WO2025024625A1

WO2025024625A1 - A foam-formed flushable tissue product with an ion-triggerable binder

Info

Publication number: WO2025024625A1
Application number: PCT/US2024/039477
Authority: WO
Inventors: Robert S. MONSON; Joel M. Vanlanen; Stephen A. Marrano
Original assignee: Kimberly Clark Worldwide Inc; Kimberly Clark Corp
Current assignee: Kimberly Clark Worldwide Inc; Kimberly Clark Corp
Priority date: 2023-07-25
Filing date: 2024-07-25
Publication date: 2025-01-30
Anticipated expiration: 2026-01-25

Abstract

A method for forming a tissue product includes depositing a foamed slurry of fibers onto a forming surface in order to form a wet web and drying the wet web. Prior to drying the wet web, the wet web includes an ion-triggerable binder composition applied to the fibers.

Description

A FOAM-FORMED FLUSHABLE TISSUE PRODUCT WITH AN ION-TRIGGERABLE BINDER

BACKGROUND

Dispersible moist wipes are generally intended to be used and then flushed down a toilet. Accordingly, flushable moist wipes generally have an in-use strength sufficient to withstand a user's extraction of the wipe from a dispenser and the user's wiping activity, but then relatively quickly breakdown and disperse in household and municipal sanitization systems, such as sewer or septic systems. Some municipalities may define ''flushable” through various regulations. Flushable moist wipes must meet such regulations to allow for compatibility with home plumbing fixtures and drain lines, as well as the disposal of the product in onsite and municipal wastewater treatment systems.

To facilitate dispersibility of the moist wipcelles, an ion-sensitive binder may adhere fibers together within the wipe. A controlled concentration of salt in the wetting solution insolubilizes the binder and allows the binder to function as an adhesive for the web. When the wet wipe is discarded into a wastewater stream, the salt concentration is diluted, the binder becomes soluble, and the strength drops in order to allow allows the wipe to break apart into small pieces and, ultimately, disperse.

Conventional methods for manufacturing dispersible moist wipes include air-laying fibers onto a preformed, dried web in order to form a layered web, spraying binder onto the layered web, and then curing the binder. Conventional methods can be time and/or energy intensive. A dispersible wet wipe that is less time and/or energy intensive to produce would be useful.

SUMMARY

In general, the present disclosure is directed to forming a tissue product by foam forming a slurry of fibers onto a forming surface and then drying the wet web. An ion-triggerable binder composition is applied to the fibers prior to drying the wet web. During the drying, the ion-triggerable binder can cure in order to bond the fibers together. By applying the ion-triggerable binder composition to the fibers prior to drying the wet web, significant energy may be saved relative to conventional processes for forming dispersible moist wipes.

In one example embodiment, a method for forming a tissue product includes depositing a foamed slurry of fibers onto a forming surface in order to form a wet web and drying the wet web. Prior to drying the wet web, the wet web includes an ion-triggerable binder composition applied to the fibers.

In another example embodiment, a method for forming a tissue product includes forming a foamed slurry of fibers. The foamed slurry of fibers includes an ion-triggerable binder composition. The method also includes depositing the foamed slurry of fibers onto a forming surface in order to form a wet web and drying the wet web.

In another example embodiment, a method for forming a tissue product includes depositing a foamed slurry of fibers onto a forming surface in order to form a wet web, spraying an ion-triggerable binder composition onto the wet web, and drying the wet web.

In an example embodiment, a wipe may be formed according to any of the methods described above.

In an example embodiment, a wipe includes a foam-formed nonwoven web with fibers and a cured ion-triggerable binder composition applied to the fibers such that the fibers are coated by the cured ion-sensitive binder composition throughout a thickness of the foam-formed nonwoven web.

These and other features, aspects and advantages of the present disclosure will become better understood with reference to the following description and appended claims. The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and, together with the description, serve to explain the principles of the disclosure.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present disclosure, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended figures.

FIG. 1 is a side schematic view of a tissue product according to example aspects of the present disclosure;

FIG. 2 is a side schematic view of a tissue product according to example aspects of the present disclosure;

FIG. 3 is a top plan view of the example tissue product of FIG. 1 ;

FIG. 4 is a schematic illustration of a process for foam-forming a basesheet for a dispersible wet wipe according to example aspects of the present disclosure; and

FIG. 5 is a schematic illustration of a multilayer foam-forming process for a dispersible wet wipe according to example aspects of the present disclosure.

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.

DETAILED DESCRIPTION

The present disclosure is generally directed to forming a tissue product by foam forming a slurry of fibers onto a forming surface and then drying the wet web. Prior to drying the wet web, an ion- triggerable binder composition is applied to the fibers. For example, the binder composition may be added to the slurry of fibers prior to foam forming the slurry onto the forming surface and/or the binder composition may be sprayed on the wet (e.g., partially dewatered) web prior to drying. Thus, the binder composition is present with the fibers in the wet web prior to drying. During the drying, the binder composition can cure in order to bond the fibers together and form a basesheet. The dried basesheet may be further treated with wetting agent and folded/rolled to form a pre-moistened foam-formed tissue product. The ion-triggerable binder composition in the tissue product may facilitate break-up of the product after use.

By applying the ion-triggerable binder composition to the fibers prior to drying the wet web, significant energy may be saved relative to conventional processes for forming dispersible moist wipes. For example, relative to conventional methods of air-laying fibers onto a preformed, dried web and then spraying binder onto the layered web, applying the ion-triggerable binder composition to the fibers prior to drying the wet web may advantageously reduce formation time and/or energy for dispersible wet wipes. Moreover, a drying step for the web prior to air-laying fibers may be completely omitted.

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.

When introducing elements of the present disclosure or the preferred embodiment(s) thereof, the articles “a”, “an”, “the” and “said” are intended to mean that there are one or more of the elements. As used herein, the terms “includes” and “including” are intended to be inclusive in a manner similar to the term “comprising.” Similarly, the term “or” is generally intended to be inclusive (i.e. , “A or B” is intended to mean “A or B or both”). Approximating language, as used herein throughout the specification and claims, is applied to modify any quantitative representation that could permissibly vary without resulting in a change in the basic function to which it is related. Accordingly, a value modified by a term or terms, such as “about,” “approximately,” and “substantially,” are not to be limited to the precise value specified. In at least some instances, the approximating language may correspond to the precision of an instrument for measuring the value. For example, the approximating language may refer to being within a ten percent (10%) margin.

Definitions:

As used herein, the term “basesheet” refers to a tissue web formed by any one of the papermaking processes described herein that has not been subjected to further processing, such as embossing, calendering, treatment with a softening or wetting composition, perforating, plying, folding, or rolling into individual rolled products.

As used herein, the term “tissue product” refers to products made from basesheets and includes, bath tissues, facial tissues, paper towels, industrial wipers, foodservice wipers, napkins, medical pads, and other similar products.

As used herein, the term “ply” refers to a discrete tissue web used to form a tissue product. Individual plies may be arranged in juxtaposition to each other.

As used herein, the term “layer” refers to a plurality of strata of fibers, chemical treatments, or the like, within a ply. A “layered tissue web” generally refers to a tissue web formed from two or more layers of foamed papermaking furnish. In certain instances, the foamed papermaking furnish forming two or more of the layers include different fiber types and/or may be manufactured by different manufacturing techniques.

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.

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 become individualized and have an elongate shape in which the apparent length exceeds the apparent width. Pulp fibers can be fibrillated and can have a measurable freeness.

As used herein, the term “basis weight” generally refers to the conditioned weight per unit area of a tissue and is generally expressed as grams per square meter (gsm). While the basis weights of tissue products prepared according to the present disclosure may vary, in certain example embodiments, the products have a basis weight greater than twenty (20) gsm, such as greater than thirty (30) gsm, such as greater than about forty (40) gsm, such as from about twenty (20) to about eighty (80) gsm, such as from about thirty (30) to about sixty (60) gsm, such as from about forty-five (45) to about fifty-five (55) gsm.

As used herein the term “machine direction” or “MD” generally refers to the direction in which a tissue web or product is produced. The term “cross-machine direction" or “CD” refers to the direction perpendicular to the machine direction.

As used herein, the term “caliper” is the representative thickness of a single sheet (caliper of dispersible wipes comprising one or more plies is the thickness of a single sheet of dispersible wipe 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).

Dispersible Wipe:

Referring to FIG. 1 , an example embodiment of a dispersible wet wipe 100 is shown. The dispersible wipe 100 is a single layer that includes a plurality of fibers 112 and a binder composition 114. The binder composition 14 may be disposed between the outer surfaces 116, 118 of the fibrous substrate. In example embodiments, the binder composition 114 may be evenly or uniformly provided between the outer surfaces 116, 118 of the single-ply wipe substrate.

