Hydroentangled web and wiping products made from same

Abstract

The present disclosure is directed to nonwoven webs particularly well suited as wiping products that can be constructed without containing synthetic polymer fibers. In one aspect, the webs are made from a blend of cellulose pulp fibers and regenerated cellulose fibers. The nonwoven webs can be formed in a foam forming process in combination with one or more hydroentangling steps.

Description

[0001] HYDROENTANGLED WEB AND WIPING PRODUCTS MADE FROM SAME

[0002] BACKGROUND

[0003] Domestic and industrial wipers are often used to absorb liquids and pick up debris. The wipers have been designed to be used in a dry state or as a premoistened wiping product for the purposes of cleaning and / or disinfecting. In the past, many attempts have been made in order to produce noncloth wiping products made from nonwoven fibers that are designed generally to be used and discarded. Such wipers should possess a good balance of properties, including good physical strength and abrasion resistance in order to withstand the tearing, stretching, and abrading forces often applied during use.

[0004] In the past, many nonwoven wipers have been constructed from wood pulp fibers in combination with synthetic fibers, such as polymer fibers. For example, in the past, wood pulp fibers, such as softwood fibers, have been hydroentangled with synthetic polymer fibers in order to produce a resilient wiping product. The synthetic polymer fibers have included polyester fibers, polypropylene fibers, and the like. Polymer synthetic fibers, however, are naturally hydrophobic and have poor absorbency. The wipers also require significant amounts of polymer, particularly fossil-based polymers, for constructing the wipers.

[0005] In view of the above, a need currently exists for nonwoven webs that can be produced with high strength properties while minimizing the amount of synthetic polymer fibers. A need also exists for a wiping product that minimizes the amount of synthetic polymer fibers while still possessing excellent cleaning properties for absorbing fluids and for wiping away sticky substances and / or food crumbs.

[0006] SUMMARY

[0007] The present disclosure is generally directed to nonwoven webs, particularly hydroentangled nonwoven webs, that contain little to no synthetic polymer fibers, particularly fibers made from fossilbased polymers. In one embodiment, for instance, the nonwoven web can be constructed so as to be completely free of polyolefin fibers, polyester fibers, or other synthetic polymer fibers. The nonwoven webs are well suited for use as wiping products and have excellent strength properties when either dry or wet.

[0008] In one embodiment, the present disclosure is directed to a wiping product comprising a base sheet containing cellulose pulp fibers in an amount from about 70% by weight to about 90% by weight, such as from about 75% by weight to about 85% by weight. The cellulose pulp fibers are blended with regenerated cellulose fibers. The regenerated cellulose fibers comprise staple fibers and optionally can comprise crimped fibers. The regenerated cellulose fibers are present in the base sheet in an amount from about 10% by weight to about 30% by weight, such as from about 15% by weight to about 25% by weight. The base sheet comprises a hydroentangled base sheet and can have a basis weight of from about 40 gsm to about 120 gsm. In one aspect, the basis weight can be from about 44 gsm to about 64 gsm. In another aspect, the basis weight can be from about 90 gsm to about 120 gsm. In one embodiment, in addition to being hydroentangled, the base sheet can also comprise a foam formed web.

[0009] The cellulose pulp fibers can comprise any suitable pulp fibers, such as wood pulp fibers. In one embodiment, the cellulose pulp fibers comprise softwood fibers, hardwood fibers, or mixtures thereof. Alternatively, the cellulose pulp fibers can comprise non-wood fibers.

[0010] The regenerated cellulose fibers can have an average fiber length of from about 5 mm to about 18 mm, such as from about 10.5 mm to about 17 mm. The regenerated cellulose fibers can have a decitex of from about 0.7 g / 10,000 m to about 2.5 g / 10,000 m, such as from about 1 g / 10,000 m to about 2 g / 10,000 m. When the fibers are crimped, the regenerated cellulose fibers can contain from about 2 crimps per cm to about 10 crimps per cm.

[0011] The wiping product of the present disclosure can comprise a single ply web that is nonlayered. In one embodiment, the cellulose pulp fibers and the regenerated cellulose fibers together comprise greater than about 90% by weight, such as greater than about 95% by weight of the total amount of fibers contained in the base sheet. As described above, the base sheet can be free of polyolefin fibers, polyester fibers, or other synthetic polymer fibers. The base sheet can generally have a bulk of from about 5 g / cc to about 25 g / cc. The base sheet can display a caliper per basis weight of greater than about 0.009 mm / gsm, such as greater than about 0.010 mm / gsm. For example, the caliper of the base sheet can be greater than about 0.57 mm, such as greater than about 0.58 mm and less than about 1 mm at a basis weight of from about 50 gsm to about 60 gsm, such as from about 52 gsm to about 56 gsm.

[0012] The wiping product of the present disclosure can comprise any suitable wiping product, such as an industrial wiper, a paper towel, or the like. The wiping product can be contained in a spirally wound roll or the wipers can be in the form of individual sheets stacked together. In one embodiment, the wiping product can be pre-saturated with a cleaning solvent.

