MXPA01006777A - Ion-sensitive hard water dispersible polymers and applications therefor - Google Patents

Abstract

The present invention is directed to ion-sensitive, hard water dispersible polymers. The present invention is also directed to a method of making ion-sensitive, hard water dispersible polymers and their applicability as binder compositions. The present invention is further directed to fiber-containing fabrics and webs comprising ion-sensitive, hard water dispersible binder compositions and their applicability in water dispersible personal care products.

Description

SAFE DISPE WATER POLYMERS SENSITIVE TO THE ION AND APPLICATIONS TO THEM FIELD OF THE INVENTION The present invention is directed to ion-sensitive hard water dispersible polymers. The present invention is also directed to a method for making dispersible polymers in hard water sensitive to ion and its applicability to binder compositions. The present invention is further directed to fabrics and fabrics containing fibers comprising hard water dispersible binder compositions sensitive to ion and their applicability in water dispersible personal care products.

BACKGROUND OF THE INVENTION For many years the problem of availability has plagued industries, which provide disposable diapers, wet wipes, incontinent garments and women's care products. Even though much has been done to refer to this problem, one of the weak links has been the lack of capacity to create a coherent and economic fibrous tissue which dissolves or disintegrates easily in water, but still has a resistance in the use. See, for example, the description of the United Kingdom of Great Britain patent 2,241,373 and the United States of America patent number 4,186,233. Without such a product, the user's ability to dispose of the product by discharging water into a toilet is greatly reduced unless it is eliminated. In addition, the ability of the product to disintegrate in a landfill is very limited due to a large part of the components of the products, which can be either biodegradable or photodegradable but are encapsulated or bound together by plastic which degrades on a very long period of time, if at all. Therefore, if the plastic would disintegrate in the presence of water, the internal components could degrade as a result of the rupture of the plastic encapsulation or bonding.

Disposable diapers, women's care products, and adult incontinent products usually comprise a body-side liner which must quickly pass fluids, such as urine or menstrual fluids so that the fluid is absorbed. by an absorbent core of the product. Typically the body side liner is a coherent fibrous fabric which desirably has a number of characteristics such as softness and flexibility. The fibrous tissue of the side-to-body lining material is typically formed by wet or dry (by air) placement of a plurality of fibers generally at random and joining them together to form a fabric coherent with a binder. Past binders have preferred this function as well. From an environmental point of view, it can be said that the past binders have performed this function very well and that the binders tend not to degrade and therefore that the liner remains intact, severely damaging any environmental degradation of the disposable product.

Recent binder compositions have been developed which are more environmentally responsible and exhibit better water solubility than past binders. One class of binder includes polymeric materials that have an inverse solubility in water. These binders are insoluble in warm water, but are soluble in cold water, such as that found in a toilet. It is well known that a number of polymers exhibited cloudy spots or properties of inverse solubility in the aqueous medium. These polymers have been cited in various communications for various applications including (1) evaporation retarders (Japanese patent 6207162); (2) as temperature sensitive compositions, which are useful as temperature indicators due to the sharp color change associated with the corresponding temperature change (Japanese patent 6192527); (3) heat-sensitive materials that are opaque at a specific temperature and become transparent when cooled below the specific temperature (Japanese Patent Nos. 51003248 and 81035703); (4) as wound dressings with good absorbency characteristics and easy removal (Japanese patent 6233809); and (5) as materials in disposable personal care products (U.S. Patent No. 5,509,913 issued to Richard S. Yeo on April 23, 1996 and assigned to Kimberly-Clark Corporation).

Other recent binders of interest include a class of binders which are ion sensitive. Several European and United States of America patents assigned to Lion Corporation of Tokyo, Japan, describe ion-sensitive polymers comprising acrylic acid and alkyl or aryl acrylates. See U.S. Patent Nos. 5,312,883; 5,317,063; and 5,384,189; as well as European patent number 608460A1. In U.S. Patent No. 5,312,883, terpolymers are described as suitable binders for disposable nonwoven fabrics with water discharge. The described acrylic acid-based terpolymers, which comprise partially neutralized acrylic acid, butyl acrylate and 2-ethylhexyl acrylate, are suitable binders for use in non-woven disposable fabrics with water discharge in some parts of the world. However, due to the presence of a small amount of sodium acrylate in the partially neutralized terpolymer, these binders fail to disperse in water containing more than about 15 parts per million Ca 2+ and / or Mg 2 *. When placed in water containing more than 15 parts per million of Ca2 + and / or Mg2 + ions, the non-woven fabrics using the binders described above did not obtain a tensile strength greater than 30 grams per inch which negatively affects the "dispersibility" of the tissue. The proposed mechanism for failure is that each calcium ion binds with carboxylate groups either intramolecularly or intermolecularly. The intramolecular association causes the polymer chain to roll up, which eventually leads to polymer precipitation. The intermolecular association gives a crossed link. Whether the intramolecular or intermolecular associations are taking place, the terpolymer is not soluble in water containing more than 15 parts per million of Ca2 + and / or Mg2 +. Due to the strong interaction between the calcium ions and the carboxylate groups of the terpolymer, the disassociation of the complex is highly unfeasible because this association is irreversible. Therefore, the polymer described above is exposed to a solution of high concentration of Ca2 + and / or Mg2"*" for about 8 hours or more will not be dispersed in water even if the calcium concentration decreases. This limits the application of polymer as a disposable binder material with water discharge because most areas throughout the United States of America have hard water which contains more than 15 parts per million of Ca2 + and / or Mg2 +.

Although many patents describe various temperature and ion sensitive compositions for disposable materials with water discharge, there is a need for disposable water discharge products that possess softness, three dimensionality and elasticity; the transmission and structural integrity in the presence of body fluids at body temperature: and a true fiber dispersion after discharge with water discharge in the toilet so that the fibers do not get entangled with the roots of the trees or in the folds in the drainage pipes. In addition, there is a need in the art for a disposable product with water discharge that has water dispersibility in all areas of the world, including soft and hard water areas. Such a product is necessary at a reasonable cost without compromising product safety and environmental concerns, something that the products of the past have failed to do.

SYNTHESIS OF THE INVENTION The present invention is directed to ion-sensitive polymers, which have been developed to refer to the problems described above associated with ion-sensitive polymers currently available from other polymers described in the literature. The ion-sensitive polymers of the present invention have a firing property so that the polymers are insoluble in the high salt solutions but are soluble in low salt solutions, including hard water. Unlike some ion-sensitive polymers, which lose dispersibility in hard water because the ion is crosslinked by calcium ions, the polymers of the present invention are relatively insensitive to calcium ions and / or of magnesium. Accordingly, disposable water discharge products containing the polymers of the present invention maintain dispersibility in hard water.

The polymeric materials of the present invention are useful as binder and structural components for non-woven fabrics placed in the air and wet-laid for applications such as body-side lining, fluid distribution material, fluid intake material (emergence). ) or cover supply in various personal care products. The polymeric materials of the present invention are particularly useful as a binder material for disposable personal care products such as diapers, women's pads, panty liners and wet cleansing wipes. Disposable products maintain integrity during storage and use, and break and separate after disposal in the toilet when the salt concentration falls below the critical level.

