Novel foam products

Abstract

This invention is inspired by the skeletal structure of animals, which is typically hollow. It introduces a novel foam article and its manufacturing method, comprising cavities resembling a bone structure. The novel foam article includes a cavity-defined structure placed within a mold before expanded polymer microspheres are placed inside. The cavity-defined structure comprises cavities or cavity layers, forming large cavities and hollow compartments at specific dimensions and locations within the foam article during molding. Therefore, compared to conventionally manufactured foam articles, foam articles employing a cavity-defined structure use fewer polymer microspheres and are lighter. This invention also improves the shock absorption, durability, thermal insulation, sound insulation, and buoyancy of the foam article.

Description

Background Technology

[0001] Foamed plastics are widely used in many fields, such as cushioning, comfort, thermal insulation, sound insulation, buoyancy, and building construction. The manufacturing of foamed plastic products largely focuses on producing foams with a single density; in many cases, the foam is not adequately optimized for specific applications. This results in relatively heavy foams that are not optimized for particular applications in terms of strength, density, durability, insulation, and shock absorption.

[0002] Customizing foam products by uniformly altering the density and porosity at the microscopic level does not necessarily yield optimal results for a specific application. For example, cured and aged expanded polystyrene (EPS) beads are approximately 95% air and only 5% plastic. However, EPS foam made from beads may not fully realize its strength, shock absorption, buoyancy, durability, and volumetric insulation properties. With the widespread use of foam products, improving foam properties and reducing its weight are preferable in many applications.

[0003] In almost all applications of foam products, maximum performance and minimum weight are desirable, and using existing forms of single-density foam may not yield optimal results. Single-density foam is primarily used in applications such as thermal and acoustic insulation (machinery, electrical appliances, and buildings), shock absorption (head protection, body protection, and vehicle bumpers), and transportation (vehicles and ships). In some designs, layers of foam with different densities are used to improve the shock absorption capacity of the foam product. Multi-density foams perform better than single-density foams, but they are more expensive and have design limitations. Single-density foam products are also primarily used in floating applications such as boats, buoys, and surfboards.

[0004] The mechanical properties of foamed plastics can vary depending on the production process and the type of polymer used. Generally, foamed plastics can be divided into two categories: single-impact and multi-impact plastics. Single-impact foamed plastics, such as EPS and EPA (expanded polylactic acid), do not return to their original shape after being deformed by impact; their structure is permanently damaged. On the other hand, multi-impact foamed plastics, such as foams made of polypropylene or polyethylene, can return to their original shape after deformation. Given the large quantities of foamed plastics used in various applications, any improvements that enhance foam properties and reduce the amount of foam used in specific applications are attractive to the industry. Summary of the Invention

[0005] This content is provided to introduce various concepts in a simplified form, which will be further described in the detailed description below. This content is not intended to explain the essential features of the subject matter of the claims, nor is it intended to be used as a tool for determining the scope of the claims. In one aspect, this disclosure describes a novel foam article and a method for manufacturing such a foam article.

[0006] Foam is mainly composed of very small cavities (micropores or microcavities), which are usually evenly distributed in its structure.

[0007] This invention is a result of observation and imitation of nature. In particular, its design is inspired by skeletal structure. While bones may appear solid to the naked eye, they comprise both micro-cavities and macro-cavities. Holes in skeletal structures typically exist as cavities within the bones themselves. This allows bones to utilize the advantages of both micro- and macro-cavities to achieve an optimal structure. By mimicking skeletal structure, this invention describes a foam article structure that simultaneously possesses micro- and macro-cavities. This invention also describes a molding method for foam articles that improves the performance of foam articles in specific applications by creating and designing larger cavities (macro-cavities) within any given foam article. Furthermore, this invention makes the use of foam plastics more sustainable by reducing the amount of expanded polymer microspheres used in foam articles.

[0008] The first aspect of the invention provides a method for manufacturing foam articles, wherein, when molding expanded polymer beads, a cavity-defining structure is provided to a mold to form macroscopic cavities in the foam article.

[0009] Structures defined as cavities may include objects with open cavities, objects with closed cavities, sheets, covering layers, mesh layers, perforated bodies, hollow bodies, solids, or combinations thereof.

[0010] The molding process can be carried out in two or more stages, and the use of a covering layer as a defining feature of foam products is a cavity structure.

[0011] When an object with an open cavity, an object with a closed cavity, or a hollow body is used as a structure defined as a cavity in a foam product, the molding process can be completed in one stage.

[0012] Molding using expanded polymer microspheres and a structure defined as cavities can be carried out in multiple molding processes, wherein a foam article with open cavities is produced in the first molding process, and in the second molding process, the foam article with open cavities is partially or completely covered by a structure defined as cavities, and then expanded polymer microspheres are introduced into the mold to form predetermined cavities in the foam article.

[0013] The molding of expanded polymer microspheres and the cavity-defined structure can be completed in a single molding process, wherein the cavity-defined structure is placed in the mold before the expanded polymer microspheres are introduced into the mold to form a predetermined cavity in the foam article according to the shape, position and configuration of the cavity-defined structure.

[0014] A second aspect of the invention provides a foam article comprising expandable polymer microspheres and cavities defined by structures within the expandable polymer microspheres that are defined as cavities, wherein the structures defined as cavities include objects having one of the following characteristics: open cavities, objects having closed cavities, sheets, covering layers, mesh layers, perforated bodies, hollow bodies, solid bodies, or combinations thereof.

[0015] Further aspects of preferred embodiments are provided in the dependent claims. Attached Figure Description

[0016] The above-described contents of this disclosure will become more readily understood with reference to the following detailed description and accompanying drawings, wherein:

[0017] Figure 1 A cross-section of a mold according to an embodiment of the present disclosure is shown, including a cavity compartment defined as a cavity structure placed within the mold when molding a foam article.

[0018] Figure 2 A cross-section of a helmet according to one embodiment of the present disclosure is shown, including a shock-absorbing liner of the helmet comprising a structure defined as a cavity.

[0019] Figure 3 A cross-section of a helmet portion according to an embodiment of the present disclosure is shown, including a structure defined as a cavity in the form of a cover layer.

[0020] Figure 4 A cross-section of a helmet portion according to an embodiment of the present disclosure is shown, including a covering layer that serves as a structure defined as a cavity and also as the outer shell of the helmet.

