Method for making a hydroentangled nonwoven fabric and the fabric made thereby

Abstract

A process for making a single layer or multi-layer nonwoven material having improved cross-directional strength and feel, and the nonwoven material made thereby, is described. The process provides a nonwoven material including at least one layer formed of polymeric continuous filaments. The layer(s) are formed in a continuous sequential manner, i.e., a subsequent layer being formed on top of a preceding layer or layers. Thereafter, in the absence of any prebonding, the layer(s) are subjected to hydroentanglement. The basis weight of the nonwoven material is from about 17 to 150 gsm. The nonwoven material has improved properties based on treating the layer(s) by hydroentanglement. Varying the number of water jets and the pressure of the water allows variance in the properties obtained in the final product. Other physical properties can also be imparted to or changed in the nonwoven material by inclusion of an additive in a polymer melt during formation of the filaments, or by topical treatment following treatment of the layers of the nonwoven material by hydroentanglement.

Description

FIELD OF INVENTION

[0001] The invention is directed to a method for making a nonwoven material including forming at least one layer of continuous filaments and subjecting the layer(s) to hydroentanglement in the absence of any prebonding of the continuous filaments in the layer(s) prior to being subjected to hydroentanglement, as well as the nonwoven material made thereby. The nonwoven material has improved physical properties such as increased tensile and elongation properties, hand and drape, very low surface linting, etc. The nonwoven material provided is preferably spunlaid or meltblown or is a composite and can be present as a single layer or as one or more layers in a multi-layer nonwoven material. The material of the invention is in particular useful in personal care absorbent products, such as feminine hygiene products, diapers, adult incontinence products, etc., as well as for dry or wet wipes, medical products which come in contact with skin, and the like.

BACKGROUND OF THE INVENTION

[0002] Hydroentangled nonwoven webs and processes for making such webs are known in the art. In conventional processes, the process is usually limited by one or more critical parameters in order to provide a nonwoven product having a desired characteristic or quality dictated by the use to which the material is to be applied. In particular, prior art hydroentanglement processes require some type of prebonding of the filaments or fibers prior to being subjected to hydroentanglement. This adds to the time and cost of the process, but also affects the properties of the resulting nonwoven material, in particular as to the softness and durability of the material. Examples of known hydroentanglement processes are as follows:

[0003] U.S. Pat. No. 5,023,130 describes a process for water jet entangling continuous filament fibers to form a web wherein the combination of the water jet pressure and total impact energy provided by the water jets is controlling for producing a nonwoven web suitable for producing durable comfortable apparel. At column 4, lines 4-9, the patent teaches that “lightly consolidated webs” are suitable for use in the described process.

[0004] EP 0 333 211 B1 describe nonwoven fibrous hydraulically entangled web materials formed from a laminate of at least one layer of meltblown fibers and at least one layer of nonwoven fibrous material such as pulp fibers, staple fibers, meltblown fibers, continuous filaments, nets, foams, etc. Conventional hydraulic entangling techniques are disclosed as being suitable for use.

[0005] EP 0 333 228 B1 describes hydraulically entangled nonwoven fibrous material formed by entangling a coform of an admixture of non-elastic meltblown fibers and fibrous material.

[0006] U.S. Pat. No. 3,508,308 describes a jet treatment apparatus for producing entangled nonwoven fabrics involving supporting a layer of fibrous material on a smooth supporting member and subjecting the layer to multiple high pressure water jets. The layer of fibrous material is staple fibers or continuous filaments in the form of mats, batts, webs and the like, including layered composites or blends.

[0007] International Published Application WO 01/51693 A1 discloses an apparatus and method for continuously producing a multi-layer nonwoven fabric. The process involves sandwiching a first web of cellulosic fibers between two webs of spunlaid filaments. Consolidation of the resulting complex is then by hydroentanglement.

