MXPA01006600A - Ion-trigger polymer coatings on water-sensitive polymer films - Google Patents

Abstract

The present invention provides a composition comprising an ion-trigger polymer coating joined to a water-sensitive substrate. When the composition is employed as a diaper outercover or a pantiliner baffle, for example, the ion-trigger coating is oriented toward the body and is exposed to bodily fluids. The coating inhibits the transport of the fluids to the inner, body-side water-sensitive substrate, maintaining the structural integrity of the composition. When the entire article is disposed of in a large volume of water, such as in the hydraulic flow of a toilet, both the water-sensitive substrate layer and the ion-trigger polymer coating layer mechanically weaken and break apart into small pieces.

Description

POLYMER COATINGS DISTRIBUTED BY ION ON POLYMER FILMS SENSITIVE TO WATER CROSS REFERENCE TO A RELATED APPLICATION This application claims the priority of the provisional patent application of the United States of America series No. 60 / 114,213 filed on December 29, 1998.

FIELD OF THE INVENTION The present invention relates to polymer compositions that are stable in water on a surface and sensitive to water on the opposite surface. More particularly, the present invention encompasses disposable water discharge barrier films that retain their integrity in the presence of body waste fluids but that disintegrate and disperse in the hydraulic flow of a toilet.

BACKGROUND OF THE INVENTION Disposable garments have revolutionized the modern lifestyle and are of great convenience for society. Such products are generally cheap, sanitary and fast and easy to use. The disposal of such products, however, is increasingly a problem when the landfills are closed and contribute to incineration and urban smoke. Consequently, there is an urgent need for disposable products that can be discarded without being thrown into a landfill or disposed of by incineration. An ideal disposal alternative would be the use of municipal sewer treatment and private residential septic systems. Suitable products to be disposed of in sewer systems that can be discharged with water discharge in a conventional toilet are called "disposable with water discharge". An essential characteristic of disposable products with water discharge is that they must have sufficient strength for the intended use, but that they will nevertheless lose their structural integrity in contact with water. Meeting this double standard is particularly difficult for products that come into contact with body waste fluids, especially urine.

Numerous attempts have been made to produce disposable fibers, fabrics, films and adhesives with water discharge that retain their integrity and resistance to moisture in the presence of waste fluids from the body, but which nonetheless are discarded through the discharge of water in conventional toilets. One approach to producing a disposable product with water discharge is to limit the size of the product so that it can easily pass through the pipe without causing obstructions or blockages. Such products can have a high resistance to wetting and will not disintegrate during disposal with water discharge. Examples of this type of product may include cleaning cloths such as baby wipes. This approach to waste with water discharge suffers the disadvantage, however, of being restricted to small items. Many of the disposable products are currently limited to such small items.

Another approach to producing a disposable product with water discharge is to produce a product that is normally insoluble in water, but which disintegrates in the presence of aqueous alkaline or acidic solutions. The end user is provided with an alkaline or acidic material to add to the water in which the product will be discarded. This approach allows disposal through the normal piping systems of products substantially larger than the cleaning cloths, but suffers from the disadvantage of requiring the user to carry out the step of adding the chemical solvent to the water. A further disadvantage is that inadvertent or unintentional disposal of such a product in a conventional toilet without the addition of the chemical solvent can cause a blockage or serious obstruction of the pipe system. This latter disadvantage can, however, be overcome by incorporating the solvent acid or alkali into the article, but separated from the dissolvable material while in use. The chemical solvent is only released on contact with water during the discharge with water discharge.

Similarly, another approach to producing a disposable product with water discharge, consists of forming the product of a pH-sensitive polymer, and storing the product in the presence of a separate solution of acidic pH. When the product is placed in a large amount of water from the normal tap, it disintegrates as a result of the pH change. A disadvantage of this approach to pH change for waste with water discharge is that some acidic polymers lose resistance to wetting at a slightly alkaline pH in the range of 7-8. Because the pH of the urine can be as high as 8.5, these disposable materials may not be very suitable for use in, for example, diapers or incontinence pads.

Yet another approach to producing a disposable product with water discharge is to form the product of a material that is susceptible to attack by specific enzyme catalysis that breaks the structural integrity of the material. In such a product the enzymes can be introduced into the waste water separately. These systems suffer from many of the same problems as the materials treatable with acid or alkaline.

Still others have attempted to make disposable products with water discharge where a non-woven fabric is joined together with salt-sensitive binders. For example, some acrylic copolymers are precipitated in the presence of high concentrations of calcium ions. The problem with water-soluble binders that depend on calcium, however, is that throughout the country the calcium concentration in the tap water varies tremendously. Consequently, disposable products with water discharge made with those binders may not be disposable with de-watering in fact in regions with water of high calcium content.

