A post-processing process for two-photon polymerization additive manufacturing and 3D printed products

Abstract

The application discloses a kind of two-photon polymerization additive manufacturing post-processing process and 3D printing product, in above-mentioned post-processing process, 3D printing product is always in liquid environment before drying, 3D printing product is dried using low surface tension drying mode thereafter, reduce the surface tension of liquid when solution replacement in developing, fixing and solution volatilization in drying process possibly caused 3D printing product bending or degree of lodging, avoid the situation that the top of 3D printing product is pasted bottom.Generally speaking, after above-mentioned two steps, the large height-width ratio structure of 3D printing product still has certain degree of lodging, therefore, the technical scheme of the present application uses hot air gun to blow against the lodging direction of 3D printing product, so that the lodging part of 3D printing product restores upright state.Each step of above-mentioned post-processing process cooperates, guarantees that the 3D printing product with large height-width ratio does not appear structural failure problem in post-processing process.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of 3D printing, and particularly relates to a post-processing process of two-photon polymerization additive manufacturing and a 3D printing product. BACKGROUND

[0002] Two-photon polymerization additive manufacturing (or two-photon polymerization 3D printing) adopts nonlinear two-photon absorption, and the area of two-photon absorption inside a photosensitive material is limited to the focal spot of a light spot. The theoretical highest resolution can reach 200 nm, so that the two-photon polymerization 3D printing is the most precise one in the current 3D printing technology and occupies an absolute dominant position in high-precision micro-nano manufacturing.

[0003] However, when the two-photon polymerization 3D printing method is used to process a three-dimensional fragile structure (such as a large aspect ratio structure), the structure greatly affects the rigidity of the printed product, so that the printed product is prone to collapse and bending in the developing and drying processes due to the liquid tension of the developing liquid, thereby causing structural failure. SUMMARY

[0004] The application aims to provide a post-processing process of two-photon polymerization additive manufacturing and a 3D printing product. In the post-processing process, the 3D printing product is always immersed in a liquid environment before drying, so as to avoid structural failure caused by the surface tension of the liquid in the process of replacing the liquid reagent or drying.

[0005] The technical scheme of the application is as follows:

[0006] A post-processing process of two-photon polymerization additive manufacturing, two-photon polymerization additive manufacturing is used to print a 3D printing product on a substrate, and the 3D printing product has a large aspect ratio structure. The post-processing process comprises the following steps:

[0007] (1) immerse the 3D printing product and the substrate in a developing liquid, and after the 3D printing product is completely developed, replace the developing liquid with a fixing liquid, and stand still to fix the 3D printing product;

[0008] In step (1), the 3D printing product and the substrate are always immersed in a liquid environment.

[0009] (2) dry the 3D printing product and the substrate by using a low-surface-tension drying method;

[0010] (3) blow the 3D printing product with a hot air gun until the 3D printing product is straight, and the blowing direction is opposite to the direction of the 3D printing product.

[0011] In the above technical solution, the 3D printing product is always in a liquid environment before drying, and then a low-surface-tension drying method is used to dry the 3D printing product, thereby reducing the bending or lodging degree of the 3D printing product caused by the surface tension of the liquid during the replacement of the solution in the developing and fixing and the volatilization of the solution in the drying process, and avoiding the situation that the top of the 3D printing product is attached to the bottom. Generally, after the above two steps, the large height-width ratio structure of the 3D printing product will still have a certain degree of lodging, and therefore, the technical solution uses a hot air gun to blow against the lodging direction of the 3D printing product, so that the lodging part of the 3D printing product returns to an upright state.

[0012] In some possible implementations, the hot air gun comprises a hot air gun body, an adapter, and a hollow microneedle, and the air outlet of the hot air gun body is in communication with the hollow microneedle through the adapter. When batch-preparing 3D printing products, the lodging directions of each 3D printing product are different, and by connecting the hollow microneedle in front of the hot air gun body of the hot air gun, the blowing range of the hot air gun is reduced, and more accurate blowing and shaping can be performed on each 3D printing product or even the lodging part thereof.

[0013] In some possible implementations, when the interval between the fixing and the drying is greater than 30 min, the liquid environment in which the 3D printing product is located is replaced with deionized water after the fixing. In some possible implementations, the specific operation is as follows: a container containing the 3D printing product and the substrate is taken out together with the liquid therein and soaked in deionized water, then taken out again and soaked in new deionized water, and the above operation is repeated until the concentration of the fixing solution in the container is less than 0.0001 (v / v) %.

