Method and product for assisting 3D printing based on solid support bath

Abstract

The invention relates to a method for assisting 3D printing based on a solid support bath and a product. The method comprises the following steps: preparing silicone elastomer ink; filling the silicone elastomer ink into a printing needle cylinder, and printing in a container containing a solid matrix with a certain particle size or repose angle according to a set printing requirement; after printing is completed, the whole container is heated for a certain time; and taking out the semi-cured printing piece, and continuously heating to obtain a completely-cured printing component. According to the method, the selection range of printing ink is expanded, printing can be conducted in solid particles or matrixes with different particle sizes or repose angles, and by adjusting printing parameters, a complex three-dimensional structure can be obtained through printing by adopting simple printing equipment only under the supporting effect of the solid particle matrixes; and a printing component can be obtained through simple post-treatment.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to a method and product based on solid support bath assisted 3D printing. Background Art

[0002] At present, with the rapid development of flexible wearable devices, soft robots, and health and medical equipment, the preparation and research of soft materials have attracted great attention from scientific researchers. Among them, silicone elastomers have been widely studied due to their good thermal stability, chemical resistance, and mechanical compliance. However, the traditional molding process of silicone elastomers, template casting molding, often has the problem of low efficiency, and also has the limitations of simple structure and single function. 3D printing technology is a customizable technology that can realize complex structural design. Its emergence is conducive to the molding of soft materials. In 3D printing technology, direct ink writing (DIW) is a printing technology based on material extrusion, which has the most diverse printing materials, such as liquid crystal elastomers, hydrogels, elastic polymers, etc. For direct ink writing technology, the ink material only needs to meet the printability to be printed. Therefore, in DIW technology, the ink material can be customized according to the required function. In order to achieve DIW printing of silicone elastomers, researchers will add rheology modifiers or fillers to silicone elastomers to make them have shear thinning and shear yield characteristics, but this will inevitably change the performance of the silicone elastomer material itself. At the same time, adding too much filler will cause needle clogging and uneven mixing. Therefore, researchers have proposed an embedding 3D printing technology, in which the support bath plays a supporting role to solve the problems caused by the high content of ink fillers. However, this method has certain difficulties in the preparation of multi-material and multi-functional complex components. There are also related reports proposing to install a Joule heater at the printing nozzle to quickly complete the printing and curing of silicone elastomer materials, but this poses the problem of equipment modification. Based on the above problems, the invention proposes to print silicone elastomers in a solid matrix, and the solid matrix serves as a support to achieve 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, comprising the following steps:

[0005] S1. Prepare silicone elastomer ink;

[0006] S2. The silicone elastomer ink is loaded into a printing syringe and printed in a container containing a solid matrix having a particle size or a repose angle of a certain size according to the set printing requirements;

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

[0008] S4. The semi-cured printed part is taken out and further heated to obtain a fully cured printed part.

[0009] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the silicone elastomer ink comprises PDMS silicone rubber, a silicone diluent and a retarder, or comprises PDMS silicone rubber and a retarder.

[0010] According to the above aspects and any possible implementation, an implementation is further provided, wherein the preparation steps of the silicone elastomer ink include:

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

[0012] S112. Adding a curing agent to the first mixture, mixing and cooling, to obtain a second mixture;

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

[0014] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the particle size is less than or equal to 1000 microns.

[0015] According to the above aspects and any possible implementation, an implementation is further provided, wherein S2 comprises: S2.1. fixing a syringe filled with silicone elastomer ink above a printing platform, and fixing a container containing a solid particle matrix on the printing platform;

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

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

[0018] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the repose angle is less than 50°.

[0019] According to the above aspects and any possible implementation, an implementation is further provided, wherein the solid matrix with particle size is polytetrafluoroethylene solid, magnetic powder or carbon nanotubes, and the solid matrix with repose angle is baking soda, sugar, salt, sand or glass beads.

[0020] According to the above aspects and any possible implementation, there is further provided an implementation, wherein the line width of the printed component ranges from 342.5 to 679.4 μm.

[0021] The present invention also provides a printing component, and the printing component is prepared by using the method.