None of the approaches mentioned above have proven to be completely satisfactory. Therefore, there is a need for a disposable barrier product with water discharge which is stable in the body fluids containing ion, and which does not require special disposal conditions.

SYNTHESIS OF THE INVENTION The present invention provides a composition comprising a coating of ion-releasing polymer bound to a water-sensitive substrate. When the composition is employed as an outer diaper cover or a pant liner, for example, the ion release coating from side to body and interior is exposed to body fluids and acts as a barrier coating thus inhibiting its transport to the lower water sensitive substrate, maintaining the structural integrity of the composition. When the entire article is discarded in a large volume of water, such as the hydraulic flow of a toilet, both the water-sensitive substrate layer and the ion-trigger polymer coating layer are mechanically weakened and rupture and separate.

The present invention is therefore desirably designed to provide disposable compositions that can be cleaned with water discharge in a conventional toilet. It is also desirable to provide disposable compositions that act as barriers to the fluid, but which are capable of being discharged by discharging water into a conventional toilet without the addition of a chemical solvent. Additionally, it is desirable to provide disposable compositions with water discharge that are insoluble in the presence of body waste fluids, but which are dispersible in water in the presence of normal toilet water. Also, it is desirable to provide disposable compositions with water discharge that disintegrate and disperse in the water of the normal toilet regardless of geographical variations in the salt concentrations of the toilet water. Additionally, it is desirable to provide disposable compositions with water discharge that have sufficient strength for their intended use. Finally, it is desirable to provide disposable products with water discharge, including but not limited to women's care products, diapers and training underpants, to bandages, to packaging, to release films and similar.

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a composition comprising a coating of ion-releasing polymer bound to a water-sensitive substrate. When the composition is employed as an outer diaper cover or a pant liner, for example, the inner ion release coating is exposed to body fluids, and acts as a barrier coating, thereby inhibiting its transport to the body. lower water sensitive substrate, maintaining the structural integrity of the composition. When the composition is discarded in a large volume of water, such as the hydraulic flow of a toilet, both the water-sensitive substrate layer and the ion-trigger polymer coating layer are mechanically weakened and rupture and separate.

Thus, an embodiment of the present invention provides a composite two-layer article comprising an ion-releasing coating on a water-sensitive substrate. In normal use, it is understood that the coated side of the inner ion trigger of the article will typically be exposed to body fluids such as blood, menstrual fluid, vaginal exudate, urine and perspiration. The term "inner side" as used herein means the side of the film closest to the user's skin. Both the inner ion trigger coating and the external water sensitive substrate will be exposed to the toilet water during disposal. The ion-release coating on the inner side acts as a barrier coating and inhibits the transport of body fluids from the wearer through the article directly providing a barrier between the body fluids and the water-sensitive substrate.

In a further embodiment of the present invention, the composition can serve as a primer layer for additional coatings on the water sensitive substrate, such as latex coatings or as a second layer of an ion release material. The primer layer provides sufficient water protection so that the water-based solution coating can be applied to the coated water-sensitive film, the water being subsequently removed before any degradation of the water-sensitive substrate layer. In most cases and applications, the coated water-sensitive film is disposable with water discharge and dispersible because it will disintegrate rapidly when exposed to water flow such as in a conventional toilet.

Disposable articles with water discharge of the present invention can be made completely from disposable components with water discharge, or be composed of a mixture of disposable materials with discharge of water and non-disposable with discharge of water. In the first case, the entire article disintegrates or disperses in the water flow of the normal toilet water, whereas in the latter case, the disposable components with water discharge disperse in the presence of the normal toilet water. The disposable article with water discharge is separated into pieces small enough to be discarded with water discharge without causing an obstruction.

The term "disposable with water discharge" as used herein, means being able to be discharged with discharge of water into a conventional toilet and being introduced into a residential septic or municipal sewer system, without causing an obstruction or blockage in the septic system. the toilet or sewer system; and does not adversely affect the microbiology of the septic or sewer treatment system. The term "disposable item with water discharge" as used herein includes, but is not limited to, women's care products, diapers and training underpants, bandages, packings, release films, and the like.

Various formulas of the ion-trigger polymer coating can be used with the present invention. In order to be effective for use in disposable personal care products with water discharge, the ion release coating must be functional in use, for example, maintain integrity and act as a barrier in the presence of body fluids but dissolve or disperse rapidly in the water found in the toilets. The main component of the ion-trigger coating of the present invention is an ion-trigger polymer. An ion-releasing polymer is one whose strength and dispersibility in water is changed depending on a very slight difference in salt concentrations. More specifically, an ion-releasing polymer loses strength and disperses in tap water, but maintains the strength and is insoluble in an aqueous solution which contains not less than 0.5% by weight of a neutral inorganic salt comprising a monovalent ion such as NaCl, Kcl and NaBr.

