Nonwoven wiping fabrics having variable surface topography

Abstract

The invention provides for a nonwoven fabric wipe having a variance in surface topography. The variance in surface topography is provided by two or more projections of differing height extending from the surface of the fabric or two or more projections in stacked formation. The projections may be disposed on the surface of the wipe in a patterned, array-like arrangement or the projections may be randomly disposed on the surface. The variance in projection height will typically provide for the projections to perform differing cleaning functions based upon the height, geometry, size and distribution of the projections.

Description

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of priority Provisional Application No. 60/611,957, filed Sep. 22, 2004, the disclosures of which are incorporated herein by reference.

TECHNICAL FIELD

The present invention relates generally to nonwoven fabrics, and more particularly, to a nonwoven fabric exhibiting improved particulate entrapment characteristics attributed to the fabric's distinctive surface topography.

BACKGROUND OF THE INVENTION

Nonwoven fabrics are suitable for use in a wide variety of applications where the efficiency with which the fabrics can be manufactured provides a significant economic advantage for these fabrics versus traditional textiles. Over the years, the use of nonwoven disposable substrates in cleaning applications has been well practiced. Further, such substrates have been impregnated with cleaning agents such as astringents, solvents, detergents and other chaotropes. The resulting cleaning products fabricated from such impregnated substrates have found acceptance with the general public as a convenient and practical means for the cleaning of surfaces. In particular, such constructs have been widely successful in the home care and hygiene markets.

More recently, hydroentanglement techniques have been utilized to further enhance the disposable nonwoven cleaning substrates by imparting surface projections into the fabric that extend out from the face of the fabric in the z-direction. The fabric is affected by hydraulic jets as it is advanced over a forming surface, such as embossed belt, metal drums, and three-dimensional image transfer devices. Such three-dimensional image transfer devices are disclosed in U.S. Pat. No. 5,098,764, entitled “Non-woven Fabric and Method and Apparatus for Making the Same” issued on Mar. 24, 1992, in the name of inventors Bassett et al. The use of such image transfer devices is desirable for providing a fabric with enhanced physical properties as well as an aesthetically pleasing appearance.

For specific cleaning applications, it is desirable to have a wipe that is capable up picking up various particulates, including dirt, food crumbs, hair, grass, dust, as well as cellular debris. Heretofore, suitable nonwoven fabrics included those imparted with three-dimensional images, as disclosed in the commonly assigned U.S. Pat. Nos. 6,735,833, entitled “Nonwoven Fabrics Having a Durable Three-dimensional Image”, issued on May 18, 2004, in the name of inventors Putnam et al. and U.S. Pat. No. 6,725,512, entitled “Imaged Nonwoven Fabric for Cleaning Applications”, issued on Apr. 27, 2004, in the name of inventor Carter, hereby incorporated by reference. The imparted images on these fabrics exhibit a uniform repeating pattern of the same image height. The image height is defined herein as the distance the image extends from the face of the fabric in the z-direction.

Notwithstanding various attempts in the prior art to develop a nonwoven fabric having a plurality of surface projections acceptable for home, medical and hygiene wiping applications, a need continues to exist for a nonwoven fabric which provides an improved cleaning performance, particulate capturing performance, and exhibits better holding capacity, thus, decreasing the need for repeat wiping.

SUMMARY OF THE INVENTION

The present invention is directed to a nonwoven fabric and associated methods of manufacturing the nonwoven fabric. The nonwoven fabric exhibits improved particulate entrapment characteristics attributed to the fabric's distinctive surface topography. The distinctive surface topography is defined by at least a plurality of first and second surface projections that extend from the face of the fabric. The plurality of first surface projection extends a first distance from the face of the fabric to perform a first cleaning function and the plurality of second surface projection extends a second distance from the face of the fabric to perform a second cleaning function. The dual cleaning function of the fabric is thus conducive to a wide variety of cleaning applications.