Referring to FIG 2, another example embodiment of a dispersible wet wipe 200 is shown. The dispersible wipe 200 is multilayer and includes layers 210, 212, 214. The middle layer 212 may be disposed between the first outer layer 210 and the second outer layer 214 in a z-direction. Each layer 210, 212, 214 includes a respective plurality of fibers 222, 223, 225 and a binder composition 224. The binder composition 224 may be disposed between the outer surfaces 226, 228 of the fibrous substrate. In example embodiments, the binder composition 224 may be evenly or uniformly provided between the outer surfaces 226, 228 of the multilayer wipe substrate. In other example embodiments, the binder composition 224 may be provided substantially in the outer layers 210, 214 of the fibrous substrate, e.g., such that the majority of the binder composition 224 is provided in the outer layers 210, 214. Providing a majority of the binder composition 224 towards the outer surfaces 226, 228 of the wipe substrate may enhance dispersibility. In some example embodiments, about seventy-five (75) percent of the binder composition 224 may be distributed within the outer layers 210, 214 of the fibrous substrate in the z-direction.

The dispersible wet wipes 100, 200 may have sufficient strength to withstand packaging and consumer use. The dispersible wet wipes 100, 200 may also disperse sufficiently quickly to be flushable without creating potential problems for household and municipal sanitation systems. Additionally, the dispersible wet wipes 100, 200 may be constructed of materials that are suitably cost- effective.

Typically, the tissue webs of the present disclosure define a basis weight of from about twenty (20) to about one hundred and twenty (120) grams per square meter (gsm), such as from about forty (40) to about one hundred (100) grams per square meter (gsm), such as from about sixty (60) to about ninety (90) gsm. In example embodiments, the wipes of the present disclosure define a basis weight from about sixty-five (65) to about eighty (80) gsm.

The wipe substrates of the wipes 100, 200 may be a nonwoven web. The nonwoven web may include the fibrous material and the binder composition. The fibrous material used to form the nonwoven web may desirably have a relatively low wet cohesive strength prior to curing the binder composition. Thus, in the case of a dispersible nonwoven web, when the fibrous substrate is bonded together by the binder composition, the nonwoven web will preferably break apart when the nonwoven web is placed in tap water, such as found in toilets and sinks. The fibers forming the fibrous material may be made from a variety of materials including natural fibers, synthetic fibers, and combinations thereof. The choice of fibers may depend upon, for example, the intended end use of the finished substrate, the fiber cost, and whether fibers will be used for a nonwoven fabric or a nonwoven web. For instance, suitable fibers may include, but are not limited to, natural fibers, such as cotton, linen, jute, hemp, hesperaloe, wool, wood pulp, etc. Similarly, suitable fibers may also include: regenerated cellulosic fibers, such as viscose rayon and Cuprammonium rayon; modified cellulosic fibers, such as cellulose acetate; or synthetic fibers, such as those derived from polypropylenes, polyethylenes, polyolefins, polyesters, polyamides, polyacrylics, etc. Regenerated cellulose fibers include rayon in all its varieties as well as other fibers derived from viscose or chemically modified cellulose, including regenerated cellulose and solvent-spun cellulose, such as Lyocell®. Among wood pulp fibers, any known papermaking fibers may be used, including softwood and hardwood fibers. Fibers, for example, may be chemically pulped or mechanically pulped, bleached or unbleached, virgin or recycled, high yield or low yield, and the like. Chemically treated natural cellulosic fibers may be used, such as mercerized pulps, chemically stiffened or crosslinked fibers, or sulfonated fibers.

Desirably, the wipe substrates may include fibers having a length weighted average fiber length less than about three millimeters (3.0 mm), such as from about one millimeter (1 .0) to about three millimeters (3.0) mm and more preferably wood pulp fibers having a length weighted average fiber length less than about three millimeters (3.0 mm). For example, in certain example embodiments, the wipe substrate may consist essentially of wood pulp fibers having a length weighted average fiber length from about one millimeter (1 .0) to about three millimeters (3.0 mm) such as, for example, a blend of hardwood and softwood kraft pulp fibers. In example embodiments, the wood pulp fibers may include northern bleached softwood kraft (NBSK) pulp.

In some example embodiments, the wipe substrates may include synthetic fibers, such as viscose, that are longer than the wood pulp fibers. For instance, the synthetic fibers may have a length weighted average fiber length less than about fifteen millimeters (15.0 mm), such as less than about ten millimeters (10.0 mm). As an example, the synthetic fibers may have a length weighted average fiber length greater than about four millimeters (4.0 mm), such as greater than about six millimeters (6.0 mm), such as greater than about eight millimeters (8.0 mm). Moreover, in certain example embodiments, the wipe substrate may include a blend of wood pulp fibers and synthetic fibers, with the synthetic fibers having a length weighted average fiber length from about three millimeter (3.0) to about eight millimeters (8.0 mm). In addition, cellulose produced by microbes and other cellulosic derivatives may be used. As used herein, the term “cellulosic” is meant to include any material having cellulose as a major constituent, and, specifically, comprising at least fifty (50) percent by weight cellulose or a cellulose derivative. Thus, the term includes cotton, typical wood pulps, non-woody cellulosic fibers, cellulose acetate, cellulose triacetate, rayon, thermomechanical wood pulp, chemical wood pulp, debonded chemical wood pulp, milkweed, or bacterial cellulose. Blends of one or more of any of the previously described fibers may also be used, if so desired.

As used herein, the term “non-wood fiber” generally refers to cellulosic fibers derived from non-woody monocotyledonous or dicotyledonous plant stems. Non-limiting examples of dicotyledonous plants that may be used to yield non-wood fiber include kenaf, jute, flax, ramie and hemp. Non-limiting examples of monocotyledonous plants that may be used to yield non-wood fiber include cereal straws (wheat, rye, barley, oat, etc.), stalks (corn, cotton, sorghum, Hesperaloe funifera, etc.), canes (bamboo, sisal, bagasse, etc.) and grasses (miscanthus. esparto, lemon, sabai, switchgrass, etc). In still other certain instances, non-wood fiber may be derived from aquatic plants such as water hyacinth, microalgae such as Spirulina, and macroalgae seaweeds such as red or brown algae.

Still further, other cellulosic fibers for making substrates herein can include synthetic cellulose fiber types formed by spinning, including rayon in all its varieties, and other fibers derived from viscose or chemically-modified cellulose such as, for example, those available under the trade names DANUFIL, LYOCELL, and TENCEL. Some chemically-modified cellulose fibers that may be employed in substrates described herein can include chemically crosslinked pulp fibers, such as CMC535 fibers produced by International Paper.

As described above, the wipe substrates include a binder composition. The binder composition may include triggerable cationic polymers or polymer compositions. For example, the binder composition may include one or more of the binders and co-binders described in U.S. Patent No. 7,157,389, which is incorporated by reference herein. The triggerable, cationic polymer composition may be an ion-triggerable cationic polymer composition.

The amount of binder composition present in the wipe substrate may desirably range from about one (1) to about fifteen (15) percent by weight based on the total weight of the wipe substrate. More desirably, the binder composition may range from about two (2) to about ten (10) percent by weight based on the total weight of the wipe substrate. Most desirably, the binder composition may range from about four (4) to about eight (8) percent by weight based on the total weight of the wipe substrate. The amount of the binder composition may result in a single or multi-ply wipe substrate that has in-use integrity, but quickly disperses when soaked in tap water. In some example embodiments, the dispersible wipe includes from about a half (0.5) gram per square meter (gsm) to about seven (7) gsm of the binder composition. In preferred example embodiments, the dispersible wipe includes from about one (1) gsm to about six (6) gsm, such as from about one and two-tenths (1 .2) to about five (5) gsm. In other example embodiments, the dispersible wipe includes about one and four-tenths (1 .4) gsm, about two and eight-tenths (2.8) gsm, about four and two-tenths (4.2) gsm, or about five and six-tenths (5.6) gsm of the binder composition.

In some example embodiments, the dispersible wipe may have a machine direction tensile strength ranging from at least about 1000 to about 3800 gf/3in. More desirably, the wet wipe may have a machine direction tensile strength ranging from at least about 1500 to about 3000 gf/3in. Even more desirably, the wet wipe may have a machine direction tensile strength ranging from at least about 1700 to about 2800 gf/3in.

The dispersibility time of wipes made according to the present disclosure can be related to the wet geometric mean tensile strength. For instance, in one aspect, the dispersibility time in seconds can be less than the following relationship:

1 .3 x the wet GMT.

For example, the dispersibility time can be less than about one thousand (1 ,000) seconds, such as less than about eight hundred (800) seconds, such as less than about six hundred (600) seconds, such as less than about four hundred (400) seconds, such as less than about three hundred and fifty (350) seconds, such as less than about three hundred (300) seconds, such as less than about two hundred and fifty (250) seconds, such as less than about two hundred (200) seconds, such as less than about one hundred and eighty (180) seconds, such as less than about one hundred and fifty (150) seconds. The dispersibility time is generally greater than about five (5) seconds, such as greater than about thirty (30) seconds.