The present invention also describes how to make dispersible non-woven fabrics, including a cover supply (liner), picking materials (emergence) and wet wiping cloths, which are stable to fluids having a high ionic content, using the binder compositions. polymeric polymers described above. The resulting nonwovens are disposable with water discharge and dispersible in water due to the sensitivity to the made ion, which is triggered regardless of the hardness of the water found in the • toilet throughout the United States of America and in the world.

DESCRIPTION OF PREFERRED INCORPORATIONS In order to be a trigger material of effective ion suitable for use in disposable personal care products, the material should desirably be (1) functional, for example maintaining a wet strength under controlled conditions and dissolving or dispersing rapidly in mild water. or it lasts just as it is found in toilets and toilets around the world; (2) safe (non-toxic); and (3) economic. The ion-sensitive polymers of the present invention meet the above-mentioned criteria.

Unlike the polymers of Lion and other polymers cited in the technical literature, the polymers of the present invention are non-releasable as well as water soluble having more than about 15 parts per million Ca 2+ and / or Mg 2+ at about 200 parts per million Ca2 + and / or Mg2 +. The polymers of the present invention have been formulated to minimize the potentially strong interaction between the anions of the polymers and the cations in the water. This strong interaction can be explained through the hard-soft acid base theory proposed by R. G. Pearson in the Journal of the American Chemical Society, volume 85, page 3533 (1963); or N. Isaacs in the Physics Organic Chemistry textbook, published by Longman Scientific and Technical with John Wiley & Sons., Inc., New York, 1987. Hard anions and hard cations interact strongly with one another. Soft anions and soft cations also interact strongly with one another. However, soft anions and hard cations, and vice versa, interact weakly with each other. In Lion polymers, the carboxylate anion of sodium acrylate is a hard anion, which interacts strongly with hard cations. Ca2 + and / or Mg2 +, present in hard water and moderately hard. By replacing the carboxylate anions with a softer anion, such as a softer anion, such as a sulfonate anion, such as a sulfonate anion, the interaction between the anions of a fusible polymer with ion and the hard cations, Ca2 + and / or Mg2 +, present in moderately hard and hard water is reduced.

The polymers of the present invention are formed from one or more monomers such that the resulting polymer has a "hydrophobic / hydrophilic balance" through the polymer chain. As used herein, the term "hydrophobic / hydrophilic balance" refers to a balance of hydrophobic and hydrophilic moieties that have a controlled degree of hardness or softness, as discussed above, along the polymer chain, which results in a polymer having a desired firing property in mild, moderately hard, or hard water. As used herein, the term "mild water" refers to water having a divalent ion content of less than about 10 parts per million. As used herein, the term "moderately hard water" refers to water having a divalent ion content of from about 10 to about 50 parts per million. As used herein, the term "hard water" refers to water having a divalent ion content of more than about 50 parts per million. By controlling the hydrophobic / hydrophilic balance and polymer composition, ion-sensitive polymers having a binding strength in use and a water dispersibility in hard water are produced.

The polymers of the present invention may comprise any vinyl monomers capable of free radical polymerization. At least a portion of the resulting polymer comprises one or more monomer units having a hydrophobic moiety thereon and one or more monomer units having a hydrophilic moiety thereon. Suitable monomers, which provide a degree of hydrophobicity to the resulting polymer include, but are not limited to, vinyl esters, such as vinyl acetate, alkyl acrylates; acrylonitrile; methacrylonitrile, and vinyl chloride. Suitable monomers which provide a degree of hydrophilicity to the resulting polymer include, but are not limited to monomers based on acrylamide and methacrylamide, such as acrylamide, N, N-dimethyl acrylamide, N-ethyl acrylamide, N-isopropyl acrylamide and hydroxymethyl acrylamide; N-vinyl pylorridone; N-vinylformamide; hydroxyalkyl acrylates and hydroxyalkyl methacrylates, such as hydroxyethyl methacrylate and hydroxyethyl acrylate; and monomers containing one or more of the following functional groups; hydroxy, amino, ammonium, sulfonate, ether, carboxylate, carboxylic acid, amide and sulfoamide groups. Other suitable hydrophilic and hydrophobic monomers include the vinyl monomers described in U.S. Patent No. 5,317,063 assigned to Lion Corporation of Tokyo, Japan which is hereby incorporated by reference in its entirety.

The amount of hydrophobic monomer used to produce the ion-sensitive polymers of the present invention may vary depending on the desired properties in the resulting polymer. Desirably, the mole percent of hydrophobic monomer in the ion sensitive polymer is up to about 70 mol%. More desirably, the mole percent of the hydriphobic monomer in the ion sensitive polymer is from about 15 to about 50 mol%. More desirably, the mole percent of the hydrophobic monomer in the ion sensitive polymer is from about 25 to about 40 mol%.

The ion-sensitive polymers of the present invention may have an average molecular weight, which varies depending on the final use of the polymer. Desirably, the ion-sensitive polymers of the present invention have a weight average molecular weight ranging from about 10,000 to about 5,000,000. More desirably, the ion-sensitive polymers of the present invention have a weight average molecular weight ranging from about 25,000 to about 2,000,000.

The ion-sensitive polymers of the present invention can be prepared according to a variety of polymerization methods preferably a solution polymerization method. Suitable solvents for the polymerization method include, but are not limited to, lower alcohols such as methanol, ethanol and propanol; a mixed solvent of water and one or more lower alcohols mentioned above; and a mixed solvent of water and one or more lower ketones such as acetone or methyl ethyl ketone.

In the polymerization method, any polymerization initiator can be used. The 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. Polymerization initiators suitable for use in the present invention 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 '-dimethyleneisobutylamidine), potassium persulfate, ammonium persulfate, and aqueous hydrogen peroxide. The amount of polymerization initiator can vary from about 0.01 to 5% by weight based on the total weight of the monomer present.

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

In one embodiment of the present invention, hydrophilic monomers, such as acrylic acid or methacrylic acid, are incorporated into the ion sensitive polymers of the present invention together with one or more sulfonate-containing monomers. The sulfonate anion of these monomers is softer than the carboxylate anion since the negative charge of the sulfonate anion is delocalised on three oxygen atoms and one larger sulfide atom, as opposed to only two oxygen atoms and one carbon atom smaller in the carboxylate anion. These monomers, which contain the softest sulfonate anion, are less interactive with the multivalent ions present in hard water, particularly the Ca2 + and Mg2 + ions. Suitable sulfonate-containing monomers include, but are not limited to, the sodium salt of styrene sulfonic acid (NaSS), 2-acrylamido-2-methyl-l-propanesulfonic acid (AMPS), sodium salt of 2-acrylamido-2 - methyl-1-propanesulfonic acid (NaAMPS), vinyl sulfonic acid, and sodium vinylsulfonic acid salt. To maintain the hydrophobic / hydrophilic balance of the ion sensitive polymer, one or more hydrophobic monomers are added to the polymer.