In accordance with the present invention, the nonwoven fabric is suitable for hard surface cleaning applications, such as floor wipes, dusting wipes, dish washing wipes, etc., as well as hygienic skin cleansing wipes, such as baby wipes and facial wipes. The cleaning surface of the wipes includes an irregular topography that optimizes the amount of useable surface area in the wipe. In one embodiment, a first surface projection of a first height performs a first function, such as dust collecting and a second surface projection of a second height performs a second function, such a food particulate capture. The first and second surface projections may be stacked, for example, the second surface projection is an extension of the first surface projection. Further, the first and second surface projection may be positioned side-by-side.

In another embodiment, a plurality of imparted surface projections of varying heights may collectively form numerous valleys or other formations within the surface of the wipe to increase the overall particulate holding capacity of the wipe.

The geometry of the projections, the cross-sectional area of the projections, the distribution of the projections on the wipe, the height variance of the projections are all factors that effect the cleaning performance of the wipe and/or the particulate holding capability of the wipe.

For wipe applications that are required to withstand additional sheers forces exerted by a cleaning process, such as dish washing wipes, a reinforcement fabric may be incorporated into the nonwoven fabric. Reinforcement fabrics, also referred to as a “scrim” material, are described in detail in U.S. Pat. No. 4,636,419, entitled “Net And Method Of Producing Same”, issued on Jan. 13, 1987 in the name of inventor Madsen et al. A preferred reinforcement fabric is a spunbond material, which includes continuous filaments typically formed by extrusion of thermoplastic resins through a spinneret assembly, creating a plurality of continuous thermoplastic filaments.

Subsequent to fabric formation, the nonwoven cleaning article may be treated with a performance or aesthetic modifying composition, such as an aqueous or powder cleanser, emollient, latherant, fragrance, pigment, insect repellent or the like, to further alter the wiping fabric to meet end-use article requirements. A polymeric binder composition can be selected to enhance durability characteristics of the cleaning article, while maintaining the desired softness and drapeability of the wiping fabric. Further, a surfactant can be applied so as to impart hydrophilic properties. Further still, an electrostatic modifying compound can be used to aid in cleaning or dusting applications. Other features and advantages of the present invention will become readily apparent from the following detailed description, the accompanying drawings, and the appended claims.

The performance or aesthetic modifying additive may be limited to the first projections, the second projection or both. Additionally, the invention provides for one additive to be applied to the first projections and for a second additive to be applied to the second projections.

As such, the present invention provides for a wiping product that has multiple or varying surface topography. Such variance in surface topography allows for the fabric to provide for dual wiping capabilities. Dual wiping capabilities provide improved cleaning performance, particulate capturing performance, and exhibits better holding capacity, thus, decreasing the need for repeat wiping or wiping with another single-purpose wipe.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagrammatic top-view of a nonwoven wiping fabric having variable surface topography, in accordance with an embodiment of the present invention;

FIG. 2 is a diagrammatic top-view of a nonwoven wiping fabric having variable surface topography, in accordance with an embodiment of the present invention;

FIG. 3 is a side view of a nonwoven wiping fabric having variable surface topography, in accordance with an embodiment of the present invention;

FIG. 4 is a side view of a nonwoven wiping fabric having variable surface topography, in accordance with an embodiment of the present invention;

FIG. 5 is a side view of a nonwoven wiping fabric having variable surface topography, in accordance with an embodiment of the present invention;

FIG. 6 is a photographic top-view of a nonwoven wiping fabric having variable surface topography, in accordance with an embodiment of the present invention; and

FIG. 7 is a diagrammatic view of an apparatus for manufacturing a durable nonwoven fabric, embodying the principles of the present invention.

DETAILED DESCRIPTION

The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.

The present invention is directed to an improved wiping fabric that includes at least a plurality of two surface projections that have dissimilar heights, which lend to an irregular surface topography of the nonwoven wiping fabric. Accordingly, a plurality of first surface projections extend from a face of the fabric at a first height to perform a first cleaning function, while a plurality of second surface projections extend from the face of the fabric at a second height to perform a second cleaning function.

