Foaming type dual-curing additive manufacturing method and additive manufacturing resin elastomer capable of being obtained through foaming type dual-curing additive manufacturing method

Abstract

The present disclosure provides a method of additive manufacturing of a foamed dual cured resin and an additive manufactured resin elastomer that may be formed therefrom. The method includes the following operations. A resin providing procedure: providing a foaming type dual-curing resin composition suitable for continuous liquid interface production additive manufacturing; an additive manufacturing procedure: placing the foaming type dual-curing resin composition in a printer table for continuous liquid interface production, irradiating the foaming type dual-curing resin composition with a digital UV light source, and carrying out photopolymerization on the irradiated foaming type dual-curing resin composition part to define a grid structure so as to form an intermediate with a three-dimensional grid; and a foaming procedure: placing the intermediate with the three-dimensional grid in a heating environment, foaming the intermediate, and thermally curing the intermediate to further enhance the performance of the intermediate so as to form the additive manufacturing resin elastomer. The additive manufacturing resin elastomer is fully cured, has high volume foaming rate and uniform density, and does not cause deformation of a three-dimensional network defined by additive manufacturing due to foaming.

Description

Technical Field

[0001] This disclosure relates to a method for additively manufacturing a foamable dual-cure resin and an additively manufactured resin elastomer formed thereby. Specifically, the disclosure relates to a method for additively manufacturing a foamable dual-cure resin for use in continuous liquid interface production (CLIP) 3D printing technology and the resulting additively manufactured resin elastomer. Background Art

[0002] Continuous liquid interface production (CLIP) 3D printing technology utilizes UV light projected onto a transparent resin feed tank. Upon exposure to UV light, the liquid dual-cure resin composition within the tank undergoes cross-linking and polymerization, forming a three-dimensional structure. This three-dimensional structure is then heated, causing the blocked polyurethane in the dual-cure resin composition to deblock and rearrange, ultimately curing, resulting in a molded resin product. Details of the CLIP technology can be found on Carbon3D's website at https: / / www.carbon3d.com / carbon-dls-technology. While the continuous liquid interface design allows for more detailed and sophisticated structures than conventional layer-by-layer 3D printing, placing the liquid dual-cure resin composition within the resin feed tank also limits the size of the printed object. Therefore, Carbon3D has further developed a foamable resin composition that allows the CLIP technology to initially print a smaller three-dimensional structure, which is then cured and foamed during heating, ultimately resulting in a finished product that is not limited by the size of the resin feed tank in the CLIP printer bed.

[0003] The foamable resin composition developed by Carbon3D utilizes a physical foaming process for microcapsules. This involves mixing hollow spherical particles containing a thermoplastic resin shell and a lower alkane content with a base resin (also known as a dual-cure resin composition) to create the foamable dual-cure resin composition. When the foamable dual-cure resin composition is printed in a CLIP printer, the microcapsules and the base resin are exposed to UV light. As the base resin undergoes a cross-linking polymerization reaction to form a three-dimensional structure, the microcapsules embedded within it become embedded within the solid portion of the three-dimensional structure. Because the microcapsules expand in volume due to the vaporization of the lower alkane content, the thermoplastic resin shell softens and expands upon heating, still able to encapsulate the vaporized alkane content. Compared to established chemical foaming processes, this process is more environmentally friendly and does not suffer from the expensive equipment and safety risks associated with other physical foaming processes, such as those using supercritical fluids.

[0004] However, although Carbon3D disclosed in its patent publication number US11292186B2 the additive manufacturing technology of using foaming resin compositions to manufacture low-density three-dimensional objects, it did not further explore how the process should be controlled to obtain a uniformly foamed final product when heat-expandable microspheres are added to the dual-cured resin. In addition, patent publication number WO2023078844A1 proposes a shoe midsole with dual shock-absorbing effects of foaming material and three-dimensional network structure for conventional foamed shoe midsoles. However, the technical means adopted is to achieve the desired cushioning effect through the spatial geometry of the three-dimensional network and the foaming rate of the foaming agent. It does not specify the physical foaming technology used, nor does it involve specific foaming processes and foaming uniformity. Therefore, the relevant literature does not clearly teach how to manufacture an additively manufactured resin elastomer that has both an additively manufactured three-dimensional network structure and a foamed material property in the solid structure of the grid structure, so as to ensure that the formed additively manufactured resin elastomer can still maintain the integrity of the additively manufactured three-dimensional network during the foaming process. Summary of the Invention

[0005] The present disclosure provides a method for additive manufacturing of a foamable dual-cure resin. The method includes the following operations. A resin providing procedure is performed, including providing a foamable dual-cure resin composition, wherein the foamable dual-cure resin composition includes a base resin and thermally expandable microcapsules. An additive manufacturing procedure is performed, including placing the foamable dual-cure resin composition in a printer station for continuous liquid interface production, causing the base resin irradiated with ultraviolet light to undergo photopolymerization reaction to form a solid part, thereby defining a plurality of grid structures, wherein: the grid structure collection constitutes a three-dimensional network, and the three-dimensional network constitutes an intermediate; and the thermally expandable microcapsules in the foamable dual-cure resin composition are embedded in the solid part of the grid structure of the intermediate as the base resin in the foamable dual-cure resin composition undergoes photopolymerization reaction. The foaming process includes removing the intermediate from the continuous liquid interface printer and placing it in a heated environment. The thermally expandable microcapsules embedded in the solid portion of the lattice structure expand upon heating, thereby expanding the three-dimensional network of the intermediate due to the expansion of the thermally expandable microcapsules and subsequently expanding the overall volume of the intermediate until the final foaming is achieved. The intermediate is then heated in the heated environment to achieve thermal curing, ultimately forming an additive manufacturing resin elastomer. In some embodiments, the lattice structure includes a solid portion and a space enclosed by the solid portion.

[0006] In some embodiments, the resin providing process provides a foamable dual-cure resin composition that exhibits minimal sedimentation based on Stokes' law. For example, the resin formulation may have the following characteristics: a small density difference between the thermally expandable microcapsules and the base resin, an appropriate base resin viscosity, and an appropriate particle size. Stokes' law is expressed as follows:

[0007]

[0008] In some embodiments, the density difference between the base resin and the thermally expandable microcapsules in the foamable dual-cure resin composition is less than 1 g / mL and greater than or equal to 0 g / mL.

[0009] In some embodiments, the thermally expandable microcapsules do not react to ultraviolet light exposure during additive manufacturing.

