Preparation method of gradient porous foam structure

Abstract

The invention discloses a preparation method of a gradient porous foam structure, which comprises the following steps: a printing layer is arranged, a liquid forming material is laid on the printing layer, and the forming material is an acousto-optic sensitive material and comprises thermosetting resin and a photosensitizer; forming a pore structure in the printing layer through optical path curing and / or acoustic cavitation; continuous printing layers are sequentially arranged, a continuous pore structure is formed, and the multiple printing layers form a gradient porous foam structure. The gradient porous foam structure in the forms of multi-stage aperture, multi-stage porosity, gradient aperture, gradient porosity, combination of ordered pores and disordered pores and the like is formed in the printing layer through the photocuring and / or acoustic cavitation effect, space continuous forming is achieved, assembling is not needed, and the gradient porous foam structure has the advantages of being easy to operate, high in forming efficiency, high in forming precision and the like.

Description

Technical Field

[0001] The invention relates to the technical field of continuous molding of porous structures, and in particular to a method for preparing a gradient porous foam structure. Background Art

[0002] Porous foam structures refer to the introduction of pores into bulk materials to achieve the desired performance requirements. In particular, porous polymers have attracted widespread attention due to their potential to combine the properties of porous structures and polymer materials. Compared with non-porous materials, the advantages of porous polymers include their large surface area, easy control and processing of the desired porosity, etc. In recent decades, porous foam structures have been widely used in greenhouse gas adsorption, proton conduction, flexible conductors, energy storage and conversion, adsorption and separation, catalysis, drug delivery and release, biomedical scaffolds, and tissue engineering.

[0003] The gradient porous foam structure has a pore structure distributed according to a certain porosity and pore size pattern. Existing preparation methods include template leaching, emulsion template, phase separation, gas foaming, 3D printing and other technologies. Existing preparation methods can only prepare pore structures with a single microstructure feature, and cannot achieve gradient porous foam structures with different porosities and pore size distributions. For example, when the porous foam structure is required to have a multi-level void structure, a gradient pore size, a regular arrangement and distribution of large pores (>50μm) and small pores (<50μm), a combination of regular pore geometry and irregular pore geometry, and other customized microstructures, the existing preparation methods cannot meet such complex requirements, and it is necessary to seek new preparation methods to achieve the continuous preparation of porous foam structures. Summary of the invention

[0004] The present invention aims to solve at least one of the problems in the related art to a certain extent. To this end, one of the purposes of the present invention is to provide a method for preparing a gradient porous foam structure, which forms a gradient porous foam structure in the form of multi-level pore size, multi-level porosity, gradient pore size, gradient porosity, a combination of ordered pores and disordered pores in a printed layer through optical path curing and / or acoustic wave cavitation, and is spatially continuously formed without assembly, and has the advantages of simple operation, high forming efficiency, and high forming precision.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme: a method for preparing a gradient porous foam structure, comprising:

[0006] Providing a printing layer, wherein the printing layer is paved with a liquid molding material, wherein the molding material includes a thermosetting resin and a photosensitizer;

[0007] Forming a porous structure in the printed layer by optical curing and / or acoustic cavitation;

[0008] Continuous printing layers are arranged in sequence to form a continuous pore structure, and several printing layers form a gradient porous foam structure.

[0009] Furthermore, the light path curing includes: setting the light beam route so that the molding material is solidified at the position where the light beam is irradiated; and the molding material remains in liquid state at the position where the light beam is not irradiated.

[0010] Furthermore, the acoustic wave cavitation includes: partially solidifying the molding material to form a pore structure by regulating the power and frequency of the acoustic wave.

[0011] Furthermore, when the acoustic wave frequency f≦1.6MHz, the pore size range of the pore structure formed by acoustic cavitation is 60-80um;

[0012] When 1.6MHz<sound wave frequency f≦2MHz, the pore size range of the pore structure formed by acoustic cavitation is 42-60um;

[0013] When 2MHz<sound wave frequency f≦2.5MHz, the pore size range of the pore structure formed by acoustic cavitation is 25-42um;

[0014] When 2.5MHz<sound wave frequency f≦3MHz, the pore size range of the pore structure formed by acoustic cavitation is 15-25um;

[0015] When the sound wave frequency f>3MHz, the pore size range of the pore structure formed by acoustic cavitation is 0-15um.

