Porous hydro-patterned nonwoven fabric and method for manufacturing the same

Abstract

A method for forming a porous hydropatterned nonwoven fabric, comprising: forming a nonwoven batt of continuous spunmelt fibers; calendaring the nonwoven batt to form a fully bonded precursor nonwoven fabric having a regular bonded pattern defining individual bonded impressions and non-bonded areas between the individual bonded impressions, the regular bonded pattern having a bonded area percentage of 10% to 25%; and hydraulically imparting a plurality of holes into the fully bonded precursor nonwoven fabric, the method comprising hydrostatically treating the fully bonded precursor nonwoven fabric with multiple water jets as the fully bonded precursor nonwoven fabric passes over a plurality of pins.

Description

Technical Field

[0001] Cross-reference of related applications This application claims priority and the benefit of U.S. Provisional Application No. 63 / 183,190, filed on May 3, 2021, entitled "APERTURED HYDRO-PATTERNED NONWOVEN AND METHOD OF MAKING THE SAME", the contents of which are incorporated herein by reference in their entirety.

[0002] The present invention relates to a porous nonwoven fabric and an improved method for manufacturing the porous nonwoven fabric, in which an adhesive pattern is applied to the nonwoven fabric before subjecting it to a hydrostatic treatment to form holes in the nonwoven fabric.

Background Art

[0003] Spunmelt nonwoven fabrics (e.g., spunbond nonwoven fabrics, meltblown nonwoven fabrics, or combinations thereof) are formed from thermoplastic continuous fibers such as polypropylene (PP), polyethylene terephthalate (PET), bicomponent or multicomponent fibers, and mixed fibers of such spunmelt fibers and rayon, cotton, and cellulosic pulp fibers. Conventionally, spunmelt nonwoven fabrics are subjected to thermal bonding, ultrasonic bonding, chemical bonding (e.g., bonding with latex), or resin bonding, etc., and the bonding hardly collapses and does not change even by subsequent processing and conversion. Thermal bonding and ultrasonic bonding result in permanent fusion, while chemical bonding may or may not be permanent.

[0004] It is well known that hydrostatic treatment can be applied to improve fabric properties such as flexibility and bulkiness. For example, U.S. Patent No. 7,858,544 describes one known hydrostatic treatment process called hydroengorgement. It is also well known that multiple pores can be formed in nonwoven fabrics by many methods using different technical processes. Such processes include heating (e.g., over-bonding, hot needles, or hot pins) or hydrostatic treatment using different types of screens (e.g., by pressing the fabric into or around pins / projections), as described in U.S. Patents No. 7,455,800; No. 7,091,140; No. 6,321,425; No. 6,903,034; and No. 4,886,632. The pore patterns formed by hydraulic treatment are generally created on low-adhesion fabrics by performing multiple water jetting steps on corresponding screens having a predetermined pore pattern, as described, for example, in U.S. Patent No. 10,737,459. In the case of spunmelt fabrics, calendering is used to impart most of the fabric's mechanical properties, followed by hydraulic treatment, which can promote flexibility and potentially form pores.

[0005] However, because a low level of adhesion is required, the final stability and tensile strength of the fabric are limited. Past attempts to use hydrostatic pore formation technology on more highly bonded fabrics have not yielded satisfactory results in terms of pore clarity, and therefore it has been difficult to achieve desirable fabric quality levels, such as flexibility and strength, using such technology.

[0006] Therefore, there is a need for a method to produce porous nonwoven fabrics from fully bonded precursor fabrics that yields products with a good combination of properties such as pore clarity, flexibility, abrasion resistance, and tensile strength.

[0007] Summary of the Invention A method for forming a porous hydro-patterned nonwoven fabric according to an exemplary embodiment of the present invention: a step of forming a nonwoven vat made of continuous spunmelt fibers; A step of forming a fully bonded precursor nonwoven fabric having a regular bonding pattern that defines individual bonding impressions and non-bonded areas between individual bonding impressions, wherein the bonding area of ​​the regular bonding pattern is 10% to 25% in percentage; and a step of imparting a plurality of holes to the fully bonded precursor nonwoven fabric by water pressure, wherein the fully bonded precursor nonwoven fabric is subjected to water pressure treatment by water spraying in a plurality of steps as the fully bonded precursor nonwoven fabric passes over a plurality of pins.

[0008] A method for forming a porous hydro-patterned nonwoven fabric according to an exemplary embodiment of the present invention includes: forming a nonwoven batt made of continuous spunmelt fibers; calendering the nonwoven batt to define individual adhesive indentations and non-adherent areas between individual adhesive indentations to form a fully bonded precursor nonwoven fabric having a regular adhesive pattern in which the adhesive areas account for 10% to 25% of the total area; and imparting a plurality of pores to the fully bonded precursor nonwoven fabric by hydrostatic pressure, the method comprising hydrostatic treatment of the fully bonded precursor nonwoven fabric by pressing the calendering-bonded precursor nonwoven fabric against a plurality of pins using the hydrostatic pressure of a water spraying device.

[0009] In exemplary embodiments, each pin has a base and a top, the area of ​​the base is greater than the area of ​​the top.

[0010] In exemplary embodiments, each of the pins is symmetrical with respect to its major axis.

[0011] In an exemplary embodiment, each pin has a base, and the distance between the centers of directly adjacent pins is at least 100%, preferably 150%, of the diameter of the base.

[0012] In an exemplary embodiment, the height of the pins is at least 100% of the thickness of the porous nonwoven fabric, preferably at least 115%, and more preferably at least 130%.

[0013] In an exemplary embodiment, the height of the pin is at least 200% of the thickness of the precursor fabric, preferably at least 250%, and more preferably at least 300% of the thickness of the precursor fabric.

[0014] In an exemplary embodiment, the pins are positioned on a surface that moves at approximately the same speed as the calendar-adhering precursor nonwoven fabric.

[0015] In exemplary embodiments, each pin differs in size and / or shape, is arranged on a screen or belt, and the distance between the centers of directly adjacent pins is at least 100% of the maximum base diameter of the pin, preferably at least 150% of the maximum base diameter of the pin.

[0016] In an exemplary embodiment, in the step of forming the precursor fabric, the spunmelt fibers of the nonwoven batt consist of spunbond filaments.

[0017] In an exemplary embodiment, in the step of forming the precursor fabric, the nonwoven batt consists of two or more layers.

[0018] In an exemplary embodiment, in the step of forming the precursor fabric, the spunmelt fibers in each of the two or more layers consist of spunbond filaments.

[0019] In an exemplary embodiment, in the step of forming the preliminary fabric, the average difference in fiber thickness between the layers is less than 20%, preferably less than 15%, more preferably less than 10%, and even more preferably less than 5%.

[0020] In an exemplary embodiment, the process of forming the precursor fabric involves at least one of two or more layers consisting of spunbond filaments and at least one of the other two or more layers consisting of meltblown fibers.

[0021] In an exemplary embodiment, in the step of forming the precursor fabric, at least one layer composed of the spunbond filaments forms at least one outer layer of the nonwoven bat.

[0022] In an exemplary embodiment, in the step of forming the precursor fabric, the nonwoven bat is composed of three or more layers, and the three or more layers form a spunbond-meltblown-spunbond (SMS) structure.

[0023] In an exemplary embodiment, before the hydrostatic pressure treatment step, the method further includes the step of applying at least one layer formed from fibers and / or particles to the fully bonded nonwoven precursor fabric.

[0024] In an exemplary embodiment, the fibers are short synthetic fibers, preferably polyester staple fibers or viscose fibers.

[0025] In an exemplary embodiment, the fibers are natural fibers, preferably cotton fibers or pulp, or modified cellulose such as rayon.

[0026] In an exemplary embodiment, in the step of forming the precursor fabric, the continuous spunmelt fibers are single-component fibers formed from a thermoplastic polymer, preferably a polyolefin or polyester or polyamide-based homopolymer, a copolymer of a polymer blend.

[0027] In an exemplary embodiment, in the step of forming the precursor fabric, the continuous spunmelt fibers are multi-component, preferably two-component fibers, and each component is formed from a thermoplastic polymer, preferably a polyolefin or polyester or polyamide-based homopolymer, a copolymer of a polymer blend.

[0028] In an exemplary embodiment, at least 40% of the surface of each filament, preferably at least 50% of the surface of each filament, more preferably at least 60% of the surface of each filament, and even more preferably the entire surface of each filament, the melting point of the component polymer composition is lower than the melting point of at least one other component polymer composition, preferably at least 2 °C lower, more preferably at least 5 °C lower.

[0029] In an exemplary embodiment, in the step of forming the precursor fabric, the continuous spunmelt fibers are composed of polyolefin, or polyamide, or polyester, or polysaccharide homopolymer, copolymer, or polymer blend.

[0030] In an exemplary embodiment, in the step of forming the precursor fabric, the continuous spunmelt fibers are composed of polypropylene, polyethylene, polylactic acid, polyhydroxyalkanoate, polyhydroxybutyrate, polybutylene succinate, polyethylene terephthalate, thermoplastic starch, copolymers thereof, olefins, esters, amides or copolymers thereof with other polymers, or blends thereof.

[0031] In an exemplary embodiment, in the step of forming the precursor fabric, the continuous spunmelt fibers are bicomponent core - sheath fibers having a core made of polypropylene and a sheath made of a blend of polypropylene and copolymer polypropylene - polyethylene.

[0032] In an exemplary embodiment, in the step of forming the precursor fabric, the continuous spunmelt fibers contain additives.

[0033] In an exemplary embodiment, the additives include additives of a type selected from the group consisting of coloring pigments, softening accelerators, lubricants, fillers, and combinations thereof.

[0034] In an exemplary embodiment, the step of forming the precursor fabric includes forming adhesive indentations having an adhesive shape.

[0035] In exemplary embodiments, the adhesive indentation may have a first dimension or be formed from an adhesive point or dot having a second dimension, the second dimension being smaller than the first dimension.

[0036] In an exemplary embodiment, the adhesive shape is oriented such that the maximum measurable length exists along a line intersecting the outer edge of the adhesive shape, and it intersects with an axis on the surface along the machine direction to form an angle αT of 0 to 65 degrees.

[0037] In an exemplary embodiment, the adhesive shape includes a protrusion.

[0038] In an exemplary embodiment, the adhesive shape includes a recess.

[0039] In an exemplary embodiment, the adhesive shape includes at least one of a convex portion and a concave portion.

[0040] In an exemplary embodiment, the adhesive shape is asymmetrical.

[0041] In an exemplary embodiment, the step of forming the preliminary fabric includes the step of forming adhesive indentations in the quilting pattern.

[0042] In an exemplary embodiment, the adhesive shape of the adhesive indentation is elliptical.

[0043] In an exemplary embodiment, the adhesive shape of the adhesive indentation is linear.

[0044] In an exemplary embodiment, the adhesive shape of the adhesive indentation has an outer edge of the adhesive shape having a maximum measurable length and a maximum measurable width.

[0045] In exemplary embodiments, the aspect ratio of the maximum measurable length to the maximum measurable width is at least 1.0, preferably at least 1.5, more preferably at least 2.0, and even more preferably at least 2.5.

[0046] In an exemplary embodiment, the fully bonded nonwoven precursor fabric contains at least 20, preferably at least 40, more preferably at least 50, and even more preferably at least 60 adhesive indentations per square centimeter.

[0047] In an exemplary embodiment, the maximum measurable length exists along the adhesive indentation line intersecting the outer edge of the adhesive shape, and intersects with an axis on the surface along the machine direction to form an angle αT of 20 to 80 degrees, preferably 40 to 80 degrees, and more preferably 50 to 70 degrees.

[0048] In an exemplary embodiment, the step of forming the precursor fabric includes the step of forming a fully bonded nonwoven precursor fabric having fewer than 20 adhesive indentations per square centimeter, preferably fewer than 15 per square centimeter, and more preferably fewer than 5 per square centimeter.

[0049] In exemplary embodiments, the adhesive shape of the adhesive indentation has an outer edge of the adhesive shape having a maximum measurable length and a maximum measurable width, and the aspect ratio of the maximum measurable length to the maximum measurable width is at least 2.0, more preferably 2.5, and even more preferably at least 3.

[0050] In an exemplary embodiment, the adhesive shape is linear.

[0051] In an exemplary embodiment, the adhesive shape is S-shaped.

[0052] In an exemplary embodiment, the adhesive shape of the adhesive indentation has an outer edge of the adhesive shape having a maximum measurable length and a maximum measurable width, the maximum measurable length exists along the adhesive indentation line intersecting the outer edge of the adhesive shape, and intersects with an axis on the surface along the machine direction to form an angle αT of 5 to 15 degrees, preferably 8 to 12 degrees, and more preferably 9 to 11 degrees.

[0053] In an exemplary embodiment, the step of forming the preliminary fabric includes forming adhesive indentations in the form of a quilting pattern.

[0054] In an exemplary embodiment, the adhesive indentation of the quilting pattern has quilting pattern lines that intersect with a virtual line extending in the machine direction to form an angle αTq of 5 to 60 degrees, preferably 10 to 50 degrees, and more preferably 15 to 40 degrees.

[0055] In an exemplary embodiment, the MD-direction HOM value of the precursor nonwoven fabric is at least 5 g.

[0056] In an exemplary embodiment, the CD-direction HOM value of the precursor nonwoven fabric is at least 2g.

[0057] In an exemplary embodiment, the MD-direction HOM value of the precursor nonwoven fabric is 30g or less, preferably 25g or less.

[0058] In an exemplary embodiment, the CD-direction HOM value of the precursor nonwoven fabric is 20g or less, preferably 15g or less.

[0059] In exemplary embodiments, the basis weight of the precursor nonwoven fabric is at least 5 gsm, preferably at least 10 gsm, preferably at least 15 gsm, and more preferably at least 20 gsm or less.

