.411.1protrusions/cm2BondingSmallLargeLargeLarge + smallimpressionsize typeAngle αT60°0°10°45°L (mm)0.93.49.2Large: 2.8Small: 2.0W (mm)0.50.43.0Large: 2.8Small: 1.0L:W ratio1.88.53.1Large: 1Small: 2CorrespondingFIG. 6FIG. 7FIG. 8FIG. 9FIG.

Bond impression patterns1-3disclosed herein are formed of bonding impressions each with a finite area. Such bond impressions are called “discontinuous”. Bond impression pattern4has the smallest distance between adjacent bonding impressions 0.6 mm, so the bonding impressions are considered as one continuous bonding impression (quilted pattern).

From the presented examples it can be seen that the bonding impressions might have different sizes and so for a comparable bonding area the bonding pattern might look very different. For example, Pattern1has small bond points relatively close to each other (the number of bonding impressions per one square centimeter is approximately 50) while in contrast Pattern3provides large bonding impressions in a form of S-shaped lines relatively far from each other (the number of bonding impressions per one square centimeter is approximately 2.5). It should be noted that especially large bonding shapes or quilted patterns are preferably created by one large unitary bonding impression, but also can be made up of several smaller bonding impressions that form the overall bonding shape. For example, the individual S-shapes within Pattern3may be created from many smaller bond points or dots. For the purpose of the present disclosure, adjacent bonding impressions are considered as one bonding impression when the smallest distance between the adjacent bonding impressions is less than 0.7 mm, preferably less than 0.5 mm, even more preferably less than 0.4 mm, most preferably less than 0.3 mm.

In an exemplary embodiment, the precursor nonwoven web7has at least 20 bonding impressions per one square centimeter, preferably at least 30 bonding impressions per one square centimeter, more preferably at least 40 bonding impressions per one square centimeter, more preferably at least 50 bonding impressions per one square centimeter, even more preferably at least 60 bonding impressions per one square centimeter. For purposes of the present description, bonding impressions having values of bonding impressions per one square centimeter within these ranges are considered “small” size bonding impressions.

It might be unclear how to determine the number of bonding impressions per defined area for certain pattern designs. This situation may occur, for example, for patterns with several different types of bonding impression sizes or shapes, or for patterns with unbonded areas used as part of the design. In such cases, the bonding impressions are considered small when their total area (fused filaments area) is lower than 1 mm2.

Without being bound by theory, it is believed that the size and shape of the bonding impressions that make up the bonding pattern affects the final hydro-patterned fabric properties, such as, for example, aperture clarity, softness, stiffness and pattern visibility, to name a few. For example, in the case where the bonding impressions are small-sized and much smaller than the formed apertures, the bonding impressions are moved aside by the pins during the hydro-patterning process and therefore form a higher bonding impression density as compared to the precursor web, which in turn improves the stiffness of the apertured fabric product (seeFIG.10).

In accordance with another exemplary embodiment, the bonding impressions are large-sized and thus may be comparable in size to that of the apertures, and in exemplary embodiments may be larger in size as compared to the size of the apertures. Such relatively large bonding impressions may provide the precursor web with a relatively small bonding impression density, such as, for example, less than 20 bonding impressions per one square centimeter, preferably less than 15 bonding impressions per one square centimeter, more preferably less than 10 bonding impressions per one square centimeter, and even more preferably less than 5 bonding impressions per one square centimeter. For purposes of the present description, bonding impressions having values of bonding impressions per one square centimeter within these ranges are considered “large” size bonding impressions.

Without being bound by theory, it is believed that large bonding impressions on the precursor web7undergoing the above described hydraulic aperturing process might result in a fabric with a pattern of high clarity apertures where the bonding impressions are visible to the naked eye, thereby providing the fabric with a desirable and highly visible design of both apertures and bonding impressions.

Without being bound by theory it is believed that bonding impression shape and orientation in the MD/CD direction also influences the clarity of apertures and the integrity of the bonding pattern in the hydro-patterned fabric. For example, certain bonding pattern shapes might negatively interact with the pins during the hydro-patterning process, thereby resulting in decreased aperture clarity and a compromised bond pattern in the fabric. In contrast, bonding patterns with spaced bonding impressions, arranged in rows and/or columns, and/or with certain shapes, might avoid interference with the pin pattern, resulting in high clarity apertures with the bonding impressions visible and intact between the apertures.

Without being bound by theory, it is believed that during the hydro-patterning process, the large bonding impressions behave differentially than small ones. For example, the large impressions are not as easily moved aside during the hydro-patterning process, so that the bonding impression density is not significantly altered, if at all, as compared to that of the precursor web. For example, as shown inFIG.11, the S-shaped bonding impressions of Pattern3provides space for the pins arranged in a regular “square” pin-pattern to form apertures, and the shape, tilt and length to width ratio of the impressions provide enhanced aperture clarity in combination with enhanced mechanical properties, such as, for example, softness. As also seen inFIG.11, the S-shape bonding impressions of Pattern3are visible to the naked eye in the fabric, due to the bonding impressions' ability to “flow” around the pins during the hydro-patterning process.