In example embodiments, the dispersible wipe includes triggerable cationic polymer(s) or polymer compositions. The triggerable, cationic polymer composition may be an ion-sensitive or triggerable cationic polymer composition. In order to be an effective ion-triggerable cationic polymer or cationic polymer formulation suitable for use in flushable or water-dispersible personal care products, the formulations should desirably be (1) functional; i.e., maintain wet strength under controlled conditions and dissolve or disperse in a reasonable period of time in soft or hard water, such as found in toilets and sinks around the world; (2) safe (not toxic); and (3) relatively economical. In addition to the foregoing factors, the ion-triggerable formulations when used as a binder composition for a nonwoven substrate, such as a wet wipe, desirably should be (4) processable on a commercial basis; i.e., may be applied relatively quickly on a large scale basis, such as by spraying (which thereby requires that the binder composition have a relatively low viscosity at high shear); (5) provide acceptable levels of sheet or substrate wettability; (6) provide reduced levels of sheet stiffness; and (7) reduced tackiness. The wetting composition with which the wet wipes of the present disclosure are treated can provide some of the foregoing advantages, and, in addition, can provide one or more of (8) improved skin care, such as reduced skin irritation or other benefits, (9) improved tactile properties, and (10) promote good cleaning by providing a balance in use between friction and lubricity on the skin (skin glide). The ion-triggerable cationic polymers and polymer formulations of the present disclosure and articles made therewith, especially wet wipes including particular wetting compositions set forth below, can meet many or all of the above criteria.

The ion triggerable cationic polymers of the present disclosure may be the polymerization product of a vinyl-functional cationic monomer, and one or more hydrophobic vinyl monomers with alkyl side chain sizes of up to 4 carbons long. In a preferred example embodiment, the ion triggerable cationic polymers are the polymerization product of a vinyl-functional cationic monomer, and one or more hydrophobic vinyl monomers with alkyl side chain sizes of up to 4 carbons long incorporated in a random manner. Additionally, a minor amount of another vinyl monomer with linear or branched alkyl groups 4 carbons or longer, alkyl hydroxy, polyoxyalkylene, or other functional groups may be employed. The generic structure for the ion triggerable cationic polymers is shown below:

wherein x=1 to about 15 mole percent; y=about 60 to about 99 mole percent; and z=0 to about 30 mole percent; Q is selected from C1-C4 alkyl ammonium, quaternary C1-C4 alkyl ammonium and benzyl ammonium; Z is selected from —0—, —COO—, — OOC— , — CONH— , and — NHCO— ; R1 , R2, R3 are independently selected from hydrogen and methyl; R4 is selected from methyl and ethyl; and R5 is selected from hydrogen, methyl, ethyl, butyl, ethylhexyl, decyl, dodecyl, hydroxyethyl, hydroxy propyl, polyoxyethylene, and polyoxypropylene. Vinyl-functional cationic monomers of the present invention desirably include, but are not limited to, [2-(acryloxy)ethyl] trimethyl ammonium chloride (ADAMQUAT); [2-(methacryloxy)ethyl) trimethyl ammonium chloride (MADQUAT); (3-acrylamidopropyl) trimethyl ammonium chloride; N,N-diallyldimethyl ammonium chloride; [2-(acryloxy) ethyl] dimethylbenzyl ammonium chloride; (2-(methacryloxy) ethyl] dimethylbenzyl ammonium chloride; [2-(acryloxy)ethyl] dimethyl ammonium chloride; [2-(methacryloxy)ethyl] dimethyl ammonium chloride. Precursor monomers, such as vinylpyridine, dimethylaminoethyl acrylate, and dimethylaminoethyl methacrylate, which can be polymerized and quaternized through post-polymerization reactions are also possible. Monomers or quaternization reagents which provide different counter-ions, such as bromide, iodide, or methyl sulfate are also useful. Other vinyl-functional cationic monomers which may be copolymerized with a hydrophobic vinyl monomer are also useful.

In some example embodiments of the present disclosure, the vinyl-functional cationic monomer is selected from [2-(acryloxy)ethyl]dimethyl ammonium chloride, [2-(acryloxy)ethyl]dimethyl ammonium bromide, [2-(acryloxy)ethyl]dimethyl ammonium iodide, and [2-(acryloxy)ethyl]dimethyl ammonium methyl sulfate. In some example embodiments of the present disclosure, the vinylfunctional cationic monomer is selected from [2-(methacryloxy)ethyl]dimethyl ammonium chloride, [2- (methacryloxy)ethyl]dimethyl ammonium bromide, [2-(methacryloxy)ethyl]dimethyl ammonium iodide, and [2-(methacryloxy)ethyl]dimethyl ammonium methyl sulfate. In some example embodiments of the present disclosure, the vinyl-functional cationic monomer is selected from [2-(acryloxy)ethyl]trimethyl ammonium chloride, [2-(acryloxy)ethyl]trimethyl ammonium bromide, [2-(acryloxy)ethyl]trimethyl ammonium iodide, and [2-(acryloxy)ethyl]trimethyl ammonium methyl sulfate. In some example embodiments of the present disclosure, the vinyl-functional cationic monomer is selected from [2- (methacryloxy)ethyl]trimethyl ammonium chloride, [2-(methacryloxy)ethyl]trimethyl ammonium bromide, [2-(methacryloxy)ethyl]trimethyl ammonium iodide, and [2-(methacryloxy)ethyl]trimethyl ammonium methyl sulfate. In some example embodiments of the present disclosure, the vinylfunctional cationic monomer is selected from (3-acrylamidopropyl)trimethyl ammonium chloride, (3- acrylamidopropyl)trimethyl ammonium bromide, (3-acrylamidopropyl)trimethyl ammonium iodide, and (3-acrylamidopropyl)trimethyl ammonium methyl sulfate. In some example embodiments of the present disclosure, the vinyl-functional cationic monomer is selected from N,N-diallyldimethyl ammonium chloride, N , N-diallyldimethyl ammonium bromide, N , N-diallyldimethyl ammonium iodide, and N,N- diallyldimethyl ammonium methyl sulfate. In some example embodiments of the present disclosure, the vinyl-functional cationic monomer is selected from [2-(acryloxy)ethyl]dimethylbenzyl ammonium chloride, [2-(acryloxy)ethyl]dimethylbenzyl ammonium bromide, [2-(acryloxy)ethyl]dimethylbenzyl ammonium iodide, and [2-(acryloxy)ethyl]dimethylbenzyl ammonium methyl sulfate. In some example embodiments of the present disclosure, the vinyl-functional cationic monomer is selected from [2- (methacryloxy)ethyl]dimethylbenzyl ammonium chloride, [2-(methacryloxy)ethyl]dimethylbenzyl ammonium bromide, [2-(methacryloxy)ethyl]dimethylbenzyl ammonium iodide, and [2- (methacryloxy)ethyl]dimethylbenzyl ammonium methyl sulfate.

Desirable hydrophobic monomers for use in the ion-triggerable cationic polymers include, but are not limited to, branched or linear C1-C18 alkyl vinyl ethers, vinyl esters, acrylamides, acrylates, and other monomers that can be copolymerized with the cationic monomer. As used herein, the monomer methyl acrylate is considered to be a hydrophobic monomer. Methyl acrylate has a solubility of 6 g/100 ml in water at 20° C.

In an example embodiment, the binder is the polymerization product of a cationic acrylate or methacrylate and one or more alkyl acrylates or methacrylates having the generic structure:

wherein x=1 to about 15 mole percent; y=about 60 to about 99 mole percent; and z=0 to about 30 mole percent; R4 is selected from methyl and ethyl; R5 is selected from hydrogen, methyl, ethyl, butyl, ethylhexyl, decyl, dodecyl, hydroxyethyl, hydroxypropyl, polyoxyethylene, and polyoxypropylene.

In an example embodiment of the present invention, the ion triggerable polymer has the structure:

wherein x=1 to about 15 mole percent; y=about 85 to about 99 mole percent and R4 is C1-C4 alkyl In a most desirable embodiment, when R4 is methyl, x=3 to about 6 mole percent; y=about 94 to about 97 mole percent.

The ion triggerable cationic polymers may have an average molecular weight that varies depending on the ultimate use of the polymer. The ion triggerable cationic polymers may have a weight average molecular weight ranging from about 10,000 to about 5,000,000 grams per mol. More specifically, the ion triggerable cationic polymers may have a weight average molecular weight ranging from about 25,000 to about 2,000,000 grams per mol., or, more specifically still, from about 200,000 to about 1 ,000,000 grams per mol.

In the polymerization methods of the present disclosure, any free radical polymerization initiator may be used. Selection of a particular initiator may depend on a number of factors including, but not limited to, the polymerization temperature, the solvent, and the monomers used. Suitable polymerization initiators for use in the present disclosure include, but are not limited to, 2,2'- azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'- azobis(2-amidinopropane)dihydrochloride, 2,2'-azobis(N,N'-dimethylene isobutylamidine), potassium persulfate, ammonium persulfate, and aqueous hydrogen peroxide. The amount of polymerization initiator may desirably range from about 0.01 to 5 weight percent based on the total weight of monomer present.

The polymerization temperature may vary depending on the polymerization solvent, monomers, and initiator used, but in general, ranges from about 20° C to about 90° C. Polymerization time generally ranges from about 2 to about 8 hours.