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

[0023] The method of solid support bath assisted 3D printing of the present invention comprises: preparing silicone elastomer ink; loading the silicone elastomer ink into a printing syringe, and printing in a container containing a solid matrix with a certain particle size or repose angle according to the set printing requirements; after printing is completed, heating the container containing the solid matrix for a certain time; taking out the heated semi-cured print, and further heating to obtain a fully cured printed component. The method of the present invention expands the selection range of printing ink, and the printing equipment is simple. Complex three-dimensional structures can be printed only under the support of the solid particle matrix, and the components can be obtained after simple post-processing. In the present invention, the solid matrix plays the role of supporting the ink material to realize the printing of the structure with a wide top and a narrow bottom and a three-dimensional structure composed of lines, and the post-processing operation of the printed structure is simple. In addition, the solid matrix can be recycled. The present invention can also realize the printing of ink without yield stress, reduce the rheological requirements of the printing ink material, and realize printing in a functional solid matrix at the same time, giving the silicone elastomer different functionalities, and providing the possibility of printing more functional solid matrices. BRIEF DESCRIPTION OF THE DRAWINGS

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

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

[0026] Figure 3 It is the rheological properties diagram of two silicone elastomer ink materials.

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

[0028] Figure 5 Schematic diagram of the angle of repose of different solid matrix powders.

[0029] Figure 6 This is a real picture of the lines printed by Ecoflex0030 printing ink at 20psi pressure.

[0030] Figure 7 These are the surface and cross-sectional morphologies of lines printed with SE1700+6% Thinner and Ecoflex0030 inks in glass microbeads.

[0031] Figure 8 This is a scanning electron microscope image of the cross-section of silicone elastomer printed filaments prepared by printing with SE1700+6% Thinner and Ecoflex0030 inks in a baking soda support bath.

[0032] Fig. 9 The figures are the printing filament sizes and microscope images of the SE1700+6% Thinner printing ink of the present invention at different printing pressures at a printing speed of 1 mm / s.

[0033] Fig.10 The relationship between the size and theoretical diameter of the printed filament under different pressures of SE1700+6% Thinner printing ink, the relationship between the y / x value and the printing pressure, and the electron microscope image of the printed filament cross section.

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

[0035] Fig.12 The figure shows the relationship between the y / x value of the printed filament and the printing speed of the SE1700+6% Thinner printing ink at different printing speeds and the electron microscope picture of the cross section of the printed filament.

[0036] Fig.13 It is the printing filament size of SE1700+6% Thinner printing ink at different printing depths.

[0037] Fig.14 Schematic diagram of the printing path of Ecoflex0030 ink, including: (a) schematic diagram of the trapezoidal path; (b) actual printing picture; (c) normal closed path and pattern photo printed in baking soda; (d) improved path and pattern photo printed in baking soda.

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

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

[0040] Fig.17 The film is printed by SE1700+6% Thinner printing ink in baking soda solid for triboelectric power generation. DETAILED DESCRIPTION

[0041] In order to better understand the technical solution of the present invention, the content of the present invention includes but is not limited to the specific implementation methods described below, and similar technologies and methods should be considered to be within the scope of protection of the present invention. In order to make the technical problems, technical solutions and advantages to be solved by the present invention clearer, the following will be described in detail with reference to the accompanying drawings and specific embodiments.

[0042] It should be clear that the embodiments described in the present invention are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0043] The terms used in the embodiments of the present invention are only for the purpose of describing specific embodiments, and are not intended to limit the present invention. The singular forms "a", "said" and "the" used in the embodiments of the present invention and the appended claims are also intended to include plural forms, unless the context clearly indicates other meanings.

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

[0045] S1. Prepare silicone elastomer ink;

[0046] S2. The silicone elastomer ink is loaded into a printing syringe and printed in a container containing a solid matrix having a particle size or a repose angle of a certain size according to the set printing requirements;

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

[0048] S4. The semi-cured printed part is taken out and further heated to obtain a fully cured printed part.

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

[0050] Preferably, the silicone elastomer ink is a silicone elastomer ink with yield stress, including Dow Corning SE1700 model PDMS silicone rubber, Silicone Thinner, retarder and pigment from Smooth-On Company of the United States; or it is a silicone elastomer ink without yield behavior, which includes: Ecoflex0030 model PDMS silicone rubber and retarder from Smooth-On Company of the United States.

[0051] Preferably, the preparation steps of the silicone elastomer ink having yielding behavior include:

[0052] S111. The SE1700 main agent and 1 wt% retarder are mixed and cooled to obtain a first mixture;

[0053] S112. Adding SE1700 curing agent to the first mixture, mixing and cooling to obtain a second mixture;

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

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

[0056] S121. The B component of the PDMS silicone rubber Ecoflex0030 model of Smooth-On Company of the United States was mixed with 1wt% of a retarder and then cooled to obtain a first cooling material;

[0057] S122. Add component A of Ecoflex0030 to the first cooled material, mix again, and cool to obtain a silicone elastomer ink without yielding behavior.

