Antibacterial waterproof polyurethane elastomer for post-fracture fixation and preparation method and application thereof

Abstract

The present application belongs to the technical field of polyurethane elastomer, and particularly relates to an antibacterial and waterproof polyurethane elastomer for post-fracture fixation as well as a preparation method and application thereof. The antibacterial and waterproof polyurethane elastomer is composed of component A and component B. The component A is hydrophobic modified polyether polyol, polysiloxane, antioxidant and catalyst. The component B is guanidine salt antibacterial agent modified isophorone diisocyanate and aliphatic or alicyclic diisocyanate. The polyurethane elastomer obtained after curing of the component A and the component B is free of precipitation of antibacterial agent, has good antibacterial effect, good waterproof effect, good aging resistance and good weather resistance. The preparation method is scientific and reasonable, the viscosity of the component A and the component B is small, and the method is easy to operate. In the production, there is no risk such as explosive polymerization.

Description

Technical Field

[0001] This invention belongs to the field of polyurethane elastomer technology, specifically relating to antibacterial and waterproof polyurethane elastomers for fracture fixation, their preparation methods, and applications. Background Technology

[0002] Traditionally, plaster casts and splints are used to immobilize fractures, but these materials have several drawbacks. First, they have poor breathability, which can easily cause itching at the fracture site; sweating can also produce odors and increase the risk of bacterial growth and skin infections. Second, traditional plaster casts and splints are not waterproof, which greatly inconveniences patients when bathing in the summer.

[0003] Generally, antibacterial polyurethane elastomers achieve their antibacterial effect by adding antibacterial agents. For example, patent CN117447674A prepared a polyurethane elastomer composition and polyurethane elastomer, achieving an antibacterial effect by adding silver ions; patent CN118515847A prepared an antibacterial, waterproof, and breathable TPU for producing adhesive bandages, achieving an antibacterial effect by adding a ternary composite antibacterial material of graphene oxide-titanium dioxide-nano silver. However, the above technical solutions all impart antibacterial function to materials through physical blending, which easily leads to the migration, dissolution, and loss of antibacterial agents, making the antibacterial effect difficult to sustain, and the dissolved substances pose risks of skin irritation, allergies, and biosafety. Reactive antibacterial agents contain active groups in their molecular structure that can participate in polymerization or cross-linking. They can be firmly bonded to the substrate through chemical bonds without migration or precipitation. They have advantages such as long-lasting and stable antibacterial effect, high safety, and minimal impact on the mechanical properties of the substrate. They achieve efficient antibacterial and bactericidal effects through contact without releasing antibacterial components, making them more suitable for fields with stringent safety and durability requirements, such as skin contact, medical protection, and external fixation of fractures.

[0004] During fracture rehabilitation, patients inevitably need to wash and bathe daily, making the waterproof performance of medical fracture braces extremely important. A brace with excellent waterproofing can effectively prevent moisture from seeping into the fixation area, preventing skin maceration, itching, odor, and the proliferation of microorganisms caused by dampness. This reduces the risk of skin allergies, eczema, inflammation, and even wound infection, improving the patient's hygiene and comfort during wear. This positively impacts the overall rehabilitation experience and shortens the rehabilitation period.

[0005] Therefore, it is necessary to conduct further research on polyurethane elastomer materials and develop a polyurethane elastomer that does not allow antibacterial agents to migrate or dissolve, while also being waterproof and resistant to aging, so that it can be better applied to the fixation of fracture sites. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide an antibacterial and waterproof polyurethane elastomer for fracture fixation. During use, the antibacterial agent in the polyurethane elastomer does not migrate or leach out, exhibiting a long-lasting and stable antibacterial effect, high safety, good waterproofing, and aging resistance.

[0007] The present invention also provides a preparation method that is simple, easy to implement, and suitable for large-scale production.

[0008] The present invention also provides its application in the preparation of external fixation devices for fractures.

