Thermoformable shape memory and its use

Abstract

The present invention relates to a device comprising a first layer (11) of thermoformable material that is inelastically deformable in a thermoforming temperature range and a second layer (1) of viscoelastic material that is elastically deformable in a temperature range that includes a use temperature range of the device and a thermoforming temperature range, the use temperature range being lower than the thermoforming temperature range, the first layer being bonded to the second layer, the thermoformable material being elastically deformable and harder than the viscoelastic material in the use temperature range, and the thermoformable material being less hard than the viscoelastic material in the thermoforming temperature range.

Description

Technical Field

[0001] The present invention relates to a device having an initial shape that can undergo a permanent change when exposed to a specific temperature range and can recover its initial shape when exposed to this temperature without restraint. Specifically, the present invention applies to devices applied to the body of humans and / or animals, such as insoles, slippers, shoes, sprints, corsets, cervical collars, handles and grips present in sports or hand tools, saddles, seats, backs, backpacks, protective gear (chest protectors, helmets, shoulder protectors, elbow protectors, knee protectors, back protectors, protective vests...).

Background Art

[0002] Each individual has a unique morphology. Therefore, the interface between the individual's body and an object can be fully optimized for a specific use only if the interface conforms to the shape of the body it contacts.

[0003] Flexible and / or stretchable fabrics provide an optimal fit to the body surface using suitable patterns. Nevertheless, for some applications of health, clothing, protection, or comfort, it is necessary to contact the body surface with more or less hard objects for mechanical reasons. The objects related to these applications cannot, therefore, be made only of fabric or equivalents. For example, a device for supporting a joint must provide sufficient mechanical resistance to perform its support function while having at least two contact areas on the body on both sides of the joint. As another example, a device used for protecting a region of the body must provide hardness characteristics and sufficient thickness while conforming to the body surface.

[0004] Devices for these applications are still primarily mass-produced and therefore only available in a limited number of sizes to accommodate different shapes and dimensions, rarely exceeding 10 sizes for a single device. The category of mass-produced devices has the advantage of being relatively simple and inexpensive to manufacture, which explains their common nature. While most of these devices attempt to replicate the general shape of the body surface they will come into contact with, they never perfectly conform to the body of their user.

[0005] Another category of devices for these applications is custom-made, meaning they are manufactured in the presence of the end user according to their body surface, which allows for a much more precise match between the device's shape and the user's morphology. Nevertheless, these custom-made products are generally more complex and expensive to manufacture, hindering the savings that come with mass production. In addition, the process of measuring the user's body requires a time investment by the user before manufacturing can begin. Even though new digital technologies such as 3D printing and 3D imaging tend to mitigate the impact of these concerns by automating the production of unique digital models based on 3D anatomical data collected in digital files that can be generated by the user themselves, custom-made devices will still only fit the body for which they were specifically designed and therefore not suitable for other users. Devices in this category are therefore only usable as long as the user needs them and do not contribute to reducing waste and the consumption of Earth's resources.

[0006] A small number of other categories of devices for these same applications are based on the use of solid-formable materials, i.e., materials that can change shape when heated (thermoformable), or materials that can take on a solid form from a liquid or powder form. Thermoformable solid materials are typically supplied in sheet form, either made from a single material or compounded with other materials sensitive to the same temperature range. By applying a specific temperature, the sheet can be deformed by applying it to an intended area of ​​the body. This thermoforming operation is usually performed by a professional, or in some applications by the user themselves. Liquid or powder materials typically require the addition of at least one other component that triggers a chemical reaction that causes the material to solidify. During the chemical reaction, the material can be shaped to fit the target area of ​​the body. These two techniques provide a unique device that perfectly conforms to the shape of the user's body area, from mass-produced materials. Nevertheless, the realization of this type of device, while relatively fast, can be cumbersome, and professional intervention is often required to minimize the risk of error. Furthermore, devices manufactured in this manner are generally not reversible; that is, it is impossible to return the device to its original shape, correct molding errors, or reuse the device for another user. These devices, therefore, in addition to being difficult to implement given the molding steps with no tolerance for errors, have the same defects as custom-made devices.