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

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

[0060] Preferably, the printing depth of printing 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 printing 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 beads, polytetrafluoroethylene solid, magnetic powder or carbon nanotubes.

[0062] As an embodiment disclosed by the present invention, the present invention further provides a printing component, which is prepared by the method described in the present invention, wherein the width range of the printing wire of the printing component is 342.5 to 679.4 μm.

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

[0064] The method of the present invention is first implemented from the preparation of ink. Two silicone elastomers, BASF SE1700 PDMS silicone rubber and American Smooth-On Ecoflex0030 PDMS silicone rubber, are selected as ink materials, wherein SE1700+6% silicone diluent represents a fluid with shear thinning characteristics and yield stress, and Ecoflex0030 is a Newtonian fluid, representing a fluid without shear thinning and yield stress. Shear thinning is manifested as the viscosity of the ink material decreases with the increase of the shear rate, so that the ink is smoothly squeezed out of the nozzle. The existence of yield stress reflects the process of ink being squeezed out from the needle to being deposited on the substrate. When the shear force is less than the yield stress, the storage modulus of the ink material is greater than the loss modulus, showing solid-like behavior. When the shear stress is greater than the yield stress, the loss modulus is greater than the storage modulus, showing liquid-like behavior. SE1700 is a silicone elastomer with 20% fumed silica added. The purpose of adding 6% silicone diluent is to reduce the yield stress, so that the rheological requirements of the printing ink are lower and more universal. For Ecoflex0030 silicone elastomer, its loss modulus is always greater than the storage modulus, showing liquid behavior, and therefore cannot be printed in air.

[0065] Then, the present invention verifies the printability of the printing ink Ecoflex0030 in a baking soda matrix and the influence of the printing pressure, printing speed and printing depth on the size and morphology of the printed component when the printing ink SE1700+6% Thinner is printed in a baking soda solid matrix.

[0066] Furthermore, the present invention solves the problem of difficult closing of shapes 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 the design of the path.

[0067] Finally, the present invention demonstrates printing in baking soda solid and polytetrafluoroethylene solid, magnetic powder, and carbon nanotubes, providing ideas for printing in more solid matrices.

[0068] The present invention is implemented by the following technical solutions:

[0069] 1) Preparation of silicone ink materials

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

[0071] First, 5g of SE1700 main agent and 1wt% of retarder were mixed in a planetary mixer at 3000rpm for 3 minutes, and then placed in a -35℃ refrigerator for 5 minutes;

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

[0073] Finally, 6 wt % Thinner diluent was added to the cooled material, mixed again at a rotation speed of 3000 rpm for 3 minutes, and cooled again for 5 minutes to obtain SE1700 ink.

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

[0075] First, 3 g of Ecoflex 0030 (Part B) and 1 wt % of polymerization inhibitor were mixed in a planetary mixer at 3000 rpm for 3 minutes, and then placed in a -35°C refrigerator for cooling for 5 minutes.

[0076] To the cooled material, 3 g of Ecoflex 0030 (Part A) and 0.2 wt % of pigment were added and mixed for 3 minutes, followed by cooling for 5 minutes to obtain Ecoflex 0030 ink.

[0077] 2) Selected solid matrix

[0078] The solid matrix used in the present invention has a certain particle size or a certain angle of repose, such as Figure 5 As shown, the angle of repose of solid matrix powder is used to characterize the fluidity of powder. The angle of repose refers to the tangent value of the angle between the solid particles and the horizontal plane when they reach equilibrium on the inclined plane. The larger the angle of repose, the more difficult it is for the particles to flow. Specifically, the present invention selects a solid matrix with an angle of repose less than 50°. A solid matrix less than this angle indicates that the solid fluidity is good and is suitable for printing. The present invention selects baking soda, white sugar, salt, sand or glass beads of a certain mesh number as a solid matrix, wherein the angle of repose of baking soda is 41.4°, the angle of repose of white sugar is 39.3°, the angle of repose of salt is 39.1°, the angle of repose of hollow glass beads is 34.4°, the angle of repose of 300 mesh sand is 42.8°, and the angle of repose of 200 mesh sand is 34.7°.

