Silver-loaded graft modified polyurethane acrylate oligomer, 3D printing resin composition containing same and application

Abstract

The invention discloses a silver-loaded graft modified polyurethane acrylate oligomer, a 3D printing resin composition containing the same and application, the silver-loaded graft modified polyurethane acrylate oligomer is obtained by functionalizing polyethyleneimine, complexing with silver ions and grafting to polyurethane acrylate, and when light-cured resin is prepared and used for 3D printing of surgical guide plates, the silver-loaded graft modified polyurethane acrylate oligomer has the advantages that the silver-loaded graft modified polyurethane acrylate oligomer can be used for 3D printing of surgical guide plates; and meanwhile, the material has internal long-acting antibacterial and enhanced mechanical properties, and has a wide application prospect in the field of personalized medical apparatuses and instruments.

Description

Technical Field

[0001] This invention relates to the field of 3D printing resin technology, specifically to silver-grafted modified polyurethane acrylate oligomers, 3D printing resin compositions containing the same and their applications. Background Technology

[0002] Photopolymer 3D printing technology has rapidly developed in many fields such as industrial parts, molds, aerospace, and medical. Among them, personalized surgical guides, as one of the more successful clinical applications, have been widely used in neurosurgery, maxillofacial surgery, orthopedics, and dental implantology.

[0003] However, the material properties used to manufacture surgical guides, especially their biosafety performance, have become a bottleneck restricting the further development of this technology. Currently, mainstream 3D printing photocurable resins on the market are primarily designed with printing accuracy, curing speed, and mechanical strength in mind, while generally lacking crucial antibacterial properties. This necessitates that guides made from these materials undergo rigorous terminal sterilization before clinical use.

[0004] Currently, sterilization methods for commercially available 3D-printed surgical guides primarily rely on ethylene oxide gas sterilization and low-temperature plasma sterilization. While these two methods are widely used, their inherent drawbacks cannot be ignored. Although ethylene oxide sterilization is thorough, its entire cycle takes several hours to over ten hours, which cannot meet the needs of emergency or rapid-turnaround surgeries. More importantly, ethylene oxide, as a toxic gas, has a strong adsorption and penetration capacity in porous polymer materials. If the desorption is insufficient, residual toxic substances may cause allergies, inflammation, or even carcinogenic risks to patient tissues, posing a potential threat to both doctors and patients. In contrast, low-temperature plasma sterilization is favored due to its low operating temperature, short cycle, and lack of toxic residues, making it the first choice for many hospitals. However, the working principle of this method dictates that its bactericidal effects (such as active free radicals and ultraviolet light) can only act on the outer surface of the instrument. For dense, non-porous polymer materials such as photocurable resins, its effects cannot penetrate and reach the interior of the material.

[0005] This "surface sterilization" characteristic harbors a significant risk of infection in the practical application of surgical guides. Surgical guides, especially positioning guides in orthopedic surgery, are designed to closely adhere to the bone surface during surgery and guide high-speed rotating instruments such as drills and oscillating saws. During this process, the edges of the guide are inevitably cut and abraded by the instruments, exposing the unsterilized material and generating a large amount of polymer debris at the micron or even nanometer scale. This debris can also be contaminated with bacteria (such as Staphylococcus aureus and Escherichia coli) from the surgical environment and can directly enter the depths of the surgical wound along with instrument manipulation and physiological irrigation fluids. Because these are foreign bodies carrying bacteria, the body's immune system has difficulty completely eliminating them, easily becoming foci of infection and leading to serious complications such as deep tissue infection and osteomyelitis.

[0006] Therefore, current technology faces a dilemma: guide plates without antibacterial function pose a risk of postoperative infection, while guide plates that simply add antibacterial agents physically face new problems such as unstable efficacy, potential toxicity, and promotion of drug resistance.

[0007] In summary, the development of a novel photocurable resin material must simultaneously meet three core requirements: First, it must possess long-lasting and stable intrinsic antibacterial properties derived from the material itself, ensuring that even when the guide plate is damaged, the newly exposed surface inside can effectively inhibit bacterial growth; second, it must maintain excellent photocurable 3D printing suitability and mechanical properties to meet the stringent precision and strength requirements of surgical guide plates; and third, through material design, it must fundamentally solve the problems of antibacterial agent dispersion, fixation, and controlled release, avoiding biosafety risks. Summary of the Invention

[0008] This invention provides silver-grafted modified polyurethane acrylate oligomers to meet the need for preparing antimicrobial products in 3D printing resins, thereby at least addressing one of the many deficiencies in the prior art.