In a further embodiment of the present invention, the ion-sensitive polymers are produced from four monomers: acrylic acid, AMPS, butyl acrylate and 2-ethylhexyl acrylate. Desirably, the monomers are present in an ion-sensitive polymer at the following percent mol: acrylic acid from about 50 to less than 67 mol%; AMPS, more than 0 to about 10 mol%; butyl acrylate, at about 15 to about 28 mol%; and 2-ethylhexyl acrylate, from about 7 to about 15 mol%. More desirably, the monomers are present in an ion-sensitive polymer at the following percent mole: acrylic acid, about 57 to about 66 mole%; AMPS, about 1 to about 6 mol%; butyl acrylate, about 15 to about 28 mol%; and 2-ethylhexyl acrylate, from about 7 to about 13 mol%.

In order to further refine the hydrophobic / hydrophilic balance of the ion-sensitive polymers, at least a portion of the acid moieties, if present, along the polymer chain can be neutralized. For example, the ion-sensitive polymer described above comprising four different monomers may be partially or completely neutralized to convert some or all of the AMPS to NaAMPS. Any inorganic base or organic base can be used as a neutralizing agent to neutralize the acid component of the ion sensitive polymers. Examples of neutralizing agents include, but are not limited to, inorganic bases such as sodium hydroxide, potassium hydroxide, lithium hydroxide and sodium carbonate, and amines such as monoethanolamine, diethanolamine, diethylaminoethanol, ammonia. , trimethylamine, triethylamine, tripropylamine, morpholine. Preferred neutralizing agents include ethanolamines, sodium hydroxide, potassium hydroxide or a combination thereof.

In a further embodiment of the present invention, the ion-sensitive polymers described above are used as a binder material for the disposable and / or non-disposable products. In order to be effective with binder material in disposable products with water discharge through the United States of America, the ion-sensitive polymers of the present invention remain stable and maintain their integrity while they are dry or at high ion concentrations. monovalent and / or multivalent, but they become soluble in water containing up to about 200 parts per million of Ca2 + ions. Desirably, the ion-sensitive polymers of the present invention are insoluble in a salt solution containing at least about 0.3% by weight of one or more organic and / or inorganic salts containing monovalent and / or multivalent ions. More desirably, the ion-sensitive polymers of the present invention are insoluble in a salt solution containing from about 0.3% by weight to about 5.0% by weight of one or more inorganic and / or organic salts containing monovalent ions and / or multivalent. Even more desirably, the ion-sensitive polymers of the present invention are insoluble in a salt solution containing from about 0.5% by weight to about 3.0% by weight of one or more inorganic and / or organic salts containing ions monovalent and / or multivalent. Suitable monovalent and / or multivalent ions include but are not limited to Na + ions, K + ions, Li + ions, NH4 + ions, Cl + ions, Ca2 + ions, Mg2 + ions, Zn2 + ions, C032 + ions, and combinations thereof.

Based on a recent study conducted by the American Chemical Society, the hardness of water across the United States varies greatly, with the concentration of CaC03 varying from close to zero for mild water to around 500 parts per million. CaCO3 (about 200 parts per million of Ca2 * ion) for very hard water. To ensure dispersibility of the polymer throughout the country, the ion-sensitive polymers of the present invention are desirably soluble in water containing up to about 50 parts per million Ca 2+ and / or Mg 2+ ions. More desirably, the ion-sensitive polymers of the present invention are soluble in water containing up to about 100 parts per million Ca 2+ and / or Mg 2+ ions. Even more desirably, the ion-sensitive polymers of the present invention are soluble in water containing up to about 150 parts per million Ca 2+ and / or Mg 2+ ions. Even more desirably, the ion-sensitive polymers of the present invention are soluble in water containing up to about 200 parts per million Ca 2+ and / or Mg 2+ ions.

The binder formulas of the present invention can be applied to any fibrous substrate. The binders are particularly suitable for use in water dispersible products. Suitable fibrous substrates include, but are not limited to, non-woven and woven fabrics. In many embodiments, personal care products, particularly preferred substrates, are non-woven fabrics. As used herein, the term "non-woven fabric" refers to a fabric having a structure of individual fibers or filaments randomly arranged in a mat-like shape. Non-woven fabrics can be made from a variety of processes including, but not limited to, air-laid processes, wet-laid processes, hydroentanglement processes, basic fiber bonding and carding, and solution spinning.

The binder composition can be applied to the fibrous substrate by any known process of application. Suitable processes for applying the binder material include, but are not limited to printing, spraying, impregnation or any other technique. The amount of binder composition can be dosed and uniformly distributed within the fibrous substrate or it can be distributed non-uniformly within the fibrous substrate. The binder composition can be distributed through the entire fibrous substrate or it can be distributed within a multiplicity of closely spaced areas. In most embodiments, the uniform distribution of the binder composition is desired.

For ease of application to the fibrous substrate, the binder can be dissolved in water, or in an aqueous solvent such as methanol, ethanol, acetone or the like with water being the preferred solvent. The amount of binder dissolved in the solvent may vary depending on the polymer used and the application of the fabric. Desirably, the binder solution contains up to about 25% by weight of solids of binder composition. More desirably, the binder solution contains from about 10 to 20% by weight of the solids of the binder composition. Plasticizers, perfumes, coloring agents, antifoams, bactericides, surfactants, thickeners, fillers, glutinizers, debanders, and similar additives can be incorporated into the binder solution if desired .

Once the binder solution is applied to the substrate, the substrate is dried by any conventional means. Once it is dry, the coherent fibrous substrate exhibits an improved tensile strength as compared to the tensile strength of wet laid or untreated dry substrates, and still has the ability to quickly separate or disintegrate when place in the soft or hard water having a relatively low monovalent and / or multivalent ion concentration and stir. For example, the dry tensile strength of the fibrous substrate can be increased by at least 25% compared to the dry tensile strength of the untreated substrate not containing the binder. More particularly, the dry tensile strength of the fibrous substrate can be increased by at least 100% compared to the dry tensile strength of the untreated substrate not containing the binder. More particularly, the dry tensile strength of the fibrous substrate can be increased by at least 500% compared to the dry tensile strength of the untreated substrate not containing the binder.

A desirable feature of the present invention is that the improvement in tensile strength is effected wherein the amount of the binder composition present, aggregated in the resulting fibrous substrate, exhibits only a small part by weight of the entire substrate. The amount of "aggregate" may vary for a particular application; however, the optimum amount of aggregate results in a fibrous substrate which has an integrity while in use and also disperses rapidly when agitated in water. For example, binder components are typically from about 5 to about 65%, by weight, of the total weight of the substrate. More particularly, the binder components may be from about 10 to about 35% by weight of the total weight of the substrate. Even more particularly, the binder components can be from about 10 to about 25% by weight of the total weight of the substrate.

