WO2007092290A2

WO2007092290A2 - Conductive articles including hot melt superabsorbent polymer composition and method of making and method of using the same

Info

Publication number: WO2007092290A2
Application number: PCT/US2007/002844
Authority: WO
Inventors: Sharf U. Ahmed; Eugene R . Simmons; Stephen G. Rippe
Original assignee: H.B. Fuller Licensing & Financing, Inc.
Priority date: 2006-02-02
Filing date: 2007-02-02
Publication date: 2007-08-16
Also published as: WO2007092290A3

Abstract

A conductive article that includes a hot melt superabsorbent polymer composition that includes thermoplastic polymer and superabsorbent polymer particles, and an electrical connector in electrical communication with the hot melt superabsorbent polymer composition.

Description

H.B. Fuller Company Docket No. DR-008- WO-Ol

CONDUCTIVE ARTICLES INCLUDING HOT MELT SUPERABSORBENT POLYMER COMPOSITION AND METHOD OFMAKING AND METHOD OF USING THE SAME

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Application Serial No. 60/765,344, filed on February 2, 2006, entitled, "Conductive Articles Including Hot Melt Superabsorbent Polymer Composition," and incorporated herein. BACKGROUND

The invention relates to electrically conductive articles. A variety of electrical conducting articles are used in medicine to monitor a patient's condition, especially in electrocardiography and electroencephalography. In electrocardiography, for example, pads containing conductive material are attached to the trunk and limbs of a patient's body by way of an adhesive. Electrodes are then connected to the conductive material, and to an electrocardiograph by way of cables. The electrocardiograph receives a signal transmitted from the body and through the cables, processes the signal, and outputs the resulting information typically to a monitor and a strip of moving paper. While the patient is being monitored, it is important to prevent or impede the transmission of "electrical noise." Electrical noise results in misinformation that can substantially change the accuracy of the output of the electrocardiograph. Air gaps, which are nonconductive, between the patient's skin and the electrode are one such cause of "electrical noise." In order to achieve uniform intimate contact between the electrode and the skin, often a jelly or cream is applied to the area of the electrode that is to come in contact with the patient's skin, which eliminates the nonconductive air gaps between the patient's skin and the electrode. After the electrode is removed, however, the jellies and creams tend to leave a messy residue on the hand of the technician and on the skin of the patient. A soap or solvent is required to remove the residue from the technician, patient, and electrode. Therefore, there is a need for a conductive pad that provides a intimate, conductive, and conformable interface between the patient's skin and the electrodes placed thereon, and that requires little to no cleanup after use. SUMMARY

In one aspect, the invention features a conductive article (e.g., an electrocardiogram pad) that includes a fibrous layer, a hot melt superabsorbent polymer composition, and a pressure sensitive adhesive composition disposed on the fibrous layer. In another embodiment, the conductive article includes a conductor.

In one embodiment, the conductive article includes a skin contacting layer, the hot melt superabsorbent polymer composition being disposed between the skin contacting layer and the fibrous layer.

In one embodiment, the conductive article includes a liquid impermeable layer disposed between the fibrous layer and the hot melt superabsorbent polymer composition. In another embodiment, the conductive article includes a liquid permeable, superabsorbent polymer particle impermeable barrier layer.

In one aspect, the invention features a method of using a conductive article that includes hot melt superabsorbent polymer composition, a fibrous layer, and a pressure sensitive adhesive disposed on the fibrous layer, the method includes adhering the conductive article to a part of the body through the pressure sensitive adhesive composition.

In one aspect the invention features a conductive article that includes a hot melt superabsorbent polymer composition that includes thermoplastic polymer and superabsorbent polymer particles, and an electrical connector in electrical communication with the hot melt superabsorbent polymer composition. In one embodiment, the hot melt superabsorbent polymer composition further includes a conductive additive that increases the conductivity of the hot melt superabsorbent polymer composition relative to the conductivity of the hot melt superabsorbent polymer composition without the conductive additive. In other embodiments, the hot melt superabsorbent polymer composition further includes a conductive additive selected from the group consisting of polar liquid, metal salt, and combinations thereof. In some embodiments, the hot melt superabsorbent polymer composition is a pressure sensitive adhesive composition.

In one embodiment, the conductive article further includes a fibrous layer that includes a first surface and a second surface opposite the first surface, and a pressure sensitive adhesive composition disposed on the first surface of the fibrous layer. In some embodiments, the hot melt superabsorbent polymer composition is disposed on the fibrous layer. In other embodiments, the conductive article further includes a liquid impermeable layer disposed between the fibrous layer and the hot melt superabsorbent polymer composition. In some embodiments, the liquid impermeable layer is selected from the group consisting of polymeric films, film coated woven webs, film coated non- woven webs, foams, a one-way liquid permeable layer, and combinations thereof. In some embodiments, the electrical connector is in contact with the hot melt superabsorbent polymer composition and extends through the liquid impermeable layer and through the fibrous layer. In another embodiment, the conductive article defines an opening that extends from the hot melt superabsorbent polymer composition, through the liquid impermeable layer, and through the fibrous layer.

In another embodiment, the conductive article further includes a liquid impermeable layer. In one embodiment, the conductive article further includes a liquid impermeable layer, and a metal layer disposed between the hot melt superabsorbent polymer composition and the liquid impermeable layer. In another embodiment, the conductive article further includes a pressure sensitive adhesive composition disposed on the liquid impermeable layer.