FIG. 1 is top-view illustration of a wiping fabric having projections of differing heights, in accordance with an embodiment of the present invention. In the illustrated embodiment the surface of fabric 10 includes a series of arrays 12 with each array including a 4×4 arrangement of 16 projections 14. The inner projections in each of the arrays, otherwise referred to herein as first projections 14A, extend a first distance from the surface of the fabric and perform a first wiping function. The outer projections in each of the arrays, otherwise referred to herein as the second projections 14B, extend from a second distance, different from the first distance, from the surface of the fabric and perform a second wiping function. Typically, the first projections 14A will extend a first distance from the fabric that is less than the distance from which the second projections 14B extend from the fabric. In such an embodiment, the first projections 14A will typically be implement to wipe and entrap larger sized particulate matter, such as larger sized food pieces or the like while the second projections 14B will typically be implemented to wipe and entrap smaller sized particulate matter, such as smaller sized food pieces (i.e., crumbs) or the like. However, the opposite arrangement in which the first projections 14A extend a first distance.

It is noted that while the example of FIG. 1 shows a series of arrays with each array having a similarly patterned arrangement of an equal number of projections, other embodiments of the invention may have a series of arrays in which the pattern of arrangement of projections differs from array to array and the number of projections within an array may differ. Additionally, while FIG. 2 is illustrative of a series of arrays including a pattern of projections, other embodiments may not include arrays or a patterned arrangement of projections. Thus, the projections may be arranged on the surface of the fabric in a random distribution or a non-repeating pattern. Typically, the end-use of the wipe will dictate how the projections are arranged on the surface of the fabric.

Additionally, it is noted that while the cross-sectional geometry and cross-sectional area of each projection is shown in FIG. 1 as being generally equal (i.e., a square shaped geometry); the projections may differ from to array-to-array or from projection-to-projection in terms of cross-sectional geometry and/or cross-sectional area. For an example, see the top-view image of FIG. 6, which illustrates a nonwoven fabric having projections of differing height, in accordance with an embodiment of the present invention. The first projections 14A extend a first distance from the surface of the fabric and have differing top-view geometries, such as the illustrated circular geometry and rectangular geometry. The second projections 14B extend a second distance from the surface of the fabric and have similar top-view geometry, such as the illustrated circular geometry. In addition, the cross-sectional area of an individual second projection is greater than the cross-sectional area of any one first projection.

FIG. 3 illustrates a cross-sectional side-view of the nonwoven fabric having projections of differing heights shown in FIG. 1, in accordance with an embodiment of the present invention. As shown, the first projections 14A have a height that is less than the height of the second projections 14B. In this arrangement the first projections will typically provide for the wiping and entrapment of large sized particulates, while the second projections will typically provide for the wiping and entrapment of smaller sized particulates.

FIG. 2 is a top view representative of an alternate embodiment of the present invention, in which in which different height projections are arranged in a pattern on the surface of the nonwoven fabric 20. The first projections 22 arranged in circular patterns throughout the surface of the fabric and are defined as having a first height or distance extending from the surface of the fabric. The second projections 24 are arranged in a hexagonal pattern inside and outside of the circular patterns formed by the first projections 22 and are defined as having a second height or distance extending from the surface of the fabric, which differs from the height of the first projections 22 and the third projections 26. The third projections 26 are arranged within each of the hexagonal patterns of second projections and are defined as having a third height or distance extending from the surface of the fabric, which differs from the height of the first projections 22 and the second projections 24. As such the first, second and third projections having differing heights will be suited to perform differing wiping and/or entrapment capabilities. The wiping and/or entrapment capabilities will typically vary based upon the frequency of the projections, the size of the projections, the geometry of the projections, the height of the projections and the variance in height of the projections.

FIG. 4 illustrates a cross-sectional side-view of the nonwoven fabric having projections of varying heights shown in FIG. 2, in accordance with an embodiment of the present invention. As shown, the first projections 22 have a height that is greater than the height of the second projections 24 and third projections 26. In this arrangement the first projections will typically provide for the wiping and entrapment of small sized particulates, while the second and third projections will typically provide for the wiping and entrapment of larger sized particulates.

