US20040110443A1

Movatterモバイル変換

Info

Publication number: US20040110443A1
Application number: US10/310,245
Authority: US
Inventors: Matthew Pelham
Original assignee: JENTEX Corp
Current assignee: JENTEX Corp
Priority date: 2002-12-05
Filing date: 2002-12-05
Publication date: 2004-06-10
Also published as: WO2004053219A2; WO2004053219A3; AU2003297681A1; US7253137B2; US20060258530A1; AU2003297681A8

Abstract

The present invention is directed to abrasive webs, composite materials, and methods of making abrasive webs and composite materials.

Description

FIELD OF THE INVENTION

The present invention relates to abrasive webs, composite materials, and methods of making such webs and composite materials.[0001]

BACKGROUND OF THE INVENTION

There is a need in the art for webs and composite materials having one or more of the following properties:[0002]

(1) desired abrasiveness;[0003]

(2) desired absorbency;[0004]

(3) desired bulkiness;[0005]

(4) desired softness; and[0006]

(5) desired scent or aroma.[0007]

SUMMARY OF THE INVENTION

The present invention is directed to abrasive webs and nonwoven composite materials. The abrasive webs and nonwoven composite materials may comprise one or more layers, wherein each layer provides desired properties to the web or composite material. In one exemplary embodiment of the present invention, the abrasive web comprises a first meltblown nonwoven web bonded to a second fabric, wherein the meltblown nonwoven web/fabric composite is differentially microstretched in its cross direction to produce a composite material having greater bulk, softness and drapeability relative to the pre-stretched composite material.[0008]

The present invention is further directed to methods of making abrasive webs and nonwoven composite materials having desired properties, and various uses for the abrasive webs and nonwoven composite materials.[0009]

These and other features and advantages of the present invention will become apparent after a review of the following detailed description of the disclosed embodiments and the appended claims.[0010]

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention is further described with reference to the appended figures, wherein:[0011]

FIG. 1 depicts exemplary components for abrasive webs and nonwoven composite materials of the present invention;[0012]

FIG. 2 depicts an exemplary bonded composite of the present invention;[0013]

FIG. 3 depicts an exemplary cross-sectional configuration of the bonded composite of FIG. 2 as viewed along line A-A;[0014]

FIG. 4 depicts an exemplary process for making a meltblown web for use in the abrasive webs and nonwoven composite materials of the present invention;[0015]

FIG. 5 depicts a variation of the exemplary process shown in FIG. 4, wherein a second layer is joined to the meltblown web layer;[0016]

FIG. 6 depicts another exemplary process for making abrasive webs and nonwoven composite materials of the present invention;[0017]

FIG. 7A depicts an exemplary stretching process for stretching a nonwoven composite material or one or more layers of the nonwoven composite material;[0018]

FIG. 7B depicts a cross-sectional view of the apparatus used in the stretching process of FIG. 7A; and[0019]

FIGS. 8A and 8B depict exemplary cross-sectional configurations for composite materials of the present invention.[0020]

DETAILED DESCRIPTION OF THE INVENTION

The present invention is directed to abrasive webs and nonwoven composite materials having desired properties. The abrasive webs and nonwoven composite materials possess one or more of the following properties: (1) desired abrasiveness; (2) desired absorbency; (3) desired bulkiness; (4) desired softness; (5) desired scent or aroma; and (6) the ability to be manufactured in a cost-effective manner. The present invention is also directed to methods of making abrasive webs and nonwoven composite materials and various uses for the abrasive webs and nonwoven composite materials.[0021]

The abrasive webs and nonwoven composite materials of the present invention comprise a variety of materials, which provide one or more of the above-mentioned desired properties. A description of suitable materials for forming the abrasive webs and nonwoven composite materials of the present invention is given below.[0022]

I. Abrasive Webs and Nonwoven Composite Components[0023]

The abrasive webs and nonwoven composite materials of the present invention may comprise one or more layers of material, wherein each layer contributes at least one desired property to the resulting abrasive web or nonwoven composite material. Suitable layers and layer components for forming the abrasive webs and nonwoven composite materials of the present invention are described below.[0024]

A. An Abrasive Layer of Meltblown Fibers[0025]

The abrasive webs and nonwoven composite materials of the present invention desirably comprise at least one abrasive layer of meltblown fibers. In one exemplary embodiment of the present invention, the abrasive web comprises a single layer of meltblown fibers. The layer of meltblown fibers is a nonwoven fabric. In other words, the single layer of meltblown fibers possesses enough structural integrity to form a nonwoven fabric, which may exist as a nonwoven fabric without the need for a supporting substrate. The meltblown fibers may be (1) autogenously bonded to one another, (2) bonded to one another using an external source of heat and/or pressure, or (3) both (1) and (2). As used herein, the term “autogenously bonded” is used to describe fibers, which bond to one another as the fibers come into contact with one another after leaving an extrusion die.[0026]

The fibers of the abrasive meltblown fabric layer may be made from a variety of materials depending on a number of factors including, but not limited to, processability of the fiber-forming material, desired properties of the individual web and the resulting composite material, and manufacturing costs. Suitable fiber-forming materials include, but are not limited to, polypropylene, polybutylene, polyethylene terephthalate, polyamide, and combinations thereof. Desirably, the fibers of the abrasive meltblown fabric layer comprise polypropylene. Commercially available polypropylenes suitable for use in the present invention include, but are not limited to, polypropylene available from Basell Polyolefins (Wilmington, Del.) under the trade designation Basell. In one desired embodiment of the present invention, the fibers of the abrasive meltblown fabric layer comprise polypropylene fibers formed from polypropylene available from Basell Polyolefins (Wilmington, Del.) under the trade designation Basell, and having a melt flow index of about 800 g/10 min as measured according to ASTM D-1238.[0027]