As another example,FIG.12shows the bonding impressions of Pattern4(large dot quilt) being visible among the apertures, although not as evident as compared to Pattern3. Specifically, in this example, the precursor web was fully bonded using Pattern4made up of large circles and small diamonds very close together. The small diamonds act as small bonding impressions and are not clear to the naked eye after the hydro-patterning process. In contrast, the large circles of Pattern4remain visible, thereby forming in combination with the apertures a different visual effect as compared to the original thermo-bonded pattern on the precursor.

In an exemplary embodiment the precursor nonwoven web7provides bonding impressions with differing sizes. For example, WO2017190717 discloses a bonding pattern made up of primary and auxiliary bonding impressions. Under such circumstances, density of large and small bonding impressions should be judged separately. For example, small (or auxiliary) bonding impressions density should be estimated from the area without taking into account the large (or primary) bonding impressions.

In an exemplary embodiment, the precursor nonwoven web may have a stiffness expressed by Handle-O-Meter Test method (HOM). During the test the fabric is forced to bend into a nip having a relatively small scale (6.2 mm width, 8.0 mm deep) that is believed to be analogous to a filament bending around the pin. If the bending force is too small, the filaments act in an elastic manner and thus tend to come back to their original position after hydro-patterning, which in turn results in at least partial closing of the apertures after hydro-patterning. If the bending force is high, the filaments might tend to break and free ends of the filaments might interfere with the apertures, thereby decreasing aperture clarity level. Further, when the bending force is too high, the fabric resistance might not allow the pins to enter the structure and prevent formation of apertures.

In accordance with an exemplary embodiment, the precursor nonwoven web7has an MD HOM value of at least 5 g.

In accordance with an exemplary embodiment, the precursor nonwoven web7has an MD HOM value of maximum 30 g, preferably of maximum 25 g.

In exemplary embodiment, the precursor nonwoven web7has a CD HOM value of at least 2 g.

In accordance with an exemplary embodiment, the precursor nonwoven web7has CD HOM value of maximum 20 g, preferably of maximum 15 g.

In accordance with an exemplary embodiment, the apertured hydro-patterned nonwoven web9has a basis weight of 10 gsm to 45 gsm, preferably 20 gsm to 35 gsm.

In accordance with an exemplary embodiment, the apertured hydro-patterned nonwoven web9has a caliper of at least 12 microns/gsm of fabric.

In accordance with an exemplary embodiment, the apertured hydro-patterned nonwoven web9has a MD tensile strength of at least 4 N/cm.

In accordance with an exemplary embodiment, the apertured hydro-patterned nonwoven web9has a CD tensile strength of at least 2 N/cm.

In accordance with an exemplary embodiment, the apertured hydro-patterned nonwoven web9does not exhibit two-sidedness. This can be seen inFIGS.13and14showing naked eye and magnified photos of fabric according to exemplary embodiments of the present invention. The apertured hydro-patterned nonwoven web9does not exhibit two sidedness at least in terms of physical and material characteristics.

In contrast, most conventional aperturing techniques result in formation of three-dimensional or cone-like apertures, which in turn results in the final web product exhibiting two-sidedness. For example, conventional technologies using heat with needles/pins typically provide apertures with less desirable tactile feel due to the side at which the aperturing was initiated being clearly evident (seeFIG.15). The two-sidedness associated with conventional apertured web products may interfere with the performance of such products due to one side of the fabric exhibiting undesirable characteristics.

The apertured hydro-pattern nonwoven web9according to exemplary embodiments of the present invention exhibits relatively high levels of softness. This is at least partially due to the lack of sharp edges around the apertures. This is in contrast with most conventional technologies using heat to provide openings in fabric. It should be noted that softness itself is a very general term involving many various perceptions, some which might be expressed by measurements such as Handle-O-Meter, Cantilever test, compressibility, thickness, coefficient of friction and/or many other methodologies. Each test provides just partial limited information about softness and might be suitable for some applications or some ranges of basis weight, some polymer compositions, etc.

The nonwoven web9may be incorporated into a nonwoven laminate. The nonwoven laminate may include additional layers of continuous fibers such as spunbond fibers and meltblown fibers and may include composite nonwovens such as spunbond-meltblown-spunbond laminates. The nonwoven laminate may also include short fibers such as staple fibers or may include pulp fibers. These short fibers may be in the form of a consolidated web such as carded web or tissue sheet or may be initially unconsolidated. The nonwoven laminate may also include superabsorbent material, either in particulate form or in a fiberized form. The laminate may be formed through conventional means, including but not limited to thermal bonding, ultrasonic bonding, chemical bonding, adhesive bonding and/or hydroentanglement. In accordance with an embodiment of the invention, web9may form a nonwoven laminate resulting from the one or more processes described above for use as a topsheet, an absorbent core, or a backsheet of an absorbent article.