[0060] In an exemplary embodiment, the basis weight of the precursor nonwoven fabric is 60 gsm or less, preferably 50 gsm or less, more preferably 45 gsm or less, and even more preferably 35 gsm or less.

[0061] In an exemplary embodiment, the hydraulic treatment step includes applying water pressure to the nonwoven precursor fabric using a water jetting device.

[0062] In an exemplary embodiment, the water pressure applied to the precursor fabric is expressed as an energy flux of at least 0.2 kWh / kg, preferably 0.3 kWh / kg.

[0063] In an exemplary embodiment, the water pressure applied to the precursor fabric is expressed as an energy flux of 1.9 kWh / kg or less, preferably 3.0 kWh / kg or less.

[0064] In an exemplary embodiment, the hydraulic treatment step includes applying water pressure to the nonwoven precursor fabric using at least two water jetting devices.

[0065] In an exemplary embodiment, the method is carried out at a line speed of at least 150 m / min.

[0066] In an exemplary embodiment, the line speed is 450 m / min or less.

[0067] In an exemplary embodiment, the hydraulic treatment step includes applying water pressure to the nonwoven precursor fabric using four sets of water jets, each set of water jets applying a water pressure of 150 bar or more.

[0068] In an exemplary embodiment, the hydraulic treatment step includes applying water pressure to the nonwoven precursor fabric by three sets of water jets, each set of water jets applying a higher water pressure than that applied by the set of water jets preceding it in the machine direction.

[0069] In an exemplary embodiment, the three sets of water jets comprise a first set of water jets, a second set of water jets preceding the first set of water jets in the mechanical direction, and a third set of water jets preceding the first and second sets of water jets in the mechanical direction, wherein the second set of water jets applies a water pressure of 80% to 95% of the water pressure applied by the first set of water jets, and the third set of water jets applies a water pressure of 64% to 90% of the water pressure applied by the second set of water jets.

[0070] In an exemplary embodiment, the hydraulic treatment step includes applying water pressure to the nonwoven precursor fabric using three sets of water jetting devices, each water jetting device applying a water pressure of 200 bar or more.

[0071] In an exemplary embodiment, the hydraulic treatment step includes applying water pressure to the nonwoven precursor fabric using two sets of water jetting devices, each water jetting device applying a water pressure of 300 bar or more.

[0072] In an exemplary embodiment, the hydraulic treatment step involves applying a water jet to the calender-bonding precursor nonwoven fabric at an angle of 80 to 100° with respect to the calender-bonding precursor nonwoven fabric.

[0073] In an exemplary embodiment, the step of imparting a plurality of holes to the fully bonded precursor nonwoven fabric by water pressure includes at least partially altering the individual adhesive indentations by applying water pressure.

[0074] In an exemplary embodiment, the at least partially altering step ensures that at least 60% of the fully bonded portion of each adhesive indentation remains after the step of applying water pressure.

[0075] In an exemplary embodiment, the at least partially altering step ensures that at least 70% of the fully bonded portion of each adhesive indentation remains after the step of applying water pressure.

[0076] In an exemplary embodiment, the at least partially altering step ensures that at least 80% of the fully bonded portion of each adhesive indentation remains after the step of applying water pressure.

[0077] In an exemplary embodiment, the at least partially altering step ensures that at least 90% of the fully bonded portion of each adhesive indentation remains after the step of applying water pressure.

[0078] In an exemplary embodiment, the at least partially altering step divides each of the adhesive indentations into at least two parts.

[0079] In an exemplary embodiment, the at least partially altering step causes the fibers in the region surrounding the outer edge of each adhesive indentation to fray randomly inside and outside the main plane of the fully bonded precursor nonwoven fabric, so that at least a portion of each adhesive indentation is no longer three-dimensional.

[0080] According to exemplary embodiments, the porous hydro-patterned nonwoven fabric is manufactured according to any of the processing steps described above.

[0081] In exemplary embodiments, the basis weight of the porous hydro-patterned nonwoven fabric is 60 gsm or less, preferably 50 gsm or less, more preferably 45 gsm or less, and even more preferably 35 gsm or less.

[0082] In an exemplary embodiment, the MD-direction tensile strength of the porous hydro-patterned nonwoven fabric is at least 4 N / cm.

[0083] In an exemplary embodiment, the tensile strength in the CD direction of the porous hydropatterned nonwoven fabric is at least 2 N / cm.

[0084] In an exemplary embodiment, the caliper of the porous hydro-patterned nonwoven fabric is at least 12 microns / 1 gsm of fabric.

[0085] In exemplary embodiments, the porous hydro-patterned nonwoven fabric is identical on both sides.

[0086] In exemplary embodiments, the porous hydro-patterned nonwoven fabric is visually indistinguishable on both sides, as can be seen with the naked eye.

[0087] In an exemplary embodiment, the porous hydro-patterned nonwoven fabric is identical on both sides in terms of wear evaluation.

[0088] In exemplary embodiments, the porous hydro-patterned nonwoven fabric is identical on both sides in terms of the coefficient of friction.

[0089] In an exemplary embodiment, the visual pore clarity of the porous hydro-patterned nonwoven fabric is at least 3 on an index of 1 to 5.

[0090] A method for forming a porous hydro-patterned nonwoven fabric according to an exemplary embodiment of the present invention comprises: a step of forming a fully bonded precursor nonwoven fabric having a regular bonding pattern that defines individual bonding impressions and non-bonding regions between individual bonding impressions, wherein the bonding area of ​​the regular bonding pattern is 10% to 25% in percentage; and a step of hydro-pressure treating the fully bonded precursor nonwoven fabric by water jetting in multiple steps as the fully bonded precursor nonwoven fabric passes over a plurality of pins, thereby forming a plurality of holes in the fully bonded precursor nonwoven fabric.

[0091] The above-mentioned related objects, features, and advantages of the present invention will be better understood by referring to the following detailed description of preferred but illustrative embodiments of the present invention, together with the accompanying drawings: [Brief explanation of the drawing]

[0092] [Figure 1] This is a representative diagram of a system for forming a patterned, hydrophobic nonwoven fabric according to an exemplary embodiment of the present invention; [Figure 2A] This is a representative diagram of a system for forming a patterned, hydrophobic nonwoven fabric according to another exemplary embodiment of the present invention; [Figure 2B] This is a representative diagram of a system for forming a patterned, hydrophobic nonwoven fabric according to another exemplary embodiment of the present invention; [Figure 3] This figure shows a pin with altered dimensions according to an exemplary embodiment of the present invention; [Figure 4] This figure shows adhesive indentations of varying dimensions according to an exemplary embodiment of the present invention; [Figure 5]This figure shows adhesive indentations of varying dimensions according to an exemplary embodiment of the present invention; [Figure 6] This shows an adhesive pattern usable in a method for forming a patterned, hydrophobic nonwoven fabric according to an exemplary embodiment of the present invention; [Figure 7] This shows an adhesive pattern usable in a method for forming a patterned, hydrophobic nonwoven fabric according to an exemplary embodiment of the present invention; [Figure 8] This shows an adhesive pattern usable in a method for forming a patterned, hydrophobic nonwoven fabric according to an exemplary embodiment of the present invention; [Figure 9] This shows an adhesive pattern usable in a method for forming a patterned, hydrophobic nonwoven fabric according to an exemplary embodiment of the present invention; [Figure 10] These are macroscopic and magnified views of a patterned, hydrophobic nonwoven fabric according to an exemplary embodiment of the present invention; [Figure 11] This is a plan view photograph of a patterned, hydrophobic nonwoven fabric according to an exemplary embodiment of the present invention; [Figure 12] This is a plan view photograph of a patterned, hydrophobic nonwoven fabric according to an exemplary embodiment of the present invention; [Figure 13] These are macroscopic and magnified views of both sides of a patterned, hydrophobic nonwoven fabric according to an exemplary embodiment of the present invention; [Figure 14] These are macroscopic and magnified views of both sides of a patterned, hydrophobic nonwoven fabric according to an exemplary embodiment of the present invention; [Figure 15] These are magnified views of both sides of a conventional porous nonwoven fabric; [Figure 16] This is an Aperture Clarity Visual Ranking Scale according to an exemplary embodiment of the present invention; [Figure 17] A perspective view of a grade measuring device for evaluating fuzziness in the Martindale mean abrasion resistance grade test; [Figure 18] This is the Martindale abrasion test grade index; [Figure 19A] The changes in individual adhesive indentations obtained from the process of an exemplary embodiment of the present invention are shown in cross-section; [Figure 19B] The changes in individual adhesive indentations obtained from the process of an exemplary embodiment of the present invention are shown in cross-section; [Figure 19C] The changes in individual adhesive indentations obtained from the process of an exemplary embodiment of the present invention are shown in cross-section; [Figure 19D] The changes in individual adhesive indentations obtained from the process of an exemplary embodiment of the present invention are shown in cross-section; [Figure 19E] This is a micrograph showing the cross-sectional changes in individual adhesive indentations obtained from a conventional hydraulic treatment process; [Figure 19F] This is a micrograph showing the cross-sectional changes in individual adhesive indentations obtained from a conventional hydraulic treatment process; [Figure 20A] This is a plan view photograph of a patterned, perforated nonwoven fabric manufactured according to Example 8 described herein; [Figure 20B] This is a plan view photograph of a patterned, perforated nonwoven fabric manufactured according to Example 8 described herein; [Figure 20C] This is a plan view photograph of a patterned, perforated nonwoven fabric manufactured according to Example 8 described herein; [Figure 21A] This is a plan view photograph of a patterned, perforated nonwoven fabric manufactured according to Example 9 described herein; [Figure 21B] This is a plan view photograph of a patterned, perforated nonwoven fabric manufactured according to Example 9 described herein; [Figure 21C] This is a plan view photograph of a patterned, perforated nonwoven fabric manufactured according to Example 9 described herein; [Figure 22A] This is a plan view of a patterned nonwoven fabric before and after hydraulic treatment, according to an exemplary embodiment of the present invention; [Figure 22B] This is a plan view of a patterned nonwoven fabric before and after hydraulic treatment, according to an exemplary embodiment of the present invention; [Figure 23A] This is a plan view of a patterned nonwoven fabric before and after hydraulic treatment, according to an exemplary embodiment of the present invention; [Figure 23B] This is a plan view of a patterned nonwoven fabric before and after hydraulic treatment, according to an exemplary embodiment of the present invention.

[0093] Detailed description of the invention This invention relates to an improved technique for hydrostatic treatment of nonwoven fabrics to form holes, and to a nonwoven fabric manufactured using this method.

[0094] Nonwoven fabrics subjected to hydrostatic treatment and / or perforation according to the present invention may be suitable for use in disposable absorbent articles. As used herein, the term “absorbent article” refers to an article that absorbs and retains fluids and solids. For example, an absorbent article may be placed directly on or in close proximity to the body to absorb and retain various exudates discharged from the body. An absorbent article may be a wearable article such as an infant diaper, an adult incontinence product, a feminine hygiene product, or a sanitary product used by healthcare workers to absorb fluids and solids, such as a disposable gown or zipper. In particular, a nonwoven fabric according to an exemplary embodiment of the present invention may be used as a body contact layer of an absorbent article, such as a surface sheet, or as part thereof, or may be used to form other components of an absorbent article, such as a backing sheet, a waist belt, or a fastening tab. A nonwoven fabric according to an exemplary embodiment of the present invention may also be used to pack or package articles such as absorbent articles. The term “single-use” is used herein to describe absorbent articles that are not intended to be washed, restored, or reused, but rather intended to be discarded after a single use, preferably recycled, composted, or disposed of in an environmentally friendly manner.

[0095] The term "butt" is used herein to refer to multiple fibrous materials before they are bonded together. A "butt" typically consists of individual fibers that are not bonded to each other, although some degree of pre-bonding may occur between the fibers, which may be performed, for example, during or immediately after the fiber laying in the spunmelt process. However, this pre-bonding still allows a considerable number of fibers to move freely and change position. A "butt" may consist of several layers obtained by depositing fibers from several spinning heads in the spunmelt process. There are no significant differences in fiber diameter and porosity distribution among the "sub-layers" laid from individual heads. Adjacent layers of fibers do not need to be separated from each other by abrupt transitions, and individual layers may be partially mixed in the regions near their boundaries.

[0096] The terms "fiber" and "filament" are used interchangeably in this application unless otherwise specified (for example, "endless filament" or "short fiber").

[0097] As used herein, the terms “nonwoven, nonwoven fabric, sheet, or textile” refer to a sheet or textile manufactured from directionally or randomly oriented fibers or filaments. These fibers or filaments are first formed into vats, then one or more vats are laid on top of each other, and then compacted and bonded together. Compaction and bonding are carried out by friction, cohesive force, adhesion, or localized compression and / or the application of pressure, heat, ultrasound, or heating energy, or a combination thereof, resulting in the bonding and bonding indentations of one or more patterns. This term does not include fabrics bonded by weaving, knitting, or sewing twisted yarns or filaments. The fibers may be of natural or artificial origin, and may be staple filaments or continuous filaments, and may be formed in situ. Commercially available fibers have a diameter of approximately 0.0005 mm to 0.25 mm and come in several different forms: short fibers (known as staple fibers or chopped fibers), continuous single fibers (filaments or monofilaments), untwisted bundles of continuous filaments (tow), and twisted bundles of continuous filaments (twisted yarn). Nonwoven fabrics can be formed by numerous processes, including, but are not limited to, meltblown, spunbond, spunmelt, solvent spinning, electrospinning, worsting, film microfibre, molten film microfibre, air laying, dry laying, wet laying using staple fibers, and combinations of these processes known in the art. The basis weight of nonwoven fabrics is usually expressed in grams per square meter (gsm).