Desirably, the fibers of the abrasive meltblown fabric layer have an average fiber diameter of less than about 100 microns. More desirably, the fibers have an average fiber diameter of from about 0.5 micron to about 40 microns. Even more desirably, the fibers have an average fiber diameter of from about 10 micron to about 35 microns.[0028]

The abrasive meltblown fabric layer may have a basis weight, which varies depending upon the particular end use of the individual web and the resulting composite material. Desirably, the abrasive meltblown fabric layer has a basis weight of less than about 500 grams per square meter (gsm) prior to stretching. More desirably, the abrasive meltblown fabric layer has a basis weight of from about 2.5 gsm to about 500 gsm prior to stretching. Even more desirably, the abrasive meltblown fabric layer has a basis weight of from about 8 gsm to about 100 gsm prior to stretching, even more desirably from about 28 gsm to about 60 gsm prior to stretching.[0029]

As with the basis weight, the abrasive meltblown web may have a thickness, which varies depending upon the particular end use of the individual web and the resulting composite material. Desirably, the abrasive meltblown web has a thickness of less than about 1000 microns (μm) prior to stretching. More desirably, the abrasive meltblown web has a thickness of from about 10 μm to about 500 μm prior to stretching. Even more desirably, the abrasive meltblown web has a thickness of from about 20 μm to about 100 μm prior to stretching.[0030]

In most embodiments, the fibers within the abrasive meltblown web are uniformly distributed within the web. However, there may be some embodiments wherein it is desirable to have a non-uniform distribution of fibers within the abrasive meltblown web.[0031]

B. Absorbent Layer of Nonwoven Fibers[0032]

The composite materials of the present invention may further comprise an absorbent layer in the form of an additional nonwoven fabric. Suitable nonwoven fabric layers include, but are not limited to, a meltblown fabric layer, a spunbonded fabric layer, a spunlaced fabric layer, a carded thermally-bonded (or ‘point-bonded’) nonwoven containing a percentage of viscose fibers or other hydrophilic fiber, or a combination thereof. Desirably, the absorbent layer comprises a meltblown fabric layer or a spunbonded fabric layer.[0033]

The fibers of the absorbent nonwoven fabric layer may be made from a variety of materials depending on a number of factors including, but not limited to, processability of the fiber-forming material, desired properties of the individual web and the resulting composite material, and manufacturing costs. Desirably, the fibers of the absorbent nonwoven fabric layer any of the above-mentioned fiber-forming materials.[0034]

When the absorbent layer comprises a meltblown fabric layer, the fibers of the absorbent meltblown fabric layer desirably have an average fiber diameter of less than about 100 microns. More desirably, the fibers of the absorbent meltblown fabric layer have an average fiber diameter of from about 0.5 micron to about 40 microns. Even more desirably, the fibers have an average fiber diameter of from about 1 micron to about 30 microns.[0035]

Further, when the absorbent layer comprises a meltblown fabric layer, the meltblown fabric layer desirably has a basis weight of less than about 1000 grams per square meter (gsm) prior to stretching. More desirably, the absorbent meltblown fabric layer has a basis weight of from about 25 gsm to about 500 gsm prior to stretching. Even more desirably, the absorbent meltblown fabric layer has a basis weight of from about 30 gsm to about 100 gsm prior to stretching.[0036]

As with the basis weight, the absorbent meltblown fabric layer may have a thickness, which varies depending upon the particular end use of the composite material. Desirably, the absorbent meltblown fabric layer has a thickness of less than about 1000 microns (μm) prior to stretching. More desirably, the absorbent meltblown fabric layer has a thickness of from about 10 μm to about 500 μm prior to stretching. Even more desirably, the absorbent meltblown fabric layer has a thickness of from about 20 μm to about 100 μm prior to stretching.[0037]

As discussed above, the absorbent nonwoven fabric layer may comprise nonwoven fabric layers other than a meltblown fabric layer. In one desired embodiment, the absorbent nonwoven fabric layer comprises a spunbonded fabric layer having fiber dimensions, fabric basis weight, and fabric thickness values similar to the values given above with regard to the absorbent meltblown fabric layer.[0038]

C. Absorbent Layer of Woven Fibers[0039]

In addition to or as an alternative to the absorbent nonwoven layer, the composite materials of the present invention may comprise an absorbent layer in the form of a woven fabric. Suitable woven fabric layers include, but are not limited to, woven fabrics formed from absorbent fibers, hydrophilic fibers, or a combination thereof. The fibers of the absorbent woven fabric layer may be made from any of the above-described materials. Further, the absorbent woven fabric layer may include cellulosic fibers, cotton fibers, viscose fibers, or any other absorbent or hydrophilic fiber.[0040]

Further, when the absorbent layer comprises a woven fabric layer, the woven fabric layer desirably has a basis weight of less than about 1000 grams per square meter (gsm) prior to stretching. More desirably, the absorbent woven fabric layer has a basis weight of from about 25 gsm to about 500 gsm prior to stretching. Even more desirably, the absorbent woven fabric layer has a basis weight of from about 30 gsm to about 100 gsm prior to stretching.[0041]

As with the basis weight, the absorbent woven fabric layer may have a thickness, which varies depending upon the particular end use of the composite material. Desirably, the absorbent woven fabric layer has a thickness of less than about 1000 microns (μm) prior to stretching. More desirably, the absorbent woven fabric layer has a thickness of from about 10 μm to about 500 μm prior to stretching. Even more desirably, the absorbent woven fabric layer has a thickness of from about 20 μm to about 100 μm prior to stretching.[0042]

D. Additives[0043]

In addition to the fiber-forming materials mentioned above, various additives may be added to the fiber melt and extruded to incorporate the additive into the fiber. Alternatively, one or more additives may be coated onto the fiber during or after the fabric forming process. Suitable additives include, but are not limited to, fillers, stabilizers, plasticizers, tackifiers, flow control agents, cure rate retarders, adhesion promoters (for example, silanes and titanates), adjuvants, impact modifiers, expandable microspheres, thermally conductive particles, electrically conductive particles, and the like, such as silica, glass, clay, talc, pigments, colorants, scent-producing agents, surfactants, detergents, glass beads or bubbles, antioxidants, optical brighteners; antimicrobial agents; surfactants; fire retardants; and fluoropolymers. Typically, the amount of one or more additives is less than about 25 weight percent, desirably, up to about 2.5 percent, based on the total weight of the fiber and/or fabric.[0044]

