MX2008007540A - Conformable thermal device - Google Patents

Abstract

A chemically-activated conformable thermal device that generates heat uponactivation is provided. The thermal device typically contains an oxidizablemetal that is capable of undergoing an exothermic reaction in the presence ofmoisture and air to generate heat. Although such metals, as well as other componentsof the composition (e.g., carbon), are relatively inflexible and stiff, thepresent inventors have nevertheless discovered that one or more conformablesegments may be employed to impart flexibility and conformability to the thermaldevice. The conformable segments are malleable so that they yield under shearstress and acquire the shape of a surface (e.g., body part) without rupturing.The conformable segments are likewise stiff or hard enough to substantiallyretain the desired shape during use.

Description

CONFORMABLE THERMAL DEVICE Related Requests The present application is a continuation of the Application of the United States of America Series No. 11 / 303,007, which was filed on December 15, 2005.

Background of the Invention Chemically activated warning devices often employ metal reagents (eg, iron powder) that are oxidized in the presence of air and moisture. Because the oxidation reaction is exothermic and generates heat, the resulting device can provide heat when activated. The warning device typically contains other chemical reagents to facilitate the exothermic reaction, such as activated carbon and metal halides. The activated carbon acts as a catalyst to facilitate the exothermic reaction, while the metal halide removes dioxide films from the surface in the metal powder to allow the reaction to proceed to a sufficient extent. Unfortunately, there are several problems with conventional chemically activated warning devices. For example, the carbon and oxidizable metal components of the device are rigid and inflexible. Consequently, during use, it is often difficult to bend and shape the thermal device to a part of the body. As such, there is currently a need for a technique to improve the formability and flexibility of chemically activated thermal devices.

Synthesis of the Invention According to an embodiment of the present invention, a chemically activated thermal device is disclosed comprising an exothermic composition and a conformable segment that is movably constricted within the thermal device. The conformable segment is malleable and has a proportionality ratio of from about 20 to about 40.

Other features and aspects of the present invention are described in more detail below.

Brief Description of the Drawings A complete and capable description of the present invention, which includes the best mode thereof, addressed to one of ordinary skill in the art, is disclosed more particularly in the remainder of the application, which refers to the figures appended hereto. which: Figure 1 illustrates a top view of an embodiment of a conformable thermal device of the present invention; Figure 2 illustrates a cross-sectional view of the conformable thermal device shown in Figure 1; Figure 3 is a thermal response curve showing the temperature (° C) versus the time (minutes) of the samples of Examples 1 to 4; Figure 4 is a thermal response curve showing the temperature (° C) versus the time (minutes) of the samples of Examples 6 to 9; Figure 5 is a thermal response curve showing the temperature (° C) versus the time (minutes) of the samples of Examples 11 to 14; Figure 6 is a thermal response curve showing the temperature (° C) versus the time (minutes) of the samples of Examples 16 to 19; Figure 7 is a thermal response curve showing the temperature (° C) versus the time (minutes) of the samples of Examples 21 to 24; Figure 8 is an evaporation curve showing the liquid weight loss (%) versus the time (minutes) of the moisture retaining layers of Example 27; Y Figure 9 is an evaporation curve showing the liquid weight loss (%) versus the time (minutes) of the moisture retaining layers of Example 32.

Detailed Description of Representative Incorporations Definitions As used herein the term "non-woven fabric or fabric" means a fabric having a structure of individual threads or fibers that are interlaced, but not in an identifiable manner as in a knitted fabric. Fabrics or non-woven fabrics have been formed from many processes such as, for example, meltblowing processes, spinning processes, knitting processes, and so on.

As used herein, the term "meltblowing" refers to a process in which the fibers are formed by extruding a molten thermoplastic material through a plurality of capillary, usually circular, thin vessels such as fibers fused into streams (eg. air example) of converging high speed gas that attenuate the fibers of molten thermoplastic material to reduce their diameter, which can be a microfiber diameter. Then, the meltblown fibers are transported by the high velocity gas stream and are deposited on a collection surface to form a randomly dispersed meltblown fabric. Such a process is described, for example, in United States Patent No. 3,849,241 issued to Butin et al., Which is hereby incorporated by reference in its entirety for all purposes. Generally speaking, meltblown fibers can be microfibers that can be continuous or discontinuous, are generally smaller than 10 microns in diameter, and are generally sticky when deposited on a collection surface.

As used herein, the term "spunbond" refers to a process in which small diameter substantially continuous fibers are formed by extruding a molten thermoplastic material from a plurality of usually circular, fine capillary vessels of a spinning organ with the diameter of the extruded fibers then being rapidly reduced as by, for example, the eductive pull and / or other well-known spinning linkage mechanisms. The production of non-woven fabrics linked by spinning is described and illustrated, for example, in U.S. Patent Nos. 4,340,563 issued to Appel et al., 3,692,618 issued to Dorschner et al., 3,802,817 issued to Matsuki and others, 3,338,992 granted to Kinney, 3,341,394 granted to Kinney, 3,502,763 granted to Hartman, 3,502,538 granted to Levy, 3,542,615 granted to Dobo and others, and 5,382,400 granted to Pike and others, which are incorporated herein. whole by reference to them for all purposes. Spunbonded fibers are generally non-tacky when they are deposited on a collection surface. Spunbonded fibers can sometimes have diameters of less than about 40 microns, and are often between about 5 to about 20 microns.

As used herein, the term "coform" generally refers to composites comprising a stabilized binder or blend of thermoplastic fibers and a second non-thermoplastic material. As an example, coform materials can be made by a process in which at least one melt blown die head is arranged near a channel through which other materials are added to the fabric while it is being formed. Such other materials may include, but are not limited to, fibrous organic materials such as non-wood or wood pulp such as cotton, rayon, recycled paper, pulp fluff and also super-absorbent particles. inorganic and / or organic absorbent materials, the polymeric basic fibers treated and so on. Some examples of such coform materials are described in U.S. Patents Nos. 4,100,324 to Anderson et al., 5,284,703 to Everhart et al., And 5,350,624 to Georger et al., Which are hereby incorporated in their entirety. by reference to them for all purposes.

As used here, the "water vapor transmission rate" (WVTR) generally refers to the rate at which water vapor permeates through a material as measured in units of grams per square meter per 24 hours (g / m2 / 24 hrs.). The test used to determine the water vapor transmission rate of a material can vary based on the nature of the material. For example, in some embodiments, the water vapor transmission rate can be determined in general in accordance with ASTM Standard E-96E-80. This test may be particularly appropriate for materials that are believed to have a water vapor transmission rate of up to about 3,000 grams per square meter per 24 hours. Another technique to measure the water vapor transmission rate involves the use of a PERMATRAN-W 100K water vapor permeability analysis system, which is commercially available from Modern Controls, Inc. of Minneapolis, Minnesota. Such a system may be particularly well suited for materials that are believed to have a water vapor transmission rate of greater than about 3,000 grams per square meter per 24 hours. However, as is well known in the art, other systems and techniques for measuring the water vapor transmission rate can also be used.

As used herein, the term "breathable" means permeable to water vapor and gases, but impermeable to liquid water. For example, "breathable barriers" and "breathable films" allow water vapor to pass through them, but are substantially impervious to liquid water. The "breathing capacity" of a material is measured in terms of the water vapor transmission rate (WVTR), with higher values representing a material more permeable to vapor and lower vapors that represent a material less permeable to steam. Breathable materials can, for example, have a water vapor transmission rate (WVTR) of at least about 100 grams per square meter per 24 hours (g / m2 / 24 hrs.), In some additions. from around 500 to around 20,000 grams per square meter for 24 hours, and in some additions, from around 1,000 to around 15,000 grams per square meter for 24 hours.

Detailed description Reference may now be made in detail to several embodiments of the invention, one or more examples of which are disclosed below. Each example is provided by way of explanation, not limitation of the invention. In fact, it may be apparent to those skilled in the art that various modifications and variations may be made in the present invention without departing from the scope or spirit of the invention. For example, the features illustrated or described as part of an embodiment may be used in another embodiment to still yield a further embodiment. Therefore, it is the intention that the present invention cover such modifications and variations.

The present invention is directed to a conformable thermal device that generates heat to chemical activation. The chemically activated thermal device typically contains a metal that is oxidized which is capable of experiencing an exothermic reaction in the presence of moisture and air to generate heat. Although such metals, as well as other components of the composition (e.g. carbon), are relatively inflexible and rigid, the present inventors have nevertheless discovered that one or more conformable segments can be employed to impart flexibility and formability to the thermal device. The conformable segments are malleable so that they can yield under shear stresses and acquire the shape of a surface (e.g., body part) without tearing. The conformable segments in the same manner are rigid or hard enough to substantially retain the desired shape during use.

Although not required, the conformable segments are typically formed of a non-elastic material, such as a metal. Examples of suitable metals include aluminum, copper, zinc, tin, nickel, beryllium, chromium, iron, cesium, magnesium, manganese, silicon, sodium, etc., as well as the alloys of them. For example, the conformable segments can be formed of an alloy containing about 50% by weight or more of aluminum, in some incorporations about 70% by weight or more of aluminum, and in some embodiments, from about 80% by weight. Weight up to about 99% by weight of aluminum. The claim may also contain other metal components, such as silicon, iron, copper, manganese, nickel, zinc, cesium, or tin, each of which is typically present in an amount of less. about 10% of the alloy. A particularly suitable aluminum alloy is a forged alloy available from Noranda Aluminum, Inc. of New Madrid, Missouri under the designation "8176".

The size and shape of the conformable segments can be selected to improve their ability to bend and conform to a surface. For example, the conformable segments generally have a length dimension that is substantially greater than the respective width dimension. In other words, the conformable segments have a relatively higher ratio of proportionality (eg, length to width ratio), such as from about 20 to about 400, in some embodiments from about 40 to about 200, and in some additions, from around 60 to around 100. The length dimension can also be selected to encompass around 50% or more, in some additions from around 75% to around 98%, and in some additions, from around from 80% up to about 95% of the length dimension of the thermal device to optimize the formability. The conformable segments can, for example, have a length dimension in the range from about 5 to about 100 centimeters, in some embodiments from about 10 to about 50 centimeters, and in some embodiments, from about 15 to about of 30 centimeters. In the same way, the width dimension of the conformable segments can be in the range from about 0.1 to about 20 millimeters, in some incorporations from about 0.5 to about 10 millimeters, and in some incorporations, from about 1 up to around 5 millimeters. Examples of such higher proportionality ratio segments include, without limitation, the filaments, the wires, the strips, the fibers, the rods, and the like.The conformable segments may possess any desired cross-sectional shape, such as rectangular, oval, circular, and so on. In one embodiment, for example, the conformable segments have a rectangular cross-sectional shape. Such rectangular segments may have a width dimension within the range noted above. In the same way, the thickness or height dimension of the rectangular segments is typically smaller than the width dimension to provide greater bending freedom and lower cost. For example, the height dimension may be in the range from about 0.01 to about 2 millimeters, in some additions from about 0.05 to about 1 millimeter, and in some additions, from about 0.1 to about 0.5 millimeters. Of course, the height dimension of the conformable segments need not be less than the width dimension. For circular segments, for example, the width and height dimensions may be approximately the same.

Any number of conformable segments can be employed in the thermal device of the present invention to achieve the desired degree of formability, such as from about 2 to 100, in some embodiments from 3 to 50, and in some embodiments from 5 to 15. Despite the number employed, the segments generally cooperate cooperatively, even independently. That is, the segments are able to move independently of one another, while their mechanical characteristics are cumulative as a result of the proximity of adjacent conformable segments. The independent conformable segments may be individual members or these may be segments of a single conformable member that are connected to adjacent segments at their segment ends, such as a wire bent back and forth across the width or along the length of the thermal device. In any case, the conformable segments can be bent and moved in an essentially independent manner.

The specific manner in which the conformable segments are arranged in the thermal device can also vary to improve the formability and flexibility.

In one embodiment, for example, one or more conformable segments can be arranged so that their length dimension (eg, the longest dimension) is substantially parallel to the length dimension of the thermal device. In this manner, the conformable segments and the thermal device can be bent, twisted, or rotated about the length dimension to facilitate the flexibility of the device. In the same way, one or more conformable segments can also be placed on or near the periphery of the thermal device. Of course, the conformable segments can be arranged or placed in any other location of the device, such as substantially parallel to its width dimension.

Although not required, the conformable segments are typically constrained within the chemically activated thermal device to inhibit the protrusion thereof. The segments that are formed can be constrained by adhesives, lamination, pressure, plastic cover, molding, etc. The chosen constraint is preferred, allowing some relative movement between the conformable segments and the rest of the thermal device. The movement allowed to reduce the stiffness of the product. For this purpose, the conformable segments can be incorporated into the thermal device in any of a variety of ways, depending on the manner in which the device is constructed.

The particular configuration of the thermal device is not critical to the invention. For example, the thermal device may be a "bag-in-bag" device, which typically has a small bag containing a chemical reagent that is enclosed by a larger bag containing the other reagent. The thermal device can also be a "side by side" device, which accuses a breakable seal placed between the two compartments, each of which contains one of the chemical reagents. These devices employ a strong outer seal around the perimeter of the device and a weak inner seal between the two compartments. In the chemically activated thermal devices described above, the exothermic composition generally remains unbound to a substrate. In other embodiments, however, the exothermic composition can be applied or coated on the substrate. In this regard, various embodiments of a chemically activated thermal device can now be described in more detail employing an exothermic composition coated on a substrate.

Referring to Figures 1 and 2, for example, an embodiment of a chemically activated thermal device 10 may now be described in greater detail. As shown, the thermal device 10 defines two outer surfaces 17 and 19, and is in the form of a substantially flat, conformable, and bending material. The size and the total shape of the thermal device 10 are not critical. For example, the thermal device 10 can have a shape that is generally triangular, square, rectangular, pentagonal, hexagonal, circular, and elliptical, etc. The thermal device 10 contains two (2) conformable segments 27, although of course it can be employ any number of segments in the present invention. The conformable segments 27 are arranged so that they can approximately encompass the full length of the thermal device 10 to improve its formability properties. The conformable segments 27 are also constrained with bags 26 located adjacent to the periphery 24 of the thermal device 10.

