A method and product for solid support bath-assisted 3D printing

Abstract

This invention relates to a method and product for solid support bath-assisted 3D printing, comprising the following steps: preparing silicone elastomer ink; loading the silicone elastomer ink into a printing syringe; printing in a container containing a solid matrix with a certain particle size or angle of repose according to set printing requirements; after printing, heating the entire container for a certain period of time; removing the semi-cured printed part and continuing heating to obtain a fully cured printed component. The method of this invention expands the range of printing ink selection, allowing printing in solid particles or matrices of different particle sizes or angles of repose. By adjusting printing parameters, complex three-dimensional structures can be printed using simple printing equipment with only the support of a solid particle matrix, and the printed component can be obtained after simple post-processing.

Description

Technical Field

[0001] This invention belongs to the field of additive manufacturing technology, specifically relating to a method and product for 3D printing assisted by a solid support bath. Background Technology

[0002] Currently, with the rapid development of flexible wearable devices, soft robots, and healthcare devices, the preparation and research of soft materials have attracted widespread attention from researchers. Silicone elastomers, in particular, have been extensively studied due to their good thermal stability, chemical resistance, and mechanical compliance. However, the traditional molding process for silicone elastomers—template casting—often suffers from low efficiency and limitations such as simple structures and single functions. 3D printing technology, a customizable technology capable of complex structural designs, is beneficial for the molding of soft materials. In 3D printing, direct ink writing (DIW) is a material extrusion-based printing technology with the most diverse range of printing materials, such as liquid crystal elastomers, hydrogels, and elastic polymers. For direct ink writing, the ink material only needs to meet printability requirements. Therefore, in DIW technology, ink materials can be customized according to the required functions. To achieve DIW printing of silicone elastomers, researchers add rheology modifiers or fillers to impart shear-thinning and shear-yielding properties. However, this inevitably alters the inherent properties of the silicone elastomer material, and excessive filler can cause nozzle clogging and uneven mixing. Therefore, researchers proposed an embedding method for 3D printing, using a support bath to address the issues arising from high filler content in the ink. However, this method faces challenges in fabricating complex components with multiple materials and functions. Other reports have suggested installing Joule heaters at the printing nozzle to rapidly complete the printing and curing of silicone elastomer materials, but this requires equipment modification. Based on these issues, this invention proposes printing silicone elastomers within a solid matrix, with the solid matrix acting as a support, enabling the printing of complex structures. Summary of the Invention

[0003] In order to overcome the problems existing in the prior art, the present invention provides a method and product for solid support bath-assisted 3D printing.

[0004] A method for solid support bath-assisted 3D printing includes the following steps:

[0005] S1. Formulate silicone elastomer ink;

[0006] S2. Load the silicone elastomer ink into a printing syringe and print in a container containing a solid matrix with a certain particle size or angle of repose according to the set printing requirements;

[0007] S3. After printing, heat the container containing the solid matrix for a certain period of time;

[0008] S4. Remove the partially cured printed part from the heat and heat it again to obtain a fully cured printed component.

[0009] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the silicone elastomer ink comprises PDMS silicone rubber, silicone diluent and retarder, or comprises PDMS silicone rubber and retarder.

[0010] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the formulation steps of the silicone elastomer ink include:

[0011] S111. PDMS silicone rubber is mixed with 1 wt% retarder and then cooled to obtain the first mixture;

[0012] S112. Add a curing agent to the first mixture, then mix and cool to obtain a second mixture;

[0013] S113. Add a diluent to the second mixture, mix, and cool to obtain a silicone elastomer ink.

[0014] In addition to the aspects described above and any possible implementations, an implementation is further provided in which the particle size is less than or equal to 1000 micrometers.

[0015] In addition to the aspects and any possible implementations described above, an implementation is further provided, wherein S2 includes: S2.1. fixing a syringe containing silicone elastomer ink above a printing platform, while fixing a container containing a solid particle matrix on the printing platform;

[0016] S2.2. Adjust the position of the syringe needle relative to the container, adjust the printing speed, printing pressure, and printing depth, and complete the printing of silicone elastomer ink in the container according to the set printing requirements.

[0017] In addition to the aspects described above and any possible implementation, a further implementation is provided in which the printing depth of the silicone elastomer ink with yield stress is 10-30 mm, the printing pressure is 50-80 psi, and the printing speed is 1-3 mm / s; and the printing pressure of the silicone elastomer ink without yield behavior is 20 psi, the printing speed is 1-5 mm / s, and the printing depth is 10 mm.

[0018] In addition to the aspects described above and any possible implementations, an implementation is further provided in which the angle of repose is less than 50°.

[0019] In addition to the aspects and any possible implementations described above, a further implementation is provided in which the solid matrix having particle size is polytetrafluoroethylene solid, magnetic powder or carbon nanotubes, and the solid matrix having an angle of repose is baking soda, sugar, salt, sand or glass microspheres.

[0020] In addition to the aspects described above and any possible implementation, an implementation is further provided in which the linewidth of the printed component ranges from 342.5 to 679.4 μm.