[0014] When the 3D printing product is soaked in the fixing solution for too long, the structure of the 3D printing product may be shed due to a reaction with the fixing solution. The inventors of the present application have found that the 3D printing product can be stably stored in deionized water after fixing, and therefore, when the drying is not performed within a short time after the fixing, the structure failure of the 3D printing product can be further avoided by replacing the fixing solution with deionized water. In other possible implementations, if the 3D printing product is directly dried within 30 min after the fixing, the influence of the soaking on the 3D printing product can be ignored, and therefore, the step can be skipped.

[0015] In some possible implementations, the drying is critical point drying, and before the 3D printing product is subjected to the critical point drying, the liquid environment in which the 3D printing product is located is replaced with a critical point drying reagent. In some possible implementations, the specific operation is as follows: a container containing the 3D printing product and the substrate is taken out together with the liquid therein and soaked in a critical point drying solvent, then taken out again and soaked in a new critical point drying solvent, and the above operation is repeated until the concentration of the critical point drying solvent in the container is greater than 97 (v / v) %.

[0016] In some possible implementations, the critical point drying reagent is ethanol. In other possible implementations, other critical point drying solvents commonly used in the art or other low surface tension drying methods can also be used by those skilled in the art.

[0017] In some possible implementations, step (1) comprises the following steps:

[0018] (a) placing the 3D printed product and the substrate in a first container, and then adding a developing solution to the first container, wherein the depth of the first container is greater than the total height of the 3D printed product and the substrate, and the developing solution in the first container covers the 3D printed product and the substrate;

[0019] (b) moving the first container into a second container and adding a developing solution to the second container until the first container is covered, so that the 3D printed product is developed, wherein the depth of the second container is greater than the depth of the first container;

[0020] (c) removing the first container from the second container, then removing the developing solution in the second container and adding a fixing solution to the second container, and finally moving the first container into the second container so that the 3D printed product is fixed;

[0021] The fixing solution in the second container covers the first container, and the amount of the fixing solution added is sufficient to fully react with the developing solution in the first container and fix the 3D printed product.

[0022] In the above technical solution, the cooperation of the first container and the second container ensures that the 3D printed product and the substrate are always immersed in a liquid environment during the replacement of the liquid reagent, thereby avoiding the structural failure of the 3D printed product caused by the surface tension of the liquid during the traditional direct solution replacement.

[0023] In the above technical solution, the material and size of the first container and the second container can be selected by those skilled in the art according to actual use requirements, as long as the 3D printed product and the substrate can be placed flat in the first container, the first container can be placed flat in the second container, the second container can hold enough developing solution and fixing solution for the 3D printed product to be fully developed and fixed, and the first container and the second container do not react with the reagents used in the post-processing process.

[0024] In some possible implementations, step (c) further comprises: when the liquid level of the developing solution in the first container is higher than the total height of the 3D printed product and the substrate, removing part of the developing solution so that the developing solution just covers the 3D printed product and the substrate. In the above technical solution, by removing part of the developing solution, the amount of the fixing solution required in the subsequent process is reduced.

[0025] A 3D printing product is printed by two-photon polymerization additive manufacturing and post-processed by the above-mentioned post-processing process.

[0026] The present application has at least the following beneficial effects: the 3D printing product is always in a liquid environment before drying, and then the 3D printing product is dried by a drying method with low surface tension, which reduces the bending or lodging degree of the 3D printing product caused by the surface tension of the liquid during the replacement of the solution in development and fixing and the volatilization of the solution in the drying process, and avoids the situation that the top of the 3D printing product is attached to the bottom. Generally speaking, after the above two steps, the large aspect ratio structure of the 3D printing product will still have a certain degree of lodging, therefore, the present technical solution blows the 3D printing product in the opposite direction of lodging by using a hot air gun, so as to restore the lodging part of the 3D printing product to an upright state. The steps of the above-mentioned post-processing process work together to ensure that the 3D printing product with a large aspect ratio will not have a structural failure problem in the post-processing process. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 A schematic diagram of the three-dimensional structure of the 3D printing product with a large aspect ratio based on two-photon polymerization additive manufacturing printing in Example 1;

[0028] Figure 2 A front view of the 3D printing product in Example 1;

[0029] Figure 3 A right view of the 3D printing product in Example 1;