In order to be effective as a binder material in flushable products throughout the United States, the ion-triggerable cationic polymer formulations of the present disclosure remain stable and maintain their integrity while dry or in relatively high concentrations of monovalent and/or divalent ions, but become soluble in water containing up to about two hundred parts per million (200 ppm) or more divalent ions, especially calcium and magnesium. Desirably, the ion-triggerable cationic polymer formulations of the present disclosure are insoluble in a salt solution containing at least about three- tenths (0.3) weight percent of one or more inorganic and/or organic salts containing monovalent and/or divalent ions. More desirably, the ion-triggerable cationic polymer formulations of the present disclosure are insoluble in a salt solution containing from about three-tenths (0.3) to about ten (10) percent by weight of one or more inorganic and/or organic salts containing monovalent and/or divalent ions. Even more desirably, the ion-triggerable cationic polymer formulations of the present disclosure are insoluble in salt solutions containing from about a half (0.5) to about five (5) percent by weight of one or more inorganic and/or organic salts containing monovalent and/or divalent ions. Especially desirably, the ion-triggerable cationic polymer formulations of the present disclosure are insoluble in salt solutions containing from about one (1 .0) to about four (4.0) percent by weight of one or more inorganic and/or organic salts containing monovalent and/or divalent ions. Suitable monovalent ions include, but are not limited to, Na⁺ ions, K+ ions, Li⁺ ions, NH⁴⁺ ions, low molecular weight quaternary ammonium compounds (e.g., those having fewer than 5 carbons on any side group), and a combination thereof. Suitable multivalent ions include, but are not limited to, Zn²⁺, Ca²⁺ and Mg²⁺. The monovalent and divalent ions can be derived from organic and inorganic salts including, but not limited to, NaCI, NaBr, KCI, NH₄CI, Na₂SO4, ZnCI₂, CaCI₂, MgCI₂, MgSO₄, NaNO₃, NaSC CHs, and combinations thereof. Typically, alkali metal halides are most desirable because of cost, purity, low toxicity, and availability. A particularly desirable salt is NaCI.

The ion triggerable cationic polymers may function as adhesives for tissue, wetlaid pulp, and other nonwoven webs and provide sufficient in-use strength (typically >300 g/in.) in salt solutions, especially sodium chloride. The nonwoven webs may also dispersible in tap water (including hard water up to 200 ppm as metal ion), typically losing most of their wet strength (<30-75 g/in.) in 24 hours, or less.

To ensure polymer formulation dispersibility across the country (and throughout the whole world), the ion-triggerable cationic polymer formulations of the present disclosure are desirably soluble in water containing up to about 50 ppm Ca²⁺ and/or Mg²⁺ ions. More desirably, the ion-triggerable cationic polymer formulations of the present disclosure are soluble in water containing up to about 100 ppm Ca²⁺ and/or Mg²⁺ ions. Even more desirably, the ion-triggerable cationic polymer formulations of the present disclosure are soluble in water containing up to about 150 ppm Ca²⁺ and/or Mg²⁺ ions. Even more desirably, the ion-triggerable cationic polymer formulations of the present disclosure are soluble in water containing up to about 200 ppm Ca²⁺ and/or Mg²⁺ ions.

The cationic polymer formulations of the present disclosure are formed from a single triggerable cationic polymer or a combination of two or more different polymers, wherein at least one polymer is a triggerable polymer. The second polymer may be a co-binder polymer. A co-binder polymer is of a type and in an amount such that when combined with the triggerable cationic polymer, the co-binder polymer desirably is largely dispersed in the triggerable cationic polymer; i.e., the triggerable cationic polymer is desirably the continuous phase and the co-binder polymer is desirably the discontinuous phase. Desirably, the co-binder polymer can also meet several additional criteria. For example, the co-binder polymer can have a glass transition temperature; i.e., T_g, that is lower than the glass transition temperature of the ion-triggerable cationic polymer. Furthermore or alternatively, the co-binder polymer can be insoluble in water, or can reduce the shear viscosity of the ion- triggerable cationic polymer. The co-binder can be present at a level relative to the solids mass of the triggerable polymer of about forty-five (45) percent or less, specifically about thirty (30) percent or less, more specifically about twenty (20) percent or less, more specifically still about fifteen (15) percent or less, and most specifically about ten (10) percent or less, with exemplary ranges of from about one (1) to about forty-five (45) percent or from about twenty-five (25) to about thirty-five (35) percent, as well as from about one (1) to about twenty (20) percent or from about five (5) to about twenty-five (25) percent. The amount of co-binder present should be low enough, for co-binders with the potential to form water insoluble bonds or films, that the co-binder remains a discontinuous phase unable to create enough crosslinked, or insoluble bonds, to jeopardize the dispersibility of the treated substrate.

The co-binder polymer of the present disclosure can have an average molecular weight, which varies depending on the ultimate use of the polymer. Desirably, the co-binder polymer has a weight average molecular weight ranging from about 500,000 to about 200,000,000 grams per mol. More desirably, the co-binder polymer has a weight average molecular weight ranging from about 500,000 to about 100,000,000 grams per mol.

The co-binder polymer can be in the form of an emulsion latex. The surfactant system used in such a latex emulsion should be such that it does not substantially interfere with the dispersibility of the ion-triggerable cationic polymer. Therefore, weakly anionic, nonionic, or cationic latexes may be useful for the present disclosure. In one embodiment, the ion-triggerable cationic polymer formulations of the present disclosure comprises about fifty-five (55) to about ninety-five (95) weight percent ion- triggerable cationic polymer and about five (5) to about forty-five (45) weight percent poly(ethylene- vinyl acetate). More desirably, the ion-triggerable cationic polymer formulations of the present disclosure comprises about seventy-five (75) weight percent ion-triggerable cationic polymer and about twenty-five (25) weight percent poly(ethylene-vinyl acetate). A particularly preferred non-crosslinking poly(ethylene-vinyl acetate) is Dur-O-Set® RB available from National Starch and Chemical Co., Bridgewater, N.J.

When a latex co-binder, or any potentially crosslinkable co-binder, is used the latex should be prevented from forming substantial water-insoluble bonds that bind the fibrous substrate together and interfere with the dispersibility of the article. Thus, the latex can be free of crosslinking agents, such as N-methylol-acrylamide (N A), or free of catalyst for the crosslinker, or both. Alternatively, an inhibitor can be added that interferes with the crosslinker or with the catalyst such that crosslinking is impaired even when the article is heated to normal crosslinking temperatures. Such inhibitors can include free radical scavengers, methyl hydroquinone, t-butylcatechol, pH control agents such as potassium hydroxide, and the like. For some latex crosslinkers, such as N-methylol-acrylamide (NMA), for example, elevated pH such as a pH of 8 or higher can interfere with crosslinking at normal crosslinking temperatures (e.g . , about 130° C. or higher). Also alternatively, an article including a latex co-binder can be maintained at temperatures below the temperature range at which crosslinking takes place, such that the presence of a crosslinker does not lead to crosslinking, or such that the degree of crosslinking remains sufficiently low that the dispersibility of the article is not jeopardized. Also alternatively, the amount of crosslinkable latex can be kept below a threshold level such that even with crosslinking, the article remains dispersible. For example, a small quantity of crosslinkable latex dispersed as discrete particles in an ion-sensitive binder can permit dispersibility even when fully crosslinked. For the later embodiment, the amount of latex can be below about twenty (20) weight percent, and, more specifically, below about fifteen (15) weight percent relative to the ion-sensitive binder.

Latex compounds, whether crosslinkable or not, need not be the co-binder. SEM micrography of successful ion-sensitive binder films with useful non-crosslinking latex emulsions dispersed therein has shown that the latex co-binder particles can remain as discrete entities in the ion-sensitive binder, possibly serving in part as filler material. It is believed that other materials could serve a similar role, including a dispersed mineral or particulate filler in the triggerable binder, optionally comprising added surfactants/dispersants. For example, in one envisioned embodiment, free flowing Ganzpearl™ PS-8F particles from Presperse, Inc. (Piscataway, N.J.), a styrene/divinylbenzene copolymer with about 0.4 micron particles, can be dispersed in a triggerable binder at a level of about 2 to 10 weight percent to modify the mechanical, tactile, and optical properties of the triggerable binder. Other filler-like approaches may include microparticles, microspheres, or microbeads of metal, glass, carbon, mineral, quartz, and/or plastic, such as acrylic or phenolic, and hollow particles having inert gaseous atmospheres sealed within their interiors. Examples include EXPANCEL™ phenolic microspheres, which expand substantially when heated, or the acrylic microspheres known as PM™ 6545. Foaming agents, including CO2 dissolved in the triggerable binder, could also provide helpful discontinuities as gas bubbles in the matrix of a triggerable binder, allowing the dispersed gas phase in the triggerable binder to serve as the co-binder. In general, any compatible material that is not miscible with the binder, especially one with adhesive or binding properties of its own, can be used as the co-binder, if it is not provided in a state that imparts substantial covalent bonds joining fibers in a way that interferes with the water-dispersibility of the product. However, those materials that also provide additional benefits, such as reduced spray viscosity, can be especially preferred. Adhesive co-binders, such as latex that do not contain crosslinkers or contain reduced amounts of crosslinkers, have been found to be especially helpful in providing good results over a wide range of processing conditions, including drying at elevated temperatures.

The co-binder polymer can include surface active compounds that improve the wettability of the substrate after application of the binder mixture. Wettability of a dry substrate that has been treated with a triggerable polymer formulation can be a problem in some example embodiments, because the hydrophobic portions of the triggerable polymer formulation can become selectively oriented toward the air phase during drying, creating a hydrophobic surface that can be difficult to wet when the wetting composition is later applied unless surfactants are added to the wetting composition. Surfactants, or other surface active ingredients, in co-binder polymers can improve the wettability of the dried substrate that has been treated with a triggerable polymer formulation. Surfactants in the co-binder polymer should not significantly interfere with the triggerable polymer formulation. Thus, the binder should maintain good integrity and tactile properties in the pre-moistened wipes with the surfactant present.