[0079] The solid particle size of a certain size is required to be less than or equal to 1000 microns. If the particle size is too large, there will be steric hindrance between the solid matrix, resulting in too large pores between the particles, thereby reducing the support for the ink. The inherent density of the solid matrix is ​​greater than 0.5g / cm 3 And at the same time less than 10g / cm 3 , the state of the solid when printing in the container, that is, when the needle tip is inserted into the solid particles to squeeze out the ink, if the density of the solid matrix is ​​too small, the solid matrix is ​​too light and can be easily carried away by the printing needle; if the density of the solid matrix is ​​too large, the ink will be squeezed to cause it to deform and break. Based on the above requirements, the present invention selects polytetrafluoroethylene solid, magnetic powder or carbon nanotubes for printing.

[0080] In addition, the contact angle formed by the baking soda, sugar, salt, sand or glass beads, polytetrafluoroethylene solid, magnetic powder or carbon nanotube mentioned above when in contact with Ecoflex0030 ink is less than 60°. The contact angle indicates the compatibility between solid and liquid. This angle also indicates that the above solid matrix meets the printing requirements, such as Figure 4 Shown are the contact angles of different solid substrates with Ecoflex0030 ink, which is used to characterize the diffusion behavior between the ink material and the solid.

[0081] The contact angle of Ecoflex0030 ink droplets on different solid surfaces (powder pressed into sheets) changes over time. The ink shows spreading behavior, and solid substrates with contact angles between 20 and 40° are preferred for printing. The contact angle of Ecoflex0030 ink with hollow glass microbeads and sand is relatively high, about 40°, followed by baking soda, salt and polytetrafluoroethylene PTFE, with contact angles of about 30°. The least wettable is white sugar, about 20°.

[0082] 3) Build a printing system and print

[0083] like Figure 1 As shown, in the printing system adopted by the present invention, a container containing a solid matrix is ​​placed on a workbench of a glue dispenser, and an X-axis, a Y-axis and a Z-axis are arranged at one corner of the workbench. A printing syringe is arranged above the workbench, and a printing needle is arranged at the front end thereof, and a pressure controller is connected at the other end thereof for controlling the gas pressure supplied to the printing syringe by the air pump. The glue dispenser is respectively connected to the pressure controller and a PC computer, and the printing mode in the container is controlled under the control of the PC computer, and the printing speed and printing depth can be set according to the pre-designed requirements.

[0084] During printing, first fix the syringe containing the ink material prepared in step 1) on the workbench of the glue dispenser, and then place the container containing the solid matrix on the workbench, determine the printing starting point by controlling the X-axis and Y-axis of the printer work platform, and control the depth of the syringe from the solid surface by adjusting the Z-axis. During the printing process, according to the set printing requirements, the printing pressure is adjusted by controlling the pressure controller, the printing parameters of the glue dispenser such as the printing speed are controlled by the PC, and the movement of the glue dispenser is controlled and the printing path is designed. When the SE1700+6% Thinner ink is used in the present invention, the exposed length of the printing needle is 25.4mm and the inner diameter is 0.34mm. The printing needle of this size can meet the printing pressure and printing speed range to realize the printing of continuous printing components. Preferably, the present invention uses a printing needle with an exposed length of 38mm and an inner diameter of 0.42mm to achieve printing at different printing depths, with a printing pressure of 50-80psi, a printing speed of 1-3mm / s, and a printing depth of 10-30mm. The present invention uses the line width of the printed components at the above five different depths, such as Fig.12 As shown in the figure, the line widths are 515.8 μm, 503.1 μm, 503.0 μm, 497.0 μm and 508.8 μm respectively. The line width of the printed component does not change significantly, indicating that within this range, the printing depth has no significant effect on the line width of the printed component.

[0085] The present invention uses Ecoflex0030 ink to print with a printing needle having 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 to 3 mm / s. The printed component obtained is as follows Figure 6 shown.