[0098] The term "spunmelt fiber" refers to a fiber formed by heating a thermoplastic polymer (e.g., polypropylene, polyester, or nylon) and then extruding the polymer through a metal plate with hundreds of holes, known as a spinneret or die. Examples of spunmelt fibers include spunbond fibers and meltblown fibers. Spunmelt fibers may be monocomponent, formed from a single polymer component or a single blend of polymer components; or the cross-section of each fiber may be multicomponent, consisting of at least two individual polymer components or a blend of polymer components, or at least one individual polymer component and at least one individual blend of polymer components. Fibers having two individual components are sometimes called two-component fibers.

[0099] Fabrics or cloths manufactured using spunmelt fibers are sometimes called "spunmelt fabrics or cloths."

[0100] As used herein, the term "spunbond fiber" refers to a nearly continuous fiber or filament with an average diameter in the range of 10 to 30 microns. This also includes divisible two-component or multi-component fibers with an average diameter in the range of 50 to 30 microns before splitting.

[0101] As used herein, the term "meltblown fiber" refers to a nearly continuous fiber or filament with an average diameter of less than 10 microns.

[0102] The measured values ​​"filament diameter," "fiber diameter," or "fiber thickness" are expressed in μm units. The terms "filament diameter," "fiber diameter," and "fiber thickness" are interchangeable. The terms "grams of filament per 9000m" (denier or den) or "grams of filament per 10000m" (dTex) are used to express the degree of fineness or roughness of the filament, as they correlate with the product of the filament diameter (assuming a circular filament cross-section) and the density of the material(s) used.

[0103] As used herein, the term “fully bonded nonwoven fabric” refers to a nonwoven fabric in which fibers are fused to each other by melt-solidification in adhesive indentations, as is well known to those skilled in the art. Such fabrics may be converted into various uses, such as diapers, or used as a precursor for further processing (e.g., hydrophilic spin-finish coating or hydrostatic treatment). For example, fully bonded nonwoven fabrics may be produced by passing a vat through a nip point between two heated rolls under pressure, thereby forming a pattern of melt-embossed indentations on the fabric. The temperature and pressure within the nip are sufficient to soften and melt the individual fibers, and then fuse the fibers together using a pattern of protrusions on at least one of the heated rolls, forming a series of melt-bonded indentations. Here, most of the fibers within the melt-bonded indentations are no longer distinguishable as individual fibers. The adhesive indentations fuse the fibers together, or, in the case of two-component fibers, at least one component with the lowest melting temperature fuses over the entire thickness of the fabric. The temperature and pressure of the rolls are adjusted according to the composition and basis weight of the fabric. For example, 100% polypropylene spunbond of 20-25 gsm is typically bonded at roll temperatures exceeding 150°C and nip pressures exceeding 90 N / mm. Temperature / pressure settings are adjusted to accommodate various basis weights and / or line speeds. Higher basis weights and / or line speeds may require higher nip pressures and / or temperatures to achieve a "fully" bonded fabric with a fusion point. It should be understood that temporary bonding is not within the scope of the definition of "fully bonded" for the purposes of this disclosure.

[0104] As used herein, the term "adhesion area percentage" refers to the ratio of the area occupied by adhesive indentations to the total surface area of ​​the nonwoven fabric, expressed as a percentage, and is measured according to the adhesion area percentage method described herein.

[0105] With respect to the manufacture of nonwoven fabric materials and the nonwoven fabric materials themselves, the “crossing direction” (CD) refers to a direction along the fabric material that is approximately perpendicular to the direction of advancement of the fabric material in a manufacturing line for fabric materials. With respect to a bat in which the nips of a pair of calendar rollers move to form an adhesive nonwoven fabric, the crossing direction is perpendicular to the direction in which the nips move and parallel to the nips.

[0106] With respect to the manufacture of nonwoven fabric materials and the nonwoven fabric materials themselves, the "machine direction" (MD) refers to the direction along the fabric material that is approximately parallel to the direction of advancement of the fabric material in a manufacturing line for manufacturing fabric materials. With respect to a nonwoven vat that moves the nips of a pair of calender rollers to form an adhesive nonwoven fabric, the machine direction is parallel to the direction in which the nips move and perpendicular to the nips.

[0107] An "adhesive projection" or "projection" is a feature of the adhesive roller located radially on the outermost surface, surrounded by a concave region. With respect to the axis of rotation of the adhesive roller, the adhesive projection has a radially outermost adhesive surface whose adhesive surface shape and adhesive surface shape area generally follow an outer cylindrical surface with a radius approximately constant from the axis of rotation of the adhesive roller; however, multiple projections with individual and distinct adhesive surfaces are so small relative to the radius of the adhesive roller that the adhesive surface often appears flat / planar; and the adhesive surface shape area closely approximates a planar area of ​​the same shape. The adhesive projection may have a side perpendicular to the adhesive surface, but this side is usually inclined such that the cross-section of the base of the adhesive projection is larger than the adhesive surface. Multiple adhesive projections may be arranged in a pattern on the calendar roller. Multiple adhesive projections have an adhesive area per unit surface area of ​​the outer cylindrical surface, which can be expressed as a percentage and is the ratio of the sum of the adhesive shape areas of multiple projections within a unit to the total surface area of ​​the unit.

[0108] In nonwoven fabrics, “adhesive indentations” or “fused adhesive indentations” refer to surface structures formed by indentations of adhesive protrusions on a calender roller onto the nonwoven fabric. Adhesive indentations refer to portions of molten or heat-fused material that deform, interlock, or entangle from overlapping and pressurized fibers in the Z direction beneath the adhesive protrusions, forming adhesive or bonded regions. In the nonwoven structure, individual bonded areas may be connected by loose fibers between them. The shape and dimensions of the adhesive indentations substantially correspond to the shape and dimensions of the bonding surfaces of the adhesive protrusions on the calender roller. For the purposes of this disclosure, “thickness of the adhesive indentation” is understood to mean the width of the adhesive indentation region on the nonwoven fabric plane. One or both circumferential surfaces of the roller may be machined, etched, engraved, or otherwise formed to have an adhesive pattern of adhesive protrusions and recessed regions thereon, so that the adhesive pressure applied to the butt at the nip is concentrated on the bonding surface of the adhesive protrusions and reduced or nearly eliminated in the recessed regions. The bonding surface has an adhesive surface shape. As a result, an indentation pattern of interfiber adhesion is formed on the nonwoven fabric, which forms a fabric having adhesive indentations and adhesive shapes corresponding to the pattern of adhesive protrusions on the roller and the adhesive surface shape. A repeating pattern of adhesive protrusions and recessed areas may be formed on the adhesive roller. The adhesive shape represents the raised surface of the adhesive protrusions on the roller, and the area between the raised surface represents the recessed area. The adhesive shape of the adhesive protrusions is imprinted on the fabric as multiple adhesive indentations of similar shape in the calendar bonding (or calendar) process.

[0109] Figure 1 is a block diagram showing various components used in a process for producing a porous nonwoven fabric according to an exemplary embodiment of the present invention. The process shown in Figure 1 results in a nonwoven fabric having a spunbond-meltblown-spunbond (SMS) structure (2:3:4), but it should be understood that the process may be reconfigured to form many other fabric structures consisting of one or more spunbond layers and / or one or more meltblown layers, such as fabrics having one or more spunbond layers. More specific examples include S, SS, SSS, etc.; fabrics combining spunbond layers and meltblown layers, typically fabrics having spunbond layers forming at least one outer surface of the fabric, more specific examples of asymmetrical compositions include fabrics such as SSMS, SMSSMMS, SSMMS, SMMMSS, or examples of symmetrical compositions include fabrics such as SMS, SMMS, SMMMS, SSMSS; fabrics combining spunmelt layers with other layers, more specific examples including combinations of spunmelt layers formed from endless filaments and short fibers formed from natural materials. The nonwoven fabric structures are not limited to the examples provided herein, and those skilled in the art will understand that many other such structures can be obtained by changing the number and arrangement of process components.

[0110] In general, the number and configuration of beams are not limited to those shown and described herein, and it should be understood that in other exemplary embodiments, the number and configuration of beams may be varied to achieve different fabric structures. For example, a single spunbond beam may be used to form a nonwoven batt 6 on a conveyor belt 8 having a single spunbond layer, or multiple spunbond beams may be used to form a batt 6 having a multi-spunbond layer structure such as SS, SSS, SSSS, etc. The layers formed by multiple beams may be the same or very similar to each other in terms of filament type, process parameters, etc., so that the multiple layers are almost indistinguishable from each other and thus appear as a single-layer structure. Alternatively, the multiple layers may be manufactured to be different from each other, thus forming a clearly layered nonwoven product.

[0111] In another exemplary embodiment, only spunbond beam 2 and meltblown beam 3 are used to form a nonwoven vat 6 on a conveyor belt 8. According to a further exemplary embodiment of the present invention, multiple elements corresponding to beams 2 and 3 may be incorporated into the system to form a vat 6 having multiple layers, such as SM, SMM, SSM, SSMM, etc. In this case as well, the layers formed by the multiple beams may be the same or very similar to each other in terms of filament type, process parameters, etc., so that the multiple layers are almost indistinguishable from each other and thus appear as a single-layer structure. Alternatively, the multiple layers may be manufactured to be different from each other, thus forming a clearly layered nonwoven product.

[0112] According to an exemplary embodiment of the present invention, the spunmelt nonwoven vat 6 is manufactured from continuous filaments laid in a random distribution on a moving conveyor belt 8. The resin pellets may be processed into a molten material under heating and then supplied to spinnerets (or spinning beams 2 and 4) to create hundreds of filaments using a stretching device (not shown). Multiple spinnerets or beams (blocks arranged in a column) may be used to increase the density of spunbond fibers corresponding to, for example, spinning beams 2 and 4. The fibers are stretched from beams 2 and 4 by a jet of fluid (such as air) and then blown onto or transported onto a moving fabric (belt conveyor) 8, where the fibers are laid and sucked from the fabric 8 in a random pattern using a suction box (not shown) to form the vat 6. The meltblown layer may be accumulated between the spunbond layers laid by the spinning beams 2 and 4, preferably by a meltblown mechanism (or "beam") 3. The meltblown ("MB") layer can be formed by a meltblown process, but may also be formed by various other known processes. For example, a meltblown process includes the step of inserting a thermoplastic polymer into a die. The thermoplastic polymer material is extruded through multiple fine capillaries in the die to form fibers. The fibers are then passed through a high-speed gas (e.g., air) stream that dampens the flow of molten thermoplastic polymer material, reducing the fiber diameter to microfiber diameter. The meltblown fibers are then piled up semi-randomly by a beam 3 on a moving fabric, or on a moving fabric on which a spunbond layer has been laid by a spinning beam 2, to form a meltblown layer. To increase fiber coverage, one, two, or more meltblown blocks may be used in tandem. The meltblown fibers can be made adhesive when piled up, resulting in some degree of adhesion between the meltblown fibers on the fabric.

[0113] In preferred embodiments, the fibers used to form the butt 6 are thermoplastic polymers, examples of which include polyolefins (e.g., polypropylene "PP" or polyethylene "PE"), polyesters (e.g., polylactic acid "PLA", polyhydroxyalkanoate "PHA", polyhydroxybutyrate "PHB", polybutylene succinate "PBS", or polyethylene terephthalate "PET"), polyamides, polysaccharides (e.g., thermoplastic starch "TPS" or starch-based polymers), copolymers of these (with olefins, esters, amides, or other monomers), and blends thereof. Preferably, the fibers are made from polyolefins. Examples of polyolefins include polyethylene, polypropylene, its propylene-butylene copolymers, and blends thereof, such as ethylene / propylene copolymers and polyethylene / polypropylene blends. Resins with high crystallinity and low elongation at break may also be preferred because they tend to be more rupture-prone. The fibers may also be formed from non-oily components such as aliphatic polyesters, thermoplastic polysaccharides, or other biopolymers, or may contain these substances as additives or modifiers. As used herein, the term “blend” encompasses a homogeneous or semi-homogeneous mixture of at least two polymers.

[0114] Another approach involves forming nonwoven fabrics of multi-component, or preferably "two-component," polymer fibers. Such two-component polymer fibers may be formed using a spinneret having two adjacent sections, where the two sections represent a first component consisting of one polymer or blend and a second component consisting of the other polymer, forming a fiber having a cross-section of the first component in one section and the second component in the other (hence the term "two-component"). It is advantageous to select the components so that they have different melting temperatures and / or expansion-contraction rates. These different attributes of the two polymers may cause the two-component fiber product to be curved or crimped during the spinning process when cooled and drawn from the spinneret, when combined in aligned sheath-core or asymmetrical sheath-core configurations. The resulting crimped fibers may then be laid on a vat and calendered in a pattern. The crimping of the fibers is thought to give the fabric a rough and fuzzy texture, promoting a visual and tactile sign or characteristic of softness.

[0115] Other formulation modifications, such as the addition of CaCO3, may be made to provide spunbond fibers that are prone to breakage and / or permanent deformation, thereby improving porosity formation. Those skilled in the art will understand that many other formulation modifications, such as coloring additives, process additives, filament surface modifiers, and softening accelerators, may be made depending on additional requirements for the final fabric properties or specific spunmelt line requirements.

[0116] In exemplary embodiments, the butt 6 may be thermally calendered via rollers 10 and 12. One or both of the circumferential surfaces of rollers 10 and 12 may be machined, etched, engraved, or otherwise formed to have a pattern of protrusions and recessed areas thereon, so that the bonding pressure applied to the butt 6 at the nip is concentrated on the outer surface of the protrusions and reduced or nearly eliminated in the recessed areas. According to exemplary embodiments of the present invention, roller 10 is a calendering roll, and roller 12 is a bonding roll that defines the bonding pattern. A fully bonded precursor fabric 7 is obtained by thermal calendering. Preferred bonding patterns according to exemplary embodiments of the present invention are further described below.