[0007] Existing devices that have interfaces that come into contact with areas of the user's body are therefore either imperfectly adapted to this area or are user-specific, in addition to being complex to implement.

[0008] In recent years, thermoformable shape memory composite materials have been developed. These polymer-based materials can be easily molded within a specific temperature range and, in the absence of mechanical stress, may have the ability to return to their original shape even within this temperature range. For this purpose, these materials incorporate two types of fibers: fibers with a glass transition temperature within the desired thermoforming temperature range, and fibers with a glass transition temperature significantly higher than the desired thermoforming temperature range. Thus, thermoformable shape memory materials allow objects to be molded to the morphology of a user's body while also being able to return to their original shape. Some manufacturers propose this type of material for the mass production of objects by plastic injection molding. However, commercially available materials of this type cover a limited range of mechanical properties and are significantly more expensive than most materials used in plastic injection molding. In fact, these materials are either not stiff enough to support the joints of the human body, or they are too expensive, or their thermoforming temperatures are too high to be molded by applying the material to the body without the risk of burns to the user. By employing mechanical measures to stiffen the object through its shape (specifically by utilizing the second moment), the minimum flexural modulus that provides sufficient support can be estimated to be 1–2 GPa, depending on the size and force applied to the supported joint or body part.

[0009] Viscoelastic materials are also known to be applied to areas of the user's body to absorb impact and / or distribute pressure. However, viscoelastic materials generally cannot be molded at temperatures below 100°C and are not rigid enough to support joints or body parts.

[0010] Therefore, it may be desirable to provide a device having an interface that can reversibly conform to the shape of a human or animal body area and can be manufactured in a continuous manner. In relation to applications that come into contact with a human or animal body area, it may also be desirable for the device to have shock absorption and pressure distribution properties. [Overview of the Initiative]

[0011] Embodiments relate to a method for manufacturing a thermoformable shape memory device, the method comprising: forming a first layer of thermoformable material that is inelastically deformable over a thermoforming temperature range; forming a second layer of viscoelastic material that is elastically deformable over a temperature range including the thermoforming temperature range and a usage temperature range lower than the thermoforming temperature range, wherein the thermoformable material is elastically deformable over the usage temperature range and is harder than the viscoelastic material; and joining the first layer to the second layer by chemical or mechanical bonds distributed over the contact surface between the first and second layers, wherein the device has a usage shape defined by the first layer over the usage temperature range and an original shape defined by the second layer that provides the device a shape memory function over the thermoforming temperature range.

[0012] According to the embodiment, the first layer and the second layer are manufactured separately by molding or 3D printing and then assembled together, or the first layer is manufactured by molding or 3D printing and then placed in a mold for manufacturing the second layer, and the second layer is formed by molding using the mold including the first layer, or the first layer is manufactured by molding or 3D printing and forms a mold for manufacturing the second layer by molding.

[0013] According to one embodiment, the method includes the steps of heating the apparatus to a temperature within a thermoforming temperature range so that the apparatus returns to its original shape determined by the second layer by transferring the original shape of the second layer to the first layer via a contact surface, and bringing the apparatus to a temperature within a usable temperature range in which the apparatus is elastically deformable.

[0014] According to the embodiment, the method includes the steps of: heating the apparatus to a first temperature within the thermoforming temperature range, deforming the apparatus at the first temperature to make it conform to a shape different from its original shape; and raising the apparatus to a second temperature within the operating temperature range while maintaining the deformation, wherein the apparatus at the second temperature is elastically deformable to a shape different from its original shape.

[0015] Embodiments may also relate to an apparatus comprising a first layer of thermoformable material that is inelastically deformable within a thermoforming temperature range, and a second layer of viscoelastic material that is elastically deformable within a temperature range including the operating temperature range of the apparatus and the thermoforming temperature range, wherein the operating temperature range is lower than the thermoforming temperature range, the first layer is bonded to the second layer by chemical or mechanical bonds distributed across the contact surface between the first and second layers, the thermoformable material is elastically deformable and harder than the viscoelastic material within the operating temperature range, the thermoformable material is not harder than the viscoelastic material within the thermoforming temperature range, the first layer defines the operating shape of the apparatus within the operating temperature range, the second layer defines the original shape of the apparatus, and the apparatus achieves a shape memory function within the thermoforming temperature range.

