Artificial joint friction liner compositely molded by polyethylene and preparation method of artificial joint friction liner

Abstract

The invention relates to the technical field of artificial joint prostheses, in particular to a polyethylene composite molded artificial joint friction liner and a preparation method thereof, and the method comprises the following steps: firstly, respectively manufacturing a high-crosslinking blank and a non-crosslinking blank, and enabling the high-crosslinking blank and the non-crosslinking blank to have matched contact interfaces; then putting the two parts into a mold consisting of an inner mold and an outer mold according to a position relationship, and ensuring that all contact surfaces are matched and butted; then carrying out mold pressing treatment, firstly applying initial pressure at low temperature, then heating to 150-250 DEG C and boosting to 10-20 MPa for hot-pressing compounding, so that a non-crosslinking part is molten and is integrated with a high-crosslinking part at an interface; and finally, cooling, demolding and machining to obtain a finished product. The friction surface of the prepared friction liner is made of a high-crosslinking material, the friction liner is endowed with excellent wear resistance, the base body of the friction liner is made of a non-crosslinking material, excellent mechanical strength and toughness are provided, and the technical problem that wear resistance and impact resistance of an artificial joint are difficult to consider at the same time is perfectly solved.

Description

Technical Field

[0001] This invention relates to the field of artificial joint prosthesis technology, specifically to a polyethylene composite molded artificial joint friction pad and its preparation method. Background Technology

[0002] The long-term safety and effectiveness of artificial joints depend on the wear resistance, aging resistance, mechanical strength, and toughness of their friction pairs, particularly ultra-high molecular weight polyethylene (UHMWPE). Since the late 1990s, highly cross-linked UHMWPE has been widely used in the field of artificial joints, especially artificial hip joints, due to its excellent wear resistance. Highly cross-linked UHMWPE is typically treated by irradiating ordinary non-cross-linked UHMWPE profiles with high-energy radiation (such as ray, electron beam, or X-ray) at doses exceeding 40 kGy, followed by heat treatment (such as remelting or annealing) to stabilize the material.

[0003] While highly cross-linked ultra-high molecular weight polyethylene (UHMWPE) possesses superior wear resistance and oxidation resistance, its mechanical properties, particularly impact strength and toughness, are significantly lower than those of non-cross-linked UHMWPE. Higher cross-linking levels result in higher wear resistance, but also a greater reduction in impact strength and toughness. To address the conflict between wear resistance and impact strength / toughness in highly cross-linked UHMWPE friction pads, researchers have proposed the concept of surface cross-linking or selective local cross-linking of UHMWPE friction pads to meet the requirements of high wear resistance on the pad's friction surface while maintaining overall impact strength and toughness. US Patent 5414049 proposes a method for irradiating the surface of UHMWPE friction pads with a low-energy electron beam, while US Patent 6448315 B1 proposes a method for increasing the cross-linking degree of the pad's friction surface through ultraviolet radiation and optical reactions.

[0004] However, these methods still have limitations such as shallow processing layers and abrupt changes in performance gradients. Therefore, a polyethylene composite molded artificial joint friction pad and its preparation method are provided. Summary of the Invention

[0005] The purpose of this invention is to provide a polyethylene composite molded artificial joint friction pad and its preparation method, so as to solve the problems mentioned in the background art.

[0006] To solve the above-mentioned technical problems, the present invention provides the following technical solution: In a first aspect, the present invention provides a method for preparing a polyethylene composite molded artificial joint friction pad, comprising the following steps: S1. Highly cross-linked blanks are made from highly cross-linked ultra-high molecular weight polyethylene profiles; S2. A non-crosslinked blank with an shape that matches the high-crosslinked blank is made of non-high-crosslinked ultra-high molecular weight polyethylene profile; S3. Place the highly cross-linked blank into the bottom of the cavity of the outer mold, so that its molding surface matches the highly polished surface of the cavity; S4. Place the non-crosslinked blank into the cavity, so that its adapting surface matches the contact interface of the highly crosslinked blank; S5. Assemble the inner mold of the mold into the outer mold, wherein the bottom of the inner mold matches the upper surface of the non-crosslinked blank; S6. Place the assembled mold in the molding machine and apply a pressure of 2-10 MPa when the mold temperature is below 100°C. S7. Under the condition of maintaining pressure, heat the mold to 150°C to 250°C and increase the pressure to 10MPa to 20MPa, and keep it at the temperature and pressure for 1 to 10 hours, so that the highly cross-linked blank and the non-cross-linked blank are compositely formed at the interface to obtain a composite preform. S8. Demold the mold after cooling it to below 40°C while maintaining pressure. S9. The composite preform is machined to form a friction pad, and the surface integrity of the highly polished friction surface of the friction pad is maintained.

