Method for manufacturing a product of a multi-gradient foamed polymer material

Abstract

1. A method for manufacturing an article formed from a foamed polymeric material, comprising the steps of: creating, via software, a virtual model (M) of the product to be manufactured from the solid foamed polymer material; performing topology optimization of the virtual model (M) via software to obtain an optimized virtual model (MO) having multiple regions with different relative densities; providing said foamable polymer material and placing said material in a mold (1); solubilizing under pressure at least one blowing agent in the expandable polymeric material placed in the mold (1), using a pressure profile of the blowing agent that can vary based on time and / or space as a function of the topology optimization; Releasing the pressure to obtain a product (S) formed from the foamed polymer material having a plurality of regions of different relative densities; Removing the product (S) formed from the foamed polymer material from the mold (1).

Description

Technical Field

[0001] (Field of the Invention) The present invention relates to a method (or process or procedure) for forming (or manufacturing) a product of a multi-gradient (or multi-slope) foamed polymer material (or foamed polymer material), that is, a product having a plurality of different regions (or a plurality of distinct regions or differentiated regions) with respect to the density of the material and / or the pore size distribution (or pore diameter distribution or pore size distribution) (morphology (or form)). In particular, by means of such a method, an optimized product (an optimized product with respect to structure and / or function (e.g., rigidity, strength, elasticity, shock absorption performance, heat insulation performance, sound absorption performance)) can be formed (or manufactured). By means of such a method, it is possible to distribute (or allocate or distribute) the material only to the parts that are strictly required for the product. For such a purpose, software for topology optimization is used. This involves a procedure for manufacturing a foamed polymer material that can form (or manufacture) a multi-gradient density and / or morphology (or form). Such a procedure includes solubilization of a physical blowing agent. The blowing agent is necessary for foaming the above material. Such a procedure is characterized (or characterized) by conditions (or conditions) that vary based on time and / or space (or together with time and / or space), and is further characterized (or characterized) by a function of topology optimization created (or formed) in advance (or a function of topology optimization of a preliminary preform (or function)). More specifically, a non-uniform profile of the concentration of the physical blowing agent is created (or formed or generated) in the polymer by conditions (or conditions) that can vary based on time and / or space (or together with time and / or space) in the solubilization step (or step), and a non-uniform density and morphology (or form) are created (or formed or generated) in the product upon expansion. This corresponds to what is defined by topology optimization.

Background Art

[0002] (Current State of the Art) In recent years, there has been growing interest in foamed materials (or foamed materials) having a "gradient (or slope)". The structural and functional characteristics are improved compared to those of foamed materials characterized by a uniform structure in terms of cell density and / or morphology (or form). This has been demonstrated both theoretically and experimentally by recent scientific research. Scientific literature describes methods (or processes or procedures) for producing such layered foamed structures, i.e., foamed structures having a gradient (or slope) of morphology (or form) and / or density, as well as methods for obtaining such foamed structures.

[0003] For example, Zhou C. et al. examined the use of "non-equilibrium profiles of the concentration of the foaming agent" in "Fabrication of functionally graded porous polymer via supercritical CO2 foaming", Composites: Part B 42 (2011) 318-325. In this method, through the solubilization step (or step), the material to be foamed (or material that can be foamed) is partially saturated with the foaming agent. This occurs at a constant pressure and a constant temperature over a time shorter than the time required to reach a uniform concentration of the foaming agent. In this case, the more distant part (or more remote part) of the sample (the foamed sample) (the more distant part (or more remote part) with respect to the free surface in contact with the foaming agent under pressure, i.e., the more inner part) contains a lower concentration of the foaming agent compared to the part adjacent to the surface (the more outer part). Here, the concentration of the foaming agent easily reaches an equilibrium state with the external pressure of the foaming agent.

[0004] As a result, the inner part (or interior) of the sample has little or no foaming. On the other hand, the outer part (or exterior) will be fully foamed. The design of such a type of structure is assumed to be known for the diffusion coefficient of the blowing agent in the polymer and is available in many polymer / blowing agent systems.

[0005] The described method, even if simple to achieve, is quite limited. This is because it is only possible to manufacture a foamed material (or foamed material) with a single gradient (or gradient) having the characteristic that there is less foamed layer inside the sample and more foamed layer outside.

[0006] M. Trofa, E. Di Maio, P.L. Maffettone showed the possibility of generating (or forming) a layered polymer foam (or polymer foam) with a gradient (or gradient) by using foaming technology in "Multi-graded foams upon time-dependent exposition to blowing agent", Chemical Engineering Journal 362 (2019) 812-817. This technique involves solubilizing one or more blowing agents under pressure in a foamable polymer material. At this time, the pressure profile of the above one or more blowing agents is used. Such a pressure profile can change based on time (or can change over time or with time). That is, it is by introducing conditions (or conditions) that can change based on the time of the gas adsorption step (or step) (or conditions that can change over time or with time) in the foamable polymer material.

[0007] Also, currently, software for topology optimization is known. Such software has been achieved in the field of computer-aided production engineering (CAE) and has greatly developed in the field of additive manufacturing. Additive manufacturing is a method (or process) of manufacturing an object (or body or object) from a 3D model (or three-dimensional model) created by a computer, thereby bonding (or joining) materials. For example, in the academic paper "Strutture leggere: ottimizzazione topologica e stampa 3D" ["Lightweight structures: topology optimization and 3D printing"] by N. Manfredi, Universita Degli Studi di Pavia, Facolta di Ingegneria, Corso di Laurea Magistrale in Ingegneria Civile, anno accademico 2014-2015 [University of Pavia, Faculty of Engineering, Civil Engineering graduate program, academic year 2014-2015], the code for topology optimization of structures made of lattice materials (or lattice materials) and the manufacturing of such structures optimized by 3D printing are described. According to such a paper, it is clearly described that foams (or foams) are not suitable for the optimization process, "unlike lattice materials". This is because foams (or foams) are characterized by a high degree of randomness in the cell distribution, size, and shape.

[0008] Also, these days, for example, it is known that by adopting laminations of various materials with different rigidities, the performance (or performance) required of a component (or ingredient or component) can be obtained. On the other hand, using various materials makes recycling of the component very difficult (although not impossible).

[0009] (Definition) The expression "polymer material" refers to a polymer material comprising a homopolymer or a copolymer. Such a polymer material is thermoplastic or thermosetting.

[0010] The expression "foamable polymer material (or polymer material capable of foaming)" refers to a polymer material that can absorb a foaming agent under specific temperature and pressure, can form nuclei of bubbles (or bubbles) when the pressure is released, and can withstand tensile stress during the growth of a plurality of bubbles (or bubbles) and then solidify.

[0011] The expression "foaming agent" refers to a substance that can cause expansion of a polymer material by forming a plurality of bubbles (or bubbles) in the polymer material.

[0012] The term "density" refers to the ratio of the weight of a polymer material having a predetermined volume (or volume or volume) to that volume (or volume or volume).

[0013] The term "morphology (or form)" refers to the shape (or shape), dimensions (or size), and number per unit volume (bubble density) of a plurality of bubbles (or bubbles) formed in a foamed polymer material (or foamed polymer material), as well as the local distribution (or distribution or distribution) of the polymer between the bubble walls (or walls) and the pillars (or pillars).