[0010] In some embodiments, the foaming process includes a heating process and a constant temperature process. The heating process includes heating from room temperature to 90°C to 220°C at a rate of 1°C to 3.5°C per minute. The constant temperature process includes continuing heating at the final temperature reached by the heating process after the heating process is completed and performing it for 1 hour to 5 hours.

[0011] In some embodiments, the foaming process includes sequentially performing a first temperature rising process, a first constant temperature process, a second temperature rising process, and a second constant temperature process, wherein the first temperature rising process is heating from room temperature to a first temperature of 100°C to 120°C in 0.75 hours to 1.25 hours, the first constant temperature process is continuously heated at the first temperature for 3.5 hours to 4.5 hours, the second temperature rising process is increasing from the first temperature to a second temperature of 130°C to 150°C in 20 minutes to 40 minutes, the second constant temperature process is performed when the second temperature is reached, and the second constant temperature process is continuously heated at the second temperature for 5 minutes to 15 minutes.

[0012] In some embodiments, the foaming process is performed at standard atmospheric pressure.

[0013] In some embodiments, the foaming process includes the polymer network formed by ultraviolet polymerization in the intermediate, and further polymer bonding occurs due to the action of thermal energy, thereby enhancing the mechanical properties of the polymer network.

[0014] The present disclosure also provides an additively manufactured resin elastomer produced by the above-described method for additively manufacturing a foamed dual-cure resin, comprising a three-dimensional network formed by additive manufacturing, the three-dimensional network being composed of interconnected lattice structures, each of which comprises a spatial arrangement of basic geometric shapes formed by a solid portion, and the three-dimensional network formed by the lattice structures constituting the solid portion of the additively manufactured resin elastomer; and the solid portion having a plurality of foamed pores therein, the absolute value of the density gradient of the additively manufactured resin elastomer in a first direction, the absolute value of the density gradient in a second direction, and the absolute value of the density gradient in a third direction being less than 50 kg / (m 3 *cm), and the first direction, the second direction and the third direction are perpendicular to each other.

[0015] In some embodiments, each of the foamed cells is a closed-cell cell.

[0016] In some embodiments, the foamed pores expand the volume of the additive manufacturing resin elastomer by 100% to 350% compared to the volume before foaming. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] When reading the drawings accompanying this disclosure, it is recommended that you consider the following to understand various aspects of this disclosure. It should be noted that, in accordance with standard industry practice, various feature dimensions may not be drawn to scale. Furthermore, for clarity of discussion, various feature dimensions may be arbitrarily increased or decreased. Furthermore, to simplify the drawings, conventional structures and components may be depicted in simplified schematic form.

[0018] Figure 1 is a flow chart of a method for additive manufacturing of foamable dual-cure resins according to some embodiments of the present disclosure;

[0019] Figure 2 Schematic diagram of a UV irradiation step according to some embodiments of the present disclosure, wherein a resin raw material tank in a continuous liquid interface production printer station is subjected to UV irradiation to photopolymerize a base resin in the resin raw material tank to form an intermediate;

[0020] Figure 3 This is a schematic diagram of a UV irradiation step according to some embodiments of the present disclosure, wherein a resin raw material tank in a continuous liquid interface production printer station is subjected to UV irradiation to photopolymerize the base resin in the resin raw material tank to form an intermediate. Figure 3 Presented in black and white and equivalent to Figure 2 An enlarged schematic diagram of the dotted box in FIG.

[0021] Figure 4A and Figure 4B is a schematic diagram of thermally curing an intermediate and causing the volume of the thermally expandable capsules therein to expand during a foaming process according to some embodiments of the present disclosure;

[0022] Figure 5A and Figure 5B is a schematic diagram of thermally curing an intermediate and causing the volume of the thermally expandable capsules therein to expand during a foaming process according to some embodiments of the present disclosure;

[0023] Figure 6 Schematic diagrams of additively manufactured resin elastomers formed according to some embodiments of the present disclosure; the left figure shows an additively manufactured resin elastomer obtained by additively manufacturing a foamed dual-cure resin; the right figure shows an additively manufactured resin elastomer obtained by additively manufacturing a non-foamed dual-cure resin;

[0024] Figure 7 Schematic diagrams of additively manufactured resin elastomers formed according to some embodiments of the present disclosure; the left figure shows a failure to properly control the foaming process, resulting in excessive foaming of the thermally expandable microcapsules and destruction of the three-dimensional network of the additively manufactured resin elastomer; the right figure shows an additively manufactured resin elastomer obtained when the foaming process is properly controlled;

[0025] Figure 8 is a schematic diagram of an additively manufactured resin elastomer formed according to some embodiments of the present disclosure, wherein the additively manufactured resin elastomer includes a plurality of portions continuously distributed from one side to an opposite side;

[0026] Figure 9 1 is a graph showing average density variations of multiple parts of an additively manufactured resin elastomer formed according to some embodiments of the present disclosure.

[0027]

Explanation of symbols

[0028] 1~15: Position

[0029] 100: Method

[0030] 101~103: Steps

[0031] 201: Digital UV light source

[0032] 202: Digital UV light irradiation range

[0033] 2021: Digital UV light focused irradiation area

[0034] 2022: Digital UV light with unfocused irradiation area

[0035] 205: Foaming dual-curing resin composition

[0036] 206: Resin raw material tank

[0037] 207:Carrier Platform

[0038] C: Intermediate

[0039] D: Pulling direction

[0040] L: Grid structure

[0041] S, S', S": entity part

[0042] B: Thermally expandable microcapsules

[0043] F in :resistance

[0044] F out :momentum DETAILED DESCRIPTION

[0045] To provide a more detailed and complete description of the present disclosure, the following description provides illustrative examples of embodiments. This does not limit the present disclosure to a single embodiment. The embodiments of the present disclosure may be combined or substituted with one another where beneficial, and additional embodiments may be included without further explanation.

[0046] Spatially relative terms, such as above and below, may be used throughout this disclosure to describe the relationship of one element to another element in the figures. In addition to the orientation depicted in the figures, spatially relative terms are intended to encompass different orientations of the device during use or operation. For example, the device may be oriented in other ways (e.g., rotated 90 degrees or in other orientations), and therefore, the spatially relative terms of this disclosure should be interpreted accordingly. Throughout this disclosure, unless otherwise indicated, identical element numbers across different figures refer to identical or similar elements formed from identical or similar materials by identical or similar methods.