One or more of the above-described additives may be used to reduce the weight and/or cost of the resulting fiber and/or web, adjust viscosity, or modify the thermal properties of the fiber or confer a range of physical properties derived from the physical property activity of the additive including: cleansing properties,antimicrobial properties, scent-producing properties, color-producing properties, etc.[0045]

In one desired embodiment of the present invention, at least one colorant and at least one scent-producing additive are added to or coated onto the fiber-forming materials of the abrasive meltblown layer and/or the at least one additional fabric layer. In one exemplary embodiment, the fiber-forming materials of the abrasive meltblown layer are substantially free of colorants and scent-producing additives, while the fiber-forming materials of the at least one additional fabric layer contains at least one colorant and at least one scent-producing additive. In another exemplary embodiment, the fiber-forming materials of the abrasive meltblown layer contain at least one colorant and/or at least one scent-producing additive, while the fiber-forming materials of the at least one additional fabric layer are substantially free of colorants and scent-producing additives. Desirably, the colorant, when present, comprises a pigment or dye providing a desired color, such as yellow, orange, or any other desired color. Desirably, the scent-producing additive, when present, provides a desired scent, such as a lemon scent, a pine scent, or any other desired scent. One example of a suitable scent-producing additive is Lemon Citrus #50-3264 commercially available from Cognis Corporation (Ambler, Pa.).[0046]

In a further desired embodiment of the present invention, at least one layer of the composite material comprises a soap, surfactant or detergent. The terms “soap”, “surfactant” and “detergent” are used herein to describe materials for cleaning a surface, such as cookware, utensils, countertop, or any other surface. For example, a surfactant may be added to the fiber-forming material of the abrasive layer and/or the additional fabric layer before the abrasive layer and/or the additional fabric layer is formed to make the abrasive layer and/or the additional fabric layer more hydrophilic. Alternatively or additionally, a surfactant may be applied to the fiber-forming materials of the abrasive layer and/or the additional fabric layer after the abrasive layer and/or the additional fabric layer is formed. In addition to a surfactant, one or more antimicrobial agents, such as silver zeolite, may also be incorporated into the abrasive layer and/or the additional fabric layer.[0047]

A variety of hydrophilic additives, soaps, surfactants and detergents may be used in the present invention. Suitable surfactants include, but are not limited to, nonionic surfactants, anionic surfactants, and a combination thereof. One example of a suitable hydrophilic additive is polyethylene glycol. One example of a suitable detergent is Detergent 0240-82 commercially available from Cognis Corporation (Ambler, Pa.).[0048]

II. Methods of Making Bonded Composites[0049]

The composite components described above may be used to prepare a bonded composite, which may be used as a precursor to the stretched composite materials of the present invention. Exemplary composite material components are shown in FIG. 1. As shown in FIG. 1, exemplary[0050]composite material 10 comprises anabrasive web 11 including extrudedpolypropylene fibers 15 and an additionalnonwoven material 12 comprising extrudedpolypropylene fibers 16.

An exemplary bonded composite is shown in FIG. 2. The exemplary bonded[0051]composite 10 of FIG. 2 comprisesupper layer 11 bonded tolower layer 12. For example,upper layer 11 may be an abrasive meltblown nonwoven fabric of polypropylene fibers, andlower layer 12 may be a second meltblown nonwoven fabric of polypropylene fibers. Althoughupper layer 11 may be bonded tolower layer 12 using a variety of bonding processes as described below, exemplary bondedcomposite 10 of FIG. 2 comprisespoint bonds 13 uniformly distributed along anupper surface 110 ofupper layer 11.

FIG. 3 depicts a cross-sectional view of exemplary bonded[0052]

composite

10 of FIG. 2 along line A-A. As shown in FIG. 3, bondedcomposite10 has an overall thickness, which is the combined thickness ofupper layer11 andlower layer12. As used herein, the term “overall thickness” when used to describe the thickness of bondedcomposite10 describes the average thickness of the bondedcomposite10 in areas other than point-bondedareas13. Typically, bondedcomposite10 has an overall thickness of from about 40 microns (μm) to about 250 μm prior to stretching. Desirably, bondedcomposite 10 has an overall thickness of from about 60 μm to about 110 μm prior to stretching.

The bonded composite may be prepared in a number of ways. One exemplary method of making a meltblown web for use in the bonded composite is depicted in FIG. 4.[0053]

As shown in FIG. 4,[0054]

molten polymer

300 is introduced into adie assembly320. Dieassembly320 comprises a plurality of spinnerets (not shown) from whichmolten polymer300 is extruded.Molten polymer300 exits die assembly320 atlocation325 and enters into a curtain ofprocess air330. The curtain ofprocess air330 attenuates extrudedpolymer fibers350 as thefibers350 travel a distance d from an exit of the plurality of spinnerets (not shown) to a collection surface atlocation360 on an outer surface ofdrum365.Drum365 rotates at a desired speed to form ameltblown web370, which moves along an outer surface ofdrum365.Meltblown web370 moves alongdrum365 to point366, wherein a niproll367 contacts themeltblown web370 and guides the web off ofdrum365 onto an outer surface of niproll367.Meltblown web370 may proceed onto other processes along the process line, such as acalender assembly380.