[0009] The antibacterial and waterproof polyurethane elastomer for fracture fixation described in this invention is composed of component A and component B in a mass ratio of 100:(30-45), wherein component A is composed of the following raw materials in parts by mass: Hydrophobically modified polyether polyol: 30~70 parts; Polysiloxane: 30-69 parts; Antioxidant: 0.9~1.5 parts; Catalyst: 0.3~0.5 parts; Component B is an isocyanate-terminated polyurethane prepolymer, composed of the following parts by weight of raw materials: Modified isocyanate 1: 15-30 parts; Diisocyanate 2: 70-85 parts; The modified isocyanate 1 is isophorone diisocyanate modified with guanidine salt antibacterial agents; The diisocyanate 2 is an aliphatic or alicyclic diisocyanate.

[0010] The hydrophobically modified polyether polyol is prepared by using pentaerythritol as an initiator and ethylene oxide as a chain extender to obtain a polyether polyol with a functionality of 4 and a number average molecular weight of 600-1100 g / mol, and then modified with a hydrophobic agent.

[0011] The hydrophobic agent is an alkyl acyl chloride with the molecular formula CH3-(CH2). n -CO-Cl, with a total number of carbon atoms of 14~18. Specifically, one or a mixture of several of tetradecyl chloride, hexadecyl chloride, and stearoyl chloride are selected.

[0012] The preparation of the hydrophobically modified polyether polyol includes the following steps: Dissolve the polyether polyol in tetrahydrofuran, add an acid-binding agent, heat to 60-70℃, and add alkyl acyl chloride dropwise while stirring under constant temperature conditions. Maintain the reaction temperature at 60-70℃ and continue the reaction at a constant temperature. Filter to remove hydrochloride, wash the residue, and dry to obtain the hydrophobically modified polyether polyol.

[0013] The polysiloxane is a hydroxyl-terminated polydimethylsiloxane with a number-average molecular weight of 600-1200 g / mol.

[0014] The antioxidant is one or more of UV-292, UV-1, and antioxidant 1076.

[0015] The catalyst is one or more of CUCAT-E01, CUCAT-E02, and CUCAT-E05.

[0016] The modified isocyanate 1 is polyhexamethylene guanidine hydrochloride (PHMG) modified isophorone diisocyanate (IPDI).

[0017] The preparation of the modified isocyanate 1 includes the following steps: IPDI was weighed into a reaction vessel, a catalyst was added, N2 was introduced, the mixture was heated and stirred, PHMG with a degree of polymerization of 3 was added, the reaction was continued to be heated, and the product was washed with solvent to obtain monofunctional polyhexamethylene guanidine hydrochloride modified isophorone diisocyanate (PHMG-IPDI).

[0018] The polyhexamethylene guanidine hydrochloride modified isophorone diisocyanate has an -NCO content of 5.5 wt.%.

[0019] The diisocyanate 2 is one or more of IPDI, HMDI, and HDI.

[0020] The method for preparing the antibacterial and waterproof polyurethane elastomer for fracture fixation according to the present invention includes the following steps: (1) Preparation of component A: Add hydrophobically modified polyether polyol, polysiloxane, antioxidant, and catalyst into a reaction vessel, stir evenly, protect with nitrogen, heat to 95-100℃, dehydrate under vacuum until the moisture content is <0.05wt.%, cool down and seal for storage to obtain component A. (2) Preparation of component B: Add modified isocyanate 1 and diisocyanate 2 to the reaction vessel, heat to 60-70℃, stir evenly under nitrogen protection, degas under vacuum, and cool down to obtain component B. (3) Mix components A and B evenly, pour into a mold to solidify and shape, and vulcanize at room temperature after opening the mold to obtain the product.

[0021] When mixing components A and B evenly, the mixing temperature should be maintained at 25-35℃. When pouring into molds of different shapes for curing, the working time is 20-30 minutes, and the mold opening time is 60-120 minutes.

[0022] Polyhexamethylene guanidine hydrochloride (PHMG) is a broad-spectrum, highly effective, and long-lasting antibacterial, bactericidal, and disinfectant agent that exhibits excellent killing and inhibitory effects against bacteria (including drug-resistant bacteria), viruses, and fungi. Unlike small-molecule quaternary ammonium salts and small-molecule guanidines, this substance also has advantages such as easy storage and low toxicity.