The following Examples and Comparative Examples illustrates advantages of the present invention.

Comparative Example 1 (Precursor Web to Example 1)

A 25 gsm spunmelt type nonwoven batt was produced online in a continuous process from a mixture of polypropylene (type 3155E5 from Exxon) with color additive (SCC 91056 from Standridge Color Corporation) and soft enhancing additive based on erucamide (CESA-slip PP 42161 from Avient), where monocomponent polypropylene filaments with a fiber diameter of 13-25 μm were produced and subsequently collected on a moving belt. The batt was produced on REICOFIL 3.1 technology (Reifenhauser Reicofil GmbH & Co. KG, Troisdorf, Germany) from four spunbond beams. The nonwoven batt was fully bonded by a pair of heated rollers, where one roller has raised Pattern3(FIG.8). The temperature of the calender rollers (smooth roller/patterned roller) was 160° C./162° C. and the bonding pressure was 75 N/mm. The resulting nonwoven web had material properties as shown in Table 2.

Example 1

The same nonwoven web was formed as described in Comparative Example 1, but with an additional step of hydro-patterning. The hydro-patterning was achieved with two drums, with the last drum in the line providing the web with apertures. The first drum had a wire mesh screen and two injectors at the drum, each applying a water pressure as shown in table 2. The first drum was used to hydrotreat the web before aperturing at the second drum. Each injector had two rows of holes, with the holes within each row spaced a distance of 0.6 mm from one another. The second drum had a screen with an A1 pattern of pins (pins spaced a distance of 4.5 mm from one another) as described herein. Three injectors applying water pressure as shown in table 2 were used to hydro-pattern the web with a pattern of apertures by forcing the web down onto the pins. The three injectors at the second drum each had two strips of holes, with the holes within each strip spaced a distance of 0.6 mm from one another. The aperturing process of Example 1 is summarized in Table 3. The resulting nonwoven web had material properties as shown in Table 2.

Comparative Example 2 (Precursor Web to Example 2)

A 25 gsm spunmelt type nonwoven batt was produced online in a continuous process from a mixture of polypropylene (Mosten NB425 from Unipetrol) and copolymer (Vistamaxx 6202 from Exxon) in the weight ratio 75:15, color additive (SCC 91056 from Standridge Color Corporation) and soft enhancing additive based on erucamide (CESA-slip PP 42161 from Avient), where monocomponent polypropylene filaments with a fiber diameter of 13-25 μm were produced and subsequently collected on a moving belt. The batt was produced on REICOFIL 3.1 technology from four beams. The nonwoven batt was fully bonded by a pair of heated rollers, where one roller had raised Pattern3(FIG.8). The temperature of the calender rollers (smooth roller/patterned roller) was 150° C./155° C. and the bonding pressure was 75 N/mm. The resulting nonwoven web had material properties as shown in Table 2.

Example 2

The same nonwoven web was formed as described in Comparative Example 2, but with an additional step of hydro-patterning. The hydro-patterning was achieved with two drums, with the last drum in the line providing the web with apertures. The first drum had a wire mesh screen and one injector at the drum applying a water pressure of 200 bar to hydrotreat the web before aperturing at the second drum. The one injector at the first drum had two rows of holes, with the holes within each strip spaced a distance of 1.2 mm from one another. The second drum had a screen with an A1 pattern of pins (pins spaced a distance of 4.5 mm from one another) as described herein. Three injectors applying water pressure of 220 bar, 220 bar and 250 bar, respectively, were used to hydro-pattern the web with a pattern of apertures by forcing the web down onto the pins. The three injectors at the second drum each had two strips of holes, with the holes within each strip spaced a distance of 0.6 mm from one another. The aperturing process of Example 2 is summarized in Table 3. The resulting nonwoven web had material properties as shown in Table 2.

Comparative Example 3 (Precursor Web to Example 3)

A 25 gsm spunmelt type nonwoven batt was produced online in a continuous process from a mixture of polypropylene (type 3155E5 from Exxon) with color additive (SCC 91056 from Standridge Color Corporation), where monocomponent polypropylene filaments with a fiber diameter of 13-25 μm was produced and subsequently collected on a moving belt. The batt was produced on REICOFIL 3.1 technology from four spunbond beams. The nonwoven batt was fully bonded by a pair of heated rollers, where one roller had raised Pattern2(FIG.7). The temperature of the calender rollers (smooth roller/patterned roller) was 160° C./162° C. and the bonding pressure was 75 N/mm. The resulting nonwoven web had material properties as shown in Table 2.