It is well known that the addition of an inorganic salt to an aqueous solution of a water-soluble polymer can force precipitation of the polymer through a desalting phenomenon. For example, anionic polymers, such as sodium salts of polyacrylate and carboxymethyl cellulose, are rendered insoluble in an aqueous solution of common salt having a concentration of 4 to 5%, or higher. Nonionic polymers such as hydroxyethyl cellulose and polyvinyl alcohol (PVA) are insoluble in an aqueous solution only when the concentration of the ion salt is increased to about 10% or higher. This desalting of a water-soluble polymer describes the change from a homogeneous polymer solution to a polymer precipitate.

Even though an ion-releasing polymer is indeed salt-sensitive as the simple water-soluble polymers mentioned above, there are several significant differences in the behavior of an ion-releasing polymer for the disposable applications with water discharge. First the ion trigger polymer can be sensitive to changes in an ion concentration at low levels, such as 0.5% by weight of a common salt. Secondly, in the aqueous ionic solutions of typical body fluids, the ion-releasing polymer is expected to be not only insoluble, but also requires maintaining integrity and strength and acting as a barrier coating. Finally, the ion-releasing polymer loses sufficient strength or integrity by dispersing in tap water; but note that dispersion does not necessarily require complete dissolution, as would be typical with simple salt-soluble water-soluble polymers.

The integrity and wear resistance characteristic can be achieved by ensuring an adequate "hydrophobic / hydrophilic balance" through the polymer chain As used herein, the term "hydrophobic / hydrophilic balance" refers to a balance of halves hydrophobic and hydrophilic along the polymer chain, which results in the polymer having a desired firing property. By controlling the hydrophobic / hydrophilic balance in the polymer composition, ion-sensitive polymers having an integrity in use and water dispersibility desired are produced. In contrast, for simple salt-soluble water-soluble homopolymers, such as polyvinyl alcohol, the hydrophobic / hydrophilic character is fixed by the monomer structure and can not be adjusted.

In an ion release coating formula, the ion trigger character is provided by a sulfonated polyester condensation polymer. The hydrophobic / hydrophilic balance can be controlled by the choice of the monomers involved in the condensation reaction. The preparation of such polyesters is generally described, for example, in U.S. Patent Nos. 4,910,292, 4,973,656 and 4,990,593 and in European Patent Application No. EP 0 761 795 A2, all incorporated herein by reference.

In general, the ion-releasing material is a material that acts as a barrier coating which thus inhibits the transport of fluids through coating. Preferably, these materials are melt processable since they are easier to apply to a water soluble substrate. Several different aqueous compounds have ion shot, however, these compounds are not preferred. For example, U.S. Patent Nos. 5,317,063 and 5,312,883 disclose copolymers of acrylic acid or methacrylic acid that are ion sensitive. Unfortunately, these materials are not melt processable and are not amenable to molten coating. Coating an aqueous solution of ion trickling polymers on a water sensitive substrate is difficult since the aqueous nature of those coatings tends to partially dissolve the water soluble substrate. In addition, the acrylic or methacrylic functionality in the polymer is sensitive to physical cross-linking through divalent ions and therefore does not readily disperse in hard water.

In a desired embodiment of the invention, the ion-trigger polymer coating composition includes at least one water-dispersible copolyester, present in an amount of from about 25 to 100% by weight. Water-dispersible copolyesters are those in which the ionic moieties or water-sensitive reactants are incorporated in the column.

Alternatively, the ion moieties can be grafted onto the column. The structure of such copolyesters is described by Miller et al. In WO 95/18191, incorporated herein by reference. The "Eastman AQ" copolyesters, as taught by Miller, incorporate ionic moieties by copolymerizing 5-sodiosulfoisophthalate units on a polyester column. Due to certain deficiencies in the pure polymer, it is often desirable to add a second compatible polymer at a concentration of up to about 20% by weight to increase cohesive strength, improve spraying and / or reduce cold flow tendencies. This second polymer can be any compatible elastomer such as the thermoplastic block copolymer, an amorphous or crystalline polyolefin such as polypropylene, polybutylene or polyethylene; and ethylenic copolymers such as ethylene-vinyl acetate, ethylene-methyl acetate and mixtures thereof.

Other useful ion-releasing polymers are described in U.S. Patent Nos. 5,543,448 and 5,552,495 incorporated herein by reference, which describe the sulfonated copolyesters. Other useful polymer blends are available from National Starch and Chemical Company as NS70-4395 or NS70-4442.

