Bone screw baffle and preparation method thereof

Abstract

The present invention discloses a bone screw baffle and a preparation method thereof, and belongs to the technical field of medical devices. The bone screw baffle comprises the following raw materials in parts by weight: polylactic acid: 100-120 parts, hydroxyapatite: 50-60 parts, modified plasticizer: 6-10 parts, chain extender: 5-10 parts; the present invention prepares intermediate 1 by esterification reaction of decenyl succinic anhydride and (9Z, 12Z, 15Z)-9,12,15-octadecatriene-1-ol, and then performs epoxidation and acetylation ring-opening reaction on intermediate 1, and finally obtains modified plasticizer. The bone screw baffle prepared by the present invention has excellent bending strength.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to a bone screw baffle and a preparation method thereof. Background Art

[0002] In recent years, the increasing aging of the population, traffic accident injuries and other reasons have led to a continuous increase in the incidence of fractures, and its treatment often requires the use of bone screw baffles to fix bone screws. Polylactic acid (PLA) is a biodegradable polymer material with excellent biocompatibility and absorbability, which can be used in clinical bone repair. However, the bone screw baffles prepared by polylactic acid are brittle, have poor bending strength, and are easy to break, resulting in the failure of the entire bone fixation system. Therefore, reducing the inherent brittleness of polylactic acid and improving its bending strength have become the key points that need to be overcome urgently for the bone screw baffle of this material. Plasticizers can improve the flexibility and ductility of polylactic acid plastic products, optimize their mechanical properties, and thus improve the ability of the bone screw baffle of this material to protect soft tissues, thereby avoiding damage to soft tissues caused by the brittle fracture of the fixing baffle during surgery. The most widely used phthalate plasticizers on the market are dioctyl phthalate (DOP), but studies have shown that phthalate plasticizers are toxic to humans and animals, and their use has been restricted in many fields such as medical supplies and children's toys. Therefore, the development of low-toxic non-phthalate plasticizers is extremely critical to improving the bending strength of polylactic acid bone screw baffles. Summary of the invention

[0003] In view of the deficiencies in the prior art, an object of the present invention is to provide a bone screw baffle and a preparation method thereof.

[0004] To achieve the above object, the present invention is implemented through the following technical solutions:

[0005] A bone screw baffle comprises the following raw materials in parts by weight:

[0006] Polylactic acid: 100-120 parts,

[0007] Hydroxyapatite: 50-60 parts,

[0008] Modified plasticizer: 6-10 parts,

[0009] Chain extender: 5-10 parts;

[0010] The modified plasticizer is prepared by the following method:

[0011] S1: Under nitrogen protection, decenyl succinic anhydride and (9Z,12Z,15Z)-9,12,15-octadecatriene-1-ol were added to the reactor in sequence, stirred and mixed, heated to 140-150°C, kept warm for 10-20 minutes, then heated to 170-180°C, and then added with catalyst isopropyl titanate, kept warm for 10-15 minutes, and then heated to 210-230°C. After reacting for 3-5 hours, intermediate 1 was obtained, and its reaction equation is shown as follows:

[0012]

[0013] S2: DMF, intermediate 1, and strong acid cation exchange resin are added to the reactor in sequence, stirred, and heated to 50-70°C; then formic acid and H2O2 solution are mixed, and the mixed solution of formic acid and H2O2 solution is slowly added, and after reacting for 4-8 hours, intermediate 2 is obtained, and its reaction equation is shown as follows:

[0014]

[0015] S3: Tetrahydrofuran, intermediate 2, acetic anhydride, and strong acid cation exchange resin are added to the reactor in sequence, stirred, heated to 100-140°C, and reacted for 4-8 hours to obtain a modified plasticizer. The reaction equation is shown as follows:

[0016]

[0017] In step S1, the feed mass ratio of decenyl succinic anhydride, (9Z,12Z,15Z)-9,12,15-octadecatriene-1-ol, and catalyst isopropyl titanate is 22:(60-70):(0.03-0.05).

[0018] In step S2, the feed mass ratio of DMF, intermediate 1, strong acid cation exchange resin, formic acid, and H2O2 solution is 120:(34-38):(6-8):(14-18):(36-38).

