Preparation method of medical-grade zirconium oxide cleaving needle

Abstract

The invention relates to the field of medical apparatus and instruments, and discloses a preparation method of a medical grade zirconia cleaving needle, which comprises the following steps: adding yttria-stabilized zirconia, a dispersant, a binder, a hot flux and a lubricant into an internal mixer for internal mixing according to parts by weight; heating the internally mixed raw materials for 1.5-2.5 hours at 170-190 DEG C through a porous limestone mold with the pore diameter of 10 microns, and carrying out iron removal treatment; carrying out injection molding on the deironed granular raw materials at the temperature of 140-180 DEG C to prepare a green body; the green body is subjected to glue discharging treatment at the temperature of 550 DEG C to 650 DEG C and sintering treatment at the temperature of 1450 DEG C to 1550 DEG C; and finally, finish machining of the ceramic cleaving needle is completed through cylindrical grinding and mirror polishing. The prepared ceramic cleaving needle has high strength, high toughness and excellent surface smoothness, can be widely applied to operations such as medical puncture, suture and infusion, and has good biocompatibility and application value.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and particularly to a preparation method of a medical-grade zirconia splitting needle. Background Art

[0002] Medical splitting needles are widely used in medical operations such as puncture, infusion, suture, and skin perforation. Their performance and materials directly affect the safety of the medical process and the rehabilitation quality of patients. In the prior art, medical splitting needles are mainly made of metal materials. Although metal splitting needles have high hardness and sharpness, there are still obvious deficiencies in their biosecurity and service life. Metal materials are prone to oxidation and corrosion, and are likely to rust in a high-humidity environment or when exposed to medicinal liquids, which not only affects the function of the instrument but also may cause secondary infection to patients. In addition, bacteria or drug residues are likely to adhere to the metal surface, making it difficult to clean and further increasing the risk of postoperative infection.

[0003] In contrast, due to their excellent biocompatibility, high strength, and corrosion resistance, ceramic materials have gradually become a research hotspot in the medical field. However, the current preparation technology of ceramic medical devices still faces a series of challenges. For example, the influence of iron impurities on the material purity and performance has not been effectively solved, resulting in difficulty in meeting the medical-grade standards for product quality. At the same time, the poor fluidity of the slurry and the inaccurate mold forming limit the realization of complex-structured ceramic splitting needles, and the functional expandability of the products is weak. Therefore, developing a preparation method for high-purity, high-performance, and multifunctional ceramic splitting needles, which not only meets medical needs but also solves the defects of the prior art, has important research and application value. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a preparation method of a medical-grade zirconia splitting needle, which solves the problems of high infection risk, insufficient performance, and single function caused by material oxidation, rust, and surface impurities in existing medical splitting needles.

[0005] To achieve the above purposes, the present invention is realized through the following technical solutions: A preparation method of a medical-grade zirconia splitting needle, comprising the following steps: (1) Raw material preparation: According to the weight ratio, 65-75 parts of yttrium-stabilized zirconia, 2-4 parts of dispersant, 13-17 parts of binder, 1.5-2.5 parts of hot melt agent, and 8-12 parts of lubricant are added to a mixer to obtain a mixed raw material. (2) Iron removal treatment: The mixed raw material is added to a porous limestone mold and heated at 170-190 °C for 1.5-2.5 hours to remove iron impurities. (3) Injection molding: The raw material after iron removal is injection molded at a temperature of 140-180 °C and a pressure of 50-100 Pa to obtain a green body. (4) Green body firing: Debinding the green body, after maintaining a constant temperature at 550 - 650 °C for 18 - 22 hours, heating up to 1450 - 1550 °C and sintering for 1.5 - 2.5 hours, then cooling to room temperature to obtain a dense ceramic splitting needle; (5) Polishing process: Polishing the sintered ceramic splitting needle.

[0006] Preferably, the dispersant is one or both of ammonium salts and glycerol.

[0007] Preferably, the binder is one or more of polypropylene, polyethylene, stearic acid, and dibutyl phthalate.

[0008] Preferably, in the raw material preparation, the internal mixer is operated at 170 - 190 °C for 1.5 - 2 hours and then cooled to 100 - 130 °C.

[0009] Preferably, in the iron removal treatment, the pore diameter of the porous limestone mold used is 1 - 5 μm.

[0010] Preferably, in the injection molding, the injection speed is 50 - 90 mm / s.

[0011] Preferably, the heating rate of the debinding treatment is 1 - 3 °C / min, and the cooling rate after sintering is 2 - 5 °C / min.

[0012] Preferably, the polishing process includes external cylindrical grinding and tip planar grinding.

[0013] The present invention also provides a medical-grade zirconia splitting needle prepared by the described method.

