CA2624808A1

CA2624808A1 - Nonwoven fabric, articles including nonwoven fabrics, and methods of making nonwoven fabrics

Info

Publication number: CA2624808A1
Application number: CA002624808A
Authority: CA
Inventors: John A. Wolhar; Michael E. Kazmierczak; Carl J. Wust, Jr.; Prashant Desai; Charlie B. Allen; Gregory A. Jackson
Original assignee: Individual
Current assignee: Fibervisions Lp
Priority date: 2005-10-03
Filing date: 2006-10-03
Publication date: 2007-04-12
Also published as: BRPI0616733A2; CN101258029A; WO2007041620A8; JP2009510278A; MX2008004048A; EP1931512A4; EP1931512A1; KR20080088571A; WO2007041620A1; CN101258029B

Abstract

Briefly described, embodiments of this disclosure include nonwoven fabrics, methods of making nonwoven fabrics, articles including nonwoven fabric, and the like.

Description

NONWOVEN FAB~JP.S_.,.ARTICLES INCLUDING NONWOVEN FABRICS, ANU
METHODS OF MAKING NONWOVEN FABRICS

CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority to U.S. provisional application entitled, "Bulky/Extensible Fabric," having serial number 60/723,197, filed on October 3rd, 2005, which is entirely incorporated herein by reference.

FIELD OF THE INVENTION(S) The present disclosure relates to nonwoven fabrics in general and nonwoven fabrics that exhibit higher bulk properties.

BACKGROUND
The requirements of nonwoven fabrics used in applications concerned with hygiene, medical fabrics, wipes, and the like continue to grow. Moreover, utility, economy, and aesthetic qualities often must be met simultaneously. The market continues to expand for polyolefin fibers and items made therefrom having enhanced properties and improved softness or bulk.
The production of polymeric fibers for nonwoven materials usually involves the use of a mix of at least one _polymer with nominal amounts of additives, such as stabilizers, pigments, antacids and the like. The mix is melt extruded and processed into fibers and fibrous products using conventional commercial processes.
Nonwoven fabrics can be produced by making a web, and then thermally bonding the fibers together. For example, staple fibers are converted into nonwoven fabrics using, for example, a carding machine, and the carded fabric is thermally bonded.
The thermal bonding can be achieved using various heating techniques, including heating with heated rollers, hot air, and heating through the use of ultrasonic welding.
Fibers can also be produced and consolidated into nonwovens in various other manners. For example, the fibers and nonwovens can be made by the spunbonding or meltblowing processes or a combination thereof. Also, consolidation processes can include needlepunching, through-air thermal bonding, ultrasonic welding and hydroentangling.

ManX nonwoven fabrics, such as conventional thermally bonded nonwoven .
fabrics, do not exhibit sufficient bulk or extensibility for certain end uses.
Therefore, a need exists for nonwoven fabrics that exhibit sufficient bulk and extensibility.

SUMMARY
Briefly described, embodiments of this disclosure include nonwoven fabrics, methods of making nonwoven fabrics, articles including nonwoven fabric, and the like.
An embodiment of a fabric, among others, includes a nonwoven fabric having at least a first fiber and a second fiber. The first fiber has a first fiber shrinkage percent and the second fiber has a second fiber shrinkage percent. The difference in the first fiber shrinkage percent and the second fiber shrinkage percent is at least 8%.
An embodiment of a fabric, among others, includes a nonwoven fabric having at least a first domain of shrinkage and a second domain of shrinkage. The first domain and the second domain define differentiated domains of shrinkage. The nonwoven fabric includes at least a first fiber and a first shrinking fiber.
An embodiment of an article, among others, includes a nonwoven fabric as described herein, where the article is selected from a cleaning wipe, a diaper, a textile stretch component, an incontinence care product, a feminine care product, and a filter.
An embodiment of a method of forming a nonwoven fabric, among others, includes: providing a nonwoven fabric including a first fiber and a second fiber, wherein the first fiber has a first fiber shrinkage percent and the second fiber has a second fiber shrinkage percent, wherein the difference in the first fiber shrinkage percent and the second fiber shrinkage percent is at least 8%; forming at least a first domain of shrinkage and a second domain of shrinkage, wherein the first domain and the second domain define differentiated domains of shrinkage, wherein a portion of the first fiber and a portion of the second fiber in the first domain are bonded; and heating the nonwoven fabric to an activation temperature of the second fiber, wherein the second fiber shrinks and causes the first fiber to gather to increase the thickness of the nonwoven fabric in the second domain.

