Modified PLA material for 3D printing and preparation method thereof

Abstract

The application discloses a modified PLA material for 3D printing and a preparation method thereof, wherein raw materials of the modified PLA material comprise a PLA resin, a three-arm cage-shaped PLA oligomer, a flow aid, and a toughening agent. The modified PLA material is prepared by firstly preparing the three-arm cage-shaped PLA oligomer by self-making and then melt-extruding the three-arm cage-shaped PLA oligomer and the PLA resin. The three-arm cage-shaped PLA oligomer is introduced, the molecular weight distribution width of the material is increased, the flowability of the material is improved, the PLA material can be applied to high-speed FDM printing, the interlayer molecular chain winding is strengthened during the printing melt deposition process, the interlayer combination is greatly improved, the aid on the surface of the material is reduced during the printing process, and the interlayer combination during printing is synergistically strengthened.

Description

Technical Field

[0001] This invention belongs to the field of 3D printing materials, and particularly relates to a high-strength interlayer bond modified PLA material suitable for high-speed 3D printing and its preparation method. Background Technology

[0002] 3D printing, especially material extrusion fused deposition modeling (FDM), offers advantages such as ease of operation and low cost, leading to its widespread application in industries such as crafts, medical protective gear, and custom parts. PLA materials, with their advantages of low printing cost and excellent forming results, have also found widespread use in the 3D printing field.

[0003] Conventional FDM printing typically operates at speeds of 30-60 mm / s, resulting in low printing efficiency and limiting its application in production. In recent years, breakthroughs in FDM technology have led to the emergence of more and more high-speed FDM printers on the market, achieving speeds of 300-600 mm / s, largely addressing the issue of low printing efficiency. However, with these technological advancements, conventional PLA printing materials are prone to problems such as weak interlayer bonding, poor appearance, and poor extrusion when printed at high speeds.

[0004] Patent CN110317442A discloses a high-bonding-strength, light-shielding 3D printing PLA material, its preparation method, and its applications. By adding a low-viscosity compound modifier containing epoxy groups, a flow modifier, and a melt conditioner to adjust melt flowability, it is beneficial to improve the printed appearance. Increasing the viscosity of the material during melting enhances interlayer bonding. Material viscosity is significantly affected by temperature. At conventional printing speeds, the melt temperature is relatively stable, but under high-speed printing conditions, if the material viscosity remains high, it will cause continuous overflow at the edges of the printed part, severely affecting the printed appearance and even preventing printing altogether.

[0005] Patent CN116376245A discloses an FDM 3D printer consumable and its preparation method that enables fast printing and shortens the cycle time. It improves the flowability of PLA material by adding a large amount of powder, so that the material can be used for high-speed printing. However, the addition of a large amount of powder can easily migrate to the material surface or even precipitate during the printing process, which will cause a serious decrease in the interlayer bonding of the printed parts.

[0006] Therefore, it is essential to develop a modified PLA material and its preparation method that can simultaneously achieve high-speed printing and high-strength interlayer bonding. Summary of the Invention

[0007] The purpose of this invention is to provide a modified PLA material for 3D printing and its preparation method. The introduction of a self-made three-armed cage-like PLA oligomer has the following main advantages: First, it reduces the overall molecular weight of the material, increases the molecular weight distribution width, and improves the material's fluidity, making the PLA material suitable for high-speed FDM printing; Second, the three-armed oligomer with the same structure as the matrix resin easily migrates to the melt surface during high-speed printing, strengthening the interlayer molecular chain entanglement during the molten deposition process and significantly improving interlayer bonding; Third, due to its cage-like structure, it can adsorb powdered additives in the material, reducing additive precipitation on the material surface during printing and synergistically strengthening the interlayer bonding during printing.

[0008] To achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0009] A modified PLA material for 3D printing, the modified PLA material comprising the following components by weight percentage:

[0010] S1, PLA resin, 75%-95%, preferably 83%-90%;

[0011] S2, three-armed cage-like PLA oligomers, 1%-20%, preferably 8%-15%;

[0012] S3, flow aid, 1.0-5.0%, preferably 1%-2%;

[0013] S4, toughening agent, 0.1%-0.5%, preferably 0.2%-0.4%.

