Method for manufacturing thermal insulation material

Abstract

A method for manufacturing an insulating material includes providing an inner wall (210) configured to at least partially define a heating zone (144) for receiving an aerosol-generating material and including a heating material heatable by the penetration of a varying magnetic field, and providing an outer wall (212) at least partially surrounding the inner wall along its length, such that an insulating region (224) is formed between the inner and outer walls. Such a method further includes applying a portion of a first bonding material (252) to the inner wall at atmospheric pressure, applying a portion of a second bonding material (250) to the outer wall at atmospheric pressure, evacuating the insulating region to a pressure below atmospheric pressure, and closing the insulating region by bonding the first and second bonding materials to each other. An adhesive (254) or bonding members (326, 328) may also be used to close the insulating region.

Description

[Technical field]

[0001] The present invention relates to a method of manufacturing insulation for use in an aerosol delivery device, and to the insulation material produced thereby.

[0002] Smoking articles, such as cigarettes, cigars, etc., burn tobacco during use to produce tobacco smoke. Attempts have been made to provide an alternative to these tobacco-burning articles by creating products that release compounds without combustion. Examples of such products include heating devices that release compounds by heating, rather than burning, a material. The material may be, for example, tobacco or other non-tobacco products, which may or may not contain nicotine. Overview

[0003] According to a first aspect of the present disclosure, there is provided a method of manufacturing an insulating material, the method comprising: providing an inner wall configured to at least partially define a heating zone for receiving an aerosol-generating material, the inner wall comprising a heating material that is heatable by the penetration of a varying magnetic field; providing an outer wall at least partially surrounding the inner wall along its length, an insulating region formed between the inner wall and the outer wall, the inner wall and the outer wall comprising different materials; attaching a portion of a first bonding material to the inner wall under atmospheric pressure; attaching a portion of a second bonding material to the outer wall under atmospheric pressure; evacuating the insulating region to a pressure below atmospheric pressure; and closing the insulating region by bonding the first bonding material and the second bonding material to each other.

[0004] According to a second aspect of the present disclosure, there is provided a method of manufacturing insulation material, the method comprising the steps of: providing an inner wall configured to at least partially define a heating zone for receiving at least a portion of an article including smoking material, the inner wall including a heating material that is heatable by the penetration of a varying magnetic field; providing an outer wall surrounding the inner wall at least partially along its length, an insulation region being formed between the inner wall and the outer wall; evacuating the insulation region to a pressure below atmospheric pressure; and closing the insulation region by joining the inner wall and the outer wall using an adhesive.

[0005] According to a third aspect of the present disclosure, there is provided a method of manufacturing an insulating material, the method comprising: providing an inner wall configured to at least partially define a heating zone for receiving at least a portion of an article including smoking material, the inner wall including a heating material that is heatable by the penetration of a varying magnetic field; providing an outer wall at least partially surrounding the inner wall along its length, an insulating region being formed between the inner wall and the outer wall; providing one or more joining members; joining each of the one or more joining members to the inner wall; evacuating the insulating region to a pressure below atmospheric pressure; and closing the insulating region by joining at least one of the one or more joining members to the outer wall.

[0006] According to a fourth aspect of the present disclosure, there is provided an insulation material produced according to any of the first three aspects of the present disclosure.

[0007] According to a fifth aspect of the present disclosure, there is provided a non-combustion aerosol delivery device comprising: an insulation material according to the fourth aspect of the present disclosure; and a magnetic field generator that, in use, generates a varying magnetic field that penetrates an inner wall to heat the inner wall.

[0008] According to a sixth aspect of the present disclosure, there is provided a non-combustion aerosol delivery system comprising: an apparatus according to the fifth aspect of the present disclosure; and an aerosol-generating material that, in use, is at least partially disposed within a heated zone of an inner wall of the insulation.

[0009] Further characteristics and advantages of the present invention will become apparent from the following description of preferred embodiments of the invention, given by way of example only, with reference to the accompanying drawings, in which:

[0010] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying drawings, in which: [Brief description of the drawings]

[0011] [Figure 1] 1 is a schematic cross-sectional view of an exemplary aerosol delivery device. [Diagram 2] 2 is a schematic cross-sectional view of an exemplary insulation material for use in the apparatus of FIG. 1. [Diagram 3] FIG. 3 is a cross-sectional view taken along line AA in FIG. 2. [Figure 4] 1 is a schematic cross-sectional view of a further example of insulation for use in an aerosol delivery device, illustrating how a bonding material can be used to connect an outer wall of the insulation to an inner wall of the insulation. [Diagram 5] FIG. 2 is a schematic cross-sectional view of another example of insulation for use in an aerosol delivery device, illustrating how an adhesive can be used to connect an outer wall of the insulation to an inner wall of the insulation. [Figure 6] FIG. 2 is a schematic cross-sectional view of another example of insulation for use in an aerosol delivery device, illustrating how an outer wall of the insulation is connected to an inner wall of the insulation using a joining member in the form of an end cap. [Figure 7] 7 is a schematic cross-sectional view of another example of an insulating material, illustrating how the insulating material of FIG. 6 can be positioned relative to the heating coil and magnetic shield of the aerosol delivery device. Detailed Description

[0012] As used herein, the term "aerosol-forming material" includes materials that, when heated, provide volatile components, typically in the form of an aerosol. Aerosol-forming materials include any tobacco-containing material, and may include, for example, one or more of tobacco, tobacco derivatives, expanded tobacco, reconstituted tobacco, or tobacco substitutes. Aerosol-forming materials may also include other non-tobacco products, which may or may not contain nicotine, depending on the product. Aerosol-forming materials may be in the form of, for example, a solid, liquid, gel, wax, etc. Aerosol-forming materials may also be, for example, a combination or mixture of materials. Aerosol-forming materials may also be referred to as "smoking materials."