FIG. 5 provides for a side view illustration of a nonwoven fabric wipe having a stacked arrangement of surface projections, in accordance with an embodiment of the present invention. The fabric 30 includes first projections 32 that extend a first distance from the surface 34 of the fabric. Additionally, the fabric includes second projections 36 that extend a second distance from the surface 34 of the fabric. One or more third projections 38 extend from the distal portion 40 of the second projections 36. As such, the first and third projections 32 and 38 having differing extended heights from the surface 34 of the wipe will typically perform differing wiping and/or entrapment capabilities. The wiping and/or entrapment capabilities will typically vary based upon the frequency of the projections, the size of the projections, the geometry of the projections, the height of the projections and the variance in height of the projections. In the illustrated embodiment of FIG. 5, the first projections will typically provide for the wiping and/or entrapment of larger sized particulates, while the third projections that extend from the second projections will typically provide for the wiping and/or entrapment of smaller sized particulates.

The wiping fabric embodying the principles of the present invention is especially suitable for various home care applications, wherein the end use article may be a dry or wet hand held wipe, utilized in a mitt formation or in combination with a cleaning implement capable of retaining the cleaning article. The various end uses suitable for cleaning household surfaces such as, floors, kitchen and bathroom countertops, sinks, bathtubs, showers, appliances, fixtures, and the like.

The wiping fabric embodying the principles of the present invention is also suitable for personal cleansing articles. Examples of such applications include dry or wet facial wipes, body wipes, baby wipes and the like. Various aqueous and non-aqueous additive compositions may be used to treat the wiping fabric of the present invention depending on the desired end use. Suitable methods known in the art for applying the additive compositions include, but are not limited to flood coating, spray coating, padding, kiss coating, and metered dosing. The additives may be applied to the fabric in its entirety or, alternatively, additives may be limited to application of the first and/or second projections. As such the first projections may be treated with a first performance enhancing additive and the second projections may be treated with a second performance enhancing additive.

In addition to home care and personal care end uses, the nonwoven wiping fabric of the present invention may be used in industrial and medical applications. For instance, in the industrial realm the wipe may be useful in indoor and outdoor painting and cleaning outdoor surfaces, such as lawn furniture, grills, and outdoor equipment that would benefit from desirable low linting attributes of the laminate. The industrial application wipe of the present invention may also benefit from having aqueous or non-aqueous solvent additives. Aqueous or non-aqueous functional industrial solvents include, oils, such as plant oils, animal oils, terpenoids, silicon oils, mineral oils, white mineral oils, paraffinic solvents, polybutylenes, polyisobutylenes, polyalphaolefins, and mixtures thereof, toluenes, sequestering agents, corrosion inhibitors, abrasives, petroleum distillates, combinations thereof and the like.

A medical wiping fabric may incorporate an antimicrobial composition, including, but not limited to iodines, alcohols, such as such as ethanol or propanol, biocides, abrasives, metallic materials, such as metal oxide, metal salt, metal complex, metal alloy or mixtures thereof, bacteriostatic complexes, bactericidal complexs, combinations thereof and the like.

The wiping fabric of the present invention is particularly suitable for dispensing from a tub of stacked, folded wipes, or for dispensing as “pop-up” wipes, in which the wipes are stored in the tub as a perforated continuous roll, wherein upon pulling a wipe out of the tub, an edge of the next wipe is presented for easy dispensing. The wipes of the present invention can be folded in any of various known folding patterns, such as C-folding, Z-folding and the like. A Z-folded configuration enables a folded stack of wipes to be interleaved with overlapping portions. The wipes may be packaged in various convenient forms, whereby the method of packaging is not meant to be a limitation of the present invention.

With reference to FIG. 7, shown is a schematic representation of an apparatus for making the nonwoven fabric of the present method, in accordance with another embodiment of the present invention. The nonwoven fabric is typically formed from a fibrous matrix, which typically includes staple length fibers, but may include substantially continuous filaments. The fibrous matrix is preferably carded and cross-lapped to form a fibrous batt. In a current embodiment, the fibrous batt comprises 100% cross-lap fibers, that is, all of the fibers of the web have been formed by cross-lapping a carded web so that the fibers are oriented at an angle relative to the machine direction of the resultant web. U.S. Pat. No. 5,475,903, entitled “Composite Nonwoven Fabric And Method”, issued on Dec. 19, 1995, in the name of inventor Collins, which is hereby incorporated by reference as if set forth fully herein, illustrates a web drafting apparatus.