[0013] Other features and aspects of the present disclosure are discussed in greater detail below.

[0014] BRIEF DESCRIPTION OF THE DRAWINGS

[0015] A full and enabling disclosure of the present disclosure is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

[0016] Figure 1 is a diagram of one embodiment of a process for producing base sheets in accordance with the present disclosure; Figure 2 is a diagram of an enlarged portion of the process illustrated in Figure 1 ;

[0017] Figure 3 is a graphical representation of some of the results obtained in the example below; and

[0018] Figure 4 is a graphical representation of some of the results obtained in the example below.

[0019] Repeat use of reference characters in the present specification and drawings is intended to represent the same or analogous features or elements of the present invention.

[0020] DEFINITIONS

[0021] The term "machine direction" as used herein refers to the direction of travel of the forming surface onto which fibers are deposited during formation of a nonwoven web.

[0022] The term "cross-machine direction" as used herein refers to the direction which is perpendicular to the machine direction defined above.

[0023] As used herein, the term “nonwoven web or material” refers to a web having a structure of individual fibers that are interlaid, but not in an identifiable manner as in a knitted or woven fabric. Nonwoven materials include, for example, carded webs, wet-laid webs, airlaid webs, foam-formed webs, and the like.

[0024] As used herein, the term “Pulp” generally refers to a plurality of cellulose fibers that have undergone a pulping process such that the fibers have been individualized and wherein the fibers have an elongate shape in which the apparent length exceeds the apparent width Pulp fibers can be fibrillated and can have a measurable freeness.

[0025] As used herein, the term “Caliper” is the representative thickness of a pulp sheet and is generally measured as described in the Test Methods section below. Caliper commonly has units of millimeters or microns.

[0026] As used herein, the term “Fiber Length” generally refers to the length weighted average fiber length (LWAFL) of fibers measured using an OpTest Fiber Quality Analyzer, model FQA-360 (OpTest Equipment, Inc., Hawkesbury, ON) as described in the Test Methods section below. Fiber length commonly has units of millimeters.

[0027] TEST METHODS

[0028] Fiber Properties

[0029] Fiber properties such as length, coarseness, and fraction of very long fiber, are generally determined using an OpTest Fiber Quality Analyzer-360 (OpTest Equipment, Inc., Hawkesbury, ON) in accordance with the manufacturer's instructions. Samples are generally prepared by first accurately weighing a pulp sample. The sample mass may range from about 10 to about 50 mg (bone dry) and may be taken from a handsheet or pulp sheet. The weighed sample is diluted to a known consistency (between about 2 and about 10 mg / l). An aliquot of the diluted sample (usually 200 ml) is further diluted to a final volume of 600 ml and placed in the analyzer. The sample is then analyzed according to the manufacturer’s instructions and the output of the analyzer, such as the length weighted average fiber length, and a histogram illustrating the distribution of various fiber properties for a given sample are recorded. Generally, each reported fiber property is the average of three replicates.

[0030] The output of the fiber quality analyzer is used to calculate the Very Long Fiber (VLF) fraction, which is the sum of fiber count from 6 to 14.95 mm divided by the total fiber count. Generally, the bin data output by the instrument, which provides the number of individual fibers counted within a given fiber length range, is used to determine VLF. The total number of individual fibers counted (N) and the total number of individual fibers counted having a length of 6 mm or greater (n) are determined from the bin data. The %VLF = n / N*100.

[0031] The output of the fiber quality analyzer is also used to calculate the ratio of the length weighted average fiber length (Lw) to the number average fiber length (Ln). Lw and Ln are calculated by the FQA software using the following equations: where n and L are determined by the instrument in the course of analyzing a sample. The ratio of the length weighted average fiber length (Lw) to the number average fiber length (Ln) indicates the fiber length distribution of the sample. A higher ratio is indicative of a broader fiber length distribution. A value of 1 indicates that all of the fibers in the sample have the same length.

[0032] Caliper

[0033] As used herein, the term “Caliper" is the representative thickness of a single sheet (caliper of sheet products comprising one or more plies is the thickness of a single sheet of sheet product comprising all plies) measured in accordance with TAPPI test method T402 using a ProGage 500 Thickness Tester (Thwing-Albert Instrument Company, West Berlin, N.J.). The micrometer has an anvil diameter of 2.22 inches (56.4 mm) and an anvil pressure of 132 grams per square inch (per 6.45 square centimeters) (2.0 kPa).

[0034] Basis Weight

[0035] Generally, sheets are dried and prepared for testing as set forth in TAPPI T 205 sp-02. Pulp sheets may be tested as is. The bone dry basis weight is generally measured by first cutting the samples to a specimen size of approximately 19.05 x 19.05 cm using an appropriate cutting tool. The cut sample is then placed on a balance in an oven preheated to 105 ± 2°C. Once the weight of the sample has stabilized, the weight is recorded to the nearest 0.01 gram. The bone dry basis weight equals the measured weight (W) multiplied by 27.56.

