Method of making heat cells comprising exothermic compositions having absorbent gelling material

Abstract

The present invention is directed to a method of making heat cells that are suitable for incorporation into disposable heating wraps. The heat cells comprise an exothermic composition comprising an absorbent gelling material, wherein the absorbent gelling material provides for improved heat application in the relief of temporary or chronic body aches and pains.

1 . A method of making a heat cell comprising a particulate exothermic composition, wherein the method comprises the steps of: (a) pre-wetting carbon by mixing with water (b) combining the pre-wetted carbon with an absorbent gelling agent and mixing the pre-wetted carbon with the absorbent gelling agent to form a mixture of pre-wetted carbon and absorbent gelling agent, (c) combining the pre-wetted carbon absorbent-gelling mix with iron powder to form a particulate premix. 
   
   
       2 . The method of  claim 1  wherein the particulate premix composition comprises: (a) from about 10% to about 90% by weight of iron powder; (b) from about 1% to about 25% by weight of a carbon selected from the group consisting of activated carbon, non-activated carbon, and mixtures thereof; (c) from about 1% to about 25% by weight of an absorbent gelling material; and (d) from about 1% to about 10% by weight of water. 
   
   
       3 . The method of  claim 2  wherein the particulate pre-mix composition comprises a median particle size ratio of absorbent gelling material to iron powder of from about 10:1 to about 1:10. 
   
   
       4 . The method of  claim 3  wherein the iron powder has a median particle size of from about 50 μm to about 300 μm. 
   
   
       5 . The method of  claim 4 , wherein the iron powder is selected from the group consisting of cast iron powder, reduced iron powder, electrolytic iron powder, scrap iron powder, pig iron, sponge iron, wrought iron, steel, iron alloy, and mixtures thereof. 
   
   
       6 . The method of  claim 5  wherein the iron powder is sponge iron. 
   
   
       7 . The method of  claim 2  wherein the particulate pre-mix composition comprises from about 1% to about 10% by weight of the activated carbon, non-activated carbon, and mixtures thereof. 
   
   
       8 . The method of  claim 7  wherein the activated carbon is prepared from materials selected from the group consisting of coconut shell, wood, charcoal, coal, bone coal, animal products, natural gas, fats, oils, resins, and mixtures thereof. 
   
   
       9 . The method of  claim 2  wherein the absorbent gelling material is a hydrogel-forming polymeric material having a median particle size of from about 300 μm to about 800 μm. 
   
   
       10 . The method of  claim 9  wherein the hydrogel-forming polymeric material is selected from the group consisting of hydrolyzed acrylonitrile grafted starch, acrylic acid grafted starch, polyacrylate, maleic anhydride-based copolymer, and mixtures thereof. 
   
   
       11 . The method of  claim 1 , the method of  claim 1  further comprising the step of combining the particulate premix with a brine solution, wherein the brine solution comprises: (a) from about 0.5% to about 20% by weight of a metal salt; (b) from about 1% to about 90% by weight of water; and (c) optionally from about 0.01% to about 10% by weight of a hydrogen gas inhibitor. 
   
   
       12 . The method of  claim 11  wherein the metal salt is selected from the group consisting of alkali metal salts, alkaline earth metal salts, transition metal salts, and mixtures thereof. 
   
   
       13 . The method of  claim 12  wherein the metal salt is selected from the group consisting of sodium chloride, cupric chloride, and mixtures thereof. 
   
   
       14 . The method of  claim 13  wherein the hydrogen gas inhibitor is selected from the group consisting of sodium thiosulfate, sodium sulfite, sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, sodium carbonate, calcium hydroxide, calcium carbonate, sodium propionate, and mixtures thereof. 
   
   
       15 . The method of  claim 14  wherein the hydrogen gas inhibitor is sodium thiosulfate. 
   
   
       16 . The method of  claim 1  wherein the heat cell is combined in a pocket, formed in a unified structure comprising at least two opposed surfaces, wherein at least one surface is oxygen permeable. 
   
   
       17 . The method of  claim 16  wherein the heat cell is in a shape selected from the group consisting of disk, triangle, pyramid, cone, sphere, square, cube, rectangle, rectangular parallelepiped, cylinder, ellipsoid, and combinations thereof. 
   
   
       18 . The method of  claim 17  wherein the heat cell is incorporated into disposable heating articles selected from the group consisting of back wraps, knee wraps, neck wraps, menstrual wraps, joint wraps, and neck-to-arm wraps. 
   
   
       19 . A method of making a small heat cell, the method comprises the steps of: (a) pre-wetting carbon by mixing with water (b) combining the pre-wetted carbon with an absorbent gelling agent and mixing the pre-wetted carbon with the absorbent gelling agent to form a mixture of pre-wetted carbon and absorbent gelling agent, (c) combining the pre-wetted carbon absorbent-gelling mix with iron powder to form a particulate premix, (d) depositing about 0.4 to about 2.5 grams of the premix in a pocket in a film substrate to form a cell and wherein the ratio of the fill volume to cell volume is about 0.7 to about 1.0. 
   
   
       20 . The method of  claim 19  wherein the particulate premix composition comprises: (a) from about 10% to about 90% by weight of iron powder; (b) from about 1% to about 25% by weight of a carbon selected from the group consisting of activated carbon, non-activated carbon, and mixtures thereof; (c) from about 1% to about 25% by weight of an absorbent gelling material; and (d) from about 1% to about 10% by weight of water. 
   
   
       21 . The method of  claim 20  wherein the particulate pre-mix composition comprises a median particle size ratio of absorbent gelling material to iron powder of from about 10:1 to about 1:10. 
   
   
       22 . The method of  claim 21  wherein the iron powder has a median particle size of from about 50 μm to about 300 μm. 
   
   
       23 . The method of  claim 20  wherein the particulate pre-mix composition comprises from about 1% to about 10% by weight of the activated carbon, non-activated carbon, and mixtures thereof. 
   
   
       24 . The method of  claim 23  wherein the activated carbon is prepared from materials selected from the group consisting of coconut shell, wood, charcoal, coal, bone coal, animal products, natural gas, fats, oils, resins, and mixtures thereof. 
   
   
       25 . The method of  claim 20  wherein the absorbent gelling material is a hydrogel-forming polymeric material having a median particle size of from about 300 μm to about 800 μm. 
   
   
       26 . The method of  claim 19 , the method further comprising the step of combining the particulate premix with a brine solution, wherein the brine solution comprises: (a) from about 0.5% to about 20% by weight of a metal salt; (b) from about 1% to about 90% by weight of water; and (c) optionally from about 0.01% to about 10% by weight of a hydrogen gas inhibitor 
   
   
       27 . The method of  claim 26  wherein the metal salt is selected from the group consisting of alkali metal salts, alkaline earth metal salts, transition metal salts, and mixtures thereof. 
   
   
       28 . The method of  claim 26  wherein the hydrogen gas inhibitor is selected from the group consisting of sodium thiosulfate, sodium sulfite, sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, sodium carbonate, calcium hydroxide, calcium carbonate, sodium propionate, and mixtures thereof. 
   
   
       29 . The method of  claim 19  wherein the heat cell is combined in a pocket, formed in a unified structure comprising at least two opposed surfaces, wherein at least one surface is oxygen permeable. 
   
   
       30 . A method of making a heat producing disposable heating article comprising separately placing a plurality of the small heats cells of  claim 19  in plurality of small pockets in a substrate sheet.