[0021] Figure 5 A cross-section of a helmet according to one embodiment of the present disclosure is shown, including a structure defined as a cavity, which takes the form of a layer covering the open cavity to create a macroscopic cavity. Detailed Implementation

[0022] The following detailed description, relating to the accompanying drawings, wherein the numbers refer to elements, is intended as a description of various embodiments of the claimed subject matter and does not represent the only embodiments. Each embodiment described in the invention is merely an example or illustration and should not be construed as excluding other embodiments. Any reference to a particular direction is made only to the drawings to further enhance clarity of explanation and not to limit the actual use of the invention in that direction. The illustrated examples are not intended to be exhaustive or to limit the invention to the precise forms shown.

[0023] In the next section, specific details will be explained to provide a full understanding of exemplary embodiments of the invention. It will be apparent to those skilled in the art that the illustrated embodiments can be implemented without showing every specific detail. Embodiments of the invention may also employ any combination of the features described below.

[0024] The following description provides an illustration of several novel foam products that include a structure defined as a cavity, which is placed within a mold when molding foam products using expanded polymer microbeads.

[0025] The disclosed content was invented by studying and imitating how structures are formed in nature, primarily inspired by skeletal structures. To the naked eye, bones may appear solid, but they contain microcavities; furthermore, bones can be hollowed out, creating macrocavities. This allows bones to possess an optimal structure by simultaneously utilizing the advantages of both micro and macro cavities. By mimicking skeletal structures, this invention describes a molding method for foam articles to improve the performance of foam articles in specific applications by creating and designing larger cavities within the foam.

[0026] In the context of this invention, a macroscopic cavity refers to a void that can be seen with the naked eye.

[0027] Please note that the terms "cavity" and "porosity" are used interchangeably in this disclosure and are assumed to have the same meaning.

[0028] As further described in this section, a cavity-defined structure allows for the presence of cavities and hollow spaces within foam products. A cavity-defined structure can be designed to accommodate the intended use of the foam product. A cavity-defined structure can reduce the number of expandable polymer beads used in foam products, enhance their shock absorption, improve their durability, strengthen the foam product structure, improve their thermal or acoustic insulation capabilities, and allow for the attachment of other accessories to the foam product.

[0029] Polymer foams are used in a variety of applications, such as shock absorption, thermal insulation, sound insulation, comfort padding, buoyancy, and construction. The porosity of foam helps absorb shocks, form insulation, provide comfort, reduce the weight of objects, float, and fill voids.

[0030] Calculations show that increasing the porosity of foam products can significantly improve their performance in all applications, such as better shock absorption, better insulation (including thermal and acoustic), better durability, and better buoyancy.

[0031] One of the common materials used to make buoys and other floating objects is expanded polystyrene (EPS). These buoys are typically in very harsh environments, subjected to impacts from ships, waves, and coastlines. Using a cavity structure in marine applications reduces the amount of polymer beads used in the foam product, increases its buoyancy, strengthens the foam structure used in the floating object, and improves the foam's durability. The cavity structure also provides connections for the foam product, allowing it to be securely attached to other objects such as boats, docks, or other parts of the vessel.

[0032] Traditional molding of foams such as expanded polystyrene (EPS) and its biodegradable expanded polylactic acid (EPA) relies primarily on the uniform micropores provided by the cured beads and the geometry of the foam product. In most cases, macropores or macrocavities are not considered in the foam structure. Such foam designs in the industry result in the consumption of more raw materials, relatively heavier foams, and unoptimized performance for specific applications. Although foams like EPS and EPA have a porosity of approximately 95% (a volume ratio of 20 air to 1 plastic), in almost all normal impact applications, such as helmets and packaging, foam products will not be compressed to 20 times their original thickness. Compression to two-thirds of its original thickness is considered good performance. During an impact, the low compressibility of the foam transfers more impact to the object / person it is meant to protect. One reason for the poor performance of foam is that the beads are tightly packed together, leaving no space for lateral expansion during vertical compression. Incorporating large pores or macrocavities into the foam can improve its compressibility, allowing it to be lighter yet perform better. Large pores create air gaps, which facilitate the collapse of the beads upon impact, allowing the foam to better reduce impact force. These giant air gaps also improve insulation (including acoustic and thermal applications) and buoyancy. Furthermore, the ability to control the porosity of foam products allows for the design of foams to specifications, optimizing their performance for specific applications.

[0033] This disclosure describes, in one aspect, a novel foam article and a molding method for creating foam articles with defined cavities that can reduce weight and strengthen the structure of the foam article, thereby improving its performance in a particular application. In one embodiment, macroscopic cavities are created by placing a structure within the mold before introducing expanded polymer microspheres into the mold. The macroscopic cavities are defined by a structure embedded in the mold that creates cavities in the desired areas.

[0034] Traditional foam articles may include open cavities. However, open cavities have limitations and can only be used under certain conditions. For example, the use of open cavities is common in packaging to reduce the amount of foam used. This concept is feasible because foam is often placed inside boxes as a final packaging layer. If the open cavity would be exposed in the final product, then open cavities are not very practical. In this disclosure, the final foam does not have open cavities or no clearly defined open cavities; the cavities are primarily formed within the final foam article using structures defined as cavities. This concept allows the foam to be used in a wide range of applications without existing limitations.

[0035] In one embodiment, the molding using expanded polymer microspheres and a structure defined as a cavity is completed in multiple molding processes. For example, in a first molding process, a foam article with cavities is formed using expanded polymer microspheres. Then, in a second molding process, the foam article with open cavities is placed in a mold and partially or completely covered by a structure defined as a cavity, and then expanded polymer microspheres are introduced into the mold to form predetermined cavities in the foam article. In this case, a layer is applied over the open cavities from the first step to define closed cavities. This layer can be a thin film, membrane, sheet, or mesh, and it can be compliant or rigid.

[0036] In one embodiment, the molding of expanded polymer microspheres and a structure defined as a cavity is completed in multiple molding processes. For example, in a first molding process, expanded polymer microspheres are used to form a foam article without cavities. Then, in a second molding process, the foam article without open cavities is placed in a mold, and the structure defined as a cavity is placed in the form or shape of an object with open cavities, such that the object, together with the foam article from the first molding process, forms a closed cavity. Expanded polymer microspheres are then introduced into the mold, allowing them to form around the closed cavity. In this case, during the second molding process, a rigid layer with open cavities is placed in the mold to define the closed cavity with the aid of the foam article from the first molding. This layer can be a sheet or a mesh.

