Patent Application
20160161149
None.
The present invention generally relates to heaters and articles having heaters embedded therein. More specifically, the present invention relates to substantially dry oxygen activated heaters and thermoformable articles having heaters embedded or engrained therein.
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 For example, in pending but unpublished applications to Rechargeable Battery Corporation, a thermoformable article in the form of a splint is disclosed wherein the article includes a heater which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. While attaching the heater to the exterior of the article provides satisfactory results, particularly for thinner or smaller articles, the heating of the article resulting from the surface heater may not be uniform and may not substantially penetrate the article quickly. This may result in longer heating times, articles which do not uniformly heat for molding, and may also result in higher molding temperatures, which in turn may lead to longer setting times or damage to the article. Additionally, placing the heater on just the outer surface of the article means that only a portion of the heat generated by the heater is transmitted to only a portion of the article. For thicker articles, the heat may not successfully transfer heat throughout the article, causing at least a portion of the article to remain static while the rest is moldable.
The heaters used for thermoformable articles are typically oxygen activated heaters like those described in the pending but unpublished applications to Rechargeable Battery Corporation. In addition to using the oxygen activated heaters for thermoformable objects, they may have numerous other uses, like, for example, heating food and as hand, foot or body warmers. Known oxygen activated heaters are typically manufactured using a wet process with a material which includes zinc, carbon, an optional binder, and water. The heater mix is rolled into sheets and dried in an oven. As the water evaporates from the sheets in the oven, voids are created within the sheets. During the subsequent activation of the heater, resulting in a reaction between the zinc and oxygen, the voids provide the porosity required to contact the zinc in an efficient manner.
The wet process has at least one key advantage in that it yields a heater sheet with sufficient structural integrity that it can be handled, placed, and utilized in a variety of ways. However, while creating a satisfactory heater, the wet process is time consuming in both preparation and drying, with the drying being the primary bottleneck in the production process. The additional time lowers production throughput and increases costs.
The alternative to the wet process is a dry process in which water is not, or is substantially not, used to produce the heater. However, there has not been a dry process for manufacturing a heater developed which can match the mechanical integrity and performance of a wet process heater.
Therefore, it would be advantageous if an oxygen activated or chemical heater could be manufactured using a dry process that substantially or completely removes water and any necessity to dry the heater once constructed.
It would also be advantageous to create a thermoformable article which is integrated with a heater in a manner which allows for more efficient exchange of heat between the heater and the article, and which insures that the entire article is heated uniformly, as quickly as possible.
The present invention is provided to solve these and other issues.
The present invention is directed to a heater and an article having a heater embedded within the article. The heater may be an oxygen activated or chemical heater which is manufactured using a dry process, resulting in a heater which has a performance which matches that of a heater manufactured using a wet process.
According to one aspect of the invention, an article capable of being heated is provided. The article is formed using a material which includes at least one cavity formed therein. The article further includes at least one heater which is embedded in at least one of the plurality of cavities formed in the material. The article finally has a sheet of porous material operatively engaged with the material so that the at least one cavity is covered by the sheet of porous material and the heater material is held therein. In order to maximize surface area and provide the necessary cavities, the material may be formed in a specific configuration or manner, like for example, a honeycomb configuration.
The material forming the article may be a non-thermoformable material or a thermoformable material with any heat generated by the heater making the thermoformable material moldable. The material may also be a woven or non-woven material.
The heater included with the article may also be a heater mix forming a chemical or oxygen activated heater. At least a portion of the heater mix may be embedded in one, a portion, or all of the plurality of cavities. These cavities serve to confine the heater mix and during preparation and use. For example, if the article is cut or trimmed subsequent to activation the amount of heater mix available to be released is minimized. The cavities also provide additional surface area for the transfer of the heat to the article. The heater mix may further include an electrolyte being included therein in order to trigger activation. The article may be sealed within an airtight container in order to prevent oxygen or some other chemical from contacting the heater, and may include an insulator material which substantially surrounds and insulates the thermoformable material when thermoformable material is used.
The heater may also or alternatively be activated using one or more methods. For example, the heater may be activated using microwaves or an induction process.
When constructed as a chemical or oxygen activated heater using a dry process, the heater mix may include zinc, carbon, and binder, as well as some amount of water less than 2% of the total weight of the heater. The heater mix may also include an electrolyte, a binder, and/or a filler. The heater mix preferably has a density in the range of 0.5 g/cm3 and 1.8 g/cm3.
According to another aspect of the invention, the article may be trimmable or scalable while retaining a substantial portion of any heater embedded in the article.
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 to embodiments in many different forms, there is described in detail herein, preferred embodiments of the invention with the understanding that the present disclosures are to be considered as exemplifications of the principles of the invention and are not intended to limit the broad aspects of the invention to the embodiments illustrated.