The bags 26 are generally of a shape and size sufficient to allow the movement of the conformable segments 27 to improve the flexibility of the thermal device 10. That is, the bags 26 can have dimensions of height and width greater than the respective height dimensions and width of the conformable segments 27. For example, the ratio of the width of the bags 26 to the width of the conformable segments 27 can be from about 1.0 to about 10.0, in some embodiments, from about 1.5 to about 7.5, and in some additions, from around 2.0 to around 5.0. The width of the bags 26 can, for example, be in the range of about 0.1 to about 200 millimeters, in some additions from about 1 to about 50 millimeters, and in some additions, from about 2 to about 25 mm. The proportion of the height of the bags 26 at the height of the segments 27 can similarly fall within the ranges previously noted.

The bags 26 can be formed by joining together one or more layers of thermal device 10 using any known technique, such as thermal bonding, ultrasonic bonding, adhesive bonding, sewing, etc. In the illustrated embodiment, for example, the bags 26 are formed by joining together an outer cover 36 in the regions 8 and 9. To limit access to the contents of the thermal device 10, the joined regions 9 can be located on the periphery 24 or stop only a short distance from the same, such as less than about 5 millimeters, and in some embodiments, less than about 2 millimeters from the periphery 24. The regions are joined 8 are generally separated apart from the joined regions 9 so that the width of the bags 26 is long enough to accommodate the conformable segments 27. For example, the joined regions 8 can be separated apart from the joined regions 9 by a distance of from about 1 to about 10 millimeters, in some additions from about 2 to about 10 millimeters, and in some additions, from about 3 to about 8 millimeters. In alternate embodiments, the outer cover 33 can simply be folded over the periphery 24 to define one side of the bags 26. In such embodiments, the joined regions 9 can or can not be used. Of course, it should also be understood that the conformable segments 27 can be placed in any other location of the device 10, which includes within or adjacent to any other layer of the device 10.

In addition to constricting the conformable segments 27, the outer cover 33 can also provide other beneficial properties to the thermal device. For example, the outer cover 33 defines the outer surfaces 17 and 19 of the thermal device 10 and may therefore present a smooth feeling surface., condescending, and non-irritating to the user's skin. In this aspect, the outer cover 33 may additionally include a composition that is configured to be transferred to the wearer's skin to improve the health of the skin, such as is described in U.S. Patent No. 6,149,934 issued to Krzysik and others, which is incorporated herein in its entirety by reference to the same for all purposes. The outer cover 33 can also regulate the level of humidity and / or air that penetrates the thermal device 10 to activate the exothermic reaction. For example, the outer cover 33 can be formed of materials that are permeable to liquid and vapor, impervious to liquid and permeable to vapor ("breathable"), and so forth.

In a particular embodiment, the outer cover 33 contains a breathable film, such as a monolithic or microporous film. The film can be formed of a polyolefin polymer, such as a linear low density polyethylene (LLDPE) or polypropylene. Examples of predominantly linear polyolefin polymers include, without limitation, the polymers produced from the following monomers: ethylene, propylene, 1-butene, 4-methyl-pentene, 1-hexene, 1-octene and higher olefins as well as the copolymers and the terpolymers of the previous ones. Additionally, copolymers of ethylene and other olefins include butene, 4-methyl-pentene, hexene, heptene, octene, decene, etc., are also examples of predominantly linear polyolefin polymers.

If desired, the breathable film may also contain an elastomeric polymer, such as elastomeric polyesters, elastomeric polyurethanes, elastomeric polyamides, elastomeric polyolefins, elastomeric copolymers, and so forth. Examples of elastomeric copolymers include block copolymers having the general formula ABA 'or AB, wherein A and A' each are a final block of thermoplastic polymer containing a styrenic moiety (eg, poly (vinyl arene)) and wherein B is a middle block of elastomeric polymer, such as a conjugated diene or a lower alkene polymer (e.g., polystyrene-poly (ethylene-butylene) -polystyrene block copolymers). Also suitable are polymers composed of an ABAB tetrablock copolymer, as described in U.S. Patent No. 5,332,613 issued to Taylor et al., Which is incorporated herein by reference in its entirety for all purposes An example of such a tetrablock copolymer is a styrene-poly (ethylene-propylene) -styrene-poly (ethylene-propylene) 'block copolymer ("S-EP-S-EP"). Commercially available copolymers A-B-A1 and A-B-A-B include several different formulations of Kraton Polymers of Houston, Texas under the trademark designation KRATON®. KRATON (R) block copolymers are available in several different formulations, a number of which are identified in U.S. Patent Nos. 4,663,220; 4,323,534; 4,834,738; 5,093,422 and 5,304,599, which are herein incorporated in their entirety by reference thereto for all purposes. Other commercially available block copolymers include S-EP-S or the styrene-poly (ethylene-propylene) -styrene elastomeric copolymer available from Kuraray Company, Ltd., of Okayama, Japan, under the brand name and SEPTON®.

Examples of elastomeric polyolefins include ultra low density elastomeric polypropylene and polyethylenes, such as those produced by "metallocene" or "single site" catalyst methods. Such elastomeric olefin polymers are commercially available from ExxonMobil Chemical Co. of Houston, Texas under the brand designations ACHIEVE® (propylene-base), EXACT® (ethylene-base), and EXCEED® (ethylene-base). The elastomeric olefin polymers are also commercially available from DuPont Dow Elastomers, LLC (a joint venture between DuPont and Dow Chemical Co.) under the brand designations ENGAGE® (ethylene-base) and AFFINITY®. (ethylene-base). Examples of such polymers are also described in U.S. Patent Nos. 5,278,272 and 5,272,236 issued to Lai et al., Which are hereby incorporated by reference in their entireties for all purposes. Also useful are certain elastomeric polypropylenes, such as are described in U.S. Patent Nos. 5,539,056 issued to Yang et al. And 5,596,052 issued to Resconi et al., Which are hereby incorporated by reference in their entirety. for all purposes.

If desired, mixtures of two or more polymers can also be used to form the breathable film. For example, the film can be formed from a mixture of a high performance elastomer and a low performance elastomer. A high performance elastomer is generally an elastomer having a lower level of hysteresis, such as less than about 75%, and in some embodiments, less than about 60%. In the same way, a low performance elastomer is generally an elastomer having a higher level of hysteresis, such as greater than about 75%. The hysteresis value can be determined by first lengthening a sample to an ultimate elongation of 50% and then allowing the sample to retract to an amount where the amount of resistance is zero. Particularly suitable high-performance elastomers may include styrene-based block copolymers, as previously described and commercially available from Kraton Polymers of Houston, Texas under the trademark designation KRATON®. In the same way, particularly suitable low-yield elastomers include elastomeric polyolefins, such as metallocene-catalyzed polyolefins (eg, single-site linear metallocene-catalyzed low density polyethylene) commercially available from DuPont Dow Elastomers, LLC under the brand name AFFINITY®. In some embodiments, the high-performance elastomer may constitute from about 25% by weight to about 90% by weight of the polymer component of the film, and the low-yield elastomer in the same manner may constitute from about 10%. by weight up to about 75% by weight of the polymer component of the film. Additional examples of such a low yield / high yield elastomer mixture are described in United States of America Patent No. 6,794,024 issued to Walton et al., Which is hereby incorporated by reference in its entirety for all the purposes As mentioned, the film capable of breathing can be microporous. The microporous form what is often referred to as tortuous trajectories throughout the film. The liquid that contacts one side of the film does not have a direct path through the film. Instead, a network of microporous channels in the film prevents liquids from passing, but allows gases and water vapor to pass. The microporous films can be formed of a polymer and a filler (for example, calcium carbonate). The fillers are particles or other forms of material that can be added to the film polymer extrusion mixture and that chemically does not interfere with the extruded film, but which can be uniformly dispersed throughout the film. Generally, at a dry basis weight, based on the total weight of the film, the film includes about 30% up to about 90% by weight of a polymer. In some embodiments, the film includes about 30% up to about 90% by weight of a filler. Examples of such films are described in US Pat. Nos. 5,843,057 issued to McCormack; 5,855,999 awarded to McCormack; 5,932,497 issued to Morman et al .; 5,997,981 awarded to McCormack and others; 6,002,064 granted to Kobylivker and others; 6,015,764 awarded to McCormack and others; 6,037,281 awarded to Mathis and others; 6,111,163 granted to McCormack and others; and 6,461,467 granted to Taylor and others, which are hereby incorporated in their entirety by reference thereto for all purposes.

Films are generally made breathable by stretching the filled films to create microporous paths while the polymer breaks away from the filler (e.g., calcium carbonate) during stretching. For example, the breathable material contains a stretched thin film that includes at least two basic components, for example, a polyolefin polymer and filler. These components are mixed together, heated, and then extruded into a film layer using any of a variety of processes to produce films known to those of ordinary skill in the art of processing film. Such processes for making film include, for example, die-casting, cooling and plane casting, and blown film processes.

Another type of film capable of breathing is a monolithic film that is a continuous film, non-porous, which due to its molecular structure, is capable of forming a vapor permeable barrier, impervious to liquid. Among the various polymeric films that fall into this type include films made from a sufficient amount of polyvinyl alcohol, polyvinyl acetate, ethylene vinyl alcohol, polyurethane, ethylene methyl acrylate, and ethylene methyl acrylic acid to make them with capacity to breathe. Without intending to be maintained to a particular operating mechanism, it is believed that films made of such polymers solubilize water molecules and allow the transport of those molecules from one surface of the film to the other. Therefore, these films can be sufficiently continuous, for example, non-porous, to render them substantially impervious to liquid, but still allow for vapor permeability.

Breathable films, such as those previously described, may constitute the fully breathable material, or may be part of a multi-layer film. The multilayer films can be prepared by casting or coextruding blown film, by extrusion coating, or by any conventional layering process. In addition, other breathable materials that may be suitable for use in the present invention are described in U.S. Patent Nos. 4,341,216 issued to Obenour; 4,758,239 granted to Yeo and others; 5,628,737 granted to Dobrin and others; 5,836,932 granted to Buell; 6,114,024 granted to Forte; the one of 6,153,209 granted to Vega and others; 6,198,018 granted to Curro; 6,203,810 granted to Alemany and others; and the 6,245,401 granted Ying and others, which are hereby incorporated in their entirety by reference thereto for all purposes.

If desired, the breathable film can also be attached to a nonwoven fabric, a knitted fabric, and / or a woven fabric using well known techniques. For example, appropriate techniques for joining a film to a non-woven fabric are described in US Pat. Nos. 5,843,057 to McCormack; 5,855,999, granted to McCormack; 6,002,064 granted to Kobylivker and others; 6,037,281 awarded to Mathis and others; and WO 99/12734, which are incorporated herein in their entirety by reference thereto for all purposes. For example, a non-woven laminate / breathable film can be formed into a non-woven layer and a film layer capable of breathing. The layers can be arranged so that the breathable film is bonded to the non-woven layer. In a particular embodiment, the outer cover 33 is formed from a non-woven fabric (eg, polypropylene spunbond) laminated to a breathable film.

Referring again to Figures 1 and 2, the thermal device 10 also includes a first thermal substrate 12a and a second thermal substrate 12b, which contain one or more exothermic compositions, as described below. The use of multiple thermal substrates can additionally improve the amount of heat generated by the thermal device. For example, substrates can work together to provide heat to the surface, or each can provide heat to different surfaces. Additionally, the substrates can be used that are not applied with the exothermic composition, but instead applied to a coating that simply facilitates the reaction of the exothermic composition. For example, a substrate can be used near or adjacent to the thermal substrate that includes a coating of moisture retaining particles. As previously described, moisture retaining particles can retain and release moisture to activate the exothermic reaction. It should be understood, however, that multiple thermal substrates are not required. For example, the thermal device may contain a single thermal substrate or none at all.

Examples of suitable thermal substrates may include, for example, a non-woven fabric, a woven fabric, a knitted woven fabric, a woven paper, a film, a foam, etc. When used, the non-woven fabric may include, but not limited to, spin-linked fabrics (perforated or non-perforated), meltblown fabrics, bonded carded fabrics, airlaid fabrics, coform fabrics, hydraulically entangled fabrics, and so forth. Typically, the polymers used to form the substrate material have a melting or softness temperature of from about 100 ° C to about 400 ° C, in some embodiments from about 110 ° C to about 300 ° C, and in some additions, from around 120 ° C to around 250 ° C. Examples of such polymers may include, but are not limited to, synthetic polymers (e.g., polyethylene, polypropylene, polyethylene terephthalate, nylon 6, nylon 66, KEVLAR ™, syndiotactic polystyrene, polyesters crystalline liquids, etc.); cellulosic polymers (soft wood pulp, hardwood pulp, thermomechanical pulp, etc.); the combinations thereof; and so on.

The exothermic composition can generally vary as previously indicated, but is usually capable of generating heat in the presence of moisture and oxygen. For example, the exothermic composition may contain a metal that is capable of oxidizing and releasing heat. Examples of such metals include, but are not limited to, iron, zinc, aluminum, magnesium, and so forth. Although not required, the metal can be initially supplied in powder form to facilitate handling and to reduce costs. Various methods for removing impurities from a crude metal (eg iron) to form an included powder, for example, wet processing techniques, such as solvent extraction, ion exchange, and electrolytic refining for separation of elements metallic; the processing of hydrogen gas (H2) to remove gaseous elements, such as oxygen and nitrogen; the refining method of smelting zone that floats. Using such techniques, the purity of the metal can be at least about 95 percent, at some incorporations at least about 97%, and at some incorporations, at least about 99%. The size of the metal powder particle can also be less than about 500 microns, in some embodiments less than about 100 microns, and in some embodiments, less than about 50 microns. The use of such small particles can improve the contact surface of the metal with air, thereby improving the possibility and efficiency of the desired exothermic reaction. The concentration of the metal powder employed generally can vary depending on the nature of the metal powder, and the desired extent of the exothermic reaction / oxidation. In most embodiments, the metal powder is present in the exothermic composition in an amount of from about 40% by weight to about 95% by weight, in some embodiments from about 50% by weight to about 90% by weight, and in some embodiments, from about 60% by weight to about 80% by weight.

