Preparation method of PUA resin material with photothermal dual-curing characteristics for 3D printing
By introducing dynamic hindered urea bonds into the polyurethane structure and employing a dual photothermal curing method, the problems of poor mechanical properties and stability of photocurable 3D printing materials were solved, and high-strength PUA resin materials were prepared, which are suitable for DLP-3D printing.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- XIAN UNIV OF TECH
- Filing Date
- 2026-03-13
- Publication Date
- 2026-06-30
AI Technical Summary
Existing photopolymer 3D printing materials suffer from poor mechanical properties, insufficient stability, and difficulty in achieving photothermal dual curing characteristics, resulting in defects in printed parts and difficulty in improving mechanical properties.
By introducing dynamically hindered urea bonds into the polyurethane structure and combining ultraviolet light and thermal curing methods, a PUA resin material with photothermal dual curing properties for 3D printing was prepared. The combination of photocuring and thermal curing was achieved by using t-BAEMA end-capping agent to form reversible urea bonds with -NCO groups.
The mechanical properties of the material were significantly improved, with a tensile strength of 1.36 MPa after 4 hours, which is 6.39 times higher than that of unmodified PUA. The material is inexpensive and readily available, making it suitable for mass production.
Smart Images
Figure CN122302206A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of 3D printing resin preparation, specifically relating to a method for preparing a PUA resin material for 3D printing with photothermal dual curing properties. Background Technology
[0002] Photopolymer 3D printing can achieve higher precision printing, but it suffers from poor performance of the printed parts. Researchers have studied various methods to improve the mechanical properties of DLP printed products, including particle reinforcement, microsphere reinforcement, and post-processing of printed products. These methods require relatively complex processing technology and high equipment performance, and can only improve the mechanical properties of printed products to a limited extent.
[0003] To address these challenges, a novel printing strategy is proposed: by introducing dynamic covalent bonds into polyurethane 3D printing materials, the interlayer bonding strength of printed products is enhanced, improving their mechanical properties. Simultaneously, the self-healing properties of these dynamic covalent bonds allow for the design of easily printable, simpler, and more independent structural components for disassembling suspended structures or large objects. These components can then be reassembled into the desired overall structure, eliminating the need for additional support structures and removing limitations imposed by printer size requirements. This ultimately achieves rapid, supportless printing. Photopolymer-printed objects are typically thermosetting, offering better overall performance than thermoplastic materials. However, due to the difficulty in repairing or reusing traditional cross-linked thermosetting materials, the widespread development and application of photopolymer 3D printing will inevitably lead to serious environmental problems or material damage at the end of its lifespan. Rapid self-healing properties are undeniably essential for 3D printing materials.
[0004] Polyurethane acrylates contain thermally reversible urea and acrylate groups, which can be cured and molded using ultraviolet light. Upon heating, the thermally reversible urea groups decompose to form highly reactive -NCO groups. These -NCO groups possess a highly unsaturated bond structure and overlapping arrangement, leading to an electronic resonance effect. This effect results in uneven charge distribution within the group, generating positively charged carbon atoms at the nucleophilic center, thus endowing the -NCO groups with high reactivity. Through a blocking-unblocking reaction, the material can further react with chain extenders to increase the degree of polymerization and improve the overall performance of the material. This process effectively combines ultraviolet thermosetting methods, significantly improving the mechanical properties of the material.
[0005] Based on the above strategy, a series of polyurethane photocurable materials containing dynamic chemical bonds were designed and prepared by introducing dynamically hindered urea bonds into the polyurethane structure using t-BAEMA as a capping agent. t-BAEMA interacts with the -NCO groups in the polyurethane to form reversible, thermally unstable urea bonds. These thermally unstable urea bonds then undergo a decapsulation reaction under heating conditions, regenerating the -NCO groups and allowing further polymerization with a chain extender. This dual curing method, involving both heat and UV light, enhances the mechanical properties of the materials.
[0006] Chinese patent "A Preparation Method of Thermosetting Polyurethane Elastomer for 3D Printing" (Authorization Announcement No.: CN115975146 B, Authorization Announcement Date: 2025.09.02) discloses a method for preparing thermosetting polyurethane elastomer for 3D printing. The method involves quantitatively controlling the polyurethane elastomer with end-capped isocyanate to obtain a one-component thermosetting polyurethane elastomer stock solution. A polyurethane prepolymer is prepared using diisocyanate and oligomeric polyol as raw materials. An end-capping agent containing active hydrogen and the end-capped prepolymer are then used to prepare an end-capped prepolymer. A measured amount of diamine chain extender and catalyst are added to obtain the one-component thermosetting polyurethane elastomer stock solution. The process is relatively complex and cumbersome, and the patent does not investigate the subsequent 3D printing effect or the mechanical properties of the printed parts, making it impossible to assess its applicability as a 3D printing paste. Summary of the Invention
[0007] The purpose of this invention is to provide a method for preparing PUA resin material for 3D printing with photothermal dual-curing properties, which solves the problems of poor stability, low fluidity, defects in printed parts, lack of photothermal dual-curing properties, and difficulty in improving the mechanical properties of printed parts in the prior art.