[0013] Devices are known that use an aerosol generator to generate an aerosol from an aerosol-generating material. One particularly common way to generate an aerosol is by heating the aerosol-generating material. In such devices, the aerosol generator is a heater that heats the aerosol-generating material to volatilize at least one component of the aerosol-generating material, typically forming an inhalable aerosol without burning or combusting the aerosol-generating material. Such devices are sometimes described as "aerosol delivery devices," "non-combustion heated devices," "tobacco heating product devices," or "tobacco heating devices." There are also so-called e-cigarette devices, which typically vaporize aerosol-generating material in liquid form that may or may not contain nicotine. The aerosol-generating material may be in the form of, or formed as part of, a rod, cartridge, cassette, or the like that can be inserted into the device. The aerosol generator for volatilizing the aerosol-generating material may be provided as a "permanent" part of the device, or may be combined with the aerosol-generating material in a replaceable or consumable component. While this disclosure focuses on aerosol generators that are heaters, it should be understood that alternative methods of generating aerosols from aerosol-generating materials may also be used.

[0014] The aerosol delivery device can accept and heat an article that includes an aerosol-generating material. An "article" in this context is a component that, in use, includes or contains an aerosol-generating material that, in use, is heated to volatilize the aerosol-generating material, and optionally other components. A user can insert the article into the aerosol delivery device before the article is heated and generate an aerosol, which is then inhaled by the user. The article can be, for example, of a predetermined or specific size that is configured to fit into a heating chamber of the device that is dimensioned to accept the article. Alternatively, the aerosol-generating material can simply be placed freely or without constraint into the heating chamber of the device; for example, uncured tobacco leaves can be used in this manner.

[0015] Induction heating is a process in which an electrically conductive object is heated by penetrating a fluctuating magnetic field into the object. This process is described by Faraday's law of induction and Ohm's law. An induction heater may comprise an electromagnet and a device for passing a fluctuating current, such as an alternating current, through the electromagnet. When the electromagnet and the object to be heated are appropriately positioned relative to one another so that the fluctuating magnetic field generated by the electromagnet penetrates the object, one or more eddy currents are generated inside the object. The object has a resistance to the flow of electric current. Thus, when such eddy currents are generated in the object, they flow against the electrical resistance of the object, causing the object to heat up. This process is called Joule heating, Ohmic heating, or resistive heating. Objects that can be inductively heated are known as susceptors.

[0016] Magnetic hysteresis heating is a process whereby an object made of a magnetic material is heated by subjecting the object to a varying magnetic field. A magnetic material can be thought of as containing many atomic-scale magnets, i.e., magnetic dipoles. When a magnetic field is applied to such a material, the magnetic dipoles align themselves with the magnetic field. Thus, when a varying magnetic field, such as an alternating magnetic field produced by an electromagnet, is applied to a magnetic material, the orientation of the magnetic dipoles changes with the applied varying magnetic field. This reorientation of the magnetic dipoles generates heat in the magnetic material.

[0017] If an object is both conductive and magnetic, then the penetration of a varying magnetic field into the object can result in both Joule heating and magnetic hysteresis heating in the object. Furthermore, the magnetic field can be strengthened using magnetic materials, which can enhance Joule heating and magnetic hysteresis heating.

[0018] In each of the above processes, because heat is generated within the object itself, rather than by thermal conduction from an external heat source, rapid temperature rise and more uniform heat distribution in the object can be achieved, particularly by selecting the appropriate object material and geometry, and the appropriate magnitude and orientation of the varying magnetic field relative to the object. Furthermore, induction heating and magnetic hysteresis heating do not require a physical connection to be made between the source of the varying magnetic field and the object, which may allow greater design freedom and control over the heating profile, and may result in lower costs.

[0019] FIG. 1 shows a schematic cross-sectional view of an aerosol delivery device 100 according to one example of the invention. FIGs. 2 and 3 show schematic cross-sectional views of an exemplary insulation 102 for use in the aerosol delivery device 100. The insulation 102 is shown in FIG. 1 in a simplified form for clarity. The insulation 102 of the aerosol delivery device 100 is configured to receive an aerosol-generating material (not shown) to be heated by virtue of it comprising a heating chamber or zone 144. The aerosol-generating material may be inserted into an opening of the heating chamber 144 of the aerosol delivery device 100. The aerosol delivery device 100 includes a magnetic field generator 106 for generating a varying magnetic field in use, and a housing 108 for housing each of the components of the aerosol delivery device 100.

[0020] In this example, the magnetic field generator 106 comprises a power source 114 and a device 118 for passing a varying current, such as an alternating current, through the two-part coils 116a, 116b. In some examples, such as that shown in FIG. 1, the magnetic field generator 106 is further connected to a controller 120 and a user interface 122 for a user to operate the controller 120.