[0030] Figure 4 A top view of the 3D printing product in Example 1;

[0031] Figure 5 A flowchart of the development, fixing and storage of the 3D printing product in Example 1 in a full liquid environment;

[0032] Figure 6 A microscopic photograph of the 3D printing product in Example 1 after critical point drying;

[0033] Figure 7 A schematic diagram of blowing the 3D printing product by using a hot air gun in Example 1;

[0034] Figure 8 An electron microscope photograph of the microstructure of the 3D printing product in Example 1 blown straight by using a hot air gun;

[0035] Figure 9 A schematic diagram of the structure of the hot air gun used in Example 1;

[0036] Figure 10 A schematic diagram of the structure of the adapter of the hot air gun in Example 1;

[0037] Figure 11 Micrograph of the 3D printed product after critical point drying in Example 2;

[0038] Figure 12 Schematic diagram of the 3D printed product being blown with a heat gun in Example 2;

[0039] Figure 13 Schematic diagram of the 3D printed product being blown with a heat gun in Example 2;

[0040] Figure 14 SEM image of the comparative printed product after drying made in Comparative Example 1.

[0041] Reference numerals in the figure: 1 - top microstructure, 2 - large aspect ratio thin plate, 3 - base, 4 - center of mass, 5 - heat gun body, 6 - 3D printed product, 7 - substrate, 8 - adapter, 9 - hollow microneedle, 10 - first port, 11 - second port. DETAILED DESCRIPTION

[0042] The technical solutions of the present application are further described and explained below through specific embodiments.

[0043] The technical solutions of the present application are described clearly and completely below in combination with the drawings of the present application; obviously, the described embodiments are only one implementation of the present application, and all other embodiments obtained by those skilled in the art without making creative efforts based on the following embodiments are within the protection scope of the present application.

[0044] In the present application, the terms "upper", "lower", "bottom", "rear", "side" and the like are indicative of the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of simplifying the description, and do not indicate or imply that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0045] In the present application, "putting / placing" or "taking out" the first container / dish refers to the operation of the first container together with the 3D printed product, substrate and liquid placed therein. The selection of the first container and the second container is not limited, as long as it has good chemical stability and does not react with the subsequent chemical reagents (developer, fixer, deionized water and critical point drying reagent). Exemplarily, in the following examples and comparative examples, a glass dish is used as the first container and a beaker is used as the second container.

[0046] The "replacement" of the present application refers to gradually replacing the solvent in the liquid environment, in which process, the 3D printing product and the substrate are always immersed in the liquid environment, so as to place the top of the 3D printing product in contact with the substrate.

[0047] Example 1

[0048] Example 1 uses two-photon polymerization additive manufacturing to print a 3D printing product with a large aspect ratio, and the structure is as shown in Figures 1-4 The 3D printing product from top to bottom includes a top microstructure 1, a large aspect ratio thin plate 2 and a base 3. The top microstructure 1 is an arc top structure with a cavity in the middle; the size of the large aspect ratio thin plate 2 is 0.5 μm x 4 μm x 120 μm; the base 3 is a cuboid with a length of 50 μm, a width of 50 μm and a height of 20 μm; in the vertical direction, the center of mass 4 of the 3D printing product is in the plane of the large aspect ratio thin plate 2.

[0049] After the printing is completed, the 3D printing product is post-processed by using the post-processing process provided by the present application, which specifically includes the following steps:

[0050] (1) Take a small glass culture dish, place the 3D printing product and the substrate in the culture dish, then add the developing solution to the glass culture dish until it completely covers the 3D printing product and the substrate, the depth of the culture dish is greater than the total height of the 3D printing product and the substrate, and the 3D printing product and the substrate are placed flat in the culture dish.

[0051] (2) Soak the above culture dish and the 3D printing product and substrate in it into a beaker containing developing solution, the developing solution in the beaker is in communication with the developing solution in the culture dish, and the 3D printing product is developed until the developing solution in the beaker is in communication with the developing solution in the culture dish. The depth of the beaker is greater than the depth of the culture dish, the culture dish is placed flat in the beaker, and the beaker contains excess developing solution.

[0052] (3) Take out the culture dish, 3D printing product and substrate, since the culture dish and the beaker are in liquid communication in step (2), at this time the culture dish contains a large amount of developing solution, remove part of the developing solution with a dropper until the liquid level of the developing solution is roughly level with the highest point of the 3D printing product.