,Anem4odime,n#,õQf a,RX,pethod of forming a nonwoven fabric, among others, includes: providing a nonwoven fabric including a first fiber and a second fiber, wherein the first fiber has a first fiber shrinkage percent and the second fiber has a second fiber shrinkage percent, wherein the difference in the first fiber shrinkage percent and the second fiber shrinkage percent is at least 8%; and heating the nonwoven fabric to an activation temperature of the second fiber, wherein the second fiber shrinks and causes the first fiber to gather to increase the thickness of the nonwoven fabric.

BRIEF DESCRIPTION OF THE DRAWINGS
Many aspects of the disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being,placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.
FIGS. 1A and 1 B illustrate graphs of a shrinking fiber (FIG. 1A) and a non-shrinking fiber (FIG. I B).
FIGS. 2A and 2B illustrate photomicrographs of cross sectional views of nonwoven webs of the present disclosure. FIG. 2A illustrates an embodiment of a nonwoven web used for producing the bulky nonwoven fabric that has not been activated by a thermal bulking step. FIG. 2B illustrates the nonwoven web that has been activated to produce the bulky nonwoven web.
FIG. 3 illustrates Table 1, which describes a number of embodiments of nonwoven fabrics of the present disclosure.

DETAILED DESCRIPTION
Embodiments of the present disclosure will employ, unless otherwise indicated, techniques of textiles, chemistry, and the like, which are within the skill of the art. Such techniques are explained fully in the literature.
The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to perform the methods and use the compositions and compounds disclosed and claimed herein. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, tem,neratu,re,,..~õerrors and deviations should be accountea tor. uniess indicated otherwise, parts are parts by weight, temperature is in C, and pressure is at or near atmospheric. Standard temperature and pressure are defined as 25 C
and I atmosphere.
Before the embodiments of the present disclosure are described in detail, it is to be understood that, unless otherwise indicated, the present disclosure is not limited to particular materials, reagents, reaction materials, manufacturing processes, or the like, as such can vary. It is also to be understood that the terminology used herein is for purposes of describing particular embodiments only, and is not intended to be limiting. It is also possible in the present disclosure that steps can be executed in different sequence where this is logically possible.
It must be noted that, as used in the specification and the appended claims, the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "a support"
includes a plurality of supports. In this specification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings unless a contrary intention is apparent.
It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed herein in a range format. It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. To illustrate, a concentration range of "about 0.1% to 5%"
should be interpreted to include not only the explicitly recited concentration of about 0.1 wt%
to about 5 wt%, but also include individual concentrations (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.5%, 1.1%, 2.2%, 3.3%, and 4.4%) within the indicated range.

Definitions In describing and claiming the disclosed subject matter, the following terminology will be used in accordance with the definitions set forth below.

The term "n,cnuvQU,e,n,','.,.fabric, sheet, or web as used herein means a textiie structure of individual fibers, filaments, or threads that are directionally or randomly oriented and interact with one another by friction, and/or cohesion, and/or adhesion, as opposed to a regular pattern of mechanically inter-engaged fibers (e.g., it is not a woven or knitted fabric). Examples of nonwoven fabrics and webs include, but are not limited to, carded webs, spunbond continuous filament webs, meltblown webs, air-laid webs, and wet-laid webs. Suitable bonding methods include thermal bonding, chemical or solvent bonding, resin bonding, mechanical needling, hydraulic needling, stitch-bonding, combinations thereof, and the like. An illustrative, nonlimiting embodiment of the present disclosure includes carded thermal bond nonwoven fabrics.
The terms "bonded" or "bonding" are used herein to describe areas of a nonwoven fabric having inter-fiber bonding or entanglement beyond which occurs in nonwoven fabrics.
The term "bulk" or "loft" is used as an indication of the bulk specific volume of the nonwoven for a given areal density. The terms "bulk" and "loft" are generally used interchangeably. As such, the term "bulk" is used to describe both "bulk"
and "loft". Bulk specific volume can be obtained by dividing the bulk volume of a nonwoven sample by its mass. A bulky nonwoven is relatively less dense rather than compressed. Areal density is mass per unit area and is generally reported as grams per square meter (gsm). Areal density is often referred to as "basis weight"
and the terms are equivalent.
The terms "shrink", "shrinkage", "shrinking" as used in reference to fibers refers to the reduction in the length of the fiber as measured by thermomechanical analysis (TMA). A typical instrument for measuring shrinkage is the Model Q400, made by TA Instruments. A discussion of shrinkage can be found in "Thermal Characterization of Polymeric Materials", Academic Press (1981) pp. 736-743, which is incorporated herein by reference. FIGS. 1A and 1 B illustrate graphs of a shrinking fiber and a non-shrinking fiber.
The term "extensibility" as used in reference to nonwoven fabrics refers to the ability of the fabric to exhibit large elongation upon application of stress.
The term "elasticity" refers to the ability of an extensible nonwoven to return essentially to its pre-stressed state upon release of the stress.