In another aspect, the invention features a conductive article that includes a first layer that includes a hot melt superabsorbent polymer composition that includes thermoplastic polymer and superabsorbent polymer, and a second layer disposed on the first layer, the second layer defining an opening that extends through the second layer and to the hot melt superabsorbent composition. In one embodiment, the conductive article further includes an electrical connector disposed in the opening in the second layer and in electrical communication with the hot melt superabsorbent polymer composition of the first layer. In some embodiments, the hot melt superabsorbent polymer composition is a pressure sensitive adhesive composition. In other embodiments, the conductive article further includes a pressure sensitive adhesive composition for adhering the conductive article to a surface. In other aspects, the invention features a method of using a conductive article disclosed herein, the method including contacting the skin of a mammal with the hot melt superabsorbent polymer composition of the conductive article. In one embodiment, the method further includes contacting the hot melt superabsorbent polymer composition with a polar liquid prior to contacting the skin of the mammal with the hot melt superabsorbent polymer composition. In another embodiment, the method further includes monitoring a function of the mammal. In some embodiments, the method further includes monitoring the cardiac activity of the mammal. In other embodiments, the method further includes delivering electrical energy to the mammal. In some embodiments, the method further includes applying a current to the electrical connector.

In some aspects, the invention features a method of using a conductive article disclosed herein, the method including adhering the conductive article to the skin of a mammal.

In another aspect, the invention features a method of making an electrically conductive article, the method including coupling an electrical connector and a hot melt superabsorbent polymer composition such that the electrical connector is in electrical communication with the hot melt superabsorbent polymer composition, the hot melt superabsorbent polymer composition includes thermoplastic polymer and superabsorbent polymer. In one embodiment, the hot melt superabsorbent polymer composition further comprises a conductive additive selected from the group consisting of polar liquid, metal salt, and combinations thereof. In some embodiments, the method further includes contacting the hot melt superabsorbent polymer composition with a polar liquid including, e.g., water, saline, glycol, alcohols, and combinations thereof

In other aspects, the invention features an electrode kit that includes a first component that includes a conductive article disclosed herein and a second component that includes a conductive additive. The present invention features electrically conductive articles, e.g., electrocardiogram pads, defibrillator pads, neuromuscular stimulation pads, and transcutaneous electro-nerve stimulator, that exhibit good conductivity, good flexibility and an ability to conform to a surface with which they are in contact.

Other features and advantages will be apparent from the following description of the preferred embodiments, the drawings, where like reference numerals indicate like elements, and from the claims. GLOSSARY

In reference to the invention, these terms have the meanings set forth below: The term "tackifier" means a component that imparts tack to a composition. The term "tack" means the property of a material that enables it to form a bond of measurable strength immediately on contact with another surface.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a plan view of a body facing side of an electrocardiogram pad according to one embodiment;

FIG. 2 shows a plan view of the distal side of an electrocardiogram pad according to another embodiment;

FIG. 3 shows a cross-sectional view of the electrocardiogram pad of FIG. 2, taken along view A-A;

FIG. 4 shows a cross-sectional view of an electrocardiogi-am pad according to another embodiment; FIG. 5 shows a cross-sectional view of an electrocardiogram pad according to another embodiment;

FIG. 6 shows a cross-sectional view of an electrocardiogram pad according to another embodiment;

FIG. 7 shows a cross-sectional view of an electrocardiogram pad according to another embodiment;

FIG. 8 shows a cross-sectional view of a conductive article according to another embodiment.

DETAILED DESCRIPTION

A conductive article in the form of an electrocardiogram pad 10 that is flexible and conformable to a surface such as the skin includes a proximal surface (i.e., a surface of the article intended to be placed in contact with a user) that includes a conduction region 12 that includes a hot melt superabsorbent polymer composition 13 that includes a thermoplastic polymer and superabsorbent polymer particles 14, a pressure sensitive adhesive composition 11, and a fibrous exterior layer 15, which forms the distal surface (i.e., a surface of the article intended to be farthest from the user) of the electrocardiogram pad 10, as illustrated in FIGS. 1-3. The pressure sensitive adhesive composition 11 extends along the perimeter of the proximal surface of the fibrous layer 15 such that it surrounds the conduction region 12. The pressure sensitive adhesive 11 is available for contact with the patient's skin so that the electrocardiogram pad 10 can be adhered to the skin through the adhesive composition 11. In use, at least a portion of the conduction region 12 of the electrocardiogram pad

(i.e., the hot melt superabsorbent polymer composition and any additional layers to the proximal side of the hot melt superabsorbent polymer composition, where present) is contacted, preferably saturated, with a polar liquid (e.g., water, saline, glycol, alcohols, and combinations thereof). The electrocardiogram pad is then placed at the desired location on the patient causing the proximal surface of the conduction region to contact the skin. Pressure is then applied to the electrocardiogram pad 10 until a secure bond is formed between the pressure sensitive adhesive 11 and the patient's skin. Subsequently, an electrode from a readout device, e.g., electrocardiograph, is connected to the hot melt superabsorbent polymer composition of the electrocardiogram article. An electrode can be placed in contact with the hot melt superabsorbent polymer in a variety of ways including, e.g., by piercing through the fibrous layer 15, and any intermediate layers, and into the hot melt superabsorbent polymer composition or inserting the electrode beneath the fibrous layer and into the hot melt superabsorbent polymer composition. After the necessary readings are taken, the electrocardiogram pad can be removed from the skin, preferably leaving little to no residue, and then discarded.