In addition to a metal that is oxidized, a carbon component can also be used in the exothermic composition. Without intending to be limited in theory, it is believed that such a carbon component promotes the oxidation reaction of the metal and acts as a catalyst to generate heat. The carbon component can be activated carbon, carbon black, graphite, and so on. When used, activated carbon can be formed from sawdust, wood, coal, peat, lignite, bituminous coal, coconut shells, etc. Some appropriate forms of activated carbon and techniques for the formation of these are described in the patents of the United States of America Nos. 5,693,385 granted to Parks; 5,834,114 granted to Economy and others; 6,517,906 granted to Economy and others; 6,573,212 issued to McCrae et al., as well as in the United States Patent Application Requests for US Patent Nos. 2002/0141961 issued to Falat et al. and 2004/0166248 issued to Hu and others, which are incorporated herein by reference. totality by reference therein for all purposes.

The exothermic composition may also employ a binder to improve the durability of the composition when applied to a substrate. The binder can also serve as an adhesive to bond a substrate to another substrate. Generally speaking, any of a variety of binders can be used in the exothermic composition. Suitable binders may include, for example, those that become insoluble in water upon interlacing. The interlacing can be achieved in a variety of ways, including by reacting the binder with a polyfunctional interlacing agent. Examples of such entangled agents include, but are not limited to, dimethyl urea melamine-formaldehyde, urea-formaldehyde, epichlorohydrin polyamide, and the like.

In some embodiments, the latex polymer can be used as the binder. The polymer suitable for use in latexes typically has a glass transition temperature of about 30 ° C or less so that the flexibility of the resulting substrate is not substantially restricted. Moreover, the polymer typically also has a glass transition temperature of about -25 ° C or more to minimize stickiness of the latex polymer. For example, in some embodiments, the polymer has a glass transition temperature of about -15 ° C to about 15 ° C, and in some embodiments, from about -10 ° C to about 0 ° C. For example, some suitable polymer latexes that can be used in the present invention are based on polymers such as, but are not limited to, styrene-butadiene copolymers, polyvinyl acetate homopolymers, vinyl ethylene-vinyl copolymers. acetate, vinyl acetate-acrylic copolymers, ethylene-vinyl chloride copolymers, ethylene vinyl chloride-vinyl acetate terpolymers, polyvinyl acrylic chloride polymers, acrylic polymers, nitrile polymers, and any other of other suitable anionic polymer latex polymers known in the art. The loading of the polymer latexes described above can be easily varied, as is well known in the art, by using a stabilizing agent having the desired charge during the preparation of the latex polymer. The specific techniques for a latex carbon / polymer system are described in greater detail in US Pat. No. 6,573,212 issued to McCrae et al. The activated carbon / latex polymer systems that can be used in the present invention include the Nuchar® PMA, the DPX-8433-68A, and the DPX-8433-68B, all of which are available from MeadWestvaco Corp. of Stamford , Connecticut.

If desired, the latex polymer can be interlaced using any technique known in the art, such as by heat, ionization, etc. Preferably, the latex polymer is self-interlaced in which external interlaced agents (e.g. N-methylol acrylamide) are not required to induce entanglement. Specifically, the interlacing agents can lead to the formation of bonds between the latex polymer and the substrate to which it is applied. Such a union can sometimes interfere with the effectiveness of the substrate in generating heat. Therefore, the latex polymer can be substantially free of entangled agents. Particularly suitable self-crosslinked latex polymers are the ethylene-vinyl acetate copolymers available from Celanese Corp. of Dallas, Texas under the designation DUR-O-SET® Elite (e.g., PE-25220A). Alternatively, an inhibitor can simply be used to reduce the extent of interlacing, such as free-radical scavengers, methyl hydroquinone, t-butylcatechol, pH-controlling agents (eg, potassium hydroxide), etc. ..

Although latex polymers can be effectively used as binders in the present invention, such compounds sometimes result in a reduction in drapery and an increase in residual odor. Therefore, water-soluble organic polymers can also be used as binders, either alone or in conjunction with the latex polymers, to alleviate such concerns. For example, a class of water-soluble organic polymers found to be suitable in the present invention are polysaccharides and derivatives thereof. Polysaccharides are polymers containing repeated carbohydrate units, which may be cationic, anionic, nonionic, and / or amphoteric. In a particular embodiment, the polysaccharide is a nonionic, cationic, anionic, and / or amphoteric cellulosic ether. Suitable nonionic cellulosic ethers can include, but are not limited to, alkyl cellulose ethers, such as methyl cellulose and ethyl cellulose.; the hydroxyalkyl cellulose ethers, such as hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxybutyl hydroxypropyl cellulose, hydroxypropyl hydroxyethyl cellulose, hydroxybutyl hydroxyethyl cellulose and hydroxybutyl hydroxypropyl hydroxyethyl cellulose; the hydroxyalkyl alkyl cellulose ethers, such as hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, hydroxyethyl ethyl cellulose, hydroxypropyl ethyl cellulose, hydroxyethyl ethyl methyl cellulose and hydroxypropyl ethyl methyl cellulose; and so on.

Suitable cellulose ethers may include, for example, those available from Akzo Nobel of Stamford, Connecticut under the name "BERMOCOLL". Still other suitable cellulosic ethers are those available from Shin-Etsu Chemical Co. , Ltd. of Tokyo, Japan under the name "METOLOSE", which include METOLOSE Type SM (methylcellulose), METOLOSE Type SH (hydroxypropylmethyl cellulose), and METOLOSE Type SE (hydroxyethylmethyl cellulose). A particular example of a nonionic cellulosic ether is methyl cellulose which has a methoxyl substitution (DS) grade of 1.8. The degree of substitution of methoxyl represents the average number of hydroxyl groups present in each unit of anhydroglucose that has been activated, which can vary between 0 and 3. One of such cellulose ether is METOLOSE SM-100, which is a commercially available methylcellulose from Shin-Etsu Chemical Co. , Ltd .. Other suitable cellulose ethers are also available from Hercules, Inc. of Wilmington, Delaware under the name "CULMINAL".

The concentration of the carbon component and / or binder in the exothermic composition can generally vary based on the desired properties of the substrate. For example, the amount of the carbon component is generally made to the extent to facilitate the oxidation / exothermic reaction without adversely affecting other properties of the substrate. Typically, the carbon component is present in the exothermic composition in an amount of from about 0.01% by weight to about 20% by weight, in some embodiments from about 0.1% by weight to about 15% by weight, and in some additions, from around 1% by weight to around 12% by weight. Additionally, although relatively higher binder concentrations may provide better physical properties of the exothermic composition, they may similarly have an adverse effect on other properties, such as the absorption capacity of the substrate to which it is applied. Conversely, relatively lower binder concentrations can reduce the ability of the exothermic composition to remain fixed on the substrate. Therefore, in most embodiments, the binder is present in the exothermic composition in an amount from about 0.01% by weight to about 20% by weight, and in some embodiments from about 0.1% by weight to about 10% by weight, and in some embodiments, from about 0.5% by weight to about 8% by weight.

Still other components can also be employed in the exothermic composition. For example, as is well known in the art, an electrolytic salt can be employed to react with the removal of any oxide layer (s) that may otherwise prevent the metal from oxidizing. Suitable electrolyte salts may include, but are not limited to, sulfates or alkali halides, such as sodium chloride, potassium chloride, etc .; sulfates or alkali halides, such as calcium chloride, magnesium chloride, etc., and so on. When employed, the electrolytic salt is typically present in the exothermic composition in an amount of from about 0.01% by weight to about 10% by weight, and in some embodiments from about 0.1% by weight to about 8% by weight , and in some embodiments, from about 1% by weight to about 6% by weight.

Additionally, the particles can also be employed in the exothermic composition which act as moisture retainers. That is, prior to the oxidation / exothermic reaction, these particles can retain moisture.

However, after the reaction has processed to a certain extent and the moisture concentration is reduced, the particles can release moisture to allow the reaction to continue. Because acting as a moisture retainer, the particles can also provide other benefits to the exothermic composition. For example, the particles can alter the black color normally associated with the carbon component and / or the metal powder. When used, the size of the particles retaining moisture may be less than about 500 micrometers, in some embodiments less than about 100 micrometers, and in some embodiments, less than about 50 micrometers. In the same way, the particles can be porous. Without intending to be limited by theory, it is believed that the porous particles can provide a path for air and / or water vapors to better contact the metal powder. For example, the particles may have pores / channels with a mean diameter of greater than about 5 angstroms, in some incorporations greater than about 20 angstroms, and in some embodiments, greater than about 50 angstroms. The surface area of such particles may also be greater than about 15 square meters per gram, in some additions it is greater than about 25 square meters per gram, and in some additions, greater than about 50 square meters per gram. The surface area can be determined by the physical gas absorption (BET) method of Bruanauer, Emmet, and Teller, Journal of the American Chemical Society, Vol. 60, 1938, p. 309, with nitrogen as the gas of absorption.

In a particular embodiment, porous carbonate particles (eg, calcium carbonate) are used to retain moisture and also to alter the black color normally associated with activated carbon and / or metal powder. Such a color change may be more aesthetically pleasing to a user, particularly when the coating is employed in substrates designed for consumer / personal use. Suitable white calcium carbonate particles are commercially available in both dry and watery slurry forms from Omya, Inc. of Proctor, Vermont. Still other suitable inorganic particles that can retain moisture include, but are not limited to, the silicates, such as calcium silicate, alumina silicates (e.g., mica powder, clay, etc.), silicates magnesium (for example, talcum), quartzite, calcium silicate fluorite, vermiculite, etc .; the alumina; the silica; and so on. The concentration of the particles can generally vary depending on the nature of the particles, and the desired extent of the exothermic reaction and the alteration of color. For example, the particles may be present in the exothermic composition in an amount from about 0.01% by weight to about 30% by weight, in some embodiments from about 0.1% by weight to about 20% by weight, and in some additions, from around 1% by weight to around 15% by weight.

In addition to the aforementioned components, other components, such as surfactants, pH adjusters, dyes / pigments / inks, viscosity modifiers, etc., may also be included in the exothermic coating. Viscosity modifiers can be used, for example, to adjust the viscosity of the coating formulation based on the desired coating process and / or performance of the coated substrate. Suitable viscosity modifiers may include gums, such as xanthan gum. Binders such as cellulose ethers can also function as appropriate viscosity modifiers. When engaged, such additional components typically constitute less than about 5% by weight, in some embodiments less than about 2% by weight, and in some embodiments, from about 0.001% by weight to about 1% by weight of the exothermic coating.

To apply the exothermic composition to a substrate, the components can initially be dissolved or dispersed in a solvent. For example, one or more of the aforementioned components can be mixed with a solvent, either sequentially or simultaneously, to form a coating formulation that can be easily applied to a substrate. Any solvent capable of dispersing or dissolving the components is appropriate, for example water; alcohols such as ethanol or methanol; dimethylformamide; dimethyl sulfoxide; hydrocarbons such as pentane, butane, heptane, hexane, toluene and xylene; ethers such as diethyl ether and tetrahydrofuran; ketones and aldehydes such as acetone and methyl ethyl ketone; acids such as acetic acid and formic acid; and halogenated solvents such as dichloromethane and carbon tetrachloride; as well as the mixtures thereof. In a particular embodiment, for example, water is used as the solvent for a haze coating formulation to be formed. The concentration of the solvent is generally high enough to inhibit oxidation of the metal before use. Specifically, when present at a sufficiently high concentration, the solvent can act as a barrier to prevent air from prematurely contacting the metal that is oxidized. If the amount of solvent is very small, however, the exothermic reaction may occur prematurely. In the same way, if the amount of solvent is very large, the amount of metal deposited on the substrate can be very low to provide the desired exothermic effect. Although the current concentration of solvent (eg, water) employed may generally depend on the type of metal being oxidized and the substrate on which it is applied, it is typically present in an amount of about 10% by weight up to about 80% by weight, in some embodiments from about 20% by weight to about 70% by weight, and in some embodiments, from about 25% by weight to about 60% by weight of the coating formulation.

The amount of the other components added to the coating formulation can vary depending on the amount of heat desired, the wet pickup of the application method used, etc. For example, the amount of metal that is oxidized (in powder form) Within the coating formulation it is generally in the range of about 20% by weight to about 80% by weight, in some embodiments from about 30% by weight to about 70% by weight, and in some embodiments, from about 35% by weight to about 60% by weight. Additionally, the carbon component can constitute from about 0.1% by weight to about 20% by weight, in some embodiments from about 0.1% by weight to about 15% by weight, and in some embodiments, from about 0.2. % by weight to about 10% by weight of the coating formulation. Binders can range from about 0.01% by weight to about 20% by weight, in some embodiments from about 0.1% by weight to about 15% by weight and in some embodiments, from about 1% by weight to about of 10% by weight in the coating formulation. The electrolytic salts can range from about 0.01% by weight to about 10% by weight, in some incorporations from about 0.1% by weight to about 8% by weight and in some embodiments, from about 1% by weight to about 5% by weight of the coating formulation. In addition, moisture retaining particles (eg, calcium carbonate) can constitute from about 2% by weight to about 30% by weight, in some embodiments from about 3% by weight to about 25% by weight, and in some embodiments, from about 4% by weight to about 10% by weight of the coating formulation. Other components, such as surfactants, pH adjusters, viscosity modifiers, etc., can also constitute from about 0.001% by weight to about 5% by weight, in some embodiments from about 0.01% by weight to about 1% by weight, and in some embodiments from about 0.02% by weight to about 0.5% by weight of the coating formulation.