[0014] The term "foamed polymer material (or foamed polymer material)" refers to a polymer material that contains a plurality of bubbles (or bubbles) formed by a foaming agent inside thereof.

[0015] Therefore, the density of the foamed polymer material (or foamed polymer material) also depends on the morphology (or form) of the plurality of bubbles (or bubbles) formed in the above foamed polymer material (or foamed polymer material) and the number of such bubbles.

[0016] In the scope of this specification and the appended claims, "relative density" is intended to mean the ratio of the density of a foamed polymer material (or foamed polymer material) having a predetermined volume to the density of the same solid polymer material having the same volume (i.e., a non-foamed material in which no bubbles (or bubbles) are present).

[0017] The term "topological optimization (or topological optimization or topological optimization)" defines a study, which is performed by software. By this study, in a part (or component or component), the mass distribution (or distribution or distribution) can be redefined on a scale (or unit) of millimeters (mm) or micrometers (μm), and can be maintained without changing the visible shape (or geometry). Therefore, the weight reduction of the part (or component or component) becomes possible. That is, its specific performance (or performance) can be improved. By topological optimization, the combination (or set) of the masses used can be utilized in an organic manner (or method or manner). This synergistically cooperates with the performance (or performance) of the part (or component or component).

[0018] By this method, the outer shape (or shape) of the part (or component or component) can be maintained. This method respects the productivity constraints (or constraints), reduces the weight during use (or role), and still ensures the initial mechanical performance (or initial mechanical performance). Through topology optimization, the optimal distribution (or distribution or distribution) of materials is considered in the constrained design space. In the scope of this specification and the appended claims, "optimization of the topology of the foamed polymer material (or foamed polymer material)" is intended to mean a software-based calculation that can redefine the distribution (or distribution or distribution) of the mass of the structure in the above foamed polymer material. As a result, the structure can be made lighter. By optimizing the topology of the structure of the foamed polymer material, it becomes possible to define the density gradient (or density gradient) of the above foamed material (that is, the shape (or shape), dimensions (or size) and number per unit volume of the bubbles (or bubbles)). This is to obtain a high-performance (or high-performance), sustainable (or sustainable), lightweight (or light) structure. The design (or design) process (or step) includes the design (or design) of the volume (or volume or volume) of the structure, the definition of stress (or stress), the properties (or properties) of the foamable polymer material (a solid material that is not yet porous), and the conditions (or conditions) of the constraints (or constraints). Then, start the topology optimization. This is to obtain a virtual conceptual structure (or virtual structure) (having the same shape and volume, but having different morphologies (or morphologies) and densities, that is, having the morphology (or morphology) and density gradient (or density gradient) of the foamed polymer material).

[0019] The term "virtual" relates to the structure and is intended to mean a structure simulated by a computer.

Summary of the Invention

Problems to be Solved by the Invention

[0020] (Summary of the Invention) The applicant felt the need to produce (or form) a polymer foam (or polymer foam) product that is more complex (or complex), more high-performance (or high-performance), more sustainable (or sustainable), and lighter (or light) compared to products that can be obtained by prior art methods.

[0021] In particular, the applicant has set as an objective to propose a method (or process or process) for manufacturing (or forming) a polymer foam product (or polymer foam product) having the above characteristics. Further, this method (or process or process) is rapid and relatively inexpensive.

[0022] In addition, the applicant has set as an objective to manufacture polymer foam products (however, they are very different from each other, and belong to various fields, and are diversified by using the same principle).

[0023] Therefore, the applicant has set as an objective to propose a method (or process or process) for manufacturing a polymer foam product (however, it is flexible (or flexible) and optimizes the use (or application) of materials).

Means for Solving the Problems

[0024] The applicant has found that the above and further other objectives can be substantially achieved by using software for optimizing topology in combination with specific technologies to obtain a multi-gradient polymer foam. In the multi-gradient polymer foam, the morphology (or form) and density gradient (or density gradient) are designed (or designed) by using the above software for optimizing topology, together with the orientation (or orientation) of the pores (or pores or pores or pores).

[0025] In particular, Applicant has found that the above and further other objects can be substantially achieved by a method (or process or procedure) according to one or more of the appended claims and / or a method (or process or procedure) according to one or more of the following aspects.

[0026] According to a first aspect, the present invention relates to a method (or process or procedure) for manufacturing a product (or article) of a multi-gradient foamed polymer material (or foamed polymer material).

[0027] The method (or process or procedure) includes the following steps (i) to (vii). Step (i) Creating a virtual model (or digital model) of a product that can be manufactured from a solid foamable (or foamable or formable) polymer material (i.e., an unfoamed polymer material) via software. Step (ii) Applying (or assigning) constraints (or limitations) and / or loads (or forces) required (or defined) by the application (or use) and optimizing the topology of the virtual model via software to obtain an optimized virtual model having a plurality of regions with different relative densities and / or a plurality of regions with different morphologies. Step (iii) Preparing the solid foamable polymer material. Step (iv) Placing the solid foamable polymer material into a mold (or die or form or casting). Step (v) A step of solubilizing at least one blowing agent in the solid foamable polymer material placed in the mold under pressure, using a pressure profile (or pressure profile) of the at least one blowing agent that can vary based on time (or time) and / or space (or space) (or can vary with time and / or space) as a function of the optimization of the topology. Step (vi) a step of releasing pressure to obtain a product of a foamed polymer material having a plurality of regions with different relative densities and / or a plurality of regions with different morphologies, and Step (vii) a step of removing (or taking out or detaching) the product of the foamed polymer material from the mold.

[0028] According to a second aspect, the present invention relates to a product formed (or manufactured) from a foamed polymer material manufactured according to the method (or process or procedure) of the first aspect and / or according to one or more aspects listed below in this specification.

[0029] The step of "solubilizing a blowing agent under pressure in a polymer material (or solubilization or solubilization)" means that a blowing agent (such a blowing agent has already been introduced under pressure into a mold containing a foaming polymer material) penetrates into the polymer material and saturates such a polymer material (that is, the foaming polymer material absorbs the blowing agent). By doing so, when the pressure of the blowing agent is released, a plurality of bubbles (or bubbles) are formed in the polymer material, grow, and then foam.

[0030] The term "pressure profile (or pressure profile) of at least one blowing agent that can vary based on time (or time) and / or space (or space) (or can vary with time and / or space)" is intended to mean that the pressure of the blowing agent (such a blowing agent is introduced into the mold and acts on the foaming polymer material) can be varied based on time (or with time) according to a predefined profile (for example, a profile designed (or designed) for a specific foamed product). Further, a value that can vary based on space (or space) (or can vary with space) can be assumed (or inferred) by the same pressure as a function of the surface portion of the foaming polymer material. The pressure profile(s) of the blowing agent is (are) calculated starting (or starting) from the result of a topology optimization performed in advance, and determines the shape (or shape), dimensions (or size), and number per unit volume of a plurality of bubbles (or bubbles) formed in the foaming polymer material. Accordingly, the local density of the foaming polymer material is determined. The density of the foamed polymer material can be defined for each region (or for each area or area) or for each point (or for each point) at the design stage (or design phase).