In another embodiment, the electrocardiogram pad 40 includes a liquid impermeable exterior layer 16a, a hot melt superabsorbent polymer composition 13a that includes superabsorbent polymer particles 14a, and a pressure sensitive adhesive composition l la, as illustrated in FIG. 4. In FIG. 5, the electrocardiogram pad 50 includes a fibrous exterior layer 15b, a liquid impermeable layer 16b, a hot melt superabsorbent polymer composition 13b that includes superabsorbent polymer particles 14b, and a pressure sensitive adhesive composition 1 Ib. The fibrous exterior layer 15b provides an appealing tactile sensation to the electrocardiogram pad 50 relative to an exterior surface of an impermeable layer in the form of a plastic film. The liquid impermeable layer and the fibrous layer can be separate components bonded to each other through a construction adhesive. Alternatively, the liquid impermeable layer and the fibrous layer can be a composite (e.g., a laminate) formed, e.g., by coating and simultaneously bonding the liquid impermeable layer to the fibrous layer. In other embodiments, the electrocardiogram pad includes an opening that extends from the exterior surface of the pad to the hot rnelt superabsorbent polymer composition and the electrode can be placed in contact with the hot melt superabsorbent polymer composition through the opening. FIG. 6, for example, illustrates an embodiment of an electrocardiogram pad 60 that includes a fibrous exterior layer 15c, a liquid impermeable layer 16c, a hot melt superabsorbent polymer composition 13c that includes superabsorbent polymer particles 14c, and a pressure sensitive adhesive composition 1 Ic. Electrocardiogram pad 60 also includes an opening 26, defined by wall 27 that extends from the distal surface of the hot melt superabsorbent composition to the distal surface of the fibrous layer 15. The opening 26 is dimensioned to accommodate an electrode. Other embodiments are within the claims. In FIG. 7, for example, an electrocardiogram pad 70 includes a fibrous exterior layer 15d, a liquid impermeable layer 16d, a hot melt superabsorbent polymer composition 13d that includes superabsorbent polymer particles 14d, and a pressure sensitive adhesive composition Hd. Electrocardiogram pad 70 further includes a conductor (e.g., electrical connector) 25 that is in contact with and that extends from the hot melt superabsorbent polymer composition 13 and through the fibrous layer 15 such that it is available for contact with an electrode. Electrical connector 25 is in electrical communication with the hot melt superabsorbent polymer composition 13d and facilitates operably coupling an electrode or other source of current to the hot melt superabsorbent polymer composition 13d. Useful electrical connectors can be formed from any electrically conductive material including, e.g., metals, conductive polymers, polymer composites that include conductive materials (e.g., graphite, carbon black and metal particles and combinations thereof), and combinations thereof.

The electrocardiogram pad can be of any size and preferably is of a size suited to its intended application. While the electrocardiogram pad is illustrated as being generally round in shape it can exhibit a variety of shapes including, e.g., polygonal (e.g., rectangular, square, triangular, pentagonal, heptagonal, and hexagonal), and oval.

Electrocardiogram pad can be provided in any suitable packaging using any suitable packaging material. The electrocardiogram pad is preferably provided in an air tight sealed package, which is optionally sterilized. Preferred packaging materials are vapor impermeable and enable easy removal of the electrocardiogram pad for subsequent use.

In some embodiments, it may be desirable to treat at least one portion or component of the conduction region (e.g., the hot melt superabsorbent polymer composition) with a polar liquid. Useful treatment methods include, e.g., contacting, coating, spraying, soaking, and saturating the component with the polar liquid. The treated electrocardiogram pad is preferably sealed in a package to prevent the polar liquid from evaporating, to aid in the ease of handling during shipping and storage, and prior to use. A release liner optionally can be disposed over the hot melt superabsorbent polymer composition to prevent the polar liquid from evaporating.

Other embodiments are within the claims. FIG. 8 illustrates an alternative embodiment of a conductive article 110 that includes a fibrous layer 112, a liquid impermeable layer 114, a metallic conductor 122 (e.g., tin, aluminum, and stainless steel), and a hot melt superabsorbent polymer composition 118 that is coextensive with the metallic conductor 122. A pressure sensitive adhesive 116 extends along the perimeter of the proximal surface of the liquid impermeable layer 114 and is available for contact with the patient's skin so that the conductive article 110 can be adhered to the skin through the pressure sensitive adhesive 116.

Although the conductive articles disclosed herein have been described with respect to their use in conjunction with electrocardiograph devices, the articles are also well suited for use in other electrical conductive applications including, e.g., defibrillators, pacing machines, TENS Units (i.e., transcutaneous electro-nerve stimulator), and neuromuscular stimulators. An example of a defibrillator pad is described in U.S. Patent No. 6,330,481 (Van Wijk et al.) and incorporated herein. An example of a pacing machine pad is described in U.S. Patent No. 6,993,395 (Craige et al.) and incorporated herein. An example of a TENS Unit pad is described in U.S. Patent No. 6,643,532 (Axelgaard) and incorporated herein. An example of a neuromuscular stimulator pad is described in U.S. Patent No. 6,163,725 (Craige et al.) and incorporated herein.

The conductive article can be constructed for a variety of uses including, e.g., monitoring a function of a mammal (e.g., monitoring cardiac activity), delivering electrical energy (e.g., defibrillation and cardiac pacing functions), and providing a current to the electrical connector.

In other embodiments, an electrode is placed through one or more layers of the conductive article and in contact with the hot melt superabsorbent polymer composition so as to be in electrical communication with the hot melt superabsorbent polymer composition.

HOT MELT SUPERABSORBENT POLYMER

The hot melt superabsorbent polymer composition can be any suitable hot melt superabsorbent polymer composition that includes a blend of thermoplastic polymer and superabsorbent polymer particles including, e.g., a hot melt adhesive composition that includes superabsorbent polymer particles. In some embodiments, superabsorbent polymer particles are also present on a surface of the hot melt superabsorbent polymer composition. The hot melt superabsorbent polymer composition can be tacky (e.g., hot melt superabsorbent polymer pressure sensitive adhesive compositions) or nontacky. Useful thermoplastic polymers include, e.g., styrenic block copolymers, polyolefins (e.g., amorphous and crystalline polyolefins including homogeneous and substantially linear ethylene/alpha-olefin interpolymers), interpolymers and copolymers of ethylene including, e.g., ethylene-vinyl acetate, ethylene-vinyl acetate ethylene-acrylic acid, ethylene-methacrylic acid, ethylene-methyl acrylate, ethylene-ethyl acrylate and ethylene n-butyl acrylate and derivatives (e.g., incorporating at least two comonomers), polyacrylic acids, polymethacrylic acids, polyacrylates, polyvinyl acetates, polylactic acids, polylactides, caprolactone polymers, poly (hydroxy-butyrate/hydroxyvalerate), polyvinyl alcohols, polyesters, copolyesters (e.g., biodegradable copolyesters), poly(ethylene oxide)polyether amide, polyester ether block copolymers, polyvinyl pyrrolidone, polyvinyl pyrrolidone-vinyl acetate copolymer, polyetheroxazoline, polyvinyl ethers (e.g., polyvinyl methyl ether), polyamides, polyacrylamide, and combinations thereof.