In one example embodiment, an effective co-binder polymer replaces a portion of the ion- triggerable cationic polymer formulation and permits a given strength level to be achieved in a premoistened wipe with at least one of lower stiffness, better tactile properties (e.g., lubricity or smoothness), or reduced cost, relative to an otherwise identical pre-moistened wipe lacking the cobinder polymer and comprising the ion-triggerable cationic polymer formulation at a level sufficient to achieve the given tensile strength.

In addition to the wipe substrate, wet wipes may also contain a wetting composition. The wetting composition can be any liquid, which can be absorbed into the wet wipe basesheet and may include any suitable components, that provide the desired wiping properties. For example, the components may include water, emollients, surfactants, fragrances, preservatives, organic or inorganic acids, chelating agents, pH buffers, or combinations thereof, as are well known to those skilled in the art. Further, the liquid may also contain lotions, medicaments, and/or antimicrobials. The wetting compositions may contain any of the components described in U.S. Patent Publication No. 2011/0293931, which is incorporated by reference herein.

In the case of a dispersible wipe, the wetting composition for use in combination with the nonwoven materials may desirably comprise an aqueous composition containing the insolubilizing agent that maintains the coherency of the binder composition and thus the in-use strength of the wet wipe until the insolubilizing agent is diluted with tap water. Thus, the wetting composition may contribute to the triggerable property of the triggerable polymer and concomitantly the binder composition.

The insolubilizing agent in the wetting composition can be a salt, such as those previously disclosed for use with the ion-sensitive polymer, a blend of salts having both monovalent and multivalent ions, or any other compound, which provides in-use and storage strength to the binder composition and may be diluted in water to permit dispersion of the wet wipe as the binder composition transitions to a weaker state. The wetting composition may desirably contain more than about 0.3 weight percent of an insolubilizing agent based on the total weight of the wetting composition. The wetting composition may desirably contain from about 0.3 to about 3.5 weight percent of an insolubilizing agent based on the total weight of the wetting composition. More desirably, the wetting composition may contain from about 0.5 to about 3.5 weight percent of an insolubilizing agent based on the total weight of the wetting composition. More desirably, the wetting composition may contain from about 1 to about 3.5 weight percent of an insolubilizing agent based on the total weight of the wetting composition. Even more desirably, the wetting composition may contain from about 1 to about 2 weight percent of an insolubilizing agent based on the total weight of the wetting composition.

The wetting composition may desirably be compatible with the triggerable polymer, the cobinder polymer, and any other components of the binder composition. In addition, the wetting composition desirably contributes to the ability of the wet wipes to maintain coherency during use, storage and/or dispensing, while still providing dispersibility in tap water.

In one example, the wetting compositions may contain water. The wetting compositions can suitably contain water in an amount of from about 0.1 to about 99.9 percent by weight of the composition, more typically from about 40 to about 99 percent by weight of the composition, and more preferably from about 60 to about 99.9 percent by weight of the composition. For instance, where the composition is used in connection with a wet wipe, the composition can suitably contain water in an amount of from about 75 to about 99.9 percent by weight of the composition

The wetting compositions may further contain additional agents that impart a beneficial effect on skin or hair and/or further act to improve the aesthetic feel of the compositions and wipes described herein. Examples of suitable skin benefit agents include emollients, sterols or sterol derivatives, natural and synthetic fats or oils, viscosity enhancers, rheology modifiers, polyols, surfactants, alcohols, esters, silicones, clays, starch, cellulose, particulates, moisturizers, film formers, slip modifiers, surface modifiers, skin protectants, humectants, sunscreens, and the like.

Formation System and Method:

Desirably, the dispersible wipes may be constructed from tissue webs. Basesheets suitable for this purpose can be made using any process that produces a high density, resilient tissue structure. Such processes include foam-forming processes. FIGS. 4 and 5, for instance, represent example embodiments of foam forming processes that may be used to produce base sheets in accordance with the present disclosure. It should be understood, however, that the example embodiments illustrated in FIGS. 4 and 5 are merely for exemplary purposes.

In one example aspect, the process includes first selecting a fiber furnish, such as a fiber furnish containing primarily wood pulp fibers, such as NBSK pulp fibers. The fiber furnish may then be fed to a foam forming process. After formation, the nonwoven web may then be fed to a drying process. The drying process may include through-air dryers, heated drums, or combinations thereof.

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

The foaming agent, for instance, may include any suitable surfactant. In an example embodiment, the foaming agent may include sodium lauryl sulfate, which is also known as sodium laureth sulfate or sodium lauryl ether sulfate. In one example embodiment, the foaming agent may be a nonionic surfactant, which may include an alkyl polyglycoside. The foaming agent, for instance, may be a C8 alkyl polyglycoside, a C10 alkyl polyglycoside, or a mixture of C8 and C10 alkyl polyglycosides. Other foaming agents include sodium dodecyl sulfate or ammonium lauryl sulfate. In other example embodiments, the foaming agent may include 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.

The foaming agent may be combined with water generally in an amount greater than about one-tenth percent (0.1%) by weight, such as in an amount greater than about one percent (1%) by weight, such as in an amount greater than about two percent (2%) by weight, such as in an amount greater than about three percent (3%) by weight. One or more foaming agents are generally present in an amount less than about fifty percent (50%) by weight, such as in an amount less than about ten percent (10%) by weight, such as in an amount less than about eight percent (8%) by weight, such as in an amount less than about four percent (4%) by weight.

Once the foaming agent and water are combined, the mixture may be 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.

The foam density can vary depending upon the particular application and various factors, including the fiber furnish used. In an example embodiment, the foam density of the foam may be greater than about two hundred grams per liter (200 g/L), such as greater than about two hundred and fifty grams per liter (250 g/L), such as greater than about three hundred grams per liter (300 g/L). The foam density may be generally less than about six hundred grams per liter (600 g/L), such as less than about five hundred grams per liter (500 g/L), such as less than about four hundred grams per liter (400 g/L), such as less than about three hundred and fifty grams per liter (350 g/L). In one example embodiment, for instance, a lower density foam may be used having a foam density of generally less than about three hundred and fifty grams per liter (350 g/L), such as less than about three hundred and forty grams per liter (340 g/L), such as less than about three hundred and thirty grams per liter (330 g/L). The foam may generally have an air content of greater than about thirty percent (30%), such as greater than about forty percent (40%), such as greater than about fifty percent (50%), such as greater than about sixty percent (60%). The air content is generally less than about eighty percent (80%) by volume, such as less than about seventy percent (70%) by volume, such as less than about sixty-five percent (65%) by volume.

In order to form the nonwoven web, the foam may be combined with a selected fiber furnish in conjunction with any auxiliary agents. The foamed suspension of fibers may then be pumped to a tank and from the tank be fed to a headbox. FIGS. 4 and 5 show example embodiments of processes in accordance with the present disclosure for forming the web. As shown particularly in FIG. 4, the foamed fiber suspension may be fed to a tank 12 and then fed to the headbox 11 . From the headbox 11 , 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. 4, a forming board 14 may be positioned below the web 10 adjacent to the headbox 11 .

Once formed on the forming fabric 26, the foam formed web may have a consistency of less than about fifty percent (50%), such as less than about twenty percent (20%), such as less than about ten percent (10%), such as less than about five percent (5%). In fact, the forming consistency may be less than about two percent (2%), such as less than about one and eight-tenths percent (1 .8%), such as less than about one and a half percent (1 .5%). The forming consistency may be generally greater than about a half percent (0.5%), such as greater than about eight-tenths percent (0.8%). The forming consistency may indicate the ability to produce webs according to the present disclosure while minimizing the amount of water needed during formation.

Once the wet web is formed on the forming fabric 26, the web is conveyed downstream and dewatered. For instance, the process may 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.

As shown in FIG. 4, 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, may 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 wet web 10, in the example embodiment shown in FIG. 4, is conveyed downstream and dried during a non-compressive drying operation. For example, the foam formed web may be dried using a through-air dryer.

As may be seen from the above, once the foamed slurry of fibers is formed into a tissue web, the tissue web may be processed using various techniques and methods. For example, referring to FIG. 4, the wet web may be further processed to provide throughdried tissue sheets. For simplicity, the various tensioning rolls schematically used to define the several fabric runs are shown, but not numbered. It will be appreciated that variations from the apparatus and method illustrated in FIG. 4 can be made without departing from the general process.

As shown in FIG. 4, the wet web may be transferred from the forming fabric 26 to a transfer fabric 40. In an example embodiment, the transfer fabric 40 may be traveling at a slower speed than the forming fabric 26 in order to impart increased stretch into the web 10. This is commonly referred to as a “rush" transfer. The transfer fabric 40 may have a void volume that is equal to or less than that of the forming fabric 26. The relative speed difference between the two fabrics 26, 40 may be from zero to sixty (0-60) percent, more specifically from about fifteen to forty-five (15-45) percent. Transfer may be carried out with the assistance of a vacuum shoe 42 such that the forming fabric 26 and the transfer fabric 40 may simultaneously converge and diverge at the leading edge of the vacuum slot.