[0023] The two isocyanate groups in the isophorone diisocyanate (IPDI) molecule exhibit significantly different reactivity: due to the steric hindrance effect of the primary -NCO group on the cyclohexane ring and the α-substituted methyl group, the secondary -NCO group is more reactive. IPDI can achieve bonding with PHMG by reacting the -NCO group with the amino group in the PHMG molecule to form a carbamate bond.

[0024] The low surface energy of the long alkyl chain is used to hydrophobically modify the polyether polyol molecular chain in component A. Combined with low surface tension terminal hydroxyl polydimethylsiloxane, the unreacted isocyanate groups in IPDI can serve as subsequent reaction sites to react with the hydroxyl groups in component A. The long alkyl chain, silane segment and polyhexamethylene guanidine hydrochloride (PHMG) are grafted onto the polyurethane elastomer molecular chain segment by means of the bridging effect of IPDI, and finally a long-lasting antibacterial, bactericidal and waterproof polyurethane elastomer for fracture fixation is obtained.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows: 1) In this invention, polyhexamethylene guanidine hydrochloride (PHMG) is grafted onto the polyurethane elastomer molecular chain segment through the bridging effect of IPDI in component B. Compared with products with added antibacterial agents, the reactive antibacterial agent is firmly bound to the elastomer molecular chain through chemical bonds, and will not migrate or precipitate. It has the advantages of long-lasting and stable antibacterial effect and high safety.

[0026] 2) In this invention, the activity of isophorone diisocyanate in component B is greatly reduced after modification with PHMG. The hydrophobically modified polyether polyol in component A is a high-functionality, EO chain-extended polyether polyol, which has higher reactivity than conventional PO chain-extended polyether polyol. However, since EO is more hydrophilic than PO, long-chain alkyl acyl chloride is used for modification, introducing long alkyl chains into the polyurethane elastomer molecular chain. Combined with low surface tension terminal hydroxyl polydimethylsiloxane, its surface energy is greatly reduced, and the waterproof effect of polyurethane elastomer is improved.

[0027] 3) The preparation method of the antibacterial and waterproof polyurethane elastomer composite material for fracture fixation of the present invention has a simple process flow, low viscosity and good fluidity of each component, long working time, convenient manual casting, and no risk of explosive polymerization during production. Detailed Implementation

[0028] The present invention will be further described below with reference to the embodiments.

[0029] Unless otherwise specified, all raw materials used in the examples were commercially available.

[0030] The raw materials used in the examples and comparative examples are described below: Preparation of polyether polyols using pentaerythritol as an initiator and ethylene oxide as a chain extender: A stainless steel high-pressure reactor was sealed and purged five times with high-purity nitrogen to ensure the oxygen content inside was below 0.1%. Pentaerythritol and KOH catalyst were added to the reactor, stirring was started, and the temperature was raised to 110±10℃. Vacuum dehydration was performed for 1.5 hours under a vacuum of ≥-0.095MPa to remove free water and water of crystallization, controlling the moisture content to ≤0.01% to avoid side reactions caused by moisture leading to a lower molecular weight. After dehydration was complete and pentaerythritol was fully melted and dispersed, the temperature was stabilized at 120±5℃, and ethylene oxide was slowly and continuously introduced. The reaction pressure was controlled at 0.2~0.4MPa, and the EO feed rate was strictly controlled to maintain stable temperature and pressure and prevent violent exothermic polymerization. After the total amount of ethylene oxide required for the designed molecular weight was added, the reaction was maintained at this temperature for 3 hours. After the reaction, phosphoric acid and adsorbent were added for neutralization and adsorption. The product was obtained after dehydration and filtration.

[0031] Specifically: The reaction of pentaerythritol and ethylene oxide in a molar ratio of 1:3 yielded PEREO-664, a polyether polyol with a number average molecular weight of 664 g / mol. The reaction of pentaerythritol and ethylene oxide in a molar ratio of 1:4 yielded PEREO-840, a polyether polyol with a number average molecular weight of 840 g / mol. The reaction of pentaerythritol and ethylene oxide in a molar ratio of 1:5 yielded PEREO-1017, a polyether polyol with a number average molecular weight of 1017 g / mol.