[0014] The PLA resin described in this invention has a melt index of 1-15 / 10min (190℃, 2.16kg) and a molecular weight of 50,000-150,000 g / mol.

[0015] The flow aid described in this invention is one or more of oleamide, ethylene bis-stearamide, zinc stearate, wollastonite powder, and talc powder, preferably one or more of zinc stearate and wollastonite powder.

[0016] The toughening agent of the present invention is preferably one or more of YF6030, YP-501, AX8900, Wacker2504, and Wacker2505.

[0017] The three-armed cage-like PLA oligomer (T-LMW) of this invention is an oligomer generated by the reaction of trisilyl alcohol polysilsesquioxane and lactide under the action of a catalyst; preferably, the trisilyl alcohol polysilsesquioxane is one or more of trisilyl alcohol phenyl polysilsesquioxane, trisilyl alcohol octyl polysilsesquioxane, and trisilyl alcohol isooctyl polysilsesquioxane, and more preferably one or more of trisilyl alcohol octyl polysilsesquioxane and trisilyl alcohol isooctyl polysilsesquioxane;

[0018] Preferably, the lactide is one or more of L-lactide, D-lactide, and DL-lactide, and more preferably DL-lactide.

[0019] Preferably, the catalyst is an organotin catalyst, preferably one or more of stannous octoate, stannous hexanoate, and stannous pyrophosphate, and more preferably stannous octoate.

[0020] Preferably, the molar ratio of the catalyst to trisilyl alcohol polysilsesquioxane is 1:10-1:30, more preferably 1:15-1:20.

[0021] Preferably, the molar ratio of the trisilyl alcohol polysilsesquioxane to lactide is 1:100-1:400, more preferably 1:200-1:250.

[0022] Preferably, the reaction temperature of the trisilyl alcohol polysilsesquioxane with lactide is 80-120°C.

[0023] In one embodiment, the method for preparing the three-armed cage-like PLA oligomer includes the following steps: adding trisilyl alcohol polysilsesquioxane and lactide to a solvent (such as toluene), mixing thoroughly, heating at 80-120°C, preferably at 90-105°C, until completely dissolved, adding a catalyst, and maintaining the temperature for 4-6 hours; after the reaction is complete, transferring to an ice bath, separating and drying to obtain the three-armed cage-like PLA oligomer.

[0024] Preferably, the reaction solution obtained from the reaction is completely dissolved in dichloromethane, then poured into methanol, centrifuged and filtered to obtain a precipitate, which is then dried to obtain a three-armed cage-like PLA oligomer.

[0025] Another object of the present invention is to provide a method for preparing modified PLA material for 3D printing.

[0026] A method for preparing modified PLA material for 3D printing includes the following steps: mixing PLA, three-armed cage-like PLA oligomer, flow aid, and toughening agent, then adding the mixture to a twin-screw extruder for melt extrusion, cooling, pelletizing, and drying to obtain modified PLA particles;

[0027] Preferably, the modified PLA particles are added to a single-screw extruder for melt extrusion and then cooled to obtain the modified PLA material.

[0028] Preferably, in the preparation method of the modified PLA material, a high-speed mixer is used for mixing at a speed of 20-100 rpm, a temperature of 20-50℃, and a mixing time of 3-10 min; the screw temperature of the twin-screw extruder is 160-190℃, and the speed is 200-400 rpm; the screw temperature of the single-screw extruder is 180-200℃, and the speed is 100-200 rpm.

[0029] Compared with the prior art, the present invention has the following technical advantages:

[0030] 1) This application introduces a self-made three-armed cage-like PLA oligomer to reduce the overall molecular weight of the material, increase the molecular weight distribution width of the material, and improve the fluidity of the material, so that the PLA material can be used for high-speed FDM printing, which can solve appearance problems such as missing material and poor material output during high-speed printing.

[0031] 2) This application introduces a self-made three-armed cage-like PLA oligomer with the same overall molecular structure as the matrix, so there is no compatibility problem. Moreover, due to its low molecular weight, it is easy to migrate to the surface of the melt during high-speed printing. During the printing molten deposition process, it will strengthen the interlayer molecular chain entanglement and greatly improve the interlayer bonding, which can solve the problem of weak interlayer bonding during high-speed printing.