[0008] U.S. Pat. No. 5,801,107 describes a nonwoven fibrous material of pulp fibers which are loosened and rearranged by low energy jets of liquid so that the nonwoven material can absorb, transport and release liquid. The material is provided with a defined porosity.

[0009] U.S. Pat. No. 6,163,943 describes nonwoven material based on a foam-formed fibrous web, staple fibers and a layer of continuous filaments which are hydroentangled together to form a composite material.

[0010] International Published Application WO 01/53588 describes a nonwoven composite material made from at least one spunbonded woven fiber and wood pulp layer. The nonwoven fiber is compressed or calendered as a prebonding treatment prior to being subjected to hydrodynamic water needling.

[0011] U.S. Pat. No. 6,321,425 B1 describes a hydroentangled nonwoven fabric. The precursor web used to form the nonwoven fabric is subjected to compression and light bonding prior to hydroentanglement in order to facilitate handling of the web.

[0012] U.S. Pat. No. 5,151,320 describes a hydroentangled spunbonded composite fabric formed from a base web which is a prebonded web made from continuous filaments.

[0013] The conventional processes as known in the art produce nonwoven materials having strength in the tensile direction but not in the cross-direction. When the material is pulled in a cross-direction, the material will stretch and ultimately tear. Thus, a nonwoven material having both good tensile and cross-directional strengths is desirable, as well as a consolidated continuous process for producing such material. The ability to provide such improved material from a single raw material, in a continuous process in particularly being capable of pre-formation treatment or post-formation treatment to affect physical properties of the material, is desirable.

OBJECTS OF THE INVENTION

[0014] Accordingly, a primary object of the present invention is to provide a method for making a nonwoven material utilizing hydroentanglement as a means of bonding thereby eliminating the need for thermal bonding or chemical bonding agents, and a nonwoven material having improved strength.

[0015] More particularly, it is an object of the invention to provide a single layer or multi-layer nonwoven material having improved cross-directional strength made in a continuous in-line process wherein at least one layer of spunlaid or meltblown continuous filaments are bonded together by hydroentanglement in the absence of any prebonding such as by chemical, thermal compression, needling, calendering or the like.

[0016] It is a further object to provide a process for forming a nonwoven product from at least one layer of spunlaid or meltblown continuous filaments which require no prebonding treatment prior to being subjected to hydroentanglement by a plurality of high pressure water jets which can control the properties obtained in the resulting product.

[0017] It is a further object that the continuous filaments of each layer present are made from a thermoplastic polymer, preferably a polyolefin or polyester, and most preferably polypropylene.

[0018] A further object is to provide a nonwoven material with improved tensile and elongation properties, in particular increased strength in the cross-direction, so that the material is suitable for processing and use as a barrier for solids, such as superabsorbent polymers (SAPs) as used in diapers, adult incontinence products, feminine hygiene products and the like.

[0019] A further object is to alter one or more physical characteristics of the nonwoven material, such as the fluid handling property (e.g. hydrophobicity and hydrophilicity) of at least a portion of the nonwoven material, flame retardancy, absorbency, antistatic nature and the like, by incorporating one or more components into the nonwoven material, such as an additive added to an extruder polymeric melt or topical application to the resulting hydroentangled nonwoven material.

BRIEF DESCRIPTION OF THE INVENTION

[0020] A durable improved strength hydroentangled single layer or multi-layer nonwoven material is described. The nonwoven material is formed from at least one layer of continuous filaments, which are preferably spunlaid or meltblown, and the filaments are bonded by hydroentanglement in the absence of any prebonding of the filaments prior to being subjected to hydroentanglement. The filaments are preferably of a thermoplastic polymer, more preferably a polyolefin or polyester, and most preferably polypropylene. Certain properties of the nonwoven material, such as phobicity, philicity, flame retardancy, absorbency, antistatic nature, etc. can be imparted to or changed in the nonwoven material by including a suitable additive in the polymer to be extruded during production of the one or more layers of filaments, or by topically treating the resulting nonwoven material following hydroentanglement. For example, an additive or topical treating to affect hydrophilicity involves the use of a surfactant.