[0055]

Calender assembly

380 comprises afirst roll381 and asecond roll382 which nip themeltblown web370 to further bond the fibers of the web to one another.First roll381 andsecond roll382 may have a smooth surface to form bonding sites throughoutmeltblownweb370. Alternatively, at least one offirst roll381 andsecond roll382 has raised portions along the roll surface, which results in a point-bonding pattern across meltblown web370 (such as the point-bonding shown in FIGS.2-3). Each point of the point-bonding pattern may have any shape and size desired. The total bonded area of themeltblown web370 may vary from about 5 to about 95 percent of the total surface area of the web, desirably, from about 8 to about 50 percent of the total surface area of the web, more desirably, from about 25 to about 40 percent of the total surface area of the web.

The resulting[0056]

meltblown web

370 may be taken off the process line in the form of a roll, such as on a cardboard or plastic tube, and stored for later processing. Alternatively, resulting meltblown web370 may be further processed by joiningmeltblown web370 to another composite component layer, such as an additional nonwoven fabric layer, and then processed through a bonding process, such as the above-described calendering process.

Desirably, an additional composite component layer, such as an additional nonwoven fabric layer, is joined to[0057]

meltdown web

370 as shown in FIG. 5. As meltblown web370 (also referred to as meltblown layer12) leaves niproll367 and proceeds towardcalender assembly380,meltblown web370 is brought into contact with a pre-manufactured abrasivemeltblown fabric layer11. The combinedmeltblown web370/abrasivemeltblown fabric layer11 assembly proceeds throughcalender assembly380 to produce bondedcomposite material10. It should be noted that the pre-manufactured abrasivemeltblown fabric layer11 may be prepared using a process as shown in FIG. 4. Further, it should be noted that a woven fabric (not shown) may be joined to a pre-manufactured abrasivemeltblown fabric layer11 and processed throughcalender assembly380 to produce a bonded composite material.

When a point-bonding process is used to join the meltblown web[0058]370 (or a woven fabric) to an additional nonwoven fabric layer, it is desirable for the bonded pre-stretched composite material to have a bond cover area of less than about 50% based on a total surface area of the bonded pre-stretched composite material. More desirably, the bonded pre-stretched composite material has a bond cover area of from about 30% to about 40% based on a total surface area of the bonded pre-stretched composite material.

One alternative method of forming a bonded[0059]

composite material

10 is shown in FIG. 6. As thefibers350 travel a distance d from an exit of the plurality of spinnerets (not shown) to the collection surface atlocation360 on an outer surface ofdrum365, a second substrate12 (e.g., a pre-manufactured absorbent nonwoven or woven fabric layer) is brought into contact with the plurality offibers350.Second substrate12 can be stored inroll form340. Incalender assembly380,first roll381 andsecond roll382 bond the fibers ofmeltblown web370 to one another and alsobond meltblown web370 tosecond substrate12 to form bonded pre-stretchedcomposite material10. The degree of bonding withinmeltblown web370 and tosecond substrate12 may vary as described above.

Typically, the method of forming the meltblown web involves melt extruding a thermoformable material at a melt extrusion temperature of from about 130° C. to about 350° C. In particular, for polypropylene fibers, the polypropylene is melt extruded at a melt extrusion temperature of about 270° C.[0060]

The die assembly comprises a plurality of spinnerets through which molten thermoformable material is extruded. Desirably, the die assembly comprises a plurality of spinnerets, wherein the number of spinneret holes through the die is at least 700 spinneret holes per linear meter. Typically, the plurality of spinnerets has an average hole diameter of from about 0.25 to about 0.75 mm.[0061]

Desirably, the method of making the meltblown web comprises melt extruding a thermoformable material, such as polypropylene, at a rate of at least 25 kilograms per hour per linear meter of extrusion width (k/hr/lm). In one embodiment, the weight of extruded polymer per orifice of die is from about 0.3 g of polymer per hole per minute to about 2.0 g of polymer per hole per minute.[0062]

Desirably, the method of making the meltblown web comprises using a stream of air to attenuate the plurality of extruded fibers at a point below an exit of the plurality of spinnerets within the die assembly. The exit of the plurality of spinnerets may be positioned a distance, d, above the collection surface. In one embodiment of the present invention, the distance, d, may be adjusted by moving the plurality of spinnerets up or down relative to the collection surface. This may be beneficial for control of fiber size, web pore size, fiber fusion, and web basis weight uniformity. Desirably, distanced, may vary from about 100 mm to about 1500 mm.[0063]

The stream of air used to attenuate the plurality of extruded fibers desirably has an air speed of from about 5 meters per second (ms[0064]⁻¹) to about 300 ms⁻¹. The air stream volume typically ranges from about 550 cm³/sec per centimeter (cm) of die width (3 cfm per inch of die width) to about 1860 cm³/sec per centimeter (cm) of die width (10 cfm per inch of die width), desirably about 1100 cm³/sec per centimeter (cm) of die width (6 cfm per inch of die width). Further, the stream of air desirably has an air temperature of from about 150° C. to about 400° C., more desirably, from about 160° C. to about 240° C., and even more desirably about 200° C.

In one embodiment of the present invention, the method uses a die assembly comprising a plurality of spinnerets wherein the plurality of spinnerets are arranged along a die having a length,l, and a width, w, with an upper surface (i.e., die entrance), a lower surface (i.e., die exit), two side surfaces, and two end surfaces. Typically, the die assembly has a length, 1, of from about 0.05 meters (m) to about 3 m extending in a first direction perpendicular to the web (i.e., the cross direction of the web); and a width, w, of from about 1 mm to about 100 mm extending in a second direction parallel to the web (i.e., the machine direction of the web). A plurality of spinneret holes extends in a direction from the upper surface to the lower surface. A stream of attenuating air may contact the plurality of fibers at a point below an exit of the plurality of spinnerets, wherein the stream of air flows through slots positioned along the two side surfaces (see FIGS.[0065]4-6).

It should be noted that the collection surface may be in the form of a flat surface as oppose to a rotating drum (as shown in FIGS.[0066]4-6). The collection surface may comprise a drum supporting a carrier material; an endless belt, a horizontal table; a horizontal table supporting a carrier material; or a tenter frame supporting a carrier material.