[0032] HTPDMS-600: Hydroxyl-terminated polydimethylsiloxane, functionality 2, number-average molecular weight 600 g / mol, Shanghai Maclean Biochemical Technology Co., Ltd. HTPDMS-800: Hydroxyl-terminated polydimethylsiloxane, functionality 2, number-average molecular weight 800 g / mol, Shanghai Maclean Biochemical Technology Co., Ltd. HTPDMS-1000: Hydroxyl-terminated polydimethylsiloxane, functionality 2, number-average molecular weight 1000 g / mol, Shanghai Maclean Biochemical Technology Co., Ltd. HTPDMS-1200: Hydroxyl-terminated polydimethylsiloxane, functionality 2, number-average molecular weight 1200 g / mol, Shanghai Maclean Biochemical Technology Co., Ltd. C310: Polyether polyol, glycerol as initiator, PO chain extender, functionality 3, number average molecular weight 1000, Shandong Yinuowei New Materials Co., Ltd. C210, polyether polyol, ethylene glycol as initiator, PO chain extender, functionality 2, number average molecular weight 1000, Shandong Yinuowei New Materials Co., Ltd. Alkyl chlorides; n-Tetradecanoyl chloride, n-Hexadecanoyl chloride, n-Octadecanoyl chloride, Huzhou Shalong Chemical Co., Ltd.; Polyhexamethylene guanidine hydrochloride, Shanghai Maclean Biochemical Technology Co., Ltd.; HMDI: 4,4-Dicyclohexylmethane diisocyanate, Wanhua Chemical Group Co., Ltd. IPDI: Isophorone diisocyanate, Wanhua Chemical Group Co., Ltd. MDI-50: Diphenylmethane diisocyanate, Wanhua Chemical Group Co., Ltd.; CDMDI-100L: Carbodiimide-modified diphenylmethane diisocyanate, Wanhua Chemical Group Co., Ltd.; UV-292, UV-1, Antioxidant 1076: BASF (China) Co., Ltd. CUCAT-E01, CUCAT-E02, CUCAT-E05: Composite catalysts, Guangzhou Yourun Synthetic Materials Co., Ltd.

[0033] Preparation of hydrophobically modified polyether polyols: 1. Preparation of tetradecyl chloride-modified polyether polyol PEREO-664-14 Dissolve PEREO-664 polyether polyol with a moisture content of less than 0.05% in tetrahydrofuran, add triethylamine as an acid binder (the molar ratio of triethylamine to acyl chloride is 1.05:1), heat to 60℃, and add tetradecyl acyl chloride dropwise while stirring under constant temperature conditions. The addition is completed within 1 hour. The molar ratio of polyether polyol to alkyl acyl chloride is 1:1. Maintain the reaction temperature at 60±2℃ and react at a constant temperature for 5 hours. Filter to remove triethylamine hydrochloride, wash the residue with ethanol first, then with deionized water, and dry to obtain hydrophobically modified polyether polyol PEREO-664-14.

[0034] 2. Preparation of hexadecyl chloride-modified polyether polyol PEREO-840-16 Dissolve PEREO-840 polyether polyol with a moisture content of less than 0.05% in tetrahydrofuran, add triethylamine as an acid binder (the molar ratio of triethylamine to acyl chloride is 1.05:1), heat to 65℃, and add hexadecyl acyl chloride dropwise while stirring under constant temperature conditions. The addition is completed within 1 hour. The molar ratio of polyether polyol to alkyl acyl chloride is 1:1. Maintain the reaction temperature at 65±2℃ and react at a constant temperature for 6 hours. Filter to remove triethylamine hydrochloride, wash the residue with ethanol first, then with deionized water, and dry to obtain hydrophobically modified polyether polyol PEREO-840-16.