A wide variety of block copolymers are useful including, e.g., A-B-A triblock copolymers, A-B diblock copolymers, and (A-B)n radial block copolymers, and branched and grafted versions thereof, wherein the A blocks are non-el astomeric polymer blocks , typically comprising polystyrene, and the B blocks are unsaturated conjugated diene or hydrogenated version thereof. Suitable B blocks include, e.g., isoprene, butadiene, ethylene/butylene (hydrogenated butadiene), ethylene/propylene (hydrogenated isoprene), and combinations thereof. Useful block copolymers are commercially available under the K-RATON D and G series of trade designations from Shell Chemical Company (Houston, Texas), EUROPRENE Sol T trade designation from EniChem (Houston, Texas), and Vector® series of trade designations from Exxon (Dexco) (Houston, Texas).

Useful commercially available polyolefins include, e.g., AFFINITY substantially linear ethylene polymers polyolefin plastomers from The Dow Chemical Company (Midland, Michigan) and EXACT homogeneous linear ethylene polymers from Exxon Chemical Company (Houston, Texas). Useful amorphous polyolefins and amorphous polyalphaolefins include homopolymers, copolymers, and terpolymers Of C₂-Cs alphaolefins. Useful commercially available amorphous polyalphaolefins include, e.g., REXTAC and REXFLEX propylene based homopolymers, ethylene-propylene copolymers and butene-propylene copolymers available from Rexene (Dallas, Texas), VESTOPLAST alpha-olefin copolymers available from Hiils (Piscataway, New Jersey).

Any suitable superabsorbent polymer can be included in the composition. Superabsorbent polymers are also referred to as water-insoluble absorbent hydrogel- forming polymers, "hydrogel-forming" polymers, and "hydrocolloids." Superabsorbent polymers are able to absorb many times their own weight in water. Useful superabsorbent polymers include at least partially crosslinked, at least partially neutralized polymers that gel when contacted with water and are preferably substantially water insoluble. Suitable superabsorbent polymers include, e.g., polysaccharides (e.g., carboxymethyl starch, carboxymethyl cellulose, and hydroxypropyl cellulose), polyvinyl alcohol, polyvinyl ethers, polyvinyl pyridine, polyvinyl morpholinione, N,N-dimethylaminoethyl, N,N- diethylaminopropy], acrylates, methacrylates, and the quaternary salts thereof. The superabsorbent polymer preferably includes a plurality of functional groups, e.g., sulfonic acid groups, carboxy groups and combinations thereof.

Suitable superabsorbent polymers are prepared from polymerizable, unsaturated, acid-containing monomers including, e.g., olefinically unsaturated acids and anhydrides having at least one carbon-carbon olefinic double bond including, e.g., olefinically unsaturated carboxylic acids and acid anhydrides, olefinically unsaturated sulfonic acids and combinations thereof. Useful olefinically unsaturated carboxylic acid and carboxylic acid anhydride monomers include, e.g., acrylic acid, methacrylic acid, ethacrylic acid, chloroacrylic acid, cyanoacrylic acid, crotonic acid, phenylacrylic acid, acrytoxypropionic acid, sorbic acid, chlorosorbic acid, angelic acid, cinnamic acid, p-chlorocinnamic acid, stearylacrylic acid, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, aconitic acid, maleic acid, fumaric acid, tricarboxyethylene acid anhydride, maleic acid anhydride, and combinations thereof.

Useful olefinically unsaturated sulfonic acid monomers include aliphatic and aromatic vinyl sulfonic acids (e.g., vinylsulfonic acid, allyl sulfonic acid, vinyl toluene sulfonic acid and styrene sulfonic acid), acrylic and methacrylic sulfonic acids (e.g., sulfoethyl acrylate, sulfoethyl methacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-methacryloxypropyl sulfonic acid and 2-acrylamide-2- methylpropane sulfonic acid), and combinations thereof. Useful superabsorbent polymers that include carboxy groups include, e.g., hydrolyzed starch-acrylonitrile graft copolymers, partially neutralized hydrolyzed starch- acrylonitrile graft copolymers, starch-acrylic acid graft copolymers, partially neutralized starch-acrylic acid graft copolymers, saponified vinyl acetate-acrylic ester copolymers, hydrolyzed acrylonitrile or acrylamide copolymers, slightly network crosslinked polymers of any of the foregoing copolymers, partially neutralized polyacrylic acid, and slightly network crosslinked polymers of partially neutralized polyacrylic acid. These polymers are disclosed, e.g., in U.S. Patent Nos. 4,076,663, 4,093,776, 4,666,983 and 4,734,478 and incorporated herein.

The absorbent gelling particles can have any suitable property including, e.g., size, shape, morphology and combinations thereof. The superabsorbent particles preferably are spherical or substantially spherical and preferably have an average particle size no greater than about 400 μm, no greater than about 350 μm, no greater than about 200 μm, no greater than about 150 μm, no greater than about 100 μm, no greater than about 100 μm, no greater than about 50 μm, no greater than about 40 μm, at least about 10 μm, at least about 20 μm, or even about 20 μm to about 30 μm.