[0021] The present invention also provides a printed component, which is prepared by the method described above.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention discloses a method for solid-support bath-assisted 3D printing, comprising: preparing a silicone elastomer ink; loading the silicone elastomer ink into a printing syringe; printing in a container containing a solid matrix with a certain particle size or angle of repose according to set printing requirements; after printing, heating the container containing the solid matrix for a certain period of time; removing the semi-cured printed part and further heating it to obtain a fully cured printed component. This invention expands the range of printing ink options and uses simple printing equipment. Complex three-dimensional structures can be printed with only the support of a solid particle matrix, and the component can be obtained after simple post-processing. In this invention, the solid matrix supports the ink material to achieve the printing of structures that are wider at the top and narrower at the bottom, as well as three-dimensional structures composed of lines. The post-processing of the printed structure is simple. Furthermore, the solid matrix can be recycled. This invention can also achieve printing with inks that do not produce yield stress, reducing the rheological requirements of the printing ink material. Simultaneously, it enables printing in functional solid matrices, endowing silicone elastomers with different functionalities and providing possibilities for printing with more functional solid matrices. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the printing system in this invention.

[0025] Figure 2 This is a schematic diagram of the solid matrix-assisted ink direct writing process in this invention.

[0026] Figure 3 These are rheological property diagrams for two silicone elastomer ink materials.

[0027] Figure 4 This is a graph showing the variation in the contact angle between different solid substrates and Ecoflex0030 ink.

[0028] Figure 5 This is a schematic diagram of the angle of repose of different solid matrix powders.

[0029] Figure 6 This is an actual picture of lines printed with Ecoflex 0030 printing ink at 20 psi pressure.

[0030] Figure 7 These are surface and cross-sectional topographic images of lines printed in glass microspheres using two inks: SE1700+6% Thinner and Ecoflex0030.

[0031] Figure 8 These are scanning electron microscope (SEM) images of the cross-sections of silicon elastomer printing filaments prepared by printing with two inks, SE1700+6% Thinner and Ecoflex0030, in a baking soda support bath.

[0032] Figure 9 These are the filament dimensions and microscope images of the SE1700+6% Thinner printing ink at different printing pressures at a printing speed of 1 mm / s, as described in this invention.

[0033] Figure 10 This shows the relationship between the filament size and theoretical diameter of SE1700+6% Thinner printing ink under different pressures, the relationship between the y / x value and the printing pressure, and electron microscope images of the filament cross-section.

[0034] Figure 11 This is the filament size of SE1700+6% Thinner printing ink at different printing speeds under a printing pressure of 80psi.

[0035] Figure 12 This invention relates the relationship between the y / x value of the printing filament and the printing speed of the SE1700+6% Thinner printing ink at different printing speeds, as well as electron microscope images of the cross-section of the printing filament.

[0036] Figure 13 These are the filament sizes for SE1700+6% Thinner printing ink at different printing depths.

[0037] Figure 14 This is a schematic diagram of the printing path of Ecoflex 0030 ink, including (a) a schematic diagram of a trapezoidal path; (b) an actual printed image; (c) a normal closed path and a photograph of the pattern printed in baking soda; and (d) an improved path and a photograph of the pattern printed in baking soda.

[0038] Figure 15 It is a 3D structure printed with SE1700+6% Thinner printing ink in baking soda solid.

[0039] Figure 16 It is a conductive fiber printed in carbon nanotubes using SE1700+6% Thinner printing ink.

[0040] Figure 17 It is a thin film printed with SE1700+6% Thinner printing ink in baking soda solid for triboelectric power generation. Detailed Implementation

[0041] To better understand the technical solution of this invention, the content of this invention includes, but is not limited to, the specific embodiments described below. Similar technologies and methods should be considered within the scope of protection of this invention. To make the technical problems to be solved, the technical solutions, and advantages of this invention clearer, a detailed description will be provided below in conjunction with the accompanying drawings and specific embodiments.

[0042] It should be understood that the embodiments described in this invention are merely some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without inventive effort are within the scope of protection of this invention.

[0043] The terminology used in the embodiments of this invention is for the purpose of describing particular embodiments only and is not intended to limit the invention. The singular forms “a,” “the,” and “the” as used in the embodiments of this invention and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0044] This invention provides a method for solid support bath-assisted 3D printing, comprising the following steps:

[0045] S1. Formulate silicone elastomer ink;

[0046] S2. Load the silicone elastomer ink into a printing syringe and print in a container containing a solid matrix with a certain particle size or angle of repose according to the set printing requirements;

[0047] S3. After printing, heat the container containing the solid matrix for a certain period of time;

[0048] S4. Remove the partially cured printed part from the heat and heat it again to obtain a fully cured printed component.

[0049] The silicone elastomer ink includes PDMS silicone rubber, silicone diluent, and a retarder, or includes PDMS silicone rubber and a retarder.

[0050] Preferably, the silicone elastomer ink is a silicone elastomer ink with yield stress, including Dow Corning SE1700 PDMS silicone rubber, Silicone Thinner from Smooth-On, a retarder, and pigments; or it is a silicone elastomer ink without yield behavior, which includes: Ecoflex 0030 PDMS silicone rubber from Smooth-On and a retarder.