[0037] Molded foam products have a wide range of applications, including protective helmets, vehicle safety features and components, aircraft, ships, construction, thermal insulation, sound insulation, flotation devices, comfort padding, and other applications. All conceivable applications of foam products can benefit from the cavity structures and the addition of macroscopic cavities defined herein.

[0038] In recent years, the use of foamed plastics, such as polystyrene foam, in construction has increased significantly. Polystyrene foam is used for thermal insulation (including heat and sound insulation) in buildings, as well as for filling gaps in the construction of bridges, roads, or buildings. By using structures defined as cavities in foam articles, it is possible to reduce the amount of foam used in construction by 15% to 30%. At the same time, the foam will have superior performance in terms of strength and insulation. It is well known that creating closed cavities can increase thermal resistance. The polymer beads used in EPS foam are already filled with microcavities, approximately 95% of which are voids and only 5% are plastic. This property makes EPS lightweight, an excellent insulation material, and also an excellent shock absorber. Structures defined as cavities provide macroscopic cavities in addition to the existing microcavities in the foam. These two types of cavities (i.e., macro and micro) are complementary and improve the performance of the foam in specific applications.

[0039] The following detailed description includes sketches, where numerical references to similar elements are intended as descriptions of various embodiments of the claimed subject matter, and not as representations of only one embodiment. Each embodiment defined for the invention is by way of example or illustration only and should not be construed as excluding the possibility of other embodiments. Any references to directions are used only for the purposes of the diagrams to enhance clarity of description, and not to limit the practical application of the invention in that direction. The examples shown are not intended to be exhaustive or to limit the invention to the precise form shown.

[0040] In the next section, specific details will be explained to provide a deeper understanding of exemplary embodiments of the invention. It will be apparent to those skilled in the art that the illustrated embodiments can be implemented without showing every specific detail. Embodiments of the invention may also employ any combination of the features described below.

[0041] The following description provides several examples illustrating methods for giving foam products defined macroscopic cavities by placing a structure defined as a cavity in a mold.

[0042] This disclosure defines a novel foam structure with macroscopic cavities and a method for molding foam articles including macroscopic cavities, which results in better foam performance than foam articles containing only microscopic cavities. In this respect, the cavity-defined structure allows the foam article to possess both microscopic and macroscopic cavities, thereby achieving better overall performance, such as lower weight, better strength, better shock absorption, better durability, and better insulation. This property is desirable in many applications of foam articles.

[0043] Molding foam products with macroscopic cavities can consume less raw materials, making the foam more cost-effective. The volume of each macroscopic cavity should ideally be greater than 0.3 cm. 3 Depending on the application, it is best to be larger than 3 cm. 3 .

[0044] In one embodiment, a macroscopically defined cavity is created by placing a structure defined as a cavity in the mold before filling the mold with a foam component (such as expanded polymer microspheres or other fluid or solid forms of foam component and combinations thereof).

[0045] In one embodiment, a cavity-defined structure in the mold creates one or more of the following: cavities, holes, channels, veins, or any other hollow spaces in the foam article, and the way the foam article is connected.

[0046] In one embodiment, a structure defined as a cavity creates an open or closed cavity.

[0047] In one embodiment, molding includes multiple molding stages, using the same or different molding tools.

[0048] In one embodiment, the structure defined as a cavity consists of one or more hollow compartments connected by solid or hollow connectors that link the hollow compartments together.

[0049] In one embodiment, the structure defined as a cavity includes a mesh-like structure consisting of hollow compartments and hollow or solid connectors or layers. In some locations, the structure defined as a cavity may include a connection method for attaching a foam article to another foam article or object. An example of this embodiment is embedding the mesh-like structure as a cavity within the foam, with a portion of the structure protruding from the outer surface of the foam article. The protruding portion of the structure defined as a cavity may include a connection method that securely attaches the foam article to another foam article or object using mechanical connections such as screws, locking mechanisms, pins, rivets, nails, straps, buckles, or ropes. Such applications of the foam article could include the installation of insulation panels, shock-absorbing components in vehicles, shock-absorbing components in head and body protection equipment (such as foldable helmets), flotation components, or any other conceivable application where foam functions similarly.

[0050] In one embodiment, the hollow space inside the foam article is created by a structure defined as a cavity to enhance the foam’s capabilities in terms of weight, strength, shock absorption, thermal insulation, sound insulation, buoyancy, and combinations thereof.

[0051] In one embodiment, the foam article includes macroscopic and microscopic cavities. Most foams, such as EPS and EPA, are made of expanded polymer microspheres, which are made of resin and expanded to more than 20 times their original volume. This expansion greatly reduces the density of the foam and increases its porosity at the microscopic level, so most foam articles can absorb impact energy through deformation or collapse. However, to better compress and absorb impact energy, compression in one direction is required, leaving room for expansion in the other direction. Therefore, increasing macroscopic cavities by defining the cavity structure helps foam articles achieve better performance. When foam cannot be further compressed during impact, bottom-out phenomenon occurs. As a result, objects experiencing bottom-out phenomenon suffer significant impact or acceleration, leading to damage or injury. This is a serious problem in helmet design; helmets that bottom out in standard impact tests may fail standard certification. By introducing macroscopic cavities within the helmet's shock-absorbing padding, the helmet's shock absorption effect can be improved, reducing the chance of bottoming out at certain impact velocities. A cavity structure can improve the impact absorption capacity of foam while reducing its weight and increasing its durability.

[0052] In one embodiment, a structure defined as a cavity reduces the average density of the foam product.

[0053] The defined cavity structure allows designers and engineers to select areas in foam products where more porosity or cavities are needed and design the foam products accordingly. Foam applications in safety, sensitive equipment, and transportation can particularly benefit from molding foam products using a defined cavity structure. Such applications can be envisioned as helmets and other body protection equipment, vehicle protective components (such as car bumpers), vehicle comfort components, aircraft components, boats, aircraft, or any other application of foam products.

[0054] In one embodiment, a structure defined as a cavity comprises one or more hollow compartments that may be interconnected or separated. This feature allows components requiring macroscopic cavities to be equipped with the exact number of cavities needed for a particular application.

[0055] In one embodiment, the cavity of the structure defined as a cavity within the mold is pressurized positively or negatively (compared to atmospheric pressure) during the molding process.