5 Useful commercially available superabsorbent particles include, e.g., sodium polyacrylate superabsorbent particles available under the AQUA KEEP series of trade designations including, e.g., particles having a median particle size of from about 20 μm to about 30 μm available under the trade designation AQUA KEEP 10SH-NF, particles having an average particle size of from 200 μm to 300 μm available under the trade

10 designation AQUA KEEP 10SH-P, particles having an average particle size of from 320 μm to 370 μm available under the trade designation AQUA KEEP SA60S, particles having an average particle size of from 350μm to 390 μm available under the trade designations AQUA KEEP SA60SX, SA55SX II and SA 60SL II, and particles having an average particle size of from 250 μm to 350 μm available under the trade designation

15 AQUA KEEP SA60N TYPE II from Sumitomo Seika Chemicals Col, Ltd. (Japan). Useful superabsorbent polymer forms include, e.g., particles, granules, flakes, puiveruients, interparticle aggregates, interparticle crosslinked aggregates, fibers, foams, and combinations thereof.

The hot melt superabsorbent polymer composition preferably includes

20 superabsorbent polymer particles in an amount of at least about 2 % by weight, at least about 5 % by weight, at least about 10 % by weight, at least about 20 % by weight, at least about 30 % by weight, at least about 40 % by weight, at least about 50 % by weight, no greater than about 85 % by weight, or even no greater than about 75 % by weight.

The hot melt superabsorbent polymer composition can also include other additives

25 including, e.g., plasticizers, tackifiers, waxes, antioxidants, biocides, chitosan, antimicrobial agents, zeolites, carbon black, pigments, fillers (e.g., titanium dioxide and hydrophilic fillers), surfactants, phosphites (e.g., IRGAFOS 168), antiblock additives, and combinations thereof.

Useful plasticizers include phthalate plasticizers (e.g., dioctyl phthalate and butyl

30 benzyl phthalate (e.g., Santicizer 160 from Monsanto)), liquid polyesters (e.g., Dynacol 720 from HuIs, liquid polymeric plasticizer an example of which is commercially

12

T O available from C. P. Hall, benzoate plasticizers (e.g., 1,4-cyclohexane dimethanol dibenzoate (e.g., BENZOFLEZ 352 commercially available from Velsicol), diethylene glycol/dipropylene glycol dibenzoate (e.g., BENZOFLEZ 50 commercially available from Velsicol), and diethylene glycol dibenzoate (e.g., commercially available 2-45 High Hydroxyl (Velsicol)), phosphite plasticizers (e.g., t-butyl diphenyl phosphate (e.g., SANTICIZER 154 from Monsanto)), liquid rosin derivatives having Ring and Ball softening points below about 60⁰C including, e.g., methyl esters of hydrogenated rosin (e.g., Hercoyn D from Hercules), vegetable oils, and animal oils (e.g., glycerol esters of fatty acids and polymerizable products thereof, citric acid esters (e.g., citric acid esters commercially available under the CITROFLEX series of trade designations), and toluene sulfonamide.

Useful water soluble or water dispersible plasticizers include polyethylene glycol having a molecular weight less than about 2000, derivatives of polyethylene glycol including Pycal 94, the phenyl ether of PEG available from ICI; ethoxylated bis phenol A (e.g., Macol 206 EM from PPG Industries) and dionyl phenol ethyloxylates (e.g., Surfonic DNP from Huntsman Chemical Corp.).

Other useful plasticizers include hydrocarbon oils (paraffinic oils, naphthenic oils and oils having low aromatic content), polybutene, liquid tackifying resins and liquid elastomers. Plasticizer oils are preferably low in volatility, transparent and have as little color and odor as possible.

Useful waxes include 12-hydroxystearamide, N-(2-hydroxy ethyl 12-hydroxy stearamide (Paricin 220 and 285 from CasChem), stearamide (Kemamide S from Witco), glycerin monostearate, sorbitan monostearate, and 12-hydroxy stearic acid. Other useful waxes include paraffin waxes, microcrystalline waxes, Fischer-Tropsch, polyethylene and by-products of polyethylene. Also useful in combination with the above waxes are waxes such as N,N'-ethylene-bis stearamide (Kemamide W-40 from Witco), hydrogenated castor oil (castor wax), oxidized synthetic waxes, and functionalized waxes such as oxidized polyethylene waxes (Petrolite E-1040).

Waxes are usefully employed to reduce viscosity as well as increase the blocking resistance at concentrations ranging from about 2 % by weight to about 25 % by weight, or even from about 10 % by weight to about 20 % by weight. Useful tackifying agents include, e.g., resins derived from renewable resources such as rosin derivatives including wood rosin, tall oil and gum rosin, as well as rosin esters, natural and synthetic terpenes and derivatives thereof, aliphatic, aromatic and mixed aliphatic-aromatic petroleum based tackifiers. Examples of useful hydrocarbon 5 resins include alpha-methyl styrene resins, branched and unbranched C₅-C10 resins and styrenic and hydrogenated modifications thereof. Useful tackifying resins range from being a liquid at 37°C to having a ring and ball softening point of about 135⁰C. The composition can include tackifying resin in an amount from 0 % by weight to about 50 % by weight, from about 5 % by weight to about 40 % by weight, or even from about 10 %

10 by weight to about 20 % by weight.

Useful antioxidants include, e.g., hindered phenolics (e.g., IRGANOX 1010 and IRGANOX 1076).

Hydrophilic fillers are a preferred class of additives, which are useful to alter the surface properties and/or increase the rate of absorption. Hydrophilic fillers include

15 calcium carbonate, hydroxyethyl cellulose, hydroxypropyl cellulose, starch and cellulose esters (e.g., acetates), attagel clay, guargum, bentonite, hectonite, diatomaceous earth, talc, and combinations thereof.

Suitable surfactants include nonionic, anionic, and silicone surfactants. The composition can include surfactant in an amount from 0 % by weight to about 25 % by

20 weight, or even from about 5 % by weight to about 15 % by weight.