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

[0087] When the SE1700+6% Thinner ink is at a pressure of 50-80psi and a printing speed of 1-3mm / s, the line width of the printed components is in the range of 342.5-679.4μm, and the y / x value is from 0.7122 to 0.8093; when the printing depth is 10-30mm, the line width 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] The present invention realizes this by printing in solids such as baking soda, carbon nanotubes, polytetrafluoroethylene, and Fe3O4 magnetic powder. After removing the baking soda on the surface, the printed component obtained by printing with baking soda has pits left on the surface of the printed component where the baking soda particles attach. These pits increase the surface roughness of the printed component and can be used to increase the triboelectric output. The printed component obtained by printing with carbon nanotubes has carbon nanotubes attached to its surface that can make the printed component conductive and can be used for sensing. The printed component obtained by printing with polytetrafluoroethylene has improved surface hydrophobicity of the printed component because polytetrafluoroethylene is a hydrophobic material. The use of Fe3O4 magnetic powder enables the obtained printed component to have a magnetic intelligent response. The present invention prepares two silicone elastomer inks, one of which is SE1700+6% Thinner and the other is Ecoflex0030. Figure 2 It is a solid matrix assisted ink direct writing process. Figure 3 The rheological properties of two silicone elastomer ink materials show that SE1700+6% Thinner ink has a yield stress point (intersection point). Before the yield stress point, the storage modulus of the ink material is greater than the loss modulus, showing solid-like behavior. After the yield point, the loss modulus is greater than the storage modulus, showing liquid-like behavior. For the Ecoflex0030 ink material, the loss modulus is always greater than the storage modulus, and there is no yield stress. These two inks are not printable when used in air, but by using the above-mentioned solid matrix provided by the present invention, printing with the two inks can be achieved. Both inks can be printed in glass microspheres, and a needle with an inner diameter of 0.52mm is selected to print large-diameter printed components. Transparent glass microspheres with a particle size range of 200-400μm are used as a solid support bath. After curing, the printed component is placed under a camera to observe the surface morphology, and the lines of the printed component are cut to observe its cross-sectional morphology. Figure 7 It is the corresponding optical photo, and each small grid in the figure represents 1mm. It can be seen from Figures a1 and d1 that the surface of the silicone rubber is covered with glass balls, and the thickness of the printing filament of Ecoflex0030 is obviously uneven. The printing filament obtained by using SE1700+6wt% Thinner can be seen to have a boundary between the ink and the solid, and the solid is combined with the ink in the form of an inlay. In Figures a2 and d2, the glass balls exist in the form of entering the interior of the Ecoflex0030 ink, unlike the SE1700+6wt% Thinner ink printing filament, which has a clear boundary. In addition, by increasing the printing speed, the size of the printed line becomes smaller. By observing the cross-section of the printed line of different inks, there is still a boundary between the SE1700+6wt% Thinner ink and the glass balls in Figure a3, and there are more glass balls in Figure d3. It shows that in the printing technology provided by the present invention, the rheological properties of the ink have a significant effect on the final printed filament.

[0090] That is, the present invention adopts the above-prepared silicone elastomer ink to construct a complex structure through solid particle matrix assisted 3D printing, and the method specifically includes the following steps:

[0091] S1) preparing silicone elastomer ink;

[0092] S2) constructing a printing system, loading the above printing ink into a syringe and printing on a solid matrix;

[0093] S3) placing the container printed with the semi-cured ink and the solid matrix into an oven at 80° C. for curing for 6 hours;

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

[0095] The specific steps of S2) are:

[0096] S2.1) Fix the syringe containing ink material on the dispensing machine workbench, place the container containing solid matrix on the workbench, and determine the printing starting point by controlling the X-axis and Y-axis.

[0097] S2.2) Regulate 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 the S2.2), when printing SE1700+6% Thinner ink, the printing depth is 10-30 mm, the printing pressure is 50-80 psi, and the printing speed is 1-3 mm / s; when printing Ecoflex0030 ink, the printing pressure is 20 psi, the printing speed is 1-5 mm / s, and the printing depth is 10 mm.

[0099] The post-processing steps in S4) are:

[0100] The treatment method for baking soda solids is to place the printed component in 0.1mol / L dilute hydrochloric acid and stir for 48 hours, then soak it in hot water for 48 hours, change the water, rinse the printed component with distilled water 3 to 5 times after soaking to remove the residual solution on the surface, and finally place the sample in an 80℃ oven to dry for 12 hours. For other insoluble solid matrices used, first use a dust gun to blow off the solids on the surface of the printed component, then put it in ethanol for ultrasonic treatment for 6 hours, then rinse the sample with distilled water 3 to 5 times, and finally dry it.