[0056] In one embodiment, during the molding process, a cavity-defined structure is placed in the mold such that the cavity-defined structure prevents the foam article portion formed on one side of the cavity-defined structure from joining with the foam article formed on the other side of the cavity-defined structure. In a next step, the mold is opened and the cavity-defined structure is removed, and then the two parts of the foam article are joined together by mechanical or chemical bonding methods or combinations thereof. One method of bonding the two parts involves closing the mold after removing the cavity-defined structure and introducing heat, steam, and pressure to bond the two parts of the foam article together.

[0057] In one embodiment based on the foregoing embodiments, the structure defined as a cavity is an inflatable structure comprising a non-stick material, such as silicone rubber or a coating, such that the structure defined as a cavity can be easily separated and removed from the components of the foam article after molding.

[0058] In one embodiment, as described in the two embodiments above, the foam product consists of two or more parts.

[0059] In one of the embodiments described in the last three embodiments above, the structure defined as a cavity is composed of more than one part.

[0060] In one embodiment, when expanded polymer microspheres are introduced into a mold, positive pressure is not allowed to be defined as the collapse of the cavity structure or a portion thereof due to heat, steam, and pressure applied during molding.

[0061] In one embodiment, the hollow compartments of the mold, defined as cavities, are pressurized after the molding process is complete. This embodiment allows the use of inflatable airbags with foam products.

[0062] In one embodiment, the hollow compartment of the structure defined as a cavity is sealed or contained before or after the molding process.

[0063] In one embodiment, the hollow compartment of the structure defined as a cavity is not sealed and contained before or after the molding process.

[0064] In one embodiment, the hollow compartment of the structure defined as a cavity is open.

[0065] In one embodiment, more than one molding process is required to form cavities in the final foam article. In the first molding, the foam article is molded to have the desired open cavities. In the next molding process, the foam with open cavities generated in the first molding is placed in a second mold. The cavities are then partially or completely covered by a cavity-defining structure in the form of a cover layer. A second molding is then performed. The cavity-defining structure does not allow polymer beads to enter the cavities formed in the first mold. This method creates the desired cavities for the final foam article.

[0066] In one embodiment, the above method can be used multiple times to create a multi-layered cavity.

[0067] In one embodiment, the structure defined as a cavity is a layer made of an adaptable flexible material.

[0068] In one embodiment, the structure defined as a cavity is a layer made of a rigid material.

[0069] In one embodiment, the structure defined as a cavity is a layer with spaced pores.

[0070] In one embodiment, the structure defined as a cavity is a layer of spaced-apart pores, such that the size or diameter of the pores in the layer is equal to or smaller than the average size or diameter of the polymer beads introduced into the mold. This arrangement prevents polymer beads from entering the cavity space formed by the foam article through the pores. Examples of materials for this layer include mesh fabrics, mesh plastics, and wire mesh. Using a layer with spaced-apart pores reduces the weight of the layer, improves adhesion between polymer beads placed on two opposite sides of the structural layer defined as a cavity, and prevents polymer beads from entering the cavity.

[0071] In one embodiment, a spaced-hole layer, which serves as a structure defined as a cavity in the helmet, covers the helmet's vents and acts as a safety screen or mesh for the vents, similar to an insect net.

[0072] In one embodiment, the cavity created during the first molding process is covered by a structure defined as a cavity, which is in the form of a layer of material that is conformable to cover the cavity during the second molding process. This material layer can be made by methods such as vacuum molding of plastic sheets or other materials.

[0073] In one embodiment, the foam article molded with an open cavity is covered by a structure defined as a cavity in the form of a cover layer, without introducing additional polymer beads on top of the structure defined as a cavity.

[0074] In one embodiment based on the foregoing embodiments, the cavity structure is attached to a molded foam article by mechanical or chemical connections, such as insertion, adhesives, heat and pressure, thermal bonding, co-molding, in-mold bonding, hook and loop connections, rivets, screws, stitching, straps, needles, holes, and combinations thereof. One application involves creating cavities in the outer surface (facing the head) of a helmet's shock-absorbing pad, and then covering the created shock-absorbing pad (foam article) with the helmet shell through adhesive or co-molding. The cavities formed in the shock-absorbing pad enhance the helmet's linear and rotational performance and reduce its weight.

[0075] In one embodiment, the cavity created by the structure defined as a cavity can be used to house sensors, wires, batteries, electronics, lights, or any other conceivable helmet device.

[0076] In one embodiment, the cavity may be used to house other types of dampers, such as thin-walled structures, trusses, auxiliary structures, lattices, or other damping structures, or to place them under or within a structure defined as a cavity.

[0077] In one embodiment, the above method can be used for components of vehicles (such as bumpers), car bodies, aircraft, ships, or any other conceivable application.

[0078] In one embodiment, two foam products with open cavities are manufactured using two molds and then joined together to form a single product with an internal cavity, thereby creating a cavity within the foam product.

[0079] In one embodiment, the cavity structure is created in a second molding process by firmly placing one or more plastic sheets onto an open cavity formed in the first molded foam article. Expanded polymer microspheres are then introduced into the mold to form the final foam article with the predetermined cavity.

[0080] In one embodiment, the structure defined as a cavity is a layer that is previously conformed to the required shape to cover the open cavity of the first foam article.

[0081] In one embodiment, inserts or anchors for connecting components such as chin straps, adjustment devices, or other helmet functions are connected to a structure defined as a cavity.

[0082] In one embodiment, prior to the second molding, shock-absorbing material, structure, or device, such as a gas-filled container or bladder, is placed in or connected to the created cavity via a structure defined as a cavity.

[0083] In one embodiment, prior to the second molding, shock-absorbing material, structure, or device, such as a gas-filled container, is placed in or connected to a structure defined as a cavity.

[0084] In one embodiment, sensors, electronics, wires, batteries, positioning devices, speedometers, cameras, reflectors, lights, ropes, chains, or other conceivable accessories are placed or attached to the cavity of the foam article, or to a structure defined as a cavity.

[0085] In one embodiment, the structure defined as a cavity and its extensions include plastics, organic polymers, synthetic polymers, ceramics, metals, polycarbonate plastics, acrylonitrile-butadiene-styrene (ABS) plastics, rubber, fabrics, fibers, Kevlar (for military or other applications because it does not tear), Teflon, silicone rubber, organic materials, synthetic materials, or combinations thereof. Depending on the application of the molded foam article, the structure defined as a cavity may be coated with adhesives, paints, or non-stick materials.