In addition to the sulfonated copolyesters mentioned above, a variety of trigger polymers are known in the art. U.S. Patent No. 5,770,528 discloses methylated hydroxypropyl cellulose as a polymer with a trigger controlled by temperature and ion concentration. The hydroxypropyl cellulose itself has some sensitivity to the ion, but it is more of a trigger material per temperature. Indeed, U.S. Patent No. 5,509,913 lists a variety of polymers, including polyvinyl methyl ether, polyvinyl alcohol and various cellulose polymers with temperature triggers modulated by ion concentration. Although these temperature triggering polymers may have some utility in the ion release coating, these simple polymers by themselves usually do not have the proper "hydrophobic / hydrophilic" balance to provide the integrity and strength required in use.

In general, the thickness of the ion-firming coating layer will depend on the product to be made, preferably, the thickness is between about 0.1 to 3.0 mils. More preferably, the thickness is between about 0.5 to 2.0 thousandths of an inch. More preferably, the thickness is about 0.8 mils.

It may also be desirable to incorporate up to 20% by weight of certain other non-crystalline hydrophilic polymers in the ion-firing layer such as hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl methyl ether, polyvinyl pyrrolidone, polyethoxyloxazoline, such as cellulose esters, particularly acetates. with a degree of substitution of less than 2.5; the latter polymers function to increase the water sensitivity of the ion trigger coating layer, which may be desired for some applications.

It may also be advantageous to mix the ion-releasing polymer coating composition with a hydrophobic polymer, such as polypropylene, polyethylene, or poly (lactic acid). The hydrophobic polymer can alter both the sensitivity of the ion-firing composition to the differences between the salt solution and pure water, and the time to a barrier failure when the composition is exposed to either the salt solution or the salt solution. pure water.

Other compatible hydrophobic polymers include elastomeric polymers such as block copolymers containing styrene, for example, styrene-isoprene-styrene, epoxidized polyisoprene, styrene-butadiene-styrene, styrene-ethylene butylene-styrene, styrene-ethylene propylene styrene can also be present at levels of up to about 30% by weight. Of these polymers, those based on styrene-isoprene-styrene are most preferred. Among the applicable stabilizers or antioxidants which may be included here are the high molecular weight hindered phenols and the multifunctional phenols such as sulfur and phosphorus-containing phenols. Representative locked phenols include: 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxyphenyl) propionate; n-octadecyl 3, 5-di-tert-butyl-4-hydroxyphenyl) propionate; 4, 4'-methylenebis (2,6-di-tert-butylphenol); 4,4'-thiobis (6-tert-butyl-o-cresol); 2,6-di-tert-butylphenol; 6- (4-hydroxyphenoxy) -2,4-bis (n-octylthio) -1,3,5-triazine; di-n-octadecyl-3, 5-di-tert-butyl-4-hydroxybenzyl phosphonate; 2 - (n-octylthio) -ethyl 3,5-di-tert-butyl-4-hydroxybenzoate; and sorbitol hexa (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate). If used, the stabilizer may be present at levels of 0.1 to 3% by weight.

A plasticizer is broadly defined as a typically organic composition that can be added to thermoplastics, rubbers and other resins to improve extrusion, flexibility, workability or stretch. The plasticizers can be used in the ion firing layer at concentrations of up to about 50% by weight. Preferably, the plasticizing agent is a solid at room temperature with a softening point above 60 degrees Celsius, and belongs to the class of plasticizers including cyclohexane dimethanol dibenzoate. Any plasticizer that will recrystallize from the combined thermoplastic composition is suitable, for example, a 1,4-cyclohexane dimethanol dibenzoate compound commercially available from Velsicol Chemical Corporation, of Rosemont, Illinois, under the trademark BENZOFLEX® 352. Other plasticizers that can suitable for this purpose are described in European patents EP 0422 108 Bl and EP 0 410 412 Bl, both assigned to HB Fuller Company, incorporated herein by reference. When combined with copolyesters, such as the Eastman AQ series, these plasticizers exhibit the unique ability to roughly improve processing in the molten state, but without interfering with the assortment once they have cooled and solidified.

Other suitable plasticizers include hydrocarbon agents, polybutene, liquid glutinizing resins, and liquid elastomers. Such oils are primarily hydrocarbon oils, and are paraffinic or naphthenic in nature. The oils are preferably low in volatility, transparent and have as little color and smell as possible. The use of the plasticizers in this invention also contemplates the use of olefin oligomers, low molecular weight polymers, vegetable oils and their derivatives and similar plasticizing liquids.