[0101] The method achieves printing using Ecoflex0030 ink, such as Figure 6The printed filaments of SE1700+6% Thinner ink obtained by this method at a printing speed of 1 mm / s and a printing pressure of 50 to 80 psi are as shown in FIG. Figure 8 As shown, the printing wire width increases with the increase of pressure, and the value is 342.5~679.4μm. Fig. 9 The printed filament size and microscope images under different printing pressures when the SE1700+6% Thinner printing ink is printed at a printing speed of 1mm / s. Fig.10 The relationship between the size and theoretical diameter of the printed filament under different pressures of SE1700+6% Thinner printing ink, the relationship between the y / x value and the printing pressure, and the electron microscope image of the printed filament cross section. Fig.10 a is the relationship between its characteristic size and theoretical diameter. When the pressure is 80psi, the printed wire width deviates the most from the theoretical value. Fig.10 In b, the cross-sectional width of the printed wire is x, the cross-sectional height is y, and the y / x value 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-sectional deviation from the circle is more obvious. Fig.10 c is an electron microscope image of the corresponding cross section of the printing filament. The printing filament obtained by the present invention is in the shape of a "steamed bun", with a bulge on the 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, so the bottom is relatively flat. Fig.11 This is the effect of printing speed on the size of the printing filament under a printing pressure of 80 psi. The higher the printing speed, the smaller the line width of the printing filament. When the printing speed increases from 1 mm / s to 3 mm / s, the line width of the printing filament decreases from 679.4 μm to 378.7 μm due to the stretching of the printing filament. Fig.12 The corresponding y / x value of the printing filament and the electron microscope image of the cross section show that the faster the printing speed, the closer y / x is to 1, the thinner the printing filament, and the closer the cross section is to a circle. Fig.13 This is the line width of the printed filament of SE1700+6% Thinner printing ink at different printing depths. It can be seen that at different printing depths, the printed line width does not change much.

[0102] To improve the printing path of Ecoflex0030 ink, place a container containing baking soda close to the container wall but not close to the wall (there is still solid between the needle and the container wall), add a small amount of Ecoflex0030 ink with luminous powder along the container wall, and print at a pressure of 20psi. Fig.14 (a) in the figure shows a trapezoidal pattern printed at speeds of 1 mm / s, 2 mm / s, and 3 mm / s, respectively. Fig.14In (b), the starting point and the end point cannot overlap, and the faster the printing speed, the harder it is to close the pattern. This is mainly because after the printing is completed, the needle will be lifted up and leave with the ink at the end point, resulting in the pattern being unable to close. In order to eliminate the interference of the container wall on the printed pattern, the normal path was printed in baking soda solid at a speed of 1 mm / s and 2 mm / s respectively ( Fig.14 (c) in the figure, it is observed that the amount of ink is relatively small at the junction of the beginning and the end. Extend the last step path to ensure that the ink can intersect with the ink at the starting point ( Fig.14 (d) in the figure), and printed at 1 mm / s and 2 mm / s along the improved path in baking soda powder. The amount of ink at the junction of the improved path increased significantly ( Fig.14 (d) in the figure shows that the improvement of its path is beneficial to the integrity of the printed pattern.

[0103] According to the above method, the printing path of SE1700 ink was improved, and finally a 3D structure was prepared through path design. Fig.15 As shown, a triangular pyramid supported by a line was printed, which is different from the printing method of stacking layer by layer; at the same time, an inverted pyramid structure with a wide top and a narrow bottom was also printed, which is different from the conventional 3D printing method that can only print a narrow top and a wide bottom structure; and a cilia array structure can also be printed upright in the vertical direction. The printing of these multi-style structures benefits from the support of the solid matrix, and does not require any extra supporting parts to play a supporting role or to modify the printer. The printing method provided by the present invention is expected to achieve the printing of more sophisticated and complex structures that are difficult to achieve with other methods.

[0104] Based on this method, the present invention embeds functional solids on the surface of the printing filament, giving the printed structure the properties of a solid matrix. Fig.16 Shown here are silicone elastomer fibers printed in carbon nanotubes that can stretch and bend, with resistance changing as the fibers are stretched. Fig.17 The two-layer structure film printed in baking soda can be used for triboelectric power generation due to the increased surface roughness. The present invention squeezes the printing ink between the solid particles so that the surface of the printed component is embedded in the solid particles. The effect of this operation is that under the wrapping of the solid particles, the existing ink that cannot be printed in the air can be used to realize the printing operation in the solid matrix by this method.

[0105] The second function is that if solid particles with certain functionality are used for printing, a functional printed component composite material can be directly formed after printing. For example, the silicone rubber / Fe3O4 composite formed after the ink is printed in the iron powder has magnetism. SE1700+6% diluent is an ink with yield strength, which can be printed in the air using conventional printing methods. This method can be used to give the surface structure and functionality through surface solid particles.

[0106] Ecoflex00-30 is an ink without yield strength and cannot be printed in the air by conventional methods, but can be printed and formed by using this method.