Useful antimicrobial agents can be dissolved or suspended in the thermoplastic polymer of the composition. The antimicrobial agent can be mixed into a hot melt superabsorbent polymer composition, applied to the surface thereof, and combinations thereof. The antimicrobial also can be introduced into the composition by adding the

25 antimicrobial in a powder form or adding antimicrobial agent carried on a powder support to the composition. Any suitable antimicrobial agent can be used including, e.g., sulfadiazine, silver ions, silver sulfadiazine, benzalkonium chloride, cetalkonium chloride, methylbenzethonium, neomycin sulfate, hexachlorophene, eosin, penicillin G, cephalothin, cephaloridine, tetracycline, linkomycin, nystatin, kanamycin, penicillinase-resistant

30 penicillins, fradiomycin sulfate, camphor, and combinations thereof. In other methods, the antimicrobial agent is added to an aqueous solution, which is then applied to the surface of

14

\ ά the hot melt superabsorbent polymer composition. The amount of antimicrobial agent should be sufficient to provide an effective antimicrobial concentration or dose rate of the material to the skin surface. Typical concentrations of standard antimicrobials range from about 0.01 % by weight to 5 % by weight based on the weight of the composition. Useful hot melt superabsorbent polymer compositions are described in, e.g., U.S.

Patent Nos. 6,534,572, and 6,458,877, and U.S. Patent Application Serial Nos. 10/050,375 (published as U.S. Publication No. 2003/0134552), and 11/007,470, and incorporated herein. Useful hot melt superabsorbent polymer compositions are commercially available under the HYDROLOCK series of trade designations from H.B. Fuller Company (Vadnais Heights, Minnesota).

The hot melt superabsorbent polymer composition optionally includes a conductive additive that increases the conductivity of the hot melt superabsorbent polymer composition relative to the conductivity of the hot melt superabsorbent polymer composition without the conductive additive. The conductive additive can be added to the hot melt superabsorbent polymer composition at a variety of points including, e.g., during manufacture of the hot melt superabsorbent polymer composition, during the conductive article manufacturing process, prior to use of the conductive article and combinations thereof. Any additive that increases the electrical conductivity of the hot melt superabsorbent polymer composition and is non-toxic to mammals can be included in the hot melt superabsorbent polymer composition. Useful conductive additives include, e.g., polar liquids, metal salts and a combination thereof. Useful polar liquids include, e.g., water, saline, glycol, alcohols, and combinations thereof.

The conductive additive can be added to the hot melt superabsorbent polymer composition using any suitable technique including, e.g., contacting, spraying, soaking, saturating, brushing, mixing and combinations thereof. The hot melt superabsorbent polymer composition can be provided in a variety of forms including, e.g., a coating (e.g., a continuous or discontinuous coating), a film (e.g., a continuous or discontinuous film), a spray pattern, a mass, and combinations thereof, using any suitable technique including, e.g., contact coating, non-contact coating, spraying (e.g., spiral spraying and random spraying), extrusion (e.g., single screw extrusion and twin screw extrusion), slot coating, melt blown, foaming, engraved roller, gravure, screen printing, flexographic printing and combinations thereof.

The configuration, location and amount of the hot melt superabsorbent polymer composition present in the conductive article is selected to optimize the conductive property of the conductive article. The hot melt superabsorbent polymer composition can be present in the conductive article in a variety of configurations including, e.g., random, pattern, stripes, dots having a variety of shapes (e.g., round, oval, square, diamond, and triangle), wavy lines, spiral spray, fanciful forms (e.g., leaves, flowers, and petals), and combinations thereof. The hot melt superabsorbent polymer composition is preferably in the form of a continuous layer. Any amount of hot melt superabsorbent polymer composition can be present in the article. Preferably the conductive article includes hot melt superabsorbent polymer composition in an amount of at least about 20 g/m², at least about 50 g/m², at least about 100 g/m², at least about 150 g/m², at least about 250 g/m², at least about 500 g/m², or even from about 50 g/m² to about 500 g/m².

LIQUE) IMPERMEABLE LAYER

The liquid impermeable layer prevents liquids from escaping from the conductive article. The liquid impermeable layer is liquid impervious (e.g., impervious to water, saline, alcohol, and glycols) and flexible. The liquid impermeable layer can also exhibit elastic or extensible properties such that it can stretch in at least one direction and is preferably biodegradable. Useful methods of making a layer extensible using a mechanical operation include, e.g., pleating, corrugating, ring rolling, and those methods disclosed, e.g., in U.S. Patent 5,518,801, the relevant portions of which are incorporated herein. The liquid impermeable layer can be breathable or non-breathable. The term

"breathable" refers to the property of allowing vapors to transfer there through, while preventing the transfer of liquids including such liquids as water, saline, alcohol, and glycols. Suitable breathable films include hydrophilic films including monolithic films. The breathability of a film is determined by its moisture vapor transmission rate. The liquid impermeable layer preferably exhibits a moisture vapor transmission rate of about 100 g/m²/day, at least about 500 g/m²/day, at least about 1000 g/m²/day or even at least W

about 2500 g/m²/day when measured according ASTM E96-95 Upright Cup Method entitled, "Standard Test Methods for Water Vapor Transmission of Materials," March 6, 1995.

Useful liquid impermeable layers include, e.g., polymeric films (e.g., thermoplastic films of polymers including e.g., polyethylene, polypropylene, polyester and ethylene vinyl acetate), composites including, e.g., film-coated woven and nonwoven webs, foams (e.g., polyurethane foams including, e.g., breathable polyurethane foams), and combinations thereof.

Useful liquid impermeable composites (e.g., laminates) include a fibrous web (e.g., a woven or nonwoven web) and a continuous film bonded thereto. The fibrous web provides a soft touch to the exterior surface of the liquid impermeable layer and therefore the conductive article. Examples of useful methods for preparing composites are described in U.S. Patent Nos. 6,583,332, 5,827,252, and 6,843,874 and incorporated herein.