[0021] The process of the invention provides a nonwoven material having improved tensile and elongation properties as well as an improved hand. Notably the nonwoven material is provided with a cottony velveteen feel. The improved properties are obtained by provision of the spunlaid or meltblown layer(s) from continuous filaments in a continuous in-line process which includes hydroentangling the continuous filaments as part of the in-line process without any prebonding of the filaments. The process of the invention allows for the use of a single raw material, such as polypropylene, and avoids the necessity of using staple fibers. Staple fibers require a separate process of manufacture, interim storage and subsequent incorporation into another process to make a final product. Staple fibers were believed necessary for use in conventional processes to obtain hydroentangled fibers since it was believed necessary to have defined end structures to obtain the desired knotting during hydroentanglement to achieve bonding of the fibers. The process of the invention allows for the use of continuous filaments, thereby allowing for a continuous in-line process of production and treatment by hydroentanglement to join or bond the filaments together.

[0022] More in particular, a desired spunlaid or meltblown layer (or layers) is (are) produced by a conventional method for producing continuous filaments. The continuous filaments are laid onto a moving support, e.g. a moving mesh screen or a series of moving supports, e.g. perforated godet rollers. When a multi-layer material is being produced, second and subsequent layer(s) are laid sequentially upon the prior formed layer(s) on the moving support. The layer or layers then are subjected to hydroentanglement. No prebonding, e.g. by heat, compression, calendering, chemical or the like, is utilized. The moving support is structured to extend or transfer the layer or layers to the hydroentanglement equipment such that the layer(s) is essentially continually supported to the hydroentanglement apparatus. This serves to maintain the structure of the layer(s) and allow direct impact of water on the layer(s) from the plurality of high pressure water jets providing the hydroentanglement while avoiding flying apart of the layer(s) when the water hits the layer(s).

[0023] In the hydroentanglement process, a plurality of water jets are positioned above the moving support(s). The moving support(s) is preferably structured to allow for drainage of the water. The screen mesh or perforations in the godet rollers preferably have openings with a diagonal in the range of from about 0.1 to 2.0 mm. The number of water jets present and the pressure at which the water is ejected are critical in determining the properties obtained in the treated nonwoven material. The water jets are positioned so as to be spaced apart and provide about 50 water jets per linear inch. The water jets are arranged to cover the width of the layer(s) being treated. A single line or a plurality of lines of water jets may be used. The support(s) for the layer(s) moves at a speed generally in a range of about 20 to 250 meters per minute. Thus, adequate exposure to the water jets is provided. Water is fed under pressure through nozzles, preferably at a pressure of from about 20 to 250 bar. Nozzle orifice diameters can be from about 0.1 to 0.2 mm to provide the desired sized water streams. A preferred combination of number of water jets, pressure and orifice size is as follows: number of jets 25 to 50 per linear inch, pressure about 20 to 200 bar, and orifice size about 0.1 to 0.2 mm. If a material with looser filament structure is desired, the parameters are as follows: number of jets 25 to 50, pressure about 20 to 150 bar and orifice size about 0.1 to 0.2 mm. If a material with a tight filament structure is desired, the parameters are as follows: number of jets 30 to 50, pressure about 50 to 250 bar and orifice size about 0.1 to 0.2 mm.

[0024] The filament content of the nonwoven material is preferably of high density in order to prevent movement or migration of solids from one side to another of the material while at the same time allowing fluids to move through quickly based on additive or topical treatment with a surfactant. More particularly, the basis weight of the overall nonwoven material is preferably about 17 to 150 gsm (grams per square meter). In a multi-layer nonwoven material, each layer is preferably from about 8 to 80 gsm as to basis weight.