[0014] Preferably, the medical-grade zirconia splitting needle includes one or more of the following types: A splitting needle with a hollow infusion tube for targeted drug delivery; A splitting needle for suture operation with a tail rope hole; A splitting needle equipped with a detachable needle for disposable needle replacement.

[0015] The present invention provides a preparation method for a medical-grade zirconia splitting needle, having the following beneficial effects: 1. By using a zirconia ceramic splitting needle, the present invention can significantly reduce the infection phenomenon caused by traditional splitting needles and has a profound application prospect in medical care.

[0016] 2. By adding an internal mixer iron removal process and using a micron-porous limestone mold to adsorb and remove iron, the present invention can significantly reduce the iron impurities in the product caused by internal mixing or raw materials, which is of great significance in medical-grade zirconia splitting needles. Description of the Drawings

[0017] Figure 1 Schematic diagram of the method flow of the present invention; Figure 2 Schematic diagram of Embodiment 1 of the present invention; Figure 3 Schematic diagram of Embodiment 2 of the present invention; Figure 4 Schematic diagram of Embodiment 3 of the present invention; Figure 5 Schematic diagram of the experimental object in the comparative experiment of the present invention. Detailed implementation manners

[0018] Next, in combination with the accompanying drawings of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts shall fall within the protection scope of the present invention.

[0019] Please refer to the attached Figure 1 , the present invention provides a preparation method of a medical-grade zirconia splitting needle, which solves the problems of traditional medical splitting needles in oxidation, rusting, and easy infection through the optimized design of process parameters. The present invention prepares a medical-grade zirconia splitting needle with high strength, high toughness, and biocompatibility through raw material ratio, iron removal process, forming technology, and sintering process.

[0020] As Figure 1 shown, the preparation method of the medical-grade zirconia splitting needle may include the following steps: S1. Add raw materials to a mixer according to the weight ratio, and obtain the mixed raw materials through mixing; S2. Add the mixed raw materials into a porous limestone mold to remove iron impurities; S3. Inject and mold the raw materials after iron removal to obtain a green body; S4. Perform debinding treatment on the green body to obtain a dense ceramic splitting needle; S5. Perform polishing treatment on the ceramic splitting needle.

[0021] Next, each step of the method of the present invention will be described in detail.

[0022] For step S1, in this embodiment, the raw material preparation of step S1 adopts a formulation system with yttria-stabilized zirconia as the main component to ensure that the material has high strength, high toughness, and excellent biocompatibility. Specifically, by weight, 65-75 parts of yttria-stabilized zirconia, 2-4 parts of dispersant, 13-17 parts of binder, 1.5-2.5 parts of hot melt agent, and 8-12 parts of lubricant are selected for combination. The selection and ratio of each component are optimized to meet the requirements of subsequent injection molding and sintering processes.

[0023] Yttria-stabilized zirconia has good mechanical properties and biocompatibility. To further improve the performance of ceramic splitting needles, the purity of the yttria-stabilized zirconia used in this embodiment is not less than 99%. By adding yttria (Y 2 O 3 ), as a stabilizer, it can stabilize zirconia in the equilibrium state of tetragonal phase and partial monoclinic phase, thus significantly improving the toughness and crack resistance of the material.

[0024] The dispersant plays a role in improving the dispersibility of zirconia particles in this embodiment, avoiding the agglomeration phenomenon between particles, and thus improving the uniformity of the raw materials. The selection of the dispersant includes ammonium salts, glycerol or their mixtures, which reduce the van der Waals force between particles through surface adsorption, enabling the zirconia powder to be evenly distributed throughout the system during the subsequent internal mixing process.

[0025] As one of the main components in the system, the binder functions to enhance the plasticity and green strength of the raw materials. The binder selected in this embodiment includes one or more of polypropylene, polyethylene, stearic acid, and dibutyl phthalate. Its principle of action is to form a stable network structure at high temperature through the flexibility of molecular chains, form a good bond with zirconia particles, and provide sufficient mechanical strength to meet the requirements of injection molding and demolding.

[0026] The addition of the hot melt adhesive is to further enhance the thermoplasticity of the system. In this embodiment, ethylene-vinyl acetate copolymer (EVA) is selected as the hot melt adhesive, which can reduce the melt viscosity of the system during the heating process and improve the fluidity of the raw materials during the injection molding process.

[0027] The lubricant is used to reduce the friction between the mold and the raw materials during the injection molding process. Paraffin is used as the lubricant in this embodiment. Its low melting point characteristic can effectively reduce the friction resistance during the internal mixing and injection molding stages, avoid mold wear, and ensure the uniform distribution of the raw materials in the mold.