Desirably, the collection surface is a drum having a diameter of from about 0.3 m to about 2.0 m, and a width of from about 0.05 m to about 3 m. The drum may have an outer surface comprising a smooth metal surface or a wire screen mesh. Desirably, the drum has an outer surface comprising a wire screen mesh.[0067]

The drum outer surface may be of any appropriate material, such as metal, polyester or teflon. In one desired embodiment, the drum outer surface is a wire screen mesh having an x-y matrix pattern with gaps in between the wire mesh material. Any gauge wire mesh material may be used as long as the meltblown web that is formed on the wire mesh material maintains a sufficient amount of integrity and strength after being removed from the wire mesh material.[0068]

The speed of the drum may vary depending on the throughput of the process line. Desirably, an outer surface of the drum has a linear speed of from about 0.1 μm/min to about 150 m/min.[0069]

The method of forming the bonded pre-stretched composite may include any of the above-described features. In addition, the method of forming the bonded pre-stretched composite may include one or more of the following process steps:[0070]

(1) rotating the drum to advance the meltblown web along an outer surface of the drum;[0071]

(2) nipping the meltblown web between a nip roll and the drum, wherein the web separates from the drum at a nip point and follows a web path along an outer surface of the nip roll;[0072]

(3) coating the bonded pre-stretched composite with a surface treatment;[0073]

(4) attaching the bonded pre-stretched composite to a cardboard or plastic tube;[0074]

(5) taking-up the bonded pre-stretched composite in the form of a roll; and[0075]

(6) slitting the bonded pre-stretched composite to form two or more slit rolls.[0076]

III. Methods of Making Stretched Composite Materials[0077]

The bonded composite may be further processed through a stretching apparatus, such as the exemplary stretching apparatus shown in FIG. 7A. As shown in FIG. 7A, bonded composite[0078]10 proceeds through stretchingapparatus60 and exits as stretchedcomposite material395. Stretchingapparatus60 comprises two interengaged drums,upper drum61 andlower drum62, and anip roller63. Each drum consists of alternating discs having different disc diameters. A cross-sectional view ofupper drum 61 andlower drum 62 is given in FIG. 7B.

As shown in FIG. 7B,[0079]

upper drum

61 consists of alternating

discs

612 and613 having a larger disc diameter, d₆₁₂, and a smaller diameter, d₆₁₃, respectively.Lower drum62 also consists of alternating

discs

615 and616 having a larger disc diameter, d₆₁₅, and a smaller diameter, d₆₁₆, respectively. As bonded composite10

approaches stretching apparatus

60, tension is exerted on bondedcomposite10 bynip roller63 to keep bonded composite10 positioned next tolower drum62. As bonded composite10 proceeds through stretchingapparatus60, a stretching force is exerted on bonded compositelo so as to stretch bonded composite10 in specific areas referred to herein as “microstretched portions.” The microstretched portions extend in the machine direction of the stretchedcomposite material395, and are located substantially between adjacent peaks and valleys as described below.

As shown in FIG. 7B,[0080]

discs

612 onupper drum61 exert a stretching force on bondedcomposite10, forcing portions of bonded composite10 into the gaps betweendiscs615 onlower drum62.Peaks82 andvalleys84 are formed in bondedcomposite10. The areas betweenpeaks82 andvalleys84 aremicrostretched portions86. It is believed that a substantial amount of the total stretching of bondedcomposite10 occurs inmicrostretched portions86. The distance betweenpeaks82 and valleys84 (and the length ofmicrostretched portions86 as measured in the cross direction of bonded compositely) may vary depending on the width and diameters of discs612,613,615 and616. Further, it is believed thatpeaks82 andvalleys84 have a higher concentration of bonds between the composite material layers (e.g.,upper layer11 and lower layer12) compared to a bond concentration in themicrostretched portions86.

Typically,[0081]

discs

612,613,615 and616 have a width ranging from about 0.5 mm (20 mil.) to about 3.0 mm (120 mil.), desirably, from about 1.0 mm (40 mil.) to about 1.5 mm (60 mil.). In one exemplary embodiment of the present invention,

discs

612,613,615 and616 have the following widths: disc612-1.27 mm (50 mil.); disc613-2.54 mm (100 mil.); disc615-1.27 mm (50 mil.); and disc 616-2.54 mm (100 mil.).

Typically,[0082]

discs

612,613,615 and616 have a diameter ranging from about 5.1 cm (2 inches (in.)) to about 61.0 cm (24 in.), desirably, from about 7.6 cm (3 in.) to about 30.5 cm (12 in.). In one exemplary embodiment of the present invention, discs612,613,615 and616 have the following diameters: disc612-17.8 cm (7 in.); disc613-15.2 cm (6 in.); disc615-17.8 cm (7 in.); and disc616-15.2 cm (6 in.).

One suitable stretching apparatus for stretching the bonded pre-stretched composite is disclosed in U.S. Pat. No. 4,368,565 assigned to Biax-Fiberfilm Corporation (Neenah, Wis.), the entire content of which is hereby incorporated by reference.[0083]

The bonded composite may be laterally stretched using the above-describe stretching apparatus to increase the width of the bonded composite up to about 30% (i.e., the final width is 1.3 times the original width). Desirably, the bonded composite is laterally stretched to a final width, which is from about 2% to about 25% greater than the original width of the bonded pre-stretched composite, more desirably, from about 10% to about 25% greater than the original width of the bonded pre-stretched composite.[0084]

It should be noted that any single layer of the composite material of the present invention may be laterally stretched using the above-describe stretching apparatus prior to being joined to one or more other layers of the composite material. For example, an absorbent layer may be stretched to increase the width of the absorbent layer up to about 30% (i.e., the final width is 1.3 times the original width) prior to joining the absorbent layer to an abrasive nonwoven layer. Typically, prior to being stretched, the absorbent layer is calendered as described above, although calendering is an optional step. After stretching the absorbent layer, the stretched absorbent layer may be joined to the abrasive nonwoven layer to form the composite material. The resulting composite material may be further processed as described below.[0085]