[0021] The power source 114 may be a rechargeable battery (such as a lithium ion battery), a non-rechargeable battery, a capacitor, a battery-capacitor hybrid, or a connection to a mains power source.

[0022] The coils 116a, 116b may take any suitable form, including a single coil having two parts, with a single part coil being an alternative. In the example shown in FIG. 1, the two-part coils 116a, 116b are helical coils made of a conductive material such as copper. In some examples, the coils 116a, 116b may be flat coils; that is, the coils may be pseudo-two-dimensional helices. In some examples, the coils may comprise Litz wire.

[0023] Aerosol delivery device 100 includes an air inlet (not shown) that fluidly connects the interior of the apparatus with the exterior of aerosol delivery device 100. During use, a user may be able to inhale the volatile component(s) of the aerosol-generating material. Air may be drawn into aerosol delivery device 100 via the air inlet as the volatile component(s) are removed from the aerosol-generating material.

[0024] The insulation 102 is shown in more detail in Figures 2 and 3 and includes an inner wall 110 and an outer wall 112. The inner wall 110 is a heating element that includes or is made of a heating material that can be heated by the penetration of a varying magnetic field. In one example, the inner wall 110 may be formed of mild steel, which is inexpensive, easy to machine, and is a susceptor. In another example, the inner wall 110 may be formed of ferritic stainless steel, which is easy to machine, has good corrosion resistance, and is a susceptor. However, nickel-cobalt-iron alloys such as Kovar® may also be used. A heating chamber or heating zone 144 is surrounded by the inner wall 110. As a result, the inner wall 110 at least partially defines the heating chamber / zone 144. During use, an aerosol-generating material to be heated is received in the heating chamber / zone 144 within the inner wall 110. 2 and 3, the insulation 102 is shown as being substantially cylindrical with a circular cross-sectional shape. In other examples, the insulation 102 can have a different cross-sectional shape.

[0025] 2 and 3, the illustrated example insulation 102 includes an insulation region 124 bounded by and disposed between an inner wall 110 and an outer wall 112. In the depicted example, the insulation region 124 surrounds the inner wall 110, and the outer wall 112 surrounds the insulation region 124, as clearly shown in FIG. 3. The insulation region 124 is evacuated to a subatmospheric pressure that would be expected to exist in an area outside the insulation region. In some examples, the subatmospheric pressure may be as low as 100 psi. -1Torr or less. Providing an insulating region 124 with a pressure lower than atmospheric pressure insulates the inner wall 110 and the heating chamber / zone 144 from the outer wall 112 and the housing 108 to limit heat transfer from the inner wall 110 and the heating chamber / zone 144 to the remainder of the aerosol delivery device 100 (outside the heating chamber / zone 144). This heat transfer limitation is advantageous because other components of the aerosol delivery device 100, such as the power source 114, may be susceptible to increased temperatures. For example, it is well known that batteries can be damaged or even dangerous if exposed to high temperatures. Furthermore, heat transfer to the housing 108 of the aerosol delivery device 100 may cause discomfort or even injury to the user during use.

[0026] The pressure in the insulating region 124 may be in the range of 10-1 to 10-7 torr. In some examples, the pressure in the insulating region 124 may be considered a vacuum. The inner and outer walls 110, 112 of the insulation 102 are strong enough to withstand any forces acting against them due to a pressure differential between the insulating region 124 and the regions outside the inner and outer walls 110, 112, thereby preventing the insulation 102 from collapsing inward. Gas absorbing materials may be used in the insulating region 124 to maintain or help create a relatively low pressure in the insulating region 124.

[0027] Providing insulation region 124 at a pressure lower than atmospheric pressure is particularly advantageous because it allows for very effective insulation to be achieved in a much smaller area than may be possible with alternative insulation options. This allows for the overall size of aerosol delivery device 100 to be kept to a minimum without compromising the insulation of heating chamber / zone 144. Furthermore, when inner wall 110 serves as both the heating element and the wall of insulation 102, the overall size and weight of aerosol delivery device 100 can be reduced since there is no need to include a separate heating element and separate insulation components. Inner wall 110 can be conveniently heated by induction heating and therefore can serve as both the heating element and the wall of insulation 102. Induction heating advantageously does not require a physical connection to be provided between the source of the varying magnetic field and the heating element, thereby eliminating the need for wires or any other physical connections between the power source and the heating element.

[0028] FIG. 3 shows a cross section of line AA in FIG. 2. FIG. 2 and FIG. 3 are not drawn to scale. In FIG. 2, the outer wall 112 is shown extending along the entire length of the inner wall 110. However, in the alternative, the outer wall 112 may extend only partially along the length of the inner wall 110. That is, the outer wall 112 may extend along a portion of the inner wall 110 such that insulation may occur only around a portion of the inner wall 110. Providing an outer wall 112 that extends only partially along the length of the inner wall 110 may allow the overall size of the aerosol delivery device 100 to be further reduced. Although the outer wall 112 and the inner wall 110 are shown as being coaxial with each other, this is not required.