[0016] Furthermore, when the acoustic wave power w≦20W, the pore size range of the pore structure formed by acoustic cavitation is 0-1um, and the porosity of the pore structure is 0%-1%;

[0017] When 20W<sound wave power w≦40W, the pore size range of the pore structure formed by acoustic cavitation is 1-40um, and the porosity of the pore structure is 5%-15%;

[0018] When 40W<sonic wave power w≦100W, the pore size range of the pore structure formed by acoustic cavitation is 40-80um, and the porosity of the pore structure is 10%-30%.

[0019] Furthermore, in the same printing layer, the first region forms a first pore structure through optical path solidification, and the second region forms a second pore structure through acoustic wave cavitation.

[0020] Furthermore, in the same printing layer, a first pore structure is formed by optical path curing; and a second pore structure is formed by acoustic cavitation of the molding material in the first pore structure, and the pore size of the second pore structure is smaller than that of the first pore structure.

[0021] Furthermore, the thermosetting resin comprises a free radical prepolymer, a curing agent, a plasticizer and a toughening agent; and the mass ratio of the free radical prepolymer: the curing agent: the plasticizer: the toughening agent: the photosensitizer is 14:1:1:1:1;

[0022] The mass fraction of the photosensitizer is 1wt%-10wt%;

[0023] The molding material further includes a filler, the weight fraction of the filler is 0wt%-5wt%; the filler includes a metal filler or a ceramic filler.

[0024] Further, when the filler weight fraction is ≦5wt%, the porosity of the pore structure formed by acoustic cavitation is 5%-35%;

[0025] When 5wt%<filler weight fraction≦10wt%, the porosity of the pore structure formed by acoustic cavitation is 1%-5%.

[0026] Furthermore, for the molding material in the printing layer, before performing optical path curing and / or acoustic cavitation, the method further includes: degassing the molding material, when the degassing pressure is ≦0.07MPa, the porosity of the pore structure formed by the acoustic cavitation is 1%-5%;

[0027] When 0.07MPa<degassing pressure≦0.1MPa, the porosity of the pore structure formed by acoustic cavitation is 0-1%.

[0028] The present application provides a method for preparing a gradient porous foam structure, wherein printing layers are arranged layer by layer, and each printing layer is paved with a liquid molding material, wherein the molding material is an acoustic-optical sensitive material, specifically including a thermosetting resin and a photosensitizer; a pore structure is formed in the printing layer by optical path curing and / or acoustic wave cavitation. The present application arranges continuous printing layers in sequence, and cures the molding material of each layer. During the curing process, the pore structure is controlled by the path of the optical path or the acoustic wave parameters, so that a continuous pore structure can be formed, and several printing layers are finally stacked to form a gradient porous foam structure. In the final formed gradient porous foam structure, adjacent printing layers are continuous and the corresponding pore structures are continuous. By printing layer by layer, a gradient porous foam structure with a microstructure in the form of multi-level pore size, multi-level porosity, gradient pore size, gradient porosity, a combination of ordered pores and disordered pores, etc. can be prepared at one time, and no subsequent assembly process is required. The present application can achieve one-time production of a gradient porous foam structure with a variety of microstructural features by adjusting different curing methods and parameters for each layer of molding material, and has the advantages of simple operation, high efficiency, high precision and low cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the invention and, together with the description, serve to explain the principles of the invention.

[0030] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0031] In the attached figure:

[0032] Figure 1 It is a schematic diagram of the composition of the molding material;

[0033] Figure 2 Schematic diagram of the preparation process of the continuous gradient pore size foam structure in Example 1;

[0034] Figure 3 Schematic diagram of the preparation process of the gradient porous foam structure with continuous multi-level porosity in Example 2;

[0035] Figure 4 Schematic diagram of the preparation process of the customized porous foam structure in Example 3;

[0036] Figure 5 Schematic diagram of the preparation process of the cylindrical porous foam structure with a transparent outer shell and a multi-level porous inner core in Example 4.

[0037] Figure numbers: 1. Light source transmitter; 2. Sound wave transducer. DETAILED DESCRIPTION

[0038] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, the specific embodiments of the present invention are now described in detail with reference to the accompanying drawings. In the following description, it should be understood that the directions or positional relationships indicated by "front", "back", "up", "down", "left", "right", "longitudinal", "horizontal", "vertical", "horizontal", "top", "bottom", "inside", "outside", "head", "tail", etc. are based on the directions or positional relationships shown in the accompanying drawings, are constructed and operated in a specific direction, and are only for the convenience of describing the present technical solution, rather than indicating that the mechanism or element referred to must have a specific direction, and therefore cannot be understood as a limitation to the present invention.