[0031] The applicant has demonstrated that a product formed from a foamed polymer material provided with a density gradient (or density gradient) and / or morphology (or morphology) can be manufactured by a method (or process or process) according to the present invention. By doing so, the performance (or performance) is maximized and the weight is minimized. In other words, according to the steps (or steps) of solubilization and foaming, the foamed polymer material has an average relative density lower than 1 (that is, lower than the density of the starting (or starting) solid foaming polymer material), a density gradient (or density gradient) or a morphology gradient (or morphology gradient or morphology gradient) (the relative density is uniform and less than 1), or both a density gradient and a morphology gradient.

[0032] In the present disclosure, the Applicant has demonstrated that by using the same polymers with different densities and / or morphologies (or morphologies), similar results can be obtained where layers with different rigidities are bonded, and recyclability (or recyclability) is ensured. This is because it is a single material.

[0033] The Applicant has also demonstrated that a complex product having the above characteristics can be manufactured by a method (or process or procedure) according to the present invention.

[0034] The Applicant has also demonstrated that such a product can be manufactured in a relatively simple and rapid manner (or method or manner) by a method (or process or procedure) according to the present invention.

[0035] The Applicant has also demonstrated that it is applicable in very different fields by a method (or process or procedure) according to the present invention (for example, furniture, ships, automobiles, clothing, architecture, etc.).

[0036] Further aspects of the present invention are listed below.

[0037] In one aspect, step (i) (creating a virtual model of a product that can be manufactured from a solid foaming polymer material via software) is performed by a software calculation program (for example, Autodesk (登録商標) by Autocad (登録商標) or 3D design by Ansys (登録商標) ).

[0038] In one aspect, step (ii) (optimizing the topology of the virtual model via software to obtain an optimized virtual model having a plurality of regions with different relative densities) includes the following. Defining the properties of the foaming polymer material and the stress (or strain) and constraint (or restraint) conditions (or conditions) of the product that can be manufactured. Redefining the mass distribution (or distribution or allocation) of the product that can be manufactured as a function of the properties of the foaming polymer material, the stress (or strain), and the constraint (or restraint) conditions (or conditions).

[0039] In one aspect, the virtual model of the product that can be manufactured from the solid foaming polymer material and the optimized virtual model having a plurality of regions with different relative densities and / or a plurality of regions with different morphologies (or forms) have the same shape and still occupy the same volume (or volume or volume). The relative density of the virtual model of the product that can be manufactured from the solid foaming polymer material is equal to 1 everywhere. The optimized virtual model (having a plurality of regions with different relative densities and, optionally, a plurality of regions with different morphologies (or forms)) can have a relative density (density gradient (or density gradient)) that varies based on space (or varies with space). The relative density of the optimized virtual model having a plurality of regions with different relative densities is less than 1. Optionally, it is equal to 1. Optionally, this relative density is included between 0.01 and 1.

[0040] In one aspect, step (iii) (the step of preparing the foaming polymer material) includes the following. Manufacturing a preform from the solid foaming polymer material.

[0041] In one aspect, the manufacture of the preform includes the following. Injection molding the preform or using other techniques (e.g., compression molding (or compression molding), blow molding (or blowing), rotational molding (or rotomolding), etc.).

[0042] In one aspect, step (iv) (placing (or inserting) the foamable polymer material into the mold) includes the following. Placing the preform into the mold, more precisely, placing it into the internal chamber of the mold.

[0043] In one aspect, the mold has the final shape of the product of the foamed polymer material (or the foamed polymer material).

[0044] In one aspect, the preform has a volume (or capacity or volume) smaller than the volume (or capacity or volume) of the product of the foamed polymer material (or the foamed polymer material).

[0045] As one aspect, the preform has a shape different from the final shape of the product of the foamed polymer material (or the foamed polymer material).

[0046] In one aspect, the preform has a shape similar to the shape obtained by topology optimization. In particular, with respect to a plurality of regions having a relative density equal to 1, it has a shape similar to the shape obtained by topology optimization.

[0047] In one aspect, the mold has at least one inlet (or entrance) and at least one outlet (or exit), which are in fluid communication with the chamber and are for introducing or discharging at least one blowing agent.

[0048] In one aspect, the mold is partitioned inside. That is, the chamber of the mold has an internal separator, which divides the chamber into sub-chambers.

[0049] In one aspect, different blowing agents (having the same pressure profile or different pressure profiles) or the same blowing agent (having different pressure profiles) are introduced into different sub-chambers.

[0050] In one aspect, each sub-chamber comprises an inlet (or entrance) and an outlet (or exit), each for introducing or discharging the blowing agent(s) respectively.

[0051] In one aspect, prior to at least step (v) (a step of solubilizing at least one blowing agent under pressure in a foaming polymeric material disposed in a mold, using a pressure profile of at least one blowing agent that can vary (or vary with) time and / or space as a function (or function) of topology optimization), a preform disposed in the mold partially fills the mold, leaving (or providing or forming) an empty volume (or empty volume (or volume or volume) or empty volume). This is to allow for the expansion of the foaming polymeric material during step (vi) (a step of releasing pressure to obtain a product of a foamed polymeric material having a plurality of regions of different relative densities). In other words, the preform (constituted by a solid polymer (i.e., unfoamed) for which it is desired to obtain a final product) only partially fills the final mold, leaving (or providing or forming) an empty volume (or empty volume (or volume or volume) or empty volume). Only by a subsequent foaming step is such an empty volume (or empty volume (or volume or volume) or empty volume) filled with the foam of the foamed polymer.

[0052] In one aspect, in an optimized virtual model, a plurality of regions that are virtually darkened (however, the relative density is less than 1) are provided. And only a plurality of regions with a relative density equal to 1 are left (or provided or formed) so as to be clearly visible to the eye. Here, the preform to be manufactured includes a plurality of regions left (or provided or formed to be visible to the eye) with a relative density equal to 1, and additional materials distributed (or allocated or apportioned) to generate (or form) a plurality of regions with different relative densities (less than 1) when foamed.

[0053] In one aspect, starting from (or beginning with) an optimized virtual model, creating (or forming) a virtual model of the preform via software, and starting from (or beginning with) the virtual model of the preform, manufacturing the preform from a solid foamable polymer material are included.

[0054] In one aspect, starting from (or beginning with) an optimized virtual model, by virtually reducing (or removing) the volume (or volume or bulk) at a lower density from this optimized virtual model (however, it is stepwise), a virtual model of the preform is obtained. At this time, it is carried out until the mass of the virtual model of the generated preform (a preform of solid polymer, that is, a polymer that has not foamed) becomes equal to the mass of the optimized virtual model. That is, the volume of the virtual model of the preform becomes equal to the volume actually occupied by the polymer material of the optimized model (as if there are no bubbles as if it has not foamed).

[0055] In one aspect, the virtual model of the preform is created (or formed) by virtually compressing a plurality of regions of the optimized virtual model. However, the relative density is less than 1. It is brought to a region with a relative density equal to 1 at most.