The foam formed web 10 is transferred from the transfer fabric 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 44 may be run at a slower speed than the transfer fabric 40 to further enhance stretch. Transfer may be carried out with vacuum assistance to ensure deformation of the sheet to conform to the throughdrying fabric 44, thus yielding desired bulk and appearance if desired. Suitable throughdrying fabrics are described in U.S. Pat. No. 5,429,686 issued to Kai F. Chiu et al. and U.S. Pat. No. 5,672,248 to Wendt, et al. which are incorporated by reference.

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.

The level of vacuum used for the web transfers can be from about seventy-five (75) to about three hundred and eighty (380) millimeters of mercury, preferably about one hundred and twenty-five (125) millimeters of mercury. The vacuum shoe or roll (negative pressure) may 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 the web onto the next fabric with vacuum.

While supported by the through-air drying fabric, the web is dried to a consistency of about ninety-four (94) percent or greater by the through-air dryer 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. In one example embodiment, the reel 54 shown in FIG. 4 may run at a speed slower than the fabric 56 in a rush transfer process for building bulk into the paper web 52. For instance, the relative speed difference between the reel 54 and the fabric 56 may be from about five (5) to about twenty-five (25) percent and, particularly from about twelve (12) to about twenty (20) percent, such as about eighteen (18) percent. Rush transfer at the reel 54 may occur either alone or in conjunction with other rush transfer processes upstream. Although not shown, reel calendering or subsequent off-line calendering can be used to improve the smoothness and softness of the basesheet 52.

In one example embodiment, the resulting foam formed web 52 is a textured web, which has been dried in a three-dimensional state. The texture in the web can be created due to the manner in which the web is dried using the through-dryer 48 or can be a result of other processes. For example, the web 52 may be dried while still including a pattern formed into the web.

In general, any process capable of forming a paper web can also be utilized in the present disclosure. For example, a papermaking process of the present disclosure can utilize creping, double creping, embossing, creped through-air drying, uncreped through-air drying, coform, hydroentangling, as well as other steps known in the art.

After forming the basesheet 52, a wetting composition may be applied to the substrate to generate a wet wipe, the wet wipe may be placed in roll form or in a stack, and the wet wipe may be packaged. In example embodiments, a roll of the dried basesheet 52 from the reel 54 may be transferred to a fan folding apparatus that treats the basesheet 52 with the wetting composition and fan folds the basesheet 52 to form the wet wipes. The finished wet wipes may be individually packaged, desirably in a folded condition, in a moisture proof envelope or packaged in containers holding any desired number of sheets in a water-tight package with a wetting composition applied to the wipe. Some example processes which can be used to manufacture folded wet wipes are described in U.S. Pat. Nos. 5,540,332 and 6,905,748, which are incorporated by reference herein. The finished wipes may also be packaged as a roll of separable sheets in a moisture-proof container holding any desired number of sheets on the roll with a wetting composition applied to the wipes. The roll can be coreless and either hollow or solid. Coreless rolls, including rolls with a hollow center or without a solid center, can be produced with known coreless roll winders, including those of SRP Industry, Inc. of San Jose, Calif.; Shimizu Manufacturing of Japan, and the devices disclosed in U.S. Pat. No. 4,667,890. U.S. Pat. No. 6,651 ,924 also provides examples of a process for producing coreless rolls of wet wipes.

In example embodiments, a basesheet may be formed as a multi-layered basesheet. Thus, e.g. , the headbox 11 may be configured for forming a multi-layered basesheet as a part of a form forming process. One process for foam forming a multi-layered basesheet is illustrated in FIG. 6. The headbox 11 shown in FIG. 6, for example, is a three-chambered headbox 11 . For the headbox 11 in FIG. 6, foam-suspended fiber stock for a first layer may be supplied to the headbox 11 from a first machine chest 90, foam-suspended fiber stock for a second layer may be supplied to the headbox 11 from a second machine chest 92, and foam-suspended fiber stock for a third layer may be supplied to the headbox 11 from a third machine chest 94, which allows a three-layer foam formed product to be made (although this concept can be likewise extended to other multi-layered foam-formed products). The fiber make-up or blend of the foam-suspended fiber stock for each layer may be the same or different from each other. Continuing, in some example implementations, from the headbox 11 , the foam-suspended fiber stock layer(s) is/are issued onto the endless traveling forming wire 26 supported and driven by rolls 28 in order to form a (e.g., one-ply) three-layered foam formed product.

As described in greater detail below, to assist with forming the basesheets (both single and multilayer basesheets) in FIGS. 4 through 6, an ion-triggerable binder composition may be added to the fibers before drying the wet web. Thus, e.g., the ion-triggerable binder composition may be applied to the fibers of the wet web upstream from the through-air drying fabric 44 along the machine direction MD. Various mechanisms may be used to apply the binder composition to the fibers of the wet web.

In the example embodiment shown in FIG. 4, a sprayer 59 may apply the ion-triggerable binder composition to the wet web. The binder composition may be deposited by the sprayer 59 on one side of the wet web using, for instance, spray nozzles. Under fabric vacuum may also be used to regulate and control penetration of the binder material into the wet web. In other example embodiments, the ion-triggerable binder composition may be added to the foamed slurry of papermaking fibers upstream of the headbox 11 .

In the example embodiment shown in FIG. 6, the binder composition may be added to a machine chest 90 that is disposed upstream of the headbox 11 . The machine chest 90 may be a tank or other container for holding the foamed slurry of fibers. Moreover, in example embodiments, the machine chest 90 may include a mixer, such as an impeller, for forming the foamed slurry from water, fibers, foaming agent, the binder composition, etc. in the machine chest 90. A pump (now shown) may flow the foamed suspension of fibers and binder composition from the machine chest 90 to the headbox 11 for forming the wet web on the forming fabric 26. The wet web may thus include the binder composition at formation on the forming fabric 26.

It will be understood that each layer in a multi-layered basesheet may have a respective machine chest. Moreover, each stream of foamed slurry of fibers supplied to the headbox 11 may have a respective machine chest, indicated with reference characters 90, 92, 94 in FIG. 6. The desired amount of binder composition may be selected for each stream of foamed slurry of fibers supplied to the headbox 11 . Thus, e.g., foamed slurries with the same concentration of binder composition may be formed in each machine chest 90, 92, 94. In other example embodiments, foamed slurries with differing concentrations of binder composition may be formed in each machine chest 90, 92, 94. Thus, each layer in a multi-layered basesheet may have a respective concentration of binder composition in certain example embodiments.

In other example embodiments, the binder composition may be supplied to the headbox 11 from another tank(s) or machine chest(s) and mixed with one or more of the foamed slurries of fibers from the machine chests 90, 92, 94 prior to forming the wet web on the forming fabric 26.

In some example embodiments, the concentration of binder composition present in the foamed slurry of fibers may range from about fifty parts per million (50 ppm) to about two thousand, five hundred parts per million (2500 ppm) based on the total weight of the foamed slurry. More desirably, the concentration of binder composition present in the foamed slurry of fibers may range from about one hundred parts per million (100 ppm) to about one thousand, five hundred parts per million (1500 ppm) based on the total weight of the foamed slurry. Such concentrations of the binder composition may result in a single or multi-ply wipe substrate that has in-use integrity, but quickly disperses when soaked in tap water.

As described above, in example embodiments, the binder composition may be sprayed onto the wet web or applied to fibers upstream of a headbox. It will be understood that these two mechanisms may be used as alternatives or in combination depending upon the desired arrangement Both mechanisms allow for retention of the binder composition on the fibers in the wet web prior to drying. Thus, in certain example embodiments, after drying the wet web, the fibers in a dried web may be coated with cured binder composition throughout a thickness of the dried web due to retention of the binder composition on the fibers in the wet web.

The method shown in FIG. 4 may be a continuous production process in example embodiments. Thus, e.g., the web may be continuous between the various components described above, and the web may not be rolled onto a reel and transported to another line between components. In particular, depositing the foamed slurry of fibers at the headbox and through-air-drying drying the wet web may be performed as part of a continuous production process. Thus, the web may move continuously between the headbox and the through-air-drying drying during the method. In contrast, as noted above, a roll of dried basesheet may be transferred to a folding apparatus that treats the basesheet with the wetting composition and folds the basesheet to form wet wipes. Thus, the wetting and folding of the basesheet may be a discrete or separate process from the formation of the basesheet.

As described above, the binder composition may be added to the fibers before drying the wet web. Thus, while through-air-drying the wet web, the binder composition therein may be heated. Moreover, the binder composition may be cured. For example, the wet web may be heated to a temperature sufficient to cure the binder composition and active the adhesive properties of the binder composition while through-air-drying the wet web. In example embodiments, the through-air-drying temperature may be no greater than one hundred and two degrees Celsius (102° C), such as no greater than one hundred degrees Celsius (100° C), such as no greater than ninety-eight degrees Celsius (98° C). Such temperatures may assist with curing the binder composition, e.g., without negatively affecting dispersibility of a resulting wipe. Moreover, in some example embodiments, selecting through-air-drying temperatures in excess of the limits above can negatively affect dispensability of the resulting wipe by over-curing of certain binder compositions, which can reduce solubility of binder composition in water after flushing.