The,terKp ",aQtiuq,4o,rl'õ,refers to a process used to increase bulk subsequent to the formation of the nonwoven fabric.

General Discussion Briefly described, embodiments of this disclosure include nonwoven fabrics, methods of making nonwoven fabrics, articles including nonwoven fabric, and the like. The nonwoven fabric of the present disclosure have improved effects (e.g., increased bulk, adjustable textural feel, improved foreign particle entrapment, increased areal density, and the like) as compared to other nonwoven fabrics.
In addition, the nonwoven fabrics are highly extensible relative to other nonwoven fabrics. The degree of extensibility is dependent on the activation temperature, fabric construction, bonding pattern, and the like. Under some conditions, a degree of elasticity may also be present which in turn, is dependent on the activation temperature, fabric construction, bonding pattern, and the like.
The nonwoven fabrics can be included in articles such as, but not limited to, cleaning wipes, diapers, textile stretch components, incontinence care products, feminine care products, filters, felts, and the like. The nonwoven fabrics can be used in articles in the landing zones, in the acquisition/distribution layers, stretch ears, topsheet, backsheet, and the like.
The nonwoven fabrics can be tailored to have a pre-determined bulk, a certain softness/harshness, areal density, and the like, by selecting components of the nonwoven fabric (e.g., fibers), parameters for treating the nonwoven fabric, bonding patterns, and the like. In other words, the nonwoven fabric can be designed for many applications such as, but not limited to, cleaning surfaces (e.g., soft surface or rough surface); acquiring, distributing or delivering liquids; adding comfort, filtering liquids, gases or powders; acoustic attenuation; and/or combinations thereof.
In general, the nonwoven fabric includes one or more nonwoven layer(s), where the nonwoven layer(s) includes at least a first fiber and a second fiber. The first fiber and the second fiber have different levels or rates of shrinkage under certain conditions (e.g., activation temperature and time to shrink the fibers, and degree of constraints against dimensional change). Upon activation, the second fiber shrinks, and as the second fiber shrinks in size it pulls some first fibers with it to produce one or more areas of increased bulk.

Thp,lp,gpwgu~~,,f~~;~r~c~~an increase in bulk by about 20 to 500 %, about 3U
to 450 %, and about 50 to 350 % relative to the bulk of the unactivated nonwoven fabric. The nonwoven fabric can increase in thickness by about 30 to 650 %, about 45 to 550 %, and about 60 to 500 % relative to the thickness of the unactivated nonwoven fabric.
The activation conditions (e.g., temperature and time or degree of constraints against dimensional change) applied to the nonwoven fabric depend, at least in part, upon the fiber composition, the amount of shrinkage desired, the textural feel (e.g., from soft to rough) of the nonwoven fabric desired, the amount of bulkiness desired, the level of extensibility and elasticity desired, and the like. The activation of the fibers in nonwoven fabric is typically performed while the fibers are in a relaxed state (e.g., little or no tension in the machine direction or the cross direction relative to the force generated by the shrinking fibers). In another embodiment, the shrinkage can be controlled in the machine direction and/or the cross direction using controlled dimensional change processes such as, but not limited to, tenter frame processes, sanforizing processes, creping processes, allied processes, and combinations thereof. The activation conditions, the fiber types, the number of nonwoven layers in the nonwoven fabric, and the like, are selected to produce desired effects (e.g., bulk, textural feel, and combinations thereof). The shrinkage can also be controlled in the machine direction and/or the cross direction by controlling the_ ratio of the number of fibers oriented in the machine direction to the number of fibers oriented in the cross direction.
In general, the activation temperature (e.g., of the oven or other heat source) of the second fiber is below the melting point of the polymer. Therefore, the activation conditions are dependent, at least in part, upon the type of polymeric fibers used as the second fiber. For example, the activation temperature when the second fiber is polypropylene is about 125 C to 150 C for a time of about 10 seconds to 1 minute. The activation temperature can be achieved by processes such as, but not limited to, heated gas, infrared heating sources, ovens, and the like. One skilled in the art can modify one or both of the temperature and time conditions to achieve the desired results.
In another embodiment, the nonwoven fabric includes a pattern of differentiated domains of shrinkage. The differentiated domains of shrinkage are ~e~~I~neWO 2007/041620 at#ern (described below) of first domains and G~ domains. The first domain of shrinkage is defined as the area of the nonwoven fabric that is bonded (e.g., a portion of the first fibers and the second fibers are bonded to one another), while the second domain of shrinkage is defined as the area of the nonwoven fabric that is not bonded. The shrinkage of the first domain under activation conditions is very small relative to the shrinkage of the second domain under activation conditions.
The first fibers and the second fibers are included in both the first domains and the second domains and portions of fibers may be in both domains. As mentioned above, the first fiber and the second fiber have different rates of shrinkage under certain conditions (e.g., activation temperature and time to shrink the fibers). Exposing the nonwoven fabric to activation conditions causes the second fibers to shrink in length. As the second fibers shrink, the second fibers pull the first fibers along with them. The shrinkage of the second fibers causes the first fibers to gather in regions of the second domain, which can increase bulk of the nonwoven fabric. The increase in bulk is enhanced when the nonwoven fabric is pattern bonded so that the bonded regions prevent disentanglement of the first fibers and the second fibers.
In an exemplary embodiment, a nonwoven fabric includes a single nonwoven layer including a mixture of first and second fibers. The nonwoven fabric has a pattern of differentiated domains of shrinkage cause by bonding first domains of the nonwoven fabric (first bonding domain), and leaving other portions unbonded (second bonding domain). In an embodiment, the first fiber is a non-shrinking fiber (defined below) and the second fiber is a shrinking fiber. The non-shrinking fiber and the shrinking fiber have different rates of shrinkage under certain activation conditions. The nonwoven fabric is exposed to activation conditions that cause the shrinking fiber to shrink, while the non-shrinking fiber does not substantially shrink (as described below). The shrinking fiber causes the non-shrinking fibers to gather in the second domains and increase bulk of the nonwoven fabric.
In another exemplary embodiment, a nonwoven fabric includes a first nonwoven layer including a first fiber, a second nonwoven layer including a second fiber, and a third nonwoven layer including the first fiber. The nonwoven fabric has a pattern of differentiated domains of shrinkage caused by bonding first domains of the ,,noawouo,n,fabr.ic.,:(ehq~,Qn dog the first, the second, and the third nonwoven layers), and leaving other portions unbonded (second bonding domain). In an embodiment, the first fiber is a non-shrinking fiber (defined below) and the second fiber is a shrinking fiber. The non-shrinking fiber and the shrinking fiber have different degrees of shrinkage under certain activation conditions. The nonwoven fabric is exposed to activation conditions that cause the shrinking fiber to shrink, while the non-shrinking fiber does not substantially shrink (as described below). The shrinking fiber in the second nonwoven layer causes the non-shrinking fibers in the first and third nonwoven layers to gather in the second domains and increase bulk of the nonwoven fabric.