[0016] According to the embodiment, the first layer is bonded to the second layer by one or a combination of the following: a chemical bond created by the fusion of the materials forming the first and second layers on both sides of the contact surface between the first and second layers; a layer of adhesive or a double-sided adhesive film that can chemically bond to the first and second layers; a mechanical bond based on a bonding profile distributed across the contact surface; and a seam.

[0017] According to one embodiment, the first layer is embedded in the second layer and / or the first layer includes a stud that enters a hole of a suitable shape in the second layer and / or the second layer includes a stud that enters a hole of a suitable shape in the first layer.

[0018] According to the embodiment, the first layer is PCL, PETG, EVA, PE, PU, ​​or PLA, or a thermoformable resin having a glass transition temperature of less than 100°C and / or having a rigidity of 1 to 2 GPa.

[0019] According to the embodiment, the second layer has at least one of the following characteristics: being SEBS, or silicone, or silicone gel, or PU, EVA, or PE foam, and having a Shore A hardness of 1 to 30.

[0020] According to an embodiment, the second layer has the shape of an insole configured to cover the heel and the sole of the foot, and the first layer extends from the heel to the bottom of the midfoot bone.

[0021] According to an embodiment, the second layer extends to the tip of the toe.

[0022] According to an embodiment, the first layer and the second layer form a handle or grip intended to be held by hand.

[0023] According to an embodiment, the second layer is cylindrical, and the first layer is tubular and covers the second layer, or the second layer is tubular, and the first layer includes a tubular inner portion covering the inner surface of the second layer and a tubular outer portion covering the outer surface of the second layer, or the second layer is tubular, and the first layer includes a tubular inner portion covering the inner surface of the second layer, and the second layer is intended to contact the hand.

[0024] Non-limiting examples of embodiments of the present invention will be described below in connection with the accompanying drawings. [[ID={17}]]

Brief Description of the Drawings

[0025] [Figure 1A-B] FIG. 1A is a schematic top view and FIG. 1A is a schematic cross-sectional view taken along cross-section AA shown in FIG. 1A of a composite material pad according to an embodiment. [Figure 2A-B] FIG. 2A is a schematic top view and FIG. 2A is a schematic cross-sectional view taken along cross-section BB shown in FIG. 2A of a composite material pad according to another embodiment. [Figure 3A-B] FIG. 3A is a schematic top view and FIG. 3A is a schematic cross-sectional view taken along cross-section CC shown in FIG. 3A of a composite material pad according to another embodiment. [[ID={32}]] [Figure 4] FIG. 3 is a schematic cross-sectional view of a composite pad according to another embodiment. [Figure 5] FIG. 4 is a perspective view of a part of a handle made of a composite material according to an embodiment. [Figure 6] FIG. 5 is a perspective view of a part of a handle made of a composite material according to another embodiment. [Figure 7]It is a perspective view of the composite material insole according to the embodiment.

Best Mode for Carrying Out the Invention

[0026] Figures 1A and 1B show a pad 10 made of a composite material according to an embodiment. The pad 10 includes a layer 1 of viscoelastic material in which a layer 11 of thermoformable material is embedded. The layer 1 is elastically deformable within a temperature range including the use temperature range of the pad 1 and the thermoforming temperature range of the layer 11 above the glass transition temperature at which the layer 11 can be inelastically deformed, and the use temperature range is lower than the thermoforming temperature range. Further, within the use temperature range, the material of the thermoformable layer 11 is harder than the viscoelastic material of the layer 1, and within the thermoforming temperature range, the material of the thermoformable layer 11 is not harder than the viscoelastic material of the layer 1.