[0039] It should also be noted that, unless otherwise clearly specified and limited, the terms such as "installed", "connected", "connected", "fixed", "set" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. When an element is referred to as being "on" or "under" another element, the element can be "directly" or "indirectly" located on the other element, or there may be one or more intermediate elements. The terms "first", "second", "third", etc. are only for the convenience of describing the present technical solution, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first", "second", "third", etc. can explicitly or implicitly include one or more of the features. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to the specific circumstances.

[0040] In the following description, specific details such as specific system structures, technologies, etc. are provided for the purpose of illustration rather than limitation, so as to provide a thorough understanding of the embodiments of the present invention. However, it should be clear to those skilled in the art that the present invention may be implemented in other embodiments without these specific details. In other cases, detailed descriptions of well-known systems, mechanisms, circuits, and methods are omitted to prevent unnecessary details from obstructing the description of the present invention.

[0041] The present application provides a method for preparing a gradient porous foam structure, comprising:

[0042] Providing a printing layer, wherein the printing layer is paved with a liquid molding material, wherein the molding material includes a thermosetting resin and a photosensitizer;

[0043] Forming a porous structure in the printed layer by optical curing and / or acoustic cavitation;

[0044] Continuous printing layers are arranged in sequence to form a continuous pore structure, and several printing layers form a gradient porous foam structure.

[0045] The present application provides a method for preparing a gradient porous foam structure, in which printing layers are arranged layer by layer, and each printing layer is paved with a liquid molding material, wherein the molding material includes a thermosetting resin and a photosensitizer; a pore structure is formed in the printing layer by optical path curing and / or acoustic wave cavitation. The present application arranges continuous printing layers in sequence, and cures the molding material of each layer. During the curing process, the pore structure is controlled by the path of the optical path or the acoustic wave parameters, so that a continuous pore structure can be formed, and several printing layers are finally stacked to form a gradient porous foam structure. In the present application, gradient porosity refers to that the porosity and pore size distribution of the void structure in several printing layers are not completely the same, and the porosity and pore size distribution of the void structure between adjacent printing layers can change in the form of continuous change, gradual change or sudden change, thereby forming a gradient porous foam structure.

[0046] In the final gradient porous foam structure, adjacent printed layers are continuous and the corresponding pore structures are continuous. By printing layer by layer, a gradient porous foam structure with microstructures in the form of multi-level pore size, multi-level porosity, gradient pore size, gradient porosity, and a combination of ordered and disordered pores can be prepared at one time without the need for a subsequent assembly process. This application can achieve one-time production of a gradient porous foam structure with a variety of microstructure characteristics by adjusting different curing methods and parameters for each layer of molding material, with the advantages of simple operation, high efficiency, high precision, and low cost.

[0047] The molding material in the present application includes a thermosetting resin and a photosensitizer. The photosensitizer makes the molding material suitable for photocuring molding, and the thermosetting resin makes the molding material suitable for acoustic wave curing molding. Therefore, when the molding material is used to prepare a gradient porous foam structure, the microstructure can be regulated by photocuring parameters and acoustic wave parameters.

[0048] Specifically, the light path curing includes: setting the light beam route so that the molding material is solidified at the position where the light beam is irradiated; and the molding material remains in a liquid state at the position where the light beam is not irradiated.

[0049] The 3D printed porous foam structure based on light energy is manufactured by irradiating the molding material with ultraviolet light or other special light sources, causing the molding material to undergo a series of physical and chemical reactions and then solidify and mold. Optical path curing technology can be applied to various microscopic manufacturing and processing scenarios to form a continuous gradient porous foam structure by printing a network layer by layer. The present application can control the scanning path of the light beam in the form of SLA (stereolithography) or control the projection image of the light beam in the form of DLP (digital light processing), thereby preparing highly ordered and precise microstructure features.

[0050] In the microstructure of the gradient porous foam structure in this application, the pores with a diameter greater than 50μm are called macropores; the pores with a diameter less than or equal to 50μm are called small pores. The pore characteristics of the macropores can be jointly regulated by the printing layer height, the beam scanning path (SLA) or the projection image design (DLP). Specifically, the printing layer height parameter settings include but are not limited to 50μm, 75μm, 100μm, 200μm, and the beam scanning molding path or the beam projection image can be set to include but are not limited to a single-layer grid containing pores of 50μm, 75μm, 100μm, 200μm, etc. Further, the pore geometries such as circular, rectangular, honeycomb, and special-shaped can be regulated by the beam scanning molding path or the beam projection image design, that is, the light speed scanning path is set according to the pore shape to ensure that the molding material is solidified at the position where the beam is scanned, and the molding material at the position where the beam is not scanned remains in liquid form and can be removed later. At the same time, the pore characteristics such as porosity and pore distribution can be accurately set by the beam scanning molding path or the beam projection image. Therefore, the pore characteristics of the macropores in the microstructure of the gradient porous foam structure can be regulated by the photocuring parameters.