[0036] DETAILED DESCRIPTION

[0037] It is to be understood by one of ordinary skill in the art that the present discussion is a description of exemplary embodiments only and is not intended as limiting the broader aspects of the present disclosure.

[0038] In general, the present disclosure is directed to hydroentangled nonwoven webs having excellent strength properties while minimizing or eliminating the use of polymer synthetic fibers. The hydroentangled nonwoven webs or sheet materials made according to the present disclosure have all different types of uses and applications and are particularly well suited for use as wipers. The product can be used as a dry product or can be premoistened and marketed as a moist wipe.

[0039] In general, the nonwoven webs made according to the present disclosure contain cellulose pulp fibers blended with regenerated cellulose fibers. The nonwoven web can be hydroentangled and can comprise a foam formed web, as opposed to a wetlaid web or an airlaid web. In one aspect, the regenerated cellulose fibers are staple fibers and may optionally comprise crimped fibers. It was discovered that the particular fiber composition in combination with the way the nonwoven web is formed leads to many beneficial properties and advantages. In particular, nonwoven webs made according to the present disclosure have wiping properties that are just as good or better than many conventional wiping products containing synthetic polymer fibers. Nonwoven webs made according to the present disclosure, however, are sustainable and more readily biodegradable. In one aspect, the nonwoven webs made according to the present disclosure can be constructed so as to be "plastic free” meaning that the webs do not contain any polymers derived from fossilized fuels or resources.

[0040] Although the base sheets can be formed using any suitable process, such as a conventional wetlaid process, in one embodiment as described above, the hydroentangled base sheets of the present disclosure are produced according to a foam forming process. The foam forming process, for instance, in certain embodiments, is well suited to processing longer fibers. The foam forming process is also well suited to processing three-dimensional fibers, such as crimped fibers. Further, foam forming processes require less water in comparison to conventional wetlaid processes and produce base sheets that can be dried more efficiently. Thus, the foam forming process also contributes to further environmental benefits and sustainability.

[0041] As described above, base sheets made according to the present disclosure can primarily comprise cellulose pulp fibers. Suitable cellulose pulp fibers include, but are not limited to, nonwoody fibers, such as cotton, abaca, kenaf, sabai grass, flax, esparto grass, straw, jute hemp, bagasse, milkweed floss fibers, and pineapple leaf fibers; and woody or pulp fibers such as those obtained from deciduous and coniferous trees, including softwood fibers, such as Northern and / or Southern softwood kraft fibers; hardwood fibers, such as eucalyptus, maple, birch, and aspen. Pulp fibers can be prepared in high-yield or low-yield forms and can be pulped in any known method, including kraft, sulfite, high- yield pulping methods and other known pulping methods. Fibers prepared from organosolv pulping methods can also be used.

[0042] Chemically treated natural cellulosic fibers can be used such as mercerized pulps, chemically stiffened or crosslinked fibers, or sulfonated fibers. For good mechanical properties in using papermaking fibers, it can be desirable that the fibers be relatively undamaged and largely unrefined or only lightly refined. While recycled fibers can be used, virgin fibers are generally useful for their mechanical properties and lack of contaminants. In certain embodiments capable of high bulk and good compressive properties, the fibers can have a Canadian Standard Freeness of at least 200, more specifically at least 300, more specifically still at least 400, and most specifically at least 500.

[0043] Other papermaking fibers that can be used in the present disclosure include high yield fibers. High yield pulp fibers are those papermaking fibers produced by pulping processes providing a yield of about 65% or greater, more specifically about 75% or greater, and still more specifically about 75% to about 95%. Yield is the resulting amount of processed fibers expressed as a percentage of the initial wood mass. Such pulping processes include bleached chemithermomechanical pulp (BCTMP), chemithermomechanical pulp (CTMP), pressure / pressure thermomechanical pulp (PTMP), thermomechanical pulp (TMP), thermomechanical chemical pulp (TMCP), high yield sulfite pulps, and high yield Kraft pulps, all of which leave the resulting fibers with high levels of lignin. High yield fibers are well known for their stiffness in both dry and wet states relative to typical chemically pulped fibers.

[0044] In one aspect, the cellulose pulp fibers comprise wood pulp fibers, such as softwood fibers, hardwood fibers, or mixtures thereof. In an alternative embodiment, the cellulose pulp fibers present in the base sheet comprise non-wood pulp fibers. In one embodiment, for instance, all of the cellulose pulp fibers comprise non-wood pulp fibers.

[0045] The cellulose pulp fibers are present in the base sheet generally in an amount greater than 50% by weight and in an amount up to about 90% by weight, including all increments of 1% by weight therebetween. For instance, the cellulose pulp fibers can be present in the base sheet in an amount greater than about 70% by weight, such as in an amount greater than about 72% by weight, such as in an amount greater than about 75% by weight, such as in an amount greater than about 77% by weight, and in an amount less than about 88% by weight, such as in an amount less than about 85% by weight, such as in an amount less than about 83% by weight. The cellulose pulp fibers are blended with regenerated cellulose fibers. In one embodiment, for instance, all of the fibers contained in the base sheet comprise either cellulose pulp fibers or regenerated cellulose fibers.