[0019] In step S3, the feed mass ratio of tetrahydrofuran, intermediate 2, acetic anhydride, and strong acid cation exchange resin is 100:(32-38):(60-64):(3-5).

[0020] The hydroxyapatite is hydroxyapatite microspheres.

[0021] The chain extender is ADR-4368C.

[0022] A method for preparing a bone screw baffle comprises the following steps:

[0023] (1) Weigh by weight: polylactic acid: 100-120 parts, hydroxyapatite: 50-60 parts, modified plasticizer: 6-10 parts, chain extender: 5-10 parts;

[0024] (2) Adding polylactic acid, hydroxyapatite, modified plasticizer and chain extender into a high-speed blender in sequence, stirring at 100-140°C for 20-30 minutes, and then melt granulating through a twin-screw extruder at an extrusion temperature of 160-180°C and a screw speed of 75 r / min;

[0025] (3) feeding the extruded particles in step (2) into a 3D wire making machine to form wires with a diameter of 1.75±0.05 mm at an extrusion temperature of 170-190°C;

[0026] (4) The wire extruded in step (3) is fed into a fused deposition model 3D printer for printing to obtain a bone screw baffle; the nozzle temperature of the fused deposition model 3D printer is 170-190° C., the base plate temperature is 50-70° C., and the printing speed is 50-60 mm / s.

[0027] Due to the adoption of the above technical solution, the beneficial effects of the present invention include:

[0028] The invention prepares the intermediate 1 through the esterification reaction of decenyl succinic anhydride and (9Z, 12Z, 15Z)-9,12,15-octadecatriene-1-ol, and then performs epoxidation and acetylation ring-opening reaction on the intermediate 1 to finally obtain the modified plasticizer.

[0029] The modified plasticizer prepared by the present invention contains multiple ester groups. After being blended with polylactic acid, it can weaken the interaction between polylactic acid molecular chains, increase the mobility of polylactic acid molecular chains, improve the fluidity and softness of polylactic acid materials, thereby reducing the brittleness of polylactic acid bone screw baffles, improving the bending strength of polylactic acid bone screw baffles, and can bear a larger partial stress when subjected to force, thereby reducing the risk of bone screw loosening. DETAILED DESCRIPTION

[0030] The invention will be further described below in conjunction with the embodiments, but the invention is not limited to these embodiments.

[0031] Example 1 Preparation of modified plasticizer:

[0032] S1: Under nitrogen protection, 22 g of decenyl succinic anhydride and 60 g of (9Z, 12Z, 15Z)-9,12,15-octadecatriene-1-ol were added to the reactor in sequence, stirred and mixed, heated to 140°C, kept warm for 20 min, then heated to 170°C, and then 0.03 g of catalyst isopropyl titanate was added, kept warm for 15 min, and then heated to 210°C and reacted for 5 h. After the reaction was completed, the filtrate was filtered and transferred to a separatory funnel, allowed to stand for stratification, the water layer was removed, and then washed with 200 g of deionized water, and then dried with 200 g of anhydrous sodium sulfate for 2 h, distilled under reduced pressure at 60°C for 1 h, and vacuum dried at 50°C for 6 h to obtain intermediate 1;

[0033] S2: 120g DMF, 34g intermediate 1, and 6g strong acid cation exchange resin were added to the reactor in sequence, stirred, and heated to 50°C; then 14g formic acid and 36g H2O2 solution (30wt%) were mixed evenly, and the mixed solution of formic acid and H2O2 solution was slowly added, dripped for 10min, reacted for 8h, and after the reaction was completed, 200g deionized water was added for washing, and the mixture was distilled at 60°C under reduced pressure for 1h, and vacuum dried at 50°C for 5h to obtain intermediate 2;

[0034] S3: 100 g of tetrahydrofuran, 32 g of intermediate 2, 60 g of acetic anhydride and 3 g of strong acid cation exchange resin were added into the reactor in sequence, stirred, heated to 100°C, reacted for 8 h, and after the reaction, 200 g of deionized water was added for washing, distilled at 65°C under reduced pressure for 1 h, and vacuum dried at 50°C for 5 h to obtain a modified plasticizer.