[0051] Acoustic cavitation in this application includes: by regulating the power and frequency of the acoustic wave, the molding material is solidified and a pore structure is formed in the solidified part. Specifically, the acoustic wave can act on thermosetting resins such as PDMS-based resins, acrylate-based resins, and epoxy resins, so that the thermosetting resins react and solidify under the mechanical, physical, and chemical composite effects of the acoustic wave to achieve direct acoustic manufacturing, which can be used for the processing and manufacturing of macro structures, and can achieve cross-scale multi-degree-of-freedom manufacturing. In particular, in the area where the sonochemical reaction occurs, there are micropores caused by the mechanical and physical effects of the implosion of cavitation bubbles. The microstructure produced in this way has a pore geometry that is nearly circular, and the pore size distribution range can be controlled within 0-80μm, especially within 50μm. Therefore, in this application, the small holes are formed by acoustic cavitation. The porosity, pore size range, etc. formed by acoustic cavitation can be controlled by adjusting acoustic wave parameters, such as acoustic wave frequency and acoustic wave power.

[0052] Under the mechanical, physical and chemical combined effects of sound waves, the pore structure of small holes is formed by the sound wave cavitation bubble effect. The degree of the sound wave cavitation bubble effect can affect the characteristics of the pores. Regulating the sound wave power can change the porosity and pore size distribution range. The greater the sound wave power, the more intense the cavitation bubble effect, the larger the porosity formed, and the larger the pore size distribution range. The porosity and pore size distribution range can be changed by regulating the sound wave frequency. Compared with high frequency, low frequency leads to a larger pore size range, while high frequency leads to a narrower pore size range.

[0053] Specifically, experiments have shown that in the process of forming small holes, when the acoustic wave frequency is used to control the pore formation, when the acoustic wave frequency f≦1.6MHz, the pore size range of the pore structure formed by acoustic wave cavitation is 60-80um; when 1.6MHz<acoustic wave frequency f≦2MHz, the pore size range of the pore structure formed by acoustic wave cavitation is 42-60um; when 2MHz<acoustic wave frequency f≦2.5MHz, the pore size range of the pore structure formed by acoustic wave cavitation is 25-42um; when 2.5MHz<acoustic wave frequency f≦3MHz, the pore size range of the pore structure formed by acoustic wave cavitation is 15-25um; when the acoustic wave frequency f>3MHz, the pore size range of the pore structure formed by acoustic wave cavitation is 0-15um.

[0054] Specifically, experiments have shown that in the process of forming small holes, when the acoustic wave power is used to control the pore formation, when the acoustic wave power w≦20W, the pore size range of the pore structure formed by acoustic cavitation is 0-1um, and the porosity of the pore structure is 0%-1%; when 20W<acoustic wave power w≦40W, the pore size range of the pore structure formed by acoustic cavitation is 1-40um, and the porosity of the pore structure is 5%-15%; when 40W<acoustic wave power w≦100W, the pore size range of the pore structure formed by acoustic cavitation is 40-80um, and the porosity of the pore structure is 10%-30%.

[0055] like Figure 1 As shown, the molding material of the present application is a raw photosensitive material, that is, the molding material can be cured under the action of sound waves and can also be photocured. Specifically, the molding material includes a thermosetting resin and a photosensitizer. Among them, the thermosetting resin includes a free radical prepolymer, a curing agent, a plasticizer and a toughening agent; and the mass ratio of free radical prepolymer: curing agent: plasticizer: toughening agent: photosensitizer is 14:1:1:1:1. The free radical prepolymer in the main component includes but is not limited to PDMS-based resin, acrylate-based resin, epoxy resin, etc. The photosensitizer is a photoinitiator, which can be azobisisobutyronitrile, etc., and the mass fraction of the photosensitizer in the molding material is 1wt%-10wt%. The curing agent can be 2-ethyl-4-methylimidazole, etc., and the weight percentage in the molding material is 5%-25%. The toughening agent can be polyurethane, etc., and the weight percentage in the molding material is within 5%; the plasticizer can be dioctyl phthalate, etc., and the weight percentage in the molding material is within 5%. The molding material in the present application may also include fillers, which are additives and have a weight percentage of 0wt%-5wt% in the molding material; the fillers may be metal fillers, ceramic fillers, diamonds or glass fibers, etc. Metal fillers may include iron powder, etc., and ceramic fillers may include Al 2 O 3 wait.