[0046] The regenerated fibers are man-made filaments obtained by extruding or otherwise treating regenerated or modified cellulosic materials from woody or non-woody plants, as is known in the art. For example, but not by way of limitation, the regenerated fibers may include one or more of lyocell, viscose, rayon, and the like. The regenerated cellulose fibers can be produced by dissolving cellulose in a suitable solvent and then extruding the solution through a suitable fiber-making device, such as a spinneret, to produce continuous filaments. The continuous filaments are then cut to a desired length to produce staple fibers.

[0047] The regenerated cellulose fibers can be contained in the nonwoven web in the form of staple fibers. For example, the regenerated cellulose fibers can have an average fiber length of greater than about 5 mm, such as greater than about 6.5 mm, such as greater than about 8.5 mm, such as greater than about 9 mm, such as greater than about 9.5 mm, such as greater than about 10 mm, such as greater than about 10.5 mm. The average fiber length can be less than about 20 mm, such as less than about 19 mm, such as less than about 18 mm, such as less than about 17 mm, such as less than about 16 mm, such as less than about 15 mm, such as less than about 14 mm.

[0048] In some embodiments, the regenerated fibers may have a decitex in the range of about 0.7 g / 10,000 m to about 2.5 g / 10,000 m. Moreover, the decitex may be greater than about 1 g / 10,000 m, such as greater than about 1 .2 g / 10,000 m, such as greater than about 1.4 g / 10,000 m, such as greater than about 1 .5 g / 10,000 m. The decitex can be less than about 2.5 g / 10,000 m, such as less than about 2.3 g / 10,000 m, such as less than about 2 g / 10,000 m, such as less than about 1 .9 g / 10,000 m. In one suitable embodiment, the regenerated fibers are not fibrillated.

[0049] Regenerated cellulose fibers, such as lyocell fibers, are produced in a natural uncrimped state. In one aspect, however, the regenerated cellulose fibers incorporated into the base sheet of the present disclosure can optionally comprise crimped fibers. The regenerated cellulose fibers can be crimped using any suitable mechanical or chemical method. In one aspect, for instance, the regenerated cellulose fibers can be crimped with the aid of dry steam.

[0050] The crimped regenerated cellulose fibers incorporated into the base sheet can have from about 2 crimps per cm to about 10 crimps per cm. For instance, the fibers can have greater than about 2.2 crimps per cm, such as greater than about 2.5 crimps per cm, such as greater than about 2.7 crimps per cm, and less than about 8 crimps per cm, such as less than about 6 crimps per cm, such as less than about 5 crimps per cm, such as less than about 4 crimps per cm. Crimp in the regenerated cellulose fibers can be determined by taking a titer of about 200 tex from a dry tow and placing sufficient tension to pull out the crimp. Marks can be made on the sample every 10 cm. The tension can be removed and the number of crimps between the marks can be counted. The ratio of tensioned to untensioned length also provides the intensity or crimp ratio. The crimp intensity of the crimped regenerated cellulose fibers, for instance, can be greater than about 0.8, such as greater than about 1 , such as greater than about 1.1 , such as greater than about 1.2, and less than about 5.

[0051] The amount of staple fibers, such as regenerated cellulose fibers, contained in base sheets made according to the present disclosure is generally less than about 50% by weight. In one aspect, the amount of staple fibers, such as regenerated cellulose fibers, contained in base sheets made according to the present disclosure can be relatively low. For instance, base sheets can be constructed in accordance with the present disclosure that contain regenerated cellulose staple fibers in an amount of less than about 30% by weight. For instance, the base sheet can contain regenerated cellulose fibers in an amount less than about 28% by weight, such as in an amount less than about 25% by weight, such as in an amount less than about 23% by weight, such as in an amount less than about 21% by weight. The regenerated cellulose fibers can be present in the base sheet generally in an amount greater than about 10% by weight, such as in an amount greater than about 13% by weight, such as in an amount greater than about 15% by weight, such as in an amount greater than about 18% by weight.

[0052] Optionally, the staple fibers can include polymer synthetic fibers in combination with or as a substitute for the regenerated cellulose fibers. However, in one aspect, the sheet products of the present disclosure can be constructed so as not to contain any thermoplastic polymers, particularly fossil-based polymers. For example, the sheet products of the present disclosure can be free of polyolefin polymers and / or free of polyester polymers.

[0053] As described above, base sheets or nonwoven webs made according to the present disclosure can be formed using any suitable process. The process, for instance, can be a wetlaid process incorporating hydroentangling jets or can be a foam forming process incorporating hydroentangling jets. In one aspect, a foam forming process is used that is particularly well suited to accommodating longer fibers. FIGS. 1 and 2, for instance, represent one embodiment of a foam forming process that may be used to produce base sheets in accordance with the present disclosure. It should be understood, however, that the embodiment illustrated in FIGS. 1 and 2 is merely for exemplary purposes.