[0047] The terms "about," "approximately," "close to," "substantially," or "substantially" used in this disclosure include the values ​​and features and the deviation ranges of the values ​​and features that are understood by those skilled in the art. For example, taking into account the errors of the values ​​and features, these terms may indicate values ​​within one or more standard deviations of the values ​​(e.g., values ​​within ±30%, ±20%, ±15%, ±10%, or ±5%), or indicate the deviations encompassed by the features in practical operation (e.g., the statement "substantially parallel" may indicate close to parallelism in practice rather than perfect parallelism in ideal).

[0048] The present disclosure provides a method for additive manufacturing of foamable dual-cure resins, such as Figure 1 The method 100 is shown. Figure 1 Method 100 can be referred to Figures 2 to 9 . In detail, method 100 includes steps 101 to 103. Step 101: A resin providing procedure, comprising providing a foamable dual-cure resin composition suitable for continuous liquid interface production additive manufacturing, such as a product purchased from Carbon3D or TPK Electronic Materials (such as the foamable resin composition disclosed in the patent application filed by TPK Electronic Materials with the invention name "Foamable Resin Composition and Resin Molded Product"), or a commercially available non-foamable dual-cure resin and a thermal expansion capsule purchased separately and mixed. The difference between the density of the selected non-foamable dual-cure resin and the density of the thermal expansion capsule is less than 1 g / mL. The foamable dual-cure resin composition can be obtained by the method disclosed herein, which is lighter than the unfoamed dual-cure resin composition (such as Figure 6 As shown on the right) the volume of the additive manufacturing resin elastomer is larger (such as Figure 6(shown on the left). Step 102: An additive manufacturing process, including pouring the liquid foamable dual-cure resin composition from the resin supply process of step 101 into the resin raw material tank of the continuous liquid interface production printer station, irradiating it with a digital UV light source, and causing the irradiated resin composition to undergo photopolymerization to define a grid structure, thereby forming an intermediate with a three-dimensional network. As the resin composition is polymerized by UV light irradiation, the thermally expandable microcapsules mixed in the resin composition are embedded in the solid portion of the grid structure of the intermediate. During this process, the thermally expandable microcapsules do not react to UV light irradiation. Step 103: A foaming process, including causing the thermally expandable microcapsules embedded in the solid portion of the three-dimensional structure of the intermediate to expand due to heat. Due to the action of thermal energy, the grid structure of the intermediate formed by photopolymerization is further strengthened. The additively manufactured resin elastomer can obtain a high volume foaming rate after step 103, and the grid structure additively manufactured in step 102 is not damaged due to the foaming process, that is, the grid structure in the additively manufactured resin elastomer is complete, and the solid structure formed by curing the resin composition has a spatial arrangement with a basic geometric shape that is essentially the same as the configuration of the corresponding grid structure in the intermediate before heating. In addition, step 103 allows the solid structure formed by curing the resin composition to be further thermally cured after being polymerized by UV light (step 102), so the mechanical properties of the additively manufactured resin elastomer are also significantly improved, such as improved compressive strength, torsional stiffness, shear strength, impact resistance, tensile strength, elongation at break, and (trouser-shaped) tear strength. Next, method 100 is described in detail according to the embodiment.

[0049] In step 101, when the resin is provided using a commercially available foamable dual-cure resin composition, since the foamable dual-cure resin composition comprises a liquid base resin and thermally expandable microcapsules suspended therein, the foamable dual-cure resin composition is stirred before being poured into the resin raw material tank to ensure that the thermally expandable microcapsules are evenly distributed throughout the liquid foamable dual-cure resin composition. This is because, although the shelf life and storage environment of commercially available foamable dual-cure resin compositions are considered before shipment, long-term storage can still cause the thermally expandable microcapsules to settle or float, resulting in uneven suspension and distribution of the thermally expandable microcapsules within the liquid base resin. The stirring should be sufficient to ensure that the thermally expandable microcapsules are evenly suspended within the liquid base resin, without excessively vigorous stirring to prevent shear thickening of the fluid, which could increase the overall viscosity and affect the printing quality during additive manufacturing in step 102. In step 101, when the resin is provided by purchasing a commercially available non-foamable dual-cure resin composition and thermally expandable microcapsules separately and mixing them, in addition to selecting thermally expandable microcapsules with a density close to that of the base resin, it is also important to select thermally expandable microcapsules with a relatively uniform particle size distribution (PSD). Furthermore, when purchasing the base resin and thermally expandable microcapsules separately and mixing them, the thermally expandable microcapsule particles should be moistened with a small amount of photopolymerizable monomer before adding them to the base resin to prevent the dry thermally expandable microcapsule particles from agglomerating during addition to the liquid base resin, making them difficult to evenly disperse. The photopolymerizable monomer can be the photopolymerizable monomer described in the aforementioned patent application "Foamable Resin Composition and Resin Molded Article," or other monomers capable of participating in UV photopolymerization reactions.

[0050] Continuing with step 101, the foamable dual-cure resin composition 205 includes a base resin and thermally expandable microcapsules. The base resin composition may include polyurethane (meth)acrylate and a photoinitiator. Examples include EPU40, EPU41, EPU44, and EPU46 resins manufactured by Carbon3D. Their chemical compositions are as disclosed in the patents filed and other references cited therein, such as US Pat. No. 10471655, US Pat. No. 10259171, US Pat. No. 10975193, and US Pat. No. 10350823. The difference in density between the base resin and the thermally expandable microcapsules is less than 1 g / mL and greater than or equal to 0 g / mL. Preferably, it is less than 0.5 g / mL. More preferably, it is less than 0.3 g / mL. When the density difference between the base resin and the thermally expandable microcapsules is within the aforementioned range, significant sedimentation differences between the base resin and the thermally expandable microcapsules in the foamable dual-cure resin composition 205 can be avoided. This allows the thermally expandable microcapsules to be evenly distributed when embedded in the solid portion of the grid structure during the subsequent additive manufacturing process in step 102. Consequently, the additively manufactured resin elastomer formed by foaming these evenly distributed thermally expandable microcapsules in step 103 can also achieve uniform expansion in all dimensions, i.e., achieving substantially uniform expansion in all X, Y, and Z directions, resulting in the desired density uniformity and density variation in the resulting additively manufactured resin elastomer. In some embodiments, the density of the base resin and the density of the thermally expandable microcapsules are each independently between 0.4 g / mL and 1.8 g / mL, for example, 0.4 g / mL, 0.8 g / mL, 1.0 g / mL, 1.1 g / mL, 1.2 g / mL, 1.5 g / mL, or 1.8 g / mL.