Nonwoven Fabric As mentioned above, the nonwoven fabric includes, but is not limited to, at least a first fiber and a second fiber. In an embodiment, the nonwoven fabric includes a first fiber, a second fiber, and a third fiber. Other embodiments may include four or more fibers (e.g., a first fiber, a second fiber, ... and a"nt"" fiber).
Details about the fibers are described herein.
The nonwoven fabric can include one or more nonwoven layers (e.g., a first nonwoven layer, a second nonwoven layer, ... and a"nt"" nonwoven layer).
Embodiments of the present disclosure can include nonwoven fabrics having 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or more, nonwoven layers. Each nonwoven layer can include, but is not limited to, a first.fiber and/or a second fiber as well as additional fibers. In an embodiment, the nonwoven layers alternate between a nonwoven layer including a first fiber and a nonwoven layer including a second fiber. In an embodiment, the nonwoven layers alternate between a nonwoven layer including a non-shrinkable fiber and a nonwoven layer including a shrinkable fiber. Representative embodiments of nonwoven fabrics are described herein, while other embodiments having at least the first fiber and the second fiber that have different levels or rates of shrinkage are also included within the scope of the present disclosure.
In one embodiment, the nonwoven fabric includes one nonwoven layer. The nonwoven layer includes at least the first fiber and the second fiber. In another embodiment, the nonwoven layer includes the first fiber, the second fiber, and one or more additional fibers.