Optionally, s support layer or scrim may be placed in face to face juxtaposition with the fibrous web and hydroentangled to form precursor web P. Alternately, the fibrous web can be hydroentangled first to form precursor web P, and subsequently, at least one support layer or scrim may be applied to the precursor web, and the composite construct optionally further entangled with hydraulic jet manifolds, then imparted two or more surface projections by way of entanglement on a foraminous surface, preferably a three-dimensional image transfer device. The present invention contemplates that the support layer or scrim be any such suitable material, including, but not limited to, wovens, knits, open mesh scrims, and/or nonwoven fabrics, which exhibit low elongation performance.

FIG. 7 illustrates a schematic drawing of a hydroentangling apparatus for forming nonwoven fabrics in accordance with the present invention. The apparatus includes a foraminous-forming surface in the form of belt 100 upon which the precursor web P is positioned for pre-entangling by entangling manifold 110. Pre-entangling of the precursor web, prior to three-dimensional imaging, is subsequently effected by movement of the web P sequentially over a drum 120 having a foraminous-forming surface, with entangling manifold 130 effecting entanglement of the web. Further entanglement of the web is effected on the foraminous forming surface of a drum 140 by entanglement manifold 150, with the web subsequently passed over successive foraminous drums 160, for successive entangling treatment by entangling manifolds 170, 170′.

The entangling apparatus of FIG. 7 further includes a three-dimensional imaging drum 180 including a three-dimensional image transfer device for effecting imaging of the now-entangled precursor web. The image transfer device includes a moveable imaging surface which moves relative to a plurality of entangling manifolds 190 which act in cooperation with three-dimensional elements defined by the imaging surface of the image transfer device to effect imaging and patterning of the fabric being formed.

Manufacture of a nonwoven wiping fabric embodying the principles of the present invention is initiated by providing the fibrous matrix, which can include the use of staple length fibers, continuous filaments, and the blends of fibers and/or filaments having the same or different composition. Fibers and/or filaments are selected from natural or synthetic composition, of homogeneous or mixed fiber length. Suitable natural fibers include, but are not limited to, cotton, wood pulp and viscose rayon. Synthetic fibers, which may be blended in whole or part, include thermoplastic and thermoset polymers. Thermoplastic polymers suitable for blending with dispersant thermoplastic resins include polyolefins, polyamides and polyesters. The thermoplastic polymers may be further selected from homopolymers; copolymers, conjugates and other derivatives including those thermoplastic polymers having incorporated melt additives or surface-active agents. Staple lengths are selected in the range of about 0.25 inch to about 10 inches, the range of about 1.0 to about 3.0 inches being preferred and the fiber denier selected in the range of about 1.0 to about 22 denier, the range of about 1.2 to about 6 denier being preferred for general applications.

Nano-denier fibers and/or filaments may also be incorporated, either partially or fully encompassing the fiber composition of the nonwoven wiping fabric. Suitable nano-denier fibers and filaments are taught in U.S. Pat. No. 6,315,806, entitled “Method and Apparatus for Producing High Efficiency Fibrous Media Incorporating Discontinuous Sub-micron Diameter Fibers, and Web Media Formed Thereby”, issued on Nov. 13, 2001, in the name of inventor Torobin, and U.S. Pat. No. 6,269,513, entitled “Wipe Pads with Superior Solids Removal Ability Using Sub-micron Filaments”, issued on Aug. 7, 2001 in the name of inventor Torobin, both of which are hereby incorporated by reference as if set forth fully herein. The profile of the fiber and/or filament is not a limitation to the applicability of the present invention.

As such, the present invention provides for a wiping product that has multiple or varying surface topography. Such variance in surface topography allows for the fabric to provide for dual wiping capabilities. Dual wiping capabilities provide improved cleaning performance, particulate capturing performance, and exhibits better holding capacity, thus, decreasing the need for repeat wiping or wiping with another single-purpose wipe.

Many modifications and other embodiments of the invention will come to mind to one skilled in the art to which this invention pertains having the benefit of the teachings presented in the foregoing descriptions and the associated drawings. Therefore, it is to be understood that the invention is not to be limited to the specific embodiments disclosed and that modifications and other embodiments are intended to be included within the scope of the appended claims. Although specific terms are employed herein, they are used in a generic and descriptive sense only and not for purposes of limitation.