[0035] Example 2 Preparation of modified plasticizer:

[0036] S1: Under nitrogen protection, 22 g of decenyl succinic anhydride and 65 g of (9Z, 12Z, 15Z)-9,12,15-octadecatriene-1-ol were added to the reactor in sequence, stirred and mixed, heated to 145°C, kept warm for 15 min, then heated to 175°C, and then 0.04 g of catalyst isopropyl titanate was added, kept warm for 13 min, and then heated to 220°C and reacted for 4 h. After the reaction was completed, the filtrate was filtered and transferred to a separatory funnel, allowed to stand and stratify, the water layer was removed, and then washed with 200 g of deionized water, and then dried with 200 g of anhydrous sodium sulfate for 2 h, distilled under reduced pressure at 60°C for 1.5 h, and dried under vacuum at 60°C for 5 h to obtain intermediate 1;

[0037] S2: 120g DMF, 36g intermediate 1, and 7g strong acid cation exchange resin were added to the reactor in sequence, stirred, and heated to 60°C; then 16g formic acid and 37g H2O2 solution (30wt%) were mixed, and the mixed solution of formic acid and H2O2 solution was slowly added, dripped for 13min, reacted for 6h, and after the reaction was completed, 200g deionized water was added for washing, and the mixture was distilled at 60°C under reduced pressure for 1.5h, and vacuum dried at 60°C for 4h to obtain intermediate 2;

[0038] S3: 100g of tetrahydrofuran, 36g of intermediate 2, 62g of acetic anhydride, and 4g of strong acid cation exchange resin were added to the reactor in sequence, stirred, heated to 120°C, reacted for 6h, and after the reaction, 200g of deionized water was added for washing, and the mixture was distilled at 65°C under reduced pressure for 1.5h, and vacuum dried at 60°C for 4h to obtain a modified plasticizer, the hydrogen nuclear magnetic resonance spectrum data of which are as follows: 1 H NMR (500 MHz, Chloroform-d) δ 5.24 – 4.98 (m, 14H), 4.21 – 3.98 (m, 4H), 3.40 (q, J = 9.5Hz, 1H), 2.96 – 2.86 (m, 1H), 2.69 – 2.58 (m, 1H), 2.34 (dtd, J = 15.2, 7.6,1.6 Hz, 4H), 2.14 (dt, J = 14.9, 7.5 Hz, 4H), 2.11 – 2.05 (m, 39H), 2.05 (s,3H), 1.94 – 1.88 (m, 1H), 1.86 – 1.76 (m, 4H), 1.72 – 1.50 (m, 7H), 1.50 –1.39 (m, 5H), 1.39 – 1.32 (m, 7H), 1.33 – 1.18 (m, 22H), 1.01 – 0.96 (m, 6H), 0.92 – 0.86 (m, 3H).

[0039] Example 3 Preparation of modified plasticizer:

[0040] S1: Under nitrogen protection, 22 g of decenyl succinic anhydride and 70 g of (9Z, 12Z, 15Z)-9,12,15-octadecatriene-1-ol were added to the reactor in sequence, stirred and mixed, heated to 150°C, kept warm for 10 min, then heated to 180°C, and then 0.05 g of catalyst isopropyl titanate was added, kept warm for 10 min, and then heated to 230°C and reacted for 3 h. After the reaction was completed, the filtrate was filtered and transferred to a separatory funnel, allowed to stand for stratification, the water layer was removed, and then washed with 200 g of deionized water, and then dried with 200 g of anhydrous sodium sulfate for 2 h, distilled under reduced pressure at 60°C for 1 h, and vacuum dried at 70°C for 4 h to obtain intermediate 1;

[0041] S2: 120g DMF, 38g intermediate 1, and 8g strong acid cation exchange resin were added to the reactor in sequence, stirred, and heated to 70°C; then 18g formic acid and 38g H2O2 solution (30wt%) were mixed evenly, and the mixed solution of formic acid and H2O2 solution was slowly added, dripped for 15min, reacted for 4h, and after the reaction was completed, 200g deionized water was added for washing, and the mixture was distilled at 60°C under reduced pressure for 2h, and vacuum dried at 70°C for 3h to obtain intermediate 2;

[0042] S3: 100 g of tetrahydrofuran, 38 g of intermediate 2, 64 g of acetic anhydride and 5 g of strong acid cation exchange resin were added into the reactor in sequence, stirred, heated to 140°C, reacted for 4 h, and after the reaction, 200 g of deionized water was added for washing, distilled at 65°C under reduced pressure for 2 h, and vacuum dried at 70°C for 3 h to obtain a modified plasticizer.