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

[0108] The following is a specific example to illustrate

[0109] Example 1

[0110] Weigh 5g of SE1700 main agent, add 1wt% of retarder, mix at 3000rpm in a planetary mixer for 3 minutes, and put in a refrigerator to cool for 5 minutes. Then add 0.5g of SE1700 curing agent and mix at 3000rpm for 3 minutes, take out and freeze for 5 minutes, then add 6% of diluent and 0.2% of pigment and mix for 3 minutes, put in a refrigerator to freeze for 5 minutes after mixing, repeat the above mixing and freezing operations twice to mix evenly. After mixing, pour into a syringe, put into a mixer and mix at 3000rpm for 3 minutes to complete defoaming.

[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, and the printing pressure was set to 50 psi, the printing speed was 1 mm / s, the printing depth was 10 mm, and printing was performed in baking soda solid.

[0112] Place the container containing baking soda in an oven at 80°C for 6 hours.

[0113] Prepare dilute hydrochloric acid with a concentration of 0.1 mol / L, place the printed part in it and stir for 48 hours, then soak it in hot water for 48 hours. Remember to change the water. After soaking, rinse the sample with distilled water 3-5 times to remove the residual solution on the surface, and finally place the sample in an 80°C oven to dry for 12 hours.

[0114] In this implementation case, the obtained printed wire width is 342.5 μm.

[0115] Example 2

[0116] Weigh 5g of SE1700 main agent, add 1wt% of retarder, mix at 3000rpm in a planetary mixer for 3 minutes, and put in a refrigerator to cool for 5 minutes. Then add 0.5g of SE1700 curing agent and mix at 3000rpm for 3 minutes, take out and freeze for 5 minutes, then add 6% of diluent and 0.2% of pigment and mix for 3 minutes, put in a refrigerator to freeze for 5 minutes after mixing, repeat the above mixing and freezing operations twice to mix evenly. After mixing, pour into a syringe, put into a mixer and mix at 3000rpm for 3 minutes to complete defoaming.

[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, and the printing pressure was set to 80 psi, the printing speed was 1 mm / s, the printing depth was 10 mm, and printing was performed in baking soda solid.

[0118] Place the container containing baking soda in an oven at 80°C for 6 hours.

[0119] Prepare dilute hydrochloric acid with a concentration of 0.1 mol / L, place the printed part in it and stir for 48 hours, then soak it in hot water for 48 hours. Remember to change the water. After soaking, rinse the sample with distilled water 3-5 times to remove the residual solution on the surface, and finally place the sample in an 80°C oven to dry for 12 hours.

[0120] In this implementation case, the obtained printed wire width is 679.4 μm.

[0121] Example 3

[0122] Weigh 5g of SE1700 main agent, add 1wt% of retarder, mix at 3000rpm in a planetary mixer for 3 minutes, and put in a refrigerator to cool for 5 minutes. Then add 0.5g of SE1700 curing agent and mix at 3000rpm for 3 minutes, take out and freeze for 5 minutes, then add 6% of diluent and 0.2% of pigment and mix for 3 minutes, put in a refrigerator to freeze for 5 minutes after mixing, repeat the above mixing and freezing operations twice to mix evenly. After mixing, pour into a syringe, put into a mixer and mix at 3000rpm for 3 minutes to complete defoaming.

[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, and the printing pressure was set to 80 psi, the printing speed was 3 mm / s, the printing depth was 10 mm, and printing was performed in baking soda solid.

[0124] Place the container containing baking soda in an oven at 80°C for 6 hours.

[0125] Prepare dilute hydrochloric acid with a concentration of 0.1 mol / L, place the printed part in it and stir for 48 hours, then soak it in hot water for 48 hours. Remember to change the water. After soaking, rinse the sample with distilled water 3-5 times to remove the residual solution on the surface, and finally place the sample in an 80°C oven to dry for 12 hours.

[0126] In this implementation case, the obtained printed wire width is 378.7 μm.

[0127] Example 4

[0128] Weigh 5g of SE1700 main agent, add 1wt% of retarder, mix at 3000rpm in a planetary mixer for 3 minutes, and put in a refrigerator to cool for 5 minutes. Then add 0.5g of SE1700 curing agent and mix at 3000rpm for 3 minutes, take out and freeze for 5 minutes, then add 6% of diluent and 0.2% of pigment and mix for 3 minutes, put in a refrigerator to freeze for 5 minutes after mixing, repeat the above mixing and freezing operations twice to mix evenly. After mixing, pour into a syringe, put into a mixer and mix at 3000rpm for 3 minutes to complete defoaming.