The non-woven fabrics of the present invention have good tensile strength in use, as well as good ion fusibility. Desirably the non-woven fabrics of the present invention are resistant to abrasion and retain a significant tensile strength in aqueous solutions containing more than about 0.5% by weight of NaCl or a mixture of monovalent and multivalent ions, wherein the Multivalent ion concentration is greater than about 500 parts per million. Nonetheless, non-woven fabrics are dispersible in soft to moderately hard to hard water. Due to this latter property, the non-woven fabrics of the present invention are very suitable for disposable products such as sanitary napkins, diapers and dry and pre-moistened wipes, which can be thrown into a flushing toilet after use. in any part of the world.

The fibers that form the fabrics can also be made from a variety of materials including natural fibers, synthetic fibers and combinations thereof. The choice of fibers will depend on for example, the final intended use of the finished fabric and the cost of the fiber. For example, suitable fibrous substrates may include, but are not limited to, natural fibers such as cotton, linen, jute, cotton, wool, wool pulp, etc. Similarly, regenerated cellulosic fibers such as viscose rayon and cupramonium rayon, modified cellulosic fibers such as cellulose acetate, or synthetic fibers such as those derived from polyesters, polyamides, polyacrylics, etc., alone or in combination with others they can similarly be used. Mixtures of one or more of the above-mentioned fibers can also be used if desired.

The length of the fibers is important to produce the fabrics of the present invention. In some embodiments such as disposable products with water discharge the length of the fiber is more important. The minimum length of the fibers will depend on the method selected to form the fibrous substrate. For example, where the fibrous substrate is formed by the carding, the length of the fiber should usually be at least about 42 millimeters in order to ensure uniformity. When the fibrous substrate is formed by air laying or wet laying processes, the length of the fiber may desirably be from about 0.2 to 6 millimeters. Even though fibers having a length greater than 50 millimeters are within the scope of the present invention, it has been determined that when a substantial amount of fibers having a length greater than about 15 millimeters is placed in a disposable fabric with discharge of Water, even though the fibers will disperse and separate in water, their lengths tend to form fiber "cords" which are undesirable when they are discharged with water discharge into domestic toilets. So, for these products it is desirable that the fiber length be about 15 millimeters or less so that the fibers will not have a tendency to form a rope when they are discharged with water discharge through a toilet. Although fibers of various lengths are applicable in the present invention, the fibers desirably are of a length of less than about 15 millimeters so that the fibers readily disperse one another when in contact with water.

The fabrics of the present invention can be formed of a single layer or of multiple layers. In the case of multiple layers, the layers are generally placed in a juxtaposed or surface-to-surface relationship and all or a portion of the layers can be joined to the adjacent layers. The non-woven fabrics of the present invention can also be formed from a plurality of separate non-woven fabrics wherein the separate non-woven fabrics can be formed of single or multiple layers. In those cases where the non-woven fabric includes multiple layers, the entire thickness of the non-woven fabric can be subjected to a binder application or each individual layer can be separately subjected to a binder application and then combined with other layers in a juxtaposed relationship to form the finished non-woven fabric.

In one embodiment, the fabric substrates of the present invention can be incorporated into the body fluid and cleaning absorbent products such as sanitary napkins, diapers, surgical bandages, tissue, wet cleansing wipes and the like. These products may include an absorbent core, comprising one or more layers of an absorbent fibrous material. The core may also comprise one or more layers of a fluid permeable element such as a fibrous tissue, gauze, plastic net, etc. These are generally useful as wrapping materials for containing the core components together. Additionally, the core may comprise a fluid impervious member or barrier means to preclude the passage of fluid through the core and onto the exterior surfaces of the product. Preferably, the barrier means are also dispersible in water. A polymer film has essentially the same composition as the aforementioned water dispersible binder and is particularly well suited for this purpose. In accordance with the present invention, the polymer compositions are useful for forming each of the aforementioned product components including the absorbent core layers, the fluid permeable element, the wrapping materials and the barrier means or waterproof elements. fluid.

The binder formulas are particularly useful for the binder fibers of non-woven fabrics placed by air. These air-laid materials are useful for side-to-body liners, fluid distribution materials, fluid intake materials, such as emergence material, wrapping sheet and cover supply for various products for the Personal care dispersible in water. The materials placed by air are particularly useful for use as a pre-wetted cleaning cloth. Base weights for non-woven fabrics placed by air can vary from about 20 to about 200 grams per square meter (gsm) with basic fibers having a denier of 2-3 and a length of about 6-15 millimeters . Picking materials require better elasticity and superior fluffiness so that basic fibers having about 6 denier or more are used to make these products. A desirable final density for the pick-up materials is between about 0.025 grams per cubic centimeter (g / cc) to about 0.050 grams per cubic centimeter. The fluid distribution materials can have a higher density, in the desired range of about 0.10 to about 0.20 grams per cubic centimeter using lower denier fibers, more desirably the fibers have a denier of less than about 1.5. Cleaning cloths generally have a density of about 0.05 grams per cubic centimeter to about 0.2 grams per cubic centimeter and a basis weight of about 30 grams per square meter to about 90 grams per square meter.

A particularly interesting embodiment of the present invention is the production of pre-wetted cleaning cloths or wet cleaning cloths of the above-described ion-sensitive polymers and fibrous materials. For cleaning wipes, the non-woven fabric is desirably formed of relatively short fibers such as wood pulp fibers. The minimum length of the fibers depends on the method selected to form the non-woven fabric. Where the non-woven fabric is formed by the dry wet method, the fiber length is desirably from about 0.1 millimeter to 15 millimeters. Desirably, the non-woven fabric of the present invention has a relatively low wet cohesive strength when it is not joined together by an adhesive or binder material. When such non-woven fabrics are joined together by an adhesive, which loses its bond strength in the water of the tap and in the drainage water, the fabric will be easily broken by the stirring provided by the discharge of water and the movement to through the drainage pipes.

The finished cleaning cloths can be individually packaged, preferably in a folded condition, in a moisture-proof wrapping or packaged in containers holding a desired number of sheets in a waterproof package with a wetting agent applied to the cleaning cloth. In relation to the weight of the dried cloth, the cleaning cloth may contain from about 10% to about 400% and desirably from about 100% to about 300% of the wetting agent. The cleaning cloth must maintain its desired characteristics over the periods of time involved in storage, transportation, retail display and storage by the consumer. Therefore, life on the shelf can vary from two months to two years.

Various forms of the waterproof wrappers to contain the wet packed materials such as wipes and wipes and the like are well known in the art. Any of these can be used to pack the pre-moistened cleaning cloths of the present invention.

In an embodiment of the present invention, the wet cleaning cloths comprising the above-described nonwoven fabric are stored in an impermeable package and saturated with a salt solution containing more than about 0.5% by weight of one or more monovalent salts , such as NaCl or KCl.

Desirably, the salt solution contains about 0.5 to 3.0% by weight of one or more monovalent salts. In another embodiment, the wet cleaning cloths are saturated with a salt solution containing more than about 500 parts per million of one or more multivalent ions, such as ions.