[0025] The hydroentangled nonwoven material will be hydrophobic when made from a thermoplastic polymer, such as polypropylene. To render the hydroentangled nonwoven material hydrophilic, which is a desired property in many conventional uses of nonwoven materials, a surfactant can be incorporated into the material. A suitable surfactant for use as an additive in a polymer melt is STANDAPOL™ 1353A or 1480, as sold by Cognis Deutschland GmbH, Dusseldorf, Germany, which are each a fatty ester. A preferred surfactant for topically treating the formed hydroentangled nonwoven material is STANTEX® S 6327, as sold by Cognis Deutschland GmbH, which is a blend of fatty acid esters. An example of a suitable topical treatment for imparting hydrophilicity to the nonwoven material is as described in U.S. Pat. Nos. 5,709,747 and 5,885,656, the disclosure of each patent being incorporated herein by reference. The surfactant is preferably present in the nonwoven material in an amount of from about 0.2 to 3.0 wt. %.

[0026] The nonwoven materials of the invention are useful in a wide variety of applications. For example, the nonwoven material is useful as a component of absorbent products such as disposable diapers, feminine hygiene products, adult incontinence products; medical products which contact the human skin such as surgical gowns and masks; disposable dry or wet wipes (both plain and impregnated dry wipes); industrial garments; filtration media; etc. The nonwoven material of the invention is in particularly well suited for those applications requiring both high strength and soft hand feel. The nonwoven material is also suitable for use as a barrier layer for retaining solids within a desired location, e.g., SAPs in diapers, adult incontinence products and feminine hygiene products. Continuous filament spunmelt webs subjected to water jet bonding have improved wet strength properties making the material in particularly useful in wet wipe applications, such as baby wipes, hard surface cleaning wipes, general purpose solution-containing wipes, specialty wipes having graphics applied thereto, and the like. Dry wipes include static dusting wipes or mops and wipes impregnated with a substance which is activated on addition to water.

[0027] The nonwoven material of the invention, following hydroentangling, further can be provided with a pattern, such as by conventional embossing or the like, to provide aesthtic appeal and/or enhancing fluid absorption, fluid retention, and fluid channeling characteristics in the nonwoven material.

BRIEF DESCRIPTION OF DRAWING

[0028] FIG. 1 is a schematic of a process for producing nonwoven material according to the invention.

[0029] FIG. 2 is a schematic of a preferred support for use during transfer and hydroentanglement and a positioning of water jets in relation thereto.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS

[0030] The hydroentangled nonwoven material provided by the process of the invention includes at least one layer of continuous filaments or fibers bonded by hydroentanglement in the absence of any prebonding of the filaments. The nonwoven material can be a single layer or multi-layer and include a combination of spunlaid and/or meltblown filament layer(s). The filaments forming the at least one layer are polymeric and continuous. The filaments can be made using conventional extrusion apparatus and techniques. The invention avoids the use of staple fibers. Preferably when a single layer, the nonwoven material is spunlaid. The hydroentangled nonwoven material of the invention has a superior tensile and elongation properties as compared to hydroentangled nonwoven materials made from staple fibers.

[0031] To provide a nonwoven material with high strength in the machine direction and cross-direction as well as having improved processability, both during manufacture and after manufacture, the hydroentangled nonwoven material preferably has a basis weight of about 17 to 150 gsm. More preferably the nonwoven layer has a basis weight of from about 25 to 100 gsm, most preferably from about 30 to 70 gsm.

[0032] The filaments of the layer(s) is (are) made of a thermoplastic polymer. Suitable polymers include polyolefins such as polypropylene and polyethylene; polyesters such as polyethylene terephthalate; polyamides; polyacrylates; polystyrene; thermoplastic elastomers; and blends of these and other known fiber forming thermoplastic materials. The preferred useful polymer is polypropylene. If the nonwoven material is multi-layer, each layer is preferably of the same polymeric material. The process of the invention is advantageous for providing improved physical properties while using one raw material and an in-line continuous process to obtain the desired product.