The ion trigger coating layer may comprise a wax present in amounts of up to 20% by weight, more preferably in amounts ranging from about 1 to about 10% by weight. The wax is added to modify the viscosity, reduce the stickiness, and improve the resistance to moisture. In one embodiment, the wax is polar in nature such as amide waxes. Other useful waxes include paraffin waxes, microcrystalline waxes, Fischer-Tropsch synthesis products, polyethylene and polyethylene by-products.

As is known in the art, various other components can be added to modify the stickiness, color, and odor of a polymer. It is generally preferred that the other components or ingredients should be relatively inert and have negligible effects on the properties contributed by the copolyester, the glutinizing agent and the plasticizer. Antioxidants and other stabilizing ingredients can also be added to protect the ion-releasing polymer from various heat and light induced degradations, but are not essential to the compositions of this invention.

The optional additives can be incorporated into the ion-trigger polymer coating composition in order to modify certain properties thereof. Among these additives are dyes such as titanium dioxide, and fillers such as talc, clay or other silicates.

For a disposable composition with a water discharge of the present invention, such as an outer diaper cover or a pant liner, the inner side of the composition, the side closest to the wearer of the article, will typically be exposed to the body fluids in use, while both sides will be exposed to toilet water in the waste. The ion-releasing coating on the side adjacent to the article user inhibits the transport of body fluids through the composition and provides a barrier between the body fluids and the water dispersible substrate on the other surface. However, the side of the article further away from the user of the water dispersible substrate is designed to rapidly weaken in the water flow of the toilet, and allows the complete composition to lose sufficient structural integrity to be discarded with discharge of water into a container. conventional toilet. Preferably, the wet substrate has a peak load resistance of less than 20 g / inch, which is comparable to a wet bathroom tissue.

Polymers suitable for the water-sensitive substrate layer include, but are not limited to, polyalkylene oxides, such as polyethylene oxide (PEO), ethylene oxide-propylene oxide copolymers, polymethacrylic acid, copolymers of polymethacrylic acid, polyvinyl alcohol and copolymers of vinyl alcohol, polyethyl oxazoline, polyvinyl methyl ether, polyvinyl pyrrolidone / vinyl acetate copolymers, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose , ethyl hydroxyethyl cellulose, methyl ether starch, poly (n-isopropyl acrylamide), poly N-vinyl caprolactam, polyvinyl oxazolidone, polyvinyl oxazolidimone, poly (2-isopropyl-2-oxazoline), poly (isopropyl oxazoline), and poly (2,4-dimethyl-6-triazinyl ethylene). The water-sensitive substrate layer of the present invention can be made completely from water-sensitive polymeric material or it can contain water-sensitive as well as water-insoluble materials as long as the film is dispersed in the water, such as in the hydraulic flow of a water. conventional toilet. Additionally, the water-sensitive substrate can also be made by mixing several different types of water-sensitive film materials. In some embodiments, it may be desirable to employ one or more additives in the water-sensitive substrate layer material, including, but not limited to, compatibilizers, processing aids, plasticizers, glutinizers, debonders. , to the slipping agents, and to the antimicrobial agents, as manufacturing agents or as modifiers depending on the specific properties desired in the water-sensitive substrate and in the final product.

Desirably, the water sensitive substrate of the present invention comprises a polyalkylene oxide film or a polyvinyl alcohol film. More desirably, the water-sensitive substrate of the present invention comprises a polyethylene oxide film, a polypropylene oxide-ethylene oxide copolymer film, a polyvinyl alcohol film, or a film derived from a polyvinyl alcohol copolymer. More desirably, the water-sensitive substrate of the present invention comprises a polyethylene oxide film or a polyvinyl alcohol film. The thickness of the water sensitive substrate can vary greatly depending on the final use of the product containing the film. The thickness of the water-sensitive substrate should be minimized where possible to reduce the cost of the product and to reduce the time necessary for the substrate to disperse, especially in the case of disposable products with water discharge. Desirably, the thickness of the water-sensitive substrate should be as thin as possible, depending on the product to be made. Preferably, the thickness will be from about 0.1 to 3.0 mils.

In the uncoated form, when the water sensitive substrate contacts water on any surface, it disperses. In the ion-coated coated form, when only the outer side of the water-sensitive substrate makes contact with water, the composite two-layer structure will not disperse immediately, due to the transient structure integrity of the ion-releasing coating. However, the composite two-layer composition is dispersible when both the ion-releasing coating and the water-sensitive substrate have been exposed to water for some time.

The coating of the ion-releasing polymer provides the required barrier to the fluids of the ion-containing body, but weakens and disperses in the toilet water containing a relatively low ion. In the presence of an aqueous salt solution, such as urine, the ion-releasing polymer is relatively inert. The water in the salt solution can reach the substrate only by a slow diffusion process through the coating. However, the ion-releasing polymer weakens rapidly in tap water. The process of water penetration into the coating will differ with the ion content of the aqueous solution.