[0028] After the raw material ratio is completed, the above components are added to an internal mixer in sequence for mixing. During the internal mixing process, the temperature of the internal mixer is set to 170 - 190 °C to ensure that the dispersant, binder, and hot melt adhesive are fully dissolved and coat the zirconia particles in the high-temperature environment, forming a uniform mixture. The internal mixing time is controlled within 1.5 - 2 hours. Within this time range, it can ensure the full mixing of each component and avoid the decline of material performance caused by overheating.

[0029] After the internal mixing is completed, stop heating, and let the temperature of the internally mixed raw materials cool naturally to 100 - 130 °C, and then take them out of the internal mixer. After cooling to room temperature, store the obtained raw materials for future use to ensure that their uniformity and stability can meet the requirements of the subsequent injection molding process.

[0030] The kneading raw materials prepared by the above method have high uniformity and good fluidity, providing a processing basis for subsequent steps.

[0031] For step S2, in this embodiment, the iron removal treatment in step S2 aims to effectively remove iron impurities in the kneading raw materials through a porous limestone mold, thereby improving the purity of the zirconia ceramic material and ensuring the stability of the material properties during the subsequent sintering process. The implementation details of this step are as follows: After the kneading raw materials are prepared in step S1, they are evenly distributed in the porous limestone mold. The pore size range of the porous limestone mold is controlled at 1 - 5 μm, and its pore structure can provide good adsorption capacity and permeability. The pore size selection of the mold has been optimized. Too large a pore size will reduce the adsorption efficiency, while too small a pore size may cause the kneading raw materials to be unable to penetrate, thus affecting the iron removal effect.

[0032] The heating process is completed in a closed heating device. The porous limestone mold filled with the kneading raw materials is placed in the heating device, and the heating temperature is controlled at 170 - 190 °C to ensure that the iron impurities in the raw materials are in an easily migratory state. This temperature range is determined based on the diffusion characteristics of iron impurities in the ceramic matrix. Too low a temperature is not sufficient to cause the impurities to migrate into the mold pores, while too high a temperature may cause the binder or hot melt agent to volatilize prematurely, affecting the subsequent process.

[0033] At the above heating temperature, the heating time is maintained for 1.5 - 2.5 hours. The setting of the heating time is to ensure that the iron impurities fully migrate into the mold pores, while preventing the attenuation of material properties caused by long - term heating. Through the physical adsorption of the porous mold, the iron impurities are fixed in the mold, thereby realizing the purification treatment of the raw materials.

[0034] After the heating is completed, the porous mold is taken out of the heating device and naturally cooled to room temperature. The cooled raw materials are separated from the mold. To avoid secondary contamination of the raw materials by metal tools, in this embodiment, ceramic tools are used to cut the cooled raw materials into slices. After cutting, the raw materials are further crushed by a ceramic crusher to obtain granular raw materials. The use of the above - mentioned ceramic tools can avoid the influence of impurities brought in by metal tools on the material purity.

[0035] After the porous limestone mold is used, the iron impurities adsorbed in its pores can be removed by means such as pickling or high - temperature roasting to ensure that the mold can be reused, reducing production costs. Dilute hydrochloric acid (concentration 5% - 10%) is usually used for pickling, and the temperature of high - temperature roasting is generally controlled at 800 - 1000 °C.

[0036] Through the above iron removal treatment, the iron impurity content in the kneading raw materials is significantly reduced, providing a high-purity raw material basis for subsequent injection molding and sintering. The reduction of iron impurities not only helps to improve the mechanical properties and density of zirconia ceramics, but also reduces the porosity of the products, improving the biosecurity and service life of the products.

[0037] For step S3, in this embodiment, the injection molding in step S3 is to prepare the granular raw materials treated in step S2 into green bodies of ceramic splitting needles that meet the design requirements through the injection molding process. This step is the key to realizing the shaping of the ceramic splitting needle, and the specific process and technical parameters are as follows.

[0038] During the implementation process, the granular raw materials are first loaded into the hopper of the injection molding machine and preheated in the hopper. The preheating temperature is controlled at 120-140 °C. This temperature range can effectively soften the binder and hot melt agent in the raw materials, making them in a suitable flow state, while avoiding problems such as thermal decomposition or too low viscosity caused by too high temperature. The preheating time is usually controlled at 5-15 minutes to ensure that the granular raw materials are evenly heated.

[0039] The injection molding machine mold is customized according to the design requirements of the ceramic splitting needle. The design of the mold includes parts such as the needle tip, hollow tube, and tail connection structure. The mold material is selected as steel or high-strength ceramic with high temperature resistance and low friction coefficient to ensure stability and durability under high temperature and high pressure conditions. The surface of the mold is polished, and the roughness is controlled at Ra≤0.2μm to reduce the frictional resistance during the forming process of the green body and improve the smoothness of injection molding.