[0043] Example 4 Preparation of a bone screw baffle:

[0044] (1) Weigh 1000 g of polylactic acid, 500 g of hydroxyapatite, 60 g of modified plasticizer (prepared in Example 1), and 50 g of chain extender;

[0045] (2) polylactic acid, hydroxyapatite, modified plasticizer and chain extender were sequentially added into a high-speed blender, stirred at 100°C for 30 min, and then melt-granulated by a twin-screw extruder at an extrusion temperature of 160°C and a screw speed of 75 r / min;

[0046] (3) feeding the pellets extruded in step (2) into a 3D wire making machine to form wires with a diameter of 1.75±0.05 mm at an extrusion temperature of 170°C;

[0047] (4) The wire extruded in step (3) is fed into a fused deposition model 3D printer for printing to obtain a bone screw baffle; the nozzle temperature of the fused deposition model 3D printer is 170° C., the base plate temperature is 50° C., and the printing speed is 50 mm / s.

[0048] Example 5 Preparation of a bone screw baffle:

[0049] (1) Weigh 1100 g of polylactic acid, 550 g of hydroxyapatite, 80 g of modified plasticizer (prepared in Example 2), and 80 g of chain extender;

[0050] (2) polylactic acid, hydroxyapatite, modified plasticizer and chain extender were sequentially added into a high-speed blender, stirred at 120°C for 25 min, and then melt-granulated by a twin-screw extruder at an extrusion temperature of 170°C and a screw speed of 75 r / min;

[0051] (3) feeding the pellets extruded in step (2) into a 3D wire making machine to form wires with a diameter of 1.75±0.05 mm at an extrusion temperature of 180°C;

[0052] (4) The wire extruded in step (3) is fed into a fused deposition model 3D printer for printing to obtain a bone screw baffle; the nozzle temperature of the fused deposition model 3D printer is 180° C., the base plate temperature is 60° C., and the printing speed is 55 mm / s.

[0053] Example 6 Preparation of a bone screw baffle:

[0054] (1) Weigh 1200 g of polylactic acid, 600 g of hydroxyapatite, 100 g of modified plasticizer (prepared in Example 3), and 100 g of chain extender;

[0055] (2) polylactic acid, hydroxyapatite, modified plasticizer and chain extender were sequentially added into a high-speed blender, stirred at 140°C for 20 min, and then melt-granulated by a twin-screw extruder at an extrusion temperature of 180°C and a screw speed of 75 r / min;

[0056] (3) feeding the pellets extruded in step (2) into a 3D wire making machine to form wires with a diameter of 1.75±0.05 mm at an extrusion temperature of 190°C;

[0057] (4) The wire extruded in step (3) is fed into a fused deposition model 3D printer for printing to obtain a bone screw baffle; the nozzle temperature of the fused deposition model 3D printer is 190° C., the base plate temperature is 70° C., and the printing speed is 60 mm / s.

[0058] Comparative Example 1

[0059] A bone screw baffle, the raw material composition and process are basically the same as those of Example 5, the difference being that no modified plasticizer is added to the components.

[0060] Comparative Example 2

[0061] A bone screw baffle, the raw material composition and process are basically the same as those of Example 5, the difference being that the modified plasticizer is replaced by an equal weight of the intermediate 2 prepared in step S2 of Example 2.

[0062] Comparative Example 3

[0063] A bone screw baffle, the raw material composition and process are basically the same as those of Example 5, the difference being that the modified plasticizer is replaced with an equal weight of a modified plasticizer prepared by the following method.