The ion-releasing layer can be attached to the water-dispersible substrate by standard methods known to those of ordinary skill in the art. As mentioned, the ion-firing layer itself can provide enough tack to join the water-sensitive substrate layer thereto. Other suitable methods of joining the layers include, but are not limited to, the solvent-based coating and the hot melt coating. Suitable solvent-based coating techniques include, but are not limited to, spray coating and ink jet printing. Suitable hot-melt coating techniques include, but are not limited to, slotted coating, grid coating, spray coating, swirl coating, and gravure coating. Another suitable method includes a coating transfer process.

The preferred coating process is a hot melt groove die process. The melted ion trigger polymer is delivered from a melt tank through a heated hose to a slot die. The temperature of the melt tank, the hose and the slot die may vary depending on the rheology of the melt of the ion trigger in the coating process. The molten polymer is applied uniformly directly on the water sensitive film, or alternatively on a carrier substrate and subsequently transferred to the water sensitive film (transfer coating process). Line speeds may vary depending on the "open time" of the ion trigger. As used herein, the "open time" of the polymer refers to the amount of time required for the polymer to lose its tackiness.

The polyethylene oxide film is the most desirable film for a transfer coating process, while the polyvinyl alcohol film is the most desirable film for a direct coating process.

In a transfer coating process, the coated carrier substrate is further moved through the process and brought into contact with the water-sensitive film, which is suitably aligned with the coated carrier substrate. The coating is transferred from the carrier substrate to the water-sensitive film under pressure as the film and the carrier substrate pass through a pressure point roller. In practice, the optimum coating thickness was achieved by adjusting the processing factors which include, but are not limited to, the coating temperature, the resin flow rate, the line speed and the applied pressure. on the pressure point roller.

In the transfer coating process or in the direct contact coating process, such as grid printing, the adhesion of the ion-releasing coating to the water-sensitive film must be greater than the adhesion of the ion-release coating to the grid (direct contact) or to the carrier substrate (transfer coating). The choice of the ion trigger must take into consideration the desired characteristics and properties of the ion trigger. The ion trigger must have good adhesion to the water-sensitive substrate.

Those skilled in the art will readily understand that the water dispersible films coated with ion scaler of the present invention will be advantageously employed in the preparation of a wide variety of products designed to make contact with aqueous fluids. Although the coated water dispersible film of the present invention is particularly suitable for personal care products, the coated water dispersible film of the present invention can be advantageously employed in the preparation of a wide variety of different consumer products. to personal care products.

EXAMPLES Example 1 A two-layer composite structure was produced by coating an ion-firing mixture from National Starch and Chemical Company (of Bridgewater, New Jersey) coded resin NS70-4395 on a polyethylene oxide film made of mixed resin and pelletized by Planet Polimer Technologies, Inc. (of San Diego, California). The mixture was characterized in terms of its melt viscosity, as measured on a capillary rheometer (Gottfeld Rheograph 2003, from Gotthard Werkstoff-Prüfmaschinen GmbH, Buchen, Germany). The viscosity data are reported in Table 1. As has been appropriate for the coating application, this material was classified as a moderate or low viscosity fluid at the application temperature of about 150 ° C. The coating was applied with a precision slot matrix coater from Acumeter Laboratories Inc., to an AKROSIL® release paper (Akrosil, Menasha, Wisconsin) and then transferred to the polyethylene oxide substrate. Coated films were prepared with 0.5, 1.0, 1.5, and 2.0 thousandths of ion trigger coating thicknesses.

The barrier properties of these films were then tested in a laboratory with a modified Cobb test. In the standard Cobb test for taking water in a film (American Society for Testing and Materials [Philadelphia, Pennsylvania] D3285, Technical Association of the Pulp and Paper Industry T441), a fixed surface area of the film, held under a steel ring, is kept under a pond of water, which is 1 centimeter deep, for a fixed time. The weight gain in the film due to the absorption of water, from the initial dry state to the dried state with final blotting paper, was measured. In these experiments, the test was modified from a weight gain method to a visual indicator test by introducing a pH paper layer (Hydrion paper for a pH range of 3.5 to 5.5, from Hydrion Papers, Inc. [ Brooklyn, New York 11210]) below the film. The pH paper turns from orange to green-green / blue when exposed to water and salt water solution; the pH paper changes color in the same way when exposed to a wetted polyethylene oxide film that lies on top of it. The color change gives a visual indication of the time at which the water permeated through the barrier coating and then wetted the polyethylene oxide substrate.