[0053] (4) Replace the developing solution in the beaker with a fixing solution, then place the culture dish, 3D printing product and substrate again in the beaker, at this time the fixing solution in the beaker can cover the culture dish, the beaker contains excess fixing solution, which is sufficient to consume the residual developing solution in the culture dish and make the 3D printing product fully fixed.

[0054] This embodiment dries the 3D printing product after fixing for 1 hour, therefore, in order to prevent the fixing solution from reacting with the 3D printing product and causing the 3D printing product to fall off, etc., the fixing solution needs to be replaced with deionized water. The specific operation is as follows:

[0055] (5) Take the Petri dish, 3D printing product and substrate out of the beaker, add deionized water into the beaker, then lay the Petri dish, 3D printing product and substrate in the beaker, then take them out, replace the liquid in the beaker with new deionized water, repeat the above operation 6 times, at this time the concentration of fixer in the Petri dish is less than 0.0001% (v / v) %.

[0056] The drying method of this embodiment is critical point drying, in which liquid CO2 is used as the liquid environment and the drying is achieved by converting liquid CO2 into gas. Since water and liquid CO2 are not miscible, it is necessary to replace deionized water with a reagent that can be miscible with liquid CO2, such as ethanol and acetone. In this embodiment, deionized water is replaced with ethanol, and the specific operation is as follows:

[0057] (6) Take the Petri dish, 3D printing product and substrate out of the container containing deionized water, add ethanol into the beaker, then lay the Petri dish, 3D printing product and substrate in the beaker, then take them out, replace the liquid in the beaker with new ethanol, repeat the above operation 2 times, at this time the concentration of ethanol in the Petri dish is greater than 97% (v / v) %.

[0058] In this embodiment, the replacement of deionized water and ethanol is achieved by a beaker, and in other possible implementations, other containers can be used. The number of repetitions in steps (5) and (6) can be determined by the volume ratio of the Petri dish to the container containing ethanol / deionized water, or the concentration of the solution in the Petri dish can be directly measured.

[0059] (7) Use a critical point dryer to dry the 3D printing product, and place the substrate and 3D printing product into the critical point dryer.

[0060] In other possible implementations, the critical point drying used in step (6) can be replaced by other drying methods known to those skilled in the art with lower surface tension, as long as the sample does not collapse, stick to the bottom, etc. after drying.

[0061] After step (7) drying, the obtained 3D printing product is as shown in Figure 6 From the figure, it can be seen that after development, fixing and drying, the large aspect ratio sheet 2 of the 3D printing product is bent, but the top microstructure 1 does not contact the base 3.

[0062] In order to reduce the bending degree of the large aspect ratio sheet 2 and make it closer to the structure shown in Figures 1-4 , it is necessary to use a heat gun to blow the 3D printing product, and the specific operation is as follows:

[0063] (8) Refer to Figure 7After critical point drying, the substrate 7 is fixed under a microscope for observation. At the same time, a hot air gun is used to blow the 3D printed product 6 from the side against the tilting direction of the high aspect ratio thin plate 2, and the air flow intensity is gradually increased until the sample tilts slightly in the other direction. Keep it for a few seconds, then stop blowing and observe under the microscope. If it does not return to the upright effect, continue blowing until the structure is in an upright state when the hot air gun stops blowing. The final 3D printed product is as follows Figure 8 As shown, it can be seen that the 3D printed product is basically in an upright state.

[0064] Among them, the specific structure of the hot air gun is as follows Figure 9 and Figure 10 As shown, it includes a hot air gun body 5, an adapter 8 and a hollow microneedle 9. The adapter 8 has a first port 10 and a second port 11 that are connected. The shape of the first port 10 is adapted to the air outlet of the hot air gun body 5, and the shape of the second port 11 is adapted to the hollow microneedle 9. The hot air gun body 5 and the hollow microneedle 9 are plugged into the adapter 8 through the first port 10 and the second port 11 respectively and fixed by epoxy resin glue. Through the above arrangement, the air outlet of the hot air gun body 5 is connected to the hollow microneedle 9, and hot air is blown out from the hollow microneedle 9. This design reduces the blowing range of the hot air blower, enabling it to Figure 6 The 3D printed products shown have different lodging directions and are selectively blown.

[0065] Example 2

[0066] The difference between Example 2 and Example 1 is that Figure 11 As shown, the 3D printed products have the same lodging direction, so in this embodiment, the hot air gun only has a hot air gun body 5 ( Figure 12 and Figure 13 ), the air outlet of the hot air gun body 5 directly discharges air and blows multiple 3D printed products together.