in an emaodiment, the nonwoven fabric includes a first nonwoven layer and a ... .,,~.. .,.,,., ...,;. .. .m... ...,.,. r.
second nonwoven layer. The first nonwoven layer is disposed on the second nonwoven layer. In one embodiment, the first nonwoven layer is made of the first fiber and the second nonwoven layer is made of the second fiber. In another embodiment, the first nonwoven layer is made of the first fiber and the second fiber and the second nonwoven layer is made of the first fiber, the second fiber, a third fiber, or any combination thereof.
In an embodiment, the nonwoven fabric includes a first nonwoven layer, a second nonwoven layer, and a third nonwoven layer. In one embodiment, the first nonwoven layer and the third nonwoven layer are made of the first fiber, while the second nonwoven layer is made of the second fiber. In another embodiment, the first nonwoven layer is made of a first fiber, the second nonwoven layer is made of a second fiber, and the third nonwoven layer is made of a third fiber. In another embodiment, any of the nonwoven layers described in the previous embodiments can include combinations of the first fiber, the second fiber, the third fiber, and/or one or more other fibers.
In each of the embodiments of the nonwoven fabrics, the types of fibers and the combination of fibers (e.g., in the same or different layers) can be selected according to the particular characteristics (e.g., bulk of the nonwoven fabric, texture of one or more surfaces of the nonwoven fabric, and the like) desired for a particular nonwoven fabric. It should be noted that conditions under which the nonwoven fabric is bonded and activated as well as the pattern of differentiated domains of shrinkage could be used to tailor the characteristics of the nonwoven fabric.
The nonwoven fabrics can be formed using one or more processes. The nonwoven fabrics can be formed using processes such as, but not limited to, carded thermal bond, carded spun lace, carded through-air bond, wet laying, carded needlepunch, spun bond, air laying, melt blowing, and combinations thereof, each of which have the meaning typically attributed to them in the art. In an embodiment, the nonwoven fabrics are formed using carded thermal bond processes.
Additional details regarding embodiments of the nonwoven fabric are described in the examples.
As mentioned above, the nonwoven fabrics have a pattern of differentiated domains of shrinkage. The patterns of differentiated domains of shrinkage can be õmade, wsinn,.,mow~,,,~~~~~r~~,,(e.g., which can be provided by any nonwoven roll maunfacturer, such as Andritz Kusters GmbH & Co. KG (Germany), and the like) or by using other patterns as well. The patterns can be made using processes such as, calendar bonding with patterned rolls, patterning jets in hydroentangling, patterned needlepunching, and the like, and combinations thereof.
After the fibers of the nonwoven fabric have been subject to activation conditions to form the bulk, the nonwoven fabric can be post treated. The post treatments include, but are not limited to, corona, plasma, soil release, flame retardant, anti-microbial, softener, and the like, and combinations thereof.
Fibers The first fiber can include, but is not limited to, natural fibers or naturally derived fibers (hereinafter referred to as "natural fiber"), thermoplastic polymer fibers, and thermoset and high performance polymer fibers. The second fiber can include, but is not limited to, polymeric fibers (e.g., thermoplastic polymer fibers).
Additional fibers (e.g., the third fiber and so on) can include, but are not limited to, natural fibers, polymeric fibers, and thermoset and high performance fibers. The first fiber and the second fiber can include, but are not limited to, polymer blend fibers, bi-component fibers (e.g., a fiber comprising of two different polymers of differing chemical constitution/properties), and bi-constituent fibers (e.g., fiber composed of two or more dissimilar fibers combined before the extrusion process). The first fiber and the second fiber can be made by the same process or by a different process.
The natural fibers can include, but are not limited to, plant fibers, vegetable fibers, and animal/insect fibers. The natural fibers are derived from fibers of animal coats and silkworm cocoons, and fiber of plants seeds, leaves, stems, and the like.
Exemplar natural fibers include, but are not limited to, wool, cotton, silk, linen, ramie, hemp, and jute. In an embodiment, the natural fiber includes, but is not limited to, rayon, Lyoceli, polylactic acid, soybean protein,and combinations thereof.
The thermoset and high performance polymers can include, but are not limited to, carbon fibers, glass fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, polyaramid fibers, combinations thereof, and the like.
The polymeric fibers and thermoplastic polymer fibers can be made of copolymers, terpolymers, and higher polymers. It should be noted that the term WO 2007/041620 Te '''1 +'f r PCT/US2006/038747 õcq,po,l~rmpr,'p in,cludes two o more monomers in the same polymer chain. I ne polymeric fibers and thermoplastic polymer fibers can be mono-component or multi-component. The polymer fibers and thermoplastic polymer fibers can be polymer blends.
The polymeric fibers and thermoplastic polymer fibers can include thermoplastic polymers such as, but not limited to, polymer blends or copolymers of each of the following: polyolefins, polyesters, polypropylene, polyethylene, polybutene, polymethylpentene, ethylene-propylene, polyamides, polyurethanes, polyvinyl acetates, ethylene vinyl acetates, polyetheresters, polyetherurethane, polyvinyl acetates, and combinations thereof.
In an embodiment, the polymeric fibers and thermoplastic polymer fibers can be made of materials such as, but not limited to, polymer blends or copolymers of each of the following: polyolefins, polyesters, polyamides, polyvinyl acetates, polyacrylonitriles, polyvinyl alcohol and ethylene acrylic acid, combinations thereof.
In an embodiment, the polymeric fibers and thermoplastic polymer fibers can include spinnable polymeric materials such as polyolefins and blends comprising 'polyolefins (e.g., See U.S. Pat. Nos. 5,733,646, 5,888,438, 5,431,994, 5,318,735, 5,281,378, 5,882,562 and 5,985,193, the disclosures of which are incorporated by reference herein in their entireties).
In an embodiment, the polymer is a polypropylene or a blend including a polypropylene. The polypropylene can include polypropylenes that are spinnable.
The polypropylene can be atactic, heterotactic, syndiotactic, isotactic and stereoblock polypropylene--including partially and fully isotactic, or at least substantially fully isotactic--polypropylenes.
The terms polymers (e.g., polyolefins, polypropylene, polyethylene, and the like) include homopolymers and heteropolymers (e.g., copolymers and terpolymers), and mixtures thereof (including blends and alloys produced by mixing separate batches or forming a blend in situ). For example, the polymer can include copolymers of olefins, such as propylene, and these copolymers can contain various components.
As used herein, polypropylene is utilized in its ordinary commercial meaning wherein the polypropylene is a substantially linear molecule. Further, as used herein, a polypropylene composition includes a material that contains a broad ht;d,i~~r.jho~l~)qt~;,,of linear polypropylene to enable the obtaining ot tiaers and filaments that have superior spinning and thermal bonding characteristics.
Conventional polymeric fibers include polypropylene staple fibers. These fibers may also include bicomponent fibers containing various combinations of polypropylene or a combination of other polymeric materials such as polyethylene. A
polymeric fiber of particular interest conventionally used in producing nonwoven webs or fabrics is a high thermal bond strength spun melt fiber described in US
Patent No. 5,281,378, incorporated herein by reference in its entirety.
In an embodiment, the polypropylene can have an average molecular weight from about 3x105 to about 5x105, a spun melt flow rate, MFR (determined according to ASTM D-1238-86 (condition L; 230/2.16), which is incorporated by reference herein in its entirety) of about 7 to about 50 dg/min, and/or a spin temperature within the range of about 220 to 315 C, about 240 to 300 C, and about 255-285 C.
In an embodiment, the polypropylene can be linear or branched, such as disclosed by U.S. Pat. No. 4,626,467, which is incorporated by reference herein in its entirety, and is preferably linear. In addition, the polypropylene to be made into fibers can include polypropylene compositions as taught in U.S. Pat. Nos.
5,629,080, 5,733,646 and 5,888,438 and European Patent Application No. 0 552 013, which are incorporated by reference herein in their entireties. Furthermore, polymer blends such as disclosed in U.S. Pat. No. 5,882,562, and European Patent Application No.
0 719 879, which are incorporated by reference herein in their entireties, can also be utilized.
The first and the second fiber can have the same or a different size and/or cross-section. The first fiber and the second fiber can have a denier of about 0.1 to 50 denier per filament. The first fiber and the second fiber can be continuous or staple, with a length of about 1 mm to 250 mm.
The melt flow rate, MFR, is dependent upon the type of polymer the fiber is made of, and, thus, the MFR can vary depending on which fibers are selected for each particular application. In an embodiment, the first polyolefin fiber and the second polyolefin fiber can have a melt flow rate (determined according to ASTM D-1238-86 (condition L; 230/2.16), which is incorporated by reference herein in its entirety) of about 10 to 400 dg/min, but the MFR depends on the chemical composition of the fibers.