[0008] To achieve the above objectives, the technical solution of the present invention is as follows: A method for preparing a PUA resin material with photothermal dual-curing properties for 3D printing is specifically implemented according to the following steps: Step 1, Synthesis of PUA prepolymer: Weigh IPDI and PTMG and add them to a three-necked flask. Place the flask in a water bath at 70-80℃ and stir mechanically for 8-10 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh out TBEMA and add it to the PUA prepolymer obtained in step 1. Cool the temperature to 40-50℃ and react for 2-3 hours to obtain photocurable polyurethane acrylate. Step 3, Preparation of silicone chain extender modified polyurethane resin liquid: The photocurable polyurethane acrylate obtained in step 2 is mixed with an amine-terminated silicone chain extender with a relative molecular mass of 2000, and then the reactive diluent TBEMA and photoinitiator are added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. Step 4, DLP photopolymerization 3D printing and thermopolymerization: The silicone chain extender-modified polyurethane resin mixture obtained in step 3 is poured into a photopolymerization 3D printer. The printer parameters are adjusted to perform photopolymerization. After molding, the mixture is cleaned with ethanol and then placed in an oven for thermal curing to obtain a PUA resin material for 3D printing with photothermal dual curing properties.
[0009] Furthermore, the molar ratio of IPDI and PTMG in step 1 is 1:2.
[0010] Furthermore, the molar ratio of TBEMA in step 2 to PTMG in step 1 is 1:1.
[0011] Furthermore, the number of moles of amino groups in the amine-terminated organosilicon chain extender described in step 3 is the same as the number of moles of TBEMA weighed in step 2; the amine-terminated organosilicon chain extender is one or more of primary amine-terminated PDMS-NH2-2000, secondary amine-terminated PDMS, aniline-terminated PDMS, and aminobutyl-terminated PDMS.
[0012] Furthermore, in step 3, TBEMA accounts for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounts for 2-5% of the total mass of polyurethane acrylate and reactive diluent.
[0013] Furthermore, in step 4, the oven temperature is 100-130℃, and the heat curing time is 1-6 hours. Compared with the prior art, the present invention has the following beneficial effects: This invention provides a method for preparing PUA resin materials for 3D printing with photothermal dual-curing properties. Through molecular design, dynamic hindered urea bonds are introduced into the polyurethane structure using TBAEMA end-capping agent, thus preparing a series of polyurethane photocurable materials containing dynamic chemical bonds, solving environmental or material damage problems.
[0014] TBAEMA interacts with the -NCO group in PUA, exhibiting reversible and thermally unstable properties, and possessing simultaneous responsiveness to ultraviolet light and heat.
[0015] The PUA resin synthesized in this invention can be 3D printed using DLP, and its mechanical properties can be controlled by thermosetting at a certain temperature for 1-6 hours. The maximum tensile strength is 1.36 MPa after 4 hours, which is 6.39 times higher than that of unmodified PUA.
[0016] The raw materials used in this preparation process are low-cost and readily available. The PUA resin preparation process has a wide range, good stability, and is easy to mass-produce and store for a long time. Attached Figure Description
[0017] Figure 1 This is a schematic diagram illustrating the synthesis principle of the photocurable polyurethane acrylate of this invention. Figure 2 The infrared spectrum of the photocurable polyurethane acrylate prepared in this invention is shown below. Figure 3 The 1H NMR spectrum of the photocurable polyurethane acrylate prepared in this invention; Figure 4 The TG curves of the primary amine-terminated PDMS-NH2-2000 chain extender-modified polyurethane acrylate prepared in Example 4 of this invention and the polyurethane acrylate without chain extender are shown. Figure 5 The infrared spectra of the PUA resin materials for 3D printing with photothermal dual-curing properties prepared in Examples 1-6 of this invention are shown. Figure 6 The tensile stress-strain curves of the PUA resin materials for 3D printing with photothermal dual-curing properties prepared in Examples 1-6 of the present invention at different times are shown. Figure 7 Comparison of the survival rates of PUA resin materials for 3D printing with photothermal dual-curing properties prepared in Examples 1-5 of this invention and human gingival fibroblasts cultured with polyurethane acrylate without dynamic bonds. Figure 8 These are staining morphology images of live and dead cells in polyurethane acrylate containing dynamic bonds after different thermosetting times, as shown in Examples 1-5 of this invention. Detailed Implementation
[0018] The following is in conjunction with the appendix Figure 1-8 The present invention will be further described in detail below with reference to specific embodiments.
[0019] This invention provides a method for preparing a PUA resin material for 3D printing with dual photothermal curing properties. Through dual modification: firstly, urea bonds are formed by the interaction of TBEMA with the -NCO groups in PUA, resulting in a photocurable polyurethane acrylate. Secondly, the polyurethane resin is modified with an organosilicon chain extender to achieve dual photothermal curing properties. This meets the requirements of DLP-3D printing while solving the problem of poor mechanical properties in PUA-printed parts. Its dual-curing properties effectively improve printing quality and mechanical properties.
[0020] The raw materials used in the preparation process of this invention are low-cost, inexpensive, and readily available. The resin preparation process is stable and controllable, and can be mass-produced.
[0021] A method for preparing a PUA resin material with photothermal dual-curing properties for 3D printing is specifically implemented according to the following steps: Step 1, Synthesis of PUA prepolymer: Weigh isophorone diisocyanate (IPDI) and polytetrahydrofuran diol (PTMG) according to a molar ratio of n(IPDI):n(PTMG) = 1:2. Then add the weighed IPDI and PTMG to a three-necked flask and place it in a water bath at 70-80℃. Stir mechanically for 8-10 h to obtain PUA prepolymer.