[0009] In view of this, the solution of the present invention is as follows: The first aspect of the present invention is to provide a silver-grafted modified polyurethane acrylate oligomer having the general structural formula shown in Formula I: ; R1 represents a carbon chain, and PUA represents polyurethane acrylate.

[0010] A second aspect of the present invention is to provide a method for preparing the silver-loaded grafted modified polyurethane acrylate oligomer described in the first aspect, comprising the steps of: S1. Polyethyleneimine and a carboxyl-containing acrylate undergo a condensation reaction under polar aprotic solvent and catalyst conditions to obtain polyethyleneimine containing double bonds; the structural formula of the carboxyl-containing acrylate is: R1 is a carbon chain; Under light-protected conditions, silver nitrate was added to the reaction solution to carry out a complexation reaction, and silver-loaded polyethyleneimine complex was obtained by precipitation. S2. The silver-loaded polyethyleneimine complex obtained in step S1 is reacted with the hydroxyl-containing polyurethane acrylate oligomer by melt polycondensation under the action of catalyst two to obtain the silver-loaded grafted modified polyurethane acrylate oligomer.

[0011] In a preferred embodiment, in step S1: The polar aprotic solvent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, or dimethyl sulfoxide; the non-solvent is at least one of diethyl ether, acetone, or n-hexane. And / or, the catalyst one is p-toluenesulfonic acid; And / or, the molar ratio of the polyethyleneimine to the carboxyl-containing acrylate is 1:(0.8-1.2). And / or, the reaction process is carried out under a protective atmosphere, at a reaction temperature of 70-85°C, for 4-8 hours.

[0012] Furthermore, in step S1: The molar ratio of silver nitrate to polyethyleneimine is (0.05-0.15):1; And / or, the complexation reaction is carried out at a temperature of 20-30°C for 3-5 hours; And / or, the precipitation process is carried out in a non-solvent environment. Furthermore, in step S2: The mass ratio of the silver-loaded polyethyleneimine complex to the hydroxyl-containing polyurethane acrylate oligomer is (15-25):100; the hydroxyl-containing polyurethane acrylate oligomer is a polyurethane acrylate oligomer with hydroxyl functional groups in the main chain or any branch chain. And / or, the catalyst two is dibutyltin dilaurate.

[0013] A third aspect of the present invention is to provide an antibacterial 3D printing resin composition, comprising, by weight, 15-25 parts of silver-grafted modified polyurethane acrylate oligomer, 45-60 parts of unmodified polyurethane acrylate oligomer, 20-30 parts of reactive diluent, 1.5-2.5 parts of photoinitiator, and 0.5-1.0 parts of co-initiator; wherein the silver-grafted modified polyurethane acrylate oligomer is the silver-grafted modified polyurethane acrylate oligomer described in the first aspect or the silver-grafted modified polyurethane acrylate oligomer prepared by the preparation method described in the second aspect.

[0014] Furthermore, the photoinitiator is at least one of benzophenone, 2-isopropylthioxanthone and its derivatives; and / or, the co-initiator is methyldiethanolamine.

[0015] A fourth aspect of the present invention is to provide a method for preparing the 3D printing resin composition described in the third aspect, wherein the components are taken in parts by weight and stirred at 50-65°C in the dark for at least 30 minutes.

[0016] A fifth aspect of the present invention is to provide a 3D printed part obtained by photocuring a resin composition described in the third aspect or a resin composition obtained by the preparation method described in the fourth aspect.

[0017] A sixth aspect of the present invention is to provide a surgical guide plate obtained by 3D printing and photocuring of a resin composition described in the third aspect or a resin composition obtained by the preparation method described in the fourth aspect, or by 3D printing of a 3D printed part described in the fifth aspect.