Claims

1. A nonwoven wiping fabric having a variance in surface topography, the fabric comprising:

a plurality of first surface projections extending a first height from a surface of the fabric that perform a first cleaning function; and

a plurality of second surface projections extending a second height from the surface of the fabric that perform a second cleaning function.

2. The fabric of claim 1, wherein the plurality of first surface projections and the plurality of second surface projections are disposed on the surface of the fabric in a patterned array arrangement.

3. The fabric of claim 1, wherein the plurality of first surface projections and the plurality of second surface projections are disposed on the surface of the fabric in a random arrangement.

4. The fabric of claim 1, wherein the plurality of first surface projections and the plurality of second surface projections have similar geometry.

5. The fabric of claim 1, wherein the plurality of first surface projections have a first geometry and the plurality of second surface projections have a second geometry.

6. The fabric of claim 1, wherein the plurality of first surface projections and the plurality of second surface projections have similar-surface direction cross-sectional area.

7. The fabric of claim 1, wherein the plurality of first surface projections have a first surface-direction cross-sectional area and the plurality of second surface projections have a second surface-direction cross-sectional area.

8. The fabric of claim 1, wherein the plurality of first surface projections extend a first height that is greater than the second height and perform a micro particulate cleaning function.

9. The fabric of claim 4, wherein the plurality of second surface projections extend a second height that is less than the first height and perform a macro particulate cleaning function.

10. The fabric of claim 1, further comprising a plurality of third projections extending from a distal portion of the second surface projections.

11. The fabric of claim 1, wherein the plurality of first surface projections includes a first cleaning performance additive.

12. The fabric of claim 1, wherein the plurality of second surface projections includes a second cleaning performance additive.

13. The fabric of claim 1, further comprising a support layer underlying the surface of the fabric.

14. The fabric of claim 1, further comprising staple length fibers.

15. The fabric of claim 1, further comprising continuous filaments.

16. The fabric of claim 1, wherein the plurality of first and second surface projections are imparted by hydroentangling the wiping fabric on a foraminous surface.

17. The fabric of claim 1, wherein the plurality of first and second surface projections are imparted by hydroentangling the wiping fabric on a three-dimensional image transfer device.

18. A nonwoven wiping fabric having a variance in surface topography, the fabric comprising:

a plurality of first projections extending a first height from a surface of the fabric that perform a first cleaning function; and

one or more second projections extending from a distal portion of one or more of the first projections that perform a second cleaning function.

19. The fabric of claim 18, wherein the plurality of first projections are disposed on the surface of the fabric in a patterned array arrangement.

20. The fabric of claim 18, wherein the plurality of first projections are disposed on the surface of the fabric in a random arrangement.

21. The fabric of claim 18, wherein the one or more second projections are disposed on the distal portion of the first projections in a patterned arrangement.

22. The fabric of claim 18, wherein the plurality of first projections and the one or more second projections have similar geometry.

23. The fabric of claim 18, wherein the plurality of first projections have a first geometry and the one or more second projections have a second geometry.

24. The fabric of claim 18 wherein the one or more second projections are disposed on the distal portion of the first projections in a random arrangement.

25. The fabric of claim 18, wherein the first projections perform a macro particulate cleaning function and the second projections perform a micro cleaning function.

26. The fabric of claim 18, wherein the first projections include a first cleaning performance additive.

27. The fabric of claim 18, wherein the second projections include a second cleaning performance additive.

28. The fabric of claim 18, further comprising third projections extending a second height from the surface of the fabric that perform a third cleaning function.

29. A method of making a nonwoven wiping fabric having a variance in surface topography comprising the steps of:

carding a fibrous matrix;

pre-entangling the fibrous matrix on a foraminous surface to form a fibrous batt;

advancing and hydroentangling the fibrous batt upon a three-dimensional image transfer device, wherein the three-dimensional image transfer device imparts a plurality of first surface projections extending a first height from the fibrous batt and a plurality of second surface projections extending a second height from the fibrous batt.

30. The method of claim 29, furthering comprising the step of juxtaposing a support layer in face-to-face position with the pre-entangled fibrous batt.