[0035] 3. Preparation of PEREO-1017-18, a polyether polyol modified with octadecyl chloride. Dissolve PEREO-1017 polyether polyol with a moisture content of less than 0.05% in tetrahydrofuran, add triethylamine as an acid binder (the molar ratio of triethylamine to acyl chloride is 1.05:1), heat to 70℃, and add octadecyl acyl chloride dropwise while stirring under constant temperature conditions. The addition is completed within 1 hour. The molar ratio of polyether polyol to alkyl acyl chloride is 1:1. Maintain the reaction temperature at 70±2℃ and react at a constant temperature for 6 hours. Filter to remove triethylamine hydrochloride, wash the residue with ethanol first, then with deionized water, and dry to obtain hydrophobically modified polyether polyol PEREO-1017-18.

[0036] The preparation of modified isocyanate 1 includes the following steps: A measured amount of IPDI was weighed into a three-necked flask, and 1% (by mass) of dibutyltin dilaurate catalyst was added to all raw materials. N2 was introduced, and the temperature was set to 60℃. The mixture was stirred for 5 min. A measured amount of PHMG with a degree of polymerization of 3 was added, and the molar ratio of IPDI to PHMG was set to 1:1. The reaction temperature was set to 110-120℃ and the reaction was carried out for 2 h. After the reaction, the product was washed three times with toluene to obtain monofunctional PHMG-IPDI with -NCO = 5.5 wt.%.

[0037] Example 1 The method for preparing the antibacterial and waterproof polyurethane elastomer for fracture fixation includes the following steps: (1) Preparation of component A: By weight, 30 parts of hydrophobic modified polyether polyol PEREO-664-14, 68.8 parts of hydroxyl-terminated polydimethylsiloxane HTPDMS-1000, 0.3 parts of catalyst CUCAT-E01, 0.3 parts of antioxidant UV-292, 0.3 parts of UV-1, and 0.3 parts of antioxidant 1076 were added to a three-necked flask and mixed. The mixture was heated to 95°C and vacuumed to -0.095 MPa to dehydrate until the moisture content was less than 0.05 wt.%, thus obtaining component A. (2) Preparation of component B: Add 15 parts PHMG-IPDI and 85 parts IPDI to a three-necked flask, set the temperature to 60℃, stir evenly under nitrogen protection, degas under vacuum, cool and seal for storage, and obtain component B with an isocyanate content of 32.2 wt.%. (3) Preparation of polyurethane elastomers for post-fracture fixation: When using, mix components A and B evenly at a mass ratio of A:B=100:31, at a mixing temperature of 30±5℃, pour into a mold, and allow for 20 minutes of operation and 60 minutes of mold opening. After curing at room temperature for 7 days, a polyurethane elastomer product for fracture fixation with a hardness of Shore D65 is obtained.

[0038] Example 2 The method for preparing the antibacterial and waterproof polyurethane elastomer for fracture fixation includes the following steps: (1) Preparation of component A: By weight, 50 parts of hydrophobic modified polyether polyol PEREO-840-16, 48.6 parts of hydroxyl-terminated polydimethylsiloxane HTPDMS-800, 0.5 parts of catalyst CUCAT-E01, 0.3 parts of antioxidant UV-292, 0.3 parts of UV-1, and 0.3 parts of antioxidant 1076 were added to a three-necked flask and mixed. The mixture was heated to 95°C and vacuumed to -0.095 MPa to dehydrate until the moisture content was less than 0.05 wt.%, thus obtaining component A. (2) Preparation of component B: By weight, 20 parts of PHMG-IPDI and 80 parts of IPDI were added to a three-necked flask, the temperature was set to 60°C, the mixture was stirred evenly under nitrogen protection, vacuum degassing was performed, and the mixture was cooled and sealed for storage to obtain component B with an isocyanate content of 30.3 wt.%. (3) Preparation of polyurethane elastomers for post-fracture fixation: When using, mix components A and B evenly at a mass ratio of A:B=100:37, at a mixing temperature of 30±5℃, pour into a mold, and allow for 22 minutes of operation and 60 minutes of mold opening. After curing at room temperature for 7 days, a polyurethane elastomer product for fracture fixation with a Shore D71 hardness is obtained.