[0027] Therefore, within the use temperature range, the shape of the pad 10 is given by the shape of the thermoformable layer 11 that is harder than the viscoelastic layer 1. Due to the presence of the thermoformable layer 11, the pad 10 can be inelastically deformed after being heated to a temperature within the thermoforming temperature range, whereby the layer 1 collapses and / or elastically deforms. If this deformation is maintained while the pad 10 cools to the temperature of the use temperature range, the layer 11 maintains its shape, becomes harder, and constrains the layer 1. The layer 11 thus determines the shape of the pad 10. When the pad 10 is heated to the temperature of the thermoforming range without applying stress to its surface, the harder elastically deformed layer 1 urges the layer 11 to return to its original shape, and that shape is maintained when the pad returns to the temperature of the use temperature range. As a result, the composite material made of the layers 1 and 11 has both thermoformability and shape memory.

[0028] In contrast, most thermoformable materials do not have shape memory, and thus it can be observed that, without an external force, the layer of thermoformable material does not naturally return to its initial shape at the thermoforming temperature.

[0029] In the example shown in Figures 1A and 1B, layer 11 has through-holes 22 distributed across its surface, filled with the material of layer 1, and providing a mechanical bond between layer 1 and layer 11 throughout the entire contact area between layers 1 and 11.

[0030] According to the embodiment, the thermoforming temperature range is such that layer 11 can be deformed by hand without the risk of burns. The thermoforming temperature range can therefore be 50 to 100°C. For example, the glass transition temperature of layer 11 is 50 to 80°C, and the glass transition temperature of layer 1 (the upper limit of the elastic deformation temperature range of layer 1) is higher than the thermoforming temperature range, for example, above 110°C.

[0031] Figures 2A and 2B show a pad 20 made of a thermoformable shape memory composite material according to another embodiment. The pad 20 includes a layer 2 made of the same viscoelastic material as layer 1, and a layer 12 made of the same thermoformable material as layer 11. The pad 20 differs from the pad 10 in that layer 12 is located on the surface of layer 2.

[0032] Layers 2 and 12 are chemically bonded together. This chemical bond between the two materials is achieved, for example, by mixing the materials of layers 2 and 12 over a small thickness on both sides of the interface between the two layers. This chemical bond can also be achieved by bringing the two layers 2 and 12 into contact while parts of each layer are still in a liquid state, before they are completely cured.

[0033] In the embodiments shown in Figures 1A and 1B, it should be noted that the two layers 1 and 11 can also be chemically bonded, for example, by mixing the materials of layers 1 and 11 over a small thickness on both sides of the interface between these two layers. In this case, the pores 21 may be omitted.

[0034] According to another embodiment, layers 2, 12 are joined to each other by seams and / or by another layer of material which can be manufactured separately and bonded to both layers 2, 12. Examples of this other material include adhesives and / or double-sided adhesive films or fabrics.

[0035] In the example shown in Figures 2A and 2B, layer 12 also has holes 22, which may be blind holes that open toward layer 2 and are filled with the material forming layer 2. The holes 22 increase the contact surface between the two layers 2 and 12, and thus increase their bonding.

[0036] Figures 3A and 3B show a pad 30 made of a thermoformable shape memory composite material according to another embodiment. The pad 30 includes a layer 3 made of the same viscoelastic material as layer 1, and a layer 13 made of the same thermoformable material as layer 11. The pad 30 differs from the pad 20 in that layer 13 is mechanically bonded to layer 3. For this purpose, layer 13 may be a blind hole and has a hole 23 that opens toward layer 3 with a narrower cross-section than another portion of the hole, and the hole 23 is filled with the material forming layer 3.

[0037] Figure 4 shows a pad 40 made of a thermoformable shape memory composite material according to another embodiment. The pad 40 includes a layer 4 made of the same viscoelastic material as layer 1, and a layer 14 made of the same thermoformable material as layer 11. The pad 40 differs from the pad 30 in that layer 14 is mechanically bonded to layer 4 by studs 24 formed in layer 14 and penetrating into layer 4 from the contact surface between layer 14 and layer 4. Layer 4 may be blind holes and include holes formed opposite the studs 24, with a shape complementary to the studs 24. Each stud may have a base narrower than the other cross-section of the stud, providing a strong bond between layers 4, 14. Thus, the two layers 4, 14 may be fabricated separately and then joined together by applying relatively strong pressure to push the studs 24 of layer 14 into the opposing holes formed in layer 4. Alternatively, layer 4 may be molded on layer 14.