As may be seen from the above, a multi-layered foam-forming process with pulp fibers, such as NBSK fibers, is provided. An ion-triggerable or sensitive binder composition may be added onto the fibers while wet after deposition onto a forming fabric. For example, the binder composition may be added to the fiber preparation in a machine chest or be sprayed directly onto the fibers while wet after deposition onto the forming fabric. After formation, the web may be dried, e.g., on a through-air-dryer, to cure the binder composition. In example embodiments, a rush transfer may be used and/or the web may be molded on a patterned forming fabric or through-air-dryer fabric. Thus, the present subject matter may advantageously provide a pre-moistened foam-formed tissue product with an ion- triggerable binder that facilitates break-up of the product after use. Relative to conventional methods of air-laying fibers onto a preformed, dried web and then spraying binder onto the layered web, the present subject matter may advantageously reduce formation time and/or energy for dispersible wet wipes. Moreover, a drying step for the web prior to air-laying fibers may be completely omitted.

Test Methods:

The dry basis weight of the basesheet material forming the wet wipes in the stack can be obtained using the ASTM active standard 0646-96(2001 ) , Standard Test Method for Grammage of Paper and Paperboard (Mass per Unit Area), or an equivalent method.

The strength of the dispersible nonwoven sheets generated from each example can be evaluated by measuring the tensile strength in the machine direction and the cross-machine direction. Tensile strength can be measured using a Constant Rate of Elongation (CRE) tensile tester having a 1 -inch jaw width (sample width), a test span of 3 inches (gauge length), and a rate of jaw separation of 25.4 centimeters per minute after soaking the sheet in tap water for 4 minutes and then draining the sheet on dry Viva® brand paper towel for 20 seconds. This drainage procedure can result in a moisture content of 200 percent of the dry weight +/-50 percent. This can be verified by weighing the sample before each test. One-inch wide strips can be cut from the center of the dispersible nonwoven sheets 80 in the specified machine direction 24 (“MD") or cross-machine direction 25 ("CD”) orientation using a JDC Precision Sample Cutter (Thwing-Albert Instrument Company, Philadelphia, Pa., Model No. JDC3-10, Ser. No. 37333). The "MD tensile strength” is the peak load in grams-force per inch of sample width when a sample is pulled to rupture in the machine direction. The "CD tensile strength” is the peak load in grams-force per inch of sample width when a sample is pulled to rupture in the cross direction.

The instrument used for measuring tensile strength can be an MTS Systems Synergie 200 model and the data acquisition software can be MTS TestWorks® for Windows Ver. 4.0 commercially available from MTS Systems Corp., Eden Prairie, Minn. The load cell can be an MTS 50 Newton maximum load cell. The gauge length between jaws can be 3±0.04 inches and the top and bottom jaws can be operated using pneumatic-action with maximum 60 psi. The break sensitivity can be set at 70 percent. The data acquisition rate can be set at 100 Hz (i.e., 100 samples per second). The sample can be placed in the jaws of the instrument, centered both vertically and horizontally. The test can be then started and ended when the force drops by 70 percent of peak. The peak load can be expressed in grams-force and can be recorded as the "MD tensile strength” of the specimen. All of these values are for in-use tensile strength measurements.

Burst strength may be measured substantially as described in U.S. Pat. No. 5,667,635 using a tensile tester equipped with a computerized data-acquisition system that is capable of calculating peak load and energy between two predetermined distances (15-60 millimeters). The load cell should be chosen so that the peak load values fall between 10 and 90 percent of the full-scale load for the material being tested. Suitable tensile testers include the MTS Systems Synergie 200 model and the data acquisition software can be MTS TestWorks® for Windows Ver. 4.0 commercially available from MTS Systems Corp., Eden Prairie, Minn.

The burst test is carried out in a standard laboratory atmosphere of about 23° C. and about 50 percent relative humidity. The test instrument should be mounted on a table free of vibrations to avoid ending the test prematurely. The sample, soaked in tap water for 4 minutes and then draining the sheet on dry Viva® brand paper towel for 20 seconds, is draped across the opening of the sample stand and secured with the magnetic ring. The inside diameter of the sample stand is 2.5 inches and the inside diameter of the magnetic ring is 2.82 inches. The probe is aluminum and has a length of 4.5 inches, a diameter of 0.50 inch and a radius of curvature at the end of 0 25 inch. During the test, the probe is lowered onto the sample at a rate of 16 inches per minute until the sample tears. The peak load is the wet burst strength for the sample, having units of grams force (gf). A representative number of samples should be tested to obtain an average value, which is the burst strength.

The air permeability is measured in cubic feet of air per minute passing through a 38 square cm area (circle with 7 cm diameter) using a Textest FX3300 air permeability tester manufactured by Textest Ltd., Zurich, Switzerland. All tests are conducted in a laboratory with a temperature of 23+1-2° C. and 50+/-5% RH. Specifically, the moist wipe sheet is allowed to dry out and condition for at least 12 hours in the 23+1-2° C. and 50+/— 5% RH laboratory before testing. The wipe is clamped in the 7 cm diameter sheet test opening and the tester is set to a pressure drop of 125 Pa. Placing folds or crimps above the fabric test opening is to be avoided if at all possible. The unit is turned on by applying clamping pressure to the sample. The air flow under the 125 Pa pressure drop is recorded after 15 seconds of airflow to achieve a steady state value.

Dispersibility Test in Seconds (Slosh Box Test)

This method uses a bench-scaled apparatus to evaluate the breakup or dispersibility of flushable consumer products as they travel through the wastewater collection system and is based on Test IWSFG PAS 3:2018 published by the International Wastewater Services Flushability Group. In this test method, a clear plastic tank is loaded with a product and tap water or raw wastewater. The container is then moved up and down by a cam system at a specified rotational speed to simulate the movement of wastewater in the collection system. The initial breakup point and the time for dispersion of the product into pieces measuring 1 in x 1 in (25 mm x 25 mm) are recorded. This 1 in x 1 in (25 mm x 25 mm) size is a parameter that is used because it reduces the potential of product recognition. The testing can be extended until the product is fully dispersed. The various components of the product are then screened and weighed to determine the rate and level of disintegration.

The slosh box water transport simulator according to Test IWSFG PAS 3:2018 consists of a transparent plastic tank that is mounted on an oscillating platform with speed and holding time controller. The angle of incline produced by the cam system produces a water motion equivalent to 60 cm/s (2 ft/s) , which is the minimum design standard for wastewater flow rate in an enclosed collection system. The rate of oscillation is controlled mechanically by the rotation of a cam and level system and should be measured periodically throughout the test. This cycle mimics the normal back-and forth movement of wastewater as it flows through a sewer pipe.

Room temperature tap water (softened and/or non-softened) or raw wastewater (2000 mL) is placed in the plastic container/tank. The timer is set for six hours (or longer) and cycle speed is set for 26 rpm. The pre-weighed product is placed in the tank and observed as it undergoes the agitation period. For toilet tissue, add a number of sheets that range in weight from 1 to 3 grams. All other products may be added whole with no more than one article per test. A minimum of one gram of test product is recommended so that adequate loss measurements can be made. The time to first breakup and full dispersion are recorded. Note: For pre-moistened products it is recommended to flush them down the toilet and drain line apparatus prior to putting them into the slosh box apparatus or rinse them by some other means. Other pre-rinsing techniques should be described in the study records.

The test is terminated when the product reaches a dispersion point of no piece larger than 1 in x 1 in (25 mm x 25 mm) square in size or at the designated destructive sampling points. The amount of time to reach this point is measured.

Examples:

Basesheets were made using a foam forming papermaking process. In Samples #1 through #4, the basesheets were produced from a furnish consisting entirely of northern softwood kraft pulp (NSKP). In Sample #5, the basesheets were produced from a furnish consisting of both NSKP and CMC535 fibers. In Sample #6, the basesheets were produced from a furnish consisting of both NSKP and DAN U Fl L fibers.

The basesheets had a target bone dry basis weight of about seventy (70) grams per square meter (gsm). Moreover, each basesheet included three layers. The target bone dry basis weight of the fibers in a first outer layer of each basesheet was fifteen (15) gsm, the target bone dry basis weight of the fibers in a middle layer of each basesheet was forty (40) gsm, and the target bone dry basis weight of the fibers in a second outer layer of each basesheet was fifteen (15) gsm.

In Sample #5, the first and second outer layers of the basesheets consisted entirely of NSKP fibers, and the middle layer of the basesheets consisted of twenty-five percent (25%) NSKP fibers by weight and seventy-five percent (75%) CMC535 fibers by weight. In Sample #6, the first and second outer layers of the basesheets consisted of seventy percent (70%) NSKP fibers by weight and thirty percent (30%) three millimeter (3mm) DANUFIL fibers by weight, and the middle layer of the basesheets consisted of seventy percent (70%) NSKP fibers by weight and thirty percent (30%) six millimeter (6mm) DANUFIL fibers by weight.

Prior to formation of the basesheets, binder composition was added to the machine chest for each of the three layers. The binder composition included a cationic polyacrylate resulting from the polymerization of 96 mol percent methyl acrylate and 4 mol percent [2-(acryloyloxy)ethyl]trimethyl ammonium chloride.