[0054] In one aspect, the process includes first selecting a fiber furnish containing primarily cellulose pulp fibers blended with crimped regenerated cellulose fibers. The fiber furnish is then fed to a web forming process which can be a foam forming process in which the newly formed web is also subjected to a hydroentangling step. After hydroentangling the fibers, the nonwoven web can then be fed to a drying process. The drying process can include through-air dryers, heated drums, or combinations thereof.

[0055] When the base sheet is foam formed, the fiber furnish can be combined with a foam to create a foamed suspension. The fibers, for instance, can be blended with water and a foaming agent.

[0056] The foaming agent, for instance, may comprise any suitable surfactant. In one embodiment, for instance, the foaming agent may comprise sodium lauryl sulfate, which is also known as sodium laureth sulfate or sodium lauryl ether sulfate. In one embodiment, the foaming agent is a nonionic surfactant which may comprise an alkyl polyglycoside. The foaming agent, for instance, can be a C8 alkyl polyglycoside, a C10 alkyl polyglycoside, or a mixture of C8 and C10 alkyl polyglycosides.

[0057] Other foaming agents include sodium dodecyl sulfate or ammonium lauryl sulfate. In other embodiments, the foaming agent may comprise any suitable cationic and / or amphoteric surfactant. For instance, other foaming agents include fatty acid amines, amides, amine oxides, fatty acid quaternary compounds, and the like.

[0058] The foaming agent is combined with water generally in an amount greater than about 0.1 % by weight, such as in an amount greater than about 1% by weight, such as in an amount greater than about 2% by weight, such as in an amount greater than about 3% by weight. One or more foaming agents are generally present in an amount less than about 50% by weight, such as in an amount less than about 10% by weight, such as in an amount less than about 8% by weight, such as in an amount less than about 4% by weight.

[0059] Once the foaming agent and water are combined, the mixture is blended or otherwise subjected to forces capable of forming a foam. A foam generally refers to a porous matrix, which is an aggregate of hollow cells or bubbles which may be interconnected to form channels or capillaries.

[0060] The foam density can vary depending upon the particular application and various factors including the fiber furnish used. In one embodiment, for instance, the foam density of the foam can be greater than about 200 g / L, such as greater than about 250 g / L, such as greater than about 300 g / L. The foam density is generally less than about 600 g / L, such as less than about 500 g / L, such as less than about 400 g / L, such as less than about 350 g / L. In one embodiment, for instance, a lower density foam is used having a foam density of generally less than about 350 g / L, such as less than about 340 g / L, such as less than about 330 g / L. The foam will generally have an air content of greater than about 30%, such as greater than about 40%, such as greater than about 50%, such as greater than about 60%. The air content is generally less than about 80% by volume, such as less than about 70% by volume, such as less than about 65% by volume.

[0061] In order to form the nonwoven web, the foam is combined with a selected fiber furnish in conjunction with any auxiliary agents. The foamed suspension of fibers is then pumped to a tank and from the tank is fed to a headbox. FIGS. 1 and 2, for instance, show one embodiment of a process in accordance with the present disclosure for forming the web. As shown particularly in FIG. 2, the foamed fiber suspension can be fed to a tank 12 and then fed to the headbox 110. From the headbox 110, the foamed fiber suspension is issued onto an endless traveling forming fabric 26 supported and driven by rolls 28 in order to form a web 10. As shown in FIG. 2, a forming board 14 may be positioned below the web 10 adjacent to the headbox 110. Once formed on the forming fabric 26, the foam formed web can have a consistency of less than about 50%, such as less than about 20%, such as less than about 10%, such as less than about 5%. In fact, the forming consistency can be less than about 2, such as less than about 1 .8, such as less than about 1 .5 The forming consistency is generally greater than about 0.5, such as greater than about 0.8. The forming consistency indicates the ability to produce webs according to the present disclosure while minimizing the amount of water needed during formation.

[0062] Once the wet web is formed on the forming fabric 26, the web is conveyed downstream and dewatered. For instance, the process can optionally include a plurality of vacuum devices 16, such as vacuum boxes and vacuum rolls. The vacuum boxes assist in removing moisture from the newly formed web 10.

[0063] As shown in FIG. 2, the forming fabric 26 may also be placed in communication with a steambox 18 positioned above a pair of vacuum rolls 20. The steambox 18, for instance, can increase dryness and reduce cross-directional moisture variance. The applied steam from the steambox 18 heats the moisture in the wet web 10 causing the water in the web to drain more readily, especially in conjunction with the vacuum rolls 20. From the forming fabric 26, the newly formed web 10, in the embodiment shown in FIG. 1 , is conveyed downstream, subjected to hydroentangling, and dried on a through-air dryer.