The solids content and / or viscosity of the coating formulation can be varied to achieve the desired amount of heat generation. For example, in the coating formulation it can have a solids content of from about 30% to about 80%, in some embodiments from about 40% to about 70%, and in some embodiments, from about 50% up to around 60%. By varying the solids content of the coating formulation, the presence of metal powder and other components of the exothermic composition can be controlled. For example, to form an exothermic composition with a higher level of metal powder, the coating formulation can be provided with a relatively higher solids content so that a greater percentage of the metal powder is incorporated into the exothermic composition during the process of application. Additionally, the viscosity of the coating formulation may also vary depending on the coating method and / or the type of binder used. For example, lower viscosities may be employed for saturation coating techniques (eg, submerged coating), while higher viscosities may be employed for submerged coating techniques. Generally, the viscosity is less than about 2 X 106 centipoise, in some embodiments less than about 2 X 105 centipoise, in some additions less than about 2 X 104 centipoise, and in some additions, less than about 2 X 103 centipoises, as measured with a Brookfield DV-1 viscometer with an LV rod. If desired, thickeners or other viscosity modifiers can be employed in the coating formulation to increase or decrease the viscosity.

The coating formulation can be applied to a substrate using any conventional technique, such as a bar, a roller, a knife, a curtain, the print (for example, rotogravure), spraying, and groove matrix, submerged coating, or submerged coating techniques. The materials that can form the substrate (for example, fibers) can be coated before and / or after incorporation into the substrate. The coating can be applied to one or both surfaces of the substrate. For example, the exothermic composition may be present on a surface of the substrate that is opposite that coating of the user to avoid the possibility of burning.

Additionally, the coating formulation can cover a complete surface of the substrate, or can only cover a part of the surface. When the exothermic composition is applied to multiple surfaces, each surface can be coated sequentially or simultaneously.

Regardless of the manner in which the coating is applied, the resulting thermal substrate is typically heated to a certain temperature to remove the solvent and any moisture from the coating. For example, the thermal substrate can be heated to a temperature of less than about 100 ° C, in some additions to at least about 110 ° C, and in some additions, to at least about 120 ° Cl in this manner, the resulting dry exothermic composition is anhydrous, for example, generally free of water. By minimizing the amount of moisture, the exothermic composition is less likely to react prematurely and generate heat. That is, metal, which is oxidized, generally does not react with oxygen unless something of a minimal amount of water is present. Therefore, the determined composition can remain inactive until placed in the vicinity of moisture (eg, next to a metal-containing layer) during use. It should be understood, however, that relatively small amounts of water may still be present in the thermal composition without causing a substantial exothermic reaction. In some embodiments, for example, the exothermic composition contains water in an amount of less than about 0.5% by weight, in some embodiments less than about 0.1% by weight, and in some embodiments, less than about 0.01% by weight .

The level of aggregate solids of the exothermic composition can also be varied as desired. The "level of solids aggregate" is determined by subtracting the weight of the untreated substrate from the weight of the treated substrate (after drying), dividing this weight by the weight of the untreated substrate, and then multiplying by 100%. Lower aggregate levels can optimize certain properties (eg, absorbency); while higher aggregate levels can optimize the generation of heat. And in some additions, for example, the aggregate level is from around 100% to around 5000%, in some additions from around 200% to around 2400%, and in some additions, from around 400% to around of 1200%. The thickness of the exothermic composition may also vary. For example, the thickness can be in the range from about 0.01 millimeters to about 5 millimeters, in some additions, from about 0.01 millimeters to about 3 millimeters, and in some additions, from about 0.1 millimeters to about 2 millimeters. millimeters In some cases, a relatively thin coating can be employed (eg, from about 0.01 millimeters to about 0.5 millimeters). Such as a thin coating can improve the flexibility of the substrate, while still providing uniform heat.

To maintain absorbency, porosity, flexibility, and / or other characteristic of the substrate, it may sometimes be desired to apply the exothermic composition as to cover less than 100%, in some embodiments of from about 10% to about 80%, and in some embodiments from about 20% to about 60% of the area of one or more surfaces of the substrate. For example, in a particular embodiment, the exothermic composition is applied to the substrate in a preselected pattern (e.g., a lattice pattern, a diamond-shaped grid, dots, and others). Although not required, such patterned exothermic composition can provide sufficient heating to the substrate without covering a substantial part of the surface area of the substrate. This may be desired to optimize flexibility, absorbency, or other characteristics of the substrate. It should be understood, however, that the coating can be applied uniformly to one or more surfaces of the substrate. In addition, a patterned exothermic composition may also provide a different functionality to each zone. For example, in one embodiment, the substrate is treated with two or more patterns of coated regions that may or may not overlap. The regions may be on the same or different surfaces of the substrate. In one embodiment, one region of a substrate is coated with a first exothermic composition, while another region is coated with a second exothermic composition. If desired, one region can provide a different amount of heat to that of another region.

In addition to having functional benefits, the thermal substrate can also have several aesthetic benefits as well. For example, even when it contains activated carbon, the thermal substrate can be made without the black color commonly associated with activated carbon. In one embodiment, white or light colored particles (eg, calcium carbonate, titanium dioxide, etc.) are employed in the exothermic composition so that the resulting substrate has a bluish or gray color. In addition, various pigments, dyes and / or inks can be used to alter the color of the exothermic composition. The substrate can also be applied with patterned regions of the exothermic composition to form a substrate having regions of different color.

As indicated above, moisture and oxygen are supplied to the exothermic composition to activate the exothermic composition. To provide the desired heating profile, the rate at which the moisture is allowed to come into contact with the exothermic composition is selectively controlled. Namely, if too much moisture is supplied within a given period of time, the exothermic region can produce an excessive amount of heat that overheats or burns the user. On the other hand, if very little moisture is supplied within a given period of time, the exothermic reaction may not be sufficiently activated. The desired application rate can of course be achieved by manually applying the desired amount of moisture, for example by hand or with the aid of external equipment such as a syringe. Alternatively, the thermal device itself may contain a mechanism to control the rate of moisture release.

Referring again to Figure 1, a technique for using the thermal device 10 as a mechanism to control the rate of application of moisture involves, for example, the use of a moisture-containing layer 16. It should be understood that even when shown here as having a moisture retaining layer, any number of layers (if any) can be employed in the present invention. When employed, the moisture-containing layer 16 is configured to controllably absorb and retain and release moisture to the exothermic composition over an extended period of time. The moisture-containing layer 16 can include an absorbent fabric formed using any technique such as a dry-forming technique, an air-laying technique, a carding technique, a meltblowing or spin-bonding technique, a number training, a foam forming technique, etc. In an air laying process, for example, bunches of small fibers having typical lengths ranging from about 3 to about 19 millimeters are separated and carried in an air supply and deposited on a forming grid, usually with the assistance of a vacuum supply. The randomly deposited fibers are then bonded together using, for example, hot air or an adhesive.

The moisture-containing layer 16 typically contains cellulosic fibers, such as natural and / or synthetic fluff pulp fibers. Fiber pulp fibers can be kraft pulp, sulfite pulp, thermomechanical pulp, etc. In addition, the fluff pulp fibers can include the high average fiber length pulp, the low average fiber length pulp or mixtures thereof. An example of suitable high average length fluff pulp fibers include soft wood kraft pulp fibers. Softwood kraft pulp fibers are derived from coniferous trees and include pulp fibers such as, but not limited to, softwood species from the north, west and south, including redwood, red cedar, spruce spruce, real pine, pines (for example pines of the south), false spruce (for example black spruce), combinations thereof and others. Northern softwood kraft pulp fibers can be used in the present invention. An example of commercially available south softwood kraft pulp fibers suitable for use in the present invention include those available from Weyerhaeuser Company with offices in Federal Way, Washington under the trade designation "NB-416". Another type of lint pulp that can be used in the present invention is identified with the trade designation CR 1654, available from U.S. Alliance of Childersburg, Alabama, and is a bleached highly absorbent sulphate wood pulp containing softwood pulp fibers primarily. Yet another suitable fluff pulp for use in the present invention is a bleached sulfate wood pulp containing primarily softwood fibers that are available from Bowater Corp., with offices in Greenville, South Carolina, under the trade name CoosAbsorb S pulp Low average length fibers can also be used in the present invention. An example of suitable low average length pulp fibers is hardwood kraft pulp fibers. The hardwood kraft pulp fibers are derived from deciduous trees and include pulp fibers such as, but not limited to eucalyptus, maple, birch, aspen, etc. Eucalyptus kraft pulp fibers can be particularly desired to increase softness, improve brilliance, increase opacity and change the pore structure of the sheet to increase its transmission capacity.

If desired, the moisture-containing layer 16 may also contain the synthetic fibers, such as the monocomponent fibers and the multicomponent (e.g. two component) fibers. Multicomponent fibers, for example, are fibers formed from at least two thermoplastic polymers that are extruded from separate extruders, but spun together to form a fiber. In a sheath / core multiple component fiber, a first polymer composite is surrounded by a second polymer component. The polymers of the multi-component fibers are arranged in distinct zones placed essentially constantly across the cross section of the fiber and extend continuously along the length of the fibers. Various combinations of the polymers for the multi-component fiber may be useful in the present invention, but the first polymer component typically melts at a lower temperature than the melting temperature of the second polymer component. The melting of the first polymer component allows the fibers to form a sticky skeleton structure which, when cooled, captures and agglomerates many of the pulp fibers. Typically, the polymers of such multi-component fibers are made of different thermoplastic materials, such as polyolefin / polyester bicomponent (sheath / core) fibers in which the polyolefin (eg the polyethylene sheath) melts at a temperature lower than the core (for example polyester). Exemplary thermoplastic polymers include polyolefins (e.g., polyethylene, polypropylene, polybutylene, and copolymers thereof), polytetrafluoroethylene, polyesters (e.g., polyethylene terephthalate), polyvinyl acetate, polyvinyl chloride acetate, polyvinyl butyral, acrylic resins ( for example polyacrylate, polymethylacrylate and polymethylmethacrylate), polyamides (for example nylon), polyvinyl chloride, polyvinylidene chloride, polystyrene, polyvinyl alcohol, polyurethanes, cellulosic resins (for example cellulose nitrate, cellulose acetate, cellulose acetate butyrate and ethyl cellulose) ), and copolymers of any of the above materials, such as ethylene vinyl acetate copolymers, acrylic acid-ethylene copolymers, butadiene-styrene block copolymers, and others.

The moisture-containing layer 16 may also include a super-absorbent material such as natural, synthetic and modified natural materials. The super absorbent materials are water-swellable materials capable of absorbing at least about 20 times their weight and in some cases, at least about 30 times their weight in an aqueous solution containing 0.9% by weight of sodium chloride. Examples of the synthetic super absorbent material polymers include the alkali metal and ammonium salts of poly (acrylic acid) and poly (methacrylic acid), poly (acrylamides), poly (vinyl ethers), maleic anhydride copolymers with ethers of vinyl and alpha olefins, poly (vinyl pyrrolidone), poly (vinylmorpholinone), poly (vinyl alcohol) and mixtures and copolymers thereof. Additional super absorbent materials include natural and modified natural polymers such as hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, methyl cellulose, chitosan, carboxymethyl cellulose, hydroxypropyl cellulose, and natural gums, such as alginates , xanthan gum, locust bean gum and others. In addition, mixtures of natural and fully or partially synthetic super absorbent polymers can also be used in the present invention. Other suitable absorbent gelation materials are described in U.S. Patent Nos. 3,901,236 issued to Assarsson et al .; 4,076,663 granted to Masuda and others; and 4,286,082 issued to Tsubakimoto and others, which are hereby incorporated in their entirety by reference thereto for all purposes.

When used, the super absorbent material can be from about 1% by weight to about 40% by weight, in some embodiments from about 5% by weight to about 30% by weight, and in some embodiments of from about 10% by weight to about 25% by weight of the moisture-containing layer 16 (on a dry basis). Similarly, multi-component fibers can constitute from about 1% to about 30% by weight, in some embodiments, from about 2% by weight to about 20% by weight and in some embodiments, from from about 5% by weight to about 15% by weight of the moisture-containing layer (on a dry basis). The cellulosic fibers can also constitute up to 100% by weight, in some embodiments from about 50% by weight to about 95% by weight, and in some embodiments, from about 65% by weight to about 85% by weight. weight of the layer containing moisture 16 (on a dry basis).

The rate of moisture evaporation from the moisture containing layer 16 can be controlled to achieve the desired heating profile. By controlling the rate of evaporation, the desired amount of moisture can be released into the exothermic composition within a given period of time. For example, the average moisture evaporation rate from the moisture containment layer 16 can be from about 0.05% to about 0.5%, in some embodiments from about 0.10% to about 0.25%, and in some Incorporations from around 0.15% to around 0.20% per minute. The "evaporation rate" is determined by measuring the weight of the moisture containing layer 16 at a given time and certain, subtracting this measured weight from the initial wet weight of the layer, dividing this value by the initial wet weight, and then multiplying by 100. Evaporation rates are calculated for several different times and then averaged. The evaporation rate can be determined at a relative humidity of 51% and at a temperature of around 22 ° C. It should be understood that these relative humidity and temperature conditions are the "initial" conditions in the sense that these may vary during the test due to the increased presence of water vapor in the atmosphere.

In some embodiments, the desired rate of evaporation of moisture is achieved by controlling the nature of the aqueous solution applied to the moisture containing layer 16, namely, the application of only water (vapor pressure of 23.7 mm Hg to 25 ° C) to the moisture containment layer 16 can sometimes result in too great an evaporation rate. Therefore, a solution can be added to the aqueous solution to reduce its vapor pressure, for example the tendency of water molecules to evaporate. At 25 ° C, for example, the solution can be added so that the aqueous solution added to the moisture containment layer 16 has an evaporation rate of less than 23.7 millimeters Hg, in some embodiments of less than about 23.2 millimeters Hg, and in some additions, from around 20.0 mm Hg to around 23.0 mm Hg. A particularly suitable class of solutions includes the organic and / or inorganic metal salts. The metal salts may contain monovalent (for example Na +), divalent (for example Ca2 +), and / or polyvalent cations. Examples of the preferred metal cations include cations of sodium, potassium, calcium, aluminum, iron, magnesium, zirconium, zinc and others. Examples of the preferred anions include halides, carbohydrates, sulfates, citrates, nitrates, acetates and others. Particular examples of suitable metal salts include sodium chloride, sodium bromide, potassium chloride, potassium bromide, calcium chloride, etc. The current concentration of the solution in the aqueous solution may vary depending on the nature of the solution, of the particular configuration of the thermal device, and of the desired heating profile. For example, the solution may be present in the aqueous solution in an amount of from about 0.1% by weight to about 25% by weight, in some embodiments from about 1% by weight to about 20% by weight, and in some embodiments from about 5% by weight to about 15% by weight of the solution.