[0039] Example 3 The method for preparing the antibacterial and waterproof polyurethane elastomer for fracture fixation includes the following steps: (1) Preparation of component A: By weight, 50 parts of hydrophobic modified polyether polyol PEREO-1017-18, 48 parts of hydroxyl-terminated polydimethylsiloxane HTPDMS-600, 0.5 parts of catalyst CUCAT-E05, 0.5 parts of antioxidant UV-292, 0.5 parts of UV-1, and 0.5 parts of antioxidant 1076 were added to a three-necked flask and mixed. The mixture was heated to 95°C and vacuumed to -0.095 MPa to dehydrate until the moisture content was less than 0.05 wt.%, thus obtaining component A. (2) Preparation of component B: By weight, 30 parts of PHMG-IPDI and 70 parts of IPDI were added to a three-necked flask, the temperature was set to 60°C, the mixture was stirred evenly under nitrogen protection, vacuum degassing was performed, and the mixture was cooled and sealed for storage to obtain component B with an isocyanate content of 27.5 wt.%. (3) Preparation of polyurethane elastomers for post-fracture fixation: When using, mix components A and B evenly at a mass ratio of A:B=100:43, with a mixing temperature of 30±5℃, pour into a mold, and allow for 30 minutes of operation and 120 minutes of mold opening. After curing at room temperature for 7 days, a polyurethane elastomer product for fracture fixation with a hardness of Shore D68 is obtained.

[0040] Example 4 The method for preparing the antibacterial and waterproof polyurethane elastomer for fracture fixation includes the following steps: (1) Preparation of component A: By weight, 30 parts of hydrophobic modified polyether polyol PEREO-1017-18, 40 parts of hydrophobic modified polyether polyol PEREO-664-14, 30 parts of hydroxyl-terminated polydimethylsiloxane HTPDMS-800, 0.3 parts of catalyst CUCAT-E02, 0.5 parts of antioxidant UV-292, 0.5 parts of UV-1, and 0.5 parts of antioxidant 1076 were added to a three-necked flask and mixed. The mixture was heated to 95°C and vacuumed to -0.095 MPa to dehydrate until the moisture content was less than 0.05 wt.%, thus obtaining component A. (2) Preparation of component B: By weight, 20 parts of PHMG-IPDI and 80 parts of HMDI were added to a three-necked flask, the temperature was set to 60°C, and the mixture was stirred evenly under nitrogen protection. The mixture was then degassed under vacuum, cooled, sealed, and stored to obtain component B with an isocyanate content of 26.7 wt.%. (3) Preparation of polyurethane elastomers for post-fracture fixation: When using, mix components A and B evenly at a mass ratio of A:B=100:43, at a mixing temperature of 30±5℃, pour into a mold, and allow for 25 minutes of operation and 90 minutes of mold opening. After curing at room temperature for 7 days, a polyurethane elastomer product for fracture fixation with a Shore D of 73 is obtained.

[0041] Comparative Example 1 Based on Example 1, PHMG-IPDI in component B is replaced with IPDI, while component A remains unchanged. When using, components A and B are mixed evenly at a mass ratio of A:B=100:26 (R value is the same as in Example 1), the mixing temperature is 30±5℃, and the mixture is poured into a mold. The working time is 20 minutes, the mold opening time is 60 minutes, and after post-curing at room temperature for 7 days, a polyurethane elastomer product for fracture fixation with a Shore D hardness of 75 is obtained.

[0042] Comparative Example 2 Based on Example 2, PEREO-840-16 in component A was replaced with C310 by mass, while component B remained unchanged. When using, components A and B were mixed evenly at a mass ratio of A:B=100:38 (R value is the same as in Example 2), the mixing temperature was 30±5℃, and the mixture was poured into a mold. The working time was 20 minutes, the mold opening time was 60 minutes, and after post-curing at room temperature for 7 days, a polyurethane elastomer product for fracture fixation with a Shore D71 hardness was obtained.

