Patent Application
20180071971
The present invention relates to a thermoformable article and its components, and more specifically to a thermoformable article having a heater which utilizes water and a reactant to generate the heat required to form the article.
Thermoformable articles typically become moldable or formable when a heat source is applied to them. In some known articles, a heater or the like may be included with or coupled to the article. For example, U.S. Pat. Pub. Nos. 2015/0257917 and 2015/0257918 to Rechargeable Battery Corporation, a thermoformable article in the form of a splint is disclosed wherein the article includes a heater which couples to the exterior of the article. The heaters used for thermoformable articles are typically oxygen activated heaters like those described in the printed publications to Rechargeable Battery Corporation.
Heat sources using other chemical reactions can be used to generate heat which may be used to heat thermoformable articles to a formable temperature. When, for example, an inorganic salt having higher hydration energy than lattice energy is hydrated, energy in the form of heat is released. The available heat of hydration in such instances will depend on the choice of salt and the final degree of hydration of the salt. As such, a careful selection of the salt and proper ratio of the salt to water are key considerations when wanting to generate enough heat to make the thermoformable material moldable, while at the same time avoiding excessive temperatures which may burn users of the thermoformable material.
An additional problem with using a heat source utilizing salt and water to generate heat is that the combined salt and water may create an undesirable wet, sticky substance which can irritate a user and be uncomfortable. Washing the resulting substance away from the thermoformable material may be difficult once fit to a user or if a wicking or fabric layer is used in conjunction with the salt and/or water.
Depending on the salt used in the heating device and location parameters like the relative humidity, the salt may also continue to absorb water out of the air. Continued absorption of water may cause the salt to continue to generate heat while become heavier as the water is absorbed. Continued heating can lead to higher than desired temperatures or an extended setting time of the thermoformable material.
The present invention is provided to solve these and other issues.
The present invention is directed to a thermoformable article which includes a thermoformable body and a heat source, where a solution of a reactant or heater material, like for example water and an anhydrous salt, are, at the desired time of heating, mixed together in order to generate heat. The hydration energy of the used heater material (such as a salt like anhydrous MgCl2) should be greater than the lattice energy which will cause a burst of energy (released as heat) when the heater material and water are mixed.
In order to avoid premature or undesired heating, the water and the heater material, i.e. salt, should be stored and transported separately, and only introduced to each other at the desired time of heating. A thickening agent could be added to the heater material and/or the water to increase the viscosity. A wax material could be introduced to the heater material and/or water to increase the ability of the system to store energy and heat for longer periods of time.
It is also contemplated that part of the packaging may include in part a liquid impermeable, gas permeable, film such as flashspun high-density polyethylene fibers. Although the use of a separate water pouch may be used, it is also contemplated that water may be applied via other means, such as pouring water on to the thermoformable article. The amount and type of salt, water, thickening agent, and/or wax will determine the heat of the final mixture.
The heating element of the present invention utilizes the enthalpy of solution (heat of hydration) to provide heat. For example, in some cases when an anhydrous salt is mixed with water, energy is released as it goes into solution. The heat given off may be used to heat a thermoformable product. Anhydrous magnesium chloride (MgCl2) is an example of a salt that gets quite hot when it is wetted.
According to one aspect of the invention, a thermoformable article is provided. The thermoformable article includes a thermoformable body constructed using material which is rigid at temperatures below a thermoformable temperature and becomes formable when heated to a temperature at least as high as the thermoformable temperature. Materials may be used which become thermoformable at, for example, 140 degrees Fahrenheit, 160 degrees Fahrenheit, etc. Examples of materials which may be used to create the body include, but are not limited to, polylactic acid (PLA) polymer, cellulose acetate butyrate, polycaprolactone, ethylene vinyl acetate, poly(caprolactone), poly(hydroxybutyrate), polyethylene, polypropylene, polystyrene and combinations thereof.
The thermoformable article further includes a heater material, the heater material being in thermal contact with the body when the heater material is activated. The heat generated by the heater material once the heater material is activated is provided by an enthalpy of solution of the heater material.
In order to activate the heater material, the thermoformable article may include a pouch or packet of water. Regardless of how housed, the water should initially be isolated from the heater material. Once combined, the heater material should have a weight between 5% and 20% of the total combined weight of the heater material the water and any other additives like wax or a thickening agent, for example. A heater material should be selected so that it becomes activated when the water is combined therewith.
The heater material may a salt or mixture of salts having a negative enthalpy of solution, and wherein the salt or mixture of salts is activated through hydration. For example, the heater material may include MgCl2, KCl, KBr, NaCl, LiCl, LiI, CuSO4, FeCl2, MgSO4, CaCl2, CaO and mixtures thereof. The heater material may be a salt or mixture of salts having a negative enthalpy of solution, and wherein the salt or mixture of salts is activated through hydration. The solution resulting from the hydration of the heater material or salt or the mixture of salts preferably has a relative humidity in the range of 40%-70%, and more preferably a relative humidity in the range of 50%-60%. Having a relative humidity within those ranges will prevent the heater material from continuing to absorb water from the environment after being activated by the water provided or added by a user.