[0032] 3) This application introduces a self-made three-armed cage-like PLA oligomer. Due to its cage-like structure, it can adsorb powder additives in the material, ensuring smooth printing while reducing the precipitation of additives on the material surface during printing, and synergistically strengthening the interlayer bonding of the print. Detailed Implementation

[0033] The present invention will be further illustrated below with specific embodiments. These embodiments are merely illustrative and do not limit the scope of the invention.

[0034] The main sources of raw materials in each embodiment and comparative example are shown in Table 1 below:

[0035] Table 1 Raw Materials and Sources

[0036] PLA(LX575) Total Klein Polylactic Acid Co., Ltd. PLA(LX175) Total Klein Polylactic Acid Co., Ltd. Zinc stearate as a flow aid Shandong Siyang Biotechnology Co., Ltd. Toughening agent Wacker 2504 Shanghai Kaiyin Chemical Co., Ltd. Trisilyl octyl polysilsesquioxane Xi'an Qiyue Biotechnology Co., Ltd. Trisilyl isooctyl polysilsesquioxane Xi'an Qiyue Biotechnology Co., Ltd. Trimethylolbutane Sigma Aldrich (Shanghai) Trading Co., Ltd. DL-lactide Total Klein Polylactic Acid Co., Ltd. dichloromethane Shanghai Aladdin Biochemical Technology Co., Ltd. methanol Shanghai Aladdin Biochemical Technology Co., Ltd. Stannous octoate Sigma Aldrich (Shanghai) Trading Co., Ltd.

[0037] Unless otherwise specified, all other raw materials and reagents were obtained through commercially available channels.

[0038] The performance test parameters and test methods of the modified PLA materials in each embodiment and comparative example are shown in Table 2 below:

[0039] Table 2 Performance Test Parameters and Methods

[0040] Melt Flow Index g / 10min ISO 1133 Tensile strength MPa ISO 527-2 Appearance evaluation / Visual inspection

[0041] The processing equipment used is: a twin-screw extruder, Coperon, model ZSK 26Mc 18, with a length-to-diameter ratio of 52 and a screw diameter of 26cm; and a single-screw extruder, Herejia, model HRJSJ-Ф45, with a screw diameter of 45mm and a die diameter of 1.75mm.

[0042] The testing equipment used was: a Gottfert melt flow indexer from Germany, with melt flow index test conditions of 190℃ and 2.16kg; and a ZWICK universal testing machine from Germany, with tensile test conditions of 50mm / min.

[0043] Example 1

[0044] (1) Preparation of three-armed cage-like PLA oligomer (T-LMW-1)

[0045] Weigh 144g of DL-lactide and 6g of trisilyl polysilsesquioxane (the molar ratio of trisilyl polysilsesquioxane to lactide is 1:200) and add them to a round-bottom flask. Add 100mL of toluene, stir continuously, and heat to 90℃ until completely dissolved. Then add 5g of stannous octoate and keep the temperature constant for 4h. After the reaction is complete, transfer to an ice bath, add 200mL of dichloromethane to completely dissolve the product, pour in a large amount of pre-cooled methanol, centrifuge and filter to obtain the precipitate, and dry it under vacuum at 40℃ to obtain a three-armed cage-like PLA oligomer.

[0046] (2) Modified PLA materials were prepared using the three-armed cage-like PLA oligomer (T-LMW-1) of this embodiment, according to the following method. The mass amounts of each component are shown in Table 3. First, the PLA resin and the three-armed cage-like PLA oligomer (T-LMW-1) were dried in an electric heating drying oven at 80°C for 4 hours. Then, the PLA resin, the three-armed cage-like PLA oligomer (T-LMW-1), the flow aid, and the toughening agent were placed in a high-speed mixer with a speed of 50 rpm and a temperature of 35°C for 5 minutes. The sample was then melt-extruded in a twin-screw extruder. The screw temperature was set to 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 185°C, 190°C, and 190°C in sections from the feed port to the die head, and the screw speed was set to 300 rpm. The extruded material is cooled and pelletized in an extruder water tank, then dried in an oven at 80°C for 4 hours to obtain the modified PLA particles. The modified PLA particles are then added to a single-screw extruder for melt extrusion and cooling. The screw temperature is set in sections from the feed port to the die at 180°C, 180°C, 185°C, 185°C, 190°C, 190°C, 190°C, and 200°C, and the screw speed is set to 150 rpm to produce the modified PLA material.