[0029] As shown in Fig. 1, the coils 116a, 116b surround at least a portion of the insulation 102. Specifically, the coils 116a, 116b surround at least a portion of the outer wall 112 of the insulation 102. As shown in Figs. 1 and 7, a magnetic shield 140 is provided around at least a portion of the coils 116a, 116b or 116. The magnetic shield 140 is used to reduce or avoid interaction between the magnetic field generated by the magnetic field generator 106 and something other than the heating element, i.e., the inner wall 110. The magnetic shield can be made of any material(s), such as a ferrite material, that is suitable for containing a magnetic field.

[0030] In some examples, the outer wall 112 is formed from an insensitive, non-conductive material so that it is not significantly heated by induction heating when exposed to a fluctuating magnetic field. In some examples, the outer wall 112 includes one or more of an insensitive metallic material, or a plastic, glass, or ceramic material. Providing the outer wall 112 from an insensitive material means that when a fluctuating current, such as an alternating current, is passed through the coils 116a, 116b, the inner wall 110 of the insulation 102 is heated, whereas the outer wall 112 is not heated by induction heating. Thus, the efficiency of the system and the thermal management within the system can be improved since energy is not wasted heating the outer wall 112 and excessive temperature rise of the outer wall 112 does not have to be suppressed and / or mitigated. Even if the outer wall 112 is heated by the fluctuating current, the inner wall 110 is actually only minimally heated undesirably. This construction also serves to maintain the temperature of the outside of the housing 108, especially at its surface, at a level acceptable for handling by a user. Non-sensitive metals are generally cheap, easy to work and / or machineable, plastics are cheap, easy to mold and tough, and glass is cheap, easy to mold and has good strength, while ceramic materials are strong, tough and lightweight. A suitable plastic material may be a polymer that is thermally and mechanically stable up to at least 250°C, and in some cases at least 320°C. An example of such a polymer is polyetheretherketone (PEEK). A suitable glass material may be borosilicate glass, which has a low coefficient of thermal expansion making it particularly thermal shock resistant. A suitable ceramic material may be zirconia. Composite materials including two or more of the above listed materials, such as glass-reinforced plastic, may enable beneficial properties of the combined materials.

[0031] In order to produce an insulation with a closed insulation area, which is necessary if the insulation area is to be maintained at a pressure lower than atmospheric pressure, the inner and outer walls of the insulation must be connected. As mentioned above, it is advantageous that the inner wall is heatable by penetrating a fluctuating magnetic field, while the outer wall is not. Thus, the inner wall comprises a material that is a susceptor and the outer wall comprises a material that is not a susceptor. Direct joining of dissimilar materials under conditions of pressure lower than atmospheric pressure using methods such as brazing, welding, soldering, etc. can be difficult to manufacture. For example, many conventional welding techniques cannot be performed in a vacuum, since they require the presence of an inert gas. The methods described below according to the first, second and third aspects of the present disclosure solve this problem by providing an improved method of connecting the inner and outer walls comprising dissimilar materials when producing an insulation comprising an outer and inner wall such that a low pressure insulation area is included.

[0032] FIG. 4 shows schematic steps of a method for manufacturing an insulating material 202 according to a first aspect of the disclosure. The first step of the method, illustrated at the bottom of FIG. 4, includes providing an inner wall 210 and an outer wall 212. The inner wall 210 is configured to include a heating material that is heatable by penetrating a varying magnetic field such that it at least partially defines a heating chamber or heating zone for receiving an aerosol-generating material (not shown). In some examples, the inner wall 210 includes mild steel. Mild steel is an advantageous material because it is inexpensive, easy to machine, and is a susceptor. In other examples, the inner wall 110 includes ferritic stainless steel. Ferritic stainless steel is an advantageous material because it is easy to machine, has good corrosion resistance, and is a susceptor. The outer wall 212 is configured to surround the inner wall 210 at least partially along its length such that an insulating region 224 is formed between the inner wall 210 and the outer wall 212. To avoid heating of the outer wall 212 by the fluctuating magnetic field applied to heat the inner wall 210, the outer wall 212 comprises a material different from that of the inner wall 210. As discussed above, in some examples, the outer wall comprises one or more of an insensitive metal material, or a plastic, glass, or ceramic material. Insensitive metals are generally cheap, easy to work with, and / or machineable, plastics are cheap, easy to form, and durable, and glass is cheap, easy to form, and has good strength, while ceramics are strong, durable, and lightweight. Insensitive metals, plastics, glasses, and ceramics are all not significantly heatable by the penetration of the fluctuating magnetic field. A suitable plastic material may be a polymer that is thermally and mechanically stable up to at least 250° C., and in some cases at least 320° C. An example of such a polymer is polyetheretherketone (PEEK). A suitable glass material may be borosilicate glass, which has a low coefficient of thermal expansion making it particularly thermal shock resistant. A suitable ceramic material may be zirconia. Composite materials including two or more of the materials listed above, such as glass reinforced plastic, may allow for beneficial properties of the combined materials.