[0022] Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh out 2-(tert-butylamino)ethyl methacrylate (TBEMA), with a molar ratio of TBEMA to PTMG in step 1 of 1:1. Add the weighed TBEMA to the PUA prepolymer obtained in step 1, and react in a three-necked flask at 40-50℃ for 2-3 h to obtain photocurable polyurethane acrylate. TBEMA interacts with the -NCO groups in PUA to form urea bonds.
[0023] Step 3, Preparation of silicone chain extender modified polyurethane resin liquid: The photocurable polyurethane acrylate obtained in step 2 is mixed with an amine-terminated silicone chain extender with a relative molecular mass of 2000. The number of molars of amino groups in the silicone chain extender is the same as the number of molars of TBEMA added in step 2. Then, TBEMA, an active diluent, and a photoinitiator are added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. The amine-terminated silicone chain extender is one or more of primary amine-terminated PDMS-NH2-2000, secondary amine-terminated PDMS, aniline-terminated PDMS, and aminobutyl-terminated PDMS. TBEMA accounts for 30% of the total mass of polyurethane acrylate and active diluent, and the photoinitiator accounts for 2-5% of the total mass of polyurethane acrylate and active diluent.
[0024] Step 4, DLP photopolymerization 3D printing and thermopolymerization: Dumbbell-shaped samples (15 mm × 4 mm × 2 mm) and strip-shaped samples (40 mm × 10 mm × 4 mm) were modeled using software and 3D printed. The models were then imported into the instrument's built-in slicing software for slicing and setting the corresponding printing parameters. The sliced models were then imported into the 3D printer. The silicone chain extender-modified polyurethane resin mixture obtained in step 3 was poured into the photopolymerization 3D printer, and the printer parameters were adjusted for photopolymerization. After molding, the samples were cleaned with ethanol and placed in an oven for thermopolymerization at 100-130℃ for 1-6 hours to obtain PUA resin material samples for 3D printing with photothermal dual-curing properties. Example
[0025] Step 1, Synthesis of PUA prepolymer: Based on the molar ratio of n(IPDI):n(PTMG) = 1:2, weigh out isophorone diisocyanate (IPDI) and polytetrahydrofuran diol (PTMG), then add the weighed IPDI and PTMG to a three-necked flask, place it in a water bath at 80°C, and mechanically stir for 8 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh 2-(tert-butylamino)ethyl methacrylate (TBEMA), with a molar ratio of TBEMA to PTMG in step 1 of 1:1. Add the weighed TBEMA to the PUA prepolymer obtained in step 1. TBEMA interacts with the -NCO groups in PUA to form urea bonds. Cool to 50℃ and react for 2 h to obtain photocurable polyurethane acrylate. Step 3, Preparation of the silicone chain extender modified polyurethane resin mixture: The photocurable polyurethane acrylate obtained in step 2 was mixed with PDMS-NH2-2000 with a primary amine-terminated molecular weight of 2000. The molar number of amino groups in the primary amine-terminated PDMS-NH2-2000 was the same as the molar number of TBEMA added in step 2. Then, the reactive diluent TBEMA and the photoinitiator were added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. TBEMA accounted for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounted for 5% of the total mass of polyurethane acrylate and reactive diluent. Step 4, DLP photopolymerization 3D printing and thermosetting: Dumbbell-shaped samples (15 mm × 4 mm × 2 mm) and strip-shaped samples (40 mm × 10 mm × 4 mm) are modeled using software and 3D printed. The models are imported into the instrument's built-in slicing software for slicing and the corresponding printing parameters are set. The sliced models are then imported into the 3D printer. The silicone chain extender-modified polyurethane resin mixture obtained in Step 3 is poured into the photopolymerization 3D printer, and the printer parameters are adjusted for photopolymerization. After molding, the sample is cleaned with ethanol and placed in an oven at 103.6℃ for 1 hour for thermosetting, resulting in a sample printed with PUA resin material for 3D printing with dual photopolymerization properties. Example
[0026] Step 1, Synthesis of PUA prepolymer: Based on the molar ratio of n(IPDI):n(PTMG) = 1:2, weigh out isophorone diisocyanate (IPDI) and polytetrahydrofuran diol (PTMG), then add the weighed IPDI and PTMG to a three-necked flask, place it in a water bath at 80°C, and mechanically stir for 8 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh 2-(tert-butylamino)ethyl methacrylate (TBEMA), with a molar ratio of TBEMA to PTMG in step 1 of 1:1. Add the weighed TBEMA to the PUA prepolymer obtained in step 1. TBEMA interacts with the -NCO groups in PUA to form urea bonds. Cool to 50℃ and react for 2 h to obtain photocurable polyurethane acrylate. Step 3, Preparation of the silicone chain extender modified polyurethane resin mixture: The polyurethane acrylate obtained in step 2 was mixed with primary amine-terminated PDMS-NH2-2000 with a relative molecular mass of 2000. The number of molar amino groups in the primary amine-terminated PDMS-NH2-2000 was the same as the number of molar TBEMA added in step 2. Then, the reactive diluent TBEMA and the photoinitiator were added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. TBEMA accounted for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounted for 5% of the total mass of polyurethane acrylate and reactive diluent. Step 4, DLP photopolymerization 3D printing and thermosetting: Dumbbell-shaped samples (15 mm × 4 mm × 2 mm) and strip-shaped samples (40 mm × 10 mm × 4 mm) are modeled using software and 3D printed. The models are imported into the instrument's built-in slicing software for slicing and the corresponding printing parameters are set. The sliced models are then imported into the 3D printer. The silicone chain extender-modified polyurethane resin mixture obtained in Step 3 is poured into the photopolymerization 3D printer, and the printer parameters are adjusted for photopolymerization. After molding, the sample is cleaned with ethanol and placed in an oven for thermosetting at 103.6℃ for 2 hours to obtain a sample printed with PUA resin material for 3D printing with dual photopolymerization properties. Example