Example 3

The same nonwoven web was formed as described in Comparative Example 3, but with an additional step of hydro-patterning. The hydro-patterning was achieved with two drums, with the last drum in the line providing the web with apertures. The first drum had a wire mesh screen and one injector at the drum applying a water pressure of 200 bar to hydrotreat the web before aperturing at the second drum. The one injector at the first drum had two strips of holes, with the holes within each row spaced a distance of 1.2 mm from one another. The second drum had a screen with an A1 pattern of pins (pins spaced a distance of 4.5 mm from one another) as described herein. Three injectors applying water pressure of 220 bar, 220 bar and 250 bar, respectively, were used to hydro-pattern the web with a pattern of apertures by forcing the web down onto the pins. The three injectors at the second drum each had two strips of holes, with the holes within each strip spaced a distance of 0.6 mm from one another. The aperturing process of Example 3 is summarized in Table 3. The resulting nonwoven web had material properties as shown in Table 2.

Comparative Example 4 (Precursor Web to Example 4)

A 25 gsm spunmelt type nonwoven batt was produced online in a continuous process from a mixture of polypropylene (Mosten NB425 from Unipetrol) and copolymer (Vistamaxx 6102 from Exxon) in the weight ratio 75:15, color additive (SCC 91056 from Standridge Color Corporation) and soft enhancing additive based on erucamide (CESA-slip PP 42161 from Avient), where monocomponent polypropylene filaments with a fibre diameter of 13-25 μm were produced and subsequently collected on a moving belt. The batt was produced on REICOFIL 3.1 technology from for beams. The nonwoven batt was fully bonded by a pair of heated rollers, where one roller had raised Pattern2(FIG.7). The temperature of the calender rollers (smooth roller/patterned roller) was 150° C./155° C. and the pressure was 75 N/mm. The resulting nonwoven web had material properties as shown in Table 2.

Example 4

The same nonwoven web was formed as described in Comparative Example 4, but with an additional step of hydro-patterning. The hydro-patterning was achieved with two drums, with the last drum in the line providing the web with apertures. The first drum had a wire mesh screen and one injector at the drum applying a water pressure of 200 bar to hydrotreat the web before aperturing at the second drum. The one injector at the first drum had two strips of holes, with the holes within each strip spaced a distance of 1.2 mm from one another. The second drum had a screen with an A1 pattern of pins (pins spaced a distance of 4.5 mm from one another) as described herein. Three injectors applying water pressure of 220 bar, 220 bar and 250 bar, respectively, were used to hydro-pattern the web with a pattern of apertures by forcing the web down onto the pins. The three injectors at the second drum each had two strips of holes, with the holes within each strip spaced a distance of 0.6 mm from one another. The aperturing process of Example 4 is summarized in Table 3. The resulting nonwoven web had material properties as shown in Table 2.

Comparative Example 5 (Precursor Web to Example 5)

A 25 gsm spunmelt type nonwoven batt was produced online in a continuous process from a mixture of polypropylene (type 3155E5 from Exxon) with color additive (SCC 91056 from Standridge Color Corporation), where monocomponent polypropylene filaments with a fiber diameter of 13-25 μm were produced and subsequently collected on a moving belt. The batt was produced on REICOFIL 3.1 technology from four spunbond beams. The nonwoven batt was fully bonded by a pair of heated rollers, where one roller had raised Pattern1(FIG.6). The temperature of the calender rollers (smooth roller/patterned roller) was 160° C./162° C. and the bonding pressure was 75 N/mm. The resulting nonwoven web had material properties as shown in Table 2.

Example 5

The same nonwoven web was formed as described in Comparative Example 5, but with an additional step of hydro-patterning. The hydro-patterning was achieved with two drums, with the last drum in the line providing the web with apertures. The first drum had a wire mesh screen and one injector at the drum applying a water pressure of 200 bar to hydrotreat the web before aperturing at the second drum. The one injector at the first drum had two strips of holes, with the holes within each strip spaced a distance of 1.2 mm from one another. The second drum had a screen with an A1 pattern of pins (pins spaced a distance of 4.5 mm from one another) as described herein. Three injectors applying water pressure of 220 bar, 220 bar and 250 bar, respectively, were used to hydro-pattern the web with a pattern of apertures by forcing the web down onto the pins. The three injectors at the second drum each had two strips of holes, with the holes within each strip spaced a distance of 0.6 mm from one another. The aperturing process of Example 5 is summarized in Table 3. The resulting nonwoven web had material properties as shown in Table 2.