[0033] The denier size of the filaments is effective to alter physical properties of the resulting material. Preferably the denier size is about 0.8-5 dpf to provide a nonwoven material of desired strength.

[0034] Various physical properties, such as hydrophilicity, can be imparted to at least one portion of or completely to the hydroentangled nonwoven material depending on the use to which the nonwoven material is to be applied. At least one portion of the nonwoven material includes where one or more layers in their entirety are modified as to a given property, or any preselected portion or one or more of the layers have a preselected area thereof modified as to a preselected property. The manner of imparting a particular property to the nonwoven material can be based on the inclusion of an additive in the polymer melt or by topical treatment. This will be further evident from the description below of the method of making the nonwoven material. Properties which can be affected include fluid phobicity, fluid philicity, fire retardancy, absorbency, softness, antistatic nature, etc.

[0035] The method of the invention for making a nonwoven material will be described in relation to the figures. An advantage of the method of the invention is the provision of a single layer or multi-layer nonwoven material in a process which combines the manufacture of continuous thermoplastic polymer filaments, the formation of a layer therefrom and, if desired, the combining of multiple layers, and thereafter treating along the same processing line, without any prebonding of the filaments, of the layer or layers with a plurality of water jets to provide a bonded nonwoven material with improved strength and feel. This improves on conventional multi-stage processes wherein staple fibers are made by a first process, stored and subsequently used to form a product in a separate process, or a first layer is made and then processed for storage or use in another process. The conventional processes require multiple lines and stages which necessarily include lost or down time between processing stages. The invention provides for a consolidated continuous process in terms of space, time, material storage, etc. Additionally, savings are achieved by not requiring prebonding equipment or processing prior to hydroentanglement.

[0036] With reference to FIG. 1, a moving support 1 (which can be a belt, mesh screen, or the like) moving continuously along rollers 3 is provided beneath the exit orifices for one or more extruders, illustrated for example as extruders 5, 7 and 9. Extruder 5 receives a polymeric melt which is extruded through a substantially linear diehead 11 to form a plurality of continuous filaments 13 which randomly fall to the moving support 1 to form a layer 15, preferably, of spunlaid fibers thereon. The extrusion process parameters used are conventional and as known to one skilled in the art. The diehead includes a spaced array of die orifices having diameters of preferably about 0.1 to about 1.0 millimeters (mm). The continuous filaments following extrusion are quenched, such as by cooling air.

[0037] Positioned downstream in relation to the moving support 1 in the processing direction can be additional extruders, 7 and/or 9 for example, for providing continuous filaments 17 and/or 21, which can be, for example, spunlaid or meltblown. Extruders 7 and 9 can make additional continuous filaments as described in relation to continuous filaments 13. Filaments 17 and 21 randomly fall to moving support 1 and are laid atop a preceding deposited layer to form superposed layers 19 and 23, respectively. Thus, if desired, along one continuous line a multi-layer nonwoven material can be provided using continuous filaments.

[0038] The single layer or stacked layers are then joined or bonded together to form a coherent material by hydroentanglement utilizing a plurality of water jets 25 such as illustrated in FIGS. 1 and 2. Prebonding, such as conventional compression, thermal bonding, calendering or the like, of the layer(s) together to provide interlocking of the filaments is not required. Hydroentanglement therefore is conducted in the absence of conventional processes such as thermal bonding, chemical bonding, adhesive bonding, mechanical punch needling and the like, to provide a nonwoven material having acceptable physical properties, and in fact superior tensile and elongation properties as compared to nonwoven materials based on hydroentangled staple fibers.