Ca2 + or Mg2 +. In a further embodiment, the wet cleaning wipes are saturated with a salt solution containing more than about 0.5% by weight of one or more monovalent salts in combination with one or more multivalent ions, wherein the concentration of multivalent ions is higher of around 500 parts per million. Desirably, the wet wiping cloths have a tensile strength in the use of at least 100 grams per inch, and a tensile strength of less than about 30 grams per inch after being soaked in water having a concentration of Ca2 + and / or Mg2 + ions of about 50 parts per million for about one hour. More desirably, the wet wiping cloths have a tensile strength in use of at least 300 grams per inch and a tensile strength of less than about 30 grams per inch after being soaked in water having an ion concentration. of Ca2 + and / or Mg2 + of about 50 parts per million for about one hour. In a further embodiment, the wet cleaning wipes desirably possess a tensile strength in use of at least 200 grams per inch and a tensile strength of less than about 20 grams per inch after being soaked in water having a concentration of Ca2 + and / or Mg2 + ions of about 200 parts per million for about one hour. Even more desirably, the wet cleaning cloths have a tensile strength in use of at least 300 grams per inch and a tensile strength of less than about 20 grams per inch after being soaked in water having a concentration of Ca2 + ions and / or Mg2 + of about 200 parts per million for about one hour.

The non-woven fabrics of the present invention can also be incorporated into such body fluid absorbent products as sanitary napkins, diapers, surgical bandages, tissue and the like. The binder is such that it will not dissolve when it comes into contact with body fluids since the concentration of ions in body fluids is above the level necessary for dissolution. The non-woven fabric retains its structure, smoothness and exhibits satisfactory firmness for practical use. However, when it comes into contact with water having a concentration of multivalent ions, such as Ca2 + and Mg2 + ions, of up to about 200 parts per million, the binder is dispersed. The non-woven fabric structure is then easily broken and dispersed in the water.

In an embodiment of the present invention, the tensile strength in the use of a non-woven fabric is increased by forming the non-woven fabric with a binder material comprising an ion-sensitive polymer of the present invention and subsequently applying one or more monovalent and / or multivalent salts to the non-woven fabric. The salt can be applied to the non-woven fabric by any method known to those of ordinary skill in the art including, but not limited to the application of a solid powder on the cloth and spraying a salt solution on the cloth. The amount of salt can vary depending on a particular application.

However, the amount of salt applied to the fabric is typically from about 0.1% by weight to about 10% by weight of salt solids based on the total weight of the fabric. The salt-containing fabrics of the present invention can be used in a variety of fabric applications including, but not limited to, women's pads and diapers.

Those skilled in the art will readily understand that the binder formulas and fibrous substrates of the present invention can be advantageously employed in the preparation of a wide variety of products, including but not limited to absorbent personal care products designed to make contact with the fluids of the body. Such products may only comprise a single layer of a fibrous substrate or may comprise a combination of elements as described above. Although the binder formulas and fibrous substrates of the present invention are particularly suitable for personal care products, binder formulas and fibrous substrates can be advantageously employed in a wide variety of consumer products.

The present invention is further illustrated by the following examples which should not be considered in any way as imposing limitations on the scope thereof. On the contrary, it should be clearly understood that several other additions, modifications and equivalents thereof must be used which, after reading the description given here, may arise to those experts in the art without departing from the spirit of the present. invention and / or scope of the appended claims.

EXAMPLE 1 Preparation of Ion-Sensitive Polymers Acrylic acid (43.3 grams, 0.60 mole), AMPS (10.7 g, 0.052 mole), butyl acrylate (35.2 g, 0.27 mole) and 2-ethylhexyl acrylate (20 g, 0.11 mole) were dissolved in 55 grams of a mixture of acetone / water (70/30). One initiator, 2,2-azobisisobutyronitrile (AIBN) (0.51 g, 3.1 x 10"3 mol), was dissolved in 20 milliliters of acetone.The monomer solution was deoxygenated by bubbling N2 through the solution for 20 minutes. A 1,000 milliliter three-necked round bottom bottle, equipped with a condenser, two addition funnels and a magnetic stirrer, was added with 120 grams of an acetone / water mixture (70/30) .The solvent was heated to a reflux soft under nitrogen.The monomers and the initiator were added simultaneously from the addition funnels over a period of two hours.The polymerization was allowed to proceed for an additional period of two hours., at the end of which, the addition funnels and the condenser were replaced with a distillation head and a mechanical stirring rod to remove the acetone. A stable stream of N: was maintained during the distillation while the temperature was gradually increased from about 65 ° C to about 90 ° C. When the distillation was complete, 400 grams of deionized water were added to reduce the viscosity of the solution of the polymer. A cloudy but uniform solution was obtained.

A total of 12 polymers (samples 1-12) were synthesized using the procedure described above. The NaOH (2.1 g, 0.052 mol) in 20 milliliters of water were added at room temperature to neutralize the AMPS component in samples 3-7 and 9-12. The compositions of samples 1-12 are summarized in Table 1 below. All percentages are given in a mole percent.

Table 1. Ion Sensitive Polymer Compositions COMPARATIVE EXAMPLE 1 Comparative Test of a Polymer Supplied by Lion Corporation A Lion polymer was supplied from the Lion Corporation and tested as infringed in the examples given below. The polymer was one of the polymers described and claimed in U.S. Patent No. 5,312,883 assigned to Lion Corporation.

COMPARATIVE EXAMPLE 2 Preparation of a Lion Corporation Polymer A Lion polymer was produced using the polymerization process outlined in Example 2 of U.S. Patent No. 5,312,883. The following monomers were used: acrylic acid (50 g, 0.69 mol), butyl acrylate (25 g, 0.20 mol) and 2-ethylhexyl acrylate (25 g, 0.14 mol). The polymer was neutralized with 0.1 mol of sodium hydroxide.

EXAMPLE 2 Sensitivity to Improved Hard Water of a Non-Neutralized Polymer Compared to Lion Polymers The sensitivity of the unneutralized polymers of Example 1 and of the Lion polymers of Comparative Examples 1 and 2 with the divalent cations present in the hard water was measured. Samples 1, 2 and 8 of Example 1 and the Lion polymer were placed in a number of CaCl 2 solutions at a Ca 2+ concentration ranging from 100 to 1,000 parts per million. After soaking for one hour, the solubility of each polymer was noted. The solubility results are given below in Table 2.

Table 2. Solubility Results Solubility in Ca Note: 1: very light turbidity; 2: light turbidity; 3: moderate turbidity (cloudy but still light being able to penetrate through the solution); 4: severe turbidity (milky); 5: Heavy precipitation (solid gel formation).

The results in Table 2 indicated that the polymers containing AMPS were much less sensitive to the concentration of Ca2 + ion in relation to the Lion polymers. However, with a sufficient amount of Ca2 + ion present (around 1,000 parts per million), all polymers will "salt out" of the solution. In other words all polymers will be insoluble in the solution of 1,000 parts per million Ca2 + ion.

An additional dilution experiment supported these results. The five precipitates were then removed from the solutions of 1,000 parts per million Ca 2+ and placed in deionized water. Samples 1, 2 and 8 which contained AMPS were redissolved in the deionized water; however, the Lion polymers (from Comparative Examples 1 and 2 did not do so due to the irreversible cross-linking of the sodium acrylate sites.

