Reusable warmers of the type employing a super-cooled solution and an activator

Abstract

The present invention provides reusable warmers of the supersaturated solution type that are substantially free of saddlebagging. The warmers also exhibit a more sustained period of time during which the heat pack remains within a therapeutically useful temperature range. The reusable warmers of the present invention also maintain a substantial degree of flexibility during their useful heat cycle. The reusable warmers comprise a flexible container, and located within said container, a supercooled salt solution, an activator for initiating crystallization of said supercooled salt solution, and a gelling agent, said gelling agent being present in sufficient quantity to convert said salt solution to a gel.

What is claimed is: 
     
       1. A reusable warmer comprising a flexible container, and located within said container, a .[.supercooled.]. .Iadd.super-cooled salt .Iaddend.solution of sodium acetate, an activator for initiating crystallization of said .[.supercooled.]. .Iadd.super-cooled salt solution of sodium acetate, and a gelling agent, said gelling agent being present in sufficient quantity to convert said salt solution to a gel which remains deformable after crystallization of said salt solution. 
     
     
       2. The reusable warmer of claim 1 wherein the gelling agent is a non-ionic, water-soluble hydroxyethylcellulose polymer. 
     
     
       3. The reusable warmer of claim 1 wherein the gelling agent is selected from the group consisting of cellulose ethers. 
     
     
       4. The reusable warmer of claim 3 wherein the gelling agent is selected from the group consisting of methylcellulose, hydroxypropyl cellulose, methylhydroxypropyl cellulose, polypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, .[.and.]. hydroxymethyl cellulose, carboxymethylhydroxyethyl cellulose, hydroxypropylmethyl cellulose, hydroxyethyl propylcellulose, and hydroxybutyl methylcellulose. 
     
     
       5. The reusable warmer of claim 1 wherein the gelling agent is selected from the group consisting of starch graft copolymers. 
     
     
       6. The reusable warmer of claim 1 wherein the gelling agent is selected from the group consisting of natural and synthetic gums. 
     
     
       7. The reusable warmer of claim 6 wherein the gelling agent is selected from the group consisting of Irish moss, gum tragacanth, viscarin GMC, kappa- and iota carrageenan, sodium alginate, guar, hydroxypropyl guar, carboxymethyl-hydroxypropyl guar, hydroxy ethyl guar, alginates, carrageenan, xanthan gum, gelatin, agarose, gum arabic, carob, tragacanth, locust bean gum, karaya, pectin, agar, gum acacia, tara gum, polysucrose, polyglucose, and zooglan. 
     
     
       8. The reusable warmer of claim 1 wherein the gelling agent is selected from the group consisting of synthetic polymers and copolymers which are hydratable and cross-linkable in solution. 
     
     
       9. The reusable warmer of claim 8 wherein the gelling agent is selected from the group consisting of polyacrylates, polymethylacrylates, polyacrylamides, acrylamide methyl propane sulfonic acid copolymers, polyvinyl alcohols, maleic anhydride-base copolymers, polyvinyl pyrollidone, polyvinyl alcohol, polyacrylic acid, copolymers of acrylic acid and a polyallyl sucrose, polyoxyethylene-polyoxypropylene diol block copolymers.Iadd., .Iaddend.carboxypolymethylene, and polyacrylamide. 
     
     
       10. The reusable warmer of claim 1 wherein the gelling agent is selected from the group consisting of poly(ethylene oxide) polymers. 
     
     
       11. The reusable warmer of claim 1, wherein said sodium acetate is present in an amount of from about 40% to about 50% by weight. 
     
     
       12. The reusable warmer of claim 1, wherein said sodium acetate is present in an amount of about 40% by weight. 
     
     
       13. The reusable warmer of claim 1, wherein said sodium acetate is present in an amount of about 50% by weight. .Iadd. 
     
     
       14.  A heat pack comprising a flexible container, a super-cooled salt solution comprising a salt and a solvent located within said flexible container, an activator for initiating crystallization of said salt solution, and a gelling agent in sufficient quantity to convert said salt solution to a gel such that said gel remains deformable after crystallization of said salt solution. .Iaddend..Iadd.15. The heat pack of claim 14, wherein said gelling agent is a nonionic, water-soluble hydroxyethylcellulose polymer. .Iaddend..Iadd.16. The heat pack of claim 14, wherein said gelling agent is a cellulose ether. .Iaddend..Iadd.17. The heat pack of claim 16, wherein said gelling agent is selected from the group consisting of methylcellulose, hydroxypropyl cellulose, methylhydroxypropyl cellulose, polypropyl cellulose, carboxymethyl cellulose, hydroxyethyl cellulose, hydroxymethyl cellulose, carboxymethylhydroxyethyl cellulose, hydroxypropylmethyl cellulose, hydroxyethyl propylcellulose, and hydroxybutyl methylcellulose. .Iaddend..Iadd.18. The heat pack of claim 14, wherein said gelling agent is a starch graft copolymer. .Iaddend..Iadd.19. The heat pack of claim 14, wherein said gelling agent is a natural or synthetic gum. .Iadd.20. The heat pack of claim 19, wherein said gelling agent is selected from the group consisting of Irish moss, gum tragacanth, viscarin GMC, kappa- and iota-carrageenan, sodium alginate, guar, hydroxypropyl guar, carboxymethyl-hydroxypropyl guar, hydroxy ethyl guar, alginates, carrageenan, xanthan gum, gelatin, agarose, gum arabic, carob, tragacanth, locust bean gum, karaya, pectin, agar, gum acacia, tara gum, polysuccrose, polyglucose, and zooglan. .Iaddend..Iadd.21. The heat pack of claim 14, wherein said gelling agent is a synthetic polymer or copolymer which is hydratable and cross-linkable in solution. .Iaddend..Iadd.22. The heat pack of claim 21, wherein said gelling agent is selected from the group consisting of polyacrylates, polymethyacrylates, polyacrylamides, acrylamide methyl propane sulfonic acid copolymers, polyvinyl alcohols, maleic anhydride-based copolymers, polyvinylpyrollidone, polyvinyl alcohol, polyacrylic acid, copolymers of acrylic acid and a polyallyl sucrose, polyoxyethylene-polyoxypropylene diol block copolymers, carboxypolymethylene, and polyacrylamide. .Iaddend..Iadd.23. The heat pack of claim 14, wherein said gelling agent is a poly(ethylene oxide) polymer. .Iaddend..Iadd.24. The heat pack of claim 14, wherein said salt is sodium acetate. .Iaddend..Iadd.25. The heat pack of claim 24, wherein said sodium acetate is present in said salt solution in an amount of from about 40% to 
     
     
        about 50% by weight. .Iaddend..Iadd.26.  The heat pack of claim 24, wherein said activator is located within said flexible container. 
     
     
        .Iaddend..Iadd.27.  The heat pack of claim 25, wherein said sodium acetate is present in said salt solution in an amount of about 40% by weight. .Iaddend..Iadd.28. The heat pack of claim 25, wherein said sodium acetate is present in said salt solution in an amount of about 50% by weight. 
     
     
        .Iaddend..Iadd.29.  The heat pack of claim 25, wherein said activator is 
     
     
        located within said flexible container. .Iaddend..Iadd.30.  The heat pack of claim 14, wherein said activator is located within said flexible container. .Iaddend.