[0018] Compared with the prior art, the present invention has the following beneficial effects: The silver-grafted modified polyurethane acrylate oligomer provided by this invention achieves simultaneous introduction of active double bonds and construction of silver ion complexing sites by grafting carboxyl-containing acrylates onto the polyethyleneimine molecular chain. Then, through melt polycondensation, the silver-loaded functional groups are chemically bonded to the polyurethane acrylate backbone, forming a stable microscopic phase-separated structure. The polyethyleneimine segments form stable coordination with silver ions through their abundant amine groups, and the carboxyl groups provided by the carboxyl-containing acrylate further enhance the complexing stability. During photocuring, the active free radicals generated by the co-initiator methyl diethanolamine can reduce silver ions to nano-silver in situ, achieving molecular-level dispersion and stable anchoring of nano-silver in the resin matrix. When formulated into a photocurable resin for 3D printing surgical guides, the uniformly distributed nano-silver within imparts antibacterial properties to the material. Even when the guide is drilled during surgery, generating internal debris, the newly exposed surface maintains durable antibacterial properties, effectively preventing the risk of deep tissue infection.

[0019] In the internal antibacterial photocurable resin of the present invention, a rigid polyethyleneimine-silver complex is used as a reinforcing phase and is uniformly dispersed in a flexible polyurethane acrylate network through chemical bonds to form a micro-composite reinforcing structure. This significantly improves the tensile modulus and flexural strength of the material, enabling the prepared surgical guide to better maintain shape stability during surgery and improve surgical precision.

[0020] The photocurable resin system of this invention has good compatibility and excellent light transmittance, making it suitable for high-precision photocurable 3D printing. The surgical guide plate prepared has high surface quality and good dimensional stability, while also possessing long-lasting internal antibacterial properties and enhanced mechanical properties, showing broad application prospects in the field of personalized medical devices. Detailed Implementation

[0021] The technical solution of the present invention will now be clearly and completely described in conjunction with preferred embodiments. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] In one embodiment, a silver-grafted modified polyurethane acrylate oligomer is provided, having the following structure: [Polyurethane acrylate segment]-linking group-[silver-loaded polyethyleneimine segment·(A ) n - (meth)acrylate end groups that can participate in photocuring reactions.

[0023] The optional structural formula is shown in Formula I:

[0024] In Formula I, R1 is a carbon chain, and PUA represents polyurethane acrylate.

[0025] In the above embodiments, the provided silver-loaded grafted modified polyurethane acrylate oligomer achieves simultaneous introduction of active double bonds and construction of silver ion complexing sites by grafting carboxyl-containing acrylates onto the polyethyleneimine molecular chain. Then, through melt polycondensation, the silver-loaded functional groups are chemically bonded to the polyurethane acrylate backbone, forming a stable microscopic phase-separated structure. The polyethyleneimine segments form stable coordination with silver ions through their abundant amine groups, and the carboxyl groups provided by the carboxyl-containing acrylate further enhance the complexing stability. During photocuring, the active free radicals generated by the co-initiator methyl diethanolamine can reduce silver ions to nano-silver in situ, achieving molecular-level dispersion and stable anchoring of nano-silver in the resin matrix. When the photocurable resin is used for 3D printing surgical guides, the uniformly distributed nano-silver within it imparts antibacterial properties to the material. When the guide is drilled during surgery, generating internal debris, the newly exposed surface maintains durable antibacterial properties, effectively preventing the risk of deep tissue infection.

[0026] In another embodiment, a method for preparing silver-grafted modified polyurethane acrylate oligomers is proposed, comprising the following steps: S1. Polyethyleneimine and carboxyl-containing acrylates are grafted together in a polar aprotic solvent and under an inert atmosphere at 70-85°C for 4-8 hours, resulting in a condensation reaction to yield polyethyleneimine containing double bonds. After the reaction, the system is cooled to room temperature. The structural formula of the carboxyl-containing acrylate is as follows: R1 is a carbon chain; Continue stirring, add silver nitrate, and carry out the silver ion complexation reaction at 20-30℃ for 3-5 hours. Then precipitate in a non-solvent, separate and vacuum dry to obtain silver-loaded polyethyleneimine complex with terminal double bonds. S2. The silver-loaded polyethyleneimine complex obtained in step S1 is reacted with the hydroxyl-containing polyurethane acrylate oligomer by melt polycondensation under the action of catalyst two to obtain the silver-loaded grafted modified polyurethane acrylate oligomer.