In some embodiments of the invention, the heater material may be physically isolated from the body. For example, the thermoformable article may include a barrier film bag or the like, the barrier film bag may be removably attached to a first side of the body and may have a first compartment and a second compartment separated by a frangible seal. The heater material may be housed within the first compartment and water may be housed in the second compartment, and the breaking of the frangible seal causes the heater material and water to mix, activating the heater material. In order to prevent damage to the heating portion and potential injury to a user, the first compartment may include a vent hole to allow steam and air pressure generated from the combining of the heater material and the water to escape the barrier film bag so the bag does not explode.
In other embodiments where the heater material is physically isolated from the thermoformable body, rather than use a bag having one or multiple compartments, the thermoformable article may include a barrier film or the like. When a barrier film rather than a bag is used, the heater material may be deposited on a first side of the barrier film and covered with a removable, peelable flap, while the second side of the barrier film is removably attached to a surface of the thermoformable body. An activating agent like water may then be provided in a separate container with the thermoformable article, or may be supplied by a user from an external source.
In other embodiments of the invention, the heater material may be integrated or included directly with the thermoformable body. In order to hold and accommodate the heater material and prevent the heater material from escaping before and after activation, the body may include one or more cavities formed in a first surface of the body, the plurality of cavities having heater material embedded therein. The thermoformable article may then also include a wicking layer which is removably engaged with the first surface of the body to cover the first surface, the plurality of cavities and the heater material embedded therein.
In some embodiments where the heater material is integrated within a cavity or a plurality of cavities formed in a surface of the thermoformable body, the thermoformable article may include a barrier film bag having a first compartment and a second compartment separated by a frangible seal. The first compartment may house an activator for the heating material, like for example water, while the second compartment houses the body having a cavity or a plurality of cavities with heater material embedded therein and any wicking layer which may or may not be fixed over the cavities and heater material. The activator will mixes with the heater material when the frangible seal is broken, causing the heater material to become activated. A vent may be provided in the second cavity to allow for the escape of steam and air pressure as the heater material is activated and heated.
In other embodiments where the heater material is integrated within a cavity or a plurality of cavities formed in a surface of the body, the thermoformable article may include a barrier film bag having a removable portion and a single main interior pouch for housing the body, the heater material and any wicking layer which may or may not be fixed to the body over the cavity or cavities and heater material. Within the main pouch, a second pouch containing an activator like water may be provided. Removal of the removable portion of the bag will allow access to the thermoformable body and integrated heater material and any wicking layer, as well as the second pouch holding the activator for the heating material. The removable portion may be removed using any method or means known in the art. For example, the barrier film bag may include a notch for tearing away the removable portion.
In yet other embodiments where the thermoformable body includes a cavity or a plurality of cavities having heater material embedded therein, the thermoformable article may include a barrier film bag having a removable portion and a first compartment and a second compartment separated by a permanent heat seal. The first compartment may house an activator for the heater material, like for example water or water in the form of a water soaked pad, while the second compartment houses the body, the heater material and any wicking layer which may or may not be removably engaged with the body to cover the heater material. Removal of the removable portion of the bag will allow access to the thermoformable body and integrated heater material and any wicking layer, as well as the activator for the heating material, for example the water soaked pad or sponge. The removable portion may be removed using any method or means known in the art. For example, the barrier film bag may include a notch for tearing away the removable portion.
It is to be understood that the aspects and objects of the present invention described above may be combinable and that other advantages and aspects of the present invention will become apparent upon reading the following description of the drawings and detailed description of the invention.
While this invention is susceptible of embodiment in many different forms, there is shown in the drawings and will herein be described in detail one or more embodiments with the understanding that the present disclosure is to be considered as an exemplification of the principles of the invention and is not intended to limit the invention to the embodiments illustrated.
The wicking layer may be attached to body 10 in any manner known in the art, including heat bonding to the body or using an adhesive. In either case, it is preferable, though not required, that the wicking layer be removably engaged with the body so that the wicking layer can be removed once heating is completed and the body is formed in order to decrease the weight of the body, and allow a user to wash way or remove any heater material and activator which is trapped in or under the wicking layer. For example, the wicking material may be heat bonded to the body at a temperature, or may be adhered to the body in a manner, that allows the user to “peel” the wicking layer off once the heating is done so the user may wash away the heater material.
Thermoformable body 10 essentially includes everything required to form the body except an activator to cause the activation of heater material 14. In order to activate the heater material, a user may provide an activator, for example water, by introducing any required activator to the wicking layer, allowing it to absorb and/or seep through and activate heater material 14. The activator may be provided by a user, for example, from an external source, or may be included with the thermoformable body.
In this configuration, when activation of the thermoformable article is desired, frangible seal 26 is broken by applying pressure to first compartment 22 for example, allowing activator 28 to mix with the heater material by passing through wicking layer 16. Once activated, the heating material will begin generating heat with any resulting steam or building of air pressure being vented through vent 30 in turn causing the heating of thermoformable body 10. Once the body is heated to its malleable point and becomes formable, a user may remove the body from bag 20 and form the body as desired. Once heating and formation are complete, the user may then remove the wicking layer and rinse the thermoformable body to remove any remaining activator and/or heater material.