[0117] According to an exemplary embodiment of the present invention, the precursor nonwoven fabric 7 is then subjected to hydraulic treatment using a plurality of water jet sprayers 16a, 16b, and 16c. Each of the elements 16a, 16b, and 16c shown in Figure 1 may represent a set of multiple sprayers in their respective predetermined arrangements. According to an exemplary embodiment of the present invention, as the precursor nonwoven fabric 7 is conveyed by the belt 22 under the sprayers 16a-16c, the high-pressure water jets from the sprayers 16a, 16b, and 16c strike and pass through the fabric. In an exemplary embodiment, the belt 22 is provided with a plurality of pins in a specific pattern for imparting holes to the precursor nonwoven fabric 7. According to an exemplary embodiment of the present invention, each pin has a base, and the distance between the centers of directly adjacent pins is at least 100% of the diameter of the base, and in a preferred exemplary embodiment, 150% of the diameter of the base.

[0118] Below the location of each spraying device (set) 16a to 16c, corresponding water removal systems 20a, 20b, and 20c may be placed to suck up and remove water and dry the foreground fabric 7. The water removal systems 20a, 20b, and 20c may be equipped with, for example, a vacuum box, a suction box, a Uhle box, a fan, and / or a vacuum slot. The nonwoven foreground fabric 7 may then be dried by blowing hot air through the fibrous fabric using an infrared (IR) dryer or other drying technique (e.g., air drying).

[0119] According to exemplary embodiments of the present invention, the belt 22 incorporates one or more screens (not shown), each screen having a predetermined pattern that supports the precursor nonwoven fabric 7 while being subjected to hydraulic treatment by its respective water jetting device 16a-16c. As will be described in more detail below with reference to Figures 2A and 2B, the one or more screens may be replaced by one or more drums 14, one drum, or the last drum in a series of drums, comprising a sleeve 18. The screen(s) or sleeve may comprise a plurality of pins in a specific pattern for imparting holes to the precursor nonwoven fabric 7. According to exemplary embodiments of the present invention, fewer than three sets of jetting devices 16a-16c may be used to hydraulically treat and / or pore the precursor nonwoven fabric 7.

[0120] According to exemplary embodiments of the present invention, water injection is divided into multiple steps by using one or the last drum in a series of drums having a sleeve with a pin pattern, and further using one or more drums, each connected to one or more water injection devices. The desired water pressure in each step depends on many parameters, such as the number of water injection steps and the line speed. Generally, the more water injection steps used in the process, the lower the pressure required in each step to achieve the desired fabric properties. In other words, the energy flux obtained by multiple water injection devices each applying a specific amount of water pressure can also be obtained by increasing the number of water injection devices and decreasing the water pressure applied by each device. The desired water pressure in each step also depends, at least in part, on the line speed. The faster the line speed, the higher the pressure required to maintain a constant flux. In other words, the energy flux obtained by line speed and injection device pressure can also be obtained by lowering both line speed and injection device pressure.

[0121] Without being bound by theory, the preferred total water jet pressure applied to the precursor fabric 7 may be expressed in terms of energy flux. According to an exemplary embodiment, the preferred energy flux applied to the precursor fabric 7 is at least 0.2 kWh / kg, preferably at least 0.3 kWh / kg, preferably at least 0.5 kWh / kg, preferably in the range of 0.2 to 3.0 kWh / kg, preferably in the range of 0.3 to 1.9 kWh / kg, and more preferably in the range of 0.5 to 1.9 kWh / kg. For example, the desired energy flux may be obtained by changing the mechanical speed and / or water pressure in each water jet device. The desired energy flux is preferably achieved by using one or more water jet devices at relatively low pressure, rather than by reducing the number of water jet devices at high pressure. The energy flux may be calculated using the following formula:

[0122] Flux = ((J^1.5)*(G^2)*(I)*(L / 1000)*(7 / 10000000000)) / F: Therefore TIFF0007874662000001.tif20137J=Water pressure (bar) G = Jet zone diameter (microns) I = Number of holes / Jet zone length (m) L = width of nonwoven fabric (m) F = Nonwoven fabric mass flow rate (i.e., the amount of nonwoven fabric processed calculated based on line speed, product width, and basis weight) (kg / hr)

[0123] In an exemplary embodiment using a series of drums, pins on the last drum in the process line create holes throughout the precursor fabric 7. In this regard, the drum preceding the last drum in the process line may preferably not have pins and instead have a mesh screen. In an exemplary embodiment, the second to last drum in the drum line may have pins to prepare the precursor fabric for hole formation, but even in this case, the actual opening / hole formation of the precursor fabric 7 is preferably performed on the last drum. It should be understood that in other exemplary embodiments of the present invention, the pins may be provided on a belt instead of on a drum.

[0124] In a preferred exemplary embodiment of the present invention, a relatively large number of water jets are used. Without being bound by theory, increasing the number of jets used can increase the line velocity without the need to increase the jet pressure. Note that, for the purposes of this disclosure, two or more water jets with the same settings (particularly regarding the number and shape of the water jets and the water pressure) are considered as a single water jet.

[0125] In exemplary embodiments, the water injection process may include a step of feeding a fully calendered polyolefin nonwoven precursor fabric 7 to a plurality of water injection devices, with a water pressure of 180 bar, preferably 200 bar or more, applied by each water injection device. In exemplary embodiments, the basis weight of the precursor fabric 7 is 15 to 45 gsm, and the line speed is 150 to 450 m / min, while in more specific examples, the basis weight of the precursor fabric is 25 gsm, and the line speed is 200 m / min.

[0126] In exemplary embodiments, the water spraying process may include a step of subjecting the fully calender-bonded polyolefin nonwoven precursor fabric 7 to two water spraying devices, each water spraying device applying a water pressure of 250 bar, preferably 300 bar or more. In exemplary embodiments, the basis weight of the precursor fabric 7 is 15 to 45 gsm and the line speed is 150 to 450 m / min, and in more specific examples, the basis weight of the precursor fabric is 25 gsm and the line speed is 200 m / min.

[0127] In exemplary embodiments, the water injection process may include a step of subjecting the fully calendered polyolefin nonwoven precursor fabric 7 to at least four water injection devices, each water injection device applying a water pressure of 150 bar or more. In exemplary embodiments, the basis weight of the precursor fabric 7 is 15 to 45 gsm and the line speed is 150 to 450 m / min, and in more specific examples, the basis weight of the precursor fabric is 25 gsm and the line speed is 200 m / min.

[0128] In exemplary embodiments, the water spraying process may include a step of subjecting the fully calendered polyester nonwoven precursor fabric 7 to at least three water spraying devices, each water spraying device applying a water pressure of 60 bar, preferably 75 bar or more. In exemplary embodiments, the basis weight of the precursor fabric 7 is 15 to 45 gsm and the line speed is 150 to 450 m / min, and in more specific examples, the basis weight of the precursor fabric is 25 gsm and the line speed is 200 m / min.

[0129] In exemplary embodiments, the water spraying process includes a step of feeding the fully calendar-adhered nonwoven precursor fabric 7 to three water spraying devices (each water spraying device having a set of spraying devices / nozzles), each water spraying device applying a higher water pressure than the water spraying device immediately preceding it in the machine direction. For example, water spraying device 16c may apply a higher water pressure than water spraying device 16b, and water spraying device 16b may apply a higher water pressure than water spraying device 16a. In specific exemplary embodiments, water spraying device 16b applies a water pressure of at least 80%, preferably 80% to 95%, of the water pressure applied by water spraying device 16c, and water spraying device 16a applies a water pressure of at least 80%, preferably 80% to 95%, of the water pressure applied by water spraying device 16b. In embodiments, water spraying device 16a applies a water pressure of at least 64%, preferably 64% to 90%, of the water pressure applied by water spraying device 16c. When the water injection device 16a applies a relatively low water pressure, initial softening of the precursor fabric occurs before holes are formed. When the water injection device 16b applies a relatively high water pressure, the individual adhesive indentations begin to change (as will be explained in more detail below), preparing the precursor fabric for hole formation. Finally, when the water injection device 16c applies the highest water pressure in the machine direction, holes are formed in the precursor fabric, and the individual adhesive indentations change further. Without being bound by theory, it is thought that the increasing gradient of applied water pressure helps to maintain the individual adhesive indentations during the softening and preparation stages of the process, and controls the changes in the individual adhesive indentations along with hole formation in the final stage.

[0130] In the embodiment, the water injection process includes a step of feeding the heat-bonded nonwoven precursor fabric 7 to two water injection devices (each water injection device has a set of injection devices / nozzles), where each water injection device applies a higher water pressure than the water injection device immediately preceding it in the machine direction. For example, water injection device 16c may apply a higher water pressure than water injection device 16b, and water injection device 16a may be omitted.

[0131] In the embodiment, the water spraying process includes a step of providing the heat-bonded nonwoven precursor fabric 7 to four or more water spraying devices (each water spraying device has a set of spraying devices / nozzles), where each water spraying device applies a higher water pressure than the water spraying device immediately preceding it in the machine direction.

[0132] In an exemplary embodiment, the step of imparting a plurality of pores to a fully bonded precursor nonwoven fabric by water pressure includes a step of altering at least partially the individual adhesive indentations by applying water pressure. In this regard, by applying water pressure, at least a portion of the fully bonded portion of each adhesive indentation is removed, thereby leaving at least 60%, preferably at least 70%, more preferably 80%, and even more preferably 90% of the fully bonded portion of each adhesive indentation after the step of imparting by water pressure.

[0133] In embodiments, individual adhesive indentations may be separated into at least two parts by applying water pressure. In embodiments, the overall dimensions of individual adhesive indentations may be reduced by applying water pressure while maintaining the general characteristics of each individual adhesive indentation. For example, as shown in Figures 20A-20C, 22A, and 22B, in the case of elliptical adhesive indentations (e.g., pattern 1), the change may reduce the dimensions of the elliptical shape while maintaining the general elliptical outline of the adhesive indentation. As a further example, as shown in Figures 21A-21C, 23A, and 23B, in the case of S-shaped adhesive indentations (e.g., pattern 3) having relatively thin linear adhesive regions forming an S-shape, the change may separate the S-shaped line into several parts. Without being bound by theory, it is believed that at least partial changes to individual adhesive indentations improve tactile softness and do not significantly reduce the tensile strength and / or abrasion resistance of the final product. Tactile softness is a complex value that is difficult to express through simple measurements, much like how human fingers express sensation. The values ​​measured in this application (caliper, handle ometer (HOM), coefficient of friction (COF)) are partial measurements of tactile softness, and these values ​​do not comprehensively represent tactile softness.

[0134] In the embodiment, as shown in Figures 19A to 19F, by applying water pressure, the fibers in the region surrounding the outer edge of each adhesive indentation fray randomly inside and outside the main plane of the completely bonded precursor nonwoven fabric, and the natural reinforcing fibers are at least partially removed around the outer edge of the adhesive indentation, thereby making at least a portion of each adhesive indentation non-three-dimensional. More specifically, Figure 19A is a cross-sectional view showing the formation of individual adhesive indentations at the edge of the adhesive indentation by a pattern processing calendar roll 12 and a smoothing calendar 10 using natural reinforcing fibers; Figure 19B is a cross-sectional view of the individual adhesive indentations 100 and the bonded precursor fabric having natural reinforcing fibers at the edge of the adhesive indentation; and Figure 19C is a cross-sectional view showing the water-pressure treated nonwoven fabric with altered individual adhesive indentations, in which there are no natural reinforcing fibers at the edge of the adhesive indentation, and the adhesive indentation itself is also somewhat smaller. Figure 19D is a cross-sectional micrograph of a modified individual adhesive indentation according to an exemplary embodiment of the present invention, showing how the edges around the adhesive indentation fray and the natural reinforcing fibers disappear around the outer edge of the adhesive indentation due to treatment with water flow / water pressure. In contrast, Figures 19E and 19F are cross-sectional micrographs of a conventional precursor adhesive indentation, as shown in U.S. Patent No. 8,410,007, where the natural reinforcing fibers are clearly visible.

[0135] Without being bound by theory, it is thought that the randomization of fibers around the outer edges of individual adhesive indentations results in a softer final product (tactile softness).

[0136] Figures 2A and 2B show exemplary embodiments of the present invention employing one or more drums for imparting holes to a nonwoven fabric. Similar elements are given the same reference numerals as in Figure 1, and a detailed description of these elements is omitted herein.

[0137] As shown in Figure 2A, spunbond beam 2, meltblown beam 3, and spunbond beam 4 may be used to form a bat 6 on a conveyor belt 8. The bat 6 may then be bonded with calendar rolls 10 and 12 to form a fully bonded precursor nonwoven fabric 7. In this case as well, according to further exemplary embodiments of the present invention, multiple elements corresponding to each of the beams 2, 3, and 4 may be incorporated into the system to form each of the multiple layers of the bat 6, for example, by accumulating multiple meltblown layers to form an SM or SMS type fabric. It should be understood that the number, type, and arrangement of beams are not limited to those described and shown herein. It should also be understood that by changing the number, type, and / or arrangement of beams, any other combination of meltblown, spunbond, and / or meltblown / spunbond fabric structures may be formed according to exemplary embodiments of the present invention.

[0138] According to an exemplary embodiment of the present invention, the fabric 7 passes around the drum 14 as one or more water jetting devices 16 apply water pressure to the fabric 7, thereby imparting a plurality of holes to the nonwoven precursor fabric 7 by water pressure. According to an exemplary embodiment of the present invention, the drum 14 may be covered with a metal or plastic sleeve 18, which has a predetermined pattern of pins that form holes in the precursor fabric / fabric 7 under the influence of the water pressure applied by the water jetting devices 16. According to an exemplary embodiment of the present invention, the pins have a base, and the distance between the centers of the pins is at least 100%, preferably at least 150%, and more preferably at least 200% of the diameter of the base. For the purposes of this measurement, as shown in Figure 3, the base means the portion of the pin just before it begins to spread outward and contacts the flat portion of the sleeve. If the base of the pin is not circular, “diameter” means the length of the shortest dimension traversing the base of the pin (for example, if the pin is elliptical, “diameter” is the length of the minor axis of the ellipse).