[0027] In a preferred embodiment, the catalyst is p-toluenesulfonic acid, the polar aprotic solvent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, or dimethyl sulfoxide; the non-solvent is at least one of diethyl ether, acetone, or n-hexane; and the molar ratio of polyethyleneimine, carboxyl-containing acrylate, and silver nitrate is 1:(0.8-1.2):(0.05-0.15). In a preferred embodiment, the mass ratio of the silver-loaded polyethyleneimine complex to the hydroxyl-containing polyurethane acrylate oligomer is (15-25):100; the hydroxyl-containing polyurethane acrylate oligomer is a polyurethane acrylate oligomer with hydroxyl functional groups in its main chain or any branch chain; and the catalyst is dibutyltin dilaurate.

[0028] In a preferred embodiment, the carbon chain R1 in the carboxyl-containing acrylate is a straight chain with 1-20 carbon atoms, or contains branches, and its function is only to connect the left and right functional groups. The choice can be made depending on the availability of raw materials or the difficulty of preparation. Taking the grafting of carboxyethyl methacrylate onto polyethyleneimine as an example, the preparation method is as follows: 1) Functionalization of polyethyleneimine:

[0029] 2) Silver ion complexation:

[0030] 3) Silver-functionalized polyethyleneimine grafted onto polyurethane acrylate

[0031] In another embodiment of the present invention, an internally antibacterial photocurable resin is proposed, comprising, by weight, 15-25 parts of silver-grafted modified polyurethane acrylate oligomer of Formula I, 45-60 parts of unmodified polyurethane acrylate oligomer, 20-30 parts of reactive diluent, 1.5-2.5 parts of photoinitiator, and 0.5-1.0 parts of co-initiator, obtained by stirring at 50-65°C in the dark for at least 30 minutes. This internally antibacterial photocurable resin is then used to prepare a surgical guide plate after photocuring via 3D printing. The surgical guide plate possesses intrinsic antibacterial function due to the presence of nano-silver fixed by chemical bonds within its material. Its antibacterial rate against Staphylococcus aureus and Escherichia coli is greater than 99.9%, and even after soaking in phosphate buffer for 30 days, the antibacterial rate against Staphylococcus aureus and Escherichia coli remains greater than 99.7%.

[0032] In the above embodiments, the rigid polyethyleneimine-silver complex in the internal antibacterial photocurable resin serves as a reinforcing phase, uniformly dispersed within the flexible polyurethane acrylate network through chemical bonds, forming a microscopic composite reinforcing structure. This significantly improves the tensile modulus and flexural strength of the material. Specifically, the tensile strength reaches 44.8-45.8 MPa, the elongation at break reaches 8.3-8.9%, and the flexural strength reaches 85.8-87.1 MPa. This allows the prepared surgical guide to better maintain shape stability during surgery, improving surgical precision.

[0033] In the above embodiments, the photocurable resin is used for 3D printing surgical guides. The uniformly distributed nano-silver inside the resin gives the material antibacterial properties. When the guide is drilled during surgery and internal debris is generated, the newly exposed surface still maintains its long-lasting antibacterial properties, effectively preventing the risk of deep tissue infection.

[0034] In a preferred embodiment, the aliphatic polyurethane acrylate can be obtained from manufacturers such as Sartomer (e.g., CN9021 series) and Allnex, preferably Sartomer CN9021NS; tripropylene glycol diacrylate (TPGDA) is purchased from Maclean's. The photoinitiator 2-isopropylthioxanthone (ITX) and the co-initiator methyldiethanolamine (MDEA) are both common raw materials, and were purchased from Maclean's in this experiment.

[0035] In a preferred embodiment, the above-mentioned photosensitive resin composition is poured into the resin tank of a DLP-type 3D printing device for printing. The printing parameters are a wavelength of 405nm, a light intensity of 80mW / cm², and a single-layer curing time of 8-12 seconds.

[0036] Example 1

[0037] (1) 50 mL of N,N-dimethylformamide, 10 mmol of polyethyleneimine, 12 mmol of carboxyethyl methacrylate, and a catalytic amount of p-toluenesulfonic acid were added to a reaction vessel. The grafting reaction was carried out at 80 °C for 6 hours under nitrogen protection. After the reaction was completed, the system was cooled to 25 °C, and 10 mL of an aqueous solution containing 1.5 mmol of silver nitrate was added under light-protected conditions. The mixture was stirred for another 4 hours to carry out the silver ion complexation reaction. The reaction solution was then added dropwise to 500 mL of diethyl ether to precipitate the precipitate. The precipitate was separated by filtration and vacuum drying to obtain a silver-loaded polyethyleneimine complex with terminal double bonds.