[0051] Continuing with step 101, in some embodiments, the particle size of the thermally expandable microcapsules is preferably 10 μm to 30 μm, such as 10 μm, 15 μm, 20 μm, 25 μm, or 30 μm, to prevent the thermally expandable microcapsules from settling too quickly or too slowly in the foamable dual-cure resin composition 205, thereby helping to improve the uniformity of the distribution of the thermally expandable microcapsules in the foamable dual-cure resin composition 205. In some embodiments, the viscosity of the foamable dual-cure resin composition 205 is preferably 100 cP to 10,000 cP, such as 100 cP, 500 cP, 1,000 cP, 3,000 cP, 4,000 cP, 5,000 cP, 5,500 cP, 6,000 cP, 7,000 cP, 8,000 cP, or 10,000 cP, as measured by a viscometer at approximately 25° C., with 100 cP to 5,500 cP being more preferred, to prevent the thermally expandable microcapsules from settling too quickly or too slowly in the foamable dual-cure resin composition 205, thereby helping to improve the uniformity of distribution of the thermally expandable microcapsules in the foamable dual-cure resin composition 205.

[0052] In step 102, a digital UV light source 201 focuses the light within a digital UV irradiation range 202 on the desired cross-linking region to irradiate the liquid foamable dual-cure resin composition 205 in the resin raw material tank 206, causing the base resin therein to undergo a cross-linking reaction to form an intermediate C. The digital UV light source 201 can convert a digital signal into a light focusing region having a corresponding pattern using a device based on digital light processing (DLP) technology (not shown). This allows the foamable dual-cure resin composition 205 irradiated by the digital UV light source 201 to be polymerized into the desired three-dimensional structure as desired. The DLP device used can be a 3D printer platform manufactured by Carbon3D, such as the Carbon 3D printer, including models such as M1, M2, M3, and L1, or other printer platforms designed based on the same or similar principles. In detail, a digital UV light source 201 is provided below the resin raw material tank 206. The resin raw material tank 206 has a transparent bottom, so that the light emitted by the digital UV light source 201 can pass through the bottom to irradiate the foamable dual-cure resin composition contained therein. The light emitted by the digital UV light source 201 is focused on a specific part of the resin raw material tank according to the irradiation area and irradiation time determined by the digital light signal, so that the base resin in the digital UV light focused irradiation area 2021 absorbs UV irradiation energy and undergoes photopolymerization, thereby transforming from the original liquid state to a solid state. The area where the digital UV light source 201 does not focus irradiate is called the digital UV light unfocused irradiation area 2022. Since the foamable dual-cure resin composition 205 contains a liquid base resin and thermally expandable microcapsules evenly suspended therein, and the thermally expandable microcapsules therein do not react to UV light irradiation, when the liquid base resin is polymerized to form a solid state due to UV light radiation, the thermally expandable microcapsules B originally mixed therein are thus embedded in the cured base resin, as shown in FIG. Figure 5A As the foamable dual-cure resin composition 205 loaded in the resin raw material tank 206 is additively manufactured in the 3D printer to form an intermediate body C having a three-dimensional network, the base resin in the foamable dual-cure resin composition 205 forms the solid portion S of the grid structure L in the three-dimensional network, and the thermally expandable microcapsules in the foamable dual-cure resin composition 205 are embedded in the solid portion S of the grid structure L in their original state ( Figure 3 not shown).

[0053] Continuing with step 102, in some embodiments, the digital UV light focused irradiation area 2021 is located near the bottom of the resin material tank 206. More specifically, the digital UV light source 201 is focused on a plane parallel to the bottom of the resin material tank 206, that is, the digital UV light focused irradiation area 2021 is entirely located on the same plane. For example, the digital UV light source 201 is focused on a plane parallel to the bottom of the resin material tank 206 to form a digital UV light focused irradiation area 2021 with a desired pattern, as shown in FIG. Figure 3As shown. In some embodiments, after the foamable dual-cure resin composition 205 is poured into the resin raw material tank 206, the carrier platform 207 is placed near the bottom of the resin raw material tank 206, and the digital UV light source 201 is focused on the plane of the carrier platform 207 facing the resin raw material tank 206, and a digital UV light focused irradiation area 2021 with a desired pattern is formed on the plane to form a solid portion S' of the photopolymerized solid grid structure L on the carrier platform 207. Since the UV light source is focused only on one plane, after the solid portion S' is formed on the plane of the carrier platform 207 facing the bottom surface of the resin raw material tank, the 3D printer table will move the carrier platform in the pulling direction D according to a predetermined printing program, so that the photopolymerized solid portion S' leaves the original focusing plane, and then the digital UV light source 201 again radiates focused UV light according to the digital signal to form a new solid portion S' in the direction opposite to the pulling direction D of the solid portion S'. The solid portion S' formed before the carrier platform is pulled and the carrier The new solid portion S" formed after the platform is stretched is polymerized by subjecting the liquid foamable dual-cure resin composition 205 to focused UV light irradiation. Therefore, the solid portion S' before stretching and the new solid portion S" added after stretching are continuous and have no obvious boundary. In addition, since the foamable dual-cure resin composition 205 contains a base resin and thermally expandable microcapsules, and the thermally expandable microcapsules are uniformly suspended in the base resin, when the base resin in the foamable dual-cure resin composition 205 is irradiated with focused UV light, the base resin is polymerized. When the intermediate C is combined, the heat-expandable microcapsules originally evenly suspended therein are also embedded in the solid part S formed by the base resin. That is, after the intermediate C is formed, the heat-expandable microcapsules are evenly dispersed in the solid part S of the grid structure in its three-dimensional grid. These heat-expandable microcapsules evenly distributed in the solid part S of the grid structure of the three-dimensional network exist in the original form. The so-called original form means that these microcapsules still maintain the same form as before step 102 after going through step 102. In other words, the heat-expandable microcapsules do not change during the process of step 102, especially do not undergo changes due to thermal expansion. After the aforementioned 3D printer station completes the intermediate C with a three-dimensional network by digital UV light printing according to a predetermined additive manufacturing procedure, the foaming process of step 103 is then carried out, including: removing the intermediate C from the 3D printer station and placing it in a heating environment, so that the heat-expandable microcapsules embedded in the solid part S of its grid structure L are heated and expanded, so that the three-dimensional network of the intermediate is enlarged by the expansion of the microcapsules, so that the overall volume expands and finally the foaming is completed, for example Figure 4A and Figure 4B The black and white photographs show the volume changes before and after the foaming process, respectively. Figure 4A Intermediates before foaming and Figure 4BThe final foamed product is shown on the same scale. Under the influence of the thermal energy from the foaming process, the intermediate also undergoes thermal curing. This means that the polymer network formed by UV photopolymerization undergoes denser polymer bonds due to the thermal energy, further strengthening the mechanical strength of the solid portion of the lattice structure formed by the base resin, ultimately forming an additive manufacturing resin elastomer. In some embodiments, the thermal curing and expansion step in the foaming process in step 103 includes a heating process, which includes slowly increasing the temperature at a rate of 1°C to 3.5°C per minute. In some embodiments, the heating process includes slowly increasing the temperature from room temperature to a temperature between 90°C and 220°C. In some embodiments, the thermal curing and expansion step includes a constant temperature process, which includes heating at a constant temperature between 90°C and 220°C. In some embodiments, the constant temperature process is performed for 1 to 5 hours. In some embodiments, the intermediate C can be heated at a rate of 1°C to 3.5°C per minute. For example, the temperature can be slowly increased by increasing 1°C, 1.2°C, 1.4°C, 1.5°C, 1.6°C, 1.8°C, 2°C, 2.5°C, 3°C or 3.5°C per minute. In some embodiments, the constant temperature process includes heating the intermediate C at a constant temperature of 90°C to 220°C, such as 90°C, 110°C, 115°C, 125°C, 150°C, 165°C, 170°C, 190°C or 220°C, preferably 100°C to 170°C, and more preferably 105°C to 150°C. In some embodiments, the execution time of the constant temperature process is preferably 1 hour to 5 hours, such as 1 hour, 2 hours, 3 hours, 4 hours or 5 hours. In some embodiments, the foaming procedure in step 103 includes a temperature rising process and a constant temperature process, and the constant temperature process is performed after the temperature rising process. In some embodiments, the final temperature raised from room temperature in the temperature rising process is equal to the temperature used in the constant temperature process. In some embodiments, room temperature includes 20°C to 30°C, such as 20°C, 22.5°C, 25°C, 27.5°C, or 30°C.