[0039] The process of the invention provides hydroentanglement of continuous filaments. In conventional processes of hydroentanglement, staple fibers are used in order to provide free end structures capable of providing knotting upon being subjected to water jets. Conventional processes provide nonwoven material which have adequate strength in the tensile direction but not in the cross-direction. Thus, upon being subjected to stretching, conventional nonwoven materials will tear. The present invention provides for hydroentanglement of continuous filaments resulting in a finished product with improved cross-directional strength and improved feel. The finished product has a cottony velveteen feel. Further, the raw material used can be the same for each layer present in the product. This additionally results in a very economic process and thus economically advantageous product. If desired, other filaments or pulp can be added to further enhance the improved properties. However, such are not required. The continuous filaments utilized can have a variety of deniers, e.g., preferably about 0.8-5 dpf, and/or bicomponent filaments to further alter the physical properties of the nonwoven material. Deniers of about 0.8 to 5 dpf are preferred to enhance the properties of softness and uniformity.

[0040] The hydroentanglement process of the invention involves moving the formed layer or layers along moving support 1 to the hydroentanglement station 27. A transfer belt 29 and godet rollers 33, or other equivalent structures, serve to essentially maintain the layer(s) on a support surface so that when the layer(s) are hit with water from the water jets, the filaments do not fly apart. FIG. 2 illustrates a preferred embodiment of hydroentanglement according to the present invention. The single layers or stack of layers is indicated at 28 which moves to a transfer belt 29 moving around rollers 31. From transfer belt 29, the layer(s) move along godet rollers 33. Godet rollers 33 will have a screen which allows for the passage of water therethrough for drainage. Water jets are depicted at 25. Initial water jet treatment can begin in relation to transfer belt 29. Other water jets 25 are spaced in relation to godet rollers 33 in order to meet the parameters as more specifically described below. The resulting hydroentangled nonwoven material 35 is then transported by means of tension roller 36 for subsequent treatments as desired, e.g. topical treatment, drying, winding, embossing, etc. The support which passes beneath the water jets is preferably a series of moving supports. Perforated godet rollers, as illustrated in FIG. 2, preferably have openings with a diagonal of from about 0.1 to about 2.0 mm. This allows for good support and drainage of the water. Drainage can be simply obtained by gravity feed or else by utilization of a vacuum box or by other conventional structures.

[0041] The ability to determine and control the properties obtained in the nonwoven material is based on the number of water jets present, and the pressure of the water ejected from the water jets and applied to the nonwoven material. Water jets are present in number so as to provide from 25 to 50 water jet streams per linear inch of nonwoven material with the water being ejected at a pressure of from about 20 to about 250 bar. The orifice of the water jet nozzles are preferably from about 0.1 to about 0.2 mm in diagonal. The layer(s) preferably move at a speed of from about 20 to about 250 meters per minute while being subjected to the water jets. The water jets preferably are positioned over the nonwoven material being treated and in one or more lines extending across the width of the layer(s) being processed at essentially a right angle to the direction of advance of the layer(s).

[0042] As above described, the number of water jets and the pressure utilized can be varied so as to provide nonwoven material having different qualities. Examples of different operating parameters which can be used during hydroentanglement and the different physical properties affected and final product provided are described below. 1 TABLE 1 LIQUID ABSORPTIVE CAPACITY Dimensions of Test Piece: 100 × 100 mm Liquid: Water Liquid Dry Wet Absorptive Material Type Mass (g) Mass (g) Capacity (Wa) Treatment 60 gsm (1.4 den) 1.258 9.288 635.0% Cognis 1480 1.305 9.679 1.320 9.671 1.300 9.278 1.288 9.643 60 gsm (2 den) 1.308 9.299 595.4% Cognis 1480 1.324 9.418 1.327 8.891 1.306 8.655 1.297 9.367 60 gsm (2 den) 1.325 10.5 663.1% Cognis 1480 Patterned 1.300 9.73 “Dots” 1.253 9.194 1.309 10.200 1.298 9.865 50 gsm 1.040 8.786 737.6% Cognis 1480 (1.4 den) 1.075 8.911 1.035 8.626 1.049 8.723 1.028 8.736 50 gsm (2 den) 1.082 8.659 695.7 Cognis 1480 1.099 8.793 1.095 8.479 1.094 8.761 1.076 8.643 50 gsm 1.140 11.709 848.9% Cognis 1480 (1.4 den) 1.152 10.387 Patterned 1.142 10.460 “Waves” 1.099 10.167 1.129 11.002