[0056] In one aspect, the virtual model of the preform has a volume smaller than the volume of the optimized virtual model and yet has a mass equal to the mass of the optimized virtual model.

[0057] In one aspect, the foaming polymer material is selected from the group consisting of thermoplastic or thermosetting polymer materials.

[0058] In one aspect, the thermoplastic polymer material is selected from the group comprising polyolefin(s), polyurethane(s), polyester(s).

[0059] In one aspect, the thermosetting polymer material is selected from the group comprising polyurethane(s), polyester resin(s), epoxy resin(s), cyanoacrylate resin(s), polyphenol, vinyl ester(s), melamine(s), polydicyclopentadiene, and polyimide(s).

[0060] In one embodiment, step (v), which is a step of solubilizing at least one blowing agent in a foaming polymer material disposed in a mold under pressure, and using a pressure profile of at least one blowing agent that can vary based on time and / or space (or can vary with time and / or space) as a function of topology optimization, is performed according to the method shown in the publication (M. Trofa, E. Di Maio, P.L. Maffettone, "Multi-graded foams upon time-dependent exposition to blowing agent", Chemical Engineering Journal 362 (2019) 812-817). That is, it is performed according to a method comprising at least one non-equilibrium step in the mass transport of the blowing agent in the polymer using at least one condition (a condition of variability based on the time of the solubilization step before expansion).

[0061] In one embodiment, step (v) includes the following. Solubilizing a plurality of blowing agents in a foaming polymer material disposed in a mold under pressure.

[0062] In one embodiment, step (v) includes the following. Solubilizing the blowing agents one after another continuously.

[0063] In one embodiment, at least one blowing agent comprises a mixture of two or more blowing agents.

[0064] In one embodiment, at least one blowing agent is a gas.

[0065] In one embodiment, at least one blowing agent is selected from the group consisting of an inert gas and a substituted or unsubstituted aliphatic hydrocarbon (which may be linear, branched or cyclic) having 3 to 8 carbon atoms.

[0066] In one embodiment, at least one blowing agent is selected from the group consisting of nitrogen, carbon dioxide, n-butane, iso-butane, n-pentane, iso-pentane, 1,1,1,2-tetrafluoroethane (Freon R-134a), 1,1-difluoroethane (Freon R-152a), difluoromethane (Freon R-32), pentafluoroethane, and sulfur hexafluoride (or sulfur hexafluoride).

[0067] In one embodiment, the pressure profile changes periodically or aperiodically over time (or with time).

[0068] Using a pressurization program with the partial pressures of various blowing agents, different concentrations of blowing agents are solubilized in the polymer constituting the preform.

[0069] In one embodiment, the pressure profile changes from a minimum pressure (equal to atmospheric pressure) to a maximum of 300 bar. Optionally, it changes from atmospheric pressure to 250 bar. Optionally, it changes from atmospheric pressure to 200 bar.

[0070] In one embodiment, the step (vi) of releasing the pressure is performed immediately, i.e., at a rate of pressure decrease of 0.1 MPa / s to 1000 MPa / s, optionally 1 MPa / s to 10 MPa / s.

[0071] In one embodiment, in order to optimize various steps, a thermal profile is set for the polymer material during step (iv) and / or step (v) and / or step (vi).

[0072] In other words, first, during the solubilization step and immediately before pressure release, the temperature of the system (or system) is controlled in order to optimize the various steps.

[0073] In one aspect, a thermal profile can be set in conjunction with the solubilization step in order to form (or generate or create) a complex multi-gradient system (or system) of pores (or pores or pores or pores).

[0074] In one aspect, the solubilization step (v) is operated to a temperature higher than 20°C.

[0075] In one aspect, heating the mold (and thus the polymeric material) during step (iv) (insertion) and / or step (v) (solubilization) and / or step (vi) (release) is included.

[0076] In one aspect, the mold is heated according to a thermal profile (a thermal profile that can vary as needed based on time and / or space (or a thermal profile that can vary with time and / or space)).

[0077] In one aspect, the mold is heated to a temperature included between 50°C and 350°C, up to 250°C as needed.

[0078] In one aspect, cooling the mold (and thus the polymeric material) after step (vi) (release) and before step (vii) (removal) is included. This allows the foam to solidify and also stabilize the achieved multi-gradient foam structure.

[0079] In one aspect, cooling the mold before step (vi) (release) is included. By doing so, the transition is made from the temperature of solubilization of the blowing agent to the temperature of solidification / release. In one aspect, the mold is cooled to a temperature included between 5°C and 150°C, up to 100°C as needed.

[0080] In one embodiment, step (v) (solubilization) is operated for a solubilization time on the order of minutes or tens of minutes.

[0081] In one embodiment, it includes partially filling the empty volume of the mold with an incoherent material (or a non - coherent material or a non - interfering material or a non - adhering material or a non - sticky material or an incoherent material) (a foaming polymer material), in the form of grains (or granules or pellets) or spheres (or balls), if necessary.

[0082] In one embodiment, the incoherent material is the same foaming polymer material as the preform or a different material.

[0083] In one embodiment, the incoherent material has a degree of crystallinity and / or an order (or sequence or orderliness or order) of structure different from that of the preform.

[0084] In one embodiment, it includes selecting the incoherent material and its amount such that solubilization of the blowing agent in the foaming polymer material is locally restricted or prevented (or suppressed). Thus, the above - mentioned incoherent material performs the following two functions (or dual functions or double functions). Shortening the time of the solubilization step (v), and Contributing to the production (or formation or manufacture) of a product with a complex multi - gradient density

[0085] In one embodiment, partially filling the empty volume is performed after step (iv) (the step of putting (or inserting) the foaming polymer material into the mold).

[0086] In one aspect, the incoherent material spheres (or balls) or grains (or granules or granuluses) have dimensions (or diameters or sizes) on the order of millimeters (μm). Optionally, the spheres (or balls) have diameters (or diameters) included between 0.01 mm and 3 mm.

[0087] In addition to partially filling the preform into the mold, optionally, by including an incoherent material (polymer) to fill the mold in a more distant (or more separated) region (or part), the time of the solubilization step (v) can be reduced. By reducing the size (or dimension or dimension) of the spheres (or balls) / grains (or granules or granuluses), the processing time can be maintained short. By this means, the solubilization step (or step) can be shortened to the order of minutes.

[0088] In one aspect, it includes partially or entirely masking one or more parts of the preform placed in the mold. This is to locally limit or prevent (or suppress) the solubilization of at least one blowing agent in the foaming polymer material. This is an alternative means, and such means contribute to producing (or forming or manufacturing) products with complex multi-gradient densities of the polymer material.

[0089] In one aspect, partially or completely masking one or more parts of the preform includes the following. Applying (or coating) a film to a part (s) of the preform, where the film is configured to prevent (or suppress) or limit the passage of the blowing agent.

[0090] In one aspect, applying (or coating) the film includes the following. Applying (or coating) an aqueous solution of a polymer, wherein the polymer has barrier properties against a foaming agent at a part (s) of the surface of the preform. Thereby, the water (or moisture) of the solution can be evaporated (or evaporated) to obtain a film. Alternatively, evaporate (or evaporate).