In one desired embodiment of the present invention, the composite material comprises (i) a calendered, stretched absorbent layer comprising a meltblown or spunbonded nonwoven fabric, and (ii) an abrasive nonwoven fabric layer bonded to the stretched absorbent layer. In this embodiment, the absorbent layer is desirably laterally stretched to a final width, which is from about 2% to about 25% greater than the original width of the absorbent layer, more desirably, from about 10% to about 25% greater than the original width of the absorbent layer. The abrasive layer may be either (i) point-bonded to the stretched absorbent layer at a desired bond cover area of from about 30% to about 40% based on a total surface area of the bonded composite material, or (ii) overblown onto the stretched absorbent layer (using the meltblowing process described above and depicted in FIG. 6) to produce a composite material. Desirably, the abrasive layer is overblown onto the stretched absorbent layer to produce a composite material.[0086]

IV. Methods of Making Composite Materials Containing One or More Additives[0087]

As described above, one or more additives may be incorporated into one or more layers of the composite material of the present invention. The one or more additives may be incorporated into an individual layer of the composite material prior to being bonded to one or more additional layers of the composite material. Alternatively, one or more additives may be incorporated into each of the individual layers of the composite material after being bonded to one another.[0088]

In one embodiment of the present invention, one or more additives, such as a colorant, a scent-producing agent, and/or a surfactant, are sprayed onto the fibers as the fibers travel distanced, between (i) the exit of the plurality of spinnerets and (ii) the collection surface (see FIGS.[0089]4-6). In an alternative embodiment, one or more additives, such as a colorant, a scent-producing agent, and/or a surfactant, are coated onto and/or impregnated into the composite material. The coating process may be any known coating process, such as a spray coating, pad coating, dip coating, etc. One method of impregnating one or more additives into the composite material is via an extrusion process, wherein the composite material is passed through an extrusion die having a width and height similar to or slightly larger than the dimensions of the composite material. In this embodiment, one or more additives are fed into the extruder as the composite material travels through the extruder, resulting in an impregnation of the composite material.

In a further embodiment of the present invention, one or more additives may be incorporated into the polymer melt prior to fiber formation. In this embodiment, the one or more additives are typically in the form of finely divided solid particles, which may be blended with the polymer. The particle size is small relative to the die orifices used to extrude the fiber-forming material.[0090]

V. Stretched Composite Materials[0091]

The stretched composite materials of the present invention may have a cross-sectional configuration along a cross direction of the composite, which varies depending on the stretching apparatus used. As used herein, the term “stretched composite materials” refers to composite materials of the present invention wherein (i) the entire composite material is stretched or (ii) at least one layer of the composite material (e.g., the absorbent layer) is stretched using the method as described above. In one exemplary embodiment of the present invention, the stretched composite material has a wave-like cross-sectional configuration along a cross direction of the stretched composite material, wherein the wave-like cross-sectional configuration contains a plurality of alternating peaks and valleys. Exemplary wave-like cross-sectional configurations are shown in FIGS. 8A and 8B.[0092]

As shown in FIGS. 8A and 8B, stretched[0093]

composite material

395 may have a sine-wave shape (FIG. 8A) or a truncated cone-wave shape (FIG. 8B). It should be noted that stretchedcomposite material395 may have other cross-sectional configurations depending on the shape and dimensions of the alternating discs used to stretch the composite material. In FIGS. 8A and 8B, stretchedcomposite material395 haspeaks82,valleys84, andmicrostretched portions86 positioned betweenpeaks82 andvalleys84. In a desired embodiment of the present invention, the microstretched portions86 extend in the machine direction of stretchedcomposite material395, and are located substantially betweenadjacent peaks82 andvalleys84.

As shown in FIG. 8B, stretched[0094]

composite material

395 may have a cross-sectional configuration, wherein each peak82 is separated from adjacent peaks as viewed along the cross direction of stretchedcomposite material395 and located substantially within a first plane. Likewise, eachvalley84 may be separated from adjacent valleys as viewed along the cross direction of stretched composite material395 and located substantially within a second plane parallel with and below the first plane. The microstretched portions86 are located substantially between the first plane and the second plane. In one embodiment of the present invention, stretchedcomposite material395 have a cross-sectional configuration, wherein the average distance between adjacent peaks ranges from about 1.0 mm to about 10.0 mm, and the average distance between adjacent valleys ranges from about 1.0 mm to about 10.0 mm. As used herein, the term “distance between adjacent peaks” refers to the distance between the apex of one peak and the apex of an adjacent peak. Desirably, the average distance between adjacent peaks ranges from about 2.0 mm to about 6.0 mm, and the average distance between adjacent valleys also ranges from about 2.0 mm to about 6.0 mm.

In a further embodiment of the present invention, stretched[0095]

composite material

395 has a cross-sectional configuration, wherein themicrostretched portions86 have an average width as measured along the cross direction of stretchedcomposite material395 between the first plane and the second plane ranging from about 0.05 mm to about 8.0 mm, more desirably, from about 1.0 mm to about 3.0 mm.