[0047] Example 2

[0048] (1) Preparation of three-armed cage-like PLA oligomer (T-LMW-2)

[0049] Weigh 144g of DL-lactide and 4.8g of trisilyl octyl polysilsesquioxane (the molar ratio of trisilyl octyl polysilsesquioxane to lactide is 1:250) and add them to a round-bottom flask. Add 100mL of toluene, stir continuously, and heat to 90℃ until completely dissolved. Then add 5g of stannous octoate and keep the temperature constant for 4h. After the reaction is complete, transfer to an ice bath, add 200mL of dichloromethane to completely dissolve the product, pour in a large amount of pre-cooled methanol, centrifuge and filter to obtain the precipitate, and dry it under vacuum at 40℃ to obtain a three-armed cage-like PLA oligomer.

[0050] (2) Modified PLA materials were prepared using the three-armed cage-like PLA oligomer (T-LMW-2) of this embodiment, according to the following method. The mass amounts of each component are shown in Table 3. First, the PLA resin and the three-armed cage-like PLA oligomer (T-LMW-2) were dried in an electric heating drying oven at 80°C for 4 hours. Then, the PLA resin, the three-armed cage-like PLA oligomer (T-LMW-2), the flow aid, and the toughening agent were placed in a high-speed mixer with a speed of 50 rpm and a temperature of 35°C for 5 minutes. The sample was then melt-extruded in a twin-screw extruder. The screw temperature was set to 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 185°C, 190°C, and 190°C in sections from the feed port to the die head, and the screw speed was set to 300 rpm. The extruded material is cooled and pelletized in an extruder water tank, then dried in an oven at 80°C for 4 hours to obtain the modified PLA particles. The modified PLA particles are then added to a single-screw extruder for melt extrusion and cooling. The screw temperature is set in sections from the feed port to the die at 180°C, 180°C, 185°C, 185°C, 190°C, 190°C, 190°C, and 200°C, and the screw speed is set to 150 rpm to produce the modified PLA material.

[0051] Example 3

[0052] (1) Preparation of three-armed cage-like PLA oligomer (T-LMW-3)

[0053] Weigh 144g of DL-lactide and 4.0g of trisilyl phenyl polysilsesquioxane (the molar ratio of trisilyl phenyl polysilsesquioxane to lactide is 1:300) and add them to a round-bottom flask. Add 100mL of toluene, stir continuously, and heat to 90℃ until completely dissolved. Then add 5g of stannous octoate and keep the temperature constant for 4h. After the reaction is complete, transfer to an ice bath, add 200mL of dichloromethane to completely dissolve the product, pour in a large amount of pre-cooled methanol, centrifuge and filter to obtain the precipitate, and dry it under vacuum at 40℃ to obtain a three-armed cage-like PLA oligomer.

[0054] (2) Modified PLA materials were prepared using the three-armed cage-like PLA oligomer (T-LMW-3) of this embodiment, according to the following method. The mass amounts of each component are shown in Table 3. First, the PLA resin and the three-armed cage-like PLA oligomer (T-LMW-3) were dried in an electric heating drying oven at 80°C for 4 hours. Then, the PLA resin, the three-armed cage-like PLA oligomer (T-LMW-3), the flow aid, and the toughening agent were placed in a high-speed mixer with a speed of 50 rpm and a temperature of 35°C for 5 minutes. The sample was then melt-extruded in a twin-screw extruder. The screw temperature was set to 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 185°C, 190°C, and 190°C in sections from the feed port to the die head, and the screw speed was set to 300 rpm. The extruded material is cooled and pelletized in an extruder water tank, then dried in an oven at 80°C for 4 hours to obtain the modified PLA particles. The modified PLA particles are then added to a single-screw extruder for melt extrusion and cooling. The screw temperature is set in sections from the feed port to the die at 180°C, 180°C, 185°C, 185°C, 190°C, 190°C, 190°C, and 200°C, and the screw speed is set to 150 rpm to produce the modified PLA material.