[0064] The modified plasticizer in this comparative example was prepared by the following method:

[0065] S1: 100 g fatty acid and 160 g methanol were added to the reactor in sequence, stirred and mixed, and then 2 g concentrated sulfuric acid was added, the temperature was raised to 70°C, and the reaction was carried out for 6 h. After the reaction, the reaction was washed with 150 g saturated sodium carbonate solution, and then with 200 g deionized water, and the reaction was carried out by reduced pressure distillation at 50°C for 1.5 h, and vacuum drying at 60°C for 5 h to obtain intermediate 1;

[0066] S2: 100g of intermediate 1 and 10g of strong acid cation exchange resin were added to the reactor in sequence, stirred, and heated to 60°C; then 15g of formic acid and 65g of H2O2 solution (50%, V / V) were mixed, and the mixed solution of formic acid and H2O2 solution was slowly added, dripped for 13min, reacted for 6h, and after the reaction was completed, 200g of deionized water was added for washing, and the mixture was distilled at 60°C under reduced pressure for 1.5h, and vacuum dried at 60°C for 4h to obtain intermediate 2;

[0067] S3: 100 g of intermediate 2, 18 g of DL-malic acid and 0.2 g of tetrabutylammonium chloride were added to the reactor in sequence, and the temperature was raised to 120°C for reaction. The acid value of the system was measured every 0.5 h. The reaction end point was when the acid value no longer decreased. After the reaction, 200 g of deionized water was added for washing, and the reaction was carried out by reduced pressure distillation at 60°C for 1.5 h, and vacuum drying at 60°C for 4 h to obtain intermediate 3.

[0068] S4: 50 g of intermediate 3 and 37 g of acetic anhydride were added to the reactor in sequence, stirred, heated to 140°C, reacted for 3 h, and then 200 g of deionized water was added for washing after the reaction was completed. The mixture was distilled at 65°C under reduced pressure for 1.5 h, and vacuum dried at 60°C for 4 h to obtain a modified plasticizer.

[0069] Comparative Example 4

[0070] A bone screw baffle, the raw material composition and process are basically the same as those of Example 5, the difference being that the modified plasticizer is replaced with an equal weight of a modified plasticizer prepared by the following method.

[0071] The modified plasticizer in this comparative example was prepared by the following method:

[0072] S1: 87.42 g of oleic acid, 22.53 g of triethylene glycol, and 0.5498 g of tetrabutyl titanate were added to the reactor in sequence, stirred and mixed, and then nitrogen was introduced. The temperature was raised to 150°C, and the acid value was measured every 1 h. The reaction was stopped when the acid value of the system no longer decreased. After the reaction was completed, it was washed with 150 g of saturated sodium carbonate solution and then with 200 g of deionized water. It was distilled under reduced pressure at 50°C for 1.5 h and dried under vacuum at 60°C for 5 h to obtain intermediate 1;

[0073] S2: 34g of intermediate 1 and 3.4g of strong acid cation exchange resin were added to the reactor in sequence, stirred, and heated to 60°C; then 5.1g of formic acid and 22.1g of H2O2 solution (30wt%) were mixed evenly, and the mixed solution of formic acid and H2O2 solution was slowly added, dripped for 13min, reacted for 6h, and after the reaction was completed, 200g of deionized water was added for washing, and the mixture was distilled at 60°C under reduced pressure for 1.5h, and vacuum dried at 60°C for 4h to obtain intermediate 2;

[0074] S3: 40 g of intermediate 2, 20.42 g of acetic anhydride, 4 g of strong acid cation exchange resin and 20 ml of cyclohexane were added into the reactor in sequence, stirred, heated to 120°C, reacted for 6 h, and after the reaction, 200 g of deionized water was added for washing, vacuum distillation was performed at 65°C for 1.5 h, and vacuum drying was performed at 60°C for 4 h to obtain a modified plasticizer.

[0075] Comparative Example 5

[0076] A bone screw baffle, the raw material composition and process are basically the same as those of Example 5, the difference being that the modified plasticizer is replaced with an equal weight of a modified plasticizer prepared by the following method.