It should be understood that when the stretched composite material of the present invention comprises a stretched layer (e.g., a stretched absorbent layer) and an unstretched layer (e.g., an abrasive nonwoven layer), the composite material may still have any of the above-described cross-sectional configurations having peaks and valleys as described above. However, the above-described microstretched portions will only be present within the stretched layer of the composite material.[0096]

As discussed above, the stretched composite materials of the present invention may have a final width of at least 2% greater than the bonded pre-stretched composite. Further, the stretched composite materials of the present invention (or a stretched layer thereof) may have a final thickness of at least 20% greater than the pre-stretched composite material (or pre-stretched layer). Desirably, the stretched composite material (or a stretched layer thereof) has a final thickness of from about 30% to about 60% greater than the pre-stretched composite material (or pre-stretched layer), more desirably, from about 35% to about 50% greater than the pre-stretched composite material (or pre-stretched layer).[0097]

Desirably, the stretched composite material (or a stretched layer of the composite material) has the following properties:[0098]

(1) an overall thickness at least 40% greater than a pre-stretched thickness of the composite material (or composite layer);[0099]

(2) an absorbency of at least 20% greater than the pre-stretched absorbency of the composite material (or composite layer).[0100]

VI. Uses For Stretched and Pre-Stretched Composite Materials[0101]

The stretched and pre-stretched composite materials of the present invention may be used in a variety of applications including residential, commercial (e.g., food service businesses), and industrial applications. The stretched and pre-stretched composite materials of the present invention are particularly useful as materials for forming wipes. The wipes may be used for cleaning pots and pans, as well as, surface cleaning for bathrooms, outdoor camping, recreational vehicles, etc. The wipes may also be cut to a suitable dimension for use in gun cleaning applications.[0102]

In one exemplary embodiment of the present invention, the stretched composite material is formed into a wipe. The wipe comprises an outer layer of an abrasive meltblown nonwoven fabric and at least one absorbent nonwoven fabric bonded to the abrasive meltblown nonwoven fabric. The wipe may have any desired size and shape. Typically, the wipes are available as separate individual sheets or as connected individual sheets in roll form, similar to a roll of paper towels, wherein the individual sheets have a width and/or length of up to about 50 cm. In one exemplary roll of wipes, each individual wipe has a width of about 28 cm and a length of about 22 cm.[0103]

Desirably, the wipe comprises (a) an abrasive meltblown nonwoven fabric formed from polypropylene fibers having an average fiber diameter of less than about 100 microns and a fabric basis weight of from about 28 gsm to about 60 gsm; and (b) at least one additional meltblown nonwoven fabric formed from polypropylene fibers having an average fiber diameter of less than about 100 microns and a fabric basis weight of from about 44 gsm to about 100 gsm. In one desired embodiment, the wipe comprises (a) an abrasive meltblown fabric layer of extruded polypropylene fibers having a basis weight of about 34 gsm and an average fiber diameter ranging from about 10 μm to about 32 μm calendared to (b) an absorbent meltblown nonwoven fabric of extruded polypropylene fibers having an average fiber diameter of from about 2 μm to about 10 μm.[0104]

The wipe material is desirably calendered at a point-bonding density of about 33% (i.e., about 33% of the total surface area of an outer layer of the composite wipe material is bonded) to form pockets within the layers of the composite material (i.e.,[0105]point bonds 13 as shown in FIG. 2). The pockets allow the composite wipe material to collect dirt or other particles from a surface being wiped. As an abrasive force is applied to the surface, dirt or other particles are released from the surface. The capture of particles in the wipe pockets allows the particles to move away from the surface, which reduces scratching or damaging of the surface being wiped. Furthermore, it is believed that the pockets increase the durability and life-span of the composite wipe material.

The above-described calendering step results in a plurality of pockets uniformly distributed over the composite or wipe material, wherein each pocket desirably has a pocket lip and a pocket floor (see FIG. 3, which depicts[0106]

pocket lip

131 and pocket floor132). The pocket lips are desirably positioned along an outer surface of the abrasive layer while the pocket floors are positioned within an interior of the composite material, desirably within the additional nonwoven fabric layer. The plurality of pockets may be uniformly distributed in an amount depending on the size and shape of the pockets. In one exemplary embodiment, the plurality of pockets are uniformly distributed in an amount of about 25 pockets per square centimeter of outer surface of the abrasive layer, wherein each pocket has a substantially square or diamond shape having a pocket surface area of about 1 square millimeter. However, it should be understood that the size, shape, and number of pockets per given area of composite material may vary as desired.

Desirably, the wipe comprises at least one of (i) a colorant, (ii) a scent-producing additive, (iii) a surfactant, and (iv) an antimicrobial agent in (a) the abrasive layer, (b) the absorbent nonwoven and/or woven layer, or both. In one desired embodiment, the wipe comprises a colorant (e.g., yellow) in the abrasive layer, and both a scent-producing additive (e.g., lemon scent) and a surfactant in the absorbent meltblown nonwoven layer. In a further desired embodiment, the wipe comprises an abrasive layer substantially free of additives, and an absorbent meltblown nonwoven layer comprising a colorant (e.g., yellow), a scent-producing additive (e.g., lemon scent), and a surfactant.[0107]

The wipe may be used in residential, commercial, or industrial applications. The presence of a surfactant impregnated into the wipe enables the wipe to produce a cleaning foam composition once the wipe is exposed to water. The wipe provides an abrasive cleaning surface and surfactant composition, which is safe to use on teflon-coated cookware, as well as, other scratch-sensitive surfaces, such as porcelain surfaces and painted surfaces.[0108]

In a further exemplary embodiment of the present invention, the pre-stretched composite material (i.e., no layers in the composite material are stretched) is formed into a wipe. The wipe comprises an outer layer of an abrasive meltblown nonwoven fabric and at least one absorbent nonwoven fabric bonded to the abrasive meltblown nonwoven fabric. As with the stretched composite wipe described above, the pre-stretched composite wipe may have any desired size and shape, and may be available as separate individual sheets or as connected individual sheets in roll form, similar to a roll of paper towels. In one exemplary embodiment, the pre-stretched composite wipes are available as separate individual sheets, wherein each individual wipe has a width of about 33 cm and a length of about 29.7 cm.[0109]

The present invention is described above and further illustrated below by way of examples, which are not to be construed in any way as imposing limitations upon the scope of the invention. On the contrary, it is to be clearly understood that resort may be had to various other embodiments, modifications, and equivalents thereof which, after reading the description herein, may suggest themselves to those skilled in the art without departing from the spirit of the present invention and/or the scope of the appended claims.[0110]

TEST METHODS

The following test methods were used to evaluate composite materials of the present invention.[0111]

Softness Testing:[0112]