an embodimept,thg first fiber has a first fiber shrinkage percentage (measured using TMA) and the second fiber has a second fiber shrinkage percentage, where the difference in the first fiber shrinkage percentage and the second fiber shrinkage percentage is at least about 8%, is at least about 9%, is at least about 10%, is at least about 12%, or is at least about 15%. It should be noted that in an embodiment the first fiber might not shrink and increase in length.
In an embodiment, the first fiber has a first fiber shrinkage of less than about 10%, less than about 8%, less than about 6%, less than about 3%, or less than about 1%, where each is measured at the same conditions (e.g., a temperature near the activation temperature of the fiber of interest), and may be referred to as the "non-shrinking fiber".
The non-shrinking fiber can include, but is not limited to, polypropylene, polyester, and combinations thereof. In an embodiment where the non-shrinking fiber is made of polypropylene, the fiber shrinkage is less than about 10 % at about 140 C. It should be noted that in an embodiment the non-shrinking fiber might not shrink and increase in length.
The second fiber has a fiber shrinkage of greater than about 9%, greater than about 10%, greater than about 11 %, greater than about 12%, greater than about 13%, and may be referred to as the "shrinking fiber".
The shrinking fiber can include, but is not limited to, polypropylene, polyester, polyethylene, and bicomponent fibers made therefrom. In an embodiment where the shrinking fiber is made of polypropylene, the fiber shrinkage is about 9 to 40 % at 140 C.
The production of polymeric fibers for nonwoven materials can include the use of a mix of at least one polymer with nominal amounts of additives, such as, but not limited to, antioxidants, stabilizers, pigments, antacids, process aids and the like.
Thus, the polymer or polymer blend can include various additives, such as, but not limited to, melt stabilizers, antioxidants, pigments, antacids, antistatic aids, emulsifiers, preservatives, and process aids. The types, identities, and amounts of additives can be determined by those of ordinary skill in the art upon consideration of requirements of the product.
Various finishes can be applied to the fibers to maintain or render them hydrophilic or hydrophobic. Finish compositions including hydrophilic finishes or hy,d.r,op~q.hi.c,,fj,nish,esõMgayelected by those of ordinary skill in the art according to the characteristics of the apparatus and the needs of the product being manufactured.
Also, one or more components can be included in the polymer blend for modifying the surface properties of the fiber, such as to provide the fiber with repeat wettability, or to prevent or reduce build-up of static electricity.
Hydrophobic finish compositions preferably include antistatic agents. Hydrophilic finishes may also include such agents.
Additional details regarding embodiments of the nonwoven fabric are described in the examples.