[0054] Continue to explain step 103. In some embodiments, the thermal curing expansion step in the step 103 foaming process includes multiple stages of heating processes and constant temperature processes. For example, it may include a first heating process, followed by a first constant temperature process. After the first constant temperature process is performed for a period of time, a second heating process is continued, and then a second constant temperature process is performed. In some embodiments, the step 103 foaming process includes a first heating process of heating the intermediate C from room temperature to 110°C in 1 hour, followed by a first constant temperature process of heating at a constant temperature of 110°C for 4 hours; after completing the first heating process and the first constant temperature process, the second heating process is then performed, which is to increase the thermal environment from 110°C to 140°C in 30 minutes, and when the thermal environment reaches 140°C, the second constant temperature process is performed, that is, the intermediate C is continuously heated at a temperature of 140°C for 10 minutes. In some embodiments, the intermediate C can be heated at a rate of 1°C to 3.5°C per minute. Preferably, the temperature is slowly increased by 1°C to 2°C per minute; more preferably, by 1°C to 1.6°C per minute. In some embodiments, the second temperature increase process has a flatter temperature increase curve than the first temperature increase process, that is, the temperature is increased by a smaller temperature increase per minute in the second temperature increase process. In some embodiments, the first constant temperature process is performed for a longer time than the second constant temperature process.

[0055] Continuing with step 103, the aforementioned constant temperature process and / or elevated temperature process facilitates aligning the expansion rate of the thermally expandable microcapsules with the thermal curing rate of the surrounding base resin, enabling the intermediate C to achieve complete foaming as much as possible. Complete foaming refers to the full expansion of the thermally expandable microcapsules embedded within the solid portion S of the three-dimensional lattice structure L of the intermediate C. Specifically, the low-carbon alkane liquid encapsulated within the thermally expandable microcapsules is fully converted to gas. The volume change caused by the liquid-to-gas conversion causes the outer shell of the thermally expandable microcapsules to expand outward, resulting in a plurality of pores embedded in the solid portion S. When the expansion rate of the thermally expandable microcapsules matches the thermal curing rate of the base resin (which, after UV photopolymerization, forms the solid portion S of the lattice structure L), the shells of the thermally expandable microcapsules remain intact when fully expanded. That is, after the foaming process in step 103 is completed, the solid portion S of the three-dimensional network of the lattice structure L of the foamed additive manufacturing resin elastomer is embedded with closed-cell pores, and these closed-cell pores also have substantially intact shells of the thermally expandable microcapsules. During the foaming process, the thermal environment of the intermediate C should be carefully controlled to ensure that the expansion rate of the thermally expandable microcapsules matches the thermal curing rate of the base resin. In some embodiments, step 103 includes a heating process followed by a constant temperature process. During the heating process, the base resin in the solid portion S of the lattice structure L of the intermediate C gradually undergoes thermal curing due to the heat, while the thermally expandable microcapsules embedded in the solid portion S expand and foam due to the heat. The subsequent constant temperature process allows the thermal curing of the base resin to fully complete. Furthermore, in an embodiment in which step 103 includes a heating process and a constant temperature process, the thermally expandable microcapsules will begin to expand and foam during the heating process, that is, the temperature at the end of the heating process (which is also the beginning of the constant temperature process) is higher than the foaming starting temperature of the thermally expandable microcapsules. In another embodiment, step 103 includes multiple heating processes and constant temperature processes. For example, a first heating process and a first constant temperature process are performed first, followed by a second heating process and a second constant temperature process. In the first heating process, the base resin of the solid part S of the grid structure L of the intermediate C can be uniformly thermally cured throughout the entire intermediate C (for example, the surface and interior of the intermediate) due to the gentle heating; and the first constant temperature process that follows can allow the thermal curing effect of the base resin to fully react. However, the foaming starting temperature of the thermally expandable microcapsules was not reached in both the first heating process and the first constant temperature process.After completing the first temperature rising process and the first temperature maintaining process, the second temperature rising process is then carried out. At this time, the intermediate is further heated to a temperature at which the microcapsules can be foamed, and then the second temperature maintaining process is carried out. During the execution of the second temperature maintaining process, if there are any heat-expandable microcapsules embedded in the solid part S that have not completed expansion and foaming in the second temperature rising stage, they will complete foaming during the execution of the second temperature maintaining process.