[0033] The second step of the method according to the first aspect of the disclosure is shown by arrow A in FIG. 4. Under normal atmospheric pressure, a portion of the first bonding material 250 is attached to the outer wall 212 and a portion of the second bonding material 252 is attached to the inner wall 210. The first bonding material 250 and the second bonding material 252 are made of similar materials. However, each of the first bonding material 250 and the second bonding material 252 is a different material from the material that the inner wall 210 and the outer wall 212 comprise. In some examples, the first bonding material 30 and the second bonding material 252 are identical to each other. In some examples, the first bonding material 250 and the second bonding material 252 are attached to the outer wall 212 and the inner wall 210, respectively, by brazing, welding or soldering. Brazing forms joints with good strength and can be used to join closely fitting parts, welding forms joints with very high strength, and soldering forms joints with reasonable strength while using much lower heating temperatures than would be required for either brazing or welding. The first joining material 250 may be joined to the outer wall 212 by a method different from the method used to join the second joining material 252 to the inner wall 210, or the method used may be the same.

[0034] Advantageously, the dissimilar materials of the outer wall 212 and the first bonding material 250, and the inner wall 210 and the second bonding material 252, respectively, are bonded under normal atmospheric pressure. As discussed above, it is easier to bond dissimilar materials under normal atmospheric pressure than under pressures below normal atmospheric pressure.

[0035] The third step of the method according to the first aspect of the disclosure is shown in FIG. 4 by arrow B. The insulating region 224 is evacuated to a pressure below atmospheric pressure. The insulating region 224 is then closed by bonding the first bonding material 250 and the second bonding material 252 together. As discussed above, the first bonding material 250 and the second bonding material 252 include similar materials, and in some examples include the same materials. In some examples, the first and / or second bonding materials are silver eutectic brazing materials. Silver eutectic alloys are suitable for a wide range of brazing applications. Silver eutectic alloys may also be effective for bonding dissimilar materials, as required in the second step of the method described herein, and may be used in vacuum conditions, as required in the third step of the method.

[0036] To form and maintain the insulating region 224 at subatmospheric pressure, the insulating region must be closed under subatmospheric pressure. The method according to the first aspect of the present disclosure has the advantage that only similar materials are bonded together under subatmospheric pressure, as discussed above. As previously mentioned, this bonding is a simpler manufacturing step than bonding dissimilar materials under subatmospheric pressure. Thus, the method according to the first aspect of the present disclosure reduces the complexity of manufacturing the insulating material 202.

[0037] In some examples, when the insulating region 224 is evacuated to a pressure below atmospheric pressure, the region outside the insulating region 224 is also evacuated to a pressure below atmospheric pressure. Such evacuation can be accomplished, for example, by performing the second step of the method according to the second aspect of the present disclosure in a vacuum chamber.

[0038] In some cases, pressures below atmospheric pressure are 10 -1 Torr or less. As previously discussed, reducing the pressure in the insulating region improves the insulating properties of the insulating region. -1 A pressure of less than Torr provides good insulating properties for the enclosed insulating region 224 .

[0039] The method shown in FIG. 4 and discussed above includes a step of bonding the first bonding material 250 to the second bonding material 252 at both ends of the insulation 202 under low pressure conditions. However, it should be understood that bonding more than one first bonding material 250 and second bonding material 252 by this method is not necessary when manufacturing a single insulation 202. According to the first aspect of the present disclosure, the method of bonding the first bonding material 250 and second bonding material 252 is performed under low pressure conditions to close the insulation area 224, and such a step can also be performed only at one end of the insulation 202, the other end having been initially bonded under normal atmospheric conditions. Thus, the method according to the first aspect of the present disclosure only requires that the special conditions outlined above (bonding the first bonding material 250 and second bonding material 252 under low pressure conditions) be used for the final bonding performed to close the insulation area 224, but the use of this method to perform other bonds is of course not excluded.

[0040] Figure 5 shows a method of manufacturing insulation 202 according to a second embodiment of the present disclosure. The first step of the method shown on the left side of Figure 5 involves providing an inner wall 210 and an outer wall 212, similar to that described above with respect to the first embodiment of the present disclosure.

[0041] The second step of the method according to the second aspect of the disclosure is shown on the right side of FIG. 5. The insulating area 224 is evacuated to a pressure lower than atmospheric pressure. The insulating area 224 is then closed by bonding the outer wall 212 to the inner wall 210 using an adhesive 254. Adhesives have the advantage of being able to bond a wide range of materials, whether they are similar or dissimilar to each other. In general, the bonds formed by adhesives exhibit good strength, toughness, and resistance to chemical and thermal degradation. By using adhesive 254, the method according to the second aspect of the disclosure avoids the difficulties of bonding dissimilar materials under low pressure conditions that may arise when using brazing, welding or soldering. Examples of suitable adhesives may include two-part epoxies, one-part epoxies, or acrylic adhesives.

[0042] In some examples, when the insulating region 224 is evacuated to a pressure lower than atmospheric pressure, the region outside the insulating region 224 is also evacuated to a pressure lower than atmospheric pressure. Such evacuation can be achieved, for example, by performing the second step of the method according to the second aspect of the present disclosure in a vacuum chamber. This has the advantage that the adhesive 254 can be applied under conditions where there is a small pressure difference between the insulating region 224 and the region outside the insulating region 224. This can allow the adhesive 254 to be used to bond the inner wall 210 and the outer wall 212 more easily than if the region outside the insulating region 224 was maintained at atmospheric pressure. For example, the lack of a pressure difference can allow the adhesive to be applied more accurately. Furthermore, while adhesives are typically applied in a liquid state and require at least a short time to solidify and form a bond, removing the pressure difference between the insulating region 224 and the region outside the insulating region 224 can allow the adhesive to solidify and become stronger without being hindered by a pressure difference that would otherwise be present.