[0040] During injection molding, the temperature of the injection molding machine is set at 140-180 °C. This range is determined based on the thermoplastic properties of the raw materials. Too low a temperature will cause insufficient fluidity of the raw materials and the mold cannot be fully filled; while too high a temperature may cause the decomposition of the binder, resulting in insufficient strength of the green body. The injection pressure is set at 50-100 Pa. This pressure range can ensure that the raw materials fully fill all parts of the mold, especially the detailed structures such as the hollow tube and the needle tip.

[0041] In order to further optimize the forming effect, the injection speed in this embodiment is set at 50-90 mm / s. The control of the injection speed is mainly to avoid streamline defects of the raw materials in the mold caused by too fast filling, while ensuring a high production efficiency. The injection process is usually divided into three stages: rapid filling stage, deceleration compaction stage, and pressure holding and cooling stage. The parameters of each stage are adjusted according to the complexity of the mold and the performance of the injection molding machine.

[0042] After injection molding is completed, the green body is removed from the mold by opening the mold. To avoid cracking or warping of the green body due to temperature difference, the green body is cooled to room temperature by slow cooling. The cooled green body has certain mechanical strength and shape stability, and the geometric dimension deviation of its tip, hollow tube, and tail structure is controlled within ±0.1 mm.

[0043] In the injection molding process of this step, through the precise control of temperature, pressure, and speed, as well as the optimization of mold design, the molding quality and dimensional accuracy of the green body are ensured.

[0044] Through the above injection molding steps, the ceramic splitting needle green body prepared by the present invention has high precision, high uniformity, and good adaptability for subsequent processing, and can effectively meet the requirements of different medical uses for the shape and function of ceramic splitting needles.

[0045] For step S4, in this embodiment, the firing of the green body in step S4 is to convert the ceramic splitting needle green body into a dense ceramic structural part through high-temperature debinding and sintering processes, which is a key step to achieve high mechanical properties and excellent surface quality of ceramic splitting needles.

[0046] In this step, the green body is first subjected to debinding treatment to completely remove organic components such as binders, hot melt agents, and lubricants. The debinding process is carried out in a high-temperature furnace, and the heating rate is controlled at 1 - 3 °C / min to avoid the generation of thermal stress or cracks inside the green body due to too rapid temperature change. The debinding temperature is gradually increased to 550 - 650 °C and kept constant at this temperature range for 18 - 22 hours. This constant temperature time can ensure the complete decomposition and volatilization of organic components and avoid pore problems caused by organic residue during the subsequent sintering process.

[0047] After debinding is completed, the green body continues to be subjected to high-temperature sintering treatment. The sintering temperature is set at 1450 - 1550 °C and kept constant at this temperature range for 1.5 - 2.5 hours. During the sintering process, through solid-phase diffusion and grain rearrangement, the zirconia particles gradually become densified. In order to further improve the sintering density, in this embodiment, high-purity yttria-stabilized zirconia (Y 2 O 3 with a content greater than 99%) is selected as the main raw material. The stabilizing effect of yttria can inhibit the abnormal growth of grains and at the same time improve the fracture toughness and flexural strength of the ceramic material.

[0048] During the sintering process, the tetragonal phase structure of zirconia gradually transforms into a stable tetragonal / monoclinic mixed state. This phase structure optimization significantly improves the mechanical properties of the ceramic splitting needle, including its flexural strength and impact resistance. The atmosphere in the sintering furnace can be selected as air or protective atmosphere (such as nitrogen) according to requirements to reduce the risk of surface oxidation or impurity diffusion.

[0049] After sintering is completed, the green body needs to be slowly cooled to room temperature, and the cooling rate is controlled at 2-5 °C / min. Slow cooling can effectively prevent cracks or warping caused by thermal shock, and at the same time helps to further release the residual stress inside the ceramic, ensuring the dimensional stability and integrity of the product.

[0050] The ceramic splitting needle after sintering already has high density and surface quality. The porosity of the material after sintering is significantly reduced, usually controlled below 0.1%; its microhardness can reach above 1200 HV, and the flexural strength is increased to above 900 MPa, providing a reliable guarantee for subsequent processing and actual use.

[0051] In this step, by optimizing the debinding and sintering process parameters, the uniformity and structural integrity inside the ceramic splitting needle are ensured. The dimensional deviation of the splitting needle after high-temperature sintering is controlled within ±0.02 mm, which can meet the use requirements of medical devices with high precision, high strength and high toughness.

[0052] For step S5, in this embodiment, the polishing process of step S5 is to perform dimensional adjustment and surface treatment on the ceramic splitting needle after sintering through a series of processing means to further improve its surface finish, use safety and aesthetics. This step is an important link to realize the final functionalization of the ceramic splitting needle.