In addition to controlling the aspects of the aqueous solution, the moisture containing layer 16 itself can be selectively manufactured to achieve the desired evaporation rate. For example, moisture containing layers having a relatively low density and a basis weight tend to release too much moisture in comparison to those having a higher basis weight and density. Without attempting to be bound by a theory, it is believed that such high basis weight and high density fabrics may have a lower porosity, thus making it more difficult for moisture to escape from the layer over an extended period of time. Thus, in one embodiment, the moisture containment layer 16 (for example fabric placed by air) can have a density of from about 0.01 to about 0.50, in some embodiments from about 0.05 to about 0.25, and in some embodiments, from about 0.05 to about 0.15 grams per cubic centimeter (g / cm3). The density is based on an oven-dried mass of the samples and a thickness measurement made at a load of 0.34 kilopascals (kPa) with a circular plate of 7.62 centimeters in diameter at a relative humidity of 50% and 23 ° C. In addition, the basis weight of the moisture containing layer 16 can be from about 50 to about 500 grams per square meter ("gsm"), in some embodiments from about 100 to about 300 grams per square meter and in some additions, from around 150 to around 300 grams per square meter.

Other techniques may also be employed to achieve the desired evaporation moisture rate from the moisture containment layer 16. For example, super absorbent materials are capable of swelling in the presence of an aqueous solution. The swelling increases the absorption capacity of the moisture containing layer 16, but similarly reduces the evaporation rate of the moisture since the materials exhibit a greater tendency to retain the water molecules. Therefore, the rate of evaporation can be increased to reduce the degree of swelling. One technique for reducing the degree of swelling of the super absorbent material involves reducing the temperature of the aqueous solution below room temperature, such as to less than about 25 ° C, and in some additions, from about 5 ° C. at around 20 ° C. The degree of swelling of the super absorbent material can also be reduced by incorporating one or more ionic compounds into the aqueous solution to increase its ionic strength. The ionic compounds may be the same as the solutions described above. The "ionic resistance" of a solution can be determined according to the following equation: 1 = 0 5 S Z -i m2 where , Z! the valence factor; Y my is concentration. For example, the ionic strength of a solution containing one molar of calcium and 2 molar of sodium chloride is "3" and was determined as follows: 1 = 0 5 * [(22 * 1) + (12 * 2)] = 3 Without trying to be limited by one theory, it is believed that super absorbent materials have a counter-ion atmosphere surrounding the ionic column of the polymer chains that fold when its ionic strength is increased. Specifically, the counter-ion atmosphere is made of charge ions opposite the charges along the super absorbent polymer column and are present in the ionic compound (eg, the sodium or potassium cations surrounding the distributed carboxylate anions along the column of an anionic polyacrylate polymer). By increasing the concentration of the ions that make contact with the super absorbent polymer, the gradient of concentration of ion in the liquid phase from the outside to the interior of the polymer begins to decrease and the thickness of the counter-ion atmosphere ("thickness Debye") it can be reduced from about 20 nanometers (in pure water) to about 1 nanometer or less. When the counter-ion atmosphere is highly extended, the counterions are more osmotically active and therefore promote a higher degree of liquid absorbency. On the contrary, when the concentration of ion in the absorbed liquid increases, the counter-ion atmosphere is folded and the absorption capacity is decreased. As a result of the reduction in absorption capacity, the super absorbent material exhibits a lower tendency to retain the water molecules, thus allowing their release to the exothermic composition.

Referring again to FIGS. 1-2, the breathable layers 14a and 14b may also be included within the thermal device 10 which are impervious to liquids, but permeable to gases. This allows the flow of water vapor and air to activate the exothermic reaction, but prevents an excessive amount of liquid from contacting the thermal substrate, which can either suppress the reaction or result in an excessive amount of heat overheats or burns the user. The breathable layer 14a and 14b can be formed of any breathable material, as described above. It should be understood that, while shown here as having two breathable layers, any number of breathable layers (if any) can be employed in the present invention.

The breathable layers 14a and 14b and the moisture containing layer 16 may be arranged in various ways relative to the thermal substrates 12a and 12b. In Figures 1-2, for example, the breathable layers 14a and 14b are placed directly on one side of the respective thermal substrates 12a and 12b. As a result, the breathable layers 14a and 14b can control the amount of moisture contacting the substrate 12a and 12b over a given period of time. The moisture containment layer 16 can also be placed in several locations, but this is generally positioned to help facilitate the moisture source for the thermal substrates 12a and 12b. For example, the moisture containing layer 16 can be placed between the thermal substrate 12a / the breathable layer 14a and the thermal substrate 12b / the breathable layer 14b. In this way, the amount of moisture supplied to each substrate is relatively uniform. Although not specifically illustrated, the thermal device 10 may also include several other layers. For example, the thermal device 10 may employ a thermally conductive layer to assist in distributing the heat towards a user's direction (e.g. the z-direction) and / or along the xy plane of the device 10, thereby improving uniformity of the application of heat over a selected area. The thermally conductive layer can have a thermal conduction coefficient of at least about 0.1 Watts per meter-Kelvin (W / m-K) and in some embodiments from about 0.1 to about 10 Watts per meter-Kelvin. Although any thermally conductive material can be generally employed, it is often desired that the selected material be conformable to improve the comfort and flexibility of the device 10. Suitable conformable materials include, for example, fibrous materials (e.g., non-woven fabrics). ), movies and others. Optionally, the thermally conductive layer may be permeable to gas and / or vapor so that air may contact the substrate or thermal substrates when desired to activate the exothermic reaction. One type of vapor permeable conformable material that can be used in the thermally conductive layer is a nonwoven fabric material. For example, the thermally conductive layer may contain a non-woven laminate, such as a meltblown / spunbonded ("SMS") laminate bonded laminate. Such SMS laminates can also provide a liquid transfer protection and breathability. The SMS laminate is formed by well-known methods, such as described in United States of America Patent Number 5,213,881 issued to Timmons et al., Which is hereby incorporated by reference in its entirety for all purposes. Another type of conformable and vapor permeable material that can be used in the thermally conductive layer is a breathable film. For example, the thermally conductive layer can sometimes use a nonwoven laminate / film capable of breathing.

A variety of techniques can be employed to provide conductivity to the thermally conductive layer. For example, a metallic coating can be used to provide conductivity. Suitable metals for such purposes include, but are not limited to, copper, silver, nickel, zinc, tin, palladium, lead, copper, aluminum, molybdenum, titanium, iron and others. Metal coatings can be formed on a material using any of a variety of known techniques such as vacuum evaporation, electrolytic coating, etc. For example, the patents of the United States of America number 5,656,355 granted to Cohen; 5,599,585 granted to Cohen; 5,562,994 issued to Abba and others; and 5,316,837 issued to Cohen, which are hereby incorporated in their entirety by reference thereto for all purposes, describe the proper techniques for depositing a metal coating on a material. In addition to a metal coating, still other techniques can be employed to provide conduction. For example, an additive can be incorporated into the material (e.g. fibers, films, etc.) to improve conductivity. Examples of such additives include, but are not limited to, coal fillers, such as carbon fibers and powders; metal fillers, such as copper powder, steel, aluminum powder, and aluminum flakes; and ceramic fillers, such as boron nitrate, aluminum nitrate and aluminum oxide. Commercially available examples of suitable conductive materials include, for example, the technically conductive compounds available from LNP Engineering Plastics, Inc., of Exton, Pennsylvania under the name Konduit® or Cool Polymers of Warwick, Rhode Island under the name CoolPoly® . While several examples of conductive materials have been described above, it should be understood that any thermally conductive material can be generally used in the present invention.

In addition to the thermally conductive layer, still other optional layers can be employed to improve the effectiveness of the thermal device 10. For example, an insulating layer can be used to inhibit the dissipation of heat to the outside environment so that the heat is instead focused on the patient or the user. Because the insulation layer increases the overall heat production efficiency of the device 10, the desired temperature increase can be achieved with a lower amount of exothermic coating or other reagent (e.g. moisture or oxygen). The insulation layer can have a thermal conductivity coefficient of less than about 0.1 Watts per meter-Kelvin (W / m-K), and in some additions from about 0.01 to about 0.05 Watts per meter-Kelvin. Any known insulating material can be employed in the present invention. If desired, the selected insulation material may be fibrous in nature to improve the overall conformation of the thermal device 10. The fibrous material may possess a high foaming to improve its insulating properties. Suitable high foaming materials may include porous woven materials, porous nonwoven materials, etc. Particularly suitable high-foaming materials are multi-component non-woven polymeric fabrics (for example two-component ones). For example, the multi-component polymers of such fabrics can be mechanically or chemically crimped to increase foaming. Examples of suitable high foaming materials are described in greater detail in U.S. Patent Nos. 5,382,400 issued to Pike et al .; 5,418,945 issued to Pike and others; and 5,906,879 issued to Huntoon and others, which are incorporated herein in their entirety by reference thereto for all purposes. Still other materials suitable for use as an insulation material are described in US Pat. No. 6,197,045 issued to Carson which is hereby incorporated by reference in its entirety for all purposes.

As noted above, the various layers and / or components of the thermal device 10 can be assembled together using any suitable and known attachment mechanism such as adhesive, ultrasonic, thermal bonds, etc. Suitable adhesives may include, for example, hot melt adhesives, pressure sensitive adhesives and others. When used, the adhesive can be applied as a uniform layer, such as a patterned layer, a spray pattern or any separate line, swirls or dots. In some embodiments, the exothermic composition can serve the dual purposes of generating heat and also acting as the adhesive. For example, the binder of the exothermic composition can join together one or more layers of the thermal device 10.

Although various configurations of the thermal device have been described above, it should be understood that other configurations are also included within the scope of the present invention. For example, other layers may also be employed to improve the exothermic properties of the thermal device. For example, the substrate can be used near or to one side of the thermal substrate that includes a coating of moisture retaining particles. As described above, the moisture retention particles can retain and release moisture to activate the exothermic reaction. Furthermore, of a particular benefit, one or more of the aforementioned layers can achieve multiple functions of the thermal device. For example, in some embodiments, the breathable layer, the moisture retention layer, etc., may be coated with an exothermic composition and thus also serve as a thermal substrate. Although not expressly stated here, it should be understood that numerous other possible combinations and configurations are well within the ordinary skill and those skilled in the art.

Moisture can be applied at any time before or during the use of the thermal device, such as just before use or during manufacture. For example, water may be applied previously to the moisture containment layer as described above. The moisture is added in an amount effective to activate an exothermic, electrothermal reaction between the electrochemically oxidizable element (e.g., the metal powder) and the electrochemically reducible element (e.g., oxygen). Even though this amount may depend on the reaction conditions and the amount of heat desired, the moisture is typically added in an amount of from about 20% by weight to about 500% by weight, and in some embodiments, from about from 50% to about 200% by weight of the weight of the amount of oxidizable metal present in the coating. Although not necessarily required, it may be desired that such thermal water treatment devices within a material essentially impermeable to liquid (vapor permeable or vapor impermeable) that inhibits the exothermic composition of sufficient oxygen contact to prematurely activate the reaction Exothermic To generate heat, the thermal device is simply removed from the package and exposed to air.

Certain aspects of the thermal device can be optimized to supply a controlled amount of moisture and / or oxygen to the exothermic composition during use. Through selective control over the supply of these reagents, a heating profile can be achieved in which a high temperature is quickly reached and maintained over an extended period of time. For example, a high temperature of from about 30 ° C to about 60 ° C, in some additions from about 35 ° C to about 55 ° C, and in some additions from about 37 ° C to about of 43 ° C, can be achieved in 20 minutes or less, and in some additions, 10 minutes or less. This elevated temperature can be maintained substantially at least for about 1 hour, in some additions for at least about 2 hours, and in some embodiments for at least about 4 hours, and in some embodiments at least around of 10 hours (for example for use during the night).

The thermal device of the present invention can be employed in a wide range of articles to provide a heating effect. For example, the thermal device can be used as a heating pad, bandage, food warmer, animal warmer, water heater and others. The thermal device can also be used to deliver heat in various other applications, such as covers or blankets to warm patients during surgical or medical procedures.

The present invention can be better understood with reference to the following examples.

EXAMPLE 1 The ability to form a thermal device was demonstrated. Initially, pieces (7 inches by 12.5 inches) of a carded and bonded woven fabric were provided having a basis weight of 0.9 ounces per square yard. The fabric was formed from a mixture of 75% by weight of bicomponent fibers and 25% by weight of polyester fibers. The bicomponent fibers were obtained from Fibervisions, Inc., of Covington, Georgia under the name "ESC 215", which had a polyethylene shell and a polypropylene core, a denier of 3.0, and 0.55% by weight of finished " HR6". The polyester fibers were obtained from Invista of Wichita, Kansas under the name "T-295", which had a denier of 6.0 and contained 0.5% by weight of the Ll finish.

The coating formulation was prepared as follows. In a 400 mL pyrex beaker, 5.0 grams of METOLOSE SM-100 (Shin-Etsu Chemical Co., Ltd.) and 12.5 grams of sodium chloride (Mallinckrodt) were added to 150.0 grams of distilled water that was stirred and heated at 69 ° C. The mixture was stirred and allowed to cool when the following additional ingredients were added sequentially: 17.3 grams of emulsion of vinyl acetate-ethylene DUR-O-SET® Elite PE 25-220A (Celanese Emulsions), 39.7 grams of carbonate solution of Calcium shows XC4900 # 04.1919704 (Omya), 15.0 grams of Nuchar SA-20 activated charcoal (MeadWestvaco), and 170.0 grams of A-131 iron powder (North American Hóganás). After about 30 minutes of stirring the formulation with all the ingredients, the temperature was reduced with an ice bath of from about 23 ° C to about 18 ° C. A noticeable increase in viscosity occurred when the temperature reached around 20 ° C. The viscosity of the formulation was measured at 2,538 cP (Brookfield viscometer, spindle LV-4 at 100 revolutions per minute). The calculated concentration of each component of the aqueous formulation is stated below in Table 1.