In some embodiments, the liquid impermeable layer can include a one-way liquid permeable layer, i.e., a layer that allows liquid to pass from a first surface (e.g., an exterior surface) to a second surface (e.g., an interior surface), and inhibits or preferably prevents liquids from moving from the second surface to the first surface. Examples of useful oneway liquid permeable layers are described in U.S. Patent No. 6,228,462, and incorporated herein. The liquid impermeable layer is preferably thin and conformable to the body. The liquid impermeable layer preferably has a thickness of from about 12 microns to about 200 μm, no greater than about 150 μm, no greater than about 100 μm, or even from about 12 μm to about 25 μm. Conformability is somewhat dependent on thickness, thus the thinner the film the more conformable the film. Useful liquid impermeable materials can be made from polymers commercially available under the trade designation PEBAX from Arkema, Inc. (Pittsburgh, PA) and HYTREL from E. I. Du Pont de Nemours and Company (Wilmington, Delaware).

SKIN ATTACHMENT PRESSURE SENSITIVE ADHESIVE Useful pressure sensitive adhesives that are suitable for application to the skin include pressure sensitive adhesive compositions in which the base polymer includes, e.g., block copolymer (e.g., styrene-isoprene-styrene, styrene-butadiene-styrene, styrene- ethylene-butylene-styrene, and styrene-ethylene-propylene-styrene), acrylic acid, acrylate, silicone, polyurethane, polyurethane elastomers, polyester, polyester elastomers (e.g., aliphatic-aromatic copolyesters, copolyester-copolyether and copolyether-copolyamide), polylactic acid, polyoxyalkanoates, and combinations thereof.

Useful adhesives for skin attachment include those adhesives described, e.g., in U.S. Patent No. 4,917,697, U.S. Patent Application Serial No. 10/934,266 filed August 1, 2002, and U.S. Patent Application Serial No. 10/211,162 filed September 3, 2004 and incoiporated herein. Suitable commercially available skin attachment adhesives are available, e.g., under the trade designations LUNATAC D-1053, HL 2711 and HL 2539 from H.B. Fuller Co. (St. Paul, Minnesota). A useful commercially available styrene- isoprene-styrene skin attachment adhesive is available under the trade designation HM 1902 from H.B. Fuller Company (St. Paul, MN).

Other useful skin attachment adhesives are described, e.g., in U.S. Patent Nos. 5,614,310, 6,171,985, and 6,198,016, and PCT Publication Nos. WO 99/13866 and WO 99/13865.

The skin attachment adhesive can optionally include medicaments useful for enhancing healing and antimicrobial agents (e.g., iodine) to prevent infection.

RELEASE LINER

The conductive article can optionally include a release liner to protect the utility of the pressure sensitive adhesive prior to use and for ease of handling. Where present, the release liner is removed prior to using the conductive article. Any suitable release liner can be used including, e.g., liners made of or coated with polyethylene, polypropylene and fluorocarbons, and silicone coated release papers and polyester films. Useful commercially available release liners include, e.g., silicone coated release papers available under the POLYSLIK trade designations including POLYSLIK S-8004 83 pound bleached silicone release paper from H. P. Smith Co. (Chicago, IH.) and 2-80-BKG-157 80 pound bleached two-sided silicone coated paper from Daubert Chemical Co., (Dixon, 111.). The components of the conductive article can be joined together using any suitable mechanism including, e.g., adhesive bonding, stitching, heat bonding, pressure bonding, dynamic mechanical bonding, ultrasonic bonding, simultaneously or sequentially extruding at least two components of the conductive article, and combinations thereof. Methods of attaching components of a conductive article to each other are well known to the skilled artisan.

CONSTRUCTION ADHESIVE

Where present, the construction adhesive can be any adhesive suitable for maintaining at least two of the components of the conductive article in fixed relation to each other. The construction adhesive can be applied to the periphery of a layer, the major surface of the layer, the perimeter of the conductive article and combinations thereof.

When applied to the perimeter or periphery, the construction adhesive can be in the form of a continuous or discontinuous coating. When applied to a major surface of the layer, the construction adhesive is provided as a discontinuous coating. The construction adhesive can be applied as a discontinuous coating using any suitable method that produces any suitable discontinuous coating including, e.g., a spiral spray, random spray, gravure, dot and random fibridization. Useful construction adhesives include, e.g., hot melt adhesives, pressure sensitive adhesives, hot melt pressure sensitive adhesives, and blends thereof. One example of a suitable commercially available construction adhesive is HL-1713 styrene-isoprene-styrene based construction adhesive from H.B. Fuller Company (St. Paul, Minnesota).

The components can be joined together in any suitable manner including, e.g., joining such that each component is directly secured to another component, a component is secured to an intermediate component, a component is integral with another component, and combinations thereof. The conductive article can have in a variety of shapes and the conductive article in its entirety or any component thereof can have any combination of height, width and depth. The conductive article can also be packaged as an electrode kit that includes a conductive article and a conductive additive that can be added to the hot melt superabsorbent polymer composition of the conductive article. The invention will now be described by way of the following examples. EXAMPLES Example 1-4

The thermoplastic compositions of each of Examples 1-4 are prepared by combining the components (other than the superabsorbent particles) in the amounts specified in Table 1 in units of % by weight and heating the composition to from 200T to 250°F while mixing. Superabsorbent particles, in the amount specified in Table 1 in units of % by weight, are then added to the molten thermoplastic composition with mixing.

Table I

Calsol 5555 naphthenic oil (Calumet Refining Co., Chicago, Illinois).

²Kraton G-1651 styrene-ethylene-butadiene-styrene block copolymer (Shell Chemical Company).

³Rhodacal DS-10 sodium dodecylbenzene sulfonate (Rhone Poulenc, Cranberry, New Jersey).