[0077] The modified plasticizer in this comparative example was prepared by the following method:

[0078] S1: 22 g of decenyl succinic anhydride and 32 g of 2,7-octadienol (mixture of cis and trans isomers) were added to the reactor in sequence, stirred and mixed, heated to 75°C, kept warm for 15 min, then heated to 90°C, added 0.04 g of catalyst isopropyl titanate, kept warm for 13 min, then heated to 105°C, reacted for 4 h, filtered after the reaction, transferred the filtrate to a separatory funnel, allowed to stand for stratification, removed the water layer, washed with 200 g of deionized water, then dried with 200 g of anhydrous sodium sulfate for 2 h, distilled under reduced pressure at 60°C for 1.5 h, and dried under vacuum at 60°C for 5 h to obtain intermediate 1;

[0079] S2: 120g DMF, 36g intermediate 1, and 7g strong acid cation exchange resin were added to the reactor in sequence, stirred, and heated to 60°C; then 5g formic acid and 37g H2O2 solution (30wt%) were mixed, and the mixed solution of formic acid and H2O2 solution was slowly added, dripped for 13min, reacted for 6h, and after the reaction was completed, 200g deionized water was added for washing, and the mixture was distilled at 60°C under reduced pressure for 1.5h, and vacuum dried at 60°C for 4h to obtain intermediate 2;

[0080] S3: 100 g of tetrahydrofuran, 36 g of intermediate 2, 44 g of acetic anhydride and 4 g of strong acid cation exchange resin were added into the reactor in sequence, stirred, heated to 120°C, reacted for 6 h, and after the reaction, 200 g of deionized water was added for washing, vacuum distillation was performed at 65°C for 1.5 h, and vacuum drying was performed at 60°C for 4 h to obtain a modified plasticizer.

[0081] Comparative Example 6

[0082] A bone screw baffle, the raw material composition and process are basically the same as those of Example 5, the difference being that the modified plasticizer is replaced with an equal weight of di-2-octyl phthalate.

[0083] Comparative Example 7

[0084] A bone screw baffle, the raw material composition and process are basically the same as those of Example 5, the difference being that the modified plasticizer is replaced with an equal weight of tri-isooctyl trimellitate.

[0085] The brand of polylactic acid used in Examples 4-6 and Comparative Examples 1-7 of the present application is 4032D, produced by Nature Works; the model of hydroxyapatite microspheres used is HAP08-Y, with a particle size of 25-35 μm, produced by Nanjing Junzhuo Biotechnology Co., Ltd.; the chain extender ADR-4368C used is produced by Wuhan Kemik Biomedical Technology Co., Ltd.; the strong acid cation exchange resin used is a polymer of divinylbenzene and sodium vinylbenzene sulfonate, with the brand Amberlite® IMAC HP1110 resin, purchased from Sinopharm Chemical Reagent Co., Ltd.; the 2,7-octadienol (mixture of cis and trans isomers) used in Comparative Example 5 of the present application is produced by Shanghai Aladdin Biochemical Technology Co., Ltd.

[0086] The bone screw baffles prepared in Examples 4-6 and Comparative Examples 1-7 were subjected to a bending strength test according to GB / T 1449-2005 standard. The test results are shown in Table 1.

[0087] Table 1

[0088]

[0089] It can be seen from Examples 4, 5 and 6 in Table 1 that the bending strength of the bone screw baffles prepared by the present invention is greater than 110 MPa, and has excellent bending strength.

[0090] Comparative Example 1 is a comparative example without adding modified plasticizer. It can be seen from the data in Table 1 that its bending strength is 63 MPa.

[0091] Comparative Example 2 is different from Example 5 in that the modified plasticizer is replaced with an equal weight of the intermediate 2 prepared in step S2 of Example 2, and the flexural strength thereof is 85 MPa.

[0092] Comparative Example 3 is different from Example 5 in that the modified plasticizer is replaced with an equal weight of the modified plasticizer prepared by the method in Comparative Example 3, and the flexural strength thereof is 96 MPa.

[0093] Comparative Example 4 is different from Example 5 in that the modified plasticizer is replaced with an equal weight of the modified plasticizer prepared by the method in Comparative Example 4, and the flexural strength thereof is 91 MPa.

[0094] Comparative Example 5 is different from Example 5, and the difference is that the modified plasticizer is replaced by an equal weight of the modified plasticizer prepared by replacing the (9Z,12Z,15Z)-9,12,15-octadecatriene-1-ol in step S1 of Example 2 with 2,7-octadienol (a mixture of cis and trans isomers). It can be seen from the data in Table 1 that the flexural strength is 102 MPa.