[0091] In one embodiment, the product of the foamed polymer material (or foamed polymer material) does not have (or is continuous) density discontinuities. In other words, the product of the foamed polymer material (or foamed polymer material) has a density gradient (or density gradient) (which may be a high gradient). That is, the density is not constant. However, it changes gently and does not have discontinuities (or is continuous).

[0092] In one embodiment, the product can be an article / element (or component or ingredient or element) belonging to various fields. Also, it is a separate / self-standing article / element (or component or ingredient or element). Alternatively, it may be a part (or component) of a more complex assembly (or assembly).

[0093] In one embodiment, the product is a vehicle, a boat (e.g., the hull of a boat), an aircraft, a building structure (a building structure for sound insulation if necessary), clothing or fashion accessories (or accessories for clothing), a medical device (or medical apparatus or medical instrument or medical appliance), a single (or individual) protective device (or protective instrument or protective device or protective instrument or protective device or protection device) (e.g., a helmet) or a collective protective device (or collective protective device), a part of furniture (e.g., a table), a part of sports equipment, or a part of these.

[0094] Further features and advantages will be apparent from a detailed description of a preferred embodiment (but not exclusive) of a method (or process or process) for manufacturing a product of a foamed polymer material (or foamed polymer material) according to the present invention.

[0095] (Description of the Drawings) Such an explanation will be made clear in the following disclosure while referring to the accompanying drawings provided only as non-limiting examples.

Brief Description of the Drawings

[0096]

Figure 1A

Figure 1B

Figure 1C

Figure 2A

Figure 2B

Figure 2C

Figure 2D

Figure 3

Figure 4

Figure 5A

Figure 5B

Figure 5C

Figure 6

[0097] DETAILED DESCRIPTION OF EMBODIMENTS OF THE PRESENTINVENTION 1A, 1B, 1C, 2A, 2B, 2C, 2D and the flow diagram of FIG. 3 show schematic examples of methods (or treatments or processes) for producing foamed polymeric material (or foamed polymeric material) products according to the present invention. In such examples, the products shown are shown as a kind of two-dimensionally represented portal for illustrative purposes only to explain the methods (or treatments or processes) and are not intended to represent actual products.

[0098] Software calculation programs (e.g. Autodesk (登録商標) By Autocad (登録商標) or Ansys (登録商標)By means of 3D design), first, a virtual model (or virtual model) M of a product that can be manufactured is created (or formed or generated). Also, for this purpose, a foaming polymer material (or foamable polymer material) to be used is determined (or defined or specified) (Fig. 1A). For example, such a foaming polymer material is a thermoplastic polymer material (e.g., polystyrene) or a thermosetting polymer material (e.g., polyurethanes, polyester resins, epoxy resins, cyanoacrylate resins, polyphenols, vinyl esters, melamines, polydicyclopentadiene, and polyimides). The foaming polymer material of the virtual model M is solid (i.e., not porous and without air bubbles). That is, this has a dense (or compact) and non-foaming (or non-foamed) conformation (or shape or form).

[0099] Topology optimization software program (e.g., Autodesk (登録商標) by Fusion 360 or Ansys (登録商標)Once typical loads (or forces) and constraints (constraints that a product made of a foamed polymer material (or a foamed polymer material) experiences during its operating life (or operating lifetime)) are determined (or specified or defined) by Topology Optimization (which may be the same software or different software used to form the virtual model M), the mass distribution of the virtual model M is redetermined (or respecified or redefined). At this time, the same shape and the same volume (or volume) as the virtual model M are maintained. As a function of such typical loads and constraints, the topology optimization software recalculates the density of various parts (or components) of the virtual model M. By doing so, for example, the overall stiffness of the product structure is maintained, stress points exceeding the threshold of the material itself are prevented (or suppressed), and such a structure is made lighter. Usually, various optimization goals (or targets) can be input (or inserted) by this software (for example, maximizing the resistance (or tolerance or resistance) to loads and / or reducing the mass to a specific ratio (or percentage)). Through topology optimization, an optimized virtual model MO is created (or formed or generated). This optimized virtual model MO has a plurality of regions (or parts) with different relative densities. Figure 1A shows the virtual model M. This virtual model M is solid polystyrene with a uniform density. Figure 1B shows the optimized virtual model MO. In this optimized virtual model MO, a region A with a higher density and a region B with a lower density can be seen. As can be observed, the virtual model M of the product (i.e., a product that can be manufactured from a solid foaming polymer material) and the optimized virtual model MO (the one with a plurality of regions with different relative densities) have the same shape and still occupy the same volume.The relative density of the virtual model M of the product (i.e., a product that can be manufactured from a solid foaming polymer material) is equal to 1 overall (or anywhere). The relative density of region A of the optimized virtual model MO is, for example, equal to 0.9. Here, the relative density is a relative density given by the ratio of the density of the foamed polymer material having a predetermined volume to the density of the same solid polymer material having the same volume (i.e., a non-foamed material without air bubbles). The relative density of region B of the optimized virtual model MO is, for example, equal to 0.6. In FIG. 1B, for the sole purpose of clarity of description, regions A and B were clearly distinguished and illustrated. However, the method (or process or procedure) aims to avoid a sharp change in density.

[0100] At this point, in order to virtually compress regions A and B of the optimized virtual model MO, the optimized virtual model MO is always processed via software. By doing so, the relative density becomes lower than 1 (however, the relative density of these two regions is at most equal to 1), and a virtual model of the preform MP is obtained (FIG. 1C). The preform MP has a volume smaller than the volume of the optimized virtual model MO. Also, its mass is equal to the mass of the optimized virtual model MO. Also, the virtual model of the preform MP can have a shape different from that of the optimized virtual model MO.

[0101] The actual preform P is composed of a solid foaming polymer material (in the example described here, non-foamed polystyrene), starting from the virtual model of the preform MP and achieved, for example, by injection molding or other techniques.

[0102] Alternatively, start with an optimized virtual model and calculate the preform shape. Darken areas where the relative density is less than 1, leaving only (or providing or forming) areas where the relative density is equal to 1 visible. Supply (or distribute or allocate or disperse) additional material with a relative density equal to 1 to the areas where the relative density is equal to 1 as described above. When this additional material foams, it forms (or generates) areas (plural) with different relative densities (or differentiated relative densities) less than 1 in the final foamed polymer material product.

[0103] According to various options (or alternatives), starting from the optimized virtual model MO, the mass of the virtual model of the generated preform MP (solid polymer, i.e., the mass in the unfoamed state) is reduced (or removed) stepwise and virtually in volume (or volume or bulk) at a lower density from the optimized virtual model MO until it is equal to the mass of the optimized virtual model MO (i.e., the volume (or volume or bulk) of the virtual model of the preform MP is the same as the volume (or volume or bulk) actually occupied by the polymer material of the optimized model MP (as if there are no bubbles as if it is unfoamed)), to obtain a virtual model of the preform MP. The volume (or volume or bulk) and shape of the virtual model of the preform MP are derived from the optimized virtual model MO. At this time, the mass of the polymer material is maintained constant.