[0038] (2) Add 15g of the silver-loaded polyethyleneimine complex obtained in step (1), 100g of hydroxyl-terminated polyurethane acrylate oligomer and a catalytic amount of dibutyltin dilaurate to the reaction vessel, and carry out a melt polycondensation reaction at 85°C for 3 hours to obtain the silver-loaded grafted modified polyurethane acrylate oligomer.

[0039] (3) Add 20g of the silver-grafted modified polyurethane acrylate oligomer obtained in step (2), 50g of the unmodified polyurethane acrylate oligomer, 28g of tripropylene glycol diacrylate, 1.5g of 2-isopropylthioxanthone and 0.7g of methyl diethanolamine to the stirred tank in sequence, and stir at 55°C in the dark for 2 hours until a homogeneous transparent liquid is formed, thus obtaining the internal antibacterial light-curing resin.

[0040] Example 2

[0041] (1) 50 mL of N-methylpyrrolidone, 10 mmol of polyethyleneimine (molecular weight 2000), 10 mmol of carboxyethyl methacrylate, and a catalytic amount of p-toluenesulfonic acid were added to a reaction vessel. The grafting reaction was carried out at 75 °C for 7 hours under nitrogen protection. After the reaction was completed, the system was cooled to 25 °C, and 10 mL of an aqueous solution containing 1.0 mmol of silver nitrate was added under light-protected conditions. The mixture was stirred for another 5 hours to carry out the silver ion complexation reaction. The reaction solution was then added dropwise to 500 mL of acetone to precipitate the mixture. The precipitate was separated by filtration and vacuum drying to obtain a silver-loaded polyethyleneimine complex with terminal double bonds.

[0042] (2) Add 18g of the silver-loaded polyethyleneimine complex obtained in step (1), 100g of hydroxyl-terminated polyurethane acrylate oligomer and a catalytic amount of dibutyltin dilaurate to the reaction vessel, and carry out a melt polycondensation reaction at 80°C for 3.5 hours to obtain silver-loaded grafted modified polyurethane acrylate oligomer.

[0043] (3) Add 18g of the silver-grafted modified polyurethane acrylate oligomer obtained in step (2), 52g of unmodified polyurethane acrylate oligomer, 28g of tripropylene glycol diacrylate, 1.8g of 2-isopropylthioxanthone and 0.6g of methyl diethanolamine to the stirred tank in sequence, and stir at 60°C in the dark for 2 hours until a homogeneous transparent liquid is formed, thus obtaining the internal antibacterial light-curing resin.

[0044] Example 3

[0045] (1) Add 50 mL of dimethyl sulfoxide, 10 mmol of polyethyleneimine (molecular weight 1500), 15 mmol of carboxyethyl methacrylate, and a catalytic amount of p-toluenesulfonic acid to a reaction vessel. Under nitrogen protection, carry out the grafting reaction at 85 °C for 5 hours. After the reaction is completed, cool the system to 25 °C, add 10 mL of an aqueous solution containing 2.0 mmol of silver nitrate under light-protected conditions, and continue stirring to carry out the silver ion complexation reaction for 3 hours. Then, precipitate the reaction solution by adding it dropwise to 500 mL of n-hexane, filter and separate, and vacuum dry to obtain a silver-loaded polyethyleneimine complex with terminal double bonds.

[0046] (2) Add 22g of the silver-loaded polyethyleneimine complex obtained in step (1), 100g of hydroxyl-terminated polyurethane acrylate oligomer and a catalytic amount of dibutyltin dilaurate to the reaction vessel, and carry out a melt polycondensation reaction at 90°C for 2.5 hours to obtain silver-loaded grafted modified polyurethane acrylate oligomer.

[0047] (3) Add 22g of the silver-grafted modified polyurethane acrylate oligomer obtained in step (2), 48g of unmodified polyurethane acrylate oligomer, 28g of tripropylene glycol diacrylate, 2.0g of 2-isopropylthioxanthone and 0.8g of methyl diethanolamine to the stirred tank in sequence, and stir at 50°C in the dark for 2 hours until a homogeneous transparent liquid is formed, thus obtaining the internal antibacterial light-curing resin.