The reduction in ion sensitivity of polymers containing AMPS to multivalent ions was found to be not limited to Ca2 * ions. In a separate experiment, samples 2 and 8 together with the Lion polymers of Comparative Examples 1-2 were precipitated in a ZnCl 2 solution having a Zn 2 ion concentration of 5,000 parts per million. 8 were redissolved in water, but Lion's polymers did not, which suggested that in general, polymers containing AMPS were less sensitive to divalent cations and did not form a permanent cross-linking structure.

EXAMPLE 3 Agglutination Resistance Test of Polymers Containing AMPS Compared to Polymer Lion The agglutination resistance of polymers containing AMPS was tested in Ca2 + solutions of 100 and 200 parts per million. The five polymers (samples 1, 2 and 8 and the Lion polymers of Comparative Examples 1 and 2) were applied through a twisted wire rod number 20 to five non-woven fabrics placed in water dispersible in water and identical composed of rayon fibers BFF (1.5 dx) 25 mm). The fabric samples were dried in a forced air oven at 50 ° C. The aggregate level was between about 55 and 61% by weight based on the total weight of the fabric. The non-woven sheets were cut to provide 1 inch x 3 inch strips of each sheet. The dry samples were placed directly into the Ca2 * ion solutions. The strips were tested for the tensile strength after soaking in solution for one hour according to the following test method.

The strips were mounted on a mini-tension tester with a 2-inch gap. The resistance was tested at a speed of 18 centimeters per minute and the peak peak load was recorded. The results are summarized in Table 3 given below.

Table 3 Resistance to Tension Resistance (g / inch) in Ca2 'Solutions (ppm) The results in Table 3 again illustrate the reduced sensitivity of polymers containing AMPS to Ca 2+ ions. The binder compounds of sample 1 and 2 were dispersible in 100 parts per million solutions of Ca2"and a binder composed of sample 8 was dispersible in a solution containing up to 200 parts per million Ca2". These polymers showed a significant improvement over the Lion polymers.

EXAMPLE 4 Adjust the pH of Solutions Containing Ion-Sensitive Polymers The pH of the solution of samples 1, 2 and 8 of example 1 was found to be very low, ranging from 1.7 for sample 8 to 2.1 for sample 1, due to the presence of sulfonic acid groups. Low pH is undesirable in applications such as wet cleaning cloths not only because this causes yellowing of the pulp substrate in the drying process but also because it can irritate the skin during use. To adjust the pH of these solutions, equimolar amounts of NaOH were added to neutralize the AMPS. The pH of the solutions rose to around 3.1-3.3, a more desirable pH range for skin health, which eliminates yellowing of the fibrous substrate during drying.

EXAMPLE 5 Effect of Neutralization on the Dispersion Rate of Ion-Sensitive Polymers Five polymer solutions containing three polymers of example 1 (samples 1-3) and the Lion polymers of comparative examples 1-2 were applied through a twisted wire rod number 20 to five wet-laid non-woven fabrics dispersed in water and identical composite rayon fibers BFF (1.5 dx 25 millimeters). The fabric samples were dried in a forced air oven at 50 ° C. The aggregate level was between about 55 and 61% by weight based on the total weight of the fabric. The non-woven sheets were cut to provide 3-inch inch strips of each sheet.

The strips were placed in deionized water. The dispersion time (for example the time in which each fabric sample had essentially a tensile strength of zero) was recorded. The results are given in Table 4 given below.

Table 4. Deionized Water Dispersion Time As shown in Table 4, the strips containing the Lion polymer lost all their strength in about three minutes, indicating good dispersibility in the deionized water. The strips formed of the polymers containing AMPS had poor dispersibility in the deionized water. However, the strips formed of the polymer containing NaAMPS had good dispersibility in the deionized water.

In order to determine the effect of the concentration of Ca2 + ion on the dispersibility of sample 3, the strips of sample 3 were tested for resistance to stress after soaking for up to one hour in solutions containing from 0 to 200 parts per million of Ca2 + ion. The sample was found to be stable at 0.9% by weight of a NaCl solution and was dispersible in deionized water in less than 10 minutes. In a Ca2 + solution of 200 parts per million, the strip had an initial strength of about 275 grams per inch. In a Ca2 + solution of 100 parts per million, the strip had the strength of less than about 50 grams per inch after one hour and became unrecognizable after two hours. It was concluded that even when the neutralization increased the dispersion rate significantly, it did not adversely alter the resistance characteristics and Ca2 + sensitivity of the ion-sensitive polymers of the present invention.

EXAMPLE 6 Water Dispersibility Test of Non-Woven Fabrics Ten polymer solutions containing eight polymers of example 1 (samples 1 and 3-9) and the Lion polymers of comparative examples 1-2 were applied through a rolled wire rod number 20 to ten of the non-woven wires placed in wet, water dispersible and identical composed of BFF rayon fibers (1-5 dx 25 millimeters). The fabric samples were dried in a forced air oven at 50 ° C. The aggregate level was between about 55 and 61% by weight based on the total weight of the fabric. The non-woven sheets were cut to provide 1 inch x 3 inch strips of each sheet. The strips were tested for water dispersibility according to the following procedure.

The 1 inch x 3 inch strips of the ten non-woven sheets were soaked in solutions having a Ca 2+ ion concentration of from 100 to 1,000 parts per million for about one hour. The samples were removed from the solutions and tested for the tensile strength in the machine direction using the procedure outd above. The samples having a low tensile strength showed good dispersibility in water. The results of the test are given below in Table 5.

Table 5. Tension Resistance of Ion-Sensitive Polymers in Ca2 + Ion Solutions (ppm Ca2 + Ion (g / pulse) As shown in Table 5, the tensile strength of the non-woven fabrics formed of the polymers containing AMPS or NaAMPS, in most cases, decreased as the Ca2 * ion concentration was decreased. By control the hydrophobic / hydrophilic balance in the composition of the polymeric binder, non-woven fabrics having good dispersibility in water were produced as identified by a low tensile strength in the solutions having a Ca2 + ion concentration of 100 or 200. parts per million (see polymer samples 4, 7, 8 and 9 given above).

In contrast, water dispersibility or ion tripping of Lion polymers was found to be unacceptable for waste discharge applications. The non-woven fabrics formed from the Lion polymers had an extremely high tensile strength (> 281 g / inch) in solutions having a Ca 2+ ion concentration of 100 or 200 parts per million. Given these results, the non-woven fabrics formed from Lion polymers would not be suitable in disposable products with water discharge in hard water areas.

EXAMPLE 7 Variation of Polyamide Compositions Containing NaAMPS to Affect Stress Resistance in NaCl Solutions and Dispersability in Ca2 + Solutions Ten non-woven fabrics comprising the binder materials formed of eight polymers of Example 1 (samples 1-7 and 9-12) and the Lion polymers of Comparative Examples 1-2 were prepared as in Example 7. The resistance in use and the dispersibility of the fabrics containing NaAMPS and of the fabrics containing polymer Lion was measured as described above.