[0056] In the process of forming small holes by acoustic cavitation, in addition to adjusting the pores by acoustic frequency and acoustic power, the pore parameters can also be adjusted by adjusting the filler content and the degassing pressure of the molding material. Specifically, when adding fillers to prepare molding materials, the fillers can fill the pores to a certain extent. With the appropriate increase in the content of the filling particles, the pore size and porosity will decrease.

[0057] Furthermore, based on the acoustic cavitation bubble effect, degassing the molding material before the acoustic wave can reduce the degree of cavitation effect and achieve the function of regulating pore characteristics. By regulating the degassing pressure during the vacuum defoaming process, the porosity and pore size distribution range during the acoustic cavitation process can be regulated.

[0058] When the filler weight fraction is ≦5wt%, the porosity of the pore structure formed by acoustic cavitation is 5%-35%; when 5wt%<filler weight fraction≦10wt%, the porosity of the pore structure formed by acoustic cavitation is 1%-5%.

[0059] For the molding material in the printing layer, before performing optical path curing and / or acoustic cavitation, it also includes: degassing the molding material, when the degassing pressure is ≦0.07MPa, the porosity of the pore structure formed by the acoustic cavitation is 1%-5%; when 0.07MPa<degassing pressure≦0.1MPa, the porosity of the pore structure formed by the acoustic cavitation is 0-1%.

[0060] In the present application, in the same printed layer, the first area forms a first pore structure through optical path curing, and the second area forms a second pore structure through acoustic wave cavitation. In other words, for the same printed layer, large pores can be formed partially through optical path curing, and large pores can be formed partially through acoustic wave cavitation, thereby forming a large pore structure and a small pore structure in the same printed layer.

[0061] In the present application, in the same printing layer, a first pore structure is formed by optical path curing; in the first pore structure, the molding material remains in liquid state and is not cured in places not irradiated by the light beam. A second pore structure is formed by acoustic wave cavitation for the liquid molding material in the first pore structure, and the pore size of the second pore structure is smaller than that of the first pore structure. In other words, a large pore is formed by optical path curing, and acoustic wave cavitation is performed again for the uncured molding material inside the large pore, so that the molding material inside the large pore is partially cured, and small pores are formed by acoustic wave cavitation, thereby forming a pore structure in which large pores are nested with small pores.

[0062] In this application, light path curing and acoustic cavitation can be used simultaneously or selectively in the same printing layer, can be used locally or globally, and can also be used in a nested manner. Through the coordination of light path curing and acoustic cavitation, a gradient porous foam structure with more complex pore characteristics is achieved, including but not limited to forming a continuous multi-level pore size foam structure, a continuous gradient pore size foam structure, a continuous multi-level porosity foam structure, a continuous gradient porosity foam structure, and the like. The following is a further explanation and description of this application through specific embodiments:

[0063] Example 1

[0064] like Figure 2 As shown, a method for preparing a gradient porous foam structure is used to prepare a continuous gradient pore size foam structure, comprising:

[0065] S1: preparing a molding material, the molding material comprising a thermosetting resin and a photosensitizer, wherein the thermosetting resin comprises a PDMS-based resin, a curing agent, a plasticizer and a toughening agent; and the mass ratio of the PDMS-based resin: curing agent: plasticizer: toughening agent: photosensitizer is 14:1:1:1:1; the mass fraction of the photosensitizer is 1wt%-10wt%.

[0066] S2: The prepared molding material is subjected to a degassing treatment at a degassing pressure of 0.07 MPa.

[0067] S3: Setting the thickness of the first printing layer to 100 μm, the printing layer is paved with liquid molding material; setting the control parameters of the light source emitter 1 so that the beam forming path is set to a grid containing 100 μm×100 μm pores, and curing the first printing layer by the action of the light beam.

[0068] S4: The lifting work platform moves down a distance of a printing layer thickness to the second printing layer, and the control parameters of the light source emitter 1 are set so that the molding path is set to the column of the array, and the second printing layer is processed and solidified by the light beam.

[0069] S5: Move the workbench down by a printing layer thickness to the third printing layer, and repeat steps S3 and S4 until the desired thickness of the pore structure is reached.

[0070] S6: Move the workbench down by a printing layer thickness, set the printing layer thickness to 50 μm, set the control parameters of the light source emitter 1 so that the beam forming path is set to a grid containing 50 μm×50 μm pores, similar to steps S3-S5, to prepare a pore structure with a pore size of 50 μm.