[0051] Preferably, the formulation steps of the silicone elastomer ink with yielding behavior include:

[0052] S111. After mixing SE1700 main agent with 1 wt% retarder and cooling, a first mixture is obtained;

[0053] S112. Add SE1700 curing agent to the first mixture, then mix and cool to obtain the second mixture;

[0054] S113. Add 6 wt% diluent and 0.2 wt% pigment to the second mixture, mix, and cool to obtain silicone elastomer ink.

[0055] Preferably, the preparation steps of the silicone elastomer ink without yielding behavior include:

[0056] S121. Mix component B of Ecoflex 0030 PDMS silicone rubber from Smooth-On Corporation of the United States with 1 wt% retarder, and then cool to obtain the first cooled product;

[0057] S122. Add component A of Ecoflex0030 to the first cooled material, mix again, and cool to obtain a silicone elastomer ink that does not have yielding behavior.

[0058] Preferably, S2 includes: S2.1. Fixing a syringe containing silicone elastomer ink above the printing platform, and simultaneously fixing a container containing a solid matrix on the printing platform;

[0059] S2.2. Adjust the position of the syringe needle relative to the container, adjust the printing speed, printing pressure, and printing depth, and complete the printing of silicone elastomer ink in the container according to the set printing requirements.

[0060] Preferably, the printing depth of the silicone elastomer ink with yield stress is 10–30 mm, the printing pressure is 50–80 psi, and the printing speed is 1–3 mm / s; the printing pressure of the silicone elastomer ink without yield behavior is 20 psi, the printing speed is 1–5 mm / s, and the printing depth is 10 mm.

[0061] Preferably, the solid particle matrix is ​​baking soda, sugar, salt, sand or glass microspheres, solid polytetrafluoroethylene, magnetic powder or carbon nanotubes.

[0062] As an embodiment of the present invention, the present invention also provides a printing component, which is prepared by the method described in the present invention, wherein the width of the printing filaments of the printing component ranges from 342.5 to 679.4 μm.

[0063] Specifically, the process of this invention is as follows:

[0064] The implementation of this invention begins with ink preparation. Two silicone elastomers were selected as ink materials: BASF SE1700 PDMS silicone rubber and Smooth-On Ecoflex 0030 PDMS silicone rubber. SE1700 with 6% silica gel diluent represents a fluid exhibiting shear-thinning properties and yield stress, while Ecoflex 0030 is a Newtonian fluid, representing a fluid without shear-thinning and yield stress. Shear-thinning is characterized by a decrease in ink viscosity with increasing shear rate, allowing the ink to be smoothly extruded from the nozzle. The presence of yield stress reflects the process of ink being extruded from the nozzle and deposited on the substrate. When the shear force is less than the yield stress, the storage modulus of the ink material is greater than its loss modulus, exhibiting solid-like behavior. When the shear stress is greater than the yield stress, the loss modulus is greater than the storage modulus, exhibiting liquid-like behavior. SE1700 is a silicone elastomer with 20% fumed silica added. The addition of 6% silica gel diluent aims to reduce the yield stress, making the rheological requirements of the printing ink lower and more universal. For Ecoflex0030 silicone elastomer, its loss modulus is always greater than its storage modulus, exhibiting liquid behavior, and therefore it cannot be printed in air.

[0065] Then, this invention verified the printability of Ecoflex0030 printing ink in a baking soda matrix and the effects of printing pressure, printing speed and printing depth on the size and morphology of the printed components when printing SE1700+6% Thinner printing ink in a baking soda solid matrix.

[0066] Furthermore, this invention solves the problem of shape closure in solid matrix printing by improving the printing path, and finally obtains a structure that is wide at the top and narrow at the bottom, a three-dimensional structure composed of lines, and an upright cilia array structure through path design.

[0067] Finally, this invention demonstrates printing in sodium bicarbonate solids, polytetrafluoroethylene solids, magnetic powders, and carbon nanotubes, providing ideas for printing on more solid matrices.

[0068] This invention is achieved using the following technical solution:

[0069] 1) Preparation of organosilicon ink materials

[0070] The preparation process for SE1700 ink is as follows:

[0071] First, mix 5g of SE1700 main agent and 1wt% of retarder in a planetary mixer at 3000rpm for 3 minutes, and then place it in a -35℃ refrigerator to cool for 5 minutes.

[0072] Add 0.5g of SE1700 curing agent to the cooled material, mix at 3000rpm for 3 minutes, and then cool for 5 minutes.

[0073] Finally, add 6 wt% Thinner to the cooled material and mix again at 3000 rpm for 3 minutes, then cool again for 5 minutes to obtain SE1700 ink.

[0074] The preparation process of Ecoflex0030 ink is as follows:

[0075] First, mix 3g of Ecoflex0030 (Part B) with 1wt% of polymerization inhibitor in a planetary mixer at 3000rpm for 3 minutes, then place it in a -35℃ refrigerator to cool for 5 minutes.

[0076] Add 3g Ecoflex0030 (Part A) and 0.2wt% pigment to the cooled material and mix for 3 minutes. Then cool for 5 minutes to obtain Ecoflex0030 ink.