The 1 inch x 3 inch strip of the ten non-woven sheets were tested on a machine using the test method described above. The strength in use of the polymeric binder was measured as the tensile strength in the machine direction of each sample tested in a 0.9% by weight solution of NaCl or in a salt solution of 1.5% by weight of NaCl. after soaking overnight at room temperature, unless otherwise indicated.

To determine the dispersibility of some of the pre-packed samples, the sample was transferred after soaking in one of the salt solutions given above to a solution containing a Ca2 * ion concentration of from 100 to 200 parts per million Ca2 * for one hour, and tested for resistance to stress. The samples having a low tensile strength showed good dispersibility in water. The test results are given below in Table 6.

Table 6. Tension Resistance of Ion-Sensitive Polymers in Ca2 + Ion Solutions (Ca2 + ppm) and NaCl Solutions (g / inch) Note * The samples were tested after soaking for one hour in the designated solution.

** The dried samples were pre-packed overnight in a NaCl solution and then placed directly in a Ca2 + solution and tested after 1 hour.

As shown in Table 6, the fabric samples formed of polymers containing NaAMPS had very low resistance to the solution tension of 0.9% by weight of NaCl. In contrast, the fabric samples formed from the Lion polymers had high tensile strength. In the 1.5% by weight NaCl solution, the fabric samples formed from the polymers containing NaAMPS had good tensile strength. The increase in tensile strength can be attributed to an increase in the salting out effect of the polymers containing NaAMPS.

In addition, Table 6 shows that most fabric samples formed of polymers containing NaAMPS lost all or a significant part of the tensile strength after soaking in a 100 parts per million Ca 2+ ion solution. Also, fabric samples 11 and 12 lost their tensile strength after being transferred and soaked in a Ca2 + ion solution of 200 parts per million, indicating good dispersibility in water. In contrast, the fabric samples formed from the Lion polymers did not lose their tensile strength in 100 parts per million or 200 parts per million solutions of Ca2 * ion, indicating poor dispersibility.

EXAMPLE 8 Effect of Divalent I nites on the Use of Stress Resistance in the Use and Dispersibility in Water of Non Woven Fabrics United with Polymers Containing NaAMPS Example 7 indicated that the polymers containing NaAMPS, which are dispersible in 200 parts per million Ca 2+ solution, have a tensile strength in acceptable use only in higher NaCl concentrations (greater than 0.9% by weight of NaCl) . In order to possibly increase the tensile strength of these binders at a lower NaCl concentration, salts containing divalent cations such as Ca2 + and Zn2 * were added to the NaCl solutions due to their superior outward salting capacity. Samples 3-7 and 9 of Example 1 were used as a binder material for the non-woven fabric comprising rayon fabrics BFF as described above. The tensile strength of the fabrics was measured after soaking in the variety of solutions. The results of the test are summarized in Table 7 given below.

Table 7. Stress Resistance of Ion-Sensitive Polymers in Mixed Salt Solutions (g / inch) The results in Table 7 indicate that the polymers containing NaAMPS are stable in all test solutions, demonstrating the effectiveness of divalent ions to stabilize the polymer, even at low NaCl concentrations. In some cases, the polymers can be stabilized with the divalent ion salt alone. As further shown in Table 7 compared to Table 6, Ca2 * ions are more effective in stabilizing the polymers than Na * or Zn2 * ions, as demonstrated by the higher tensile strength values in NaCl solutions containing Ca2 * ions as opposed to NaCl solutions containing Zn2 * ions at the comparable concentration level.

EXAMPLE 9 The Solubility of Disparable Polymers with Ion as Measured by the Percentage of Weight Loss in a Divalent Ion Salt Solution The films were produced from three polymers of example 1 (samples 9, 10, and 12) and the Lion polymer from comparative example 1. The heavy samples of each film were placed in a solution of 1.5% by weight of NaCl for 24 hours. The samples were removed and weighed to determine the percent loss by weight of each sample. Similarly, the heavy samples of each film were placed in a solution containing 200 parts per million of Ca2 * / Mg2 * ions (2 parts of Ca2 * to 1 part of Mg2") and were agitated by movement for about 2 hours. Samples were removed and weighed to determine the weight loss percentage of each sample.

Table 8. Percent Weight Loss of Ion-Sensitive Polymer Films in Sales Solutions All five samples showed 0% weight loss after being soaked in 1.5% NaCl for 24 hours, indicating that all samples were essentially insoluble in the NaCl solution. In the Ca2 * / Mg2 * solution, the Lion polymer had very little weight loss, indicating that the Lion polymer was essentially insoluble in the solution. However, the polymers of the present invention had a weight loss of at least 34% in the Ca2 * / Mg2 * solution, indicating that the samples formed of the ion-triggerable polymers of the present invention were soluble in the solution. In addition, sample 12 had a 100% weight loss indicating substantial solubility in the Ca2 * / Mg2 * solution.

The results in Table 8 further confirm the results of Example 6. In particular, the water dispersibility or ion tripping of the Lion polymer was found to be unacceptable for disposable applications with water discharge, especially the disposable applications with discharge in water in hard water areas. However, water dispersibility or ion tripping of the polymers of the present invention was found to be acceptable for waste applications with water discharge, including waste applications with water discharge in hard water areas. the examples described above are of preferred embodiments and are not intended to limit the scope of the present invention in any way. Various modifications and other embodiments and uses of the described water dispersible polymers, apparent to those of ordinary skill in the art are also considered to be within the scope of the present invention.

Claims (34)

R E I V I N D I C A C I O N S

1. An ion-sensitive polymer, wherein the polymer is insoluble in a neutral salt solution containing at least about 0.3% by weight of salt, said salt comprising one or more monovalent or multivalent ions; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 500 parts per million of one or more multivalent ions.

2. The ion-sensitive polymer as claimed in clause 1, characterized in that the polymer is insoluble in a neutral salt solution containing at least about 0.3% by weight of salt, said salt comprising one or more monovalent ions or multivalent; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 200 parts per million of one or more multivalent ions.

3. The ion-sensitive polymer as claimed in clause 2, characterized in that the polymer is insoluble in a neutral salt solution containing at least about 0.3% by weight of salt, said salt comprising one or more monovalent ions or multivalent; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 150 parts per million of one or more multivalent ions.

4. The ion-sensitive polymer as claimed in clause 3, characterized in that the polymer is insoluble in a neutral salt solution containing at least about 0.3% by weight of salt, said salt comprising one or more monovalent ions or multivalent; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 100 parts per million of one or more multivalent ions.

5. The ion-sensitive polymer as claimed in clause 4, characterized in that the polymer is insoluble in a neutral salt solution containing at least about 0.3% by weight of salt, said salt comprising one or more monovalent ions or multivalent; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 50 parts per million of one or more of the multivalent ions.

6. The ion-sensitive polymer as claimed in clause 1, characterized in that the polymer is insoluble in a neutral salt solution containing from about 0.5% by weight to about 5.0% by weight of the salt.

7. The ion-sensitive polymer as claimed in clause 1, characterized in that the polymer is insoluble in a neutral salt solution containing from about 0.5% by weight to about 3.0% by weight of the salt.