[0053] The ceramic splitting needle after sintering is first subjected to rough machining, mainly using an external cylindrical grinder for dimensional adjustment. In this embodiment, the machining accuracy of the external cylindrical grinder is controlled within ±0.02 mm, which is used to trim the external shape of the ceramic splitting needle to make it meet the geometric requirements of the predetermined design. During this process, the grinding speed and grinding force need to be adjusted according to the hardness and toughness of the ceramic to avoid cracks or chipping on the surface of the ceramic splitting needle caused by excessive processing stress.

[0054] The treatment of the tip part is further trimmed using a surface grinder. The surface grinder can achieve high-precision surface grinding to ensure that the tip of the ceramic splitting needle has uniform sharpness and ideal geometric shape. The selection of the grinding angle is designed according to the use of the splitting needle. For example, the sharp angle of the tip is usually controlled within the range of 15°-30°, which not only ensures the puncture function but also avoids the reduction of mechanical strength due to the too thin tip.

[0055] After rough machining is completed, there may still be microscopic unevenness or small defects on the surface of the ceramic splitting needle, so further mirror polishing treatment is required. The polishing equipment uses a high-precision polishing machine and combines diamond abrasives for processing, and the polishing time is controlled within 20-40 minutes. The core of the polishing process is to use the high hardness and fine particle size of diamond abrasives to gradually remove the microscopic unevenness on the ceramic surface through mechanical grinding, reducing its surface roughness to Ra < 0.02 μm.

[0056] During the polishing process, circulating cooling water is required to cool the ceramic splitting needle in real time to avoid an increase in material thermal stress or surface damage caused by high temperature. The flow rate of the cooling water is controlled at 0.5 - 1 L / min to ensure that the processing area always remains at a low temperature state. After polishing, an ultrasonic cleaning device is used to thoroughly clean the splitting needle to remove residual abrasive particles and processing debris on the surface, ensuring that the finished product is clean and pollution-free.

[0057] After the above polishing process steps, the surface finish and sharpness of the ceramic splitting needle reach the medical grade standard. The mirror-polished ceramic splitting needle not only reduces the possibility of bacterial attachment but also significantly improves its puncture performance and usage comfort. The dimensional accuracy and surface quality of the final product fully meet the relevant technical requirements of medical devices, ensuring its safety and reliability in practical applications.

[0058] Generally speaking, the present invention uses high-purity yttrium-stabilized zirconia as the base material, and through steps such as precise raw material ratio, internal mixer treatment, iron removal process, injection molding, high-temperature sintering, and polishing process, a ceramic splitting needle with high strength, high toughness, and excellent biocompatibility is prepared. The present invention optimizes the iron removal treatment to reduce the iron impurity content, improving the densification and mechanical properties of the material; at the same time, through precise control of the parameters of the injection molding and sintering processes, high-precision forming of complex geometric structures is achieved; the final mirror polishing further reduces the surface roughness and enhances the usage safety and antibacterial properties of the product. The ceramic splitting needle of the present invention is widely applicable to various medical scenarios such as medical puncture, infusion, and suture, and has important application value and promotion prospects.

[0059] To better understand the present invention, the above method will be described in detail below in conjunction with specific embodiments.

[0060] Example 1: Yttrium-stabilized zirconia ceramic splitting needle with infusion function In this embodiment, a yttrium-stabilized zirconia ceramic splitting needle with an infusion function is prepared. As Figure 2 shown, the splitting needle breaks through the skin surface layer through the needle tip 13, and the infusion hollow tube 12 realizes the directional delivery of the liquid medicine. The threaded interface 11 is used to fix the ceramic needle on the infusion set, and the infusion set also serves as the operating handle.

[0061] Specific preparation steps: 1. Raw material preparation: Weigh 70 parts of yttrium-stabilized zirconia, 3 parts of dispersant, 15 parts of binder, 2 parts of hot melt agent, and 10 parts of lubricant by weight, add them to an internal mixer, and knead at 170 - 190 °C for 2 hours to form a uniform kneaded raw material. After cooling to 120 °C, take it out and set aside.

[0062] 2. Iron removal treatment: Add the kneaded raw materials into a porous limestone mold with a pore size of 1 - 5 μm, heat at 170 - 190 °C for 2 hours, and adsorb iron impurities through the pores of the mold. After cooling to room temperature, slice the raw materials with a ceramic tool, and then crush them into granular raw materials with a ceramic crusher.

[0063] 3. Injection molding: Load the iron-removed granular raw materials into the hopper of an injection molding machine, preheat to 130 °C, and carry out injection molding at 140 - 180 °C and 50 - 100 Pa. The mold design includes a needle head 13, a hollow tube 12, and a threaded interface 11. Control the injection speed at 70 mm / s, cool and demold after molding to obtain a green body.