Comparative Example 6 (Precursor Web to Example 6)

A 25 gsm spunmelt type nonwoven batt was produced online in a continuous process from a mixture of polypropylene (Mosten NB425 from Unipetrol) and copolymer (Vistamaxx 6102 from Exxon) in the weight ratio 75:15, color additive (SCC 91056 from Standridge Color Corporation) and soft enhancing additive based on erucamide (CESA-slip PP 42161 from Avient), where monocomponent polypropylene filaments with a fibre diameter of 13-25 μm were produced and subsequently collected on a moving belt. The batt was produced on REICOFIL 3.1 technology from four beams. The nonwoven batt was fully bonded by a pair of heated rollers, where one roller had raised Pattern1(FIG.6). The temperature of the calender rollers (smooth roller/patterned roller) was 150° C./155° C. and the bonding pressure was 75 N/mm. The resulting nonwoven web had material properties as shown in Table 2.

Example 6

The same nonwoven web was formed as described in Comparative Example 6, but with an additional step of hydro-patterning. The hydro-patterning was achieved with two drums, with the last drum in the line providing the web with apertures. The first drum had a wire mesh screen and one injector at the drum applying a water pressure of 200 bar to hydrotreat the web before aperturing at the second drum. The one injector at the first drum had two rows of holes, with the holes within each strip spaced a distance of 1.2 mm from one another. The second drum had a screen with an A1 pattern of pins (pins spaced a distance of 4.5 mm from one another) as described herein. Three injectors applying water pressure of 220 bar, 220 bar and 250 bar, respectively, were used to hydro-pattern the web with a pattern of apertures by forcing the web down onto the pins. The three injectors at the second drum each had two strips of holes, with the holes within each strip spaced a distance of 0.6 mm from one another. The aperturing process of Example 6 is summarized in Table 3. The resulting nonwoven web had material properties as shown in Table 2.

TABLE 2COMPARATIVE EXAMPLE(precursor web)EXAMPLE123456123456MDT, N/cm9.29.87.99.013.49.06.97.54.32.36.44.3MDE, Peak, %557741677454676952755446CDT, N/cm5.35.54.93.96.94.93.24.21.56.32.92.5CDE, Peak, %718967798761688565636565MD HOM, g6.34.55.84.68.05.16.25.75.58.63.9CD HOM, g2.71.82.01.23.42.43.63.12.35.32.4Avg HOM, g4.53.13.92.95.73.74.94.43.97.03.2Thickness, mm0.200.170.210.180.180.170.510.370.470.390.460.37Kinetic CoF side A0.350.380.350.380.320.370.700.490.450.620.47Kinetic CoF side B0.350.380.350.380.320.370.700.490.450.620.47Abrasion data A55255552.5555sideAbrasion data B55255552.5555sideVisual Clarityn/an/an/an/an/an/a334343

TABLE 3PATTERNHYDRO-PATTERNINGofLINEDRUM 1DRUM 2precursorSPEEDINJ1PinINJ1INJ2INJ3Energy fluxweb(mpm)STRIP(bar)STRIPpattern(bar)(bar)(bar)(kWh/kg)EXAMPLE 13 (S)2002j122002j6A12202202500.6EXAMPLE 23 (S)2002j122002j6A12202202500.6EXAMPLE 32 (lines)2002j122002j6A12202202500.6EXAMPLE 42 (lines)2002j122002j6A12202202500.6EXAMPLE 51 (Oval)2002j122002j6A12202202500.6EXAMPLE 61 (Oval)2002j122002j6A12202202500.6

Comparative Example 7 (Precursor Web to Example 7)

A 35 gsm spunmelt type nonwoven batt was produced online in a continuous process from a mixture of polypropylene (type 3155E5 from Exxon) with color additive (SCC 91056 from Standridge Color Corporation), where monocomponent polypropylene filaments with a fiber diameter of 13-25 μm were produced and subsequently collected on a moving belt. The batt was produced on REICOFIL 5 technology from three spunbond beams. The nonwoven batt was fully bonded by a pair of heated rollers, where one roller had raised Pattern3(FIG.8). The temperature of the calender rollers (smooth roller/patterned roller) was 160° C./162° C. and the bonding pressure was 75 N/mm. The resulting nonwoven web had material properties as shown in Table 4.

Example 7

The same nonwoven web was formed as described in Comparative Example 7, but with an additional step of hydro-patterning. The hydro-patterning was achieved with two drums, with the last drum in the line providing the web with apertures. The first drum had a wire mesh screen and one injector at the drum applying a water pressure of 150 bar to hydrotreat the web before aperturing at the second drum. The one injector at the first drum had two rows of holes, with the holes within each strip spaced a distance of 1.2 mm from one another. The second drum had a screen with an Q5 pattern of pins (hearts) as described herein. Three injectors applying water pressure of 220 bar, 220 bar and 250 bar, respectively, were used to hydro-pattern the web with a pattern of apertures by forcing the web down onto the pins. The three injectors at the second drum each had two strips of holes, with the holes within each strip spaced a distance of 0.6 mm from one another. The aperturing process of Example 7 is summarized in Table 5. The resulting nonwoven web had material properties as shown in Table 4.