[0048] Comparative Example 1

[0049] Without adding silver-grafted modified polyurethane acrylate oligomer, 70g of unmodified polyurethane acrylate oligomer was directly mixed with 28g of tripropylene glycol diacrylate, 1.5g of 2-isopropylthioxanthone and 0.7g of methyldiethanolamine, and stirred at 55°C in the dark for 2 hours until a homogeneous transparent liquid was formed, thus obtaining a common light-curing resin.

[0050] Comparative Example 2

[0051] Silver-free grafted modified polyurethane acrylate oligomers were prepared according to the method of Example 1, i.e., silver nitrate was not added in step (1), and the remaining steps were exactly the same as in Example 1.

[0052] Comparative Example 3

[0053] The silver-loaded polyethyleneimine complex was prepared according to the method of Example 1, but in step (2), the grafting reaction was not carried out, and the silver-loaded polyethyleneimine complex was directly added to the resin system by physical blending.

[0054] Test case

[0055] 1. Compatibility testing

[0056] After testing, the photocurable resins of Examples 1, 2, and 3 were found to be transparent and uniform, with no phase separation. This is because the silver-loaded polyethyleneimine complex was chemically grafted onto the polyurethane acrylate backbone, enhancing its compatibility with the resin system.

[0057] In Comparative Example 2, the silver-free grafted modified polyurethane acrylate oligomer was also chemically bonded into the resin system, resulting in a transparent and uniform resin.

[0058] In Comparative Example 3, the silver-loaded polyethyleneimine complex was added through physical blending. Due to the difference in polarity between the polyethyleneimine segments and the resin matrix, the resin became slightly cloudy, indicating poor compatibility.

[0059] 2. Mechanical property testing of the parts

[0060] The photocurable resin was poured into the resin tank of the DLP 3D printer for printing. The printing parameters were a wavelength of 405 nm, a light intensity of 80 mW / cm², and a single-layer curing time of 8-12 seconds. Tensile properties and flexural strength were tested according to GB / T 2567-2021. The mechanical property test results are shown in Table 1 below.

[0061] Table 1: Mechanical property data of examples and comparative examples

[0062] As can be seen from the results in Table 1 above, in Examples 1, 2, and 3, silver-loaded grafted modified polyurethane acrylate oligomers were added to the photocurable resin. The rigid polyethyleneimine segments were uniformly dispersed in the flexible polyurethane acrylate network through chemical bonds, forming a micro-composite reinforced structure, which significantly improved the mechanical properties of the material. The tensile strength reached 44.8-45.8 MPa, the elongation at break reached 8.3-8.9%, and the flexural strength reached 85.8-87.1 MPa, which were significantly higher than those of the ordinary photocurable resin in Comparative Example 1.

[0063] In Comparative Example 2, a silver-free grafted modified polyurethane acrylate oligomer was added to the resin. Its rigid polyethyleneimine segments also played a reinforcing role, and the mechanical properties were comparable to those in the example.

[0064] The silver-loaded polyethyleneimine complex in Comparative Example 3 was added through physical blending. It had poor compatibility with the resin matrix and could not form an effective reinforcing network. The toughening and reinforcing effects were limited, and the mechanical properties were significantly lower than those in Example 1.

[0065] 3. Antibacterial performance test of the parts

[0066] A 50mm × 50mm × 1mm film sample was fabricated from photocurable resin using a DLP 3D printer. According to GB / T 31402-2015 "Test Method for Antimicrobial Properties of Plastic Surfaces", *Escherichia coli* (ATCC 25922) and *Staphylococcus aureus* (ATCC 6538) were used as test strains for the experiment. The simplified procedure is as follows: After sterilizing the sample surface, 0.2 mL of a (1.0~5.0) × 10⁻¹ solution was added. A bacterial suspension of CFU / mL was covered with a sterile film and incubated for 24 h at (37±1)℃ and relative humidity greater than 90%. Viable bacteria on the sample and blank control (same material without antibacterial components) were washed off with neutralization solution and cultured and counted to calculate the antibacterial rate.

[0067] Meanwhile, to visually compare the stability of the antibacterial components, the above-mentioned film samples were immersed in phosphate-buffered saline (PBS) at 37°C for 30 days. After drying, the antibacterial rate after immersion was tested using the same method described above to evaluate the durability of the antibacterial performance. The test results are shown in Table 2.