The time for the water to permeate through the coated film was monitored as a function of the thickness of the film and the type of fluid. Two fluids were used: distilled water as an imitation of toilet water and a two percent sodium sulfate solution as an imitation of urine. In the distilled water, all coatings failed under one minute, as indicated by a change in color of pH paper from orange to blue green. In the salt r solution, the time for r permeation depended on the thickness of the film. The 2.0 mil ion release coating provided protection for over 30 minutes on average, since the color of the pH paper did not change. The thinner coating protected against r runoff only for less than 1 minute. The experiments indicated that, even in the salt r solution, the trigger coating is hydrated by r. In the salt r solution, the release coating is hydrated by r. In the salt r solution, hydration is a slow process and seems to be of controlled diffusion. The level of barrier protection against the salt solution can be controlled (up to a time of 30 minutes) by the thickness of the film.

As a measure of the dispersibility of the films, their resistance to wetting was also tested. A 1-inch by 4-inch film sample was gripped by the short sides in a Vitrodyne V-1000 mini-tension tester from Chattilon (of Greensboro, North Carolina) and then submerged, with all handles, in a beaker fluid. The fluid comprised either distilled water or a salt solution. After 30 seconds, the sample was pulled and separated and the peak load was measured. The peak load in the distilled water was essentially less than the resistance in the salt solution. In the distilled water, the strength of a 2.0 mil coating was slightly higher than that of the wet toilet tissue, while the strength of a 1.0 mil coating was less than that of the toilet floss. These data indicate that when moistened in the toilet water, the coated film must break sufficiently to disperse.

Example 2 A higher melt viscosity version of a National Starch trigger mixture, encoded NS70-4442 and co-extruded with poly (ethylene oxide) was obtained. The viscosity characteristics of this resin, which were again measured on a capillary rheometer (from Gottfeld Rheofraph 2003, from Gotthard Werkstoff Prüfmaschinen GmBH, Buchen, Germany) are reported in Table 1. As is appropriate for a coextruded application, the The viscosity of NS770-4442 was appreciably higher than for NS70-4395 of Example 1. The film contained poly (ethylene oxide) made from resin blended and pelletized by Planet Polymer Technologies Inc. (of San Diego, California 92131). In the two-layer structure, the shot resin formed a thin coating, with a nominal thickness of 0.4 mils. The barrier performance of this coextruded coating was consistent with the coatings of a slot matrix. Even when the water penetration was essentially instantaneous, the salt solution was kept outside the polyethylene oxide substrate for about 1 minute. At the same time, the resistance to wetting in both the water and the salt solution was higher than that found in the groove coating of 1.0 thousandths of an inch (and higher than in that of the toilet tissue). These results were obtained by using a 1-inch by 4-inch film sample that was grabbed by the short sides in a Vitrodyne-1000 mini-tension tester and then immersed with handles and all, in a beaker of fluid. The fluid comprised either distilled water or a salt solution. After 30 seconds, the sample was pulled and separated and the peak load was measured.

Table 1 It will be understood that the incorporations described above are merely illustrative and are not intended to limit the scope of the invention. On the contrary other incorporations will be obvious to one with skill in the art in light of the description of the present invention and all those obvious variations are contemplated as being within the scope of the appended claims.

Claims (25)

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

1. A disposable film with water discharge comprising a molten ion-trigger polymer coating and processable on a water-sensitive substrate layer.

2. The disposable film with water discharge as claimed in clause 1, characterized in that the water-sensitive substrate layer is composed of a polymer selected from polyalkylene oxides, such as polyethylene oxide or ethylene oxide copolymers. propylene oxide, polymethacrylic acid, copolymers of polymethacrylic acid, polyvinyl alcohol, copolymers of polyvinyl alcohol, polyethyl oxazoline, polyvinyl methyl ether, polyvinyl pyrrolidone / vinyl acetate copolymers, methyl cellulose, ethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, ethyl hydroxyethyl cellulose, methyl ether starch, poly (n-isopropyl acrylamide), poly N-vinyl caprolactam, polyvinyl methyl oxazolidone, polyvinyl methyl oxizolidimone, poly (2-isopropyl-2-oxazoline), or poly (2,4-dimethyl-6) -triazinyl ethylene).

3. The disposable film with water discharge as claimed in clause 2, characterized in that the water-sensitive substrate layer comprises ethylene oxide.

4. The disposable film with water discharge as claimed in clause 1, characterized in that the coating of ion-releasing polymer is of a thickness of between 0.1 and 3.0 thousandths of an inch.

5. The disposable film with water discharge as claimed in clause 1, characterized in that the water-sensitive substrate layer is between 0.1 and 3.0 mils in thickness.

6. The disposable film with water discharge as claimed in clause 1, characterized in that the molten and processable ion trigger polymer is selected from copolyesters, copolyesters having an ionic half grafted thereto, sulfonated copolyesters, or methylated methylated hydroxypropyl cellulose .