[0086] In one embodiment, after the molding process is complete, a structure defined as a cavity remains within the molded foam article. In this embodiment, this structure enhances the strength, durability, and / or shock absorption capabilities of the foam article.

[0087] In one embodiment, the structure defined as a cavity is removed after or before the final foam product is manufactured.

[0088] In one embodiment, a structure defined as a cavity includes inserts, connection holes, needle baskets, or anchors in a foam article for attaching to the foam in other ways.

[0089] In one embodiment, the protective headdress made of foam material is equipped with a structure defined as a cavity to improve its performance and durability.

[0090] In one embodiment, the helmet made of foam is equipped with a structure defined as a cavity, which reinforces the foam structure, making it more shock-absorbing and durable.

[0091] In one embodiment, in addition to forming a cavity in the helmet's shock-absorbing padding, the structure defined as a cavity also provides a means of connection for attaching accessories such as accessory pads, chin straps, and adjustment devices to the helmet, or for attaching accessories such as sensors, electronic devices, wires, batteries, positioning devices, speedometers, cameras, reflectors, ropes, chains, lights, or other conceivable helmet accessories to the helmet. Similarly, the structure defined as a cavity can provide fastening or connection methods for other applications such as sound insulation, heat insulation, construction, vehicles, aircraft, ships, and floating equipment protective components.

[0092] In one embodiment, the cavity created by the structure defined as a cavity is used to place or connect any conceivable accessory to meet a specific application.

[0093] In one embodiment, the cavity-defined structure within the foam article is removable and is removed after the foam article has been molded. This embodiment may include a flexible cavity-defined structure that is pressurized during molding and, after molding, can be removed from the opening of the foam article by depressurizing. In one embodiment, the structure comprises silicone rubber or is coated with a non-stick material (such as Teflon) to facilitate easy removal of the cavity-defined structure from the foam article after the molding process. In one embodiment, the flexible cavity-defined structure further includes a detachable or connected extension to hold the flexible structure in place during molding. In one embodiment, the detachable extension of the cavity-defined structure remains in the molded foam article.

[0094] In one embodiment, the cavity-defined structure comprises one or more solid or flexible components and is removed after molding. After removal of the cavity-defined structure, the portions of the foam article can be permanently or temporarily connected to each other to form the final foam article. In one embodiment, the cavity-defined structure used for molding can be replaced by another cavity-defined structure to provide additional benefits, such as structural reinforcement or providing an attachment for a specific application.

[0095] In one embodiment, a structure defined as a cavity allows for the creation of a foldable or stretchable object made of foam material.

[0096] In one embodiment, the foldable helmet is made using a structure defined as a cavity. The helmet may be made of multiple components that are interconnected via connections provided or facilitated by the cavity structure. Such connections include, but are not limited to, any mechanical connections such as buckles, straps, chains, rivets, hook-and-loop connections, locking mechanisms, and combinations thereof.

[0097] In one embodiment, the structure defined as a cavity reinforces the structure of the foam product. The foam may be fragile and easily broken. The structure defined as a cavity acts similarly to reinforcing steel bars in concrete, strengthening the structure of the foam product.

[0098] In one embodiment, a structure defined as a cavity includes perforations, holes, or openings at certain locations, which allows the structure to be better secured to and reinforced on the foam product, and also allows the structure defined as a cavity to be better secured within the foam product.

[0099] In one embodiment, the structure defined as a cavity is pressurized during molding, and perforations, holes, or openings in the structure are discharged at the openings where the gas (such as air or steam) meets the polymer beads, creating more cavities in the foam. This method can create additional cavities without increasing the size of the structure defined as a cavity. Furthermore, this embodiment reduces the weight of the manufactured foam article by creating more cavities in the foam while using structures of the same or lighter weight. The size of the additional cavities depends on the pressure of the gas in the structure defined as a cavity. Using high pressure increases the size of the additional cavities in the foam article on the outer surface of the structure defined as a cavity.

[0100] In one embodiment, the structure defined as a cavity has an extension to keep the structure fixed within the mold and prevent movement or misalignment during molding. The extension of the cavity structure can be solid or hollow, and it can be connected to or separated from other parts of the cavity structure. In one embodiment, the extension of the cavity structure prevents certain parts of the foam article from adhering to other parts of the foam article in certain areas. Therefore, it facilitates the removal of the cavity structure after molding and the manufacture of the final foam article by connecting parts of the foam article that are not defined as cavities.

[0101] In one embodiment, an extension of the structure defined as a cavity extends to the inner or outer surface of the mold. The extension maintains the position of the structure defined as a cavity during molding and prevents displacement of the structure during molding.

[0102] In one embodiment, the hollow space within a structure defined as a cavity, or the hollow space created by a structure defined as a cavity, is used to place or connect sensors, batteries, positioning devices, speedometers, cameras, lights, electronic components, ropes, belts, chains, wires, inserts, connectors for foam articles, or any other accessories required for foam article applications. An example of using a structure defined as a cavity is in the shock-absorbing padding of a helmet. Sensors, lights, electronics, batteries, wires, cameras can be placed in the hollow space of a structure defined as a cavity, or in the hollow space created by that structure in foam, or helmet components can be assembled, or parts of the helmet can be connected.

[0103] In one embodiment, a structure defined as a cavity is partially embedded in the foam and partially outside the foam. The portion of the structure outside the foam article can be used to mount and secure the foam article, connect multiple pieces of foam article together, or attach accessories to the foam. An example of application is in construction and insulation, where panels of foam articles can be joined together or attached to building structures to cover a large surface area, such as a ceiling or wall.

[0104] In one embodiment, a portion of the cavity structure is embedded in the foam, and a portion lies on the outer surface of the foam article. The cavity structure is partially embedded in the foam article and partially outside the foam article, allowing for further attachment to the foam article depending on its intended use. In one embodiment, the portion of the cavity structure outside the foam article has shock-absorbing properties.

[0105] In one embodiment, the portion of a structure defined as a cavity located inside or outside the foam product structure has shock-absorbing capabilities. For example, when the external or internal portion of a structure defined as a cavity is made of a thin-walled structure, truss, auxiliary structure, lattice, or other shock-absorbing structure, a multi-stage shock-absorbing design is formed.

[0106] In one embodiment, thin-walled structures, trusses, auxiliary structures, lattices, or other damping structures are placed in a hollow space (volume) created by a structure defined as a cavity to create a multi-stage damping design.

[0107] In one embodiment, a structure defined as a cavity includes interconnected hollow compartments.