[0043] Comparative Example 3 Based on Example 3, IPDI in component B was replaced with CDMDI-100L (alicyclic isocyanate was replaced with aromatic isocyanate). 70 parts of CDMDI-100L and 30 parts of PHMG-IPDI were added to a three-necked flask. The temperature was set to 60°C, and the mixture was stirred evenly under nitrogen protection. Vacuum degassing was performed, and the mixture was cooled and sealed for storage, resulting in component B with an isocyanate content of 22.2 wt.%. Component A remained unchanged. When using the mixture, components A and B were mixed evenly at a mass ratio of A:B=100:54 (R value consistent with Example 3) at a mixing temperature of 30±5°C. The mixture was poured into a mold, and the workable time was 20 minutes. After post-curing at room temperature for 7 days, a polyurethane elastomer product for fracture fixation with a Shore D hardness of 68 was obtained.

[0044] Comparative Example 4 The method for preparing the antibacterial and waterproof polyurethane elastomer for fracture fixation includes the following steps: (1) Preparation of component A: By mass, add 50 parts of polyether polyol C210, 48.8 parts of polyether polyol C310, 0.3 parts of catalyst CUCAT-E01, 0.3 parts of antioxidant UV-1 and 0.3 parts of antioxidant 1076 to a three-necked flask and mix. Heat to 95°C and vacuum to -0.095 MPa to dehydrate until the moisture content is less than 0.05 wt.%, thus obtaining component A; (2) Preparation of component B: By mass, add 50 parts of CDMDI-100L and 50 parts of MDI-50 to a three-necked flask, set the temperature to 60℃, stir evenly under nitrogen protection, degas under vacuum, cool and seal for storage, and obtain component B with an isocyanate content of 31.5wt.%. (3) Preparation of polyurethane elastomer for fracture fixation: When using, components A and B are mixed evenly at a mass ratio of A:B=100:34 (R value is the same as in Example 4), the mixing temperature is 30±5℃, and the mixture is poured into a mold. The working time is 20 minutes, the mold opening time is 60 minutes, and after curing at room temperature for 7 days, a polyurethane elastomer product for fracture fixation with a hardness of Shore D69 is obtained.

[0045] The products obtained from the examples and comparative examples were subjected to performance tests, and the test results are shown in Table 1 below: Table 1 Performance Test Results

[0046] Note: Hardness was tested according to GB / T 531.1-2008; tensile strength and elongation at break were tested according to GB / T 528-2009; water contact angle of the product was tested according to GB / T 30693-2014; phenol yellow was tested according to ISO105-X18:2007.

[0047] The inhibition rate of Staphylococcus aureus was tested using the method in GB / T 38483-2020. The calculation method was: inhibition rate (%) = [(diameter of blank group - diameter of experimental group) / diameter of blank group] × 100%.

[0048] As shown in Table 1, compared with Comparative Example 1, in Example 1, 15% PHMG-IPDI was added to component B to replace IPDI. The guanidine matrix of polyhexamethylene guanidine (PHMG) becomes positively charged after guanidine propionation, allowing it to electrostatically bind to the negatively charged bacterial cell wall, forming a polymer membrane. This structure blocks bacterial material exchange and metabolic processes, ultimately leading to bacterial apoptosis. Therefore, the antibacterial effect of Example 1 is significantly better than that of Comparative Example 1, which had the worst antibacterial rate.

[0049] Compared with Example 2, in Comparative Example 2, PEREO-840-16 in component A was replaced with C310. No long alkyl chain was used to modify it. However, because low surface energy terminal hydroxyl polydimethylsiloxane HTPDMS-800 was added, the elastomer prepared by it had a low water contact angle and poor waterproof effect.

[0050] Compared to Example 3, in Comparative Example 3, IPDI in component B was replaced with CDMDI-100L. Compared to the aliphatic isocyanate IPDI, the benzene ring structure of the aromatic isocyanate CDMDI-100L is more easily oxidized, resulting in polyurethane elastomers prepared from it that are more prone to aging, have poorer weather resistance, and shorter service life. However, because its component B contains 30% HPMG-IPDI, its phenolic yellow test grade ranks second to last, which is better than Comparative Example 4. Because it has the highest amount of PHMG-IPDI added, its antibacterial rate is similar to that of Example 3.