[0038] In the examples shown in Figures 1A, 2A, 3A, and 4, the volumes of connectors 21, 22, 23, and 24 have a circular cross-section. This cross-section may be of other shapes, including groove cross-sections, that can accommodate the desired bonding force between the two layers, and the bonding force is related to the stress that the pad can withstand, specifically torsional stress.

[0039] Figures 5 and 6 show a portion of a cylindrical handle. In Figure 5, the handle portion 50 includes a cylindrical viscoelastic layer 5 covered with a tubular thermoformable layer 15 surrounding layer 5. Layer 5 may be formed from the same material as layer 1, and layer 15 may be formed from the same material as layer 11. The two layers are mechanically bonded together by layer 5 housed in layer 15. If it is desirable that the contact area between the two layers 5 and 15 not be altered as a result of the thermoforming operation of the thermoformable layer, the two layers may be chemically bonded together over the entire contact area using one of the above methods, with or without using another material such as a double-sided adhesive film.

[0040] Therefore, when the sleeve portion 50 is heated to a temperature within the thermoforming temperature range, the layer 15 can be deformed by hand, and that deformation can be transmitted to the layer 5. As the sleeve portion 50 cools while maintaining its deformation, the deformation is maintained until the sleeve portion is heated again to the thermoforming temperature and left without applying mechanical stress, allowing the elastically deformed layer 5 to return to its original shape.

[0041] In Figure 6, the shown sleeve portion 60 is hollow. Therefore, the viscoelastic layer 6 is tubular and has an inner surface and an outer surface, and has, for example, a cylindrical cross-section. The outer surface of layer 6 is tubular in shape and is covered with an outer thermoformable layer 16a that conforms to the shape of the outer surface of layer 6. The inner tubular layer 16b is inserted into layer 6 and is shaped to contact the entire inner surface of layer 6. The inner layer 16b may or may not be thermoformable, depending on the intended application.

[0042] To improve the bonding between layer 6 and layer 16b, a bonding profile can be formed at the interface between these two layers. In the example shown in Figure 6, this bonding profile includes axial grooves formed in layer 16b and distributed across the cylindrical surface of layer 16b at the interface with layer 6, the grooves cooperating with a conforming rib 26 formed in layer 16b. In the example shown in Figure 6, the rib 26 has a dovetail cross-section. Its tubular shape allows the handle portion 60 to be inserted into a handle, such as a racket handle, or a grip, such as a hand tool handle. Because it is thermoformable, the handle portion 60 can be shaped to conform to the shape of the part of the user's hand that contacts the handle.

[0043] In another embodiment, grooves are formed in layer 6 and ribs 26 are formed in layer 16b.

[0044] In the embodiments of Figures 5 and 6, the handle or grip may be covered with a coating that may be suitable for contact with the hand, such as a viscoelastic material. Alternatively, in the embodiment of Figure 6, layer 16a may be omitted, and as a result, the outer surface of the viscoelastic layer 6 will be in direct contact with the hand.

[0045] Figure 7 shows an insole 70 comprising a viscoelastic layer 7 made of the same viscoelastic material as layer 1, and a thermoformable layer 17 made of the same viscoelastic material as layer 11, the two layers being mechanically or chemically bonded to each other according to one and / or other of the various embodiments described above. In the example of Figure 7, the assembly configuration of layers 7 and 17 corresponds to that described in relation to Figures 3A, 3B, with orifices 27 distributed in layer 17 (the upper part of the insole shown in Figure 7), and each of the orifices 27 having an undercut profile on the axial plane (relative to the orifice). Layer 17 also includes an opening 37 encompassing a heel support zone, and as a result, in this zone where the pressure applied by the foot may be greatest, the insole has a reduced stiffness corresponding only to the stiffness of the viscoelastic layer 7, which is not stiffer than layer 17.

[0046] According to other embodiments, layers 7 and 17 are manufactured separately and bonded together by chemical and / or mechanical bonding. Depending on the application, either layer 7 or layer 17 may be positioned to come into contact with the sole of the foot.

[0047] In another embodiment, layer 17 extends from the heel to the toe.