[0095] Comparative Example 6 is different from Example 5 in that the modified plasticizer is replaced with an equal weight of diisooctyl phthalate. It can be seen from the data in Table 1 that the flexural strength is 81 MPa.

[0096] Comparative Example 7 is different from Example 5 in that the modified plasticizer is replaced with an equal weight of tri(2-ethylhexyl) trimellitate. From the data in Table 1, it can be seen that the flexural strength is 88 MPa.

[0097] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. However, any equivalent changes, modifications and evolutions made by ordinary technicians in the field without departing from the scope of the technical solution of the present invention by using the technical content disclosed above are all equivalent embodiments of the present invention. At the same time, any equivalent changes, modifications and evolutions made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the technical solution of the present invention.

Claims

1. A bone screw baffle, characterized in that: The invention comprises the following raw materials in parts by weight: Polylactic acid: 100-120 parts, Hydroxyapatite: 50-60 parts, Modified plasticizer: 6-10 parts, Chain extender: 5-10 parts; The modified plasticizer is prepared by the following method: S1: Under nitrogen protection, decenyl succinic anhydride and (9Z,12Z,15Z)-9,12,15-octadecatriene-1-ol were added to the reactor in sequence, stirred and mixed, heated to 140-150°C, kept warm for 10-20 minutes, then heated to 170-180°C, and then added with catalyst isopropyl titanate, kept warm for 10-15 minutes, and then heated to 210-230°C. After reacting for 3-5 hours, intermediate 1 was obtained; S2: DMF, intermediate 1, and strong acid cation exchange resin are added to the reactor in sequence, stirred, and heated to 50-70°C; then formic acid and H2O2 solution are mixed, and the mixed solution of formic acid and H2O2 solution is slowly added, and the reaction is continued for 4-8 hours to obtain intermediate 2; S3: Tetrahydrofuran, intermediate 2, acetic anhydride, and strong acid cation exchange resin are added to the reactor in sequence, stirred, heated to 100-140° C., and reacted for 4-8 hours to obtain a modified plasticizer.

2. A bone screw baffle according to claim 1, characterized in that: In step S1, the feed mass ratio of decenyl succinic anhydride, (9Z,12Z,15Z)-9,12,15-octadecatriene-1-ol, and catalyst isopropyl titanate is 22:(60-70):(0.03-0.05).

3. The bone screw baffle according to claim 1, characterized in that: In step S2, the feed mass ratio of DMF, intermediate 1, strong acid cation exchange resin, formic acid, and H2O2 solution is 120:(34-38):(6-8):(14-18):(36-38).

4. The bone screw baffle according to claim 1, characterized in that: In step S3, the feed mass ratio of tetrahydrofuran, intermediate 2, acetic anhydride, and strong acid cation exchange resin is 100:(32-38):(60-64):(3-5).

5. The bone screw baffle according to claim 1, characterized in that: The hydroxyapatite is hydroxyapatite microspheres.

6. The bone screw baffle according to claim 1, characterized in that: The chain extender is ADR-4368C.

7. A method for preparing a bone screw baffle according to any one of claims 1 to 6, characterized in that: The following steps are involved: (1) Weigh by weight: polylactic acid: 100-120 parts, hydroxyapatite: 50-60 parts, modified plasticizer: 6-10 parts, chain extender: 5-10 parts; (2) Adding polylactic acid, hydroxyapatite, modified plasticizer and chain extender into a high-speed blender in sequence, stirring at 100-140°C for 20-30 minutes, and then melt granulating through a twin-screw extruder at an extrusion temperature of 160-180°C and a screw speed of 75 r / min; (3) feeding the extruded particles in step (2) into a 3D wire making machine to form wires with a diameter of 1.75±0.05 mm at an extrusion temperature of 170-190°C; (4) The wire extruded in step (3) is fed into a fused deposition model 3D printer for printing to obtain a bone screw baffle; the nozzle temperature of the fused deposition model 3D printer is 170-190° C., the base plate temperature is 50-70° C., and the printing speed is 50-60 mm / s.

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