Table 1: Components of the Aqueous Formulation The aqueous formulation was applied to one side of the 0.9 oz. Pieces of fabric per square yard using a single # 60 rolled coiled rod. The coated pieces were dried in an oven for about 15 minutes at 110 ° C. The concentration of the components of the exothermic composition was then calculated from the coated and dried cloth pieces (16.4 + 0.4 grams), the untreated pieces of cloth (1.9 ± 0.1 grams), and the composition of the aqueous formulation. The results are set down in table 2.

Table 2: Components of the Exothermic Composition A 7-layer structure (3.5 inches x 4 inches) was then designed for the activation of the exothermic reaction. Specifically, the 7-layer structure included three of the coated fabric pieces placed on one side of the moisture containing layer, and the other three coated fabric pieces placed on the other side of the moisture containing layer. The uncoated side of the fabric pieces faced the moisture retention layer. The total weight of the 6 layers of the coated fabric was 15.4 grams (10.2 grams of iron). The moisture containment layer was formed of 75% by weight of wood pulp fluff, 15% by super absorbent weight, and 10% by weight of KoSa T255 bicomponent fiber. The moisture containment layer had a basis weight of 225 grams per square meter and a density of 0.12 grams per cubic centimeter. The pulp of wood pulp was obtained from Weyerhaeuser under the trade name "NB416". The super absorbent was obtained from Degussa AG under the name "SXM 9543".

Before forming the multi-layer structure, each side of the moisture containment layer (2.2 grams) was moistened by water spraying (6.6 grams in an amount that increased the layer's mass by a factor of 4.0). 7 layers was then placed inside a rectangular bag (4 inches x 4.5 inches) made of a laminated microporous film bonded with nylon yarn.The laminate was obtained from Mitsubishi International Corp., and Type TSF EDFH 5035 was marked. Water vapor transmission of the laminate was measured at 455 grams per square meter per 24 hours using the cup method (ASTM standard E-96E-80) .The bag was sealed with metallized tape obtained from Nashua.

Although not specifically carried out in this example, the present inventors contemplated additional examples in which the aforementioned thermal device can employ conformable segments. For example, the bag may contain two pieces of flat heat-sealed wire within the respective bags, as shown in Figure 1. A suitable flat wire may be obtained from Noranda Aluminum, Inc., under the designation 8176 alloy. / EEE.

EXAMPLE 2 A thermal device was formed as described in example 1, except that it was heat sealed in a metallized storage bag for 16 hours before the activation of the reaction. The metallized storage bag was KAL-ML5 from Kapak Corporation, a two-layer structure containing a metallized polyester layer that was adhesively laminated to a linear low density polyethylene film. The total amount of six layers of coated cloth was 14.8 grams (9.8 grams of iron). The moisture containment layer (2.1 grams) was wet on both sides by spraying water (6.2 grams) in an amount that increased the layer's mass by a factor of 3. 9.

EXAMPLE 3 A coating formulation similar to that described in Example 1 was prepared and applied to one side of a carded and bonded fabric of 0.9 ounces per square yard in the same manner as described in Example 1. The calculated concentration of each component of the aqueous formulation is set out below in Table 3.

Table 3: Components of the Aqueous Formulation The concentration of the components of the exothermic composition was calculated from the coated and dried cloth pieces (11.6 ± 0.3 grams), the untreated cloth pieces (1.6 ± 0.1 grams) and the composition of the aqueous formulation. The results are set down in table 4.

Table 4: Components of the Exothermic Composition A thermal device (3 inches by 8 inches) with a seven-layer structure was then designed to activate the exothermic reaction. The thermal device was sealed with heat in the middle to produce a segmented device with two equal sections (3 inches by 4 inches). The size of the 7-layer components that was placed in each section was 2.5 inches by 3.5 inches. The total weight of the six coated layers was 8.3 grams (5.2 grams of iron) for one section and 8.6 grams (5.4 grams of iron) for the other section. In addition, 3.9 grams of an aqueous salt solution was applied to the moisture containing layer of the first section and 4.0 grams of the solution was applied to the second section. The salt solution containing 9.9% by weight of sodium chloride in water, and increased the mass of the moisture containing layer of both sections by a factor of 4.0. The seven-layer structure was placed inside a laminated bag of microporous film bonded with nylon yarn (described in Example 1) (segmented into two equal sections as described above) and the edges of the bag were heat sealed. The resulting thermal device was heat sealed in a metallized storage bag for 44 hours prior to activation of the reaction.

Although not specifically carried out in this example, the present invention contemplates additional examples in which the aforementioned thermal device can employ conformable segments as described in example 1.

EXAMPLE 4 A segmented thermal device was formed as described in Example 3, except that the total weight of the six coated layers was 8.2 grams (5.2 grams of iron) for one section and 8.9 grams (5.6 grams of iron) for the other section . In addition, 4.1 grams and 4.0 grams of an aqueous salt solution were applied to the moisture containment layer of the first and second sections respectively. The salt solution contained 9.9% by weight of sodium chloride in tap water, and the mass of the moisture retention layer of the first and second sections was increased by a factor of 3.9 and 3.8 respectively. The resulting thermal device was heat sealed in a metallized storage bag for 189 hours before the activation of the reaction.

EXAMPLE 5 The ability to achieve a controlled heating profile using a thermal device of the present invention was demonstrated. Specifically, the thermal devices of Examples 1-4 were tested. Because Example 1 was not sealed in the metallized storage bag, it was tested immediately after training. For Examples 2-4, the metallized storage bag was opened to initiate the reaction. The test was carried out by attaching a wired thermocouple to a data collection device on one side of the thermal device. For the segmented thermal devices described by examples 3-4, both sections were tested. The temperature was recorded as a function of time (at intervals of 5 seconds) to give the thermal response curves shown in Figure 3. The results are shown for only a segment of the devices described by Examples 3-4. The thermal response curve for the other segment of the device of Example 3 was similar to the first segment (1-2 ° C warmer), while the other segment of the device of Example 4 was around 6-8 ° C warmer , more likely due to the higher iron content. As illustrated, the thermal response curves for the samples of Examples 3-4 (applied with an aqueous salt solution) reached 38 ° C within about 10 minutes after the opening of the storage bag, and also remained from 38 to 42 ° C for at least 3 hours.

EXAMPLE 6 The ability to form a thermal device according to the invention was demonstrated. A coating formulation similar to that described in Example 3 was prepared, but a higher level of sodium chloride was used. The coating formulation was applied to one side of the carded and bonded fabric of 0.9 ounces per square yard in the same manner as described in Example 1. The calculated concentration of each component of the aqueous formulation is set forth below in Table 5.

Table 5: Components of the Aqueous Formulation The concentration of the components of the exothermic composition was calculated from the piece of coated and dried cloth (16.3 grams), the untreated piece of cloth (1.9 grams) and the composition of the aqueous formulation. The results are set down below in table 6.

Table 6: Components of the Exothermic Composition A thermal device (4 inches by 4.5 inches) with a seven-layer structure was then designed to activate the exothermic reaction. The thermal device was formed as described in Example 1, with the size of the seven-layer components also being 3.5 inches by 4 inches. The total weight of the six coated layers was 15.6 grams (9.4 grams of iron). In addition, each side of the moisture containment layer (2.2 grams) was wetted by spraying 6.1 grams of water in an amount that increased the layer's mass by a factor of 3.8. The seven-layer structure was placed inside a laminated bag of microporous film bonded with nylon yarn (described in Example 1) and the edges of the bag were sealed with metallized tape obtained from Nashua. The resulting thermal device was heated and sealed in a metallized storage bag for 20 hours before activation of the reaction.

Although not specifically performed in this example, the present inventors contemplate additional examples in which the aforementioned thermal device can employ conformable segments, as described above in Example 1.

EXAMPLE 7 A thermal device was formed as described in Example 1, except that a "separation layer" was used to separate the moisture containing layer from the three coated layers on each side. The separation layer was a film / fabric laminate with small perforated holes to allow steam and gas to pass while preventing the passage of the liquid. This was obtained from Tredegar Film Products with the label FM-425 lot number SHBT040060. Each side of the moisture containment layer (2.2 grams) was wetted with spraying 6.3 grams of water in an amount that increased the layer's mass by a factor of 3.9. Then the separation layer was placed around it with the fabric side of the separation layer in contact with the wet moisture containment layer. The three coated layers were then placed on each side with the uncoated side in contact with the film side of the separation layer. The total weight of the six coated layers was 14.2 grams (9.2 grams of iron). The nine layer structure was then placed inside a laminated bag of microporous film bonded with nylon yarn (described in Example 1) and the edges of the bag were sealed with metallized tape, obtained from Nashua. The resulting thermal device was sealed with heat in a metallized storage bag for 20 hours before activation of the reaction.

Although not specifically carried out in this example, the present inventors contemplate additional examples in which the aforementioned thermal device can employ conformable segments as described in example 1.

EXAMPLE 8 A thermal device was formed as described in Example 7, except that the six coated layers contained a lower level of sodium chloride. The calculated concentration of each component of the aqueous formulation that was used to coat one side of the carded and bonded fabric of 0.9 ounces per square yard to produce the coated layers is set forth in Table 7.

Table 7: Components of the Aqueous Formulation The concentration of the components of the exothermic composition was then calculated from the piece of coated and dried cloth (16.1 grams), the piece of untreated cloth (1.9 grams) and the composition of the aqueous formulation. The results are set down in table 8 below.

Table 8: Components of the Exothermic Composition A nine layer structure (3.5 inches by 4 inches) as described in example 7 was then designed to activate the exothermic reaction. The moisture containment layer (2.1 gram) was wet on both sides with sprinkling of 6.0 grams of water in an amount that increased the mass of the layer by a factor of 3.8. The total weight of the six coated layers was 15.6 grams (10.7 grams of iron). The nine layer structure was placed inside a laminated bag of microporous film bonded with nylon yarn (described in Example 1) and the edges of the bag were sealed with a metallized tape obtained from Nashua. The resulting thermal device was sealed with heat in a metallized storage bag for 20 hours before activation of the reaction.

Although not specifically carried out in this example, the present inventors contemplate additional examples in which the aforementioned thermal device can employ conformable segments as described in Example 1.

EXAMPLE 9 A thermal device was formed as described in Example 8 except that the moisture containing layer contained an aqueous salt solution instead of water. further, 6.0 grams of the aqueous salt solution was applied to the moisture containment layer (2.2 grams) by spraying both sides, an amount that increased the layer's mass by a factor of 3.7. The salt solution contained 10.0% by weight of sodium chloride in distilled water. The total weight of the six coated layers was 15.5 grams (10.7 grams of iron). The resulting thermal device was sealed with heat and in a metallized storage bag for 20 hours before activating the reaction.

EXAMPLE 10 The ability to achieve a controlled heating profile using a thermal device of the present invention was demonstrated. Specifically, the thermal devices of Examples 6-9 were tested. The metallized storage bag was opened to initiate the reaction. The test was carried out by attaching a wired thermocouple to a data collection device on one side of the thermal device. The temperature was recorded as a function of time (at intervals of 5 seconds) to give the thermal response curves shown in Figure 4.

As shown in Figure 4, the sample of Example 9 (moisture-containing layer contains an aqueous salt solution) provided a rapid heating rate (temperature to at least 38 ° C within about 10 minutes) after opening the storage bag. The sample of Example 8 (the moisture retaining layer contains water) provided a slower heating rate. However, the samples of Examples 8 and 9 which contained an exothermic composition with less salt, provided higher temperature thermal response curves compared to the samples of Examples 6 and 7 which contained higher levels of salt in the exothermic composition of the coated fabrics. Therefore, it appears that the composition of the liquid in the moisture-containing layer in the exothermic coating composition can be used to control the heating profile of the thermal device. More specifically, the salt content in both compositions can be adjusted to obtain the desired heating profile.

EXAMPLE 11 The ability to form a thermal device was demonstrated. A coating formulation similar to that described in Example 6 was prepared, but sodium chloride was not used. The coating formulation was applied to one side of the carded and bonded fabric of 0.9 ounces per square yard in the same manner as described in Example 1. The calculated concentration of each component of the aqueous formulation is set forth in Table 9 below.

Table 9: Components of the Aqueous Formulation The concentration of the components of the exothermic composition was calculated from the piece of coated and dried cloth (14.9 grams), the untreated piece of cloth (2.0 grams) and the composition of the aqueous formulation. The results are set down below in table 10.

Table 10: Components of the Exothermic Composition A thermal device (4.25 inches by 4.5 inches) with a nine-layer structure was then designated to activate the exothermic reaction. The thermal device was formed as described in Example 7 with the size of the nine-layer components being 3.5 inches by 4 inches. The total weight of the six coated layers was 13.9 grams (9.2 grams of iron). In addition, each side of the moisture containment layer (2.4 grams) was wetted by spraying 6.7 grams of water, an amount that increased the layer's mass by a factor of 3.8. The nine layer structure was placed inside a laminated bag of microporous film bonded with nylon yarn (described in Example 1) and the edges of the bag were sealed with metallized tape obtained from Nashua. The resulting thermal device was heat sealed in a metallized storage bag for 19.5 hours before the activation of the reaction.

Although not specifically carried out in this example, the present inventors contemplate additional examples in which the aforementioned thermal device can employ conformable segments, as described in example 1.

EXAMPLE 12 A thermal device was formed as described in Example 11, except that the moisture containing layer (2.2 grams) was wet on both sides with spraying 6.2 grams of an aqueous salt solution, an amount that increased the mass of the layer by a factor of 3.8. The salt solution contained 10% by weight of sodium chloride in distilled water. The total weight of the six coated layers was 13.7 grams (9.1 grams of iron). The resulting thermal device was heat sealed in a metallized storage bag for 19.5 hours before the activation of the reaction.