[0139] The precursor nonwoven fabric 7 is wound onto a drum 14, and as the fabric 7 passes under the spraying device 16, the high-pressure water jet from the spraying device 16 hits the fabric, passes through it, and deforms the fabric according to the pattern of pins on the sleeve 18. A water removal system 20 is placed below the position of each spraying device 16 to remove the water by suction or through the holes. Thus, holes are formed in the precursor fabric (fabric 7) in a pattern corresponding to the pattern of pins on the sleeve 18 beneath the fabric 7. The porous nonwoven fabric 9 may then be dried by blowing hot air onto the fibrous fabric, using an infrared (IR) dryer or other drying techniques (e.g., air drying).

[0140] According to exemplary embodiments of the present invention, the pin height is at least 100% of the thickness of the porous nonwoven fabric, preferably at least 115%, and more preferably at least 130% of the thickness of the porous nonwoven fabric, the thickness of which is measured on the final dried product. For the purposes of this disclosure, the pin height refers to the height measured from the base to the top of the pin as described above.

[0141] According to exemplary embodiments of the present invention, the pin height is at least 150%, preferably at least 200%, preferably at least 250%, and more preferably at least 300% of the thickness of the precursor fabric, the thickness of which is measured on the dry precursor before water treatment.

[0142] As shown in Figure 2A, hole formation may be performed on one drum 14 using at least one, preferably more than one, water jet beam (injector 16) so as not to disturb the clarity of the hole formation pattern when subsequent drums are used.

[0143] According to an exemplary embodiment of the present invention, using a single drum 14 of Figure 2A having a sleeve with a pin pattern, the water injection becomes a multi-step process by connecting the single drum 14 to one or more water injection devices. The desired water pressure in each step depends on the number of water injection steps. According to the exemplary embodiment, the preferred energy flux applied to the forelay fabric 7 is in the range of 0.2 to 3.0 kWh / kg, preferably in the range of 0.3 to 1.9 kWh / kg. The desired energy flux may be obtained, for example, by changing the mechanical speed and / or water pressure in each water jet. Preferably, the desired energy flux is obtained by using one or more water injection stations with relatively low pressure, rather than using a few water injection stations with high injection pressure.

[0144] In exemplary embodiments, the water jetting process may include a step of subjecting the fully calendered nonwoven precursor fabric 7 to three sets of water jetting devices as the fabric moves around a single drum 14, with each of the water jetting devices applying a water pressure of 200 bar or more. In exemplary embodiments, the basis weight of the precursor fabric 7 is 15 to 45 gsm and the line speed is 150 to 450 m / min, and in more specific examples, the basis weight of the precursor fabric is 25 gsm and the line speed is 200 m / min.

[0145] In exemplary embodiments, the water jetting process may include a step of subjecting the fully calendered nonwoven precursor fabric 7 to two sets of water jetting devices as the fabric moves around a single drum 14, with each water jetting device applying a water pressure of 250 bar or more. In exemplary embodiments, the basis weight of the precursor fabric 7 is 15 to 45 gsm and the line speed is 150 to 450 m / min, and in more specific examples, the basis weight of the precursor fabric is 25 gsm and the line speed is 200 m / min.

[0146] In exemplary embodiments, the water jetting process may include a step of subjecting the fully calendered nonwoven precursor fabric 7 to at least four water jetting devices as the fabric moves around a single drum 14, with each water jetting device applying a water pressure of 150 bar or more. In exemplary embodiments, the basis weight of the precursor fabric 7 is 15 to 45 gsm and the line speed is 150 to 450 m / min, and in more specific examples, the basis weight of the precursor fabric is 25 gsm and the line speed is 200 m / min.

[0147] Figure 2B shows a system for imparting holes to a nonwoven fabric using multiple drums, according to an exemplary embodiment of the present invention. As shown in Figure 2B, spunbond beams 2 and meltblown beams 3 may be used to form a bat 6 on a conveyor belt 8. The bat 6 may then be bonded with calendar rolls 10 and 12 to form a fully bonded precursor nonwoven fabric 7. In this case as well, according to a further exemplary embodiment of the present invention, multiple elements corresponding to each of beams 2 and 3 may be incorporated into the system, and multiple layers of the bat 6—for example, multiple meltblown layers—may be assembled to form an SMMS or SMMMS fabric. Again, it should be understood that the number, type, and arrangement of beams are not limited to those described and shown herein. It should also be understood that by changing the number, type, and / or arrangement of beams, any other combination of meltblown, spunbond, and / or meltblown / spunbond fabric structures may be formed according to an exemplary embodiment of the present invention.

[0148] As shown in Figure 2B, the process according to this exemplary embodiment involves the use of two drums, a first drum 14a and a second drum 14b, where the second drum 14b follows the first drum 14a along the process line. It should be understood that the number of drums is not limited to two, and the number of drums used can be arbitrary. According to the exemplary embodiment of the present invention, as one or more water jetting devices 16b apply water pressure to the fabric 7, the fabric 7 passes around drum 14b (the last drum in the line of two drums), thereby imparting multiple holes to the nonwoven precursor fabric 7 by water pressure. According to the exemplary embodiment of the present invention, drum 14b may be covered with a metal or plastic sleeve 18 having a predetermined pattern of pins that form holes in the precursor fabric / fabric 7. According to the exemplary embodiment of the present invention, the pins have bases, and the distance between the centers of the pins is at least 100%, preferably at least 150%, and more preferably at least 200% of the diameter of the bases.

[0149] The precursor fabric 7 is wound onto drums 14a and 14b, and as the fabric 7 passes under the spraying device 16b connected to the second drum 14b, the high-pressure water jet from the spraying device 16b hits the fabric, passes through it, and deforms the fabric according to the pattern of pins on the sleeve 18. Suction holes or suction slots / regions 20a and 20b are placed below the positions of each spraying device 16a and 16b to suction and remove the water or remove it through the holes. Thus, holes are formed in the precursor fabric (fabric 7) in a pattern corresponding to the pattern of pins on the sleeve 18 beneath the fabric 7. The porous nonwoven fabric 9 may then be dried by blowing hot air over the fibrous fabric, using an IR dryer or other drying technique (e.g., air drying).

[0150] The overall poring is preferably performed on the second (last in the line) drum 14b using at least one, preferably more than one, water jet beam (injector 16b) so as not to disturb the clarity of the poring pattern by subsequent drums. In this regard, the drum preceding the last drum in the process line (e.g., drum 14a) may preferably not have pins and instead have a mesh screen. In exemplary embodiments, the second to last drum in the drum line may have pins to prepare the precursor fabric for poring, but even in this case, the actual opening / poring of the precursor fabric 7 is preferably performed on the last drum.

[0151] According to exemplary embodiments of the present invention, the use of only the last drum 14b having a sleeve with a pin pattern is reduced to multiple water jetting steps by connecting the drum 14b to one or more water jetting devices. The desired water pressure in each step depends on the number of water jetting steps. According to exemplary embodiments, the preferred energy flux applied to the pre-fabric 7 is in the range of 0.2 to 3.0 kWh / kg, preferably in the range of 0.3 to 1.9 kWh / kg. The desired energy flux may be obtained, for example, by changing the mechanical speed and / or water pressure in each water jet. Preferably, the desired energy flux is obtained by using one or more water jetting stations at a moderate pressure, rather than using a few water jetting stations at a high jetting pressure.

[0152] In exemplary embodiments, the water jetting process may include a step of subjecting the fully calender-bonded nonwoven precursor fabric 7 to three water jetting devices as it moves around the drum 14b, with each water jetting device applying a water pressure of 300 bar or more. In exemplary embodiments, the basis weight of the precursor fabric 7 is 15 to 45 gsm and the line speed is 150 to 450 m / min, and in more specific examples, the basis weight of the precursor fabric is 25 gsm and the line speed is 200 m / min.

[0153] In exemplary embodiments, the water jetting process may include a step of subjecting the fully calender-bonded nonwoven precursor fabric 7 to two water jetting devices as it moves around the drum 14b, with each water jetting device applying a water pressure of 250 bar or more. In exemplary embodiments, the basis weight of the precursor fabric 7 is 15 to 45 gsm and the line speed is 150 to 450 m / min, and in more specific examples, the basis weight of the precursor fabric is 25 gsm and the line speed is 200 m / min.

[0154] In exemplary embodiments, the water jetting process may include a step of subjecting the fully calender-bonded nonwoven precursor fabric 7 to at least four water jetting devices as it moves around the drum 14b, with each water jetting device applying a water pressure of 150 bar or more. In exemplary embodiments, the basis weight of the precursor fabric 7 is 15 to 45 gsm and the line speed is 150 to 450 m / min, and in more specific examples, the basis weight of the precursor fabric is 25 gsm and the line speed is 200 m / min.

[0155] Without being bound by theory, the properties of the precursor nonwoven fabric are considered to strongly influence the characteristics of the final fabric. As described herein, the fully bonded precursor nonwoven fabric is subjected to hydropatterning, which forces the fibers in the fabric to form around pins on a screen through fiber migration, breakage, and / or inelastic deformation. This shape remains in the fabric, and thus the clarity of the pores becomes to a desired level, along with improvements in other attributes such as softness and mechanical stability. The key features of the precursor nonwoven fabric according to exemplary embodiments of the present invention are described below.

[0156] In exemplary embodiments, the percentage of the adhesive area of ​​the precursor nonwoven fabric may preferably be at least 5%, preferably at least 10%, and more preferably in the range of 10 to 25%. The “percentage of the adhesive area” of the nonwoven fabric is the ratio expressed as the percentage of the area occupied by the adhesive indentation relative to the total surface area of ​​the fabric, and is measured according to the “percentage of the adhesive area method” described herein. The method for measuring the percentage of the adhesive area is described in U.S. Patent No. 8,841,507, which is incorporated herein by reference in its entirety and is described below.

[0157] In exemplary embodiments, the precursor nonwoven fabric may have an adhesive pattern consisting of numerous adhesive indentations, each of which has a maximum measurable length and a maximum measurable width.

[0158] Figure 4 shows an adhesive pattern, referred to herein as “Pattern 3,” on a precursor nonwoven fabric according to an exemplary embodiment of the present invention. Each adhesive indentation has an adhesive shape 100 with a maximum measurable length L, which is measured by identifying the shape length line 104 that intersects the outer edge of the shape at the intersection at the maximum distance that can be identified on the outer edge, i.e., the distance between the two furthest points on the outer edge. As reflected in Figure 4, the adhesive shape 100 has a maximum measurable width W, which is measured by identifying the respective shape width lines 105a and 105b that are parallel to the shape length line 104 and touch the outer edge of the shape at one or more outermost points that are furthest from the shape length line 104 on both sides. It is understood that, depending on the shape (e.g., a semicircle), one of the shape width lines 105a and 105b may coincide with / collinear to the shape length line 104. The maximum measurable width W is the distance between the shape width lines 105a and 105b.

[0159] Within the scope of the present invention, the aspect ratio of the maximum measurable length L to the maximum measurable width W is at least 1.0, preferably at least 1.5, more preferably at least 2.0, and even more preferably at least 2.5. For example, in an ellipse within an elliptical pattern (referred to herein as "Pattern 1") according to an exemplary embodiment of the present invention, the aspect ratio of the maximum measurable length L to the maximum measurable width W is 1.8, and in a straight line within a straight line pattern (referred to herein as "Pattern 2"), the aspect ratio of the maximum measurable length L to the maximum measurable width W is 8.5. The adhesive shape and dimensions imprinted on the nonwoven fabric reflect and correspond to the adhesive shape 100 and dimensions on the calendar roller.

[0160] Without being bound by theory, it is believed that adhesive projections on a calendar roller having one or more of the features described herein exert an aerodynamic effect on the airflow within and around the calendar dip, accelerating and decelerating the air within and around the gaps of the nonwoven fibers in a manner that rearranges the fibers. This rearrangement of fibers may have an effect on breakage or fraying and may be advantageous in forming pore shapes around the pins during the hydro-patterning process as described herein.

[0161] Furthermore, oriented the protrusions to rotate can yield aerodynamic effects. In an exemplary embodiment, a pattern with spacing between adhesive indentations has an adhesive shape 100, and the adhesive protrusions supporting the adhesive shape 100 may be arranged along individual shape inclination angles that are oblique to the machine direction and the intersecting direction. Without intending to be bound by theory, it is preferable that the shape inclination angle does not exceed a certain amount so that the effect of the adhesive protrusions on the airflow is maximized. Referring again to Figure 4, the shape inclination angle αT may be expressed as the smaller of the angles formed by the intersection of the axis along the machine direction 108 and the shape length line 104. The shape and shape inclination angle are thought to exert a synergistic effect on the airflow. The shape inclination angle αT is thought to be preferably 65 degrees or less, more preferably 40 degrees, and even more preferably 30 degrees so as to give the airflow the desired effect. Shape inclination angles within this range are thought to effectively allow the airflow to pass through the nip while simultaneously imparting a vector component in the direction intersecting the airflow passing through the nip. Conversely, a shape inclination angle exceeding 50 degrees can significantly obstruct the airflow through the nip, potentially preventing any beneficial effects from being achieved. As the shape inclination angle increases further and the density of adhesive protrusions becomes sufficiently high, the airflow may not pass through the nip at all, but rather be deflected almost entirely away from the nip, creating a sufficient obstruction in the nip to direct the airflow towards the side of the adhesive roller. The adhesive shape and rotational orientation imprinted on the nonwoven fabric reflect and correspond to the adhesive shape and rotational orientation on the roller.