Examples Now having described the embodiments of the present disclosure, in general, the Examples describe some additional embodiments of the present disclosure.
While embodiments of present disclosure are described in connection with the Examples and the corresponding text and figures, there is no intent to iimit embodiments of the present disclosure to these descriptions. On the contrary, the intent is to cover all alternatives, modifications, and equivalents included within the spirit and scope of embodiments of the present disclosure.
Table 1, as shown in FIG. 3, illustrates some exemplar embodiments of nonwoven fabrics A-G with combinations of fibers NS1, NS2, NS3, NS4, NS5, S1, and S2. The examples provide a number of embodiments ranging in fabric weight, construction, fiber composition, fiber type, the number of nonwoven layers, method of fabric formation, and the like.
FIGS. 2A and 2B illustrate photomicrographs of cross sectional views of nonwoven fabric of A in Table 1. FIG. 2A illustrates an embodiment of a nonwoven fabric used for producing the bulky nonwoven fabric that has not been activated by a thermal bulking step. FIG. 2B illustrates the nonwoven web that has been activated to produce the bulky nonwoven web It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations, and are set forth only for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described embodiments of th,e,rc~isc~g~,~re vyithqut depart,ing substantially from the spirit and principies oT tne disclosure. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.

Claims

1. A fabric comprising:
a nonwoven fabric having at least a first fiber and a second fiber, wherein the first fiber has a first fiber shrinkage percent and the second fiber has a second fiber shrinkage percent, wherein the difference in the first fiber shrinkage percent and the second fiber shrinkage percent is at least about 8%.

2. The fabric of claim 1, wherein the nonwoven fabric includes at least a first domain of shrinkage and a second domain of shrinkage, wherein the first domain and the second domain define differentiated domains of shrinkage.

3. The fabric of claim 1, wherein the difference in the first fiber shrinkage percent and the second fiber shrinkage percent is at least about 10%.

4. The fabric of claim 1, wherein first fiber is a non-shrinking fiber, wherein the non-shrinking fiber has a first fiber shrinkage percent of less than about 5 %.

5. The fabric of claim 1, wherein first fiber is a non-shrinking fiber, wherein the non-shrinking fiber has a first fiber shrinkage percent of less than about 3 %.

6. The fabric of claim 1, wherein the first fiber is a thermoplastic polymeric fiber made of a polymer selected from: polymer blends or copolymers of each of the following: polyolefins, polyesters, polypropylene, polyethylene, polybutene, polymethylpentene, ethylene-propylene, polyamides, polyurethanes, polyvinyl acetates, ethylene vinyl acetates, polyetheresters, polyetherurethane, polyvinyl acetates, and combinations thereof; wherein the second fiber is a thermoplastic fiber selected from: polymer blends, or copolymers, of each of the following: polyolefins, polyesters, polypropylene, polyethylene, polybutene, polymethylpentene, ethylene-propylene, polyamides, polyurethanes, polyvinyl acetates, ethylene vinyl acetates, polyetheresters, polyetherurethane, polyvinyl acetates, and combinations thereof.

7. The fabric of claim 1, wherein the first fiber is a natural fiber made of a material selected from: wool, cotton, silk, linen, ramie, hemp, jute, and combinations thereof; wherein the second fiber is a polymeric fiber selected from: polymer blends or copolymers of each of the following: polyolefins, polyesters, polypropylene, polyethylene, polybutene, polymethylpentene, ethylene-propylene, polyamides, polyurethanes, polyvinyl acetates, ethylene vinyl acetates, polyetheresters, polyetherurethane, polyvinyl acetates, and combinations thereof.