[0056] Continue to explain step 103. Figure 5B As shown in FIG, in a thermal environment, the heat-expandable microcapsules are converted into gas due to the low-carbon alkane liquid contained therein. The volume increase caused by this liquid-gas conversion provides an outward expansion force F for the shell of the heat-expandable microcapsules. out At the same time, the base resin is also cured by heat in a hot environment, thus providing a resistance F to the outward expansion of the shell of the thermal expansion microcapsule. in When step 103 includes a heating process followed by a constant temperature process, since the rate of thermal curing of the base resin is roughly the same as the rate of expansion and bubbling of the thermally expandable microcapsules, the impact force F is greater during the heating process. out Keep approximately equal to the resistance F in In the subsequent constant temperature process, since the thermal expansion microcapsules have basically completed foaming, the microcapsules will no longer continue to grow, and the base resin will not expand or shrink during the thermal curing process. Therefore, no impact force F will occur in the constant temperature process. out With resistance F inWhen step 103 includes multiple heating and holding temperature processes, for example, in an embodiment in which a first heating process, a first holding temperature process, a second heating process, and a second holding temperature process are performed sequentially, since neither the first heating process nor the first holding temperature process reaches the foaming starting temperature of the thermally expandable microcapsules, only the thermal curing reaction of the base resin occurs during the first heating and holding temperature processes, while the thermally expandable microcapsules begin to foam during the second heating and holding temperature processes. The embodiment in which step 103 includes multiple heating and holding temperature processes will be described in further detail. The first heating process is to heat the intermediate C evenly by gently heating it, avoiding uneven heating inside and outside the intermediate C resulting in different degrees of thermal curing. This is because when the thermal curing reaction begins, the intermediate C will produce new cross-linking bonds and gradually transform the intermediate C from the embryo stage (green stage) to the mature stage. Due to the different heat conduction performance of these two stages, if the heating rate of the first heating process is not properly controlled, the thermal curing reaction of the intermediate C will not be ideal; when the first heating process ends, it is then continued to be heated for a period of time at the temperature finally reached by the first heating process to carry out the first constant temperature process. During the first constant temperature process, the intermediate C continues to be thermally cured until the entire body is evenly close to the mature stage. Since the base resin of the solid part S of the grid structure L of the intermediate C will not actually expand or shrink during the thermal curing process, and the operating environment of the first heating process and the first constant temperature process has not yet reached the temperature at which the thermal expansion microcapsules begin to foam, the impact force F has not yet occurred in the first heating process and the first constant temperature process. out With resistance F in The relative force. After the first heating process and the first constant temperature process are completed, the second heating process is carried out. In this stage, the thermal environment is slowly heated to a temperature at which the thermal expansion microcapsules embedded in the base resin can start to foam. Since the intermediate C has been close to the mature stage of polymer polymerization after the first heating process and the first constant temperature process, that is, the intermediate C before the start of the second heating process actually has a considerable number of thermally cured bonds, that is, before the start of the second heating process, the solid part S of the grid structure L of the intermediate C embedded with the thermal expansion microcapsules has stronger mechanical properties than when it was just produced from the 3D printer, that is, when the second heating process starts, the base resin can provide more sufficient resistance to the thermal expansion microcapsules. Due to the impact force F of the thermal expansion microcapsules expanding outward out The resistance F provided by the base resin to the outward expansion of the shell of the thermally expandable microcapsule in It is the relative action force - reaction force, so in the implementation method including multiple temperature rising process and constant temperature process, the impact force F is also maintained. out With resistance F inRoughly equal, that is, when the thermal expansion microcapsules expand and foam, their outward expansion force F out The resistance F does not exceed the mechanical strength of the base resin. in Therefore, the intermediate C will not cause lattice damage due to the foaming process. Finally, a second constant temperature process is then performed to ensure that the thermally expandable microcapsules that have not yet been fully foamed are fully foamed and to ensure that the intermediate C can complete thermal curing.

[0057] Through the process arrangement described above, the intermediate C produced by the 3D printer can expand uniformly, increase in volume and maintain the same lattice as before foaming. Figure 6 As shown (right: non-foamed additive manufacturing resin elastomer; left: foamed additive manufacturing resin elastomer obtained through step 103). In contrast, when the foaming process is not properly controlled, the curing rate of the base resin may be too much ahead of the expansion rate of the thermally expandable microcapsules, resulting in the impact force F of the thermally expandable microcapsules expanding outward. out The resistance of the base resin to the expansion of the thermally expandable microcapsules is insufficient to overcome the resistance of the base resin to the expansion of the thermally expandable microcapsules, so that the thermally expandable microcapsules cannot expand smoothly, which will result in the volume of the intermediate C cannot be efficiently enlarged; or, the curing rate of the base resin may lag too far behind the expansion rate of the thermally expandable microcapsules, resulting in the thermally expandable microcapsules being unable to expand smoothly under the impact force F of the thermally expandable microcapsules. out Greater than the resistance F of the base resin curing to the expansion of the thermal expansion microcapsules in , then the resistance F of the thermal expansion microcapsules to the expansion of the thermal expansion microcapsules obtained by the solidification of the base resin during the expansion process is in The antagonistic force is insufficient, so that the shell of the thermal expansion microcapsule cannot withstand the impact of the thermal expansion microcapsule expanding outward. out The volatile liquid contained in the thermal expansion microcapsules cannot form complete closed-cell pores during the conversion to gas, so that the lattice structure of the final additive manufacturing resin elastomer is broken. Figure 7 As shown on the left of the figure. The additive manufacturing resin elastomer formed after completing step 103 has a high volume foaming rate (for example, the volume of the additive manufacturing resin elastomer is about 100% to about 350% compared to the volume of the intermediate C), and the pores embedded in the solid part S in the three-dimensional network of the additive manufacturing resin elastomer are closed pores. The thermal expansion microcapsules constituting the pores still have a substantially complete shell after foaming. The spatial arrangement of the basic geometric shape formed by the solid part S constitutes a grid structure L. The grid structure L is complete and substantially maintains the same shape as before step 103, and is not deformed by heating, as shown in FIG. Figure 7 As shown in the figure on the right.