[0064] 4. Green body firing: Carry out debinding treatment on the green body, heat it at a rate of 1 °C / min to 600 °C, keep it at a constant temperature for 20 hours, then continue to heat to 1500 °C and sinter for 2 hours. After sintering is completed, cool to room temperature at a rate of 2 °C / min to obtain a dense ceramic suture needle blank.

[0065] 5. Polishing process: Use an external cylindrical grinder and a surface grinder to trim the dimensions of the hollow tube 12 and the needle head 13 to ensure that their geometric accuracy is within the range of ±0.02 mm. Carry out finish machining on the threaded interface 11, and polish to reduce the surface roughness to Ra < 0.02 μm.

[0066] The final product realizes the precise delivery of the liquid medicine and convenient operation, and is applicable to first aid and surgical infusion operations.

[0067] Example 2: Zirconia ceramic suture needle for suturing In this example, a zirconia ceramic suture needle convenient for suturing operations is prepared. As Figure 3 shown, the suture needle is punctured through the needle head 22, and the tail thread hole 21 is used for threading to realize medical suture operations.

[0068] Specific preparation steps: 1. Raw material preparation: Weigh 68 parts of yttrium-stabilized zirconia, 3.5 parts of dispersant, 14 parts of binder, 2.5 parts of hot melt agent, and 9.5 parts of lubricant by weight, add them into a kneader, knead at 180 °C for 1.8 hours, and take them out for standby after cooling to 120 °C.

[0069] 2. Iron removal treatment: Load the kneaded raw materials into a porous limestone mold with a pore size of 2 μm, heat to 175 °C and keep for 2 hours to remove iron impurities. After cooling to room temperature, slice and crush the raw materials into granular form with a ceramic tool.

[0070] 3. Injection molding: The granular raw material is injection molded at a temperature of 140 - 180°C. The mold design includes the structure of the needle tip 22 and the tail rope hole 21. The injection pressure is set at 80 Pa, and the injection speed is 60 mm / s. After molding, it is cooled and demolded to obtain the green body of the suture needle that meets the design requirements.

[0071] 4. Firing of green body: The green body is heated at a rate of 2°C / min to 550°C for debinding. After maintaining a constant temperature for 20 hours, it is further heated to 1450°C and sintered for 2 hours. After sintering is completed, it is slowly cooled to room temperature to ensure no cracks inside the ceramic.

[0072] 5. Polishing process: The needle tip 22 is processed by surface grinding to ensure its puncture performance. The sharpness of the needle tip is controlled between 15° and 30°. The tail rope hole 21 is subjected to mirror polishing for 30 minutes to make its surface finish reach Ra < 0.02 μm.

[0073] The finally prepared zirconia ceramic suture needle meets the medical suture requirements, has high precision and high strength, and is suitable for suture operations in surgical procedures.

[0074] Example 3: Ceramic splitting needle for only puncturing the wound In this example, a ceramic splitting needle with a detachable needle tip is prepared for medical operations that only require puncturing the wound. As Figure 4 shown, the splitting needle consists of an operating handle 31, a connecting buckle 32, and a detachable needle tip 33, and can achieve one-time replacement of the needle tip.

[0075] Specific preparation steps: 1. Raw material preparation: Weigh 70 parts of yttria-stabilized zirconia, 3 parts of dispersant, 15 parts of binder, 2 parts of hot melt agent, and 10 parts of lubricant by weight, and add them to a mixer and mix at 175°C for 2 hours. After cooling to 125°C, take it out and set aside.

[0076] 2. Iron removal treatment: The mixed raw material is loaded into a porous limestone mold with a pore size of 3 μm and heated at 170°C for 2 hours to remove iron impurities. After cooling, it is cut and broken into granular raw materials with ceramic tools.

[0077] 3. Injection molding: The granular raw material is preheated to 135°C in an injection molding machine, and then injection molded at a temperature of 140 - 180°C. The mold design includes the structure of the operating handle 31, the connecting buckle 32, and the detachable needle tip 33. The injection pressure is controlled at 70 Pa, and the injection speed is 50 mm / s. After injection molding, it is cooled and demolded to obtain the green body with a detachable needle tip structure.

[0078] 4. Green body firing: The green body is heated at a rate of 1.5 °C / min to 600 °C for debinding treatment. After maintaining a constant temperature for 22 hours, it is heated to 1500 °C and sintered for 2 hours, and finally slowly cooled to room temperature.

[0079] 5. Polishing process: The surface of the needle tip 33 is finely polished for 25 minutes, and the final surface roughness reaches Ra < 0.02 μm. The connecting surface of the link buckle 32 and the handle 31 is polished to ensure smooth and tight assembly.