[0064] After the foam formed web has been produced, the web is subjected to one or more hydroentangling steps. In the embodiment illustrated in FIG. 2, for instance, the web 10 is subjected to two different hydroentangling steps. In particular, in FIG. 2, the web 10 is hydroentangled on a first surface during a first hydroentangling step and then hydroentangled on a second and opposite surface during a second hydroentangling step. As shown in FIG. 2, for example, the process can include a first hydroentangling device 30 and a second hydroentangling device 32. The hydroentangling that occurs at each hydroentangling station may be accomplished utilizing conventional hydroentangling equipment. The hydroentangling of the foam formed web may be carried out with any appropriate working fluid such as, for example, water. The working fluid flows through a manifold which evenly distributes the fluid through a series of individual holes or orifices. Exemplary holes or orifices, for example, can have a diameter of from about 10 microns to about 200 microns. For example, the manifold may include a strip of orifices having a diameter of about 20 microns to about 50 microns. The manifold may contain about 20 to about 40 holes per inch and can include 1 to 3 rows of holes. Many other manifold configurations and combinations may be used. In the embodiment illustrated in FIG. 2, for instance, the hydroentangling device 30 includes a plurality of injectors 34, while the hydroentangling device 32 includes a plurality of injectors 36. The injectors 34 and 36 can be part of the manifold and can be in communication with a working fluid supply. In the embodiment illustrated in FIGS. 1 and 2, the first hydroentangling device 30 includes four banks of water jets or injectors 34 and the second hydroentangling device 32 also includes four banks of waterjets or injectors 36. It should be understood, however, that each hydroentangling device can include a single bank, two banks, three banks, four banks, five banks, six banks, or more of water jets.

[0065] During the hydroentangling process, the working fluid can pass through the orifices at pressures ranging from about 10 bar to about 300 bar, such as from about 20 bar to about 250 bar. Bonds between the fibers of the nonwoven web are created through hydroentangling. Thus, hydroentangling can increase the strength, such as the dry and wet strength of the nonwoven web or base sheet. Increasing the pressure during hydroentangling can increase the strength of the web that is formed.

[0066] The fluid impacts the material or web which can be supported on a foraminous surface or wire or may be supported on a porous drum surface. In the embodiment illustrated in FIG. 2, for instance, hydroentangling occurs on a first drum 38 and a second drum 40.

[0067] When supported on a foraminous surface or wire during hydroentangling, the wire can have a mesh size of from about 40x40 to about 100x100. The wire or surface may also be a multi-ply mesh having a mesh size of from about 50x50 to about 200x200. In one aspect, only one side of the web 10 is hydroentangled.

[0068] As described above, alternatively, the web 10 can be placed directly onto the surface of the drum 38 and on the surface of the drum 40 during hydroentangling. Each drum can include a plurality of openings or vacuum passages for withdrawing excess water. These openings or vacuum passages can also create a pattern into the web 10 during the hydroentangling process. For example, a pattern can be formed into one surface of the web at the first hydroentangling station and a pattern can be formed into the second and opposite surface of the web at the second hydroentangling station. The pattern formed into each surface of the web 10 can be highly distinctive and can increase the aesthetic appeal of nonwoven materials made from the web. In addition, the pattern formed into the web can be three-dimensional including hills and valleys. This three-dimensional topography can further improve various properties of the material.

[0069] Once the foam formed web 10 is hydroentangled one or more times, the web can be dried using a non-compressive drying operation. For example, as shown in FIG. 1, the foam formed web can be dried using a through-air dryer.

[0070] Referring to FIG. 1, the foam formed and hydraulically entangled web 10 is transferred from the drum 40 to a throughdrying fabric 44 with the aid of a vacuum transfer roll 46 or a vacuum transfer shoe. If desired, the throughdrying fabric can be run at a slower speed than the web 10 to further enhance stretch. Transfer can be carried out with vacuum assistance to ensure deformation of the sheet to conform to the throughdrying fabric, thus yielding desired bulk and appearance if desired.

[0071] In the embodiment illustrated in FIG. 1 , the foam formed web 10 is transferred to a throughdrying fabric 44. Alternatively, the foam formed web can be transferred to a metal, porous sleeve that forms the circumference of the throughdryer 48.

[0072] Alternatively, the foam formed web 10 can be conveyed on the throughdrying fabric 44 over the circumference of the throughdryer 48. The throughdrying fabric can contain high and long impression knuckles. For example, the throughdrying fabric can have about from about 5 to about 300 impression knuckles per square inch which are raised at least about 0.005 inches above the plane of the fabric. During drying, the web can be further macroscopically arranged to conform to the surface of the throughdrying fabric. Flat surfaces, however, can also be used in the present disclosure.

[0073] The side of the web contacting the throughdrying fabric is typically referred to as the "fabric side" of the nonwoven web. The fabric side of the nonwoven web, as described above, may have a shape that conforms to the surface of the throughdrying fabric after the fabric is dried in the throughdryer. The opposite side of the nonwoven web, on the other hand, is typically referred to as the "air side". The air side of the web is typically smoother than the fabric side during normal throughdrying processes.