EXAMPLE 13 A thermal device was formed as described in Example 7, except that the moisture containing layer (2.2 grams) was wet on both sides with spraying 6.0 grams of an aqueous salt solution, an amount that increased the mass of the layer by a factor of 3.7. The salt solution contained 10% by weight of sodium chloride in distilled water. The thermal device was also slightly larger than Example 7 at 4.25 inches by 4.5 inches. The total weight of the six coated layers was 14.6 grams (9.6 grams of iron). The 9-layer structure was then placed inside a laminated bag of microporous film bonded with yarn (described in Example 1) and the edges of the bag were sealed with metallized tape, obtained from Nashua. The resulting thermal device was heat sealed in a metallized storage bag for 18 hours before activating the reaction.

Although not specifically carried out in this example, the present inventors contemplate additional examples in which the aforementioned thermal device can employ conformable segments, as described in example 1.

EXAMPLE 14 A thermal device was formed as described in example 9. In addition, the moisture containing layer (2.2 grams) was wet on both sides by spraying 6.1 grams of an aqueous salt solution, an amount that increased the mass of the layer by a factor of 3.8. The salt solution contained 10.0% by weight of sodium chloride in distilled water. The total weight of the six coated layers was 16.6 grams (11.4 grams of iron). The resulting thermal device was heat sealed in a metallized storage bag for 18 hours before activating the reaction.

EXAMPLE 15 The ability to achieve a controlled heating profile using a thermal device of the present invention was demonstrated. Specifically, the thermal devices of Examples 11-14 were tested. The metallized storage bag was opened to initiate the reaction. The test was carried out by attaching a thermocouple wire to a data collection device on one side of the thermal device. The temperature was recorded as a function of time (at intervals of 5 seconds) to give the thermal curves shown in Figure 5.

EXAMPLE 16 The ability to form a thermal device was demonstrated. Initially, a 7 inch wide roll of a carded and bonded woven fabric was provided having a basis weight of 1.5 ounces per square yard (50 grams per square meter). The fabric was formed from a mixture of 60% by weight of bicomponent fibers and 40% by weight of polyester fibers. The bicomponent fibers were obtained from FiberVisions, Inc., of Covington, Georgia under the name "ESC 215", which had a polyethylene sheath and a polypropylene core, a denier of 1.5, and 0.55% by weight of a finished "HR6". The polyester fibers were obtained from Invista of Wichita, Kansas under the name "T-295", which had a denier of 6.0 and contained 0.5% by weight of finished Ll.

The coating formulation was prepared as follows. In a one-gallon metal bucket, 34.5 grams of METOLOSE SM-100 (Shin-Etsu Chemical Co., Ltd.) and 25.0 grams of sodium chloride (Mallinckrodt) were added to 1172.0 of distilled water which was stirred and heated at 68 ° C. The mixture was stirred and allowed to cool when the following additional ingredients were added sequentially: 139.6 grams of DUR-O-SET® Elite PE 25-220A ethylene-vinyl acetate emulsion (Celanese Emulsions), 330.2 grams of XP-5200- 6 sample # 05.2435503 calcium carbonate (Omya), 60.1 grams of Nuchar SA-400 activated carbon (MeadWestvaco), and 1181.1 grams of A-131 iron powder (North American Hóganás). After about 30 minutes of stirring the formulation with all the ingredients, the temperature was reduced with an ice bath at about 10 ° C. A noticeable increase in viscosity occurred when the temperature was reduced. The calculated concentration of each component of the aqueous formulation is stated below in Table 11.

Table 11: Components of the Aqueous Formulation The aqueous formulation was applied to one side of the fabric of 1.5 ounces per square yard in a pilot line process using a knife coater. The separation between the blade and the steel roller that carried the fabric was set to 900 microns. The line speed was 0.25 meters per minute. The pilot line coater contained a 4-foot dryer set at 145 ° C which was used to partially dry the coated fabric. The partially dried coated fabric was cut into 17 inch pieces and placed in a laboratory oven at 110 ° C for about 20 minutes to complete the drying step. The concentration of the components of the exothermic composition was calculated from the coated and dried cloth pieces (56.5 ± 1.5 grams), the piece of untreated cloth (4.3 grams) and the composition of the aqueous formulation. The results are set down in table 12 below.

Table 12: Components of the Exothermic Composition A five-layer structure (1.6 inches by 8 inches) was designed to activate the exothermic reaction. Specifically, the five layer structure included one of the coated fabric pieces placed on one side of the moisture coating layer, and the other piece of coated fabric placed on the other side of the moisture containment layer. The uncoated side of the fabric pieces faced the moisture-containing layer. The moisture-containing layer was formed of 90% by weight of wood pulp fluff (Weyerhaeuser NF401) and 10% by weight of KoSa T255 bicomponent fiber. The layer containing moisture had a basis weight of 175 grams per square meter and a density of 0.8 grams per cubic centimeter. A "separation layer" was used to separate the moisture-containing layer from the coated layer on each side. The separation layer was a fabric / film laminate with small perforated holes to allow the passage of vapor and gas while preventing the passage of liquid. This was obtained from Tredegar Film Products with the label FM-425 lot number SHBT040060.

Before forming the multi-layered structure, the layer containing moisture (1.5 grams) was wet on each side with spraying 4.2 grams of distilled water, an amount that increased the layer's mass by a factor of 3.8. Then the separation layer was placed around it with the fabric side of the separation layer in contact with the layer containing wet moisture. A coated layer was then placed on each side with the uncoated side in contact with the film side of the separation layer. The total weight of the two coated layers was 13.5 grams (9.9 grams of iron). The five-layer structure was then placed inside a bag (3 inches by 9 inches) that was sealed with the heat sealant. The bag was made of a laminated microporous film bonded with nylon yarn (described in Example 1) which had a layer of short weave fabric sealed with heat on the side bonded with nylon spinning. The short woven fabric was produced from 20% wood pulp fluff (50% North softwood kraft fibers / 50% softwood kraft bleached Alabama pine), 58% 1.5 denier polyester fiber (Invista Type 103), and 22% bonded with polypropylene yarn (Kimberly-Clark Corp.).

The bag was made by folding a 6-inch by 9-inch piece of the materials described above in half to produce the size of 3 inches by 9 inches. A flat wire that measured approximately 8.5 inches (21.59 centimeters) in length, 2.4 millimeters in width and 0.24 millimeters in thickness was then placed inside and against the bend. The wire was obtained from Noranda Aluminum, Inc., with the designation of Alloy 8176 / EEE. A bag of approximately 9.525 millimeters wide and 22.86 centimeters long was formed around the wire by settling with heat from the upper part to the bottom of the bag. A second flat wire with the same characteristics as the first wire was then placed on the other edge of the bag. A second bag of approximately 9.525 millimeters wide and 22.86 centimeters long was formed around the second wire by heat sealing the upper part to the bottom of the bag along the outer edge and 9.525 millimeters from the outer edge.

EXAMPLE 17 A thermal device was formed as described in Example 16, except that the moisture-containing layer contained an aqueous salt solution instead of tap water. In addition, 4.3 grams of the aqueous salt solution was applied to the moisture containment layer (1.5 grams), an amount that increased the layer's mass by a factor of 3.8. The salt solution contained 10.0% by weight of sodium chloride in distilled water. The total weight of the two coated layers was 13.7 grams (10.1 grams of iron). The resulting thermal device was heat sealed in a metallized storage bag for 8 days prior to activation of the reaction.

EXAMPLE 18 A thermal device was formed as described in Example 16, except that the moisture-containing layer was formed of 75% by weight of wood pulp fluff (Weyerhaeuser NB416), 15% by weight of super absorbent (Degussa SXM9543), and 10% by weight of KoSa T255 bicomponent fiber, and had a basis weight of 225 grams per square meter and a density of 0.12 grams per cubic centimeter. The moisture-containing layer also contained an aqueous salt solution instead of tap water; 5.8 grams of the aqueous salt solution were applied to the layer containing moisture (2.2 grams) and an amount that increased the layer's mass by a factor of 3.7. The salt solution contained 10.0% by weight of sodium chloride in distilled water. The total weight of the two coated layers was 14.6 grams (10.7 grams of iron). The resulting thermal device was heat sealed in a metallized storage bag for 66 hours before activating the reaction.

EXAMPLE 19 A thermal device was formed as described in Example 16, except that the moisture-containing layer was formed from the material described in Example 18. The layer containing the moisture was also contained in an aqueous salt solution instead of water from the key; 6.0 grams of the aqueous salt solution were applied to the layer containing moisture (2.1 grams), an amount that increased the layer's mass by a factor of 3.8. The salt solution contained 10.0% by weight of sodium chloride in distilled water. The total weight of the two coated layers was 14.7 grams (10.8 grams of iron). The resulting thermal device was heat sealed in a metallized storage bag for 66 hours before the activation of the reaction.

EXAMPLE 20 The ability to achieve a controlled heating profile using a thermal device of the present invention was demonstrated. Specifically, the thermal devices of examples 16-19 were tested. The metallized storage bag was opened to initiate the reaction. The test was carried out by attaching a wired thermocouple to a data collection device on one side of the thermal device. The temperature was recorded as a function of time (at intervals of 5 seconds) to give the thermal curves shown in Figure 6.

As shown in Figure 6, the thermal response curves for the samples of Examples 17-19 showed a rapid heating rate (temperature of at least 38 ° C within about 10 minutes) and a temperature profile elevated for an extended period of time. These samples contained salt both in the exothermic composition and in the liquid contained by the moisture containment layer. In addition, a moisture containing layer that did not contain super absorbent was used for the sample of Example 17 and the thermal response curve was similar to the curves for the samples of Examples 18 and 19. Note in Figure 6 that the curve of thermal response for the sample of Example 16 did not show a rapid heating rate and the temperature only reached around 30 ° C. This sample only contained water in the moisture containment layer.

EXAMPLE 21 The ability to form a thermal device according to the invention was demonstrated. The coated fabric described in Example 16 was used in a five-layer structure (2.5 inches by 7 inches) to activate the exothermic reaction. Specifically, the five layer structure included one of the coated fabric pieces placed on one side of the moisture containment layer, and another piece of coated fabric placed on the other side of the moisture containment layer. The uncoated side of the fabric pieces faced the moisture containment layer. The moisture containment layer was formed of 75% by weight of wood pulp fluff, 15% by super absorbent weight, and 10% by weight of KoSa T255 bicomponent fiber. The moisture-containing layer had a basis weight of 225 grams per square meter and a density of 0.12 grams per cubic centimeter. The pulp of wood pulp was obtained from Weyerhaeuser under the name "NB426". The super absorbent was obtained from Degussa AG under the name "SXM 9543". A "separation layer" was used to separate the layer containing moisture from the coated layer on each side. The separation layer was a cloth / film laminate with those holes drilled to allow vapor and gas to pass while preventing the passage of the liquid. This was obtained from Tredegar Film Products with the label FM-425 lot number SHBT040060.

Before forming the multi-layer structure, the moisture-containing layer (2.7 grams) was wet on each side by spraying 7.6 grams of an aqueous salt solution, an amount that increased the mass of the layer by a factor of 3.8. The salt solution contained 3.0% by weight of sodium chloride in distilled water. Then the separation layer was placed around it with the fabric side of the separation layer in contact with the wet moisture containment layer. A coated layer was then placed on each side with the uncoated side in contact with the film side of the separation layer. The total weight of the two coated layers was 18.1 grams (13.3 grams of iron). The five-layer structure was then placed inside the bag (3.2 inches by 8 inches) that was sealed with a heat sealer. The bag was made of a laminated microporous film bonded with nylon yarn (described in Example 1) that had a short weave fabric heat sealed to the side bonded with nylon spinning. The short-woven fabric was produced from 20% wood pulp fluff (50% kraft softwood fibers from North / 50% softwood kraft bleached Alabama pine fibers), 58% polyester fiber from 1.5 denier (Invista type 103), and 22% bonded with polypropylene yarn (Kimberly-Clark Corporation). The resulting thermal device was sealed with heat in a metallized storage bag for 64 hours before activating the reaction.

Although not specifically carried out in this example, the present inventors contemplated additional examples in which the above reference thermal device can employ conformable segments, as described in example 1.

EXAMPLE 22 A thermal device was formed as described in Example 21. The moisture containment layer (2.7 grams) contained 7.2 grams of aqueous salt solution, an amount that increased the layer mass by a factor of 3.7. The salt solution contained 3.0% by weight of sodium chloride in distilled water. The total weight of the two coated layers was 17.1 grams (12.5 grams of iron). The resulting thermal device was sealed with heat in a metallized storage bag for 64 hours before activating the reaction.

EXAMPLE 23 A thermal device was formed as described in example 21. The layer containing the moisture (2.7 grams) contained 7.6 grams of an aqueous salt solution, an amount that increased the mass of the layer by a factor of 3. 8. The salt solution contained 3.0% by weight of sodium chloride in distilled water. The total weight of the two coated layers was 17.3 grams (12.6 grams of iron). The resulting thermal device was sealed with heat in a metallized storage bag for 64 hours before activating the reaction.

EXAMPLE 24 A thermal device was formed as described in Example 21. The moisture containment layer (2.7 grams) contained 7.2 grams of an aqueous salt solution, an amount that increased the mass of the layer by a factor of 3.7. The salt solution contained 3.0% by weight of sodium chloride in distilled water. The total weight of the two coated layers was 18.0 grams (13.2 grams of iron). The resulting thermal device was sealed with heat in a metallized storage bag for 64 hours before activating the reaction.

EXAMPLE 25 The ability to achieve a controlled heating profile was demonstrated using a thermal device of the present invention. Specifically, the thermal devices of examples 21-24 were tested. The metallized storage bag was opened to initiate the reaction. The test was carried out by attaching the wired thermocouple to a data collection device on one side of the thermal device. The temperature was recorded as a function of time (at intervals of 5 seconds) to give the thermal curves shown in figure 7. Note that the thermal response curves for the samples of examples 21-24 are lower in temperature but more prolonged than those for the samples of examples 18 and 19 (figure 6). Therefore, the amount of salt in the liquid maintained by the moisture containment layer can be used to control the thermal response curve.