[0043] Some adhesives require time to cure after application in order for the adhesive bond to be effective and / or stronger. In instances where such adhesives are used, curing may be accelerated by evacuating the area in which the adhesive resides to a pressure below atmospheric pressure. This is particularly the case for vacuum-curing adhesives. Such adhesives may be cured by application of heat and / or ultraviolet light. Such vacuum curing may be accomplished by ensuring that the pressure within and outside of the insulating region 224 is maintained at a pressure below atmospheric pressure.

[0044] As with the first aspect of the present disclosure (discussed in more detail above and shown in FIG. 4), it is not essential that the method according to the second aspect of the present disclosure is used to bond the inner wall 210 and the outer wall 212 at both ends of the insulation 202 as shown in FIG. 5. For example, the inner wall 210 and the outer wall 212 may first be bonded at one end of the insulation 202 under normal atmospheric conditions, after which the insulation area 224 is evacuated and the inner wall 210 and the outer wall 212 are bonded at the second end using adhesive 254 to close the insulation area 224. Thus, as with the first aspect, the method according to the second aspect of the present disclosure only requires that the final bonding to close the insulation area 224 is performed according to the special conditions outlined above (evacuating the insulation area 224 and then closing the insulation area 224 by bonding the outer wall 212 to the inner wall 210 using adhesive 254), although the use of such a method to perform other bonding is of course not excluded.

[0045] Figure 6 shows a method of manufacturing an insulation 302 according to a third aspect of the disclosure. The first step of the method shown at the bottom of Figure 6 involves providing an inner wall 310 and an outer wall 312 in the same manner as described above with respect to the first and second aspects of the disclosure. One or more joining members are also provided, and in the example illustrated in Figure 6, a first joining member 326 and a second joining member 328 are provided.

[0046] The second step of the method according to the third aspect of the present disclosure is indicated by arrow A in Fig. 6. Under normal atmospheric pressure, the first and second joining members 326, 328 are joined to the inner wall 310. It is expected that the material of the inner wall 310 is different from the material of the first and second joining members 326, 328, which would otherwise be susceptible to heating by application of a magnetic field in the same manner as the inner wall 310. In some examples, the method of joining each of the joining members to the inner wall 310 is brazing, welding, soldering, adhesives, or an interference fit.

[0047] The third step of the method according to the third aspect of the present disclosure is indicated by arrow B in Fig. 6. The insulating region 324 is evacuated to a pressure below atmospheric pressure. The insulating region 324 is then closed by bonding each of the first and second bonding members 326, 328 to the outer wall 312. In some examples, the method of bonding each of the bonding members to the inner wall 310 is brazing, welding, soldering, adhesives, or an interference fit.

[0048] Providing one or more joining members as required by the method according to the third aspect of the disclosure is advantageous because it avoids the requirement that the inner wall 310 and the outer wall 312 must be directly joined to each other. As discussed above, joining dissimilar materials under low pressure conditions can be difficult to manufacture. The material requirements for the inner wall 310 and the outer wall 312 can be quite restrictive, for example, the inner wall 310 must be susceptible to be heated by induction heating, and both the inner wall 310 and the outer wall 312 must be able to support the mechanical stresses caused by maintaining a relatively low pressure in the insulating region 324. The material requirements for the joining member(s) may be less restrictive, thus allowing for the selection of a material that can be more easily joined to the outer wall 312 and / or the inner wall 310. In some examples, the outer wall 312 and the first and second joining members 326, 328 comprise similar or identical materials. Thus, in the method according to the third aspect of the invention, the dissimilar materials of the inner wall 310 and the first and second joining members 326, 328 are allowed to be joined under atmospheric conditions, and then the like materials of the first and second joining members 326, 328 and the outer wall 312 are joined under lower pressure conditions to close off the insulating region 324.

[0049] It should be understood that in instances where more than one joining member is used, only the joining of the final joining member to the exterior wall needs to be performed under low pressure conditions to close the insulation region. For example, if two joining members 326, 328 are used, the first and second joining members 326, 328 can be joined to the interior wall 310 and one of the joining members can be joined to the exterior wall 312, all under normal atmospheric conditions. The insulation region can then be depressurized and the remaining joining member can be joined to the exterior wall 312 to close the insulation region 324. Even joining similar materials under low pressure conditions can present manufacturing difficulties, so performing only one joining in this manner under low pressure conditions can be advantageous.

[0050] The use of one or more joining members disposed between the outer wall 312 and the inner wall 310 may allow at least one of the joints between these components to be an interference fit. An interference fit has the advantage of being simple to manufacture and also avoids the need for heat in the joining process and / or additional materials such as brazing material or adhesives. The use of an interference fit is particularly advantageous in the example where the one or more joining members are end caps, each configured to be disposed at the ends of the outer wall 312 and the inner wall 310. When end caps are used, the external pressure caused by the relatively low pressure in the insulating region 324 helps to secure the joining members in place, and therefore the connection obtained by the interference fit is further secured by this pressure. It should also be noted that when one or more end caps are used, the external pressure also helps to secure any other form of joint between the one or more end caps and the outer wall 312 and the inner wall 310.