[0071] S7: Replace the light source emitter 1 with the acoustic wave transducer 2, set the acoustic wave power to 100 W, the acoustic wave frequency to 45 kHz, and complete the preparation of a pore structure with a pore size distribution range of less than 50 μm of the required thickness through layer-by-layer solidification.

[0072] S8: The remaining molding material is subjected to a degassing treatment with a degassing pressure of 0.1 MPa to form a subsequent printing layer.

[0073] S9: Setting the parameters of the acoustic wave transducer 2, wherein the acoustic wave power is 40 W and the acoustic wave frequency is 1.5 MHz, and preparing a part of the material with a smaller pore size distribution range, a smaller porosity or even no pores inside the pore structure in step S7 through layer-by-layer solidification.

[0074] S10: taking out the structure on the working plate for subsequent processing and cleaning the residual liquid material, thereby completing the preparation of a porous foam material with a microstructure having a gradient pore size ranging from 100 μm to almost no pores.

[0075] Example 2

[0076] like Figure 3 As shown, a method for preparing a gradient porous foam structure is used to prepare a gradient porous foam structure with continuous multi-level porosity, comprising:

[0077] S1: preparing a molding material, the molding material comprising a thermosetting resin and a photosensitizer, wherein the thermosetting resin comprises an acrylate-based resin, a curing agent, a plasticizer and a toughening agent; and the mass ratio of the acrylate-based resin: curing agent: plasticizer: toughening agent: photosensitizer is 14:1:1:1:1; the mass fraction of the photosensitizer is 1wt%-10wt%.

[0078] S2: The prepared molding material is subjected to a degassing treatment at a degassing pressure of 0.07 MPa.

[0079] S3: setting the thickness of the first printing layer to 50 μm, and the printing layer is paved with liquid molding material; setting the control parameters of the light source emitter 1 so that the light beam forming path is set to a grid containing 50 μm×50 μm pores, and curing the first printing layer by the action of the light beam.

[0080] S4: The lifting work platform moves down a distance of a printing layer thickness to the second printing layer, and the control parameters of the light source emitter 1 are set so that the molding path is set to the column of the array, and the second printing layer is processed and solidified by the light beam.

[0081] S5: Move the workbench down by a printing layer thickness to the third printing layer, and repeat steps S3 and S4 until the desired thickness of the pore structure is reached.

[0082] S6: Move the workbench down by a printing layer thickness, set the printing layer thickness to 50μm, set the control parameters of the light source emitter 1, so that the beam forming path is set to a grid containing 50μm×50μm pores, and process and solidify the printing layer through the action of the beam to form large holes; set the acoustic power of the acoustic transducer 2 to 40W and the acoustic frequency to 45KHz, and use the acoustic cavitation action on the uncured molding material inside the local large holes in the printing layer to form small holes inside the large holes. A pore structure with a pore size of 50μm is prepared by multi-layer printing and solidification.

[0083] S7: Move the workbench down by a print layer thickness, set the print layer thickness to 50μm, set the control parameters of the light source emitter 1, so that the beam forming path is set to a grid containing 50μm×50μm pores, and process and solidify the print layer through the beam to form large pores; set the acoustic power of the acoustic transducer 2 to 40W and the acoustic frequency to 1.0MHz, and use the acoustic cavitation to act on the uncured molding material inside the local large pores in the print layer to form small pores inside the large pores, and the porosity and pore size distribution range of the small pores formed here are smaller than those formed in step S6. A pore structure with a pore size of 50μm is prepared by multi-layer printing and solidification.

[0084] S8: Move the workbench down by a print layer thickness, set the print layer thickness to 50μm, set the control parameters of the light source emitter 1, so that the beam forming path is set to a grid containing 50μm×50μm pores, and process and solidify the print layer through the action of the beam to form large pores; set the acoustic power of the acoustic transducer 2 to 100W and the acoustic frequency to 45KHz, and use the acoustic cavitation to act on the uncured molding material inside the local large pores in the print layer to form small pores inside the large pores, and the porosity and pore size distribution range of the small pores formed here are larger than those formed in step S6. A pore structure with a pore size of 50μm is prepared by multi-layer printing and curing.

[0085] S9: taking out the structure on the working plate for subsequent processing and cleaning the residual liquid material, thereby completing the preparation of a gradient porous foam structure with continuous multi-level porosity.

[0086] Example 3

[0087] like Figure 4 As shown, a method for preparing a gradient porous foam structure is used to prepare a customized porous foam structure, comprising:

[0088] S1: preparing a molding material, the molding material comprising a thermosetting resin and a photosensitizer, wherein the thermosetting resin comprises an epoxy resin, a curing agent, a plasticizer and a toughening agent; and the mass ratio of epoxy resin: curing agent: plasticizer: toughening agent: photosensitizer is 14:1:1:1:1; the mass fraction of the photosensitizer is 1wt%-10wt%.