⁴AquaKeep lOSH-NF superabsorbent particles having an average diameter of 20 to 30 urn (Sumitomo Seika, Osaka, Japan)

⁵Nyflex 222B naphthenic oil (Nynas Petroleum, Stockholm, Sweden).

The compositions of Examples 1-4 are expected to be flexible, pliable and stretchable. After 20 ml of water is added to a 20 g sample of each of the compositions of Examples 1-4, the resulting compositions are expected to exhibit relatively greater pliability, flexibility, stretchability, and conformability. Example 5

Twenty milliliters of water is added to a 20 g sample of the hot melt superabsorbent polymer composition of Example 3. After 24 hours the resistance of the composition is measured and is expected to be from 1.6 milliohms to 1.9 milliohms.

All references disclosed herein are incorporated herein by reference.

Other embodiments are within the claims. Although the article has been described as including a hot melt superabsorbent polymer composition comprising a blend of thermoplastic polymer and superabsorbent polymer particles, in other embodiments the article alternatively or additional includes a thermoplastic composition and superabsorbent polymer particles disposed on at least one surface of the thermoplastic composition and optionally extending into the thermoplastic composition from the at least one surface.

Although the use of the article has been described as including adding a polar liquid to the hot melt superabsorbent polymer composition, the hot melt superabsorbent polymer composition can include a conductive additive of an appropriate type in a sufficient amount such that the conductivity of the article is sufficient for its intended use rendering the addition of a polar liquid thereto unnecessary.

What is claimed is:

Claims

1. A conductive article comprising: a hot melt superabsorbent polymer composition comprising thermoplastic polymer and superabsorbent polymer particles; and an electrical connector in electrical communication with the hot melt superabsorbent polymer composition.

2. The conductive article of claim 1 , wherein the hot melt superabsorbent polymer composition further comprises a conductive additive that increases the conductivity of the hot melt superabsorbent polymer composition relative to the conductivity of the hot melt superabsorbent polymer composition without the conductive additive.

3. The conductive article of claim 1, wherein the hot melt superabsorbent polymer composition further comprises a conductive additive selected from the group consisting of polar liquid, metal salt, and combinations thereof.

4. The conductive article of claim 1, wherein the hot melt superabsorbent polymer composition is a pressure sensitive adhesive composition.

5. The conductive article of claim 1 further comprising: a fibrous layer comprising a first surface and a second surface opposite the first surface; and a pressure sensitive adhesive composition disposed on the first surface of the fibrous layer.

6. The conductive article of claim 5, wherein the hot melt superabsorbent polymer composition is disposed on the fibrous layer.

7. The conductive article of claim 5 further comprising a liquid impermeable layer disposed between the fibrous layer and the hot melt superabsorbent polymer composition.

8. The conductive article of claim 7, wherein the liquid impermeable layer is selected from the group consisting of polymeric films, film coated woven webs, film coated non-woven webs, foams, a one-way liquid permeable layer, and combinations thereof.

9. The conductive article of claim 7, wherein the electrical connector is in contact with the hot melt superabsorbent polymer composition and extends through the liquid impermeable layer and through the fibrous layer.

10. The conductive article of claim 7, wherein the conductive article defines an opening that extends from the hot melt superabsorbent polymer composition, through the liquid impermeable layer, and through the fibrous layer.

11. The conductive article of claim 1 further comprising a liquid impermeable layer.

12. The conductive article of claim 1 further comprising: a liquid impermeable layer; and a metal layer disposed between the hot melt superabsorbent polymer composition and the liquid impermeable layer.

13. The conductive article of claim 11 further comprising a pressure sensitive adhesive composition disposed on the liquid impermeable layer.

14. A conductive article comprising a first layer comprising a hot melt superabsorbent polymer composition comprising thermoplastic polymer and superabsorbent polymer; and a second layer disposed on the first layer, the second layer defining an opening that extends through the second layer and to the hot melt superabsorbent composition.

15. The conductive article of claim 14 further comprising an electrical connector disposed in the opening in the second layer and in electrical communication with the hoL melt superabsorbent polymer composition of the first layer.

16. The conductive article of claim 14, wherein the hot melt superabsorbent polymer composition is a pressure sensitive adhesive composition.

17. The conductive article of claim 14 further comprising a pressure sensitive adhesive composition for adhering the conductive article to a surface.

18. A method of using the conductive article of claim 1, the method comprising contacting the skin of a mammal with the hot melt superabsorbent polymer composition of the conductive article.

19. The method of claim 18, further comprising contacting the hot melt superabsorbent polymer composition with a polar liquid prior to contacting the skin of the mammal with the hot melt superabsorbent polymer composition.

20. The method of claim 18 further comprising monitoring a function of the mammal.

21. The method of claim 18 further comprising monitoring the cardiac activity of the mammal.

22. The method of claim 18 further comprising delivering electrical energy to the mammal.

23. The method of claim 19 further comprising applying a current to the electrical connector.

24. A method of using the conductive article of claim 5, the method comprising adhering the conductive article to the skin of a mammal.

25. A method of making an electrically conductive article, the method comprising coupling an electrical connector and a hot melt superabsorbent polymer composition such that the electrical connector is in electrical communication with the hot melt superabsorbent polymer composition, the hot melt superabsorbent polymer composition comprising thermoplastic polymer and superabsorbent polymer.

26. The method of claim 25, wherein the hot melt superabsorbent polymer composition further comprises a conductive additive selected from the group consisting of polar liquid, metal salt, and combinations thereof.

27. The method of claim 25 further comprising contacting the hot melt superabsorbent polymer composition with a polar liquid.

28. The method of claim 27, wherein the polar liquid is selected from the group consisting of water, saline, glycol, alcohols, and combinations thereof

29. A electrode kit comprising: a first component comprising the conductive article of claim 1; and a second component comprising a conductive additive.