[0007] Preferably, the thickness of the highly cross-linked preform is 1 mm to 3 mm.

[0008] Preferably, the highly cross-linked blank in step S1 is machined from a highly cross-linked ultra-high molecular weight polyethylene profile that has been irradiated with high-energy rays with a radiation dose greater than 40 kGy and then heat-treated.

[0009] Preferably, the heat treatment is a remelting treatment above the material's melting point or an annealing treatment below the material's melting point.

[0010] Preferably, the radiation dose is between 50 and 100 kGy.

[0011] Preferably, the highly cross-linked ultra-high molecular weight polyethylene profile and / or the non-highly cross-linked ultra-high molecular weight polyethylene profile may optionally contain an antioxidant.

[0012] Secondly, the present invention provides a polyethylene composite molding artificial joint friction pad prepared by any of the above preparation methods.

[0013] Preferably, the artificial joint friction pad is a hip joint acetabular cup friction pad, a knee joint tibial friction pad, or a shoulder joint friction pad.

[0014] Compared with the prior art, the beneficial effects achieved by the present invention are: 1. Optimal performance combination: By directly compounding highly cross-linked ultra-high molecular weight polyethylene (UHMWPE) profiles (high wear resistance) and non-highly cross-linked UHMWPE profiles (high mechanical strength) in a mold, the optimal performance configuration of different areas on a single component is achieved, perfectly resolving the conflict between wear resistance and toughness. 2. Strong interface bonding: Through the “fitting and mating” interface design and the molding process under specific temperature and pressure, the two materials form a strong whole at the interface through molecular chain diffusion and entanglement, avoiding the risk of delamination; 3. Reliable process: The molding process used is mature and stable. By precisely controlling the initial pressurization, heating and pressurization, pressure holding and cooling processes, the consistency and reliability of the products are ensured. 4. Wide range of applications: This method is applicable to the preparation of friction pads for various artificial joints such as hip, knee, and shoulder, and has wide applicability. Attached Figure Description

[0015] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used in conjunction with embodiments of the invention to explain the invention and do not constitute a limitation thereof. In the drawings: Figure 1 This is a schematic diagram of the highly cross-linked preform in this invention.

[0016] Figure 2 This is a schematic diagram of the non-crosslinked embryo in this invention.

[0017] Figure 3 This is a schematic diagram of the combination of highly cross-linked blanks, non-cross-linked blanks, and molds in this invention.

[0018] Figure 4 This is a schematic diagram showing the mold fully closed after the upper inner mold is assembled in this invention.

[0019] Figure 5 This is a schematic diagram of the composite preform obtained after compression molding according to the present invention.

[0020] Figure 6 This is a schematic diagram of the friction pad finally obtained after machining according to the present invention. Detailed Implementation