[0043] 2 TABLE 2 LIQUID ABSORBENCY TIME Dimensions of Test Piece: 100 × 100 mm Liquid: Water Liquid Average Liquid Absorbency Absorbency Material Type Time (Sec.) Time (Sec.) Treatment 60 gsm (1.4 den) 2.83 3.02 Cognis 1480 2.95 3.28 60 gsm (2d en) 2.81 3.04 Cognis 1480 3.43 2.88 60 gsm (2 den) 3.10 3.20 Cognis 1480 Patterned “Dots” 3.29 3.20 50 gsm (1.4 den) 4.38 4.47 Cognis 1480 4.61 4.43 50 gsm (2 den) 4.64 4.62 Cognis 1480 4.94 4.27 50 gsm (1.4 den) 14.68 13.34 Cognis 1480 Patterned “Waves” 10.69 14.65

[0044] 3 TABLE 3 LIQUID WICKING RATE Dimension of Test Piece: 100 × 100 mm Liquid: Water Average Type of Sample 1 Sample 2 Sample 3 Sample 4 Sample 5 Capillary Material Time (Sec) (mm) (mm) (m) (m) (m) Rise 60 gsm MD 10 20 18 17 18 16 17.8 (1.4 den) 30 29 28 26 24 22 25.8 60 32 33 30 31 29 31.0 60 gsm MD 10 20 19 17 18 17 18.2 (2 den) 30 25 27 24 22 23 24.2 60 31 33 30 30 31 31.0 60 gsm MD 10 20 21 21 21 22 21.0 Patterned 30 28 27 26 27 28 27.2 “Dot” 60 34 35 32 33 35 33.8 50 gsm MD 10 5 8 4 3 5 5.0 (1.4 den) 30 8 11 6 5 9 7.8 60 12 14 9 8 12 11.0 50 gsm MD 10 10 11 11 12 10 10.8 (2 den) 30 15 16 15 16 13 15.0 60 18 19 19 18 17 18.2 50 gsm MD 10 5 4 5 4 5 4.6 (1.4 den) 30 10 8 9 9 8 8.8 “Waves” 60 12 10 12 11 11 11.2

[0045] 4 TABLE 4 TENSILE STRENGTH Tensile Tensile Strength Elongation Strength Elongation Type of Material MD (N/5 cm) MD (%) CD (N/5 cm) CD (%) 60 gsm (1.4 den) 209.1 106.3 153.6 136.9 60 gsm (2 den) 205.06 100.5 150.6 131.8 60 gsm (2 den) 194.4 112.7 153.7 131.9 Patterned “Dots” 50 gsm (1.4 den) 169.2 101.2 119.4 122.8 50 gsm (2 den) 163.7 89.3 118.5 132.6 50 gsm (1.4 den) 144.5 96.0 113.5 115.9 Patterned “Waves”

[0046] Physical properties (e.g., fluid phobicity, fluid philicity, fire retardancy, absorbency, antistatic nature, etc.) can be imparted to or changed in the nonwoven material in different ways. For example, subsequent to hydroentanglement and dehydration of the layer(s), the nonwoven material can be subjected to topical treatment 37, such as described in U.S. Pat. Nos. 5,709,747 and 5,885,656 which are incorporated herein by reference. As described therein, topical treatment can be to preselected areas depending on the use to which the nonwoven material will be applied. For example, if used in the manufacture of a diaper, a central areal portion may be treated with a surfactant to impart a hydrophilic character thereto. For example, to affect hydrophilicity, a surfactant can be used, such as STANTEX® S 6327, as sold by Cognis Deutschland, GmbH, Dusseldorf Germany, which is a blend of fatty acid esters. The surfactant is a liquid suitable for topical application to the nonwoven material. Other examples of surfactants suitable for use include PPH 53 as sold by Dr. Bohme GmbH, Germany; and PP 842 as sold by Uniquema, United Kingdom.