Softness is determined using a drapeability test. Samples of fabric are cut into 2.54 cm (1 in.)×12.7 cm (5 in.) strips. Samples are taped to the edge of a flat, level surface so that the sample hangs over the edge of the surface. The distance from the surface to the hanging edge of the strip is measured. A longer distance measurement indicates a softer and more drapeable fabric sample.[0113]

Absorbency Testing.[0114]

Samples are cut into 12.7 cm (5 in.) diameter circles. The dry samples are weighed. The dry weight is recorded. The samples are immersed in a water bath for 10 minutes. Samples are then allowed to drain on a rack for 10 minutes. The wet samples are weighed. The wet weight is recorded. The absorbency is expressed in percentage dry weight.[0115]

Resistance to Water Penetration Testing:[0116]

The hydrohead test method measures the resistance of a fabric to the penetration of water under low hydrostatic pressure. The method is performed by applying a fabric sample to the top of a test head reservoir. Water pressure is increased at a constant rate until water leaks through the fabric sample. The water pressure is read at the first sign of leakage in three separate areas of the sample. Water pressure is reported in units of psi or mbar. Details of this test method are described in INDA test method, IST 80.6 (01)-Standard Test Method for Water Resistance, The Hydrostatic Pressure Test.[0117]

EXAMPLE 1Preparation of an Abrasive Meltblown Web

A fiber-producing melt was prepared by melting a fiber composition comprising polypropylene at a melt temperature of about 270° C. The polymer melt was extruded a rate of 100 kilograms per hour per linear meter of extrusion width (kg/hr/lm) using an apparatus similar to the apparatus as shown in FIG. 4. The molten polymer was introduced into a die assembly having a height of 0.13 m, a width of 0.15 m, and a length of 1 m, and comprising a plurality of spinnerets having a hole diameter of 0.305 mm, wherein the number of spinneret holes through the die was 1378 spinneret holes per linear meter.[0118]

The molten polymer exited the die assembly and entered into a curtain of process air having an air temperature of 260° C. and an air speed of 366 cfm. The curtain of process air attenuated the extruded fibers as the fibers traveled a distance d (d=230 mm) from an exit of the plurality of spinnerets to a collection surface on an outer surface of a rotating drum having an outer diameter of 0.66 m. The drum was rotating with a linear speed of 40 m/min.[0119]

The plurality of fibers moved along an outer surface of the rotating drum having a wire screen contact surface. The formed web was removed from the drum by a nip roll assembly.[0120]

EXAMPLE 2Preparation of an Absorbent Meltblown Web

A fiber-producing melt was prepared by melting a fiber composition comprising polypropylene at a melt temperature of about 270° C. The polymer melt was extruded a rate of 100 kilograms per hour per linear meter of extrusion width (kg/hr/lm) using an apparatus similar to the apparatus as shown in FIG. 4. The molten polymer was introduced into a die assembly having a height of 0.13 m, a width of 0. 15 m, and a length of 1 m, and comprising a plurality of spinnerets having a hole diameter of 0.305 mm, wherein the number of spinneret holes through the die was 1378 spinneret holes per linear meter.[0121]

The molten polymer exited the die assembly and entered into a curtain of process air having an air temperature of 260° C. and an air speed of 366 cfm. The curtain of process air attenuated the extruded fibers as the fibers traveled a distance d (d=230 mm) from an exit of the plurality of spinnerets to a collection surface on an outer surface of a rotating drum having an outer diameter of 0.66 m. The drum was rotating with a linear speed of 40 m/min.[0122]

EXAMPLE 3Preparation of a Pre-Stretched Composite Material Comprising an Abrasive Meltblown Web Bonded to an Absorbent Meltblown Web

The abrasive meltblown web formed in Example 1 was bonded to the absorbent meltblown web formed in Example 2 by passing both webs through a calendering process. The abrasive meltblown web/absorbent meltblown web was then point-bonded to produce a bonded pre-stretched composite having a bond cover area of about 33% based on a total surface area of the bonded pre-stretched composite.[0123]

EXAMPLE 4Preparation of a Stretched Composite Material Comprising an Abrasive Meltblown Web Bonded to an Absorbent Meltblown Web

The pre-stretched composite material formed in Example 3 was laterally stretched in a stretching apparatus as shown in FIGS.[0124]7A-7B. The final nonwoven composite material had a final width 20% greater than the width of the bonded pre-stretched composite.

The composite material had the following properties as shown in Table[0125]1 below.

TABLE 1


Test Data for Pre-Stretched and Post-stretched Composites

	Pre-stretched	Post-stretched	%Change

Basis Weight
	110	99	−10%
(gsm)
Thickness (mm)	0.439	0.642	46%
Absorbency (%	322	402	25%
dry weight)
Drape	Good drape in	Slightly improved	+Change
	machine	machine direction
	direction, poor drape	drape, greatly
	in cross	improved cross
	direction.	direction drape
Hydro-head (psi)	>3 psi	2.6 psi	−13%

As shown in Table 1, microstretching provided the benefits of increased material thickness and bulk, increased absorbency, and also improved drape and softness.[0126]

EXAMPLE 5Preparation of a Stretched Wipe Composite Material Containing a Colorant, a Scent-Producing Agent, and a Surfactant

The stretched composite material formed in Example 4 was spray coated with a scent-producing agent, Lemon Citrus #50-3264, available from Cognis Corporation (Ambler, Pa.) and a detergent, Detergent 0240-82, also available from Cognis Corporation (Ambler, Pa.). The coated composite material was dried to form a coated, stretched wipe composite material having a desired scent and enhanced cleaning capabilities.[0127]

While the specification has been described in detail with respect to specific embodiments thereof, it will be appreciated that those skilled in the art, upon attaining an understanding of the foregoing, may readily conceive of alterations to, variations of, and equivalents to these embodiments. Accordingly, the scope of the present invention should be assessed as that of the appended claims and any equivalents thereto.[0128]