[0021] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] Please see Figure 1-6The present invention provides a technical solution: a method for preparing a polyethylene composite molded artificial joint friction pad, comprising the following steps: S1. Using highly cross-linked ultra-high molecular weight polyethylene profiles, such as sheets or rods, as the base material, a highly cross-linked blank with a thickness between 1 mm and 3 mm is manufactured according to the design requirements of machining and padding friction surfaces; the highly cross-linked ultra-high molecular weight polyethylene profile is a material that has been irradiated by high-energy rays and heat-treated, with a radiation dose greater than 40 kGy, generally between 50 and 100 kGy, and the heat treatment is either a remelting treatment above the material's melting point or an annealing treatment below the material's melting point; S2. A non-crosslinked blank with an shape that matches the high-crosslinked blank is made of non-high-crosslinked ultra-high molecular weight polyethylene profile; Highly cross-linked ultra-high molecular weight polyethylene profiles and / or non-highly cross-linked ultra-high molecular weight polyethylene profiles may optionally contain antioxidants such as vitamin E5; S3. Place the highly cross-linked blank into the bottom of the cavity of the outer mold, so that its molding surface matches the highly polished surface of the cavity; S4. Place the non-crosslinked blank into the cavity so that its adapting surface matches the contact interface of the highly crosslinked blank. S5. Assemble the inner mold into the outer mold, with the bottom of the inner mold matching the upper surface of the non-crosslinked blank. S6. Place the assembled mold in the molding machine and apply a pressure of 2-10 MPa when the mold temperature is below 100°C. S7. While maintaining pressure, heat the mold to 150°C to 250°C, generally between 180-250°C, and increase the pressure to 10MPa to 20MPa. Maintain the temperature and pressure for 1 to 10 hours, generally between 2-6 hours, so that the highly cross-linked blank and the non-cross-linked blank are compositely formed at the interface to obtain a composite preform. S8. After cooling the mold to room temperature (40°C) or below under pressure, demold the mold. The cooling time is generally between 1 and 5 hours. S9. Machining the composite preform to make a friction pad, and maintaining the surface integrity of the high-polished friction surface of the friction pad, without damaging the high-polished friction surface of the friction pad.

[0023] An artificial joint friction pad made of polyethylene composite by the above preparation method is a hip joint acetabular cup friction pad, a knee joint tibial friction pad, or a shoulder joint friction pad.

[0024] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of making a polyethylene composite molded artificial joint friction liner, characterized by, The method comprises the following steps: S1, making a high crosslinking blank from a high crosslinking UHMWPE profile; S2, making a non-crosslinking blank with an outer shape matching that of the high crosslinking blank from a non-high crosslinking UHMWPE profile; S3, placing the high crosslinking blank into the bottom of the cavity of the outer mold of the mold, so that the molding surface of the high crosslinking blank matches the highly polished surface of the cavity; S4, placing the non-crosslinking blank into the cavity, so that the mating surface of the non-crosslinking blank matches the contact interface of the high crosslinking blank; S5, assembling the upper inner mold of the mold into the outer mold, so that the bottom of the upper inner mold matches the upper surface of the non-crosslinking blank; S6, placing the assembled mold into a molding machine, and applying a pressure of 2-10 MPa at a mold temperature below 100°C; S7, heating the mold to 150°C-250°C while maintaining the pressure, and increasing the pressure to 10-20 MPa, and keeping the temperature and pressure for 1-10 hours, so that the high crosslinking blank and the non-crosslinking blank are compounded at the interface to obtain a compound preform; S8, demolding after cooling the mold to below 40°C under pressure; S9, machining the compound preform to make a friction pad, and keeping the surface integrity of the highly polished friction surface of the friction pad.

2. A method of making a polyethylene composite molded artificial joint friction liner according to claim 1, characterized in that, The thickness of the high crosslinking blank is 1-3 mm.

3. A method of making a polyethylene composite molded artificial joint friction liner according to claim 1, characterized in that, The high crosslinking blank in step S1 is machined from a high crosslinking UHMWPE profile that has been irradiated by high-energy rays at a dose greater than 40 kGy and subjected to heat treatment.

4. A method of making a polyethylene composite molded artificial joint friction liner according to claim 3, characterized in that, The heat treatment is remelting treatment above the melting point of the material or annealing treatment below the melting point of the material.

5. A method of making a polyethylene composite molded artificial joint friction liner according to claim 3, characterized in that: The radiation dose is between 50 and 100 kGy.

6. The method for preparing a polyethylene composite molded artificial joint friction pad according to claim 1, characterized in that, The high crosslinking UHMWPE profile and / or the non-high crosslinking UHMWPE profile optionally contains an antioxidant.

7. A polyethylene composite molded artificial joint friction liner characterized by, Prepared by the method of any one of claims 1-6.

8. A polyethylene composite molded artificial joint friction liner according to claim 7, wherein The artificial joint friction pad is a hip joint cup friction pad, a knee joint tibial friction pad, or a shoulder joint friction pad. The artificial joint friction pad is a hip joint cup friction pad, a knee joint tibial friction pad, or a shoulder joint friction pad.

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