[0027] Step 1, Synthesis of PUA prepolymer: Based on the molar ratio of n(IPDI):n(PTMG) = 1:2, weigh out isophorone diisocyanate (IPDI) and polytetrahydrofuran diol (PTMG), then add the weighed IPDI and PTMG to a three-necked flask, place it in a water bath at 80°C, and mechanically stir for 8 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh 2-(tert-butylamino)ethyl methacrylate (TBEMA), with a molar ratio of TBEMA to PTMG in step 1 of 1:1. Add the weighed TBEMA to the PUA prepolymer obtained in step 1. TBEMA interacts with the -NCO groups in PUA to form urea bonds. Cool to 50℃ and react for 2 h to obtain photocurable polyurethane acrylate. Step 3, Preparation of the silicone chain extender modified polyurethane resin mixture: The polyurethane acrylate obtained in step 2 was mixed with primary amine-terminated PDMS-NH2-2000 with a relative molecular mass of 2000. The number of molar amino groups in the primary amine-terminated PDMS-NH2-2000 was the same as the number of molar TBEMA added in step 2. Then, the reactive diluent TBEMA and the photoinitiator were added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. TBEMA accounted for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounted for 5% of the total mass of polyurethane acrylate and reactive diluent. Step 4, DLP photopolymerization 3D printing and thermosetting: Dumbbell-shaped samples (15 mm × 4 mm × 2 mm) and strip-shaped samples (40 mm × 10 mm × 4 mm) are modeled using software and 3D printed. The models are imported into the instrument's built-in slicing software for slicing and the corresponding printing parameters are set. The sliced models are then imported into the 3D printer. The silicone chain extender-modified polyurethane resin mixture obtained in Step 3 is poured into the photopolymerization 3D printer, and the printer parameters are adjusted for photopolymerization. After molding, the sample is cleaned with ethanol and placed in an oven for thermosetting at 103.6℃ for 3 hours to obtain a sample printed with PUA resin material for 3D printing with dual photopolymerization properties. Example
[0028] Step 1, Synthesis of PUA prepolymer: Based on the molar ratio of n(IPDI):n(PTMG) = 1:2, weigh out isophorone diisocyanate (IPDI) and polytetrahydrofuran diol (PTMG), then add the weighed IPDI and PTMG to a three-necked flask, place it in a water bath at 80°C, and mechanically stir for 8 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh 2-(tert-butylamino)ethyl methacrylate (TBEMA), with a molar ratio of TBEMA to PTMG in step 1 of 1:1. Add the weighed TBEMA to the PUA prepolymer obtained in step 1. TBEMA interacts with the -NCO groups in PUA to form urea bonds. Cool to 50℃ and react for 2 h to obtain photocurable polyurethane acrylate. Step 3, Preparation of the silicone chain extender modified polyurethane resin mixture: The polyurethane acrylate obtained in step 2 was mixed with primary amine-terminated PDMS-NH2-2000 with a relative molecular mass of 2000. The number of molar amino groups in the primary amine-terminated PDMS-NH2-2000 was the same as the number of molar TBEMA added in step 2. Then, the reactive diluent TBEMA and the photoinitiator were added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. TBEMA accounted for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounted for 5% of the total mass of polyurethane acrylate and reactive diluent. Step 4, DLP photopolymerization 3D printing and thermosetting: Dumbbell-shaped samples (15 mm × 4 mm × 2 mm) and strip-shaped samples (40 mm × 10 mm × 4 mm) are modeled using software and 3D printed. The models are imported into the instrument's built-in slicing software for slicing and the corresponding printing parameters are set. The sliced models are then imported into the 3D printer. The silicone chain extender-modified polyurethane resin mixture obtained in Step 3 is poured into the photopolymerization 3D printer, and the printer parameters are adjusted for photopolymerization. After molding, the sample is cleaned with ethanol and placed in an oven for thermosetting at 103.6℃ for 4 hours to obtain a sample printed with PUA resin material for 3D printing with dual photopolymerization properties. Example