Article 10 further includes at least one heater 16 (shown in
In order to hold in heater(s) 16 or any portion of heater mix, article 10 may further include at least one sheet of porous material 18 which may substantially cover and be placed over material 12, over top of cavities 14. The sheet of porous material may be constructed to allow one or both of oxygen and electrolyte fluid to pass through the sheet and reach the article or heater as required. In addition to allowing oxygen and electrolyte through, the porous sheet of material may allow for the article to be trimmed along axis n (the narrow axis of the article, for example) while the at least one cavity or the plurality of cavities retain a substantial amount of the heater located in the portion of the article to be used. Retaining a substantially portion of the heater, like for example 95% or more, will allow for the trimmed article to generate any required or desired amount of heat for the remaining portion of the article. The scalability will allow for articles to be designed and then sized on site or when needed, rather than having to create custom sized articles. When paired with thermoformable material as will discussed further herein, a single article like a splint may be provided which can be sized and formed to match a substantial number of individuals rather than the need to buy a custom sized splint or carry multiple splints having different sizes.
As also shown in
The material utilized in the article may be woven and/or non-woven material, and may be either thermoformable or non-thermoformable material, depending on the particular article. In one embodiment of the present invention, material 12 may be a thermoformable material which may become moldable or malleable in response to heat generated by heater(s) 16 once the heater(s) are activated within article 10. Thermoformable material which may be used as the material forming a portion of the article may include, for example, poly(lactic acid), ethylene vinyl acetate, poly(caprolactone), poly(hydroxybutyrate), polyethylene, polypropylene, polystyrene, and any combinations thereof. It is contemplated that the thermoformable material may optionally contain fillers to minimize cost and/or improve mechanical properties such as modulus. A filler that can improve the thermal conductivity of the material may also be employed. Where thermoformable material is used for the material, the thermoformable material and heater(s) should be configured such that the thermoformable material is heated to a moldable state by the heater in approximately 90 seconds. Once heated, the temperature of the article and heater should drop below the temperature required to mold the thermoformable material in less than 10 minutes from the time of activation. Within ten minutes of the activation of the heater, the heat produced by the heater and retained within the article should be lowered to a point where the material is no longer moldable and is in a substantially static, molded position wherein the article has returned to a desired level or rigidity.
Though a portion of a heated article is shown in
Depending on the use of the article and the material and desired properties, the embedded heater(s) may have different characteristics and forms. For example, if the primary purpose of the heater and article is to provide heat to a body, the heater(s) embedded in one or more cavities within the article may be configured and designed to remain activated for a longer period of time. However, if the material used in the article is thermoformable and the article is intended as a thermoformable article, or if the heater is only intended to provide heat for a short amount of time, the heater may quickly increase and decrease heat production. The quick increase and decrease in temperature may allow any thermoformable material to reach the moldable temperature and allow the material to cool in a substantially formed position and state quickly.
Whether the material is thermoformable or not, heater 16 may be constructed as a heater mix or a chemical mix which may react when introduced to additional chemicals or stimuli to generate heat. For example, heater 16 may be constructed as a heater mix which acts as an oxygen activated heater which is manufactured using a substantially dry process. Where an oxygen activated heater is used in article 10, an exterior container or pouch 22 (shown in
In order to manufacture an oxygen activated heater or heater mix using a dry process, a combination of chemicals or compounds may be mixed and combined. The heater mix may be, for example a mixture having approximately 70.0%-90.0%, and more specifically approximately 80.0%, zinc or other chemical which is reactive to oxygen, approximately 5.0%-15.0% carbon, approximately 0.0%-20.0% polytetrafluoroethylene (“PTFE”) acting as an optional binder, and approximately 0.0%-5.0% water with no more than 5% water. A filler may be optionally added to the mix to increase the density of the heater mix. The combination of zinc or other oxygen reactive chemicals, carbon, any optional binder, any optional filler, and any water should be within the bulk density range of 0.5-2.0 g/cm3.
While zinc is the preferred active chemical within the heater because of its ability to quickly provide high amounts of heat once exposed to oxygen and activated, it is contemplated that other chemicals may be utilized, including but not limited to, aluminum, copper, or iron. For the optional binder, rather than, or in addition to, PTFE, polyethylene may be used. When an optional filler is included to alter the density of the heater mix, the optional filler may be sawdust, wood pulp, paper products, cotton linters, ground seed or nut hulls or products, expanded perlite, vermiculite, diatomaceous earth, open-cell polyurethane foam, poly(acrylic acid), hollow beads or spheres, or some combination thereof.