[0089] S2: The prepared molding material is subjected to a degassing treatment at a degassing pressure of 0.07 MPa.

[0090] S3: Set the thickness of the first printing layer to 200 μm, and the printing layer is paved with liquid molding material; set the control parameters of the light source emitter 1 so that the light beam projection image is designed to be a honeycomb structure composed of regular hexagons with a side length of 150 μm, and solidify the first printing layer through light source projection to form a regular hexagonal honeycomb structure.

[0091] S4: Setting the parameters of the acoustic wave transducer 2, wherein the acoustic wave power is 40 W, the acoustic wave frequency is 60 kHz, and performing acoustic wave cavitation on the uncured molding material inside the honeycomb structure in step S3, and the range of the acoustic wave cavitation is the triangular ring at the center of the first printing layer, so that the molding material in the honeycomb pore structure inside the triangular ring is cured, and small holes are formed inside the honeycomb pore structure.

[0092] S5: Set the parameters of the acoustic transducer 2, wherein the acoustic power is 100 W and the acoustic frequency is 35 kHz, and perform acoustic cavitation on the unsolidified molding material inside the honeycomb structure in the central area of ​​the triangular ring in step S4, and the range of the acoustic cavitation is the central area of ​​the triangular ring (not overlapping with the small holes in step S4), so that the molding material in the honeycomb pore structure in the central area of ​​the triangular ring is solidified, and small holes are formed inside the honeycomb pore structure, and the porosity of the small holes here is greater than the porosity of the small holes inside the triangular ring area in step S4.

[0093] S6: Repeat steps S3-S5 to form a porous structure of desired thickness through multi-layer printing.

[0094] S7: Take out the structure on the working plate for subsequent processing and clean the residual liquid material to complete the preparation of the customized porous foam structure.

[0095] Example 4

[0096] like Figure 5 As shown, a method for preparing a gradient porous foam structure is used to prepare a cylindrical porous foam structure having a transparent shell and a multi-level porous core, comprising:

[0097] S1: preparing a molding material, the molding material comprising a thermosetting resin and a photosensitizer, wherein the thermosetting resin comprises a PDMS-based resin, a curing agent, a plasticizer and a toughening agent; and the mass ratio of the PDMS-based resin: curing agent: plasticizer: toughening agent: photosensitizer is 14:1:1:1:1; the mass fraction of the photosensitizer is 1wt%-10wt%.

[0098] S2: The prepared molding material is subjected to a degassing treatment at a degassing pressure of 0.07 MPa.

[0099] S3: Set the thickness of the first printing layer to 200 μm, and the printing layer is paved with liquid molding material; set the control parameters of the light source emitter 1 so that the light beam forming path is set to a grid containing 200 μm×200 μm pores, and solidify layer by layer to the required thickness through light source projection, forming a cylindrical foam structure with a transparent shell and a porous core.

[0100] S4: Setting the parameters of the acoustic transducer 2 so that the acoustic power is 100 W and the acoustic frequency is 35 kHz, utilizing the penetrability of the acoustic wave, outside the cylinder obtained in step S3, by adjusting the focal length of the acoustic wave, solidifying the unsolidified molding material in the cylindrical grid layer by layer from the bottom of the cylinder to the top in a circular manner, and forming a first small hole in the grid in step S3, the aperture of the first small hole being smaller than the aperture of the inner core hole obtained in step S3.

[0101] S5: Setting the parameters of the acoustic transducer 2 so that the acoustic power is 100 W and the acoustic frequency is 1.0 MHz, utilizing the penetrability of acoustic waves, outside the cylinder obtained in step S3, by adjusting the focal length of the acoustic waves, solidify the unsolidified molding material in the cylindrical grid layer by layer from the bottom of the cylinder to the top in a circular manner, and form a second small hole in the grid in step S3, and the porosity of the aperture of the second small hole is smaller than the porosity of the first small hole.

[0102] S6: taking out the structure on the working plate for subsequent processing and cleaning the residual liquid material, completing the preparation of the gradient porous foam structure with a transparent outer shell and a multi-level pore core.

[0103] This application combines the photocuring 3D printing porous technology and the cavitation effect of sound waves on thermosetting materials, and is used to prepare porous foam materials from thermosetting photosensitive materials. It makes full use of the advantages of photocuring 3D printing technology, such as highly controllable, precisely ordered pore characteristics, and large pore (>50μm) preparation, and the advantages of sound waves, such as non-contact, penetrable, focusable, and small pore (<50μm) preparation, to achieve more complex microstructures, thereby obtaining multifunctional porous foam materials and expanding their application range.