Comparative Example 8 (Precursor Web to Example 8)

A 25 gsm spunmelt type nonwoven batt was produced online in a continuous process from a mixture of polypropylene (Mosten NB425 from Unipetrol) with color additive (SCC 91056 from Standridge Color Corporation), where monocomponent polypropylene filaments with a fiber diameter of 13-25 μm were produced and subsequently collected on a moving belt. The batt was produced on REICOFIL 4 technology from three spunbond beams. The nonwoven batt was fully bonded by a pair of heated rollers, where one roller had raised Pattern1(FIG.6). The temperature of the calender rollers (smooth roller/patterned roller) was 160° C./162° C. and the bonding pressure was 75 N/mm. The resulting nonwoven web had material properties as shown in Table 4.

Example 8

The same nonwoven web was formed as described in Comparative Example 8, but with an additional step of hydro-patterning. The hydro-patterning was achieved with two drums, with the last drum in the line providing the web with apertures. The first drum had a wire mesh screen and one injector at the drum applying a water pressure of 150 bar to hydrotreat the web before aperturing at the second drum. The one injector at the first drum had two rows of holes, with the holes within each strip spaced a distance of 1.2 mm from one another. The second drum had a screen with an Q5 pattern of pins (hearts) as described herein. Three injectors applying water pressure of 220 bar, 220 bar and 250 bar, respectively, were used to hydro-pattern the web with a pattern of apertures by forcing the web down onto the pins. The three injectors at the second drum each had two strips of holes, with the holes within each strip spaced a distance of 0.6 mm from one another. The aperturing process of Example 8 is summarized in Table 5. The resulting nonwoven web had material properties as shown in Table 4.

Comparative Example 9 (Precursor Web to Example 9)

A 25 gsm spunmelt type nonwoven batt was produced online in a continuous process from a mixture of polypropylene (Mosten NB425 from Unipetrol) with color additive (SCC 91056 from Standridge Color Corporation), where monocomponent polypropylene filaments with a fiber diameter of 13-25 μm were produced and subsequently collected on a moving belt. The batt was produced on REICOFIL 4 technology from three spunbond beams. The nonwoven batt was fully bonded by a pair of heated rollers, where one roller had raised Pattern3(FIG.8). The temperature of the calender rollers (smooth roller/patterned roller) was 160° C./162° C. and the bonding pressure was 75 N/mm. The resulting nonwoven web had material properties as shown in Table 4.

Example 9

The same nonwoven web was formed as described in Comparative Example 9, but with an additional step of hydro-patterning. The hydro-patterning was achieved with two drums, with the last drum in the line providing the web with apertures. The first drum had a wire mesh screen and one injector at the drum applying a water pressure of 150 bar to hydrotreat the web before aperturing at the second drum. The one injector at the first drum had two rows of holes, with the holes within each strip spaced a distance of 1.2 mm from one another. The second drum had a screen with an Q5 pattern of pins (hearts) as described herein. Three injectors applying water pressure of 220 bar, 220 bar and 250 bar, respectively, were used to hydro-pattern the web with a pattern of apertures by forcing the web down onto the pins. The three injectors at the second drum each had two strips of holes, with the holes within each strip spaced a distance of 0.6 mm from one another. The aperturing process of Example 9 is summarized in Table 5. The resulting nonwoven web had material properties as shown in Table 4.

Comparative Example 10 (Precursor Web to Example 10)

A 30 gsm spunmelt type nonwoven batt was produced online in a continuous process from bicomponent filaments of core/sheath type with a ratio of 80:20. The core was formed of aliphatic polyester (PLA Ingeo 6100D from Nature Works) and the sheath was formed of aliphatic polyester with lower melting point and crystallinity (PLA ingeo 6752 s from Nature Works) with slip additive (Avient CR Bio 2144 from Avient). Bicomponent filaments with a fiber diameter of 15-30 μm were produced and subsequently collected on a moving belt. The batt was produced on REICOFIL 4 technology from one spunbond beam. The nonwoven batt was fully bonded by a pair of heated rollers, where one roller had raised Pattern1(FIG.6). The temperature of the calender rollers (smooth roller/patterned roller) was 140° C./138° C. and the bonding pressure was 50 N/mm. The resulting nonwoven web had material properties as shown in Table 4.

Example 10

The same nonwoven web was formed as described in Comparative Example 10, but with an additional step of hydro-patterning. The hydro-patterning was achieved with two drums, with the last drum in the line providing the web with apertures. The first drum had a wire mesh screen and one injector at the drum applying a water pressure of 100 bar to hydrotreat the web before aperturing at the second drum. The one injector at the first drum had two rows of holes, with the holes within each strip spaced a distance of 1.2 mm from one another. The second drum had a screen with an Q5 pattern of pins (hearts) as described herein. Three injectors applying water pressure of 110 bar, 110 bar and 120 bar, respectively, were used to hydro-pattern the web with a pattern of apertures by forcing the web down onto the pins. The three injectors at the second drum each had two strips of holes, with the holes within each strip spaced a distance of 0.6 mm from one another. The aperturing process of Example 9 is summarized in Table 5. The resulting nonwoven web had material properties as shown in Table 4.