8. The fabric of claim 1, wherein the first fiber is a fiber derived from natural material selected from: rayon, Lyocell, polylactic acid, soybean protein, and combinations thereof; wherein the second fiber is a polymeric fiber selected from: polymer blends and copolymers of each of the following: polyolefins, polyesters, polypropylene, polyethylene, polybutene, polymethylpentene, ethylene-propylene, polyamides, polyurethanes, polyvinyl acetates, ethylene vinyl acetates, polyetheresters, polyetherurethane, polyvinyl acetates, and combinations thereof.

9. The fabric of claim 1, wherein the first fiber is a fiber selected from:
carbon fibers, glass fibers, polyacrylonitrile fibers, polyvinyl alcohol fibers, polyaramid fibers, combinations thereof; wherein the second fiber is a polymeric fiber selected from: polymer blends and copolymers of each of the following:
polyolefins, polyesters, polypropylene, polyethylene, polybutene, polymethylpentene, ethylene-propylene, polyamides, polyurethanes, polyvinyl acetates, ethylene vinyl acetates, polyetheresters, polyetherurethane, polyvinyl acetates, and combinations thereof.

10. The fabric of claim 1, wherein the nonwoven fabric includes at least a first nonwoven layer, wherein the first fiber and the second fiber are included in the first nonwoven layer.

11. The fabric of claim 1, wherein the nonwoven fabric includes a third fiber having a third fiber shrinkage percent, wherein the difference in the third fiber shrinkage percent and the second fiber shrinkage percent is at least about 8%, wherein the nonwoven fabric includes at least a first nonwoven layer, wherein the first fiber, the second fiber, and the third fiber are included in the first nonwoven layer.

12. The fabric of claim 1, wherein the nonwoven fabric includes at least two nonwoven layers, wherein a first nonwoven layer is disposed on a second nonwoven layer, and wherein the first fiber is in the first nonwoven layer and the second fiber is in the second nonwoven layer.

13. The fabric of claim 1, wherein the nonwoven fabric includes at least three nonwoven layers, wherein a first nonwoven layer is disposed on a second nonwoven layer, wherein a third nonwoven layer is disposed on the second nonwoven layer on the side opposite the first nonwoven layer, wherein the first fiber is in the first nonwoven layer and the third nonwoven layer, and wherein the second fiber is in the second nonwoven layer.

14. The fabric of claim 1, wherein the first fiber and the second fiber are each selected from: polymer blend fibers, bi-component fibers, bi-constituent fibers, and combinations thereof.

15. An article, comprising:
a nonwoven fabric having at least a first fiber and a second fiber, wherein the first fiber has a first fiber shrinkage percent and the second fiber has a second fiber shrinkage percent, wherein the difference in the first fiber shrinkage percent and the second fiber shrinkage percent is at least about 8%, and wherein the article is selected from a cleaning wipe, a diaper, a textile stretch component, an incontinence care product, a feminine care product, felts, and a filter.

16. A fabric comprising:
a nonwoven fabric having at least a first domain of shrinkage and a second domain of shrinkage, wherein the first domain and the second domain define differentiated domains of shrinkage, and wherein the nonwoven fabric includes at least a first fiber and a first shrinking fiber.

17. The fabric of claim 16, wherein the first fiber is a first polypropylene fiber and wherein the first shrinking fiber is a second polypropylene fiber, wherein the first polypropylene fiber and the second polypropylene fiber have a difference in shrinkage percentage of at least about 8%.

18. A method of forming a nonwoven fabric, comprising:
providing a nonwoven fabric including a first fiber and a second fiber, wherein the first fiber has a first fiber shrinkage percent and the second fiber has a second fiber shrinkage percent, wherein the difference in the first fiber shrinkage percent and the second fiber shrinkage percent is at least about 8%;
forming at least a first domain of shrinkage and a second domain of shrinkage, wherein the first domain and the second domain define differentiated domains of shrinkage, wherein a portion of the first fiber and a portion of the second fiber in the first domain are bonded; and heating the nonwoven fabric to an activation temperature of the second fiber, wherein the second fiber shrinks and causes the first fiber to gather to increase the thickness of the nonwoven fabric in the second domain.

19. A method of forming a nonwoven fabric, comprising:
providing a nonwoven fabric including a first fiber and a second fiber, wherein the first fiber has a first fiber shrinkage percent and the second fiber has a second fiber shrinkage percent, wherein the difference in the first fiber shrinkage percent and the second fiber shrinkage percent is at least about 8%; and

20 heating the nonwoven fabric to an activation temperature of the second fiber, wherein the second fiber shrinks and causes the first fiber to gather to increase the thickness of the nonwoven fabric.

21