EXAMPLE 26 The capacity to breathe of the bag was measured for examples 6-9 and 11-14 to verify that the large difference in the thermal response curves (Figures 4 and 5) was not due to the variability in the breathing capacity of the bag. The bag for these examples was a laminate of microporous film bonded with nylon yarn obtained from Mitsubishi International Corp., and labeled TSF type EDFH 5035. The water vapor transmission rate of laminate was measured at 455 + 14 grams per square meter for 24 hours (10 samples) using the cup method (ASTM standard E-96E-80). This same method was used to measure the water vapor transmission rate for the bags of Examples 6-9 and 11-14 after the exothermic reaction was completed. The results are shown in table 13.

Table 13: Ability to Breathe (Water Vapor Transmission Rate) for Bags of Examples 6-9 and 11-14 The data shown in Table 3 verify that the bags used for the thermal devices of Examples 6-9 and 11-14 were consistent in the ability to breathe. Therefore the large differences in the thermal response curves for these thermal devices can be attributed to the liquid applied to the layer containing moisture (water or 10% sodium chloride in water) and / or the composition of the exothermic coating (for example, of salt) .

EXAMPLE 27 The ability to control the delivery of moisture by a moisture containing layer for use in the thermal device of the present invention was demonstrated. Four different samples were tested. Samples A and B were formed from an air-laid fabric that contained 75% by weight of wood pulp fluff (Weyerhaeuser NB416), 15% by super absnt weight, and 10% by weight of bicomponent fibers "T255" PE / PP (KoSa). The fabric placed by air had a basis weight of 225 grams per square meter and a density of 0.12 grams per cubic centimeter. Samples C and D were formed from an air-laid fabric that contained 90% by weight of wood pulp fluff (Weyerhaeuser NF405) and 10% by weight of bicomponent fibers "T255" PE / PP (KaSo). The fabric placed by air obtained a basis weight of 175 grams per square meter and a density of 0.08 grams per cubic centimeter. The super absnt was obtained from Degussa AG under the name "SXM 9543".

Each substrate placed by air was cut to a size of 3.5 inches by 4.0 inches and sprayed on each side with an aqueous solution so that the wet weight was about 3.7 to 4.0 times higher than the dry weight. For samples A and C, the aqueous solution contained only distilled water. For samples B and D, the aqueous solution contained 10% by weight of sodium chloride in distilled water. The wet substrates were placed on scales located within the environmental chamber. The humidity and temperature inside the chamber were then recorded as a function of time. In addition, the weight of each wet substrate was also recorded to obtain the "percentage of moisture loss" as a function of time. The "moisture loss percentage" was calculated by subtracting the wet weight measured from the original wet weight, dividing this value by the original wet weight, and then multiplying by 100. The resulting evaporation curves are shown in Figure 8. Note that sample B (SAP / salt water) delivered more moisture as a function of time (eg higher evaporation rate) compared to sample A (SAP / water). Also, sample D (without SAP / salt water) had a moisture delivery rate slightly higher than that of sample B, but much less than sample C (no SAP / water).

EXAMPLE 28 The ability to form a thermal device was demonstrated. Initially, a 7-inch-wide roll of a dual-layer bonded carded fabric was provided. One side of the fabric contained 0.5 ounces per square yard of a 100% FiberVisions ESC 215 bi-component fiber (PE sheath / PP core) of 1.5 denier with 0.55% finished HR6. The other side of the fabric contained 1.75 ounces per square yard of a 40% blend of a T-295 Polyester fiber Invista of 15 denier with 0.50% finished Ll and 60% of a bicomponent fiber FiberVisions ESC (PE sheath / core PP) of 28 denier with 0.55% finished HR6. So, the total basis weight of the dual layer bonded carded fabric was 2.25 ounces per square yard.

An aqueous coating formulation was prepared as follows. In a 1 gallon metal bucket, 34.5 grams of METOLOSE SM-100 (Shin-Etsu Chemical Co., Ltd.) and 87.0 grams of sodium chloride (Mallinckrodt) were added to 1172.1 grams of distilled water which were stirred and heated at 68 degrees Celsius. The mixture was stirred and allowed to cool as the following additional ingredients were added sequentially: 139.1 grams of an ethylene-vinyl acetate emulsion DUR-O-SET® Elite PE 25-220A (Celanese Emulsions), 330.8 grams of calcium carbonate solution sample # 05.2435503 XP-5200-6 (Omya), 72.0 grams of Nuchar SA-400 activated carbon (MeadWestvaco), and 1181.0 grams of iron powder A-131 (North American Hógan s). After about 30 minutes of stirring the formulation with all the ingredients, the temperature was reduced with an ice bath at about 15 ° C. A noticeable increase in viscosity occurred when the temperature was reduced. Finally, the temperature of the formulation was increased with a hot water bath at 22 ° C before the coating of the carded and bound fabric. The calculated concentration of each component of the aqueous formulation is stated below in Table 14.

Table 14: Components of the Aqueous Formulation The aqueous formulation was applied to the bicomponent / polyester fiber side of said dual layer bonded and carded fabric in a pilot line process using a knife coater. The separation between the blade and the steel roller that carried the fabric was set to 900 microns. The line speed was 0.25 meters per minute. The pilot line coater contained a 4-foot dryer set at 145 ° C which was used to partially dry the coated fabric. The partially dried coated fabric was cut into 17 inch pieces and placed in a laboratory oven at 110 ° C for about 20 minutes to complete the drying step. The concentration of the components of the exothermic composition was calculated from the coated and dried cloth pieces (53.8 ± 2.7 grams), the untreated piece of cloth (4.3 grams), and the composition of the aqueous formulation. The results are set down in table 15 below.

Table 15: Components of the Exothermic Composition A five-layer structure of (1.6 inches by 8 inches) was then designed to activate the exothermic reaction. Specifically, the five-layer structure included one of the coated fabric pieces placed on one side of the moisture containing layer, and another piece of coated fabric placed on the other side of the moisture containing layer. The uncoated side of the fabric pieces faces the moisture containment layer. The moisture containment layer was formed of 75% by weight of wood pulp fluff, 15% by super absorbent weight and 10% by weight of KoSa T255 bicomponent fiber. The moisture containment layer had a basis weight of 225 grams per square meter and a density of 0.12 grams per cubic centimeter. The pulp of wood pulp was obtained from Weyerhaeuser under the name "NB416". The super absorbent was obtained from Degussa AG under the name "SXM 9543".

A "separation layer" was used to separate the moisture containing layer from the coated layer on each side. The separation layer was a film / fabric laminate with small perforated holes to allow steam and gas to pass while preventing the passage of liquid. This was obtained from Tredegar Film Products with the label FM-425 lot number SHBT040060.

Before forming the multi-layer structure, the moisture containment layer (2.0 grams) was wet on each side by spraying 5.8 grams of an aqueous salt solution, an amount that increased the layer's mass by a factor of 3.9. . The salt solution contained 10.0% by weight of sodium chloride in distilled water. Then the separation layer was placed around this with the fabric side of the separation layer in contact with the wet moisture containment layer. A coated layer was then placed on each side on the uncoated side in contact with the film side of the separation layer. The total weight of the two layers was 13.1 grams (9.1 grams of iron). The five-layer structure was then placed inside a bag (3 inches by 9 inches) that was sealed with a heat sealer. The bag was made of a laminate of microporous film bonded with nylon yarn (described in Example 1) which had a layer of short weave fabric heat sealed to the side bonded with nylon yarn. The short woven fabric was produced from 20% wood pulp fluff (50% North softwood kraft fibers / 50% softwood kraft bleached Alabama pine), 58% polyester fiber 1.5 denier (Invista type 103), and 22% joined with polypropylene yarn (Kimberly-Clark Corporation).

The bag was made by folding a 6-inch by 9-inch piece of the materials described above in half to produce the size of 3 inches by 9 inches. A flat wire was measured approximately 21.59 centimeters in length, 2.4 millimeters in width and 0.24 millimeters in thickness was then placed in and against the bend. The wire was obtained from Noranda Aluminum, Inc., with the designation of Alloy 8176 / EEE. A bag of approximately 9.525 millimeters wide and 22.86 centimeters long was formed around the wire by heat sealing the top of the bag to the bottom. A second flat wire with the same characteristics as the first wire was then placed on the other edge of the bag. A second bag of approximately 9.525 millimeters wide and 22.86 centimeters long was formed around the second wire by heat sealing the upper part to the bottom of the bag along the outer edge and 9.525 millimeters from the outer edge.

The resulting thermal device was heat sealed in a metallized storage bag for about 67 hours before activating the reaction.

EXAMPLE 29 A thermal device was formed as described in example 28. The moisture containment layer (2.1 grams) contained 5.8 grams of an aqueous salt solution, an amount that increased the mass of the layer by a factor of 3. 8. The salt solution contained 10.0% by weight of sodium chloride in distilled water. The total weight of the two coated layers was 14.4 grams (10.0 grams of iron). The resulting thermal device was heat sealed in a metallized storage bag for about 67 hours before activating the reaction.

EXAMPLE 30 A thermal device was formed as described in example 28. The moisture containing layer (2.2 grams) contained 5.8 grams of an aqueous salt solution, an amount that increased the mass of the layer by a factor of 3. 7. The salt solution contained 10.0% by weight of sodium chloride in distilled water. The total weight of the two coated layers was 12.1 grams (8.4 grams of iron). The resulting thermal device was heat sealed in a metallized storage bag for one day before activating the reaction.

EXAMPLE 31 A thermal device was formed as described in example 28. The moisture containment layer (2.2 grams) contained 5.9 grams of an aqueous salt solution, an amount that increased the mass of the layer by a factor of 3. 7. The salt solution contained 10.0% by weight of sodium chloride in distilled water. The total weight of the two coated layers was 11.6 grams (8.1 grams of iron). The resulting thermal device was heat sealed in the metallized storage bag for a day before activating the reaction.

EXAMPLE 32 The ability to achieve a controlled heating profile using a thermal device of the present invention was demonstrated. Specifically, the thermal devices of examples 28-31 were tested. The metallized storage bag was opened to initiate the reaction. The test was carried out by attaching a thermocouple wire to a data collection device on one side of the thermal device. The temperature was recorded as a function of time (at intervals of 5 seconds) to give the thermal curves shown in Figure 9.

As shown in Figure 9, the thermal response curves for the samples of Examples 28-31 showed a rapid heating rate (temperature of at least 38 ° C within about 10 minutes) and a temperature profile elevated for an extended period of time.

Although the invention has been described in detail with respect to the specific embodiments thereof, it will be appreciated by those skilled in the art, upon achieving an understanding of the foregoing, that alterations, variations and equivalents of these embodiments can be easily conceived. Therefore, the scope of the present invention should be evaluated as that of the appended claims and any equivalents thereof.

Claims (20)

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

1. A chemically activated thermal device comprising an exothermic composition and a conformable segment that is movably constrained within the thermal device, wherein the segment that can be formed is malleable and has an aspect ratio of from about 20 to about 400.

2. The thermal device as claimed in clause 1, characterized in that the segment that can be formed contains a metal or an alloy thereof.

3. The thermal device as claimed in clause 2, characterized in that the metal is aluminum.

4. The thermal device as claimed in clause 1, characterized in that the aspect ratio of the conformable segment is from about 40 to about 200.

5. The thermal device as claimed in clause 1, characterized in that the conformable segment has a length dimension of from about 5 to about 100 centimeters.

6. The thermal device as claimed in clause 1, characterized in that the conformable segment has a width dimension of from about 0.1 to about 20 millimeters.

7. The thermal device as claimed in clause 1, characterized in that the thermal device comprises segments that can be formed essentially independent and multiple.

8. The thermal device as claimed in clause 7, characterized in that the thermal device comprises from 2 to 100 segments that can be shaped.

9. The thermal device as claimed in clause 1, characterized in that the length dimension of the segment that can be formed is essentially parallel to the length dimension of the thermal device.

10. The thermal device as claimed in clause 1, characterized in that the segment that can be formed is placed inside a bag.

11. The thermal device as claimed in clause 10, characterized in that the ratio of the width of the bag to the width of the segment that can be formed is from about 1.0 to about 10.0.

12. The thermal device as claimed in clause 10, characterized in that the ratio of the width of the bag to the width of the segment that can be formed is from about 2.0 to about 5.0.

13. The thermal device as claimed in clause 10, characterized in that the bag is located on one side of the periphery of the thermal device.

14. The thermal device as claimed in clause 10, characterized in that it also comprises an outer cover that is joined together to form the bag.

15. The thermal device as claimed in clause 14, characterized in that the outer cover comprises a material capable of breathing.

16. The thermal device as claimed in clause 1, characterized in that the exothermic composition comprises a metal that can be oxidized which undergoes an exothermic reaction with exposure to oxygen and moisture.

17. The thermal device as claimed in clause 16, characterized in that the exothermic composition further comprises a carbon component, a binder and an electrolytic salt.

18. The thermal device as claimed in clause 1, characterized in that the exothermic composition is coated on a thermal substrate.

19. A package comprising the thermal device of clause 1, characterized in that the thermal device is sealed inside a cover that inhibits the passage of oxygen, moisture or both to the exothermic composition.

20. A method for providing heat to a part of the body, the method comprises placing the thermal device as claimed in clause 1 adjacent to the body part and forming the device to the shape of the body part. SUMMARY A chemically activated thermal device that generates heat with activation is provided. The thermal device typically contains a metal that can be oxidized which is capable of undergoing an exothermic reaction in the presence of moisture and air to generate heat. Although such metals, as well as other components of the composition (e.g. carbon) are relatively inflexible and rigid, the present inventors have nevertheless discovered that one or more conformable segments can be employed to impart flexibility and formability to the thermal device. The conformable segments are malleable so that they yield under the shear stress and acquire the shape of a surface (for example a part of the body) without breaking. The segments that can be shaped are similarly rigid or hard enough to retain essentially the desired shape during use.