[0108] In one embodiment, a structure defined as a cavity includes one or more mutually separated hollow compartments.

[0109] In one embodiment, the hollow compartment of the structure defined as a cavity is contained or sealed before or after the molding process.

[0110] In one embodiment, the hollow compartment is formed by a combination of a structure defined as a cavity and the introduction of a highly expandable material or formulation into a mold along with polymer beads. This material can create cavities larger than the microcavities within the beads, depending on the size of the introduced highly expandable material.

[0111] In one embodiment, the high-expansion material is in the form of solid particles of carbon dioxide (dry ice), nitrogen, or other materials or elements, exhibiting a high expansion rate between its solid / liquid and gaseous forms. The high-expansion material functions similarly to a structure defined as a cavity, expanding or sublimating due to heat during molding to form cavities in the foam product.

[0112] In one embodiment, a highly expandable material or element is used to create a cavity definition in a molded foam without introducing any additional structure that defines the cavity.

[0113] In one embodiment, the hollow compartment of the structure defined as a cavity is open, neither containing nor sealed.

[0114] In one embodiment, a structure defined as a cavity is used to manufacture any type of compressible foam product.

[0115] In one embodiment, a structure defined as a cavity is used as a shock-absorbing pad for a helmet to reduce the linear and rotational acceleration of the head upon impact.

[0116] In one embodiment, the cavity-defined structure may be partially exposed outside the final foam article to achieve specific application effects, such as connecting components in certain areas or protecting foam in other areas. One application is the design of cavity-defined structures for helmets, where certain areas of the helmet's interior that come into contact with the head are exposed on the helmet's inward-facing surface for housing and connecting helmet accessory padding. Such an arrangement can improve helmet performance and extend the durability of the connection method for body padding or other accessories.

[0117] In any of the foregoing embodiments, foam articles with a structure defined as a cavity can be used to make protective equipment, packaging, thermal insulation, sound insulation, flotation, space fillers, comfort pads, buildings, transportation equipment, vehicles, ships, aircraft or flying objects.

[0118] Go to Figure 1The image shows a cross-section of mold 17, within which a cavity structure 19 is placed prior to molding the foam article 18. In some applications, to secure the cavity structure 19 within mold 17 and prevent displacement during molding, the cavity structure 19 may include an extension or any other securing method. Depending on the application of the foam article 18, a hollow extension 31 or a solid extension 32 may be used. Extensions 31 and 32 may also reinforce the strength of the foam article 18. In one embodiment, mold 17 may include one or more openings 34 to pressurize the cavity structure during molding.

[0119] In one embodiment, the mold 17 may consist of multiple blocks, and the structure 19, defined as a cavity, may include an extension 35 exposed outside the mold 17 from an opening in the mold. The end of the extension 35 may be equipped with mechanical inserts, such as hooks and buckles, or other means, to attach the foam article to other foam articles or other objects. This embodiment facilitates the mounting of articles with minimal or no additional means of holding the foam article in place for application. Such embodiments can be used to mount foam articles, such as panels for insulation, impact protection (e.g., foldable helmets), comfort pads, flotation, construction, or other applications that may benefit from this arrangement.

[0120] In one embodiment, a cavity structure 19 is connected to one or more closed cavities 30, which are connected to the cavity structure 19 via a connector 29 under positive or negative pressure or atmospheric pressure.

[0121] In one embodiment, the cavity-defined structure 19 includes openings 24 at one or more locations within the cavity-defined structure 19. During molding, the cavity-defined structure 19 can be subjected to positive or negative pressure through the openings 34. If the cavity-defined structure 19 is positively pressurized by a gas such as air or vapor, the pressure within the cavity-defined structure 19 allows for the formation of more cavities at the openings 24 of the foam article 18. This allows for an increase in the cavity volume within the foam article 18 without increasing the size of the cavity-defined structure 19. If the cavity-defined structure 19 is negatively pressurized, the foam article 18 can partially or completely enter the cavity-defined structure 19, which can strengthen the foam article 18 and securely hold the cavity-defined structure 19 within the foam article 18.

[0122] The mold may include vents for steaming or venting air from within the mold. Figure 1 Or other drawings not shown, to keep the drawings from being interfered with by existing technical information.

[0123] In one embodiment, a foam article 18 containing a structure 19 defined as a cavity is used for flotation. In such an embodiment, the structure 19 defined as a cavity is placed within a mold 17 before expanding polymer microspheres are introduced to manufacture the foam article 18. The resulting foam article 18 can have better buoyancy, better strength, better durability, and also has built-in connections in the extension 35. In one embodiment, the extension 35 can be used to attach the foam article to other foam articles, ships, docks, coastlines, and any other conceivable marine application of the foam article 18. Once molded, the opening 34 can be closed or plugged.

[0124] Go to Figure 2 The diagram illustrates a cross-section of a helmet 14 worn on the head 13, including an outer shell 10 and a shock-absorbing pad 11. In one embodiment, the shock-absorbing pad 11 is equipped with a structure 12 defined as a cavity at one or more locations to improve helmet performance by reducing the linear and rotational acceleration of the head 13. In one embodiment, the structure 12 defined as a cavity includes a solid extension 38 and / or a hollow extension 39 at one or more locations to securely place the structure 12 defined as a cavity within the mold during molding.

[0125] In one embodiment, the extension 37 facilitates the separation of the damping pad 11 into multiple pieces for removal of the structure 12 defined as a cavity after molding. Then, the multiple damping pads 11 ( Figure 2 (Not shown in the text) will be joined together using any mechanical or chemical connection method, such as pressure, heat, in-mold, co-mold, adhesive, buckle, and combinations thereof.

[0126] In one embodiment, the extension 37 is not included in the foam article so that the fragments of the shock-absorbing pad 11 (in) Figure 2 (Not shown in the image) can adhere together.

[0127] In one embodiment, the structure 12 defined as a cavity includes an opening 15 for pressurizing the structure defined as a cavity during the molding process.

[0128] In one embodiment, a structure 12 defined as a cavity reaches the inner surface 40 of the helmet 14 at one or more locations 41.

[0129] In one embodiment, the structure 12, defined as a cavity, includes solid extensions 37, 38 and / or hollow extensions 39 at one or more locations to reinforce the structure of the helmet 14.

[0130] In one embodiment, the structure 12 defined as a cavity includes other connection methods typically used in foam molding to maintain the position of the structure 12 defined as a cavity during molding.