[0077] 2) Selected solid matrix

[0078] The solid matrix used in this invention has a certain particle size or a certain angle of repose, such as... Figure 5 As shown, the angle of repose of the solid matrix powder is used to characterize the powder's flowability. The angle of repose refers to the tangent of the angle between the solid particle and the horizontal plane when the particle reaches equilibrium on an inclined plane. The larger the angle of repose, the more difficult it is for the particles to flow. Specifically, this invention selects solid matrices with an angle of repose less than 50°. Solid matrices with angles smaller than this indicate good solid flowability and are suitable for printing. This invention selects baking soda, sugar, salt, and sand or glass microspheres of a certain mesh size as solid matrices. The angle of repose of baking soda is 41.4°, sugar is 39.3°, salt is 39.1°, hollow glass microspheres are 34.4°, 300-mesh sand is 42.8°, and 200-mesh sand is 34.7°.

[0079] The solid particle size must be less than or equal to 1000 micrometers. If the particle size is too large, steric hindrance will exist between the solid matrix particles, resulting in excessively large porosity between particles, thereby reducing the support for the ink. The inherent density of the solid matrix must be greater than 0.5 g / cm³. 3 And simultaneously less than 10g / cm 3 When printing solids in a container, i.e. when the needle tip is inserted into the solid particles and ink is squeezed out, if the density of the solid matrix is ​​too small, the solid matrix is ​​too light and easily carried away by the printing needle; if the density of the solid matrix is ​​too large, it will squeeze the ink and cause it to deform and break. Based on the above requirements, this invention selects polytetrafluoroethylene solid, magnetic powder or carbon nanotubes for printing.

[0080] Furthermore, when the aforementioned baking soda, sugar, salt, sand, or glass microspheres, solid PTFE, magnetic powder, or carbon nanotubes come into contact with Ecoflex 0030 ink, the contact angle formed is less than 60°. The contact angle indicates the compatibility between the solid and liquid components, and this angle also indicates that the aforementioned solid matrix meets the printing requirements. Figure 4 The figure shows the contact angles between different solid matrices and Ecoflex0030 ink, which are used to characterize the diffusion behavior between the ink material and the solid.

[0081] The contact angle of Ecoflex 0030 ink droplets on different solid surfaces (powder pressed into sheets) changes over time, and the ink exhibits spreading behavior. Solid substrates with a contact angle between 20 and 40° are preferred for printing. Ecoflex 0030 ink has a relatively high contact angle with hollow glass microspheres and sand, approximately 40°, followed by baking soda, salt, and PTFE, with contact angles of approximately 30°. Sugar has the lowest wettability, at approximately 20°.

[0082] 3) Build a printing system and perform printing.

[0083] like Figure 1 As shown, in the printing system of this invention, a container containing a solid matrix is ​​placed on the worktable of the dispensing machine. The worktable is equipped with X-axis, Y-axis and Z-axis according to one of its corners. The printing syringe is placed above the worktable, with a printing needle at its front end and a pressure controller at the other end to control the gas pressure supplied to the printing syringe by the air pump. The dispensing machine is connected to the pressure controller and a PC. Under the control of the PC, the printing method in the container is controlled. The printing speed and printing depth can be set according to the pre-design requirements.

[0084] During printing, the syringe containing the ink material prepared in step 1) is first fixed on the dispensing machine's worktable. Then, a container holding the solid matrix is ​​placed on the worktable. The starting point for printing is determined by controlling the X and Y axes of the printer's worktable, and the depth of the syringe from the solid surface is controlled by adjusting the Z axis. During printing, according to the set printing requirements, the printing pressure is adjusted by controlling the pressure controller, and the printing parameters of the dispensing machine, such as printing speed, are controlled via the PC. The movement of the dispensing machine and the design of the printing path are also controlled. When using SE1700+6% Thinner ink, this invention selects a printing needle with an exposed length of 25.4 mm and an inner diameter of 0.34 mm. This size of printing needle is ideal for continuous printing of components within a given printing pressure and speed range. Alternatively, a printing needle with an exposed length of 38 mm and an inner diameter of 0.42 mm can achieve printing at different depths, with a printing pressure of 50–80 psi, a printing speed of 1–3 mm / s, and a printing depth of 10–30 mm. This invention utilizes the linewidth of the printed components at these five different depths, such as… Figure 12 As shown, the linewidths are 515.8 μm, 503.1 μm, 503.0 μm, 497.0 μm, and 508.8 μm, respectively. The linewidth of the printed component did not change significantly, indicating that within this range, the printing depth has no significant impact on the linewidth of the printed component.

[0085] This invention uses Ecoflex0030 ink and a print head with an exposed length of 25.4 mm, an inner diameter of 0.34 mm, a printing pressure of 20 psi, and a printing speed of 1–3 mm / s. The resulting printed components are as follows: Figure 6 As shown.

[0086] The concentration of dilute hydrochloric acid used for post-processing of the printed components is 0.1 mol / L.

[0087] SE1700+6% Thinner ink, when the pressure is 50-80 psi and the printing speed is 1-3 mm / s, produces printed components with linewidths ranging from 342.5 to 679.4 μm and y / x values ​​ranging from 0.7122 to 0.8093. When the printing depth is 10-30 mm, the linewidth of the printed components remains basically unchanged. After improving the printing path in the printing requirements, the printed graphics are significantly more complete.