TABLE 4COMPARATIVE EXAMPLE(precursor web)EXAMPLE7891078910MDT, N/cm11.57.79.11910.75.898.576.21MDE, Peak, %4237451066465814CDT, N/cm6.855.55.67.15.993.113.593.1CDE, Peak, %51779133817010154MD HOM, g12.64.75.130135.325.411.3CD HOM, g52.1215.66.262.161.754.16Avg HOM, g8.83.43.5522.89.633.743.5757.73Thickness, mm0.390.220.210.370.750.570.510.63Kinetic CoF side A0.310.330.350.410.610.680.740.78Kinetic CoF side B0.30.320.330.410.650.640.660.75Abrasion data A5554.55553.8sideAbrasion data B5554.75554sideVisual Clarityn/an/an/an/a4445

TABLE 5PATTERNHYDRO-PATTERNINGofLINEDRUM 1DRUM 2precursorSPEEDINJ1PinINJ1INJ2INJ3Energy fluxweb(mpm)STRIP(bar)STRIPpattern(bar)(bar)(bar)(kWh/kg)EXAMPLE 73 (S)1002j122001j6, 1j6, 2j6Q52202202501.4EXAMPLE 81 (oval)1002j122001j6, 1j6, 2j6Q52202202501.9EXAMPLE 93 (S)1002j122001j6, 1j6, 2j6Q52202202501.9EXAMPLE 101 (oval)1002j121001j6, 1j6, 2j6Q51101101200.6

As observed from Table 2, each nonwoven webs as described in Examples 1 through 6 is improved as compared to its corresponding Comparative Example in terms of thickness, with an average increase of at least 100%. It is also important to note that the COF of each nonwoven web as described in Examples 1 through 6 is significantly higher than that of its corresponding Comparative Example. Higher COF is generally preferred by converters such as diaper manufacturers as it prevents diaper to diaper slippage, especially when the diapers are tightly packed to fit multiple diapers in a single pack. Although the tensile strength of each nonwoven as described in Examples 1 through 6 is lower than that of its corresponding Comparative Example, it is important to note that the hydro-patterned nonwoven webs described in Examples 1 through 6 each provide a hygiene product manufacturer with a unique fabric that meets typical product strength requirements and excellent abrasion resistance while providing a visually distinct (apertured) fabric and higher thickness. The visual clarity is a function of the fiber modulus, resulting from its composition and/or additives, combined with the bond pattern and pin geometry used to calender bond the precursor web. Hydro-apertured samples with the best visual clarity and abrasion performance were the result of fibers without softening additives and thermal bond patterns that overlayed with minimal conflict with the aperturing drum design to allow for the creation of apertures via the movement of the fibers. This is demonstrated by Example 3 which had the lowest abrasion performance, but good visual clarity while Example 5 had similar visual clarity but superior abrasion performance due to the difference in the calender bonding geometries.

It should be noted that tensile strength drop of the web during hydraulic treatments is not always the key parameter to evaluate. The tensile drop in the case of polyolefin based fabric typically needs to be as small as possible to fulfill requirements of convertors and final products. In contrast, Example 10 presents polyester-based fabric with rather high tensile strength. PLA based nonwovens typically have higher tensile strength, lower elongation and also higher HOM values. Hydraulic treatment of PLA based nonwovens according to the invention might cause a relatively higher drop in tensile strength (−67% in MD and −56% in CD) to values similar to polyolefin-based fabrics. But what is more important, softness indicators (especially HOM) also dropped to values much closer to polyolefin desired levels (AVG HOM from 22,8 to 7,8), and even the apertured fabric provided higher thickness comparing to the precursor (thicker fabric provides in general results in higher HOM values). Also, abrasion resistance remained high (close to 4 after hydraulic treatment) and visual clarity was perfect.

While in the foregoing specification a detailed description of specific embodiments of the invention was set forth, it will be understood that many of the details herein given may be varied considerably by those skilled in the art without departing from the spirit and scope of the invention.

Test Methods

The “tensile strength” and “elongation” of a nonwoven fabric was measured using testing methodology according to WSP 110.4.R4 (12) standard. Tensile strength can be expressed also as “MDT” for MD direction and “CDT” for CD direction. Accordingly, elongation can be also expressed as “MDE” for MD direction and “CDE” for CD direction.