[0068] Table 2: Antibacterial Performance Test Results of Examples and Comparative Examples

[0069] As can be clearly seen from the results in Table 2 above, the photocurable resins prepared in Examples 1-3 all exhibited an initial antibacterial rate of up to 99.9% against Escherichia coli and Staphylococcus aureus, demonstrating extremely strong immediate antibacterial ability. Even after 30 days of PBS immersion, the antibacterial rate remained above 99.7%, fully demonstrating its long-lasting antibacterial performance. This is because the silver ions in the silver-grafted modified polyurethane acrylate oligomer are firmly chemically bonded to the polymer network and are in situ reduced to stable, uniformly distributed nano-silver during photocuring, achieving continuous and slow ion release, thus ensuring the durability of the antibacterial effect.

[0070] The antibacterial rates of Comparative Example 1 (without any functional components) and Comparative Example 2 (with silver-free grafted polymer) were both 0, confirming that the base resin itself does not have antibacterial properties and that the antibacterial function is entirely derived from the silver component.

[0071] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A silver-grafted modified polyurethane acrylate oligomer, characterized in that, It has the general structural formula shown in Equation I: ； R1 represents a carbon chain, and PUA represents polyurethane acrylate.

2. The method for preparing the silver-grafted modified polyurethane acrylate oligomer according to claim 1, characterized in that the step... include: S1. Polyethyleneimine and a carboxyl-containing acrylate undergo a condensation reaction under polar aprotic solvent and catalyst conditions to obtain polyethyleneimine containing double bonds; the structural formula of the carboxyl-containing acrylate is: R1 is a carbon chain; Under light-protected conditions, silver nitrate was added to the reaction solution to carry out a complexation reaction, and silver-loaded polyethyleneimine complex was obtained by precipitation. S2. The silver-loaded polyethyleneimine complex obtained in step S1 is reacted with the hydroxyl-containing polyurethane acrylate oligomer by melt polycondensation under the action of catalyst two to obtain the silver-loaded grafted modified polyurethane acrylate oligomer.

3. The preparation method according to claim 2, characterized in that, In step S1, the polar aprotic solvent is selected from at least one of N,N-dimethylformamide, N-methylpyrrolidone, or dimethyl sulfoxide; the non-solvent is at least one of diethyl ether, acetone, or n-hexane. And / or, the catalyst one is p-toluenesulfonic acid; And / or, the molar ratio of the polyethyleneimine to the carboxyl-containing acrylate is 1:(0.8-1.2). And / or, the reaction process is carried out under a protective atmosphere, at a reaction temperature of 70-85°C, for 4-8 hours.

4. The preparation method according to claim 2, characterized in that, In step S1, the molar ratio of silver nitrate to polyethyleneimine is (0.05-0.15):1; And / or, the complexation reaction is carried out at a temperature of 20-30°C for 3-5 hours; And / or, the precipitation process is carried out in a non-solvent environment.

5. The preparation method according to claim 2, characterized in that, In step S2, the mass ratio of the silver-loaded polyethyleneimine complex to the hydroxyl-containing polyurethane acrylate oligomer is (15-25):

100. And / or, the catalyst two is dibutyltin dilaurate.

6. An antibacterial 3D printing resin composition, characterized in that, The product comprises, by weight, 15-25 parts of silver-grafted modified polyurethane acrylate oligomer, 45-60 parts of unmodified polyurethane acrylate oligomer, 20-30 parts of reactive diluent, 1.5-2.5 parts of photoinitiator, and 0.5-1.0 parts of co-initiator; wherein the silver-grafted modified polyurethane acrylate oligomer is the silver-grafted modified polyurethane acrylate oligomer of claim 1 or the silver-grafted modified polyurethane acrylate oligomer prepared by the preparation method of claims 2-5.

7. The resin composition according to claim 6, characterized in that, The photoinitiator is at least one of benzophenone, 2-isopropylthioxanthone, and their derivatives. And / or, the co-initiator is methyldiethanolamine.

8. A method for preparing the resin composition according to claim 6 or 7, characterized in that, Take each component by weight and stir at 50-65℃ in the dark for at least 30 minutes to obtain the final product.

9. A 3D printed part, obtained by photocuring the resin composition of claim 6 or 7, or the resin composition obtained by the preparation method of claim 8, through 3D printing.

10. A surgical guide, characterized in that, The resin composition of claim 6 or 7, or the resin composition obtained by the preparation method of claim 8, is obtained by 3D printing and photocuring, or is obtained by 3D printing of the part as described in claim 9.

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