[0104] Next, accommodate the preform P in the chamber of the mold (or die or casting mold or form) 1 (Figure 2A). The mold 1 reproduces (or replicates) the reverse image (or reversed image) of the final shape of the product (a product that can be manufactured from the foamed polymer material).

[0105] The mold 1 is configured such that a blowing agent (e.g., a gas (e.g., N2)) can be injected into its chamber. The blowing agent is designed (or configured) to saturate the foamable polymer material of the preform P by one or more stages of solubilization under pressure. Accordingly, the mold 1 is provided with an inlet (or entrance) 2. The inlet 2 is connected to one or more pumps (e.g., a positive displacement pump). Such a pump is driven by an electronic control unit, and such an electronic control unit controls such a pump (s) and is also for operating various programs (programs for injecting the blowing agent, programs for pressure management of the blowing agent). Also, the mold 1 is provided with an outlet (or exit) 3 to enable the discharge of the blowing agent. The outlet 3 is controlled by a valve, and such a valve is connected to the control unit.

[0106] The chamber of the mold 1 has a volume (or capacity or volume) larger than the volume (or capacity or volume) of the preform P. By doing so, as seen in Figure 2A, the preform P placed in the mold 1 only partially fills the mold. Thereby, an empty volume (or void volume (or capacity or volume) or empty space) 4 is provided (or formed or left). In the schematic example shown in Figure 2A, the empty volume 4 is surrounded between the upper and lateral outer surfaces of the preform P and the lower and lateral inner surfaces of the chamber of the mold 1.

[0107] The electronic control unit is programmed as a function of the previously executed topology optimization. And this electronic control unit drives a pump. By doing so, the blowing agent is introduced into the mold 1 with one or more pressure profiles by such a pump. Here, the pressure profile can vary based on time and / or space (or can vary with time and / or space). The blowing agent is introduced into the mold 1 and acts on the foamable polymer material of the preform P. The pressure of the blowing agent is varied based on time (or with time) according to a predetermined profile. For example, the pressure profile is changed based on time (or with time) periodically or aperiodically. Further, the pressure of the blowing agent can be adjusted, and by doing so, it takes various values at various parts of the surface of the preform P. For such a purpose, for example, the mold 1 can be provided with an internal separator. The internal separator divides the chamber into sub-chambers. For example, an inlet 2 is provided in each of the sub-chambers. This is for introducing the blowing agent with each pressure profile respectively. For example, the pressure profile varies from a minimum pressure equal to atmospheric pressure to a maximum pressure of 300 bar (bar).

[0108] The foaming agent is solubilized in the foaming polymer material of the preform P. Then, various concentrations of the foaming agent are achieved in various regions of the polymer constituting the preform P. In the schematic example shown in FIG. 2B, the concentration of the foaming agent is lower in the more inner region (region A' with a greater distance from the free surface) of the preform P, while the concentration of the foaming agent is higher in the more outer region (region B' with a smaller distance from the free surface) of the preform P. In the subsequent pressure release step (or step) (here, by opening the valve at the outlet 3, almost immediate (or instantaneous) decompression of the chamber of the mold 1 becomes possible), the more outer region B' of the preform P foams more than the more inner region A'. Thereby, the product S of the foamed polymer material is formed. The product S has a plurality of regions with different relative densities as described above. The product S corresponds to the optimized virtual model MO. As can be observed, during the pressure release step (or step), the empty volume 4 is filled by the bubbles of the foamed polymer.

[0109] The pressure profile(s) of the foaming agent(s) is / are formed (or generated) by the pump(s) under the control of the control unit, starting (or departing) from the result of the previously executed topology optimization and calculated to determine the shape, dimensions, and number (number per unit volume) of the bubbles (or bubbles) formed in the foamed polymer material (to determine the morphology (or form)). And thus, determine the local density of this foamed polymer material. The foamed polymer material has a density gradient (which may be high), but has no discontinuity (or is continuous).

[0110] Next, the product (S) of the foamed polymeric material can be removed (or taken out or removed) from the mold 1 (FIG. 2D). Such a product (S) of the foamed polymeric material reflects the features (or characteristics) of the optimized virtual model MO. As can be observed, the preform P has a volume smaller than the volume of the product S of the foamed polymeric material and a shape different from the final shape of the product (S) of the foamed polymeric material.

[0111] In a variant (or variant or variant) of the method (or process or process) according to the invention, the solubilization (or dissolution or solubilization) step (or step) is carried out by using a plurality of blowing agents continuously injected into the chamber of the mold 1 or by using a mixture of blowing agents.

[0112] In a variant (or variant or variant) of the method (or process or process), the reagent (or reagent or agent) or blowing agent(s) may be selected from the group consisting of: inert gases, and substituted or unsubstituted aliphatic hydrocarbons (which may be straight-chain, branched or cyclic) having 3 to 8 carbon atoms. For example, the blowing agent may be nitrogen, carbon dioxide, n-butane, iso-butane, n-pentane, iso-pentane, 1,1,1,2-tetrafluoroethane (Freon R-134a), 1,1-difluoroethane (Freon R-152a), difluoromethane (Freon R-32), pentafluoroethane, sulfur hexafluoride (or sulfur hexafluoride).

[0113] In a variant (or variant or variant) of the method (or process or process) according to the invention, after placing the preform P in the chamber of the mold 1, in order to promote the solubilization (or dissolution or solubilization) of the blowing agent, an incoherent material (or non-coherent material or non-interfering material or non-adhering material or non-sticking material or incoherent material) of the foamable polymer material (for example, the same foamable polymer material as the preform) (for example, grains (or granules or granules) or spheres (or balls)) completely or partially filling the empty volume (or empty volume (or volume or volume) or empty volume) 4 of the mold 1. In this case, if necessary, the blowing agent is solubilized not only in the foamable polymer material of the preform P, but also in the grains / spheres of such a cooperative (or compliant) material contained in the mold. In this way, this solubilization step (or step) can be shortened to the order of several tens of minutes to several minutes. Also, such spheres (or balls) can be selected (for example, material, number and dimensions). By doing so, the solubilization of the blowing agent in the foamable polymer material will be locally restricted. Therefore, even more complex multi-gradient products can be obtained.

[0114] In a variant (or variant or variation) of the method (or process or procedure) according to the invention, in order to produce a complex product (or composite product or complex product) having a multi-gradient density of a polymeric material, one or more portions of the preform P are partially or completely masked (or covered or coated). Thereafter, the preform P is placed in the mold 1. In this way, when the preform P is placed in the mold 1, in the foaming polymeric material, the solubilization of the blowing agent can be locally restricted or prevented (or suppressed). For such purposes, for example, an aqueous solution of a polymer can be applied (or coated) (for example, polyvinyl alcohol (PVA)). By this polymer, barrier properties against a blowing agent (for example, CO2) are provided to a part (s) of the surface of the preform P. A PVA film is obtained by evaporation of water. Such a PVA film can locally condition (or condition) the step (or step) of solubilizing CO2.