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

[0130] Place the container containing baking soda in an oven at 80°C for 6 hours.

[0131] Prepare dilute hydrochloric acid with a concentration of 0.1 mol / L, place the printed part in it and stir for 48 hours, then soak it in hot water for 48 hours. Remember to change the water. After soaking, rinse the sample with distilled water 3-5 times to remove the residual solution on the surface, and finally place the sample in an 80°C oven to dry for 12 hours.

[0132] In this implementation case, the obtained printed wire width is 515.8 μm.

[0133] Example 5

[0134] Weigh 5g of SE1700 main agent, add 1wt% of retarder, mix at 3000rpm in a planetary mixer for 3 minutes, and put in a refrigerator to cool for 5 minutes. Then add 0.5g of SE1700 curing agent and mix at 3000rpm for 3 minutes, take out and freeze for 5 minutes, then add 6% of diluent and 0.2% of pigment and mix for 3 minutes, put in a refrigerator to freeze for 5 minutes after mixing, repeat the above mixing and freezing operations twice to mix evenly. After mixing, pour into a syringe, put into a mixer and mix at 3000rpm for 3 minutes to complete defoaming.

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

[0136] Place the container containing baking soda in an oven at 80°C for 6 hours.

[0137] Prepare dilute hydrochloric acid with a concentration of 0.1 mol / L, place the printed part in it and stir for 48 hours, then soak it in hot water for 48 hours. Remember to change the water. After soaking, rinse the sample with distilled water 3-5 times to remove the residual solution on the surface, and finally place the sample in an 80°C oven to dry for 12 hours.

[0138] In this implementation case, the obtained printed wire width is 508.8 μm.

[0139] Example 6

[0140] A printing needle with an inner diameter of 0.34 mm and an exposed length of 25.4 mm was selected. The printing pressure when printing SE1700+6wt% Thinner ink was 55 psi and the printing speed was 1 mm / s. The printing pressure when printing Ecoflex0030 ink was 20 psi and the printing speed was 3 mm / s. After curing, the surface solid was washed off. Figure 8 These are cross-sectional electron microscope images of lines printed with two inks, with the printed wire widths being 363.1μm and 420.8μm, respectively. The interior of the SE1700+6wt% Thinner printed wire is a solid structure with micron-sized holes on the periphery. The interior of the Ecoflex0030 printed wire is full of holes. This indicates that baking soda particles entered the interior of the printed wire during the printing process. This result more intuitively shows that solid particles cannot enter the interior of the ink with yield strength, but are embedded in the surface of the ink; while solid particles are more likely to enter the ink without yield stress. The lower the viscosity, the more obvious the mutual infiltration of the ink and solid particles.

[0141] The above description shows and describes several preferred embodiments of the present invention, but as mentioned above, it should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the application concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not depart from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A method based on solid support bath assisted 3D printing, characterized in that: The steps include: S1. Prepare silicone elastomer ink; S2. The silicone elastomer ink is loaded into a printing syringe and printed in a container containing a solid matrix having a particle size or a repose angle of a certain size according to the set printing requirements; S3. After printing is completed, the container containing the solid matrix is ​​heated for a certain period of time; S4. Take out the semi-cured printed part, and further heat it to obtain a fully cured printed part.

2. The method according to claim 1, characterized in that The silicone elastomer ink comprises PDMS silicone rubber, a silicone diluent and a retarder, or comprises PDMS silicone rubber and a retarder.

3. The method according to claim 2, characterized in that The preparation steps of the silicone elastomer ink include: S111. The PDMS silicone rubber is mixed with 1 wt % of a retarder and then cooled to obtain a first mixture; S112. Adding a curing agent to the first mixture, mixing and cooling, to obtain a second mixture; S113. Add a diluent to the second mixture, mix, and cool to obtain silicone elastomer ink.

4. The method according to claim 1, characterized in that: The particle size is less than or equal to 1000 microns.

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

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

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

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

7. The method according to claim 4, characterized in that The angle of repose is less than 50°.

8. The method according to claim 7, characterized in that The solid matrix with a certain particle size is polytetrafluoroethylene solid, magnetic powder or carbon nanotube, and the solid matrix with a repose angle is baking soda, sugar, salt, sand or glass microbeads.

9. The method according to claim 6, characterized in that The line width of the printed component ranges from 342.5 to 679.4 μm.

10. A printing component, characterized in that: The printed component is prepared by the method according to any one of claims 1 to 9.

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