[0029] Step 1, Synthesis of PUA prepolymer: Based on the molar ratio of n(IPDI):n(PTMG) = 1:2, weigh out isophorone diisocyanate (IPDI) and polytetrahydrofuran diol (PTMG), then add the weighed IPDI and PTMG to a three-necked flask, place it in a water bath at 80°C, and mechanically stir for 8 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh 2-(tert-butylamino)ethyl methacrylate (TBEMA), with a molar ratio of TBEMA to PTMG in step 1 of 1:1. Add the weighed TBEMA to the PUA prepolymer obtained in step 1. TBEMA interacts with the -NCO groups in PUA to form urea bonds. Cool to 50℃ and react for 2 h to obtain photocurable polyurethane acrylate. Step 3, Preparation of silicone chain extender modified polyurethane resin mixture: The polyurethane acrylate obtained in step 2 was mixed with primary amine-terminated PDMS-NH2-2000 with a relative molecular mass of 2000. The number of molar amino groups in the primary amine-terminated PDMS-NH2-2000 was the same as the number of molar TBEMA added in step 2. Then, the reactive diluent TBEMA and the photoinitiator were added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. TBEMA accounted for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounted for 5% of the total mass of polyurethane acrylate and reactive diluent. Step 4, DLP photopolymerization 3D printing and thermopolymerization: Dumbbell-shaped samples (15 mm × 4 mm × 2 mm) and strip-shaped samples (40 mm × 10 mm × 4 mm) were modeled using software and 3D printed. The models were then imported into the instrument's built-in slicing software for slicing and setting the corresponding printing parameters. The sliced models were then imported into the 3D printer. The silicone chain extender-modified polyurethane resin mixture obtained in step 3 was poured into the photopolymerization 3D printer, and the printer parameters were adjusted for photopolymerization. After molding, the samples were cleaned with ethanol and placed in an oven at 103.6℃ for 5 hours for thermopolymerization, resulting in PUA resin material samples for 3D printing with photothermal dual-curing properties. Example
[0030] Step 1, Synthesis of PUA prepolymer: Based on the molar ratio of n(IPDI):n(PTMG) = 1:2, weigh out isophorone diisocyanate (IPDI) and polytetrahydrofuran diol (PTMG), then add the weighed IPDI and PTMG to a three-necked flask, place it in a water bath at 80°C, and mechanically stir for 8 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh 2-(tert-butylamino)ethyl methacrylate (TBEMA), with a molar ratio of TBEMA to PTMG in step 1 of 1:1. Add the weighed TBEMA to the PUA prepolymer obtained in step 1. TBEMA interacts with the -NCO groups in PUA to form urea bonds. Cool to 50℃ and react for 2 h to obtain photocurable polyurethane acrylate. Step 3, Preparation of the silicone chain extender modified polyurethane resin mixture: The polyurethane acrylate obtained in step 2 was mixed with primary amine-terminated PDMS-NH2-2000 with a relative molecular mass of 2000. The number of molar amino groups in the primary amine-terminated PDMS-NH2-2000 was the same as the number of molar TBEMA added in step 2. Then, the reactive diluent TBEMA and the photoinitiator were added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. TBEMA accounted for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounted for 5% of the total mass of polyurethane acrylate and reactive diluent. Step 4, DLP photopolymerization 3D printing and thermosetting: Dumbbell-shaped samples (15 mm × 4 mm × 2 mm) and strip-shaped samples (40 mm × 10 mm × 4 mm) are modeled using software and 3D printed. The models are imported into the instrument's built-in slicing software for slicing and the corresponding printing parameters are set. The sliced models are then imported into the 3D printer. The silicone chain extender-modified polyurethane resin mixture obtained in Step 3 is poured into the photopolymerization 3D printer, and the printer parameters are adjusted for photopolymerization. After molding, the sample is cleaned with ethanol and placed in an oven for thermosetting at 103.6℃ for 6 hours to obtain a sample printed with PUA resin material for 3D printing with dual photopolymerization properties. Example
[0031] Step 1, Synthesis of PUA prepolymer: Based on the molar ratio of n(IPDI):n(PTMG) = 1:2, weigh out isophorone diisocyanate (IPDI) and polytetrahydrofuran diol (PTMG), then add the weighed IPDI and PTMG to a three-necked flask, place it in a water bath at 70°C, and mechanically stir for 10 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh out 2-(tert-butylamino)ethyl methacrylate (TBEMA). The molar ratio of TBEMA to PTMG in step 1 is 1:1. Add the weighed TBEMA to the PUA prepolymer obtained in step 1. TBEMA interacts with the -NCO groups in PUA to form urea bonds. Cool to 50℃ and react for 3 h to obtain photocurable polyurethane acrylate. Step 3, Preparation of the silicone chain extender modified polyurethane resin mixture: The polyurethane acrylate obtained in step 2 was mixed with secondary amine-terminated PDMS with a relative molecular mass of 2000. The molar number of amino groups in the secondary amine-terminated PDMS was the same as the molar number of TBEMA added in step 2. Then, the reactive diluent TBEMA and the photoinitiator were added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. TBEMA accounted for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounted for 5% of the total mass of polyurethane acrylate and reactive diluent. Step 4, DLP photopolymerization 3D printing and thermosetting: Dumbbell-shaped samples (15 mm × 4 mm × 2 mm) and strip-shaped samples (40 mm × 10 mm × 4 mm) are modeled using software and 3D printed. The models are imported into the instrument's built-in slicing software for slicing and the corresponding printing parameters are set. The sliced models are then imported into the 3D printer. The silicone chain extender-modified polyurethane resin mixture obtained in Step 3 is poured into the photopolymerization 3D printer, and the printer parameters are adjusted for photopolymerization. After molding, the sample is cleaned with ethanol and placed in an oven at 110.5℃ for 4 hours for thermosetting, resulting in a sample printed with PUA resin material for 3D printing with dual photopolymerization properties. Example