[0048] During the thermoforming operation of the insole 70 at the thermoforming temperature, the insole is pressed against the user's foot and held in that position until the temperature of the insole returns to the usable temperature range.

[0049] The presence of viscoelastic layers 1-7 in the device advantageously provides shock absorption and load distribution functions. For this purpose, the viscoelastic layers may have a Shore A hardness of 1-30, e.g., 4-20, and a tensile strength of 1.5-5 MPa in the operating temperature range and thermoforming temperature range. In applications to insoles, viscoelastic layer 7 has a Shore A hardness of 15-20, e.g., 16.

[0050] According to various embodiments, the viscoelastic layers 1-7 may be low-hardness SEBS (styrene-ethylene-butylene-styrene) having a glass transition temperature of about 120°C, or PDMS (polydimethylsiloxane), which is a silicone or silicone gel having a glass transition temperature of about 220°C. The viscoelastic layers 1-7 may also be PU (polyurethane) foam, EVA (ethylene vinyl acetate), or PE (polyethylene).

[0051] According to various embodiments, the thermoformable layers 11-16a, 16b, and 17 may be made of any of the following materials: PCL (polycaprolactone) has a glass transition temperature of approximately 50°C. PLA (polylactic acid polyester) has a glass transition temperature of approximately 60°C. PETG (polyethylene terephthalate glycol) has a glass transition temperature of approximately 80°C. • EVA having a glass transition temperature of approximately 85°C PU or PE having a glass transition temperature of less than 100°C - Or a thermoformable resin having a glass transition temperature of less than 100°C.

[0052] According to various embodiments, layers 11-16a, 16b, and 17 may have a thickness of 0.5-3 mm and / or a stiffness (or Young's modulus) of 1-2 GPa.

[0053] According to various embodiments, the manufacture of the apparatus (pads 10, 20, 30, 40, handles 50, 60, insoles 70) may include the following steps: Thermoformable layers 11-17 are manufactured by molding (injection, casting, extrusion, etc.) or additive manufacturing (3D printing). The resulting layers 11-17 are placed in a mold of the desired shape for viscoelastic layers 1-7, in which viscoelastic layers are molded (by casting, injection, etc.), and the molds are filled with viscoelastic material in liquid form to form viscoelastic layers 1-7. In the case of handle 50, thermoformable layer 15 forms a mold for forming viscoelastic layer 5. In the case of handle 60, layers 16a, 16b, which are pre-held in their final configuration, form a mold used to cast viscoelastic layer 6.

[0054] According to another embodiment, the viscoelastic layers 1-7 and the thermoformable layers 11-15, 17 or thermoformable layers 16a, 16b are manufactured separately by molding or additive manufacturing (such as casting, injection molding, or extrusion), and then assembled by bonding with adhesives or by mechanical connections such as complementary undercut shapes (Figure 4) that take advantage of the elastic deformability of the viscoelastic layers.

[0055] It will be apparent to those skilled in the art that the present invention has various substitutions and applications. Specifically, the present invention is not limited to applications applied to areas of the human or animal body, but can be used in applications requiring a thermoformable shape-memory viscoelastic material having the properties described above.

[0056] Furthermore, some of the bonding modes between the thermoformable layer and the viscoelastic layer may be combined. Thus, the thermoformable layer may be bonded to the viscoelastic layer by both chemical and mechanical bonding modes. The holes or studs created in the thermoformable layer are not necessarily all the same shape and size. In addition, the thermoformable layer may have both holes and studs, each of which works in cooperation with complementary shapes created in the viscoelastic layer.

Claims

1. A method for manufacturing a thermoformable shape memory device, wherein the apparatus is thermoformable to have a usable shape that conforms to a desired shape within the operating temperature range. The aforementioned method, The steps include forming a first layer of a thermoformable material that is inelastically deformable within a thermoforming temperature range and is not a shape memory material, The steps include forming a second layer of viscoelastic material that is elastically deformable in a temperature range that includes the thermoforming temperature range and the operating temperature range lower than the thermoforming temperature range, The steps include: joining the first layer to the second layer by chemical or mechanical bonds distributed across the contact surface between the first layer and the second layer; Includes, The thermoformable material is elastically deformable within the operating temperature range and is harder than the viscoelastic material. The first layer defines the usage shape of the device within the operating temperature range. The second layer defines the original shape of the apparatus and provides a shape memory function within the thermoforming temperature range. The method wherein the thermoforming temperature range is 50°C to 100°C.