[0058] The present disclosure also provides an additive manufacturing resin elastomer formed by the above method. The features of the foamed dual-curing resin composition 205 that forms the additive manufacturing resin elastomer can be referred to above. The additive manufacturing resin elastomer includes a solid part S composed of large and small molecules contained in the base resin that are cross-linked and bonded to each other, and pores formed by the expansion of thermal expansion microcapsules embedded in the solid part; the grid structure L formed by the spatial arrangement of the basic geometric shape formed by the solid part S, and a plurality of grid structures L connected to each other are assembled into a three-dimensional network; the shape of the pores is a closed-cell pore formed by the thermal expansion microcapsule shell remaining roughly intact, so the shape of the pores is roughly circular, such as circular, elliptical or oval. The three-dimensional network is formed by additive manufacturing, and its specific steps can refer to the description of step 102 above. The overall density of the additive manufacturing resin elastomer is 100 kg / m 3 Up to 1000kg / m 3 , for example 100kg / m 3 , 500kg / m 3 、600kg / m 3 , 700kg / m 3 , 800kg / m 3 , 900kg / m 3 or 1000kg / m 3 In some embodiments, the additively manufactured resin elastomer includes a plurality of portions continuously distributed from one side to an opposite side (in some embodiments, the direction extending from the side to the opposite side is substantially parallel to the pulling direction D described above), and the difference between the density of each of the portions of the additively manufactured resin elastomer and the average density of the additively manufactured resin elastomer is less than 80 kg / m 3 and greater than or equal to 0kg / m 3 That is, the density of the three-dimensional network in the additively manufactured resin elastomer has sufficient uniformity. In some embodiments, the absolute value of the density gradient in the additively manufactured resin elastomer is less than 50 kg / (m 3 *cm) and greater than or equal to 0kg / (m 3 *cm), where the density gradient refers to the density variation per centimeter in the distance from one side of the additive manufacturing resin elastomer to the opposite side. That is, the density variation of the base resin in the additive manufacturing resin elastomer is sufficiently subtle without excessive variation. In some embodiments, the standard deviation of the density in the additive manufacturing resin elastomer is less than 32 kg / m 3 and greater than or equal to 0kg / m 3 , to have sufficient density uniformity to have good mechanical properties.

[0059] Continuing with the additive manufacturing resin elastomer, after the additive manufacturing resin elastomer undergoes a dual curing process of photopolymerization in step 102 and thermal curing in step 103, the components of the original foamable dual-curing resin composition are fully cross-linked, resulting in the final additive manufacturing resin elastomer having excellent mechanical properties, such as compressive strength, torsional stiffness, shear strength, impact resistance, tensile strength, elongation at break, and (trouser-shaped) tear strength. For example, the additively manufactured resin elastomer has a tensile strength of 3 MPa to 17 MPa, such as 3 MPa, 5 MPa, 7 MPa, 9 MPa, 11 MPa, 13 MPa, 15 MPa or 17 MPa; an elongation at break of 120% to 340%, such as 120%, 140%, 180%, 220%, 260%, 300% or 340%; and a (trouser-shaped) tear strength of 2 N / mm to 9 N / mm, such as 2 N / mm, 3 N / mm, 4 N / mm, 5 N / mm, 6 N / mm, 7 N / mm, 8 N / mm or 9 N / mm.

[0060] Continuing to explain the additive manufacturing resin elastomer. In some embodiments, the additive manufacturing resin elastomer can be as follows Figure 8 The intermediate body C is shown as having the shape of a shoe midsole. In these embodiments, when forming the intermediate body C, the printing direction (relative to the pulling direction D) is substantially parallel to the direction from the toe to the heel. In these embodiments, the three-dimensional network in the additively manufactured resin elastomer has a first density at the toe portion, a second density at the heel portion, and a third density between the toe portion and the heel portion, wherein the first density is greater than the second density, and both the first density and the second density are greater than the third density.

[0061] The following details how Figure 8 The density distribution and changes of the sole are shown. However, it should be understood that the following specific embodiments are intended to enable those skilled in the art to better understand the present disclosure, and are not intended to limit the scope of the present disclosure.

[0062] like Figure 8 The average density of the sole shown is about 817.14 kg / m 3 . Refer to Table 1 and Table 2, Figure 8 The shoe sole is divided into 15 equal sections from the heel to the toe, and these are sequentially designated as Position 1 to Position 15. The density at Positions 1 to 15 and the difference between each position and the average density are measured, as shown in Table 1. The density variation between each of Positions 1 to 15 and adjacent positions (e.g., Position 1 to Position 2, Position 2 to Position 3, and so on) is shown by the density gradient in Table 2. Figure 9 It is like Figure 8The waterfall chart shows the density of the shoe sole increasing and decreasing with position, where the x-axis indicates the position and the difference between the corresponding density and the average density, and the y-axis is in kg / m 3 . Figure 8 The three-dimensional network in the sole is shown to have sufficient uniformity as above.

[0063] Table 1:

[0064] Location <![CDATA[Density (kg / m 3 )]]> <![CDATA[Difference from the average density (kg / m 3 )]]> 1 738 -79.14 2 786 -31.14 3 799 -18.14 4 826 8.86 5 815 -2.14 6 819 1.86 7 820 2.86 8 796 -21.14 9 805 -12.14 10 834 16.86 11 867 49.86 12 869 51.86 13 835 17.86 14 831 13.86 15 821 3.86

[0065] Table 2:

[0066]

[0067]

[0068] Next, through Examples 1-1 to 1-5 in Table 3, Examples 2-1 to 2-5 in Table 4, and Examples 3-1 to 3-5 in Table 5, it is illustrated that the additively manufactured resin elastomer formed by the method disclosed herein has good bulk foaming rate, tensile strength, elongation at break, and (trouser-shaped) tear strength. Regarding the formula of the foamable dual-cure resin composition used in the embodiments, Tables 3, 4, and 5 all use the foamable dual-cure resin composition produced by TPK Electronic Materials, but different models of products are selected for the performance required by different products. Examples 1-1 to 1-5 in Table 3 all use the same foamable dual-cure resin composition, but when performing the foaming procedure, the temperature rise from room temperature to the expected arrival temperature, the time required for the temperature rise, and the temperature rise rate may be different, and the constant temperature and constant temperature time in the constant temperature process may also be different. Please refer to Table 3 for details. Examples 2-1 through 2-5 in Table 4 all use the same foamable dual-cure resin composition, but during the foaming process, the temperature rise from room temperature to the expected target temperature, the time required for temperature rise, and the temperature rise rate may vary. Furthermore, the settling temperature and settling time during the temperature settling process may also vary. For details, see Table 4. Examples 3-1 through 3-5 in Table 5 all use the same foamable dual-cure resin composition, but during the foaming process, the temperature rise from room temperature to the expected target temperature, the time required for temperature rise, and the temperature rise rate may vary. Furthermore, the settling temperature and settling time during the temperature settling process may also vary. For details, see Table 5.