[0051] Compared with Examples 1-3, Comparative Example 4 replaced the hydrophobically modified polyether and hydroxyl-terminated polydimethylsiloxane with ordinary polyether polyols C210 and C310, and replaced components B PHMG-IPDI and IPDI with CDMDI-100L and MDI-50. It did not have polyhexamethylene guanidine (PHMG) for antibacterial modification, nor did it have hydrophobically modified polyether polyols and low surface energy hydroxyl-terminated polydimethylsiloxane. Therefore, its antibacterial effect, waterproof effect, and phenol yellow test results for aging resistance were the worst.

Claims

1. An antibacterial and waterproof polyurethane elastomer for post-fracture fixation, characterized in that, It is composed of component A and component B in a mass ratio of 100:(30-45), wherein component A is composed of the following raw materials in parts by mass: Hydrophobically modified polyether polyol: 30~70 parts; Polysiloxane: 30-69 parts; Antioxidant: 0.9~1.5 parts; Catalyst: 0.3~0.5 parts; Component B is an isocyanate-terminated polyurethane prepolymer, composed of the following parts by weight of raw materials: Modified isocyanate 1: 15-30 parts; Diisocyanate 2: 70-85 parts; The modified isocyanate 1 is isophorone diisocyanate modified with guanidine salt antibacterial agents; The diisocyanate 2 is an aliphatic or alicyclic diisocyanate.

2. The antibacterial and waterproof polyurethane elastomer for fracture fixation according to claim 1, characterized in that, The hydrophobically modified polyether polyol is prepared by using pentaerythritol as an initiator and ethylene oxide as a chain extender to obtain a polyether polyol with a functionality of 4 and a number average molecular weight of 600-1100 g / mol, and then modified with a hydrophobic agent.

3. The antibacterial and waterproof polyurethane elastomer for fracture fixation according to claim 2, characterized in that, The hydrophobic agent is an alkyl acyl chloride with the molecular formula CH3-(CH2). n -CO-Cl, with a total number of carbon atoms of 14~18.

4. The antibacterial and waterproof polyurethane elastomer for fracture fixation according to claim 1, characterized in that, The polysiloxane mentioned is a hydroxyl-terminated polydimethylsiloxane.

5. The antibacterial and waterproof polyurethane elastomer for fracture fixation according to claim 1, characterized in that, The antioxidant is one or more of UV-292, UV-1, and antioxidant 1076.

6. The antibacterial and waterproof polyurethane elastomer for fracture fixation according to claim 1, characterized in that, The catalyst is one or more of CUCAT-E01, CUCAT-E02, and CUCAT-E05.

7. The antibacterial and waterproof polyurethane elastomer for fracture fixation according to claim 1, characterized in that, The modified isocyanate 1 is a polyhexamethylene guanidine hydrochloride modified isophorone diisocyanate.

8. The antibacterial and waterproof polyurethane elastomer for fracture fixation according to claim 1, characterized in that, The diisocyanate 2 is one or more of IPDI, HMDI, and HDI.

9. A method for preparing an antibacterial and waterproof polyurethane elastomer for fracture fixation according to any one of claims 1 to 8, characterized in that, Includes the following steps: (1) Preparation of component A: Add hydrophobically modified polyether polyol, polysiloxane, antioxidant, and catalyst into a reaction vessel, stir evenly, heat to dehydrate under vacuum, cool and seal for storage to obtain component A. (2) Preparation of component B: Modified isocyanate 1 and diisocyanate 2 are added to the reaction vessel, the temperature is raised and the reaction is carried out, the bubbles are removed under vacuum, and the temperature is lowered to obtain component B. (3) Mix components A and B evenly, pour into a mold to solidify and shape, and vulcanize at room temperature after opening the mold to obtain the product.

10. The application of an antibacterial and waterproof polyurethane elastomer for fracture fixation according to any one of claims 1 to 8, characterized in that, Used to prepare external fixation devices after fractures.

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