[0051] FIG. 7 shows an example of insulation 302 surrounded by a single induction coil 116, which is surrounded by a magnetic shield 140 of an aerosol delivery device, produced by the method of the third aspect of the present disclosure.

[0052] A fourth aspect of the present disclosure describes an insulation material produced by any of the methods described in the previous aspects of the present disclosure. It will be appreciated that by providing an improved method of manufacture, the insulation material produced by the improved method will be more robust than alternative insulation products.

[0053] In a fifth aspect of the present disclosure, an aerosol delivery device is described that comprises an insulation material according to the fourth aspect of the present disclosure and a magnetic field generator that, in use, generates a varying magnetic field that penetrates the inner wall to heat the inner wall. An example of an aerosol delivery device according to the present disclosure is discussed in more detail above in relation to FIG.

[0054] In a sixth aspect of the present disclosure, an aerosol delivery system is described that includes an apparatus according to the fifth aspect of the present disclosure and an aerosol-generating material that, in use, is at least partially disposed within a heated zone of an inner wall of the insulation.

[0055] The above embodiments should be understood as illustrative of the invention. Further embodiments of the invention are envisioned. It should be understood that any feature described with respect to any one embodiment may be used alone or together with other features described, and may also be used together with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Moreover, equivalents and modifications not described above may also be used without departing from the scope of the invention as defined in the appended claims. The following embodiments are disclosed in this specification. (Embodiment 1) 1. A method for producing an insulating material, comprising the steps of: providing an inner wall configured to at least partially define a heating zone for receiving an aerosol-generating material, the inner wall including a heating material that is heatable by the penetration of a varying magnetic field; providing an outer wall surrounding the inner wall at least partially along a length thereof, an insulating region being formed between the inner wall and the outer wall, the inner wall and the outer wall comprising distinct materials; depositing a portion of a first bonding material on the inner wall at atmospheric pressure; applying a portion of a second bonding material to the exterior wall at atmospheric pressure; evacuating the insulating region to a pressure below atmospheric pressure; closing the insulating region by bonding the first bonding material and the second bonding material together; A method comprising: (Embodiment 2) 2. The method of claim 1, wherein when the insulating region is evacuated to a pressure below atmospheric pressure, a region outside the insulating region is also evacuated to a pressure below atmospheric pressure. (Embodiment 3) 3. The method of claim 1 or 2, wherein the portion of the first joining material and the portion of the second joining material are attached to at least one of the inner wall and the outer wall by brazing, welding, or soldering. (Embodiment 4) 4. The method of any one of the preceding claims, wherein the first joining material and the second joining material are joined to each other by brazing, welding, or soldering. (Embodiment 5) 5. The method of any one of the preceding claims, wherein the first joining material and the second joining material comprise a silver eutectic braze material. (Embodiment 6) 1. A method for producing an insulating material, comprising the steps of: providing an inner wall configured to at least partially define a heating zone for receiving at least a portion of an article including smokable material, the inner wall containing a heating material that is heatable by the penetration of a varying magnetic field; providing an outer wall surrounding said inner wall at least partially along its length, an insulating region being formed between said inner wall and said outer wall; evacuating the insulating region to a pressure below atmospheric pressure; closing the insulating region by bonding the inner wall and the outer wall using an adhesive; A method comprising: (Embodiment 7) 7. The method of embodiment 6, wherein the inner wall and the outer wall comprise different materials. (Embodiment 8) 8. The method of claim 6 or 7, wherein when the insulating region is evacuated to a pressure below atmospheric pressure, a region outside the insulating region is also evacuated to a pressure below atmospheric pressure. (Embodiment 9) 9. The method of claim 8, wherein the adhesive is cured while an area outside the insulating area is at a pressure less than atmospheric pressure. (Embodiment 10) 10. The method of any one of claims 6 to 9, wherein the adhesive is one of a two-part epoxy, a one-part epoxy, or an acrylic adhesive. (Embodiment 11) 11. The method of claim 10, wherein the adhesive is cured by heat and / or ultraviolet light. (Embodiment 12) 1. A method for producing an insulating material, comprising the steps of: providing an inner wall configured to at least partially define a heating zone for receiving at least a portion of an article including smokable material, the inner wall containing a heating material that is heatable by the penetration of a varying magnetic field; providing an outer wall surrounding said inner wall at least partially along its length, an insulating region being formed between said inner wall and said outer wall; Providing one or more joining members; bonding each of the one or more bonding members to the inner wall; evacuating the insulating region to a pressure below atmospheric pressure; closing the insulation region by bonding at least one of the one or more bonding members to the exterior wall; A method comprising: (Embodiment 13) 13. The method of embodiment 12, wherein the inner wall and the outer wall comprise different materials. (Embodiment 14) 14. The method of claim 12 or 13, wherein the exterior wall and the one or more joining members comprise similar materials. (Embodiment 15) 15. The method of any one of claims 12-14, wherein the one or more joining members are end caps. (Embodiment 16) 16. The method of any one of claims 12-15, wherein the one or more joining members are joined to at least one of the inner wall and the outer wall using brazing, welding, soldering, adhesives, or an interference fit. (Embodiment 17) 17. The method of embodiment 16, wherein the brazing is performed using a silver eutectic braze material. (Embodiment 18) 18. The method of claim 16 or 17, wherein the adhesive used is one of a two-part epoxy, a one-part epoxy, or an acrylic adhesive. (Embodiment 19) 19. The method of claim 18, wherein the adhesive is cured by heat and / or ultraviolet light. (Embodiment 20) 20. The method of any one of embodiments 12-19, wherein when the insulating region is evacuated to a pressure below atmospheric pressure, a region outside the insulating region is also evacuated to a pressure below atmospheric pressure. (Embodiment 21) The pressure below atmospheric pressure is 10 -1 21. The method of any one of the preceding claims, wherein the pressure is below 1 Torr. (Embodiment 22) 22. The method of any one of the preceding claims, wherein the inner wall comprises mild steel or ferritic stainless steel. (Embodiment 23) 23. The method of any one of the preceding claims, wherein the outer wall comprises one or more of a non-sensitive metal, plastic, glass, or ceramic. (Embodiment 24) 24. The method of embodiment 23, wherein the non-sensitive metal is stainless steel. (Embodiment 25) An insulating material manufactured according to any one of embodiments 1 to 24. (Embodiment 26) An insulating material according to embodiment 25; a magnetic field generator for generating a varying magnetic field which, in use, penetrates the inner wall to heat the inner wall; A non-combustion aerosol delivery device comprising: (Embodiment 27) An apparatus as defined in embodiment 26, an aerosol-generating material that, in use, is at least partially disposed within the heated zone of the inner wall of the insulation; A non-combustion aerosol delivery system comprising:

Claims

1. 1. A method for producing an insulating material, comprising the steps of: providing an inner wall configured to at least partially define a heating zone for receiving an aerosol-generating material, the inner wall including a heating material that is heatable by the penetration of a varying magnetic field; providing an outer wall surrounding the inner wall at least partially along a length thereof, an insulating region being formed between the inner wall and the outer wall, the inner wall and the outer wall comprising distinct materials; depositing a portion of a first bonding material on the inner wall at atmospheric pressure; applying a portion of a second bonding material to the exterior wall at atmospheric pressure; evacuating the insulating region to a pressure below atmospheric pressure; closing the insulating region by bonding the first bonding material and the second bonding material together; A method comprising:

2. 2. The method of claim 1, wherein when the insulating region is evacuated to a pressure below atmospheric pressure, a region outside the insulating region is also evacuated to a pressure below atmospheric pressure.

3. The method of claim 1 or 2, wherein the portion of the first joining material and the portion of the second joining material are attached to at least one of the inner wall and the outer wall by brazing, welding, or soldering.

4. The method of any one of claims 1 to 3, wherein the first joining material and the second joining material are joined to each other by brazing, welding or soldering.

5. The method of any one of claims 1 to 4, wherein the first joining material and the second joining material comprise a silver eutectic braze material.

6. 1. A method for producing an insulating material, comprising the steps of: providing an inner wall configured to at least partially define a heating zone for receiving at least a portion of an article including smokable material, the inner wall containing a heating material that is heatable by the penetration of a varying magnetic field; providing an outer wall surrounding said inner wall at least partially along its length, an insulating region being formed between said inner wall and said outer wall; evacuating the insulating region to a pressure below atmospheric pressure; closing the insulating region by bonding the inner wall and the outer wall using an adhesive; A method comprising:

7. The method of claim 6 , wherein the inner wall and the outer wall comprise different materials.

8. 8. The method of claim 6 or 7, wherein when the insulating region is evacuated to a pressure below atmospheric pressure, a region outside the insulating region is also evacuated to a pressure below atmospheric pressure.

9. 1. A method for producing an insulating material, comprising the steps of: providing an inner wall configured to at least partially define a heating zone for receiving at least a portion of an article including smokable material, the inner wall containing a heating material that is heatable by the penetration of a varying magnetic field; providing an outer wall surrounding said inner wall at least partially along its length, an insulating region being formed between said inner wall and said outer wall; Providing one or more joining members; bonding each of the one or more bonding members to the inner wall; evacuating the insulating region to a pressure below atmospheric pressure; closing the insulation region by bonding at least one of the one or more bonding members to the exterior wall; A method comprising:

10. The method of claim 9 , wherein the inner wall and the outer wall comprise different materials.

11. The method of claim 9 or 10, wherein the exterior wall and the one or more joining members comprise the same material.

12. The method according to any one of claims 9 to 11, wherein the one or more joining members are end caps.

13. The method according to any one of claims 9 to 12, wherein the one or more joining members are joined to at least one of the inner wall and the outer wall by means of brazing, welding, soldering, adhesives, or an interference fit.

14. The method of claim 13, wherein the brazing is performed using a silver eutectic braze material.

15. 15. The method according to claim 13 or 14, wherein the adhesive used is one of a two-part epoxy, a one-part epoxy, or an acrylic adhesive.

16. The method of claim 15, wherein the adhesive is cured by heat and / or ultraviolet light.

17. A method according to any one of claims 9 to 16, wherein when the insulating region is evacuated to a pressure below atmospheric pressure, the region outside the insulating region is also evacuated to a pressure below atmospheric pressure.

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