[0069] Table 3:

[0070]

[0071]

[0072] Table 4:

[0073]

[0074]

[0075] Table 5:

[0076]

[0077]

[0078] Next, the comparative example in Table 6 illustrates that when the method disclosed herein is not used to form an additively manufactured resin elastomer, the molded product after foaming may produce uneven foaming, making the foamed molded product different from the shape before foaming, or causing the foamed molded product to burst due to excessive foaming. In Comparative Examples 1 to 6 in Table 6, the solidified body formed by the additive manufacturing process is a 30cm*30cm*30cm cube, and the solidified body undergoes heating conditions 1, heating conditions 2, and heating conditions 3 in Table 6 for foaming. Since the comparative examples did not undergo the foaming procedure of the present disclosure for foaming (for example, there is no slow heating process, etc.), the foamed molded products of Comparative Examples 1 to 2 are deformed and do not retain the cubic shape before foaming. The structures of the foamed molded products of Comparative Examples 3 to 6 even burst (such as Figure 7 (as shown on the left of the figure).

[0079] Table 6:

[0080]

[0081]

[0082] The additively manufactured resin elastomer formed by the method disclosed herein has a high volumetric expansion ratio, and the foaming process does not cause deformation of the three-dimensional network originally defined by additive manufacturing. In other words, the network structure in the final additively manufactured resin elastomer is intact and can maintain substantially the same shape as before foaming. After foaming, the final additively manufactured resin elastomer has a sufficiently uniform density, and the solid portions constituting the three-dimensional network of the additively manufactured resin elastomer are fully cured to achieve the desired mechanical properties of the three-dimensional network, such as good compressive strength, torsional stiffness, shear strength, impact resistance, tensile strength, elongation at break, and (trouser) tear strength.

[0083] This disclosure describes certain embodiments in considerable detail, but other embodiments are also possible. Therefore, the description of the embodiments contained in this disclosure should not be construed as limiting the scope and spirit of the appended claims. Modifications and variations of this disclosure may be made by one of ordinary skill in the art without departing from the scope and spirit of this disclosure. This disclosure covers such modifications and variations as long as they fall within the scope and spirit of the appended claims.

Claims

1. A method for additive manufacturing of foamable dual-cure resin, characterized in that: include: Performing a resin providing process, including providing a foamable dual-cure resin composition, the foamable dual-cure resin composition including a base resin and a thermally expandable microcapsule; An additive manufacturing process is performed, comprising placing the foamable dual-cure resin composition in a continuous liquid interface production printer, causing the base resin to undergo a photopolymerization reaction under ultraviolet light to form a solid portion, thereby defining a plurality of grid structures, wherein: The plurality of grid structures are assembled to form a three-dimensional network, and the three-dimensional network forms an intermediate body; and The thermally expandable microcapsules in the foamable dual-cure resin composition are embedded in the solid portions of the plurality of lattice structures of the intermediate body as the base resin in the foamable dual-cure resin composition undergoes a photopolymerization reaction; and A foaming process is performed, including removing the intermediate from the printer station of the continuous liquid interface production and placing it in a hot environment, so that the thermally expandable microcapsules in the solid part embedded in the multiple grid structures are expanded by heat, thereby enlarging the three-dimensional network of the intermediate due to the expansion of the thermally expandable microcapsules, and causing the overall volume of the intermediate to expand to complete a final foaming, wherein the intermediate is heated in the hot environment to complete a thermal curing, and finally forms an additive manufacturing resin elastomer.

2. The method for additive manufacturing of foamed dual-cure resin according to claim 1, characterized in that: The resin providing process provides the foamable dual-curing resin composition having a slight sedimentation phenomenon based on a Toxoplast law.

3. The method for additive manufacturing of foamed dual-cure resin according to claim 2, characterized in that: The difference in density between the base resin and the thermally expandable microcapsules in the foamable dual-curing resin composition is less than 1 g / mL and greater than or equal to 0 g / mL.

4. The method for additive manufacturing of foamed dual-cure resin according to claim 1, wherein: When the additive manufacturing process is performed, the thermally expandable microcapsules do not react to the irradiation of the ultraviolet light.

5. The method for additive manufacturing of foamed dual-cure resin according to claim 1, wherein: The foaming process includes a heating process and a constant temperature process. The heating process includes heating from room temperature to 90°C to 220°C at a rate of 1°C to 3.5°C per minute. The constant temperature process includes continuing heating at a final temperature reached by the heating process after the heating process is completed and performing it for 1 hour to 5 hours.

6. The method for additive manufacturing of foamed dual-cure resin according to claim 1, wherein: The foaming process includes a first temperature rising process, a first constant temperature process, a second temperature rising process and a second constant temperature process in sequence, wherein the first temperature rising process is heating from room temperature to a first temperature of 100°C to 120°C in 0.75 hours to 1.25 hours, the first constant temperature process is continuously heated at the first temperature for 3.5 hours to 4.5 hours, the second temperature rising process is heating from the first temperature to a second temperature of 130°C to 150°C in 20 minutes to 40 minutes, the second constant temperature process is performed when the second temperature is reached, and the second constant temperature process is continuously heated at the second temperature for 5 minutes to 15 minutes.

7. The method for additive manufacturing of foamed dual-cure resin according to claim 1, wherein: The foaming process is performed under standard atmospheric pressure.

8. An additive manufacturing resin elastomer manufactured by the method for additive manufacturing of a foamed dual-cure resin according to claim 1, characterized in that: Include: The three-dimensional network formed by additive manufacturing is composed of the plurality of interconnected lattice structures, each of the plurality of lattice structures includes a spatial arrangement of a basic geometric shape formed by the solid portion, and the three-dimensional network formed by the plurality of lattice structures constitutes the solid portion of the additively manufactured resin elastomer; and The solid part has a plurality of foamed pores inside, and the absolute value of a density gradient in a first direction, an absolute value of a density gradient in a second direction, and an absolute value of a density gradient in a third direction of the additively manufactured resin elastomer are less than 50 kg / (m 3 *cm), and the first direction, the second direction and the third direction are perpendicular to each other.

9. The additively manufactured resin elastomer according to claim 8, wherein: Each of the plurality of foamed pores is a closed-cell pore.

10. The additively manufactured resin elastomer according to claim 8, wherein: The plurality of foamed pores cause the volume of the additively manufactured resin elastomer to expand by 100% to 350% compared to that before foaming.

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