[0162] In another exemplary embodiment of the present invention, the adhesive indentations form a so-called “quilting pattern.” For the purposes of this specification, a nonwoven fabric having a quilting pattern is a nonwoven fabric having relatively large, regularly spaced non-adhesive regions. The non-adhesive regions are formed by the intersection of adhesive lines extending from opposing edges of the nonwoven fabric, usually diagonally across the fabric. The adhesive lines are spaced apart from each other, leaving non-adhesive regions between them. In exemplary embodiments, the surface area of ​​the non-adhesive regions is greater than the thickness of the adhesive lines measured across the surface of the fabric. For example, referring to Figure 9 (Pattern 4) showing a quilting pattern, the square surface area between the adhesive lines is preferably at least 3 times, more preferably at least 4 times, and most preferably at least 5 times the thickness of the adhesive lines. The adhesive lines may be formed from continuous lines arranged in a consistent direction or from individual adhesive points.

[0163] Regarding the quilting pattern, without being bound by theory, the inclination angle αTq of the quilting pattern is considered to be 60 degrees or less, preferably 50 degrees, and more preferably 40 degrees, in order to give the desired effect on the airflow. Referring to Figure 5, the pattern inclination angle αTq may also be represented as the smaller of the angles formed at the intersection of the axis along the machine direction 108 and the quilting pattern line 104q.

[0164] Without being bound by theory, it is thought that lower uniformity of filament orientation at the microscale tends to result in more stable hole edges in all directions. Conversely, it is thought that higher orientation uniformity at the microscale tends to result in the formation of holes with higher filament density on hole edges aligned in a preferred direction. To obtain the best results, it is considered that it may be even more desirable for the quilting pattern inclination angle αTq to be between 5 and 15 degrees, more preferably between 8 and 12 degrees, and even more preferably between 9 and 11 degrees. The rotational orientation of the adhesive pattern imprinted on the nonwoven fabric reflects and corresponds to the rotational orientation of the adhesive pattern on the roller.

[0165] Referring further to Figure 4, the adhesive shape 100 may have an outer edge with protrusions 102a and 102b on both sides of the shape length line 104. Figure 4 also shows that the radius (one or more) of the protrusions may be varied. In other exemplary embodiments, the adhesive shape 100 may contain only one protrusion (for example, to form a single arc shape rather than a shape with multiple arcs as shown in Figure 4). Adhesive protrusions having an adhesive surface that conforms to this description and are repeatedly arranged in a pattern are thought to have a beneficial effect on accelerating and decelerating air passing through the nonwoven fibers at and near the nip, and to provide advantages when forming holes in the fully bonded nonwoven around the pins. In this case as well, the adhesive shape and dimensions imprinted on the nonwoven fabric reflect and correspond to the adhesive shape and dimensions on the roller.

[0166] The outer edge of the shape may have convex portions on both sides of the length line of the shape, forming a symmetrical shape such as a circle or an ellipse. Such a shape can be seen in Pattern 1 referenced herein.

[0167] The outer edge of the shape may have convex portions on both sides of the shape length line 104, with or without varying radii, so that the overall contour of the outer edge of the shape becomes an airfoil with a symmetrical upward curve in cross-section. In another alternative example, the outer edge of the shape may have a convex portion on one side of the shape length line 104 and a straight portion on the other side, so that the overall contour of the outer edge of the shape becomes a wing / aircraft airfoil with an asymmetric upward curve in cross-section. In yet another alternative example, as reflected in Figure 4, the outer edge of the shape may have a convex portion on one side of the shape length line 104 and a concave portion 103 positioned substantially opposite the convex portion, such a shape is seen in Pattern 3 referenced herein.

[0168] Table 1 shows, but is not limited to, adhesive patterns that can be used in an exemplary embodiment of the present invention: [Table 1]

[0169] The adhesive indentation patterns 1 to 3 disclosed herein are each formed from multiple adhesive indentations, each having a finite area. Such adhesive indentations are called "discontinuous." Adhesive indentation pattern 4 is considered to be a single continuous adhesive indentation (quilting pattern) because the distance between adjacent adhesive indentations is the shortest at 0.6 mm.

[0170] From the examples presented, it can be seen that the dimensions of the adhesive indentations may differ, and therefore, even with the same adhesive area, the adhesive patterns may appear very different. For example, the small adhesive points in Pattern 1 are close to each other (approximately 50 adhesive indentations per square centimeter), while the large S-shaped adhesive indentations in Pattern 3 are relatively far apart (approximately 2.5 adhesive indentations per square centimeter). It should be noted that while particularly large adhesive shapes or quilting patterns are preferably formed by a single large adhesive indentation, they can also be composed of several small adhesive indentations that form the overall adhesive shape. For example, individual S-shapes within Pattern 3 may be formed from a number of small adhesive points or dots. For the purposes of this disclosure, if the minimum distance between adjacent adhesive indentations is less than 0.7 mm, preferably less than 0.5 mm, more preferably less than 0.4 mm, and most preferably less than 0.3 mm, then multiple adjacent adhesive indentations are considered as a single adhesive indentation.

[0171] In exemplary embodiments, the number of adhesive indentations per square centimeter of the precursor nonwoven fabric 7 is at least 20, preferably at least 30, more preferably at least 40, even more preferably at least 50, and even more preferably at least 60. For the purposes of this specification, adhesive indentations with a number of adhesive indentations per square centimeter within these ranges are considered “small” adhesive indentations.

[0172] In certain pattern designs, the method for determining the number of adhesive indentations per defined area may be unclear. This situation can occur, for example, with patterns having several different types of adhesive indentation dimensions or shapes, or with patterns that have non-adhesive areas used as part of the design. In such cases, the adhesive indentations have a total area (molten filament area) of 1 mm². 2 A size less than the specified value is considered small.

[0173] Without being bound by theory, the dimensions and shape of the adhesive indentations that constitute the adhesive pattern are thought to affect the final hydro-patterned fabric characteristics, such as the clarity of the holes, flexibility, rigidity, and pattern visibility. For example, if the adhesive indentations are small and significantly smaller than the holes they form, they are moved to the side by pins during the hydro-patterning process, resulting in a higher density of adhesive indentations compared to the pre-processed fabric, and consequently, improved rigidity of the porous fabric product (see Figure 10).

[0174] According to another exemplary embodiment, the adhesive indentations are large and may be equivalent in size to the dimensions of the holes, or in exemplary embodiments, larger in size to the dimensions of the holes. Such relatively large adhesive indentations may provide a precursor fabric with a relatively low adhesive indentation density, for example, less than 20 adhesive indentations per square centimeter, preferably less than 15 per square centimeter, more preferably less than 10 per square centimeter, and even more preferably less than 5 per square centimeter. For the purposes of this specification, adhesive indentations with a number of adhesive indentations per square centimeter within these ranges are considered “large” adhesive indentations.

[0175] Without being bound by theory, it is possible to obtain a fabric with highly distinct holes and adhesive indentations visible to the naked eye by using the large adhesive indentations on the precursor fabric 7 subjected to the hydraulic hole formation process described above. This is thought to result in a fabric with a desirable, highly visible design in terms of both holes and adhesive indentations.

[0176] Without being bound by theory, the shape and orientation of the adhesive indentation in the MD / CD direction are also thought to affect the clarity of the holes and the integrity of the adhesive pattern in hydro-patterned fabrics. For example, certain adhesive pattern shapes may interact unfavorably with the pins during the hydro-patterning process, reducing the clarity of the holes in the fabric and potentially damaging the adhesive pattern. In contrast, adhesive patterns arranged in rows and / or columns, and / or having a specific shape with spacing between the adhesive indentations, may avoid interference with the pin pattern, potentially resulting in highly clear holes where the adhesive indentation is visible and intact between the holes.

[0177] Without being bound by theory, it is thought that large adhesive indentations behave differently from small adhesive indentations during the hydropatterning process. For example, since large indentations do not easily move to the side during the hydropatterning process, the density of adhesive indentations does not change significantly compared to the density of the preceding fabric, even if it does. For example, as shown in Figure 11, the S-shaped adhesive indentations of pattern 3 provide space for pins arranged in a regular "square" pin pattern to form holes, and the shape, inclination, and length-to-width ratio of the indentations promote mechanical properties such as flexibility, along with the clarity of the holes. Since adhesive indentations can "flow" around the pins during the hydropatterning process, the S-shaped adhesive indentations of pattern 3 are visible to the naked eye on the fabric, as can be seen in Figure 11.

[0178] As another example, Figure 12 shows that, although not as clear as pattern 3, the adhesive indentations of pattern 4 (large dot quilting) are visible between the holes. Specifically, in this example, the precursor fabric was fully bonded using pattern 4, which consists of large circles and small rhombuses that are very close to each other. The small rhombuses act as miniature adhesive indentations and are not clearly visible to the naked eye after the hydro-patterning process. In contrast, the large circles of pattern 4 remain visible, and thus, when combined with the holes, the visual effect differs compared to the original heat-bonded pattern on the precursor.

[0179] In exemplary embodiments, the precursor nonwoven fabric 7 has multiple adhesive indentations of different dimensions. For example, WO2017190717 discloses an adhesive pattern consisting of primary and auxiliary adhesive indentations. In such circumstances, it is preferable to determine the density of large and small adhesive indentations separately. For example, the density of small (or auxiliary) adhesive indentations is better estimated from the area without considering the large (or primary) adhesive indentations.

[0180] In exemplary embodiments, the stiffness of the precursor nonwoven fabric may be expressed by the handle ometer test (HOM). During the test, the fabric is forcibly bent into a relatively small nip (6.2 mm wide, 8.0 mm deep). This is thought to be analogous to a filament bending around a pin. If the bending force is too small, the filament acts elastically and tends to return to its original position after hydropatterning, resulting in the hole being at least partially closed after hydropatterning. If the bending force is too large, the filament may break, and the free end of the filament may interfere with the hole, potentially reducing the clarity level of the hole. Furthermore, if the bending force is too large, the fabric resistance may prevent the pin from entering the structure, hindering hole formation.

[0181] According to an exemplary embodiment, the HOM value of the precursor nonwoven fabric 7 in the MD direction is at least 5 g.

[0182] According to an exemplary embodiment, the HOM value of the precursor nonwoven fabric 7 in the MD direction is a maximum of 30 g, preferably a maximum of 25 g.

[0183] In an exemplary embodiment, the HOM value of the precursor nonwoven fabric 7 in the CD direction is at least 2g.

[0184] According to an exemplary embodiment, the HOM value of the precursor nonwoven fabric 7 in the CD direction is a maximum of 20 g, preferably a maximum of 15 g.

[0185] According to an exemplary embodiment, the basis weight of the porous hydro-patterned nonwoven fabric 9 is 10 to 45 gsm, preferably 20 to 35 gsm.

[0186] According to an exemplary embodiment, the caliper of the porous hydro-patterned nonwoven fabric 9 is at least 12 microns / fabric 1 gsm.

[0187] According to an exemplary embodiment, the MD tensile strength of the porous hydro-patterned nonwoven fabric 9 is at least 4 N / cm.

[0188] According to an exemplary embodiment, the CD tensile strength of the porous hydro-patterned nonwoven fabric 9 is at least 2 N / cm.

[0189] According to exemplary embodiments, the porous hydro-patterned nonwoven fabric 9 is identical on both sides. This can be seen from Figures 13 and 14, which show macroscopic and magnified photographs of the fabric according to exemplary embodiments of the present invention. The porous hydro-patterned nonwoven fabric 9 is identical on both sides, at least in terms of physical and material properties.

[0190] In contrast, most conventional pore-forming techniques create three-dimensional or conical pores, resulting in the final fabric product having different surfaces on each side. For example, conventional heat-based techniques using needles / pins typically clearly show the side from which pore formation began, making the tactile feel of the pores less desirable (see Figure 15). The duality of conventional porous fabric products can hinder the performance of such products, as one side of the fabric may exhibit undesirable properties.

[0191] The porous hydro-patterned nonwoven fabric 9 according to an exemplary embodiment of the present invention exhibits a relatively high level of flexibility. This is at least partially due to the absence of sharp edges around the pores. This is in contrast to most prior arts that use heat to create openings in the fabric. It should be noted that flexibility itself is a very general term encompassing many different perceptions. Some of these perceptions may be expressed by measurements such as handle ometer, cantilever test, compressibility, thickness, coefficient of friction, and / or many other methods. Each test provides only a limited amount of information regarding flexibility, and that information may be suitable for certain applications, certain basis weight ranges, certain polymer compositions, etc.

[0192] The nonwoven fabric 9 may be incorporated into a nonwoven laminate. The nonwoven laminate may include an additional layer of continuous fibers such as spunbond fibers or meltblown fibers, or it may include a composite nonwoven fabric such as a spunbond-meltblown-spunbond laminate. The nonwoven laminate may also include short fibers such as staple fibers, or pulp fibers. These short fibers may be in the form of a compressed fabric such as worsted cloth or thin paper sheet, or they may not be compressed from the beginning. The nonwoven laminate may include superabsorbent material in either particulate or fibrous form. The laminate may be formed by conventional means such as thermal bonding, ultrasonic bonding, chemical bonding, adhesive bonding, and / or water entanglement, but is not limited to these. According to embodiments of the present invention, the fabric 9 may form a nonwoven laminate obtained from one or more of the above processes for use as a surface sheet, absorbent core, or backing sheet of an absorbent article.

[0193] The following examples and comparative examples illustrate the advantages of the present invention.

[0194] Comparative Example 1 (Precursor fabric for Example 1) A 25gsm spunmelt nonwoven vat was manufactured in a continuous process on a production line using a mixture of polypropylene (type 3155E5, Exxon) and a coloring additive (SCC 91056, Standridge Color), and a flexibility-enhancing additive based on ercamid (CESA-slip PP 42161, Avient). Here, single-component polypropylene filaments with fiber diameters of 13-25 μm were produced and then recovered on a moving belt. The vat was manufactured from four spunbond beams using REICOFIL 3.1 technology (Reifenhauser Reicofil, Troisdorf, Germany). The nonwoven vat was completely bonded using a pair of heated rollers. Here, one of the rollers had a raised pattern 3 (Figure 8). The temperature of the calendar roller (smooth roller / pattern roller) was 160°C / 162°C, and the bonding pressure was 75 N / mm. The resulting nonwoven fabric had the material properties shown in Table 2.