[0080] The ceramic splitting needle prepared by the above steps realizes the separation design of the operating handle and the needle tip, which is convenient for medical staff to replace the needle tip and is suitable for small medical operations and wound treatment.

[0081] In order to verify the effects of the raw material ratio, mixing process and iron removal treatment on the slurry performance and finished product quality in the preparation method of the present invention, multiple groups of experiments (Experiment 1 - Experiment 4) and comparative experiments (Comparative Experiment 1 - Comparative Experiment 3) were designed. Each experiment optimized or adjusted the content of yttria-stabilized zirconia, the proportion of lubricant and the iron removal process respectively, and tested their effects on the slurry viscosity, iron impurity content and the surface state of the finished product.

[0082] Experimental design and parameters 1. Experimental groups (Experiment 1 - Experiment 4) The experimental groups were operated according to the ratio and process parameters within the scope of the present invention, where: The content of yttria-stabilized zirconia is 65 - 75 parts.

[0083] The proportions of the dispersant, binder, hot melt agent and lubricant are 2 - 4 parts, 13 - 17 parts, 1.5 - 2.5 parts, 8 - 12 parts respectively (except for Experiment 3 and Experiment 4, which are studied as special cases).

[0084] Iron removal treatment was carried out using a porous limestone mold with a pore size of 10 μm.

[0085] 2. Comparative experimental groups (Comparative Experiment 1 - Comparative Experiment 3) The comparative experimental groups did not adopt the optimization scheme of the present invention, specifically including: No iron removal treatment was carried out in Comparative Experiment 1 and Comparative Experiment 2.

[0086] In Comparative Experiment 3, an iron removal mold with a pore size of 100 μm was used to observe the iron impurity removal effect.

[0087] The experimental results are shown in the following table: 1. Mixing performance and slurry viscosity The mixing performance of each experimental group and comparative experimental group is as follows: Experiments 1 and 2: The slurry viscosities were 300 mPa.s and 500 mPa.s respectively, showing good fluidity and being suitable for injection molding.

[0088] Experiment 3: Since the lubricant content was reduced to 5 parts, the slurry viscosity increased significantly to 2000 mPa.s and the fluidity decreased significantly.

[0089] Experiment 4: The lubricant was further reduced to 3 parts, resulting in the slurry being too viscous to measure the viscosity, showing severe lack of fluidity.

[0090] Comparative Experiments 1, 2, and 3: The viscosities were similar to those of Experiments 1 and 2, but no further performance optimization was observed.

[0091] The proportion of the lubricant has a significant impact on the fluidity of the slurry. Too low a lubricant content (such as in Experiments 3 and 4) will significantly reduce the fluidity of the slurry, which is not suitable for the preparation requirements of the present invention. The optimized lubricant content (8 - 12 parts) in the present invention can significantly improve the slurry performance and ensure its fluidity and uniformity.

[0092] 2. Iron removal effect and iron impurity content The iron removal processes and iron impurity contents of each experimental group and comparative experimental group are as follows: Experiments 1 and 2: Using a 10μm pore size mold, the iron impurity contents were 8 PPM and 10 PPM respectively, and there were no obvious impurity points on the surface of the finished products.

[0093] Experiment 3: Due to the poor fluidity of the slurry, the iron removal effect was affected and the iron impurity content increased to 300 PPM.

[0094] Experiment 4: No iron removal treatment was carried out, and the iron impurity content could not be measured.

[0095] Comparative Experiments 1 and 2: No iron removal treatment was carried out, and the iron impurity contents were as high as 400 PPM and 500 PPM.

[0096] Comparative Experiment 3: Using a 100μm pore size mold, the iron impurity content was 200 PPM and the removal effect was not good.

[0097] In the present invention, using an iron removal mold with a pore size of 10μm can significantly reduce the iron impurity content to below 10 PPM. While not carrying out iron removal treatment (Comparative Experiments 1 and 2) or using a large pore size mold (Comparative Experiment 3) both result in a significant increase in the iron impurity content, verifying the effectiveness of the iron removal process of the present invention.

[0098] 3. Surface state and performance of the finished products The surface qualities of the finished products of each experimental group and comparative experimental group are as follows: Experiment 1 and Experiment 2: The surface of the finished product is smooth, without obvious impurity points, with high dimensional accuracy, fully meeting the usage requirements of medical devices.

[0099] Experiment 3: Due to poor fluidity of the slurry and high iron impurity content, cracks appear on the surface of the finished product, and the mechanical strength decreases significantly.

[0100] Experiment 4: Due to too low lubricant content and no iron removal, subsequent processing cannot be completed.

[0101] Comparative Experiment 1 and Comparative Experiment 2: There are many impurity points on the surface of the finished products, affecting the performance and appearance.