[0047] Alternatively, physical properties can be imparted to or changed in the nonwoven material by providing a suitable additive to the extrusion polymeric melt fed to one or more of extruders 5, 7 and/or 9. A suitable surfactant additive to affect hydrophilicity is STANDAPOL™ 1353A or 1480, sold by Cognis Deutschland, GmbH, which each are a fatty ester(s). These additives maybe present in either liquid or granular form. Other examples of surfactants suitable for use include PPH 53 as sold by Dr. Bohme GmbH, Germany; and PP 842 as sold by Uniquema, United Kingdom. Whether a surfactant additive is fed to one or more of extruders 5, 7 and/or 9 depends on the characteristics of the nonwoven material desired. For example, whether a complete strike through of liquid is desired or only a partial strike through is desired.

[0048] A surfactant is preferably present in an amount of about 0.2-3.0% by weight of the nonwoven material when the nonwoven is hydrophobic and is to be rendered hydrophilic.

[0049] Other properties of the nonwoven material can be affected, such as fire retardency, absorbency, antistatic nature and the like, by additive or topical application of an appropriate modifying component as described above with regard to affecting the hydrophobic property of the nonwoven material.

[0050] Following hydroentanglement, and topical treatment if carried out, the nonwoven material is subjected to conventional drying and winding so as to provide a finished product ready for use.

[0051] Also following hydroentanglement, the resulting nonwoven material can be subjected to embossing or other conventional process to provide a pattern to the nonwoven material. The pattern can provide aesthetic appeal and/or enhance certain physical properties, for example fluid absorption, fluid retention and fluid channeling or direction control of fluid upon contact with the material to control the site of absorption.

[0052] As will be apparent to one skilled in the art, various modifications can be made within the scope of the aforesaid description. Such modifications being within the ability of one skilled in the art form a part of the present invention and are embraced by the appended claims.

Claims

1. Process of forming a nonwoven material comprising

providing continuous thermoplastic polymer filaments;

laying the continuous filaments upon a moving support to provide at least one layer on said support;

joining the continuous filaments of the at least one layer together by hydroentangling the filaments in absence of prebonding of the filaments forming said at least one layer,

wherein said hydroentangling is provided by subjecting said at least one layer to water emitted at a pressure of from about 20 to about 250 bar from a plurality of water jets with at least 25 water jets per linear inch of planar surface of said at least one layer.

2. Process according to claim 1 wherein said polymer is a polyolefin.

3. Process according to claim 2 wherein said polymer is polypropylene.

4. Process according to claim 1 wherein said polymer is a polyester.

5. Process according to claim 1 further comprising, following said hydroentangling, topically treating said at least one layer with an additive to impart to or change a physical property in said at least one layer.

6. Process according to claim 1 further comprising incorporating an additive in said continuous thermoplastic polymer filaments to impart to or change a physical property of said filaments.

7. Process according to claim 5 wherein said additive renders said nonwoven material at least in part lyophobic, lyophilic, fire retardant, antistatic, and/or absorbent.

8. Process according to claim 6 wherein said additive renders said nonwoven material at least in part lyophobic, lyophilic, fire retardant, antistatic, and/or absorbent.

9. Process according to claim 1 wherein said at least one layer is spunlaid or meltblown.

10. Process according to claim 1 wherein said water jets have nozzle orifices ranging from about 0.1 to about 0.2 mm in diameter.

11. Process according to claim 1 wherein said at least one layer is supported on a series of perforated godet rollers during said hydroentangling.

12. Process according to claim 1 wherein said continuous filaments are provided at a denier of from about 0.8-5 dpf.

13. Process according to claim 1 further comprising, following said hydroentangling, providing a pattern on said nonwoven material.

14. A nonwoven material made according to the process claimed in any one of claims 1 to 13.