As seen in
When activation of the heating material and formation of the body in the embodiment shown in
Removable portion 32′ in the embodiment shown in
Second pouch or container 36′ may likewise take any form known in the art capable of housing and sealing, while permitting selective access to, an activator which may be, for example, water or water with thickeners or wax added thereto. For example, the second pouch may be a barrier bag similar to barrier bag 20′ or may be a vial or container having a removable lid or end.
Similar to the embodiment shown in
In order to access the first and second compartments and activate the heater material and ultimately form body 10, bag 20″ may include a removable portion 32″ which may be substantially similar and removable in the same manners discussed with respect to the embodiment shown in
Rather than use water as an activator, the embodiment shown in
Thus far, each of the embodiments discussed herein have include a thermoformable body which has cavities to allow for the integration of a heater material therewith. While integrating the heater material with the body and providing direct contact between the material and body may provide for the most efficient and best heat transfer, when an activator like water and a heater material like a salt or salt mixture is used, the resulting compound can be difficult to clean up and can result in an uncomfortable user experience.
Therefore, the present invention further contemplates thermoformable articles which have a thermoformable body which is isolated from a heater material and/or activator to allow for easier clean up and removal of an activated and/or spent heater material once the body is fully formed. An exemplary embodiment is shown in
In
In order to activate the heater material, the frangible seal may be broken by applying pressure to the first compartment. Once activated, the barrier bag may be adhered to or placed on a surface of the thermoformable body. Once heating and formation are complete, the barrier bag may be removed from the thermoformable article and discarded. Since the heater material and activator are enclosed and isolated from the thermoformable body, there is no need to wash away and residual heater material and/or activator from the body as the material and activator never come into contact with the body.
As seen in
A flap or seal 244 may be disposed over heater material 214 in order to prevent premature or unwanted activation of the heater material, as well as to hold and prevent the escape of the heater material. Wicking material or a wicking layer may be disposed between flap or seal 244 in order to prevent heater material from being pulled away from barrier film layer 242 when the flap or seal is removed, and to prevent the heater material from spilling or dispersing once the flap or seal is removed and when activator is added to the heater material.
When activation of heater material 214 is desired, flap or seal 244 may be removed and an activator like water added to the heater material. Once heating and formation of body 210 is complete, barrier film 242, along with heater material 214 and any activator and wicking layer can be removed from body 210. Since there is no direct contact between the body and heater material and/or activator, body 210 should be clean and not require additional clean up.
An activator may be provided with thermoformable article 218 or supplied by a user. For example, it should be understood that thermoformable body 210, barrier film layer 214, heater material 214 and flap or seal 244 may replace the combination of body 10, wicking layer 16 and heater material 14 in any of the embodiments shown in
Regardless of the embodiment, the heater material should be a material where the hydration energy is greater than the lattice energy. When such a material is mixed with activator, the result will be a burst of energy, which will be released as heat. The enthalpy of solution (heat of hydration) of the resulting mixing of the heater material and activator is used to provide heat. As has been mentioned throughout, one such combination of heater material and activator which will result in the generation of such heat is salt or a mixture of salts and water, or a solution or mixture of water having other elements added like thickening agents or wax. Anhydrous magnesium chloride (MgCl2) is an example of a salt that gets quite hot when it is wetted.
The amount of heat generated by a salt and water solution, must be enough to heat the thermoformable body to a thermoformable temperature, but should be kept at a level where risk of bums or and uncomfortable user experience can be avoided as much as possible. The following graph shows the heat generated from the enthalpy of solution of MgCl2 at different concentrations, with the temperatures being measure proximate a middle area of a beaker containing a solution of MgCl2 and water.
As can be seen in the graph above, the % of salt in the resulting solution has a progressive correlation with the temperature—as % MgCl2 increases, temperature increases. Therefore, a solution having enough MgCl, concentration to generate enough heat to make the thermoformable body formable must be selected, without providing too much MgCl2 in order to avoid the production of high levels of heat which may burn a user or damage the thermoformable body. It has been found that generally a range of 5%-20% MgCl2 by weight in the mixed solution of MgCl2 and water generates the proper level of heat to make the thermoformable body thermoformable while preventing burns to a user or damage to the thermoformable body.
Although MgCl2 was been disclosed and given as an example, examples of other salts having a negative enthalpy of solution may be used as well. For example, the following table shows the enthalpy of solution for other salts which may be utilized as the heating material:
It is to be understood that additional embodiments of the present invention described herein may be contemplated by one of ordinary skill in the art and that the scope of the present invention is not limited to the embodiments disclosed. While specific embodiments of the present invention have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention, and the scope of protection is only limited by the scope of the accompanying claims.
The present application claims priority to U.S. Provisional Patent Application No. 62/143,889 filed Apr. 7, 2015 the contents of which are expressly incorporated herein by reference.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/US2016/026378 | 4/7/2016 | WO | 00 |
| Number | Date | Country | |
|---|---|---|---|
| 62143889 | Apr 2015 | US |
