Patent Application
20080097356
For a more complete understanding of the invention, reference is hereby made to the drawings, in which:
As shown in
Also enclosed in package 11 is an outer pouch 17 made of a fluid impervious material such as a plastic. Pouch 17 contains the heat generating materials 19 that exotherm when contacted by an actuating agent as described below. Heat generating materials 19 are preferably in crystal or granular form so that they can be spread throughout the inside of pouch 17, thus, when activated, providing exotherm heat over the whole wipes 13.
Preferred is an outer pouch 17 made from Aclar®, which is a polychlorotrifluoroethylene (PCTFE) material manufactured and sold by Honeywell International Inc. Aclar film is crystal clear, biochemically inert, chemical-resistant, nonflammable, and plasticizer- and stabilizer-free. Aclar laminates provide a wide range of gauges and thus barrier levels to allow flexibility in selecting the optimum barrier level for the chemical system chosen. Other similar pouch materials may be used as well. All that is required is that the material have a functional moisture and vapor barrier for the other components of the invention.
As seen in
Preferred is an inner pouch 21 made from a heat stamp foil such as.
Pouch 21 has a frangible seal 25 that is preferably broken at the appropriate time by flexing or bending the package 11 to cause the activating agent 23 to mix with the heat generating material 19 and exotherm at the many locations inside outer pouch 17.
In order to have an uniform and even production of heat from the exotherms, it is preferred that the inside of inner pouch 21 be at atmospheric pressure or 14.7 psi, and the inside of the outer pouch 17 be under vacuum. Preferred pressures in outside pouch 17 are from about 8 psi to about 13 psi, with 10 or 11 psi being preferred. It is necessary to have a pressure differential between the inside of both pouches to be sufficient to pull the activating agent 23 to the entire area where the heat generating material 19 has been placed. Too little or too great a pressure differential is not desired, for design and reliability reasons.
There are a number of combinations of heat generating materials and activating agents that are suitable for use in the present invention. The selection of specific components is to be based upon cost, compatibility, ease of control of the exotherm, and other factors.
The preferred activating material of this invention is water. This is plentiful and safe, and reacts with a number of materials to produce an exothermic reaction.
The preferred heat generating material is a crystal formed from several components that, when free from moisture, are stable for up to three to five years or more, and which react when moisture is present to generate heat. The preferred crystal is made from a crystalline mixture of calcium oxide and citric acid. The weight of the heat generating material to the volume of actuation agent ranges from about 1:2 to about 1:1, and preferably about 3:4. In the most preferred mixture of the heat generating material is a mixture of calcium oxide and citric acid with the further addition of a zeolite powder. Preferred is a ratio of calcium oxide to citric acid to powdered zeolite is from about 14 to 20 for calcium oxide, from about 1 to 2 for citric acid, and from about 7 to 10 for powdered zeolite. Most preferred is a ratio of calcium oxide to citric acid to powdered zeolite is 17:1.5:8.5 and the ratio of the solids to the volume of water is about 3:4.
More than 150 zeolite types have been synthesized and 48 naturally occurring zeolites are known. They are basically hydrated alumino-silicate minerals with an “open” structure that can accommodate a wide variety of positive ions, such as Na+, K+, Ca2+, Mg2+ and others. These positive ions are rather loosely held and can readily be exchanged for others in a contact solution. Some of the more common mineral zeolites are: analcime, chabazite, heulandite, natrolite, phillipsite, and stilbite. An example mineral formula is: Na2Al2Si3O10.16H2O.
The heat generation material most preferred, using the above components includes a calcined calcium oxide. This material is available as a small article size, with a diameter less than about 0.2 mm, and as a particle of somewhere between 0.2 and 0.8 mm. Larger particles are ground and smaller ones sieved, and the calcium oxide is then calcined. It has been found to be effective to calcine for at least 60 to 120 minutes, and preferably about 90 minutes, at temperatures above 500° C., and most preferably at about 550° C. for that period of time. The calcined calcium oxide is, of course, desiccated to prevent any contamination by moisture. Laboratory grade citric acid and powdered zeolite are mixed with the calcium oxide in moisture free conditions, in an appropriate reaction ratio to provide the exothermic reaction upon contact by the activating agent water.
The heat generating mixture 19 is spread throughout the inside of outer pouch 17 and covers parts of inner pouch 21, obviously separated from the activating agent 23 inside pouch 21. The vacuum is then pulled inside pouch 17 to assist in dispersing the activating agent. This combination of pouches is placed with the desired quantity of personal hygiene wipes 15 inside package 11 and sealed for distribution and sale.
In a series of tests of the preferred embodiment as described above, 100% of the activations by bending the packages resulted in warm personal hygiene wipes. Then a similar set of packages were prepared, with the only change being no vacuum inside the outer pouch, only 30% of the wipes achieved the desired temperature,
While particular embodiments of the present invention have been illustrated and described, it is not intended to limit the invention to any specific embodiment. The description of the invention is not intended to limit the invention.