2. The first layer and the second layer are manufactured separately by molding or 3D printing, and then assembled together, or The first layer is manufactured by molding or 3D printing and then placed in a mold for manufacturing the second layer, and the second layer is formed by molding using the mold containing the first layer, or The first layer is manufactured by molding or 3D printing, and forms a mold for the molding of the second layer. The method according to claim 1.

3. The steps include heating the apparatus to a temperature within the thermoforming temperature range so that the apparatus returns to the original shape determined by the second layer by transferring the original shape of the second layer to the first layer via the contact surface, The steps include: bringing the device to a temperature within the operating temperature range in which the device can be elastically deformed; The method according to claim 1, including the method described in claim 1.

4. The steps include: heating the apparatus to a first temperature within the thermoforming temperature range, and deforming the apparatus at the first temperature to make it conform to a working shape different from the original shape; A step of raising the device to a second temperature within the operating temperature range while maintaining the deformation, wherein the device at the second temperature is elastically deformable to the operating shape which is different from the original shape. The method according to claim 1, including the method described in claim 1.

5. A thermoformable shape memory device, which is thermoformable to have a shape suitable for a desired shape within an operating temperature range, and the device is A first layer of a thermoformable material that is inelastically deformable within the thermoforming temperature range and is not a shape memory material, A second layer of viscoelastic material that is elastically deformable within a temperature range including the operating temperature range and the thermoforming temperature range of the apparatus, Includes, The aforementioned operating temperature range is lower than the aforementioned thermoforming temperature range, which is 50°C to 100°C. The first layer is bonded to the second layer by chemical or mechanical bonds distributed across the contact surface between the first layer and the second layer. The thermoformable material is elastically deformable within the operating temperature range and is harder than the viscoelastic material. The thermoformable material is not harder than the viscoelastic material within the thermoforming temperature range. The first layer defines the usage shape of the device within the operating temperature range. The second layer defines the original shape of the apparatus and achieves the shape memory function of the apparatus within the thermoforming temperature range. Device.

6. The first layer is as follows: Chemical bonds formed by the fusion of the materials forming the first and second layers on both sides of the contact surface between the first and second layers, A layer of adhesive or a double-sided adhesive film that can chemically bond to the first layer and the second layer, Mechanical connection based on a bonding profile distributed across the contact surface, and seam, The apparatus according to claim 5, wherein the second layer is bonded by one or a combination of the following.

7. The first layer is embedded in the second layer and / or The first layer includes a stud that enters a hole of a suitable shape in the second layer, and / or The second layer includes studs that enter into holes of a suitable shape in the first layer. The apparatus according to claim 5.

8. The first layer is, PCL, PETG, EVA, PE, PU, ​​or PLA, or a thermoformable resin having a glass transition temperature of less than 100°C, and / or Having a rigidity of 1 to 2 GPa, The apparatus according to claim 5.

9. The second layer described above has the following characteristics: It must be SEBS, or silicone, or silicone gel, or PU, EVA, or PE foam. It must have a Shore A hardness of 1 to 30. The apparatus according to claim 5, having at least one of the following.

10. The apparatus according to claim 5, wherein the second layer has the shape of an insole configured to cover the heel and sole of the foot, and the first layer extends from the heel to the base of the metatarsal head.

11. The apparatus according to claim 10, wherein the second layer extends to the tip of the toe.

12. The apparatus according to claim 5, wherein the first layer and the second layer form a handle or grip intended to be held by hand.

13. The second layer is cylindrical, and the first layer is tubular, covering the second layer, or The second layer is tubular, and the first layer includes a tubular inner portion covering the inner surface of the second layer, and a tubular outer portion covering the outer surface of the second layer, or The second layer is tubular, and the first layer includes a tubular inner portion covering the inner surface of the second layer, and the second layer is intended to come into contact with the hand. The apparatus according to claim 12.

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