[0067] Comparative Example 1

[0068] The difference between Comparative Example 1 and Example 1 is that in steps (1) to (4), the comparative print product and the substrate are directly placed in or taken out of the beaker. During this process, due to multiple separations from the liquid environment, the surface tension of each liquid causes the comparative print product to deform. Since the comparative document 1 is then air-dried, only step (5) is performed to replace the fixing solution with deionized water to reduce the contact time between the comparative print product and the fixing solution. There is no need to perform steps (6) and (7). After air-drying, the comparative print product is obtained, and its morphology is as follows: Figure 14 As shown, it can be seen that the thin plate 2 with a large aspect ratio in the comparison printed product has been twisted and stuck to the bottom.

[0069] Afterwards, the applicant tried to reshape the dried comparative print product using the method shown in step (8) of Example 1, but the top microstructure 1 of the comparative print product could not be restored to an upright state under the blowing of hot air because it was adhered to the base.

[0070] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used in the description herein is for describing particular embodiments only and is not intended to be limiting of the application. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items.

[0071] Any combination of the technical features of the above embodiments can be made, and in order to make the description simple, each technical feature in the above embodiments is not described in all possible combinations, however, as long as the combination of the technical features does not exist, it should be considered as the scope of the description.

[0072] The above embodiments only express several implementation manners of the present application, and the description is more specific and detailed, but it should not be understood as a limitation on the scope of the patent. It should be pointed out that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the protection scope of the present application. Therefore, the protection scope of the patent of the present application should be subject to the appended claims.

Claims

1. A post-processing process for two-photon polymerization additive manufacturing, wherein the two-photon polymerization additive manufacturing prints on a substrate to obtain a 3D printed product, wherein the 3D printed product has a high aspect ratio structure, characterized in that: The post-processing process comprises the following steps: (1) Immersing the 3D printed product and the substrate in a developer, replacing the developer with a fixer after the 3D printed product is completely developed, and allowing the 3D printed product to stand for fixation; Wherein, in the step (1), the 3D printed product and the substrate are always immersed in a liquid environment; (2) drying the 3D printed product and the substrate using a low surface tension drying method; (3) Using a hot air gun, blow the 3D printed product until the 3D printed product stands upright, wherein the blowing direction is opposite to the falling direction of the 3D printed product.

2. The post-processing process according to claim 1, wherein: The hot air gun comprises a hot air gun body, an adapter and hollow microneedles, and the air outlet of the hot air gun body is connected to the hollow microneedles through the adapter.

3. The post-processing process according to claim 1, wherein: When the interval between the fixing and the drying is greater than 30 minutes, the method further includes replacing the liquid environment of the 3D printed product with deionized water after the fixing.

4. The post-processing process according to any one of claims 1 to 3, characterized in that: The drying is critical point drying. Before the critical point drying is performed on the 3D printed product, the liquid environment in which the 3D printed product is located is replaced with a critical point drying agent.

5. The post-processing process according to claim 4, characterized in that: The critical point drying agent is ethanol.

6. The post-processing process according to claim 1, wherein: The step (1) comprises the following steps: (a) placing the 3D printed product and the substrate in a first container containing a developer, and then adding the developer to the first container, wherein the depth of the first container is greater than the total height of the 3D printed product and the substrate, and the developer in the first container covers the 3D printed product and the substrate; (b) moving the first container into a second container and adding developer solution into the second container until the developer solution covers the first container to develop the 3D printed product, wherein the depth of the second container is greater than the depth of the first container, and the developer solution in the first container and the second container is sufficient to develop the 3D printed product; (c) removing the first container from the second container, removing the developer in the second container, adding a fixer into the second container, and finally moving the first container into the second container to fix the 3D printed product; The fixing solution in the second container covers the first container, and the amount of the fixing solution added is sufficient to fully react with the developing solution in the first container and fix the 3D printed product.

7. The post-processing process according to claim 6, characterized in that: The step (c) further includes: when the liquid level of the developer in the first container is higher than the total height of the 3D printed product and the substrate, removing part of the developer so that the developer just covers the 3D printed product and the substrate.

8. A 3D printed product, characterized in that: The material is obtained by two-photon polymerization additive manufacturing printing and post-processing using the post-processing process described in any one of claims 1 to 7.

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