7. The disposable film with water discharge as claimed in clause 1, characterized in that the ion-release polymer coating also comprises a non-crystalline hydrophilic polymer selected from hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl methyl ether, polyvinyl pyrrolidone, polyethyl oxazoline , starch, a cellulose ester, or a combination thereof.

8. The disposable film with water discharge as claimed in clause 7, characterized in that the non-crystalline hydrophilic polymer is added in an amount of from about 0 to about 20% by weight of the ion-releasing polymer.

9. The disposable water discharge film as claimed in clause 7, characterized in that the ion-release polymer coating further comprises a hydrophobic polymer selected from polypropylene, polyethylene, poly (lactic acid) or a styrene-containing block copolymer .

10. The disposable film with water discharge as claimed in clause 1, characterized in that the ion-release polymer coating further comprises a hydrophobic polymer selected from polypropylene, polyethylene, poly (lactic acid) or a styrene-containing block copolymer .

11. The disposable film with water discharge as claimed in clause 10, characterized in that the hydrophobic polymer is added in an amount of from about 0 to about 30% by weight of the ion-releasing polymer.

12. The disposable film with water discharge as claimed in clause 1, characterized in that the ion-release polymer coating also comprises a stabilizer and / or an antioxidant selected from the higher molecular weight bound phenols of sulfur-containing phenols. or of phenols that contain phosphorus.

13. The disposable film with water discharge as claimed in clause 1, characterized in that the coating of ion-releasing polymer comprises a plasticizer.

14. The disposable film with water discharge as claimed in clause 13, characterized in that the plasticizer is added in an amount of from about 0 to about 50% by weight of the ion-releasing polymer.

15. A disposable product with water discharge comprising: the disposable film with water discharge of clause 1; Y at least one additional layer adhered to the disposable film with water discharge.

16. The disposable product as claimed in clause 15, characterized in that the disposable product is selected from an article for personal care, an item for medical care, a packaging material or a release film.

17. A method for making a disposable film with water discharge comprising: forming a layer of a molten and processable ion trigger polymer on a water sensitive substrate layer.

18. The method as claimed in clause 17, characterized in that the molten and processable ion trigger polymer is formed on the water sensitive substrate layer by simultaneously generating the two layers in a coextrusion process.

19. The method as claimed in clause 17, characterized in that the fused and processable ion trigger polymer is formed on the water sensitive substrate layer by coating the melt processable ion trigger polymer on the water sensitive substrate.

20. The method as claimed in clause 19, characterized in that the molten and processable ion trigger polymer is coated using a coating process selected from a direct coating process or from a transfer coating process.

21. The method as claimed in clause 17, characterized in that the water-sensitive substrate layer is composed of a polymer selected from polyalkylene oxides, such as copolymers of polyethylene oxide or ethylene oxide-propylene oxide, polymethacrylic acid, polymethacrylic acid copolymers, vinyl alcohol, polyvinyl alcohol copolymers, polyether oxazoline, polyvinyl methyl ether, polyvinyl pyrrolidone / vinyl acetate copolymers, methyl cellulose ethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, ethyl hydroxyethyl cellulose, methyl starch poly (n-isopropyl acrylamide) ether, poly N-vinyl caprolactam, polyvinyl methyl oxazolidone, polyvinyl methyl oxazolidimone, poly (2-isopropyl-2-oxazoline) or poly (2,4-dimethyl-6-triazinyl ethylene).

22. The method as claimed in clause 21, characterized in that the water sensitive substrate layer comprises polyethylene oxide.

23. The method as claimed in clause 17, characterized in that the coating of ion-releasing polymer is of a thickness of between 0.1 and 3.0 thousandths of an inch.

24. The method as claimed in clause 17, characterized in that the water-sensitive substrate layer is of a thickness between 0.1 and 3.0 thousandths of an inch.

25. The method as claimed in clause 17, characterized in that the fused and processable ion trigger polymer is selected from copolyesters, copolyesters having an ionic half grafted thereto, sulfonated copolyesters or methylated hydroxypropyl cellulose. SUMMARY The present invention provides a composition comprising a coating of ion-releasing polymer bound to a water-sensitive substrate. When the composition is employed as an outer diaper cover or a pant liner, for example, the ion release coating faces the body and is exposed to body fluids. The coating inhibits the transport of the fluids to the water-sensitive substrate from the side to the inner body, maintaining the structural integrity of the composition. When the entire article is discarded in a large volume of water, such as in the hydraulic flow of a toilet, both the water-sensitive substrate layer and the ion-trigger polymer coating layer are mechanically weakened and break apart. in small pieces.