[0104] It can be understood that the above embodiments only express the preferred implementation modes of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the patent scope of the present invention. It should be pointed out that, for ordinary technicians in this field, the above technical features can be freely combined without departing from the concept of the present invention, and several deformations and improvements can be made, which all belong to the protection scope of the present invention. Therefore, all equivalent changes and modifications made to the scope of the claims of the present invention should belong to the coverage of the claims of the present invention.

Claims

1. A method for preparing a gradient porous foam structure, characterized in that: include: Providing a printing layer, wherein the printing layer is paved with a liquid molding material, wherein the molding material includes a thermosetting resin and a photosensitizer; Forming a porous structure in the printed layer by optical curing and / or acoustic cavitation; Continuous printing layers are arranged in sequence to form a continuous pore structure, and several printing layers form a gradient porous foam structure.

2. The method for preparing a gradient porous foam structure according to claim 1, characterized in that: The light path curing includes: setting the light beam route so that the molding material is cured at the position where the light beam is irradiated, and the molding material remains in a liquid state at the position where the light beam is not irradiated.

3. The method for preparing a gradient porous foam structure according to claim 1, characterized in that: The acoustic wave cavitation includes: partially solidifying the molding material to form a pore structure by regulating the power and frequency of the acoustic wave.

4. The method for preparing a gradient porous foam structure according to claim 1, characterized in that: When the sound wave frequency f≦1.6MHz, the pore size range of the pore structure formed by acoustic cavitation is 60-80um; When 1.6MHz<sound wave frequency f≦2MHz, the pore size range of the pore structure formed by acoustic cavitation is 42-60um; When 2MHz<sound wave frequency f≦2.5MHz, the pore size range of the pore structure formed by acoustic cavitation is 25-42um; When 2.5MHz<sound wave frequency f≦3MHz, the pore size range of the pore structure formed by acoustic cavitation is 15-25um; When the sound wave frequency f>3MHz, the pore size range of the pore structure formed by acoustic cavitation is 0-15um.

5. The method for preparing a gradient porous foam structure according to claim 1, characterized in that: When the acoustic wave power w≦20W, the pore size range of the pore structure formed by acoustic cavitation is 0-1um, and the porosity of the pore structure is 0%-1%; When 20W<sound wave power w≦40W, the pore size range of the pore structure formed by acoustic cavitation is 1-40um, and the porosity of the pore structure is 5%-15%; When 40W<sonic wave power w≦100W, the pore size range of the pore structure formed by acoustic cavitation is 40-80um, and the porosity of the pore structure is 10%-30%.

6. The method for preparing a gradient porous foam structure according to claim 1, characterized in that: In the same printing layer, the first area forms a first pore structure through optical path solidification, and the second area forms a second pore structure through acoustic wave cavitation.

7. The method for preparing a gradient porous foam structure according to claim 1, characterized in that: In the same printing layer, a first pore structure is formed by optical path curing; and a second pore structure is formed by acoustic wave cavitation for the molding material in the first pore structure, and the pore size of the second pore structure is smaller than that of the first pore structure.

8. The method for preparing a gradient porous foam structure according to claim 1, characterized in that: The thermosetting resin comprises a free radical prepolymer, a curing agent, a plasticizer and a toughening agent; and the mass ratio of the free radical prepolymer: the curing agent: the plasticizer: the toughening agent: the photosensitizer is 14:1:1:1:1; The mass fraction of the photosensitizer is 1wt%-10wt%; The molding material further includes a filler, the weight fraction of the filler is 0wt%-5wt%; the filler includes a metal filler or a ceramic filler.

9. The method for preparing a gradient porous foam structure according to claim 8, characterized in that: When the filler weight fraction is ≦5wt%, the porosity of the pore structure formed by acoustic cavitation is 5%-35%; When 5wt%<filler weight fraction≦10wt%, the porosity of the pore structure formed by acoustic cavitation is 1%-5%.

10. The method for preparing a gradient porous foam structure according to claim 1, characterized in that: For the molding material in the printing layer, before performing optical path curing and / or acoustic cavitation, the method further includes: degassing the molding material, when the degassing pressure is ≦0.07MPa, the porosity of the pore structure formed by the acoustic cavitation is 1%-5%; When 0.07MPa<degassing pressure≦0.1MPa, the porosity of the pore structure formed by acoustic cavitation is 0-1%.

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