[0055] Example 4

[0056] Three-armed cage-like PLA oligomers (T-LMW-3) and modified PLA materials were prepared using the same method as in Example 3, the only difference being the amount of T-LMW-3 added to the PLA materials.

[0057] Comparative Example 1

[0058] Modified PLA materials were prepared according to the method in Example 1, with the only difference being the different formulation composition in Table 3, without the addition of three-armed cage-like PLA oligomers.

[0059] Comparative Example 2

[0060] The three-arm PLA oligomer (T-LMW-4) and modified PLA material were prepared using the same method as in Example 1, except that trisilyl octyl polysilsesquioxane was replaced with trimethylolbutane. Therefore, the three-arm PLA oligomer (T-LMW-4) did not have a cage-like structure.

[0061] Comparative Example 3

[0062] Modified PLA materials were prepared according to the method in Example 1, with the only difference being the different formulation composition in Table 3. The self-made three-armed cage-like PLA oligomer was replaced with a commercially available linear PLA oligomer (Yusi Pharmaceutical YS-PLA201)(T-LMW-5).

[0063] The modified PLA materials obtained in Examples 1-4 and Comparative Examples 1-3 were printed using a high-speed FDM printer. The nozzle temperature was set to 210°C, the substrate temperature to 60°C, and the printing speed to 300 mm / s. Tensile standard specimens in the X-axis, Y-axis, and Z-axis directions were printed. The interlayer bonding strength of the material was characterized by testing the tensile properties. The test results are shown in Table 4.

[0064] Table 3. Raw materials and amounts (mass fraction) in Examples 1-4 (A1-A4) and Comparative Examples 1-3 (B1-B3)

[0065] PLA(LX575) 90 80 70 63 98 90 90 PLA(LX175) - 10 20 20 - - - Zinc stearate 1.8 1.7 1.6 1.6 1.8 1.8 1.8 Wacker2504 0.2 0.3 0.4 0.4 0.2 0.2 0.2 T-LMW-1 8 - - - - - - T-LMW-2 - 8 - - - - - T-LMW-3 - - 8 15 - - - T-LMW-4 - - - - - 8 - T-LMW-5 - - - - - - 8

[0066] Table 4. Performance test results of samples from Examples 1-4 (A1-A4) and Comparative Examples 1-3 (B1-B3)

[0067]

[0068] As can be seen from Comparative Examples 1-4 and Example 1, compared with traditional 3D printing materials (Comparative Example 1) or conventional flowability-optimized 3D printing materials (Comparative Example 3), this invention introduces a self-made three-armed cage-like PLA oligomer. First, it reduces the overall molecular weight of the material, increases the molecular weight distribution width, and improves the flowability of the material, making the PLA material suitable for high-speed FDM printing, resulting in significantly better appearance of the high-speed printed products. Second, the three-armed oligomer with the same structure as the matrix resin easily migrates to the melt surface during high-speed printing, strengthening the interlayer molecular chain entanglement during the printing melt deposition process, greatly improving interlayer bonding, and significantly increasing the Z-axis tensile strength. Third, due to its cage-like structure, it can adsorb powder additives in the material, reducing the precipitation of additives on the material surface during printing, synergistically strengthening the interlayer bonding and improving the appearance of the printed parts.

[0069] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A modified PLA material for 3D printing, characterized in that, The modified PLA material comprises the following components by weight percentage: S1, PLA resin, 75%-95%; S2, three-armed cage-like PLA oligomers, 1%-20%; S3, flow aid, 1.0-5.0%; S4, toughening agent, 0.1%-0.5%; The three-armed cage-like PLA oligomer is an oligomer generated by the reaction of trisilyl alcohol polysilsesquioxane and lactide under the action of a catalyst; The trisilyl alcohol polysilsesquioxane is one or more of trisilyl alcohol phenyl polysilsesquioxane, trisilyl alcohol octyl polysilsesquioxane, and trisilyl alcohol isooctyl polysilsesquioxane.