Each of the chemicals or compounds may be provided into a mixer, like for example a rotary mixer, and mixed for a period of time in order to combine each component. Since the mixture is constructed using a completely or a substantially dry process, there is no need to dry the mixture in an oven.
In order for the heater to activate once oxygen is introduced, the heater mix may include an electrolyte which may be added to the mix once the chemicals and compounds are combined. For heaters which are not manufactured with an electrolyte, an electrolyte may be added after the heater is placed, like for example in a cavity of an article as discussed herein. The electrolyte may be added directly to the heater(s), or may be added through a porous member or the like after the porous member is fit over the heater and any article which includes a heater. Whether included in the heater mix or later added, electrolytes which may be used include, but are not limited to, sodium chloride, sodium bromide, potassium chloride, potassium bromide or potassium hydroxide. The preferred amount of electrolyte to be added to the heater mix ranges from 15%-40% by weight of the heater mix. For example, for 10 g of heater mix, it is preferable to have 30% loading, which requires approximately 3 g of electrolyte. The concentration of the electrolyte used with the heater mix should range from 1%-40% by weight of solution.
As with any heater or heater mix, the amount of electrolyte added to each particular cavity or a region of cavities may vary. Following the example above, the amount of electrolyte added to heater embedded in cavities located in a perimeter portion or edge, like for example perimeter 21, may be greater than the amount of electrolyte added to heater embedded in cavities located in a middle portion or area, like for example middle 23. The amount of electrolyte added to each cavity or region of cavities may be selected based upon the amount of heater in each cavity, or to incur a desired result or heating time for a particular cavity or region in the article. Rather than add more or less electrolyte to a particular cavity or region, the concentration of the electrolyte added to any particular cavity or region of cavities may be varied. Electrolyte having a higher concentration, like for example 40% by weight of solution, may be added to cavities along perimeter 21, while electrolyte having a concentration of 20% by weight of solution may be added to cavities located in middle 23. Once the heater mix is combined and any electrolyte is added, if the heater mix is to be utilized as a standalone heater without an article, the heater may be packaged in an air impermeable or airtight container. The container may include internal dividers or compartments to prevent the movement of the heater mix, and may be constructed from polylactic acid), ethylene vinyl acetate, poly(caprolactone), poly(hydroxybutyrate), polyethylene, polypropylene, polystyrene, or combinations thereof. At least one portion of any package housing a standalone heater should have a material with a thermal conductivity of at least 10 W/mK in order to provide for satisfactory heat transfer once the heater is activated. The package should also provide for a tear away or other access point to allow the heater mix to be exposed to oxygen in order to activate the heater. The standalone heater packaging may also include at least one attachment element which will allow the heater to attach to a body or device. The attachment element may be a physical element like a clip or pin which permits the heater to be attached directly to a body or device, or may be an adhesive or other coating which allows the heater to be coupled to a body or device. The packaging may also be flexible in order to allow for the manipulation of the heater to achieve a particular shape or configuration.
If the heater mix is instead intended for use in an article like those discussed herein, the article may then be constructed as follows. It should once again be understood that though a thermoformable splint will be used as an example, non-thermoformable materials, and articles other than a splint may be constructed in a similar manner. First the material may be designed and configured, like for example a thermoformable material formed as a splint with a honeycomb surface. Next, the heater mix may be used to cover and fill the honeycomb surface or configuration, placing the heater mix into each of the cavities. Excess heater mix may be removed so that the heater mix is uniformly formed within the cavities. The sheet of porous material may then be placed over the honeycomb surface and adhered thereto in order to lock in the heater mix and prevent it from escaping. If the heater mix does not include any electrolyte, electrolyte may then be added to the heater mix through the sheet of porous material. The article may then have any insulation attached to the article, and then be packaged in an air impermeable or airtight container until ready for use.
In operation, once the article is removed from the air impermeable or airtight packaging, the combination of the heater mix and electrolyte will cause the heater to begin heating. If the material which forms part of the article is not a thermoformable material, the heat will be transmitted to and through the article. If the material forming part of the article is a thermoformable material, the thermoformable material should be provided with enough heat to make the material moldable in a very short period of time, preferably 180 seconds or less, more preferably 90 seconds or less. For example, if the article is a splint, the splint will preferably become moldable in about 90 seconds so that it can quickly be formed to a body. The heat generated by the heater should quickly dissipate and the heater should then cool off and put the article in a substantially static, formed shaped, as desired. Since the heater is embedded within the article, the heat transfer will be quicker, more efficient, and more uniform, throughout the material and article, allowing for better and quicker molding of the article.
While in the foregoing there has been set forth various embodiments of the invention, it is to be understood that the present invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein. While specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the characteristics of the invention and the scope of protection is only limited by the scope of the accompanying claims.