[0088] 4) Assisted 3D printing based on solid material support bath

[0089] This invention utilizes printing techniques in solids such as baking soda, carbon nanotubes, polytetrafluoroethylene (PTFE), and Fe3O4 magnetic powder. Printed components using baking soda retain pits left by the adhering baking soda particles after surface removal; these pits increase the surface roughness, potentially enhancing triboelectric output. Printed components using carbon nanotubes exhibit conductivity due to the adhering carbon nanotubes, suitable for sensing applications. Printed components using PTFE benefit from the hydrophobic nature of PTFE, improving surface hydrophobicity. The use of Fe3O4 magnetic powder imparts a magnetic intelligent response to the printed components. This invention also includes two silicone elastomer inks: SE1700 + 6% Thinner and Ecoflex0030. Figure 2 To assist the direct writing process of solid matrix inks, Figure 3 The rheological properties of the two silicone elastomer ink materials were examined. It was found that the SE1700+6% Thinner ink exhibits a yield stress point (intersection). Before the yield stress point, the storage modulus of the ink material is greater than the loss modulus, exhibiting solid-like behavior. After the yield stress point, the loss modulus is greater than the storage modulus, exhibiting liquid-like behavior. For the Ecoflex0030 ink material, the loss modulus is always greater than the storage modulus, and no yield stress exists. These two inks are not printable in air, but printing with the solid matrix provided by this invention is possible. Both inks can be printed in glass microspheres. A needle with an inner diameter of 0.52 mm was selected for printing large-diameter components. Transparent glass microspheres with a particle size range of 200-400 μm were used as a solid support bath. After curing, the printed components were placed under a camera to observe the surface morphology, and the cross-sectional morphology of the printed components was observed by cutting along the lines. Figure 7 These are corresponding optical photographs, with each small square representing 1 mm. Figures a1 and d1 show that the silicone rubber surface is entirely covered by glass spheres. The Ecoflex 0030 filaments exhibit significant unevenness in thickness. The filaments obtained using SE1700 + 6wt% Thinner show a boundary between the ink and the solid, with the solid adhering to the ink in an embedded manner. In Figures a2 and d2, the glass spheres are embedded within the Ecoflex 0030 ink, unlike the SE1700 + 6wt% Thinner ink filaments which have a clear boundary. Furthermore, by increasing the printing speed to reduce the print line size, observing the cross-sections of the print lines with different inks reveals that in Figure a3, the SE1700 + 6wt% Thinner ink still shows a boundary with the glass spheres, while Figure d3 contains more glass spheres. This demonstrates that in the printing technology provided by this invention, the rheological properties of the ink have a significant impact on the final filament.

[0090] In other words, the present invention uses the above-prepared silicone elastomer ink to construct complex structures through solid particle matrix-assisted 3D printing, and the method specifically includes the following steps:

[0091] S1) Formulate silicone elastomer ink;

[0092] S2) Construct a printing system, load the above-mentioned printing ink into a syringe, and print on a solid matrix;

[0093] S3) Place the container printed with semi-cured ink and solid matrix into an 80℃ oven for curing for 6 hours;

[0094] S4) After curing, the printed component formed by ink in the solid matrix is ​​taken out, post-processed, and heated again to obtain the printed component.

[0095] The specific steps of S2) are as follows:

[0096] S2.1) Fix the syringe containing ink material onto the dispensing machine's worktable, place the container containing the solid matrix on the worktable, and determine the printing start point by controlling the X and Y axes.

[0097] S2.2) Adjust the Z-axis to control the depth of the printing system from the solid surface, and adjust the printing pressure, printing speed, and printing depth to print the printing filament.

[0098] In S2.2), the printing depth when printing SE1700+6% Thinner ink is 10-30 mm, the printing pressure is 50-80 psi, and the printing speed is 1-3 mm / s; the printing pressure when printing Ecoflex0030 ink is 20 psi, the printing speed is 1-5 mm / s, and the printing depth is 10 mm.

[0099] The post-processing step in S4) is as follows:

[0100] For treating solid baking soda, the printed component is immersed in 0.1 mol / L dilute hydrochloric acid and stirred for 48 hours, then soaked in hot water for 48 hours, with the water changed. After soaking, the printed component is rinsed with distilled water 3-5 times to remove residual solution from the surface, and finally dried in an 80℃ oven for 12 hours. For other insoluble solid matrices, the solid on the surface of the printed component is first blown off with a blower, then sonicated in ethanol for 6 hours, followed by rinsing with distilled water 3-5 times, and finally dried.