8. The ion-sensitive polymer as claimed in clause 1, characterized in that the multivalent ions comprise Ca2 * ions, Mg2t ions, Zn2 * ions or a combination thereof.

9. The ion-sensitive polymer as claimed in clause 1, characterized in that the monovalent ions comprise Na * ions, Li * ions, K * ions, NH4 + ions or a combination thereof.

10. The ion sensitive polymer as claimed in clause 1, characterized in that the polymer is formed of one or more monomers selected from styrenesulfonic acid (SS), the sodium salt of styrene sulfonic acid (NaSS), 2-acrylamido-2 -methyl-l-propanesulfonic acid (AMPS), a sodium salt of 2-acrylamido-2-methyl-l-propanesulfonic acid (NaAMPS), vinyl sulfonic acid, sodium salt of vinylsulfonic acid or combinations thereof.

11. The ion-sensitive polymer as claimed in clause 1, characterized in that the polymer comprises: acrylic acid, methacrylic acid, or a combination thereof, AMPS or NaAMPS; and one or more alkyl acrylates.

12. The ion-sensitive polymer as claimed in clause 11, characterized in that the polymer is formed of four monomers: acrylic acid, AMPS or NaAMPS, butyl acrylate and 2-ethylhexyl acrylate.

13. The ion-sensitive polymer as claimed in clause 12, characterized in that the polymer comprises from about 50 to less than 67% mol of acrylic acid, from more than 0 to about 10 mol% of AMPS or of NaAMPS; from about 15 to about 28 mol% butyl acrylate; and from about 7 to about 15 mol% of 2-ethylhexyl acrylate.

14. The ion-sensitive polymer as claimed in clause 13, characterized in that the polymer comprises from about 57 to less than 66 mol% acrylic acid, from more than 1 to about 6 mol% of AMPS or of NaAMPS; from about 15 to about 28 mol% butyl acrylate; and from about 7 to about 13 mol% of 2-ethylhexyl acrylate.

15. A binder composition for binding fibrous material to an integral fabric, said binder composition comprises the ion sensitive polymer as claimed in clause 1.

16. The non-woven fabric comprising a fibrous material and a binder material, characterized in that the binder material comprises a binder composition as claimed in clause 15.

17. An ion-sensitive polymer formed of four monomers: acrylic acid, AMPS or NaAMPS, butyl acrylate, and 2-ethylhexyl acrylate; wherein the polymer is insoluble in a neutral salt solution containing at least about 0.3% by weight of salt, said salt comprising one or more monovalent or multivalent ions; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 500 parts per million of one or more multivalent ions.

18. The ion-sensitive polymer as claimed in clause 17, characterized in that the polymer comprises from about 50 to less than 67% mol of acrylic acid, from more than 0 to about 10 mol% of AMPS or of NaAMPS; from about 15 to about 28 mol% butyl acrylate; and from about 7 to about 15 mol% of 2-ethylhexyl acrylate.

19. The ion-sensitive polymer as claimed in clause 18, characterized in that the polymer comprises from from about 57 to less than 66 mol% acrylic acid, from from more than 1 to about 6 mol% of AMPS or from NaAMPS; from about 15 to about 28 mol% butyl acrylate; and from about 7 to about 13 mol% of 2-ethylhexyl acrylate.

20. A binder composition for binding fibrous material into an integral fabric, said binder composition comprises the ion sensitive polymer as claimed in clause 17.

21. The non-woven fabric comprising a fibrous material and a binder material, characterized in that the binder material comprises a binder composition as claimed in clause 20.

22. A method for making an ion sensitive polymer characterized in that the method comprises: forming a hydrophilically / hydrifugically balanced mixture of two or more monomers, wherein at least one monomer contains one or more hydrophilic moieties, and at least one monomer contains one or more hydrophobic moieties; and polymerize the mixture; wherein the polymer is soluble in a neutral salt solution containing at least about 0.3% by weight of salt, said salt comprising one or more monovalent or multivalent ions; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 500 parts per million of one or more multivalent ions.

23. The method as claimed in clause 22, characterized in that the polymer is formed of one or more monomers selected from styrenesulfonic acid (SS), sodium salt of styrene sulfonic acid (NaSS), 2-acrylamido-2-methyl-1 propanesulfonic acid (AMPS), sodium salt of 2-acrylamido-2-methyl-l-propanesulfonic acid (NaAMPS), vinyl sulfonic acid, sodium salt of vinylsulfonic acid, or combinations thereof.

24. The method as claimed in clause 22, characterized in that the polymer comprises: acrylic acid, methacrylic acid, or a combination thereof, AMPS or NaAMPS; and one or more alkyl acrylates.

25. The method as claimed in clause 24, characterized in that the polymer is formed of four monomers: acrylic acid, AMPS or NaAMPS, butyl acrylate and 2-ethylhexyl acrylate.

26. A fibrous substrate comprising: a fibrous material; Y a binder composition for binding said fibrous material into an integral fabric, said binder composition comprises an ion-sensitive polymer wherein the polymer is insoluble in a neutral salt solution containing at least about 0.3% by weight of salt, said salt comprises one or more monovalent or multivalent ions; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 500 parts per million of one or more multivalent ions.

27. The fibrous substrate as claimed in clause 26, characterized in that the polymer is insoluble in the neutral salt solution containing at least about 0.3% by weight of salt, said salt comprising one or more monovalent or multivalent ions; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 200 parts per million of one or more multivalent ions.

28. The fibrous substrate as claimed in clause 27, characterized in that the polymer is insoluble in the neutral salt solution containing at least about 0.3% by weight of salt, said salt comprising one or more monovalent or multivalent ions; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 100 parts per million of one or more multivalent ions.

29. The fibrous substrate as claimed in clause 27, characterized in that the polymer is insoluble in a neutral salt solution containing at least about 0.3% by weight of salt, said salt comprising one or more monovalent or multivalent ions; and wherein the polymer is soluble in tap water containing from about 15 parts per million to about 50 parts per million of one or more multivalent ions.

30. The fibrous substrate as claimed in clause 26, characterized in that the polymer is insoluble in a neutral salt solution containing from about 0.5% by weight to about 5.0% by weight of the salt.

31. The fibrous substrate as claimed in clause 30, characterized in that the polymer is insoluble in a neutral salt solution containing from about 0. 5% by weight to about 3.0% by weight of the salt.

32. A water dispersible article comprising the fibrous substrate as claimed in clause 26.

33. The water dispersible article as claimed in clause 32, characterized in that the water dispersible article comprises a side-to-body liner, a fluid distribution material, a fluid intake material, an absorbent envelope sheet, a cover supply, or a damp cleaning cloth.

34. A wet cleaning cloth comprising the fibrous substrate as claimed in clause 26. ñ 61? R E S U E N The present invention is directed to ion-sensitive hard water dispersible polymers. The present invention is also directed to a method for making ion dispersible water-resistant polymers and their applicability as binder compositions. The present invention is further directed to fabrics containing fibers and fabrics comprising water-dispersible binder compositions sensitive to the ion and to its applicability in water-dispersible personal care products.