The amount of binder composition added to the machine chests varied between samples, as indicated below in TABLE 1 . Machine Chest #1 supplied a foamed slurry of fibers and binder composition for the first outer layer, Machine Chest #2 supplied a foamed slurry of fibers and binder composition for the second outer layer, and Machine Chest #3 supplied a foamed slurry of fibers and binder composition for the middle layer. The indicated percentages are by weight of the foamed slurries.

TABLE 1

The foamed slurries contained forty (40) to sixty (60) percent air.

The tissue webs were formed on a forming fabric, vacuum dewatered, and then subjected to rush transfer of eighteen (18) percent when transferred to a transfer fabric. The web was then transferred to a through-air drying fabric. The web was then dried to approximately ninety-eight (98) percent solids before winding. The through-air drying also cured the binder composition in the basesheets. The basesheet was converted into a dispersible wipe substantially as illustrated in FIG. 3.

The exemplary dispersible wipe were subjected to physical testing, the mean results of which are summarized in TABLE 2.

TABLE 2

At various binder concentrations, the samples had sufficient strength for performing as wipes indicating retention of the binder composition during the foam-forming process. As shown for Sample #1 through #4, strength increased with respect to increasing wet-end binder composition amount when applied in a foam-forming process for basesheets; however, air permeability decreased with respect to increasing wet-end binder composition amount when applied in the foam-forming process for basesheets. Observationally, surface pattern retention noticeably improved with respect to increasing wet-end binder composition amount when applied in the foam-forming process for basesheets.

For Sample #5, high bulk properties of the CMC fibers resulted in a more permeable basesheet with greater thickness. For Sample #6, the DANUFIL fibers resulted in increased tensile strength. Observationally, the CMC fibers and/or the DANUFIL fibers may result in improved softness perception.

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.

EXAMPLE EMBODIMENTS

First example embodiment: A method for forming a tissue product, comprising: depositing a foamed slurry of fibers onto a forming surface in order to form a wet web; and drying the wet web, wherein, prior to drying the wet web, the wet web comprises an ion-triggerable binder composition applied to the fibers.

Second example embodiment: The method of the first example embodiment, further comprising introducing the ion-triggerable binder composition into the foamed slurry of fibers prior to depositing the foamed slurry of fibers onto the forming surface.

Third example embodiment: The method of the second example embodiment, wherein introducing the ion-triggerable binder composition into the foamed slurry of fibers comprises adding the ion-triggerable binder composition to a machine chest.

Fourth example embodiment: The method of any one of the first through third example embodiments, further comprising spraying the ion-triggerable binder composition onto the wet web prior to drying the wet web.

Fifth example embodiment: The method of any one of the first through fourth example embodiments, wherein drying the wet web comprises drying the wet web in a through-air dryer.

Sixth example embodiment: The method of any one of the first through fifth example embodiments, wherein drying the wet web comprises curing the ion-triggerable binder composition.

Seventh example embodiment: The method of the sixth example embodiment, wherein, after drying the wet web, the fibers in a dried web are coated with cured ion-triggerable binder composition throughout a thickness of the dried web.

Eighth example embodiment: The method of any one of the first through seventh example embodiments, wherein the ion-triggerable binder composition comprises the polymerization product of a vinyl-functional cationic monomer, a hydrophobic vinyl monomer with a methyl side chain, and one or more hydrophobic vinyl monomers with alkyl side chains of 1 to 4 carbon atoms.

Nineth example embodiment: The method of any one of the first through eighth example embodiments, wherein the fibers comprise natural pulp fibers.

Tenth example embodiment: The method of any one of the first through nineth example embodiments, wherein depositing the foamed slurry of fibers and drying the wet web are part of a continuous production process.

Eleventh example embodiment: The method of any one of the first through tenth example embodiments, further comprising, after drying the wet web, applying a wetting composition onto a dried web, the wetting composition comprising an aqueous salt solution. Twelfth example embodiment: The method of the eleventh example embodiment, wherein the aqueous salt solution comprises about 0.3% to about 10% by weight of a mono or divalent salt, the ion-triggerable binder composition insoluble in the wetting solution, the ion-triggerable binder composition dispersible in water containing up to 200 ppm Ca²⁺ ions and/or Mg²⁺ ions. Thirteenth example embodiment: A tissue product formed according to the method of any one of the first through twelfth example embodiments.

Fourteenth example embodiment: A method for forming a tissue product, comprising: forming a foamed slurry of fibers, the foamed slurry of fibers comprising an ion-triggerable binder composition; depositing the foamed slurry of fibers onto a forming surface in order to form a wet web; and drying the wet web.

Fifteenth example embodiment: The method of the fourteenth example embodiment, further comprising introducing the ion-triggerable binder composition into the foamed slurry in a machine chest.

Sixteenth example embodiment: The method of either the fourteenth example embodiment or the fifteenth example embodiment, further comprising, after drying the wet web, applying a wetting composition onto a dried web, the wetting composition comprising an aqueous salt solution.

Seventeenth example embodiment: A method for forming a tissue product, comprising: depositing a foamed slurry of fibers onto a forming surface in order to form a wet web; spraying an ion- triggerable binder composition onto the wet web; and drying the wet web.

Eighteenth example embodiment: The method of the seventeenth example embodiment, wherein drying the wet web comprises curing the ion-triggerable binder composition.

Nineteenth example embodiment: The method of either the seventeenth example embodiment or the eighteenth example embodiment, further comprising, after drying the wet web, applying a wetting composition onto a dried web, the wetting composition comprising an aqueous salt solution.

Twentieth example embodiment: A wipe formed according to the method of any of the first through nineteenth example embodiments.

Twenty-first example embodiment: A wipe, comprising: a foam-formed nonwoven web comprising fibers and a cured ion-triggerable binder composition applied to the fibers such that the fibers are coated by the cured ion-sensitive binder composition throughout a thickness of the foam- formed nonwoven web.

Claims

What Is Claimed:

1 . A method for forming a wipe, comprising: depositing a foamed slurry of fibers onto a forming surface in order to form a wet web; and drying the wet web, wherein, prior to drying the wet web, the wet web comprises an ion-sensitive binder composition applied to the fibers.

2. The method of claim 1 , further comprising introducing the ion-sensitive binder composition into the foamed slurry of fibers prior to depositing the foamed slurry of fibers onto the forming surface.

3. The method of claim 2, wherein introducing the ion-sensitive binder composition into the foamed slurry of fibers comprises adding the ion-sensitive binder composition to a machine chest.

4. The method of claim 1 , further comprising spraying the ion-sensitive binder composition onto the wet web prior to drying the wet web.

5. The method of claim 1 , wherein drying the wet web comprises drying the wet web in a through-air dryer.

6. The method of claim 1 , wherein drying the wet web comprises curing the ion-sensitive binder composition.

7. The method of claim 6, wherein, after drying the wet web, the fibers in a dried web are coated with cured ion-sensitive binder composition throughout a thickness of the dried web.

8. The method of claim 1 , wherein the ion-sensitive binder composition comprises the polymerization product of a vinyl-functional cationic monomer, a hydrophobic vinyl monomer with a methyl side chain, and one or more hydrophobic vinyl monomers with alkyl side chains of 1 to 4 carbon atoms.

9. The method of claim 1 , wherein the fibers comprise natural pulp fibers.

10. The method of claim 1 , wherein depositing the foamed slurry of fibers and drying the wet web are part of a continuous production process.

11 . The method of claim 1 , further comprising, after drying the wet web, applying a wetting composition onto a dried web, the wetting composition comprising an aqueous salt solution.

12. The method of claim 11 , wherein the aqueous salt solution comprises about 0.3% to about

10% by weight of a mono or divalent salt, the ion-sensitive binder composition insoluble in the wetting solution, the ion-sensitive binder composition dispersible in water containing up to 200 ppm Ca2+ ions and/or Mg2+ ions.

13. A wipe formed according to the method of claim 1 .

14. A method for forming a wipe, comprising: forming a foamed slurry of fibers, the foamed slurry of fibers comprising an ion-sensitive binder composition; depositing the foamed slurry of fibers onto a forming surface in order to form a wet web; and drying the wet web.

15. The method of claim 14, further comprising introducing the ion-sensitive binder composition into the foamed slurry in a machine chest.

16. The method of claim 14, further comprising, after drying the wet web, applying a wetting composition onto a dried web, the wetting composition comprising an aqueous salt solution.

17. A method for forming a wipe, comprising: depositing a foamed slurry of fibers onto a forming surface in order to form a wet web; spraying an ion-sensitive binder composition onto the wet web; and drying the wet web.

18. The method of claim 17, wherein drying the wet web comprises curing the ion-sensitive binder composition.

19. The method of claim 17, further comprising, after drying the wet web, applying a wetting composition onto a dried web, the wetting composition comprising an aqueous salt solution.

20. A wipe formed according to the method of claim 1 .

21. A wipe formed according to the method of claim 14.

22. A wipe formed according to the method of claim 17.

23. A wipe, comprising: a foam-formed nonwoven web comprising fibers and a cured ion-triggerable binder composition applied to the fibers such that the fibers are coated by the cured ion-sensitive binder composition throughout a thickness of the foam-formed nonwoven web.