[0074] The level of vacuum used for the web transfers can be from about 3 to about 15 inches of mercury (75 to about 380 millimeters of mercury), preferably about 5 inches (125 millimeters) of mercury. The vacuum shoe or roll (negative pressure) can be supplemented or replaced by the use of positive pressure from the opposite side of the web to blow the web onto the next fabric in addition to or as a replacement for sucking it onto the next fabric with vacuum.

[0075] The web is finally dried to a consistency of about 94 percent or greater by the throughdryer 48 and thereafter transferred to a carrier fabric 50. The dried basesheet 52 is transported to the reel 54 using carrier fabric 50 and an optional carrier fabric 56. An optional pressurized turning roll 58 can be used to facilitate transfer of the web from carrier fabric 50 to fabric 56. Suitable carrier fabrics for this purpose are Albany International 84M or 94M and Asten 959 or 937, all of which are relatively smooth fabrics having a fine pattern. Although not shown, reel calendering or subsequent off-line calendering can be used to improve the smoothness and softness of the basesheet. The basis weight of webs made in accordance with the present disclosure can vary depending upon the final product. In general, the basis weight of the products may vary from about 40 gsm to about 120 gsm. The basis weight, for instance, can be greater than about 44 gsm, such as greater than about 48 gsm, such as greater than about 50 gsm, such as greater than about 52 gsm, and generally less than about 80 gsm, such as less than about 70 gsm, such as less than about 64 gsm, such as less than about 60 gsm. In one aspect, however, higher basis weight webs can be formed having a basis weight of from about 90 gsm to about 120 gsm.

[0076] The process of the present disclosure can also produce webs with good bulk characteristics. The dry bulk, for instance, can generally be greater than about 3 cc / g, such as greater than about 5 cc / g, such as greater than about 8 cc / g, and generally less than about 20 cc / g, such as less than about 15 cc / g.

[0077] The base sheet can display an enhanced caliper per basis weight of greater than about 0.009 mm / gsm, such as greater than about 0.010 mm / gsm. For example, the caliper of the base sheet can be greater than about 0.57 mm, such as greater than about 0.58 mm and less than about 1 mm at a basis weight of from about 50 gsm to about 60 gsm, such as from about 52 gsm to about 56 gsm. It is believed that the process of the present disclosure in combination with the fiber furnish produces webs with greater thickness and open structure leading to a better feel and better cleaning properties.

[0078] In one embodiment, the nonwoven material can be cut into individual sheets The wipers may have any suitable size and shape. In one embodiment, the wiper can have a width of from about 8 cm to about 100 cm, such as from about 10 cm to about 50 cm, such as from about 20 cm to about 25 cm. The length of the wiper can be from about 10 cm to about 200 cm, such as from about 20 cm to about 100 cm, such as from about 35 cm to about 45 cm. Alternatively, the nonwoven material can be spirally wound into a roll and periodically perforated to produce tear away individual sheets.

[0079] Wipers made according to the present disclosure can be distributed as dry wipers or as moist wipes. In one aspect, the wiper can be pre-moistened with a wetting solution, such as water, a solvent, a waterless hand cleanser, or any other suitable liquid. The liquid may contain antiseptics, surfactants, emollients, humectants, and so forth. Generally, each wiper contains greater than about 100 wt. %, in some embodiments from about 150 to about 1500 wt. %, and in some embodiments, from about 300 to about 1200 wt. % of the liquid based on the dry weight of the wiper.

[0080] The wipers may be packaged in a variety of forms, materials and / or containers, including, but not limited to spirally wound rolls, boxes, tubs, flexible packaging materials, and so forth. Some examples of suitable containers include rigid tubs, film pouches, etc.

[0081] The present disclosure may be better understood with reference to the following example. Example

[0082] The following example demonstrates some of the advantages and benefits of the present disclosure. It was discovered that nonwoven webs made according to the present disclosure, especially foam formed webs, provide an open structure for superior water absorption, flexibility, and consistency of performance. These advantages are based upon not only the manner in which the web is formed but also based upon the basis weight and fiber furnish to produce an overall wiping product that demonstrates great performance without containing any synthetic polymer fibers.

[0083] Foam formed base sheets were produced according to the present disclosure containing cellulose pulp fibers in combination with regenerated cellulose staple fibers. The cellulose pulp fibers used were softwood kraft fibers. The regenerated cellulose staple fibers comprised crimped TENCEL lyocell fibers available from Lenzing. The regenerated cellulose fibers had a decitex of 1 .7 g / 10,000 m and had an average fiber length of 12 mm. The nonwoven webs had a basis weight of 54 gsm and contained 80% by weight cellulose pulp fibers and 20% by weight regenerated cellulose fibers. The base sheets were made using a foam forming process including a hydroentangling step. The base sheets were hydroentangled on one side from four banks of fluid jets.

[0084] The nonwoven webs made according to the present disclosure were then subjected to two sets of comparative testing. In the first set of tests, the nonwoven webs were cut to a size of 12.6 inches x 12.5 inches and packaged in a pop-up box. The nonwoven web of the present disclosure was compared with a commercial wiper marketed under the name WYPALL X60 hydroknit wipers commercially available from Kimberly-Clark.