[0115] In a variant (or variant or variation) of the method (or process or procedure) according to the invention, first, in order to optimize various steps (or steps), the temperature of the system (or system) is controlled during the step (or step) of solubilization (or dissolution or solubilization) and immediately before pressure release. For example, the solubilization step (v) operates (or operates or runs or operates) at a temperature higher than 20°C. Alternatively, in order to achieve a complex multi-gradient system (or system) together with the density of the polymeric material, a heat profile that can vary based on time and / or space (or a heat profile that can vary with time and / or space) can be set (or set) in relation to the solubilization step. For example, the mold 1 is heated to a temperature included between 50°C and 350°C. Also, if possible, after the step (vi) (release) and before the step (vii) (removal), for example, the mold 1 can be cooled to a temperature included between 5°C and 150°C. Thereby, the foam can be solidified and the obtained multi-gradient foam structure can be stabilized.

[0116] In a variation (or variant) of a method (or process or procedure), by controlling pressure and / or temperature and / or the type of blowing agent, a product can be produced that has an average relative density lower than 1 (i.e., lower than the relative density of the starting solid foaming polymer material), has a density gradient (or density gradient) or a morphology gradient (or morphology gradient) (where the relative density is uniform and less than 1), or has both a density gradient and a morphology gradient.

[0117] Figures 4A - 4F illustrate different examples. This is an example for forming (or manufacturing) a polystyrene stool (or chair or table) 5. Figure 4A illustrates the stool (or chair or table) that can be created (or manufactured). Figure 4B illustrates the virtual model M of the stool 5. Here, the load (or force) F applied (or exerted) on the stool 5 is depicted in a direction perpendicular to the seat of the stool 5. Figure 4C illustrates the optimized virtual model MO. Here, the regions (or parts) with darker colors represent the parts with higher density. The regions (or parts) with lighter colors indicate the parts with lower density.

[0118] Figure 4D illustrates a polystyrene preform P. This is calculated as described above and is formed by injection molding (or injection molding). As can be observed, this preform P consists of four longer legs (or feet or leg parts) 6 and four shorter arms (or arms or arm parts) 7. The four arms 7, together with the upper part (or top) of the four legs 6, are configured to form the seat 8 of the stool (before solubilization and foaming are performed). The lower part (or bottom) of the four legs 6 is configured to form the legs 9 of the stool 5.

[0119] Place (or insert or position) the preform P into the mold 1 (Fig. 4E). This mold 1 has the shape of the final tool. The preform P partially fills the mold 1. By doing so, an empty volume (or void volume (or capacity or volume) or empty space) is provided (or formed or left). Such an empty volume is filled with foam (or bubbles or foam) only by a subsequent foaming process (or foaming step). In such an empty volume, in order to maintain a short process time, it is possible to probably fill it with polystyrene spheres (or balls) (diameter = several millimeters (several mm)).

[0120] Solubilization includes a first pressurization step (or pressurization). Here, nitrogen (N2) at 100 bar (characterized by having a lower solubility in polystyrene) is used. Then, washing (or rinsing) with carbon dioxide (CO2) (characterized by having a higher solubility in polystyrene) is carried out at 100 bar. At this time, N2 is replaced by CO2. The inner region of the preform P (where the distance from the free surface is longer (or farther)) has a lower concentration of the blowing agent. The part (or portion) of the preform P exposed to the blowing agent is characterized by an increasing density profile towards its interior during subsequent foaming. Thereby, the density is lower on the outside and higher on the inside. In this example, in all steps (or stages) of the method (or treatment or process), the mold 1 is maintained at 100 °C.

[0121] Fig. 4F illustrates the tool 5, which is obtained after releasing the pressure in the mold 1 and still foaming the polystyrene. According to the optimized virtual model MO, the regions (or parts) with darker colors in the figure represent the parts with higher density. The regions (or parts) with lighter colors are the parts with lower density.

[0122] Figures 5A, 5B, 5C and 6 illustrate other examples. This is an example for forming (or manufacturing) the cap 10 of a polystyrene helmet. Figure 5A illustrates the preform P. Figure 5B illustrates the preform within the mold. Figure 5C illustrates the final product (S) of the foamed polymer material (or foamed polymeric material). As can be observed, the preform P comprises a hemispherical outer portion 11 and a plurality of excrescences 12. The plurality of excrescences 12 extend (or extend radially) in a radial direction (or radially) towards the inside of the hemispherical outer portion (or hemispherical exterior) 11. After solubilization and subsequent foaming, the plurality of excrescences 11 form the inner portion (or interior) of the cap 10. Figure 6 illustrates the optimized virtual model MO (MO of the cap). The optimized virtual model MO (MO of the cap) has a plurality of regions with different relative densities. Here, the regions (or portions) with darker colors represent the portions with higher densities. The regions (or portions) with lighter colors represent the portions with lower densities.

