(1) Field of the Invention
This invention relates to chemical heaters.
(2) Description of the Prior Art
Prior to filing this application, a search was made in the public search files of the U.S. Patent and Trademark Office. That search developed the following references:
Reed eT aL: U.S. Pat. No. 3,233,604 PA1 Hollinshead: U.S. Pat. No. 3,585,982 PA1 Donnelly: U.S. Pat. No. 3,903,011 PA1 Krupa: U.S. Pat. No. 3,980,070 PA1 Donnelly: U.S. Pat. No. 4,067,313 PA1 Yoshida eT aL: U.S. Pat. No. 4,093,424 PA1 Kaiho eT aL: U.S. Pat. No. 4,199,548 PA1 Fujiwara: U.S. Pat. No. 4,205,957 PA1 Marshall eT aL: U.S. Pat. No. 4,265,216 PA1 Abe: U.S. Pat. No. 4,366,804
All of the above references disclose selected materials that produce heat by exothermic reaction when mixed. Yoshida eT aL and Kaiho eT aL disclose exothermic reactants or metal sulfides, poly sulfides, or hydrosulfides mixed with a catalyst carried by carbonaceous materials that react when exposed to air as an oxygen source. These two references also use a filler, such as waste of foamed synthetic resins, silica powder, wood dust or material, or synthetic fibers (e.g. polyester fibers, polystyrene and polyurethane foams, and cotton linters), that act as a heat buffer and heat sink. The filler disclosed does not take part in the reaction.
Fujiwara, Abe, Reed eT aL, and Krupa, disclose iron filings, or other metal particles, which are combined with an alkali metal salt, such as potassium chlorate, magnesium chloride, potassium nitrates, magnesium nitrates, among others, in aqueous solution, in some disclosures, in the presence of a catalyst, such as noble metals carried by carbonaceous materials. Abe also discloses a water carrying member to soak up water that is then fed to the dry reactants as needed. The water carrying member may include rubber, synthetic resin, cellulose, or other highly absorbent, nonreactive material.
Hollinshead discloses encapsulation of a reactant in a solution, with the capsules broken to mix exothermic reactants. The reactants disclosed by Hollinshead include, among others, peroxide, perborate and persulfate salts, reacted with magnesium, zinc, iron, aluminum sulfites, and barbituric acids.
Donnelly, in '011 and '313, discloses adding water to an anhydrous mixture of (a) calcium chloride, or other "primer," such as cerous chloride, cesium hydroxide, sodium carbonate, among other, and (B) an organic oxide or salt, such as calcium oxide, aluminum chloride, calcium nitrate.
Marshall eT aL disclose mixing magnesium chloride and ethylene glycol.
A few of the above cited references disclose various rupturable containers of one reactant or water or aqueous solution within a larger, impervious container also containing reactants. Marshall eT aL also disclose tear strips between separate compartments, whereas Hollinshead shows encapsulation to separate reactants. Other references simply provide for additions of water directly by the user.
USPTO Backgrounds
USPTO Backgrounds