[0101] The method enables printing using Ecoflex 0030 ink, such as... Figure 6As shown. This method, at a printing speed of 1 mm / s and a printing pressure ranging from 50 to 80 psi, produces SE1700+6% Thinner ink filaments as follows: Figure 8 As shown, the linewidth of the printed filament increases with increasing pressure, ranging from 342.5 to 679.4 μm. Figure 9 Filament size and microscope images at different printing pressures using SE1700+6% Thinner printing ink at a printing speed of 1 mm / s. Figure 10 The relationship between the filament size and theoretical diameter of SE1700+6% Thinner printing ink under different pressures, the relationship between the y / x value and the printing pressure, and electron microscope images of the filament cross-section. Figure 10 'a' represents the relationship between its characteristic dimension and theoretical diameter. When the pressure is 80 psi, the printed filament width deviates the most from the theoretical value. Figure 10 In diagram b, the width of the printing filament cross-section is x, and the height of the cross-section is y. The y / x ratio ranges from 0.71 to 0.81. It can be seen that the greater the printing pressure, the smaller the ratio, indicating that the cross-section deviates more significantly from a circular shape. Figure 10 c is an electron microscope image of the corresponding cross-section of the printing filament. The printing filament obtained by this invention exhibits a "bun-like" shape, with a raised top and a relatively flat bottom. This is because when the needle penetrates into the solid, it is equivalent to printing on a solid particle platform, hence the relatively flat bottom. Figure 11 This study examines the effect of printing speed on filament size at a printing pressure of 80 psi. Higher printing speeds result in smaller filament linewidths. When the printing speed increases from 1 mm / s to 3 mm / s, the filament linewidth decreases from 679.4 μm to 378.7 μm due to filament stretching. Figure 12 The images show electron microscope (EM) images of the corresponding y / x values ​​and cross-sections of the printing filament. They indicate that the higher the printing speed, the closer the y / x ratio is to 1, the finer the printing filament, and the closer the cross-section is to a circle. Figure 13 The linewidth of the filament for SE1700+6% Thinner printing ink at different printing depths shows that the resulting linewidth does not change significantly at different printing depths.

[0102] To improve the printing path of Ecoflex 0030 ink, place the ink (with a small amount of luminescent powder added) near the container wall of a container filled with baking soda, but not directly against it (there should still be solid between the nozzle and the container wall). Then, under a printing pressure of 20 psi, apply the ink along the container wall. Figure 14 In (a), trapezoidal patterns are printed at speeds of 1 mm / s, 2 mm / s, and 3 mm / s, respectively. Figure 14In (b), the starting and ending points cannot coincide, and the faster the printing speed, the more difficult it is for the pattern to close. This is mainly because when the printing needle is lifted upwards after printing, it carries away the ink from the end point, causing the pattern to fail to close. To eliminate the interference of the container wall on the printed pattern, printing was performed in baking soda solid at speeds of 1 mm / s and 2 mm / s along the normal path. Figure 14 In step (c), observation revealed that the ink volume was relatively low at the point where the beginning and end met. The final step was to extend the path to ensure that the ink could intersect with the ink at the starting point. Figure 14 (d) was printed in baking soda powder along the improved path at speeds of 1 mm / s and 2 mm / s. The amount of ink at the joints of the improved path was significantly increased. Figure 14 (d) in the figure illustrates that the improvement of its path is beneficial to the integrity of the printed pattern.

[0103] Following the above method, the printing path of SE1700 ink was improved, and a 3D structure was ultimately fabricated through path design. Figure 15 As shown, a triangular pyramid supported by lines was printed, which differs from the layer-by-layer stacking printing method. Simultaneously, an inverted pyramid structure, wider at the top and narrower at the bottom, was also printed, unlike conventional 3D printing methods which can only print structures that are narrower at the top and wider at the bottom. Furthermore, a cilia array structure can be printed vertically. The printing of these diverse structures benefits from the support of the solid matrix, requiring neither additional support components nor modifications to the printer. The printing method provided by this invention holds the promise of enabling the printing of more intricate and complex structures, and even those that are difficult to achieve using other methods.

[0104] Based on this method, the present invention embeds functional solids on the surface of the printing filament, endowing the printed structure with the properties of a solid matrix. For example... Figure 16 The image shows silicon elastomer fibers printed in carbon nanotubes. These fibers can be stretched and bent, and their electrical resistance changes as the fibers are stretched. Figure 17 This invention involves printing a two-layer thin film in baking soda. The increased surface roughness allows it to be used for triboelectric power generation. The invention also involves extruding printing ink between solid particles, embedding these particles into the surface of the printed component. This process allows inks that cannot be printed in air to be printed within a solid matrix, thanks to the encapsulation of solid particles.

[0105] Secondly, if functional solid particles are used for printing, functional printed composite materials can be directly formed after printing. For example, the silicone rubber / Fe3O4 composite formed by printing ink in iron powder is magnetic. SE1700 + 6% diluent is an ink with yield strength and can be printed in air using conventional printing methods. This method can impart surface structure and functionality through surface solid particles.

[0106] Ecoflex00-30 is an ink that does not have yield strength and cannot be printed in the air using conventional methods, but this method can be used to print it.

[0107] These two inks represent that this method can be used regardless of whether the ink has yield strength. After printing, the solids on the surface of the printed component can be washed off or retained. If retained, they can be used together with the printed component as a composite material.

[0108] The following specific examples will be used to illustrate this.

[0109] Example 1

[0110] Weigh 5g of SE1700 main agent, add 1wt% retarder, and mix in a planetary mixer at 3000rpm for 3 minutes. Cool in a refrigerator for 5 minutes. Add 0.5g of SE1700 curing agent and mix at 3000rpm for 3 minutes. Remove and freeze for 5 minutes. Add 6% diluent and 0.2% pigment and mix for 3 minutes. After mixing, freeze in a refrigerator for 5 minutes. Repeat the mixing and freezing process twice to ensure thorough mixing. After mixing, pour into a syringe and mix in a mixer at 3000rpm for 3 minutes to remove bubbles.