[0032] Step 1, Synthesis of PUA prepolymer: Based on the molar ratio of n(IPDI):n(PTMG) = 1:2, weigh out isophorone diisocyanate (IPDI) and polytetrahydrofuran diol (PTMG), then add the weighed IPDI and PTMG to a three-necked flask, place it in a water bath at 75°C, and mechanically stir for 9 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh out 2-(tert-butylamino)ethyl methacrylate (TBEMA), with a molar ratio of TBEMA to PTMG in step 1 of 1:1. Add the weighed TBEMA to the PUA prepolymer obtained in step 1. TBEMA interacts with the -NCO groups in PUA to form urea bonds. Cool to 45℃ and react for 2 h to obtain photocurable polyurethane acrylate. Step 3, Preparation of the silicone chain extender modified polyurethane resin mixture: The polyurethane acrylate obtained in step 2 was mixed with aniline-terminated PDMS with a relative molecular mass of 2000. The molar number of amino groups in the aniline-terminated PDMS was the same as the molar number of TBEMA added in step 2. Then, the reactive diluent TBEMA and the photoinitiator were added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. TBEMA accounted for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounted for 5% of the total mass of polyurethane acrylate and reactive diluent. Step 4, DLP photopolymerization 3D printing and thermosetting: Dumbbell-shaped samples (15 mm × 4 mm × 2 mm) and strip-shaped samples (40 mm × 10 mm × 4 mm) are modeled using software and 3D printed. The models are imported into the instrument's built-in slicing software for slicing and the corresponding printing parameters are set. The sliced models are then imported into the 3D printer. The silicone chain extender-modified polyurethane resin mixture obtained in Step 3 is poured into the photopolymerization 3D printer, and the printer parameters are adjusted for photopolymerization. After molding, the sample is cleaned with ethanol and placed in an oven for thermosetting at 130℃ for 4 hours to obtain a sample printed with PUA resin material for 3D printing with dual photopolymerization properties. Example
[0033] Step 1, Synthesis of PUA prepolymer: Based on the molar ratio of n(IPDI):n(PTMG) = 1:2, weigh out isophorone diisocyanate (IPDI) and polytetrahydrofuran diol (PTMG), then add the weighed IPDI and PTMG to a three-necked flask, place it in a water bath at 75°C, and mechanically stir for 9 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh out 2-(tert-butylamino)ethyl methacrylate (TBEMA), with a molar ratio of TBEMA to PTMG in step 1 of 1:1. Add the weighed TBEMA to the PUA prepolymer obtained in step 1. TBEMA interacts with the -NCO groups in PUA to form urea bonds. Cool to 40℃ and react for 3 h to obtain photocurable polyurethane acrylate. Step 3, Preparation of the silicone chain extender modified polyurethane resin mixture: The polyurethane acrylate obtained in step 2 was mixed with aminobutylated PDMS with a relative molecular mass of 2000. The molar number of amino groups in the aminobutylated PDMS was the same as the molar number of TBEMA added in step 2. Then, the reactive diluent TBEMA and the photoinitiator were added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. TBEMA accounted for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounted for 5% of the total mass of polyurethane acrylate and reactive diluent. Step 4, DLP photopolymerization 3D printing and thermosetting: Dumbbell-shaped samples (15 mm × 4 mm × 2 mm) and strip-shaped samples (40 mm × 10 mm × 4 mm) are modeled using software and 3D printed. The models are imported into the instrument's built-in slicing software for slicing and the corresponding printing parameters are set. The sliced models are then imported into the 3D printer. The silicone chain extender-modified polyurethane resin mixture obtained in Step 3 is poured into the photopolymerization 3D printer, and the printer parameters are adjusted for photopolymerization. After molding, the sample is cleaned with ethanol and placed in an oven for thermosetting at 100℃ for 4 hours to obtain a sample printed with PUA resin material for 3D printing with dual photopolymerization properties.
[0034] Figure 1 This is a schematic diagram illustrating the synthesis principle of the photocurable polyurethane acrylate of this invention. From... Figure 1 As can be seen, IPDI and PTMG were first added to a three-necked flask and reacted in a water bath at 80°C to obtain a polyurethane prepolymer. Then, the temperature was lowered to 50°C, TBEMA was added, and the reaction continued for 2 hours to obtain a photocurable polyurethane acrylate.
[0035] Figure 2 The image shows the infrared spectrum of the photocurable polyurethane acrylate prepared according to this invention. Figure 2 It can be seen from this that 3200-3400 cm -1 A broad peak exists, which is the stretching vibration peak of the NH bond in the urethane group (-NH-CO-O-). 2800-3000 cm⁻¹ -1 The absorption peak at 1700-1740 cm⁻¹ corresponds to the stretching vibration peak of saturated -CH- in photocurable polyurethane, indicating the presence of an alkyl chain in the molecule. -1 The peak at 1000-1300 cm⁻¹ corresponds to the stretching vibration of the carbonyl group (-C=O) in carbamate esters. -1 The absorption peak at 2270 cm⁻¹ corresponds to the -COC- stretching vibration peak in the photocurable polytetrahydrofuran polyurethane. -1 The peak (isocyanate-NCO stretching) indicates that the -NCO reaction was complete in the synthesis reaction, and the peak at 1636 cm⁻¹ further supports this. -1 The presence of a double bond (-C=C-) absorption peak indicates the successful synthesis of photocurable polyurethane acrylate.