[0195] Example 1 The same nonwoven fabric as described in Comparative Example 1 was formed, but a hydro-patterning process was added. The hydro-patterning process was performed using two drums, with the last drum in the line forming holes in the fabric. The first drum had a wire mesh screen and two spraying devices positioned on the drum, with the water pressure applied by each spraying device as shown in Table 2. Before forming holes in the second drum, the fabric was hydro-treated using the first drum. Each spraying device had two rows of holes, spaced 0.6 mm apart from each other. The second drum had a screen with pins of the A1 pattern described herein (spaced 4.5 mm apart from each other). The fabric was hydro-patterned using three spraying devices applying the water pressure shown in Table 2, so as to create a hole pattern by pushing the fabric down onto the pins. Each of the three spraying devices on the second drum had two strips of holes, spaced 0.6 mm apart from each other. The pore formation process in Example 1 is summarized in Table 3. The resulting nonwoven fabric had the material properties shown in Table 2.

[0196] Comparative Example 2 (Precursor fabric for Example 2) A 25gsm spunmelt nonwoven vat was manufactured in a continuous process on a production line using a mixture of polypropylene (Mosten NB425, Unipetrol) and copolymer (Vistamaxx 6202, Exxon) in a weight ratio of 75:15, a coloring additive (SCC 91056, Standridge Color), and a softening additive based on erucamide (CESA-slip PP 42161, Avient). Here, single-component polypropylene filaments with fiber diameters of 13-25 μm were produced and then collected on a moving belt. The vat was manufactured from four beams using REICOFIL 3.1 technology. The nonwoven vat was completely bonded using a pair of heated rollers. Here, one roller had a raised pattern 3 (Figure 8). The temperature of the calendar roller (smooth roller / pattern roller) was 150°C / 155°C, and the bonding pressure was 75 N / mm. The resulting nonwoven fabric had the material properties shown in Table 2.

[0197] Example 2 The same nonwoven fabric as described in Comparative Example 2 was formed, but a hydro-patterning process was added. The hydro-patterning was performed using two drums, with the last drum in the line forming holes in the fabric. The first drum had a wire mesh screen and one spraying device positioned on the drum to apply a water pressure of 200 bar for hydro-treatment of the fabric before hole formation in the second drum. The one spraying device on the first drum had two rows of holes, with the holes in each band spaced 1.2 mm apart from each other. The second drum had a screen with pins of the A1 pattern described herein (the pins were spaced 4.5 mm apart from each other). The fabric was hydro-patterned using three spraying devices applying water pressures of 220 bar, 220 bar, and 250 bar, respectively, to create a hole pattern by pushing the fabric down onto the pins. Each of the three spraying devices on the second drum had two bands of holes, with the holes in each band spaced 0.6 mm apart from each other. The pore formation process in Example 2 is summarized in Table 3. The resulting nonwoven fabric had the material properties shown in Table 2.

[0198] Comparative Example 3 (Precursor fabric for Example 3) A 25gsm spunmelt nonwoven vat was manufactured in a continuous process on a production line from a mixture of polypropylene (type 3155E5, Exxon) and a coloring additive (SCC 91056, Standridge Color). Here, single-component polypropylene filaments with fiber diameters of 13–25 μm were produced and then collected on a moving belt. The vat was manufactured from four spunbond beams using the REICOFIL 3.1 technique. The nonwoven vat was completely bonded using a pair of heated rollers. One of the rollers had a raised pattern 2 (Figure 7). The temperature of the calendar roller (smooth roller / pattern roller) was 160°C / 162°C, and the bonding pressure was 75 N / mm. The resulting nonwoven fabric had the material properties shown in Table 2.

[0199] Example 3 The same nonwoven fabric as described in Comparative Example 3 was formed, but a hydro-patterning process was added. The hydro-patterning was performed using two drums, with the last drum in the line forming holes in the fabric. The first drum had a wire mesh screen and one spraying device positioned on the drum to apply a water pressure of 200 bar for hydro-treatment of the fabric before hole formation in the second drum. The one spraying device on the first drum had two rows of holes, with the holes in each row spaced 1.2 mm apart from each other. The second drum had a screen with pins of the A1 pattern described herein (the pins spaced 4.5 mm apart from each other). The fabric was hydro-patterned using three spraying devices applying water pressures of 220 bar, 220 bar, and 250 bar, respectively, to create a hole pattern by pushing the fabric down onto the pins. Each of the three spraying devices on the second drum had two rows of holes, with the holes in each row spaced 0.6 mm apart from each other. The pore formation process in Example 3 is summarized in Table 3. The resulting nonwoven fabric had the material properties shown in Table 2.

[0200] Comparative Example 4 (Precursor fabric for Example 4) A 25gsm spunmelt nonwoven vat was produced in a continuous process on a production line using a mixture of polypropylene (Mosten NB425, Unipetrol) and copolymer (Vistamaxx 6202, Exxon) in a weight ratio of 75:15, a coloring additive (SCC 91056, Standridge Color), and a softening additive based on erucamide (CESA-slip PP 42161, Avient). Here, single-component polypropylene filaments with fiber diameters of 13-25 μm were produced and then collected on a moving belt. The vat was produced from four beams using REICOFIL 3.1 technology. The nonwoven vat was completely bonded using a pair of heated rollers. Here, one roller had a raised pattern 2 (Figure 7). The temperature of the calendar roller (smooth roller / pattern roller) was 150°C / 155°C and the pressure was 75 N / mm. The resulting nonwoven fabric had the material properties shown in Table 2.

[0201] Example 4 The same nonwoven fabric as described in Comparative Example 4 was formed, but a hydro-patterning process was added. The hydro-patterning was performed using two drums, with the last drum in the line forming holes in the fabric. The first drum had a wire mesh screen and one spraying device positioned on the drum to apply a water pressure of 200 bar for hydro-treatment of the fabric before hole formation in the second drum. The one spraying device on the first drum had two bands of holes, spaced 1.2 mm apart from each other. The second drum had a screen with pins of the A1 pattern described herein (spaced 4.5 mm apart from each other). The fabric was hydro-patterned using three spraying devices applying water pressures of 220 bar, 220 bar, and 250 bar, respectively, to create a hole pattern by pushing the fabric down onto the pins. Each of the three spraying devices on the second drum had two bands of holes, spaced 0.6 mm apart from each other. The pore formation process in Example 4 is summarized in Table 3. The resulting nonwoven fabric had the material properties shown in Table 2.

[0202] Comparative Example 5 (Precursor fabric for Example 5) A 25gsm spunmelt nonwoven vat was manufactured on a production line in a continuous process from a mixture of polypropylene (type 3155E5, Exxon) and a coloring additive (SCC 91056, Standridge Color). Here, single-component polypropylene filaments with fiber diameters of 13–25 μm were produced and then collected on a moving belt. The vat was manufactured from four spunbond beams using the REICOFIL 3.1 technique. The nonwoven vat was completely bonded using a pair of heated rollers. One of the rollers had a raised pattern 1 (Figure 6). The temperature of the calendar roller (smooth roller / pattern roller) was 160°C / 162°C, and the bonding pressure was 75 N / mm. The resulting nonwoven fabric had the material properties shown in Table 2.

[0203] Example 5 The same nonwoven fabric as described in Comparative Example 5 was formed, but a hydro-patterning process was added. The hydro-patterning process was performed using two drums, with the last drum in the line forming holes in the fabric. The first drum had a wire mesh screen and one spraying device positioned on the drum to apply a water pressure of 200 bar for hydro-treatment of the fabric before hole formation in the second drum. The one spraying device on the first drum had two bands of holes, spaced 1.2 mm apart from each other. The second drum had a screen with pins of the A1 pattern described herein (spaced 4.5 mm apart from each other). The fabric was hydro-patterned using three spraying devices applying water pressures of 220 bar, 220 bar, and 250 bar, respectively, to create a hole pattern by pushing the fabric down onto the pins. Each of the three spraying devices on the second drum had two bands of holes, spaced 0.6 mm apart from each other. The pore formation process in Example 5 is summarized in Table 3. The resulting nonwoven fabric had the material properties shown in Table 2.

[0204] Comparative Example 6 (Precursor fabric to Example 6) A 25gsm spunmelt nonwoven vat was produced in a continuous process on a production line using a mixture of polypropylene (Mosten NB425, Unipetrol) and copolymer (Vistamaxx 6202, Exxon) in a weight ratio of 75:15, a coloring additive (SCC 91056, Standridge Color), and a softening additive based on erucamide (CESA-slip PP 42161, Avient). Here, single-component polypropylene filaments with fiber diameters of 13-25 μm were produced and then collected on a moving belt. Vats were produced from four beams using REICOFIL 3.1 technology. The nonwoven vats were completely bonded using a pair of heated rollers. Here, one roller had a raised pattern 1 (Figure 6). The temperature of the calendar roller (smooth roller / pattern roller) was 150°C / 155°C, and the bonding pressure was 75 N / mm. The resulting nonwoven fabric had the material properties shown in Table 2.

[0205] Example 6 The same nonwoven fabric as described in Comparative Example 6 was formed, but a hydro-patterning process was added. The hydro-patterning was performed using two drums, with the last drum in the line forming holes in the fabric. The first drum had a wire mesh screen and one spraying device positioned on the drum to apply a water pressure of 200 bar for hydro-treatment of the fabric before hole formation in the second drum. The one spraying device on the first drum had two rows of holes, with the holes in each band spaced 1.2 mm apart from each other. The second drum had a screen with pins of the A1 pattern described herein (the pins spaced 4.5 mm apart from each other). The fabric was hydro-patterned using three spraying devices applying water pressures of 220 bar, 220 bar, and 250 bar, respectively, to create a hole pattern by pushing the fabric down onto the pins. Each of the three spraying devices on the second drum had two bands of holes, with the holes in each band spaced 0.6 mm apart from each other. The pore formation process in Example 6 is summarized in Table 3. The resulting nonwoven fabric had the material properties shown in Table 2.

[0206] [Table 2]

[0207] [Table 3]

[0208] Comparative Example 7 (Precursor fabric for Example 7) A 35gsm spunmelt nonwoven vat was manufactured on a production line in a continuous process from a mixture of polypropylene (type 3155E5, Exxon) and a coloring additive (SCC 91056, Standridge Color). Here, single-component polypropylene filaments with fiber diameters of 13–25 μm were produced and then collected on a moving belt. The vat was manufactured from three spunbond beams using the REICOFIL5 technology. The nonwoven vat was completely bonded using a pair of heated rollers. One of the rollers had a raised pattern 3 (Figure 8). The temperature of the calendar roller (smooth roller / pattern roller) was 160°C / 162°C, and the bonding pressure was 75 N / mm. The resulting nonwoven fabric had the material properties shown in Table 4.

[0209] Example 7 The same nonwoven fabric as described in Comparative Example 7 was formed, but a hydro-patterning process was added. The hydro-patterning was performed using two drums, with the last drum in the line forming holes in the fabric. The first drum had a wire mesh screen and one spraying device positioned on the drum to apply a water pressure of 150 bar for hydro-treatment of the fabric before hole formation in the second drum. The one spraying device on the first drum had two rows of holes, with the holes in each band spaced 1.2 mm apart from each other. The second drum had a screen with pins (heart-shaped) of the Q5 pattern described herein. The fabric was hydro-patterned using three spraying devices applying water pressures of 220 bar, 220 bar, and 250 bar, respectively, to create a hole pattern by pushing the fabric down onto the pins. Each of the three spraying devices on the second drum had two bands of holes, with the holes in each band spaced 0.6 mm apart from each other. The pore formation process in Example 7 is summarized in Table 5. The resulting nonwoven fabric had the material properties shown in Table 4.

[0210] Comparative Example 8 (Precursor fabric for Example 8) A 25gsm spunmelt nonwoven vat was manufactured in a continuous process on a production line from a mixture of polypropylene (Mosten NB425, Unipetrol) and a coloring additive (SCC 91056, Standridge Color). Here, single-component polypropylene filaments with fiber diameters of 13–25 μm were produced and then collected on a moving belt. The vat was manufactured from three spunbond beams using REICOFIL4 technology. The nonwoven vat was completely bonded using a pair of heated rollers. One of the rollers had a raised pattern 1 (Figure 6). The temperature of the calendar roller (smooth roller / pattern roller) was 160°C / 162°C, and the bonding pressure was 75 N / mm. The resulting nonwoven fabric had the material properties shown in Table 4.

[0211] Example 8 The same nonwoven fabric as described in Comparative Example 8 was formed, but a hydro-patterning process was added. The hydro-patterning was performed using two drums, with the last drum in the line forming holes in the fabric. The first drum had a wire mesh screen and one spraying device positioned on the drum to apply a water pressure of 150 bar for hydro-treatment of the fabric before hole formation in the second drum. The one spraying device on the first drum had two rows of holes, with the holes in each band spaced 1.2 mm apart from each other. The second drum had a screen with pins (heart-shaped) of the Q5 pattern described herein. The fabric was hydro-patterned using three spraying devices applying water pressures of 220 bar, 220 bar, and 250 bar, respectively, to create a hole pattern by pushing the fabric down onto the pins. Each of the three spraying devices on the second drum had two bands of holes, with the holes in each band spaced 0.6 mm apart from each other. The pore formation process in Example 8 is summarized in Table 5. The resulting nonwoven fabric had the material properties shown in Table 4.

[0212] Comparative Example 9 (Precursor fabric to Example 9) A 25gsm spunmelt nonwoven vat was manufactured in a continuous process on a production line from a mixture of polypropylene (Mosten NB425, Unipetrol) and a coloring additive (SCC 91056, Standridge Color). Here, single-component polypropylene filaments with fiber diameters of 13–25 μm were produced and then collected on a moving belt. The vat was manufactured from three spunbond beams using REICOFIL4 technology. The nonwoven vat was completely bonded using a pair of heated rollers. One of the rollers had a raised pattern 3 (Figure 8). The temperature of the calendar roller (smooth roller / pattern roller) was 160°C / 162°C, and the bonding pressure was 75 N / mm. The resulting nonwoven fabric had the material properties shown in Table 4.