[0111] A stainless steel needle with an inner diameter of 340 μm and an exposed needle length of 25.4 mm was installed on the syringe. The printing pressure was set to 50 psi, the printing speed to 1 mm / s, and the printing depth to 10 mm. The printing was performed in baking soda solid.

[0112] Place the container containing baking soda in an 80℃ oven to cure for 6 hours.

[0113] Prepare a 0.1 mol / L dilute hydrochloric acid solution, put the printed part into it and stir for 48 hours, then soak it in hot water for 48 hours, changing the water as needed. After soaking, rinse the sample with distilled water 3-5 times to remove any residual solution on the surface, and finally place the sample in an 80℃ oven to dry for 12 hours.

[0114] In this implementation case, the obtained printing filament linewidth is 342.5 μm.

[0115] Example 2

[0116] Weigh 5g of SE1700 main agent, add 1wt% retarder, and mix in a planetary mixer at 3000rpm for 3 minutes. Cool in a refrigerator for 5 minutes. Add 0.5g of SE1700 curing agent and mix at 3000rpm for 3 minutes. Remove and freeze for 5 minutes. Add 6% diluent and 0.2% pigment and mix for 3 minutes. After mixing, freeze in a refrigerator for 5 minutes. Repeat the mixing and freezing process twice to ensure thorough mixing. After mixing, pour into a syringe and mix in a mixer at 3000rpm for 3 minutes to remove bubbles.

[0117] A stainless steel needle with an inner diameter of 340 μm and an exposed needle length of 25.4 mm was installed on the syringe. The printing pressure was set to 80 psi, the printing speed to 1 mm / s, and the printing depth to 10 mm. The printing was performed in baking soda solid.

[0118] Place the container containing baking soda in an 80℃ oven to cure for 6 hours.

[0119] Prepare a 0.1 mol / L dilute hydrochloric acid solution, put the printed part into it and stir for 48 hours, then soak it in hot water for 48 hours, changing the water as needed. After soaking, rinse the sample with distilled water 3-5 times to remove any residual solution on the surface, and finally place the sample in an 80℃ oven to dry for 12 hours.

[0120] In this implementation case, the obtained printing filament linewidth was 679.4 μm.

[0121] Example 3

[0122] Weigh 5g of SE1700 main agent, add 1wt% retarder, and mix in a planetary mixer at 3000rpm for 3 minutes. Cool in a refrigerator for 5 minutes. Add 0.5g of SE1700 curing agent and mix at 3000rpm for 3 minutes. Remove and freeze for 5 minutes. Add 6% diluent and 0.2% pigment and mix for 3 minutes. After mixing, freeze in a refrigerator for 5 minutes. Repeat the mixing and freezing process twice to ensure thorough mixing. After mixing, pour into a syringe and mix in a mixer at 3000rpm for 3 minutes to remove bubbles.

[0123] A stainless steel needle with an inner diameter of 340 μm and an exposed needle length of 25.4 mm was installed on the syringe. The printing pressure was set to 80 psi, the printing speed to 3 mm / s, and the printing depth to 10 mm. The printing was performed in baking soda solid.

[0124] Place the container containing baking soda in an 80℃ oven to cure for 6 hours.

[0125] Prepare a 0.1 mol / L dilute hydrochloric acid solution, put the printed part into it and stir for 48 hours, then soak it in hot water for 48 hours, changing the water as needed. After soaking, rinse the sample with distilled water 3-5 times to remove any residual solution on the surface, and finally place the sample in an 80℃ oven to dry for 12 hours.

[0126] In this implementation case, the obtained printing filament linewidth was 378.7 μm.

[0127] Example 4

[0128] Weigh 5g of SE1700 main agent, add 1wt% retarder, and mix in a planetary mixer at 3000rpm for 3 minutes. Cool in a refrigerator for 5 minutes. Add 0.5g of SE1700 curing agent and mix at 3000rpm for 3 minutes. Remove and freeze for 5 minutes. Add 6% diluent and 0.2% pigment and mix for 3 minutes. After mixing, freeze in a refrigerator for 5 minutes. Repeat the mixing and freezing process twice to ensure thorough mixing. After mixing, pour into a syringe and mix in a mixer at 3000rpm for 3 minutes to remove bubbles.

[0129] A stainless steel needle with an inner diameter of 420 μm and an exposed needle length of 38 mm was installed on a syringe. The printing pressure was set to 70 psi, the printing speed to 1 mm / s, and the printing depth to 10 mm. The printing was performed in baking soda solid.

[0130] Place the container containing baking soda in an 80℃ oven to cure for 6 hours.

[0131] Prepare a 0.1 mol / L dilute hydrochloric acid solution, put the printed part into it and stir for 48 hours, then soak it in hot water for 48 hours, changing the water as needed. After soaking, rinse the sample with distilled water 3-5 times to remove any residual solution on the surface, and finally place the sample in an 80℃ oven to dry for 12 hours.

[0132] In this implementation case, the obtained printing filament linewidth is 515.8 μm.

[0133] Example 5

[0134] Weigh 5g of SE1700 main agent, add 1wt% retarder, and mix in a planetary mixer at 3000rpm for 3 minutes. Cool in a refrigerator for 5 minutes. Add 0.5g of SE1700 curing agent and mix at 3000rpm for 3 minutes. Remove and freeze for 5 minutes. Add 6% diluent and 0.2% pigment and mix for 3 minutes. After mixing, freeze in a refrigerator for 5 minutes. Repeat the mixing and freezing process twice to ensure thorough mixing. After mixing, pour into a syringe and mix in a mixer at 3000rpm for 3 minutes to remove bubbles.