[0036] Figure 3 The 1H NMR spectrum of the photocurable polyurethane acrylate prepared in this invention. Figure 3As shown, 6.12 ppm and 5.63 ppm represent hydrogen atoms from the trans-C=C and cis-double bonds in 2-(tert-butylamino)ethyl methacrylate, 1.42 ppm represents hydrogen atoms from the tert-butyl group in 2-(tert-butylamino)ethyl methacrylate, 7.26 ppm represents hydrogen atoms from the urethane group in the photocurable polyurethane structure, 3.41 ppm and 1.61 ppm represent hydrogen atoms from the -CH2 group in polytetrahydrofuran, and 3.41 ppm, 2.91 ppm, 1.06 ppm and 0.92 ppm represent hydrogen atoms from the -CH2, -CH and -CH3 groups in the isophorone diisocyanate alicyclic structure. These results further confirm the successful synthesis of the desired photocurable polyurethane acrylate.
[0037] Figure 4 The TG curves of the amine-terminated PDMS-NH2-2000 chain extender-modified polyurethane acrylate prepared in Example 4 of this invention and the polyurethane acrylate without the chain extender are shown in Table 1. Figure 4 As shown in Table 1, the thermal stability of PDMS-NH2-2000 / PUA is improved compared to PUA after the addition of organosilicon chain extender. The initial decomposition temperature (T) of PDMS-NH2-2000 / PUA is lower. 5% The thermal stability of the polyurethane acrylate was 275.38℃, a 2.97% increase compared to PUA's 267.42℃. Simultaneously, the residual carbon content at 600℃ increased to 3.03%, further demonstrating that the addition of the silicone chain extender can improve the thermal stability of polyurethane acrylate. This is because the PUA backbone with the added chain extender contains -Si-C- and -Si-O-Si- bonds, which require more energy to decompose upon heating than -CH- bonds, thus improving the heat resistance of the polyurethane acrylate. Furthermore, the introduction of the chain extender leads to re-thermal curing, increasing the degree of polymerization and crosslinking density of the polyurethane acrylate system, resulting in improved thermal stability.
[0038] Table 1. TG curve parameters of amine-terminated PDMS-NH2-2000 chain extender-modified polyurethane acrylates and polyurethane acrylates without chain extender.
[0039] Figure 5 (a) is the infrared spectrum analysis diagram of the PUA resin material for 3D printing with photothermal dual-curing properties prepared in Examples 1-6 of this invention. Figure 5 (b) The figure is Figure 5 (a) is a magnified view of the infrared spectrum. (From...) Figure 5 (a) It can be seen that 860-760 cm -1 The peak at 1280-1250 cm⁻¹ is the planar rocking vibration peak of -Si-CH₃ in PDMS-NH₂. -1The sharp peak at 1090-1020 cm⁻¹ is the deformation vibration peak of Si-symmetric -CH₃. -1 The peak at 1085 cm⁻¹ is the stretching vibration peak of the -Si-O-Si- bond, while the absorption peak of the siloxane chain is close to 1085 cm⁻¹. -1 and 1020 cm -1 . Figure 5 (b) It can be seen that with the increase of thermosetting time, the intensity of the absorption vibration peaks of -Si-CH3 and -Si-O-Si- increases, indirectly indicating that the content of urea groups generated by the thermosetting chain extension reaction increases. At the same time, it was found that the intensity of the peaks at these positions increased by PDMS-NH2-2000 / PUA. This is because the longer the chain length, the greater the intensity of the absorption vibration peaks of -Si-CH3 and -Si-O-Si-. Therefore, PDMS-NH2-2000 participated in the thermosetting reaction and successfully extended the chain.
[0040] Figure 6 The figures show the tensile stress-strain curves of the photothermal dual-curing PUA resin materials for 3D printing prepared in Examples 1-6 of this invention at different times. As shown in Table 2, the mechanical properties of the material after thermocuring are significantly improved compared to the uncured material. By comparing the effects of different thermocuring times on the mechanical properties of the composite material, from 1 h to 6 h, the PDMS-NH2-2000 / PUA sample exhibited the best mechanical properties and the highest tensile strength (1.36 MPa) at a thermocuring time of 4 h, which is 6.39 times higher than that of PUA without the chain extender. This is because the primary amine-terminated PDMS-NH2-2000 underwent a chain extension reaction during thermocuring, increasing the crosslinking density between PUA molecular chains and thus significantly improving the material's mechanical properties. Therefore, selecting the primary amine-terminated PDMS-NH2-2000 as the chain extender and thermocuring for 4 h resulted in the PDMS-NH2-2000 / PUA exhibiting the best mechanical properties.