[0213] Example 9 The same nonwoven fabric as described in Comparative Example 9 was formed, but a hydro-patterning process was added. The hydro-patterning was performed using two drums, with the last drum in the line forming holes in the fabric. The first drum had a wire mesh screen and one spraying device positioned on the drum to apply a water pressure of 150 bar for hydro-treatment of the fabric before hole formation in the second drum. The one spraying device on the first drum had two rows of holes, with the holes in each band spaced 1.2 mm apart from each other. The second drum had a screen with pins (heart-shaped) of the Q5 pattern described herein. The fabric was hydro-patterned using three spraying devices applying water pressures of 220 bar, 220 bar, and 250 bar, respectively, to create a hole pattern by pushing the fabric down onto the pins. Each of the three spraying devices on the second drum had two bands of holes, with the holes in each band spaced 0.6 mm apart from each other. The pore formation process in Example 9 is summarized in Table 5. The resulting nonwoven fabric had the material properties shown in Table 4.

[0214] Comparative Example 10 (Precursor fabric to Example 10) 30 gsm spunmelt nonwoven vats were manufactured on a production line in a continuous process from 80:20 core / sheath bicomponent filaments. The core was formed from aliphatic polyester (PLA Ingeo 6100D, Nature Works), and the sheath was formed from aliphatic polyester with low melting point and crystallinity (PLA Ingeo 6752s, Nature Works) and a lubricant (Avient CR Bio 2144, Avient). Bicomponent filaments with fiber diameters of 15-30 μm were manufactured and then collected on a moving belt. Vats were manufactured from a single spunbond beam using REICOFIL4 technology. The nonwoven vats were completely bonded using a pair of heated rollers. One of the rollers had a raised pattern 1 (Figure 6). The temperature of the calendar rollers (smooth roller / pattern roller) was 140°C / 138°C, and the bonding pressure was 50 N / mm. The resulting nonwoven fabric had the material properties shown in Table 4.

[0215] Example 10 The same nonwoven fabric as described in Comparative Example 10 was formed, but a hydro-patterning process was added. The hydro-patterning was performed using two drums, with the last drum in the line forming holes in the fabric. The first drum had a wire mesh screen and one spraying device positioned on the drum to apply a water pressure of 100 bar for hydro-treatment of the fabric before hole formation in the second drum. The one spraying device on the first drum had two rows of holes, with the holes in each band spaced 1.2 mm apart from each other. The second drum had a screen with pins (heart-shaped) of the Q5 pattern described herein. The fabric was hydro-patterned using three spraying devices applying water pressures of 110 bar, 110 bar, and 120 bar, respectively, to create a hole pattern by pushing the fabric down onto the pins. Each of the three spraying devices on the second drum had two bands of holes, with the holes in each band spaced 0.6 mm apart from each other. The pore formation process in Example 9 is summarized in Table 5. The resulting nonwoven fabric had the material properties shown in Table 4. [Table 4]

[0216] [Table 5]

[0217] As shown in Table 2, each nonwoven fabric described in Examples 1-6 is improved in terms of thickness compared to the corresponding comparative example, with an average increase of at least 100%. Furthermore, it is noteworthy that the COF of each nonwoven fabric described in Examples 1-6 is significantly higher than that of the corresponding comparative example. In particular, when diapers are packaged together in a single package and multiple diapers are placed in close contact, textile processors such as diaper manufacturers generally prefer a higher COF to prevent slippage between diapers. Although the tensile strength of each nonwoven fabric described in Examples 1-6 is lower than that of the corresponding comparative example, it is noteworthy that each hydro-patterned nonwoven fabric described in Examples 1-6 provides hygiene product manufacturers with a unique fabric that is visually distinct and thicker while meeting normal product strength requirements and excellent abrasion resistance. Visual clarity is a function of the fiber modulus, which is due to the fiber composition and / or additives, and the bonding pattern and pin shape used to calendar-bond the precursor fabric. By superimposing a heat-bonded pattern while minimizing collisions with a hole-forming drum designed to form holes by fiber movement without softening additives in the fibers, a hydro-porous sample with the best visual clarity and abrasion performance was obtained. This is demonstrated by the fact that Example 3 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 calendar bonding shape.

[0218] It should be noted that the decrease in tensile strength of a fabric during hydrostatic treatment is not necessarily a critical parameter to evaluate. In the case of polyolefin fabrics, the decrease in tensile strength usually needs to be minimized as much as possible to meet the requirements of textile processors and the final product. In contrast, Example 10 shows a polyester fabric with relatively high tensile strength. Polylactic acid (PLA) nonwoven fabrics typically have high tensile strength, low elongation, and high HOM values. Hydrostatic treatment of PLA nonwoven fabrics according to the present invention can reduce the decrease in tensile strength to a relatively large level, close to that of polyolefin fabrics (MD -67%, CD -56%). However, it was more important that the index of flexibility (especially HOM) also decreased to a value quite close to the desired level of polyolefins (average (AVG) HOM decreased from 22.8 to 7.8), and that even the porous fabric was thicker compared to the precursor (generally, the thicker the fabric, the higher the HOM value). Furthermore, abrasion resistance remained high (close to 4 after hydrostatic treatment), and visual clarity was perfect.

[0219] While the above specification has described in detail specific embodiments of the present invention, it will be understood that many of the details provided herein may be substantially modified by those skilled in the art without departing from the spirit and scope of the invention.

[0220] Test method The tensile strength and elongation of nonwoven fabrics are measured using the test method in accordance with the NONWOVEN STANDARD PROCEDURES (WSP) 110.4.R4(12) standard. Tensile strength can also be expressed as "MDT" in the MD direction and "CDT" in the CD direction. Therefore, elongation can also be expressed as "MDE" in the MD direction and "CDE" in the CD direction.

[0221] The "handle ometer" or "HOM" stiffness evaluation of nonwoven fabric materials is performed using WSP test method 90.3 with some modifications. The "touch" quality is considered to be a combination of surface friction and bending stiffness of the sheet material. The equipment used in this test method is manufactured by Thwing Albert Instruments. In this test method, a 100 × 100 mm sample was used for HOM measurement, and the final reading obtained was recorded "as is" in grams, instead of doubling the reading according to WSP test method 90.3. The average HOM was obtained by taking the average of the MD value and the CD HOM value. Generally, a lower HOM value indicates higher softness and flexibility, while a higher HOM value indicates lower softness and flexibility of the nonwoven fabric.

[0222] The "thickness," "measurement height," or "caliper" of the nonwoven material shall be measured according to the European standard, the European Organization for Standardization standard (EN ISO) 9073-2:1995 (corresponding to method WSP120.6), and corrected in the following manner: 1. The material shall be measured using a sample taken from the manufacturing process. This measurement shall not involve applying high deformation forces for more than one day, nor subjecting it to pressure effects (e.g., pressure from rollers on the manufacturing equipment). Alternatively, it must be laid on the surface for at least 24 hours. 2. The total pressure applied during thickness measurement is 14.7 g / cm². 2 That is the case. 3. If there is a difference in thickness between the edge of the hole and the nonwoven fabric itself in the fabric, the value of the nonwoven fabric between the holes shall be taken as the measured value.

[0223] The "dynamic coefficient of friction" or "dynamic CoF" of nonwoven fabrics is measured using a Testing Machines 32-07 series friction tester in accordance with ASTM standard D1894. The reported data represents the dynamic coefficient of friction (CoF) between 10cm × 10cm nonwoven fabrics placed under a 200g warp. Here, the nonwoven fabric is pulled at a speed of 150mm / min, intersecting a 25cm × 10cm sample fixed as the same nonwoven fabric sample, while maintaining the consistency of the surface and orientation (A-sides together; MD-directions together).

[0224] "Visual clarity" was determined independently and visually by at least five people using the perforation clarity visual ranking index (see Figure 16). To record the evaluation, at least three of the five people (or at least three-fifths of the evaluation group) must perform the same evaluation for each fabric. Individual evaluations that do not match at least three other evaluations are not counted.

[0225] Wear evaluation: "Martindale Mean Abrasion Grade Test" or "Martindale" Figure 17 is a perspective view showing the apparatus for the Martindale Mean Abrasion Grade test. Specifically, Figure 18 shows the grade index for evaluating fuzziness in the Martindale Mean Abrasion Grade test.

[0226] The Martindale mean abrasion resistance rating of nonwoven fabrics is measured using a Martindale abrasion tester. The test is performed in a dry state. The nonwoven fabric sample is conditioned at a temperature of 23±2°C and a relative humidity of 50±2% for 24 hours. From each nonwoven fabric sample, cut out 10 circular samples with a diameter of 162 mm (6.375 inches). Cut out a circle of 140 mm in diameter from the reference felt. For each sample, the first cut felt is placed at each position on the Martindale test polishing stand, and then the next cut nonwoven fabric sample is secured. After that, a clamp ring is secured to prevent wrinkles from forming on the nonwoven fabric sample. Assemble the polisher holder. The polisher is made of 38mm diameter, 1 / 32 inch thick silicone rubber (McMaster-Carr part number 86045K21-50A), compliant with the U.S. Food and Drug Administration (FDA). Place the desired weights in the polisher holder so that a pressure of 9kPa is applied to the sample. Install the assembled polisher holder in model #864 so that the polisher is in contact with the nonwoven fabric (NW) sample, as instructed in the operator's guide. Perform Martindale wear under the following conditions: Mode: Abrasion test Speed: 47.5 cycles / minute Cycles: 80 cycles (unless otherwise specified) After the test is complete, the polished nonwoven fabric is placed on a smooth, matte black surface, and the level of fuzziness is graded using the index shown in Figure 17. Each sample is evaluated by observing both the dimensions and number of defects from above and the height of the defect protrusions from the side. A number from 1 to 5 is assigned to the sample that best matches each grade index. Next, the Martindale mean abrasion resistance grade is calculated as the average evaluation of all samples and reported as the closest grade on a 10-point scale.

[0227] The "adhesion area percentage" is determined by using ImageJ software (Vs.1.43u, National Institutes of Health, USA) to identify a single repeating pattern in the adhesive indentation and non-adhesion areas, and then zooming the image so that the repeating pattern fills the field of view. A frame is drawn in ImageJ to enclose the repeating pattern. The area of ​​the frame is calculated as 0.01 mm². 2 Record in increments. Next, use the area tool to completely trace each individual adhesive indentation or part thereof within the frame, and calculate the area of ​​all adhesive indentations or parts thereof within the frame. 0.01mm 2 Record in increments. Calculate as follows: Adhesion area percentage = (Total area of ​​adhesive indentations within the frame) / (Area of ​​the frame) × 100% Repeat the above procedure for all five non-adjacent regions of interest (ROIs) randomly selected across the entire specimen. Record the adhesive area percentage in 0.01% increments. Measurements are performed on both comparative and example specimens for each item. For each set of samples, measure a total of three identical items. Calculate the mean and standard deviation of the 30 percentage adhesive area measurements and report them in 0.001 increments.

Claims

1. A method for forming a porous hydro-patterned nonwoven fabric, comprising: A process for forming a nonwoven batt consisting of continuous spunmelt fibers; A step of calendar bonding the nonwoven vat to form a fully bonded precursor nonwoven fabric having a regular bonding pattern that defines individual bonding indentations and non-bonded areas between individual bonding indentations, wherein the bonding area of ​​the regular bonding pattern is 10% to 25% in percentage; and A step of imparting a plurality of holes to the aforementioned fully bonded precursor nonwoven fabric by water pressure, the step comprising treating the fully bonded precursor nonwoven fabric with water pressure by a plurality of water jets as the fully bonded precursor nonwoven fabric passes over a plurality of pins. A method characterized by comprising the following:

2. The method according to claim 1, wherein each of the pins has a base and a top, and the area of ​​the base is larger than the area of ​​the top.

3. The method according to claim 1, characterized in that the height of the pins is at least 100% of the thickness of the porous nonwoven fabric.

4. The method according to claim 1, characterized in that the nonwoven batt in the step of forming the preceding fabric consists of two or more layers.

5. The method according to claim 4, characterized in that, in the step of forming the preceding fabric, at least one of the two or more layers consists of spunbond filaments, and at least one of the other two or more layers consists of meltblown fibers.

6. The method according to claim 1, characterized in that, in the step of forming the precursor fabric, the continuous spunmelt fibers consist of a polyolefin, or a polyamide, or a polyester, or a polysaccharide homopolymer, or a copolymer or polymer blend thereof.

7. The step of forming the aforementioned preliminary fabric involves forming an adhesive indentation having an adhesive shape. The method according to claim 1, characterized in that the adhesive shape includes a convex portion, or includes a concave portion, or is asymmetrical.

8. The method according to claim 7, characterized in that the adhesive shape of the adhesive indentation is elliptical.

9. The method according to claim 7, characterized in that the adhesive shape of the adhesive indentation is linear.

10. The method according to claim 1, characterized in that the hydraulic treatment includes applying water pressure to the nonwoven precursor fabric using a water jet device.

11. The method according to claim 1, characterized in that the step of imparting a plurality of holes to the fully bonded precursor nonwoven fabric by water pressure includes at least partially altering each of the adhesive indentations by applying water pressure.

12. The method according to claim 11, characterized in that, by the step of at least partially changing the surface, at least 60% of the fully bonded portion of each adhesive indentation remains after the step of applying water pressure.

13. The method according to claim 11, characterized in that, by the step of at least partially changing, each of the adhesive indentations is divided into at least two parts.

14. The method according to claim 11, characterized in that, by the step of at least partially altering, the fibers in the region surrounding the outer edge of each adhesive indentation are randomly frayed inside and outside the main plane of the fully bonded precursor nonwoven fabric, and at least a portion of each adhesive indentation is no longer three-dimensional.

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