[0102] Comparative Experiment 3: The impurity points are fewer than those in Comparative Experiment 1 and 2, but the surface is still not smooth and the dimensional accuracy is not high.

[0103] The optimized scheme of the present invention can effectively improve the surface quality of the finished product, reduce impurity points and improve dimensional accuracy. The unoptimized comparative experimental groups have poor surface quality of the finished product due to excessive iron impurities or poor slurry performance, verifying the superiority of the optimized scheme.

[0104] Conclusion: 1. Optimization of raw material ratio The proportion of the lubricant significantly affects the fluidity of the slurry and the quality of the finished product. The optimized lubricant content (8 - 12 parts) of the present invention can ensure stable slurry performance, while a low lubricant content (such as in Experiment 3 and Experiment 4) will lead to too high viscosity, affecting the subsequent process.

[0105] 2. Importance of iron removal process Using a 10μm pore size mold for iron removal is the key to achieving iron impurity removal. The iron impurity content in the optimized scheme (Experiment 1 and Experiment 2) is less than 10 PPM, ensuring high purity and high quality of the finished product. Failure to perform iron removal (Comparative Experiment 1, 2) or using a large pore size mold (Comparative Experiment 3) both result in a significant increase in iron impurity content.

[0106] 3. Superiority of the performance of the finished product The surface of the finished product prepared by the optimized scheme is smooth, without obvious impurity points, with high dimensional accuracy, and is suitable for medical use. The comparative experimental groups have poor surface quality of the finished product due to unoptimized ratio or process, verifying the necessity and superiority of the method of the present invention.

[0107] The above experiments fully prove that the optimized method of the present invention has significant advantages in terms of slurry performance, iron impurity removal and finished product quality, and is applicable to the preparation of medical-grade zirconia splitting needles.

[0108] Although embodiments of the present invention have been shown and described, those of ordinary skill in the art will appreciate that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a medical grade zirconium oxide splitting needle, characterized in that: The following steps are involved: (1) Raw material preparation: according to the weight ratio, 65-75 parts of yttria-stabilized zirconia, 2-4 parts of dispersant, 13-17 parts of binder, 1.5-2.5 parts of hot melt agent and 8-12 parts of lubricant are added into an internal mixer, and internally kneaded to obtain internally kneaded raw materials; (2) Iron removal treatment: Add the banburying raw materials into a porous limestone mold and heat at 170-190°C for 1.5-2.5 hours to remove iron impurities; (3) Injection molding: The raw material after iron removal is injection molded at a temperature of 140 to 180° C. and a pressure of 50 to 100 Pa to obtain a green body; (4) Firing of green parts: After debinding the green parts, the green parts are kept at a constant temperature of 550-650°C for 18-22 hours, the temperature is raised to 1450-1550°C and sintered for 1.5-2.5 hours, and then cooled to room temperature to obtain a dense ceramic splitting pin; (5) Polishing: Polish the sintered ceramic splitting needle.

2. The method for preparing a medical grade zirconium oxide splitting needle according to claim 1, characterized in that: The dispersant is one or both of ammonium salt and glycerol.

3. The method for preparing a medical grade zirconium oxide splitting needle according to claim 1, characterized in that: The binder is one or more of polypropylene, polyethylene, stearic acid, and dibutyl phthalate.

4. The method for preparing a medical grade zirconium oxide splitting needle according to claim 1, characterized in that: In the preparation of the raw materials, the banburying is carried out at 170-190° C. for 1.5-2 hours and then cooled to 100-130° C.

5. The method for preparing a medical grade zirconium oxide splitting needle according to claim 1, characterized in that: In the iron removal process, the porous limestone mold used has a pore size of 1 to 5 μm.

6. The method for preparing a medical grade zirconium oxide splitting needle according to claim 1, characterized in that: In the injection molding, the injection speed is 50 to 90 mm / s.

7. The method for preparing a medical grade zirconium oxide splitting needle according to claim 1, characterized in that: The heating rate of the debinding treatment is 1-3°C / min, and the cooling rate after sintering is 2-5°C / min.

8. The method for preparing a medical grade zirconium oxide splitting needle according to claim 1, characterized in that: The polishing process includes cylindrical grinding and needle tip surface grinding.

9. A medical grade zirconium oxide splitting needle, characterized in that: The medical-grade zirconia splitting needle is prepared by the method described in any one of claims 1-8.

10. A medical grade zirconium oxide splitting needle according to claim 9, characterized in that: The medical grade zirconia splitting needles include one or more of the following types: Splitting needle with hollow infusion tube for targeted drug delivery; Splitting needle for suturing operations, with tail cord hole; Splitting needle with removable needle for disposable needle replacement.

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