[0123] The products obtainable by the method (or process or procedure) according to the present invention are diverse (or multiple) and relate to various fields (or different fields). The products are, for example, vehicles, boats, aircraft, building structures (building structures for sound insulation if necessary), clothing or apparel accessories (or clothing accessories), medical devices (or medical equipment or medical instruments or medical appliances), individual (or personal) protective gear (or protective devices or protective equipment or protective instruments or protective devices or protection devices) (for example, the above-mentioned helmet) or collective protective gear (or collective protective gear), furniture (part of it) (for example, the above-mentioned small table), sports equipment (part of it), or parts of these. The disclosure of this specification may include the following aspects. (Aspect 1) A method for manufacturing a product formed from a multi-gradient foamed polymer material, comprising the following steps i to vii: Step i Creating a virtual model (M) of a product manufactured from a solid foamable polymer material via software; Step ii Applying constraints and / or loads required by the application and optimizing the topology of the virtual model (M) via software to obtain an optimized virtual model (MO) having a plurality of regions with different relative densities and / or a plurality of regions with different morphologies; Step iii Preparing the solid foamable polymer material; Step iv Placing the solid foamable polymer material into a mold (1); Step v A step of solubilizing at least one foaming agent under pressure in the solid foamable polymer material placed in the mold (1), using a pressure profile of the at least one foaming agent that can vary based on time and / or space as a function of the optimization of the topology; Step vi Releasing pressure to manufacture a product (S) formed from a foamed polymer material having a plurality of regions with different relative densities and / or a plurality of regions with different morphologies; and Step vii Removing the product (S) of the foamed polymer material from the mold (1) A method comprising the above steps. (Aspect 2) The method according to Aspect 1, wherein Step iii includes manufacturing a preform (P) from the solid foamable polymer material, and Step iv includes placing the preform (P) in the mold (1). (Aspect 3) The method according to Aspect 2, wherein, prior to at least Step v, the preform (P) placed in the mold (1) partially fills the mold (1) to provide an empty volume (4) to enable expansion of the solid foamable polymer material during Step vi. (Aspect 4) Creating, via software, a virtual model of the preform (MP) from the optimized virtual model (MO), and manufacturing the preform (P) from the virtual model of the preform (MP), the method according to embodiment 2 or 3. (Embodiment 5) (Embodiment 4) The virtual model of the preform (MP), obtained from a solid polymer, i.e., from a non-foamed polymer, is created from the optimized virtual model (MO) by virtually reducing the volume at a lower density stepwise until the mass of the virtual model of the preform (MP) becomes equal to the mass of the optimized virtual model (MO). (Embodiment 6) (Any one of Embodiments 2 - 5) The manufacturing of the preform (P) includes shaping the preform, optionally including injection molding or compression molding, and manufacturing the preform by blow molding or rotational molding. (Embodiment 7) (Any one of Embodiments 3 - 7, provided that for Embodiments 4 and 6, when they are dependent on Embodiment 3) Partially filling the empty volume (4) of the mold (1) with an incoherent material of the same foamable polymer material, optionally in the form of grains or spheres, to promote solubilization. (Embodiment 8) (Any one of Embodiments 2 - 7) Masking part or all of the preform (P) disposed in the mold (1) to locally limit or prevent solubilization of the at least one blowing agent in the foamable polymer material. (Embodiment 9) (Embodiment 8) Masking part or all of the preform (P) includes applying a film to the corresponding part of the preform (P). (Embodiment 10) (Embodiment 7) Selecting the incoherent material and its amount in such a way as to locally limit or prevent solubilization of the blowing agent in the foamable polymer material. (Embodiment 11) During step iv and / or step v and / or step vi, heating the mold (1) optionally based on a thermal profile. Cooling the mold (1) before and / or after step vi and before step vii as necessary The method according to any one of aspects 1 to 10, comprising: (Aspect 12) The method according to any one of aspects 1 to 11, wherein the pressure profile changes periodically or aperiodically over time (Aspect 13) The method according to any one of aspects 1 to 12, wherein the pressure profile varies from a minimum pressure equal to atmospheric pressure to a maximum of 300 bar, optionally from atmospheric pressure to 250 bar, and optionally from atmospheric pressure to 200 bar (Aspect 14) The method according to any one of aspects 1 to 13, wherein step v comprises solubilizing a plurality of blowing agents under pressure in the foamable polymer material disposed in the mold (1), and optionally sequentially and continuously solubilizing the blowing agents (Aspect 15) The method according to any one of aspects 1 to 14, wherein at least one blowing agent is selected from the group consisting of a gas, optionally nitrogen and / or carbon dioxide, and a substituted or unsubstituted aliphatic hydrocarbon (which may be linear, branched or cyclic) having 3 to 8 carbon atoms (Aspect 16) The method according to any one of aspects 1 to 15, wherein the foamable polymer material is selected from the group consisting of a thermoplastic or thermosetting polymer material (Aspect 17) The method according to any one of aspects 1 to 16, wherein step v of solubilizing under pressure comprises introducing the blowing agent under pressure into the mold (1) containing the foamable polymer material, and when the pressure of the blowing agent is released after saturating the foamable polymer material with the blowing agent, the foamable polymer material foams (Aspect 18) The product (S) formed from the foamed polymer material is a vehicle, a boat, an aircraft, a building structure (optionally a soundproof building structure), clothing or a clothing accessory, a medical device, an individual protective gear or a collective protective gear, furniture, a sports item, or a part thereof, and is formed from a foamed polymer material manufactured according to the method according to at least one of aspects 1 to 17

Claims

1. A method for manufacturing a product formed from a multi-gradient foamed polymer material, comprising the following steps i to vii: Step i: Creating a virtual model (M) of a product manufactured from a solid foamable polymer material via software; Step ii: Applying constraints and / or loads required by the application and optimizing the topology of the virtual model (M) via software to obtain an optimized virtual model (MO) having a plurality of regions with different relative densities and / or a plurality of regions with different morphologies; Step iii: Preparing the solid foamable polymer material; Step iv: Placing the solid foamable polymer material into a mold (1); Step v: A step of solubilizing at least one blowing agent under pressure in the solid foamable polymer material placed in the mold (1), using a pressure profile of the at least one blowing agent that can vary based on time and / or space as a function of the topology optimization; Step vi: Releasing pressure to produce a product (S) formed from a foamed polymer material having a plurality of regions with different relative densities and / or a plurality of regions with different morphologies; and Step vii: Removing the product (S) of the foamed polymer material from the mold (1). A method comprising the above steps.

2. The method according to claim 1, wherein step iii includes manufacturing a preform (P) from the solid foamable polymer material, and step iv includes placing the preform (P) in the mold (1).

3. The method according to claim 2, wherein, prior to at least step v, the preform (P) placed in the mold (1) partially fills the mold (1) to provide an empty volume (4) so that the solid foamable polymer material can expand during step vi.

4. The method according to claim 2 or 3, comprising creating a virtual model of the preform (MP) from the optimized virtual model (MO) via software, and manufacturing the preform (P) from the virtual model of the preform (MP).

5. The virtual model of the preform (MP), obtained from a solid polymer, i.e., an unfoamed polymer, is created by virtually reducing the volume at a lower density, step by step, from the optimized virtual model (MO), until the mass of the virtual model of the preform (MP) equals the mass of the optimized virtual model (MO), according to the method of claim 4.

6. The method according to any one of claims 2 to 5, wherein the production of the preform (P) includes forming the preform and includes manufacturing the preform by blow molding or rotational molding.

7. The method according to any one of claims 3 to 6 (provided that for claims 4 and 6, when they are dependent on claim 3), including partially filling the empty volume (4) of the mold (1) with an incoherent material of the same foaming polymer material to promote solubilization.

8. The method according to any one of claims 2 to 7, including masking part or all of the preform (P) disposed in the mold (1) to locally limit or prevent solubilization of the at least one blowing agent in the foaming polymer material.

9. The method according to claim 8, wherein masking part or all of the preform (P) includes applying a film to the corresponding part of the preform (P).

10. The method according to claim 7, including selecting the incoherent material and its amount in such a way as to locally limit or prevent solubilization of the blowing agent in the foaming polymer material.

11. The method according to any one of claims 1 to 10, including heating the mold (1) during step iv and / or step v and / or step vi.

12. The method according to any one of claims 1 to 11, including cooling the mold (1) before and / or after step vi and before step vii.

13. The method according to any one of claims 1 to 12, wherein the pressure profile changes periodically or non-periodically based on time.

14. The method according to any one of claims 1 to 13, wherein the pressure profile varies from a minimum pressure equal to atmospheric pressure to a maximum of 300 bar.

15. The method according to any one of claims 1 to 14, wherein step v comprises solubilizing a plurality of blowing agents in the foamable polymer material disposed in the mold (1) under pressure.

16. The method according to any one of claims 1 to 15, wherein at least one blowing agent is selected from the group consisting of gases selected from nitrogen and carbon dioxide, and substituted or unsubstituted aliphatic hydrocarbons having 3 to 8 carbon atoms.

17. The method according to any one of claims 1 to 16, wherein the foamable polymer material is selected from the group consisting of thermoplastic or thermosetting polymer materials.

18. The method according to any one of claims 1 to 17, wherein the step v of solubilizing under pressure comprises introducing the blowing agent under pressure in the mold (1) containing the foamable polymer material, and when the pressure of the blowing agent is released after the blowing agent saturates the foamable polymer material, the foamable polymer material foams.

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