[0131] In one embodiment, one or more extensions 37, 38, and 39 reach the outer surface of the shock-absorbing pad, such as the inner surface 40 of the helmet 14 or the outer shell 10, and include a connecting device at the end portion of the extensions 37, 38, and 39 that connects to other parts of the helmet, such as the inner shell or the comfort pad in the helmet.

[0132] In one embodiment, the extensions 37, 38 and 39 may have shock-absorbing capabilities.

[0133] In one embodiment, the extensions 37, 38, and 39 reach the outer or inner surface of the helmet 14.

[0134] In one embodiment, the extension 37, 38, or 39 may cover an area of ​​the inner surface 40 and provide a surface for placing and / or connecting fitting pads. Figure 2 (Not shown in the image) or other components, such as the adjustment system, and the helmet's chin strap.

[0135] In one embodiment, the structure 12 defined as a cavity, or its extensions 37, 38, or 39, are used to accommodate a fitting gasket. Figure 2 (Not shown) is connected to helmet 14. For example, the padding can be easily attached to helmet 14 by providing a connection method such as inserts, rivets, pins, hook and loop connections, pin baskets, or holes in a structure 12 or its extensions 37, 38, or 39 that is defined as a cavity in a similar location 41.

[0136] In one embodiment, helmet components, such as accessory padding, chin strap, adjustment system, sensors, cameras, adjustment mechanisms, ropes, chains, or other conceivable accessories (in... Figure 2 (Not shown in the image) is connected to structure 12, which is defined as a cavity, or its extensions 37, 38, and 39.

[0137] In the molding process of foams, for some foams such as EPS, vapor enters or exits the foam product through special vents during molding. For the sake of simplicity and clarity in the accompanying drawings, details understood by those skilled in the art are not shown or explained.

[0138] In one embodiment, the structure 12 defined as a cavity includes an opening or hole 42 to increase or decrease the cavity in the foam of the shock-absorbing pad 11 by applying pressure in a positive or negative direction from the opening 15 of the structure 12 defined as a cavity during the molding process.

[0139] In one embodiment, the structure 12 defined as a cavity can be any form and shape described in the preceding embodiments and can be used in helmets or other applications.

[0140] Go to Figure 3The image shows a cross-section 50 (crown / front view) of a portion of the helmet, comprising an outer shell 51, a first-part shock-absorbing liner 52 including a cavity 53 formed during a first molding process. A structure 54, defined as the cavity, is a covering layer that covers the cavity 53 during a second molding process to prevent polymer beads from entering the cavity 53 during molding. A second-part shock-absorbing liner 56 is formed on top of the structure 54, defined as the cavity, during the second molding process. The design, similar in cross-section to cross-section 50, is similar to the structure of a skeleton, which can improve helmet performance by reducing the linear and rotational acceleration of the head upon impact. It also reduces the number of polymer beads used in the helmet, thus reducing its weight. The use of the structure 54, defined as the cavity, in the design reinforces the structure shown in cross-section 50.

[0141] In one embodiment, the structure 54 defined as a cavity can be flat, free-form, or curved toward or away from the cavity 53, as well as combinations thereof.

[0142] In one embodiment, the structure 54, defined as a cavity, includes one or more holes 55 to allow the first portion of the damping pad 52 to bond to the second portion of the damping pad 56 during the second molding process.

[0143] In one embodiment, the hole 55 is placed on a portion or the entire surface of the structure 54, which is defined as a cavity.

[0144] In one embodiment, the hole 55 creates a mesh surface with spaced holes for the structure 54, which is defined as a cavity.

[0145] In one embodiment, the average diameter of the hole 55 is equal to or less than the average diameter of the polymer beads introduced into the mold.

[0146] In one embodiment, one or more holes 55 are placed on a matching protruding stud. Figure 3 (Not shown in the image), these studs have been created in the first damping pad 52 to firmly hold the structure 54, which is defined as a cavity, in place during the second molding process.

[0147] In one embodiment, the structure 54, defined as a cavity, is a flexible or adaptive material.

[0148] In one embodiment, the structure 54, defined as a cavity, is a flexible mesh layer composed of spaced holes.

[0149] In one embodiment, the width of the first damping pad 52 and the second damping pad 56 at their junction with the structure 54 defined as a cavity is wider than the width of the structure 54 defined as a cavity. This feature allows the first damping pad 52 and the second damping pad 56 to directly engage with each other at certain locations, while also allowing the structure 54 defined as a cavity to be concealed within the final foam product.

[0150] In one embodiment, the structure 54, defined as a cavity, is coated with an adhesive or paint to better bond with the first portion damping pad 52 and / or the second portion damping pad 56.

[0151] In one embodiment, a helmet or any other object that benefits from this arrangement may use the same design as shown in cross-section 50 in a row or interlayer, with or without shell 51 between them.

[0152] In one embodiment, cross section 50 belongs to a foam product for applications such as insulation, buoyancy, construction, packaging, or any other conceivable foam product application, which may be equipped with or without a shell 51, and is defined as a cavity structure 54.

[0153] In one embodiment, cross-section 50 belongs to a foam product for construction, which may or may not have a shell 51, such that a large number of cavities 53 are adjacent to each other, with foam walls similar to the first part of the shock-absorbing pad 52 in between, resembling a cavity array (grid-like). These cavities (i.e., cavities 53) can have connected volumes or be self-contained. In one embodiment, each cavity 53 in the cavity array is self-contained. This makes the foam product suitable for applications such as construction, where custom-made and cut foam is typically required when filling spaces of fixed dimensions with block or sheet-like materials.

[0154] Go to Figure 4 The image shows a cross-section 46 (crown / front view) of a helmet portion, comprising a structure 44 defined as a cavity, which functions as an outer or inner shell, a cavity 47, and a shock-absorbing pad (foam article) 45. In one embodiment, the shock-absorbing pad 45 is formed to include the cavity 47. In a next step, the structure 44 defined as the cavity is attached to the shock-absorbing pad 45 using mechanical or chemical bonding methods, such as co-molding, in-mold molding, heat, pressure, adhesives, inserts, pins, screws, straps, rivets, or combinations thereof.

[0155] In one embodiment, the structure 44 defined as a cavity reinforces the structure of the foam article. Without the structure 44 defined as a cavity, the shock-absorbing pad 45 would be fragile and easily damaged. When the structure 44 defined as a cavity is added to the foam structure, the foam article 46 with the properly sized cavity 47 can absorb impacts as well as, or better than, a similar foam structure without the cavity 47.