[0041] Table 2 Mechanical properties of PUA printed parts with different thermosetting times after adding primary amine-terminated PDMS-NH2-2000
[0042] Figure 7This image shows a comparison of the survival rates of human gingival fibroblasts cultured with PUA resin materials for 3D printing with photothermal dual-curing properties prepared in Examples 1-5 of this invention and those with polyurethane acrylate containing dynamic bonds. Human gingival fibroblasts (HGF) were co-cultured using the CCK 8 method with polyurethane acrylate containing dynamic bonds (control group) and polyurethane acrylate culture medium with thermosetting times of 0, 1, 2, 3, 4, and 5 h (experimental group). Cell proliferation results were obtained after 24 h and 48 h of culture. Comparing the cell survival rates of the control and experimental groups, the experimental group showed a significant increase in the number of proliferating cells compared to the control group, and the cell survival rate of the experimental group was greater than 100%, indicating that polyurethane acrylate containing dynamic bonds with different thermosetting times promoted cell proliferation without toxicity.
[0043] Figure 8 The images show the morphological characteristics of live and dead cells in polyurethane acrylate containing dynamic bonds after different heat curing times in Examples 1-5 of this invention. In the images, (A) represents 0 h of heat curing; (B) represents 1 h of heat curing; (C) represents 2 h of heat curing; (D) represents 3 h of heat curing; (E) represents 4 h of heat curing; and (F) represents 5 h of heat curing. 0 represents live cells, and 1 represents dead cells. Figures (A0) and (A1) show the staining morphology of live and dead cells containing dynamic bond polyurethane acrylate after 0 hours of heat curing; Figures (B0) and (B1) show the staining morphology of live and dead cells containing dynamic bond polyurethane acrylate after 1 hour of heat curing; Figures (C0) and (C1) show the staining morphology of live and dead cells containing dynamic bond polyurethane acrylate after 2 hours of heat curing; Figures (D0) and (D1) show the staining morphology of live and dead cells containing dynamic bond polyurethane acrylate after 3 hours of heat curing; Figures (E0) and (E1) show the staining morphology of live and dead cells containing dynamic bond polyurethane acrylate after 4 hours of heat curing; Figures (F0) and (F1) show the staining morphology of live and dead cells containing dynamic bond polyurethane acrylate after 5 hours of heat curing; Figures (A0), (B0), (C0), (D0), (E0), and (F0) show the staining morphology of live cells containing dynamic bond polyurethane acrylate; Figures (A1), (B1), (C1), (D1), (E1), and (F1) show the staining morphology of dead cells containing dynamic bond polyurethane acrylate. Comparing the staining morphology of dead and live cells in the images, it was found that the red dots representing dead cells in the materials containing dynamic polyurethane acrylate with heat curing times of 0, 1, 2, 3, 4 and 5 hours were very few, while the green dots representing live cells were very many. This indicates that the cell survival rate is much higher than the mortality rate, suggesting that the materials containing dynamic polyurethane acrylate have good biocompatibility.
[0044] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.
Claims
1. A method for preparing a PUA resin material for 3D printing with photothermal dual-curing properties, characterized in that, The specific steps are as follows: Step 1, Synthesis of PUA prepolymer: Weigh IPDI and PTMG and add them to a three-necked flask. Place the flask in a water bath at 70-80℃ and stir mechanically for 8-10 hours to obtain PUA prepolymer. Step 2, Synthesis of UV-cured polyurethane acrylate: Weigh out TBEMA and add it to the PUA prepolymer obtained in step 1. Cool the temperature to 40-50℃ and react for 2-3 hours to obtain photocurable polyurethane acrylate. Step 3, Preparation of silicone chain extender modified polyurethane resin liquid: The photocurable polyurethane acrylate obtained in step 2 is mixed with an amine-terminated silicone chain extender with a relative molecular mass of 2000, and then the reactive diluent TBEMA and photoinitiator are added and mechanically stirred to prepare a polyurethane resin mixture, which is the silicone chain extender modified polyurethane resin mixture. Step 4, DLP photopolymerization 3D printing and thermopolymerization: The silicone chain extender-modified polyurethane resin mixture obtained in step 3 is poured into a photopolymerization 3D printer. The printer parameters are adjusted to perform photopolymerization. After molding, the mixture is cleaned with ethanol and then placed in an oven for thermal curing to obtain a PUA resin material for 3D printing with photothermal dual curing properties.
2. The method for preparing a PUA resin material for 3D printing with photothermal dual-curing properties according to claim 1, characterized in that, The molar ratio of IPDI and PTMG in step 1 is 1:
2.
3. The method for preparing a PUA resin material for 3D printing with photothermal dual-curing properties according to claim 1, characterized in that, The molar ratio of TBEMA in step 2 to PTMG in step 1 is 1:
1.
4. The method for preparing a PUA resin material with photothermal dual-curing properties for 3D printing according to claim 1, characterized in that, The number of moles of amino groups in the amine-terminated organosilicon chain extender mentioned in step 3 is the same as the number of moles of TBEMA weighed in step 2; the amine-terminated organosilicon chain extender is one or more of the following: primary amine-terminated PDMS-NH2-2000, secondary amine-terminated PDMS, aniline-terminated PDMS, and aminobutyl-terminated PDMS.
5. The method for preparing a PUA resin material for 3D printing with photothermal dual-curing properties according to claim 1, characterized in that, In step 3, TBEMA accounts for 30% of the total mass of polyurethane acrylate and reactive diluent, and the photoinitiator accounts for 2-5% of the total mass of polyurethane acrylate and reactive diluent.
6. The method for preparing a PUA resin material for 3D printing with photothermal dual-curing properties according to claim 1, characterized in that, In step 4, the oven temperature is 100-130℃, and the heat curing time is 1-6 hours.