2. The modified PLA material according to claim 1, characterized in that, The modified PLA material comprises the following components by weight percentage: S1, PLA resin, 83%-90%; S2, three-armed cage-like PLA oligomers, 8%-15%; S3, flow aid, 1%-2%; S4, toughening agent, 0.2%-0.4%.

3. The modified PLA material according to claim 1, characterized in that, The PLA resin has a melt index of 1-15 / 10min at 190℃ and a molecular weight of 50,000-150,000 g / mol at 2.16 kg.

4. The modified PLA material according to claim 1, characterized in that, The flow aid is one or more of oleamide, ethylene bis-stearamide, zinc stearate, wollastonite powder, and talc powder.

5. The modified PLA material according to claim 4, characterized in that, The flow aid is one or more of zinc stearate and wollastonite powder.

6. The modified PLA material according to claim 1, characterized in that, The toughening agent is one or more of YF6030, YP-501, AX8900, Wacker2504, and Wacker2505.

7. The modified PLA material according to claim 1, characterized in that, The trisilyl polysilsesquioxane is one or more of trisilyl octyl polysilsesquioxane and trisilyl isooctyl polysilsesquioxane.

8. The modified PLA material according to claim 1, characterized in that, The lactide is selected from one or more of L-lactide, D-lactide, and DL-lactide.

9. The modified PLA material according to claim 8, characterized in that, The lactide is selected from DL-lactide.

10. The modified PLA material according to claim 1, characterized in that, The catalyst is an organotin catalyst.

11. The modified PLA material according to claim 10, characterized in that, The catalyst is one or more of stannous octoate, stannous hexanoate, and stannous pyrophosphate.

12. The modified PLA material according to claim 11, characterized in that, The catalyst is stannous octoate.

13. The modified PLA material according to claim 1, characterized in that, The molar ratio of the catalyst to trisilyl alcohol polysilsesquioxane is 1:10 to 1:

30.

14. The modified PLA material according to claim 13, characterized in that, The molar ratio of the catalyst to trisilyl alcohol polysilsesquioxane is 1:15-1:

20.

15. The modified PLA material according to claim 1, characterized in that, The molar ratio of the trisilyl alcohol polysilsesquioxane to lactide is 1:100-1:

400.

16. The modified PLA material according to claim 15, characterized in that, The molar ratio of the trisilyl alcohol polysilsesquioxane to lactide is 1:200-1:

250.

17. The modified PLA material according to claim 1, characterized in that, The reaction temperature of the trisilyl alcohol polysilsesquioxane with lactide is 80-120℃.

18. The modified PLA material according to claim 1, characterized in that, The preparation method of the three-armed cage-like PLA oligomer includes the following steps: adding trisilyl alcohol polysilsesquioxane and lactide to a solvent, mixing thoroughly, heating at 80-120℃ until completely dissolved, adding a catalyst, and maintaining the temperature for 4-6 hours; after the reaction is completed, transferring to an ice bath, separating and drying to obtain the three-armed cage-like PLA oligomer.

19. The modified PLA material according to claim 18, characterized in that, After adding trisilyl alcohol polysilsesquioxane and lactide, heat at 90-105℃.

20. A method for preparing a modified PLA material for 3D printing according to any one of claims 1-19, comprising the following steps: mixing PLA, a three-armed cage-like PLA oligomer, a flow aid, and a toughening agent, then adding the mixture to a twin-screw extruder for melt extrusion, cooling, pelletizing, and drying to obtain modified PLA particles.

21. The preparation method according to claim 20, characterized in that, The modified PLA particles are added to a single-screw extruder for melt extrusion and then cooled to obtain the modified PLA material.

22. The preparation method according to claim 20, characterized in that, The raw materials are mixed using a high-speed mixer at a speed of 20–100 rpm, a temperature of 20–50°C, and a mixing time of 3–10 min.

23. The preparation method according to claim 21, characterized in that, The screw temperature of a twin-screw extruder is 160-190℃, and the speed is 200-400rpm; the screw temperature of a single-screw extruder is 180-200℃, and the speed is 100-200rpm.

Images