[0156] In one embodiment, Figure 4 The object shown can be any protective equipment for the body or head, or foam products used for vehicle protective parts (such as car bumpers), vehicle comfort parts, aircraft parts, boats, flying objects, or any other application.

[0157] In one embodiment, shock-absorbing pads 45 and an array of cavities similar to cavities 47 are placed adjacent to each other to form the final shape of the foam article.

[0158] Go to Figure 5 The diagram shows a cross-section 69 (sagittal view) of a helmet 66 above the head, which includes an outer shell 60, a first part shock-absorbing pad 61, a second part shock-absorbing pad 64, one or more cavities 63, and a structure 62 defined as a cavity.

[0159] In one embodiment, the first portion of the damping pad 61 is manufactured together with the housing 60 to have a cavity 63 in the damping pad 61. Then, in the next molding process, before introducing polymer beads into the mold to manufacture the second portion of the damping pad 64, a structure 62 defined as a cavity is added to cover the cavity 63.

[0160] In one embodiment, the cavity 63 is defined by including a raised region 67 in the first portion of the damping pad. The raised region 67 can be of any shape and form and can approach or reach the structure 62 defined as the cavity.

[0161] In one embodiment, the raised region 67 serves as a partition wall between cavities 63, providing the cavity with the required structure and a certain strength for a specific application.

[0162] In one embodiment, the raised region 67 provides support to securely hold the structure, defined as a cavity, in place.

[0163] In one embodiment, the structure 62, defined as a cavity, has holes 68. These holes can be placed in any configuration or shape. The holes 68 can improve the adhesion between the first portion of the shock-absorbing pad 61 and the second portion of the shock-absorbing pad 64. It can also reduce the weight of the structure 62 defined as a cavity. The size of the holes 68 can be selected to be the same as or smaller than the average size of the polymer beads introduced into the mold during the second molding process.

[0164] In one embodiment, the structure 62 defined as a cavity is a flexible or adaptive layer.

[0165] In one embodiment, the structure 62, defined as a cavity, is a rigid layer.

[0166] In one embodiment, structure 62, defined as a cavity, includes fabric, plastic, metal, or fiber.

[0167] In one embodiment, the structure 62 defined as a cavity is a mesh layer or wire mesh layer with spaced holes or openings.

[0168] In one embodiment, a foam article made by using a structure defined as a cavity is a foam made of any type of pre-expanded beads or a foam made of other forms or shapes of foam components.

[0169] While embodiments have been described and illustrated, it is understood that various changes may be made therein without departing from the spirit and scope of the invention. Any feature described in either the singular or plural form may be used in both the singular and plural forms in a particular application.

Claims

1. A method for manufacturing foam products, characterized in that, The method is as follows: An independent, pre-formed structure defined as a cavity is provided in the mold, the structure defined as a cavity including holes or openings, and expanded polymer microspheres are molded to fuse and form a foam matrix, thereby forming a macroscopic cavity inside the foam product that corresponds to the shape of the structure defined as a cavity; The structure defined as a cavity includes at least one of the following features: An object having an open cavity or an object having a closed cavity; Wherein, the structure defined as a cavity is in contact with the expanded polymer microspheres or the foam matrix on its outer surface during the molding process, and the size of the pores and openings in the structure defined as a cavity is smaller than the average size of the polymer beads.

2. The method according to claim 1, characterized in that, When a covering layer is used as a structure defined as a cavity in a foam product, the molding process is carried out in two or more stages.

3. The method according to claim 1, characterized in that, When an object with an open cavity or an object with a closed cavity is used as a structure defined as a cavity in a foam product, the molding process is completed in one stage.

4. The method according to claim 2, characterized in that, The molding of the expanded polymer microspheres and the cavity-defined structure is completed in multiple molding processes, wherein: In the first molding process, foam products with open cavities are produced; In the second molding process, partially or completely open cavities are covered by a cavity structure, and then expanded polymer microspheres are placed into the mold to close the cavity structure.

5. The method according to claim 3, characterized in that, The molding of the expanded polymer microspheres and the cavity-defined structure is completed in a single molding process, wherein the cavity-defined structure is placed in the mold before the expanded polymer microspheres are placed in the mold so as to form cavities in the foam product that conform to the cavity-defined structure.

6. The method according to claim 1, characterized in that, The cavity structure, defined as a cavity, or the cavity formed in the foam product by the cavity structure defined as a cavity, is subjected to positive or negative pressure during the molding process.

7. The method according to claim 1, characterized in that, During the molding process, the structure defined as a cavity is pressurized, and gas or vapor is released into the polymer beads through the holes and openings in the structure defined as a cavity, forming additional cavities in the foam product.

8. The method according to claim 1, characterized in that, Sensors, cameras, lights, batteries, wires, plugs, ropes, or chains are placed in cavities created by a structure in a foam product that is defined as a cavity.

9. The method according to claim 1, characterized in that, Use a flexible shell to cover foam products for helmet use.

10. A foam article, obtained by the method according to any one of claims 1-9.

11. The foam product according to claim 10, characterized in that, The expanded polymer microspheres are adapted to the shape of a structure defined as a cavity to form a cavity.

12. The foam product according to claim 10, characterized in that, Foam products with open cavities are defined as those whose cavities are partially or completely covered by the structure.

13. The foam product according to claim 12, characterized in that, Expandable polymer microspheres are defined as having a cavity structure divided into first and second parts, the structure including a sheet covering the first part to form the cavity.

14. The foam product according to claim 10, characterized in that, The structure defined as a cavity includes holes or openings.

15. The foam product according to claim 10, characterized in that, The dimensions of the pores and openings in the structure defined as a cavity are smaller than the average size of the polymer beads.

16. The foam product according to claim 10, characterized in that, The cavity structure is made of a material selected from one or a combination of the following: Organic polymers, ceramics, metals, or combinations thereof.

17. The foam product according to claim 14, characterized in that, The structure defined as a cavity has an opening, and additional cavities are formed in polymer microspheres on the outer surface of the structure defined as a cavity.

18. The foam product according to claim 10, characterized in that, The foamed product is used for any of the following purposes: vehicle parts, ship parts, aircraft parts.

19. The foam product according to claim 10, characterized in that, The cavity structure is made of a synthetic polymer.

20. The foam product according to claim 16, characterized in that, The cavity structure is made of rubber.

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