The “Handle-O-Meter” or “HOM” stiffness test of nonwoven materials was performed in accordance with WSP test method 90.3 with a slight modification. The quality of “hand” is considered to be the combination of resistance due to the surface friction and flexural rigidity of a sheet material. The equipment used for this test method is available from Thwing Albert Instrument Co. In this test method, a 100×100 mm sample was used for the HOM measurement and the final readings obtained were reported “as is” in grams instead of doubling the readings per the WSP test method 90.3. Average HOM was obtained by taking the average of MD and CD HOM values. Typically, the lower the HOM values, the higher the softness and flexibility, while the higher HOM values means lower softness and flexibility of the nonwoven fabric.

“Thickness” or “measured height” or “caliper” of a nonwoven material was determined by means of a testing measurement methodology pursuant to European norm EN ISO 9073-2:1995 (corresponds to methodology WSP 120.6), which is modified in the following manner:

1. The material is to be measured by using a sample that is taken from production without being subjected to higher deformation forces or without being subjected to the effect of pressure for longer than a day (for example by the pressure exerted by the roller on the production equipment), whilst otherwise the material must be left for at least 24 hours laying freely on a surface.

2. The total pressure applied for the thickness measurement is 14.7 g/cm2.

3. When the fabric provides differences in thickness between edges of the apertures and the nonwoven itself, the value of the nonwoven between apertures shall be taken as the measured value.

“Kinetic coefficient of friction” or “kinetic CoF” of a nonwoven material was determined by using testing Machines Inc. 32-07 Series Friction Tester by means of the ASTM D 1894 standard. The reported data represents the nonwoven-to-nonwoven Kinetic Coefficient of Friction (CoF) on a 10 cm by 10 cm nonwoven sample placed under a 200 g sled which is pulled across a 25 cm×10 cm clamped sample of the same nonwoven, maintaining sidedness and orientation consistency (side A to side A; MD direction to MD direction), at a speed of 150 mm/min.

“Visual clarity” was determined visually by the naked eye by at least five people independently according to an Aperture Clarity Visual Ranking Scale (seeFIG.16). At least three people from the five (or alternatively at least ⅗ of the evaluation group) need to have the same evaluation on each fabric in order for the evaluation to be recorded. The individual valuations that are not consistent with the other at least three evaluations are not counted.

“Martindale Average Abrasion Resistance Grade Test” or “Martindale”

FIG.17is a perspective view of equipment for the Martindale Average Abrasion Resistance Grade Test. Specifically,FIG.17shows a grade scale for fuzz assessment in the Martindale Average Abrasion Resistance Grade Test.

Martindale Average Abrasion Resistance Grade of a nonwoven is measured using a Martindale Abrasion Tester. The test is conducted dry.

Nonwoven samples are conditioned for 24 hours at 23±2° C. and at 50±2% relative humidity.

From each nonwoven sample, cut 10 circular samples 162 mm (6.375 inches) in diameter. Cut a piece of Standard Felt into a circle of 140 mm in diameter.

Secure each sample on each testing abrading table position of the Martindale by first placing the cut felt, then the cut nonwoven sample. Then secure the clamping ring, so no wrinkles are visible on the nonwoven sample.

Assemble the abradant holder. The abradant is a 38 mm diameter FDA compliant silicone rubber 1/32 inch thick (obtained from McMaster Carr, Item 86045K21-50A). Place the required weight in the abradant holder to apply 9 kPa pressure to the sample. Place the assembled abradant holder in the Model #864 such that the abradant contacts the NW sample as directed in the Operator's Guide.

Operate the Martindale abrasion under conditions below:

Mode: Abrasion Test

Speed: 47.5 cycles per minute; and

Cycles: 80 cycles

After the test stops, place the abraded nonwoven on a smooth, matte, black surface and grade its fuzz level using the scale provided inFIG.17. Each sample is evaluated by observing both from the top, to determine dimension and number of defects, and from the side, to determine the height of the loft of the defects. A number from 5 to 1 is assigned based on the best match with the grading scale. The Martindale Average Abrasion Resistance Grade is then calculated as the average rating of all samples and reported to nearest tenth.

“Bond Area Percentage” is determined using ImageJ software (Vs. 1.43u, National Institutes of Health, USA) by identifying a single repeat pattern of bond impressions and unbonded areas and enlarging the image such that the repeat pattern fills the field of view. In ImageJ draw a box that encompasses the repeat pattern. Calculate area of the box and record to the nearest 0.01 mm2. Next, with the area tool, trace the individual bond impressions or portions thereof entirely within the box and calculate the areas of all bond impressions or portions thereof that are within the box. Record to the nearest 0.01 mm2. Calculate as follows:
Percent Bond Area=(Sum of areas of bond impressions within box)/(area of box)×100%

Repeat for a total of five non-adjacent ROI's randomly selected across the total specimen. Record as Percent Bond Area to the nearest 0.01%. Measurements are made on both specimens from each article. A total of three identical articles are measured for each sample set. Calculate the average and standard deviation of all 30 of the percent bond area measurements and report to the nearest 0.001 units.