[0085] In a second set of tests, the nonwoven webs were packaged in a spirally wound roll that was perforated to supply sheets having a size of 16.5 inches x 15 inches. The spirally wound product made in accordance with the present disclosure was compared with a cleaning cloth marketed by Tork under product designation 510104.

[0086] Use tests were completed during each set of comparative testing. During the use test, the products were compared for the ability to wipe up water, chocolate syrup, and food crumbs. The results were illustrated in FIGS. 3 and 4. FIG. 3 illustrates the results when compared to the WYPALL product, while FIG. 4 illustrates the results of the comparison to the Tork cleaning cloth.

[0087] As shown, nonwoven webs made according to the present disclosure were preferred by the users.

[0088] As expected, the nonwoven webs made according to the present disclosure did not perform as well as the comparative samples regarding a stress / strength test due to the absence of any synthetic polymer fibers. However, the nonwoven webs displayed sufficient strength for the intended use of the product. These and other modifications and variations to the present invention may be practiced by those of ordinary skill in the art, without departing from the spirit and scope of the present invention, which is more particularly set forth in the appended claims. In addition, it should be understood that aspects of the various embodiments may be interchanged both in whole or in part. Furthermore, those of ordinary skill in the art will appreciate that the foregoing description is by way of example only and is not intended to limit the invention so further described in such appended claims.

Claims

What Is Claimed:1 . A wiping product comprising: a base sheet containing cellulose pulp fibers in an amount of from about 70% by weight to about 90% by weight, the cellulose pulp fibers being blended with regenerated cellulose fibers, the regenerated cellulose fibers comprising staple fibers, the regenerated cellulose fibers being present in the base sheet in an amount of from about 10% by weight to about 30% by weight; and wherein the base sheet has been hydroentangled and has a basis weight of from about 40 gsm to about 120 gsm and wherein the base sheet displays a caliper per basis weight of greater than about 0.009 mm / gsm.

2. A wiping product as defined in claim 1 , wherein the base sheet comprises a foam formed web.

3. A wiping product as defined in any of the preceding claims, wherein the base sheet displays a caliper per basis weight of greater than about 0.010 mm / gsm.

4. A wiping product as defined in any of the preceding claims, wherein the cellulose pulp fibers comprise wood pulp fibers.

5. A wiping product as defined in claim 4, wherein the cellulose pulp fibers comprise softwood pulp fibers.6 A wiping product as defined in claim 1 , 2 or 3, wherein the cellulose pulp fibers comprise non-wood pulp fibers.

7. A wiping product as defined in any of the preceding claims, wherein the regenerated cellulose fibers have an average fiber length of from about 5 mm to about 18 mm.

8. A wiping product as defined in any of the preceding claims, wherein the regenerated cellulose fibers have an average fiber length of from about 10.5 mm to about 17 mm.

9. A wiping product as defined in any of the preceding claims, wherein the regenerated cellulose fibers have a decitex of from about 0.7 g / 10,000 m to about 2.5 g / 10,000 m.

10. A wiping product as defined in any of the preceding claims, wherein the regenerated cellulose fibers have a decitex of from about 1 g / 10,000 m to about 2 g / 10,000 m.

11. A wiping product as defined in any of the preceding claims, wherein the regenerated cellulose fibers comprise crimped fibers.

12. A wiping product as defined in claim 11 , wherein the crimped fibers contain from about 2 crimps per cm to about 10 crimps per cm.

13. A wiping product as defined in any of the preceding claims, wherein the wiping product comprises a single ply web that is non-layered.

14. A wiping product as defined in any of the preceding claims, wherein the base sheet has a basis weight of from about 44 gsm to about 64 gsm.

15. A wiping product as defined in any of the preceding claims, wherein the base sheet has a basis weight of from about 90 gsm to about 120 gsm.

16. A wiping product as defined in any of the preceding claims, wherein the base sheet contains cellulose pulp fibers in an amount of from about 75% by weight to about 85% by weight and contains the regenerated cellulose fibers in an amount of from about 15% by weight to about 25% by weight.

17. A wiping product as defined in any of the preceding claims, wherein the cellulose pulp fibers and the regenerated cellulose fibers together comprise greater than about 90% by weight, such as greater than about 95% by weight of the total amount of fibers contained in the base sheet.

18. A wiping product as defined in any of the preceding claims, wherein the base sheet is free of polyolefin fibers and polyester fibers.

19. A wiping product as defined in any of the preceding claims, wherein the base sheet is free of synthetic polymer fibers.

20. A wiping product as defined in any of the preceding claims, wherein the base sheet has a bulk of from about 5 g / cc to about 25 g / cc.21 . A wiping product as defined in any of the preceding claims, wherein the wiping product comprises an industrial wiper.

22. A wiping product as defined in claim 21 , wherein the industrial wiper includes a plurality of individual sheets stacked together.

23. A wiping product as defined in any of the preceding claims, wherein the wiping product is pre-saturated with a cleaning solvent.

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