[0135] A stainless steel needle with an inner diameter of 420 μm and an exposed needle length of 38 mm was installed on a syringe. The printing pressure was set to 70 psi, the printing speed to 1 mm / s, and the printing depth to 30 mm. The printing was performed in baking soda solid.

[0136] Place the container containing baking soda in an 80℃ oven to cure for 6 hours.

[0137] Prepare a 0.1 mol / L dilute hydrochloric acid solution, put the printed part into it and stir for 48 hours, then soak it in hot water for 48 hours, changing the water as needed. After soaking, rinse the sample with distilled water 3-5 times to remove any residual solution on the surface, and finally place the sample in an 80℃ oven to dry for 12 hours.

[0138] In this implementation case, the obtained printed filament linewidth was 508.8 μm.

[0139] Example 6

[0140] A print head with an inner diameter of 0.34 mm and an exposed length of 25.4 mm was selected. The printing pressure was 55 psi and the printing speed was 1 mm / s when printing SE1700 + 6 wt% Thinner ink. The printing pressure was 20 psi and the printing speed was 3 mm / s when printing Ecoflex0030 ink. Surface solids were washed away after curing. Figure 8 These are cross-sectional electron microscope images of the printed lines from two different inks, with linewidths of 363.1 μm and 420.8 μm, respectively. The SE1700+6wt% Thinner filament has a solid internal structure with micron-sized pores on the periphery. The Ecoflex0030 filament, on the other hand, is riddled with pores. This indicates that baking soda particles penetrate the interior of the filament during the printing process. This result more clearly shows that solid particles cannot penetrate the interior of inks with yield strength, but are instead embedded on the ink surface; while solid particles are more likely to penetrate inks without yield strength, and the lower the viscosity, the more pronounced the mutual wetting between the ink and solid particles.

[0141] The foregoing description illustrates and describes several preferred embodiments of the present invention. However, as previously stated, it should be understood that the present invention is not limited to the forms disclosed herein and should not be construed as excluding other embodiments. It can be used in various other combinations, modifications, and environments, and can be altered within the scope of the inventive concept described herein through the foregoing teachings or techniques or knowledge in related fields. Any modifications and variations made by those skilled in the art that do not depart from the spirit and scope of the present invention should be within the protection scope of the appended claims.

Claims

1. A method for solid support bath-assisted 3D printing, characterized in that, Includes the following steps: S1. Formulating a silicone elastomer ink, wherein the silicone elastomer ink is a silicone elastomer ink with yielding behavior, comprising PDMS silicone rubber, silicone diluent, retarder and pigment; or is a silicone elastomer ink without yielding behavior, comprising PDMS silicone rubber and retarder; The preparation steps of the silicone elastomer ink with yielding behavior include: S111. PDMS silicone rubber is mixed with 1 wt% retarder and then cooled to obtain the first mixture; S112. Add a curing agent to the first mixture, then mix and cool to obtain a second mixture; S113. Add 6 wt% diluent and 0.2 wt% pigment to the second mixture, mix, and cool to obtain silicone elastomer ink; S2. Load the silicone elastomer ink into a printing syringe and print according to the set printing requirements in a container containing a solid matrix with a certain particle size or angle of repose. The solid matrix with a certain particle size is polytetrafluoroethylene solid, magnetic powder, or carbon nanotubes, and the particle size is less than or equal to 1000 micrometers. The inherent density of the solid matrix is ​​greater than 0.5 g / cm³. 3 And simultaneously less than 10g / cm 3 The angle of repose is less than 50°, and the selected solid matrix with an angle of repose is: baking soda with an angle of repose of 41.4°, white sugar with an angle of repose of 39.3°, salt with an angle of repose of 39.1°, hollow glass microspheres with an angle of repose of 34.4°, 300-mesh sand with an angle of repose of 42.8°, or 200-mesh sand with an angle of repose of 34.7°. S3. After printing, heat the container containing the solid matrix for a certain period of time; S4. Remove the semi-cured printed part and heat it further to obtain a fully cured printed component.

2. The method according to claim 1, characterized in that, S2 includes: S2.

1. Fix the syringe containing silicone elastomer ink above the printing platform, and at the same time fix the container containing solid particle matrix on the printing platform; S2.

2. Adjust the position of the syringe needle relative to the container, adjust the printing speed, printing pressure, and printing depth, and complete the printing of silicone elastomer ink in the container according to the set printing requirements.

3. The method according to claim 2, characterized in that, For printing silicone elastomer inks with yield stress, the printing depth is 10–30 mm, the printing pressure is 50–80 psi, and the printing speed is 1–3 mm / s; for printing silicone elastomer inks without yield behavior, the printing pressure is 20 psi, the printing speed is 1–5 mm / s, and the printing depth is 10 mm.

4. The method according to claim 3, characterized in that, The linewidth of the printed component ranges from 342.5 to 679.4 µm.

5. A printed component, characterized in that, The printed component is prepared by the method described in any one of claims 1-4.

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