Polypropylene composite material based on rare earth element modification and preparation method and application thereof

Abstract

The application discloses a kind of polypropylene composite based on rare earth element modification and its preparation method and application, belong to medical instrument technical field, include the following raw materials according to weight parts: 100 parts medical grade PP, 3~8 parts rare earth organic complex, 5~10 parts nano hydroxyapatite, 2~5 parts maleic anhydride grafted PP compatilizer and 0.3~0.5 parts antioxidant, and its specific preparation steps and application are provided.The application adopts "oxide+salt" bimorph rare earth and organic ligand complex to form rare earth organic complex, solves the problem of poor dispersibility of inorganic rare earth, and simultaneously endows the material with antibacterial and antistatic functions;Subsequently, by melt blending-in situ fiber forming process, the rare earth complex forms a gradient distribution in the polypropylene matrix, the surface layer is rich in antibacterial components, and the inner layer enhances the mechanical properties, providing a low-cost solution for high-end medical devices with high strength, antibacterial properties and biocompatibility, filling the market gap.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical devices, in particular to a polypropylene composite material based on rare earth element modification and a preparation method and application thereof. BACKGROUND

[0002] Medical devices have extremely strict requirements for the performance of materials. Not only should they have good biocompatibility to prevent triggering human immune responses, but they also need excellent mechanical properties to ensure the reliability and stability of the devices in complex use environments.

[0003] Polypropylene is widely used in the manufacture of medical devices due to its excellent biocompatibility and processing performance. However, traditional polypropylene materials have insufficient antibacterial properties and are prone to bacterial growth on the surface, especially in long-term implantation or high-frequency contact scenarios, which can easily trigger infection risks. They need to rely on chemical sterilizing agents for periodic sterilization, and the residues of chemical sterilizing agents can easily cause performance degradation such as material embrittlement and reduced transparency. Repeated sterilization shortens the service life of the device, increases medical costs, and has the risk of environmental pollution during the chemical sterilization process.

[0004] In the prior art, salts and oxides of rare earth elements such as lanthanum and cerium have been proven to have broad-spectrum antibacterial properties due to their unique photocatalytic activity and biocompatibility. However, directly compounding them with PP can easily lead to uneven dispersion, decreased mechanical properties, and easy aggregation, resulting in unstable modification effects. Therefore, new composite technologies need to be developed.

[0005] Based on the above, a polypropylene composite material based on rare earth element modification and a preparation method and application thereof are proposed. SUMMARY

[0006] The purpose of the present application is to provide a polypropylene composite material based on rare earth element modification and a preparation method and application thereof to solve the problems in the background art.

[0007] To achieve the above-mentioned purpose, the present application provides a polypropylene composite material based on rare earth element modification, which comprises the following raw materials by weight:

[0008] 100 parts of medical grade PP, 3-8 parts of rare earth organic complex, 5-10 parts of nano-hydroxyapatite, 2-5 parts of maleic anhydride grafted PP compatibilizer, 1-2 parts of silane coupling agent, and 0.3-0.5 parts of antioxidant.

[0009] Preferably, the rare earth organic complex is a compound formed by complexing a rare earth compound with an organic ligand.

[0010] Preferably, the rare earth compound is a mixture of several kinds of salts and oxides of lanthanum and cerium, and the organic ligand is a beta-diketone compound.

[0011] Preferably, the beta-diketone compound is one of acetylacetone, benzoylacetone.

[0012] The application provides a preparation method of the polypropylene composite material modified by the rare earth element.

[0013] S1, raw material pretreatment: preparing a rare earth organic complex and performing surface treatment on the nano-hydroxyapatite;

[0014] S2, placing the rare earth organic complex, maleic anhydride grafted PP compatilizer and silane coupling agent in a banbury mixer to perform premixing, and obtaining premixing material;

[0015] S3, jointly adding the premixing material, medical grade PP, the nano-hydroxyapatite subjected to surface treatment and an antioxidant into a double-screw extruder to perform extrusion granulation, and obtaining the polypropylene composite material modified by the rare earth element.

[0016] Preferably, the preparation steps of the rare earth organic complex are as follows:

[0017] 1) pretreatment: placing rare earth salt and rare earth oxide with a ratio of 1:1-3 into a vacuum drying box to dry, and performing distillation on the beta-diketone compound;

[0018] 2) dissolving the rare earth oxide and the rare earth salt after drying in anhydrous ethanol, stirring at a rotating speed of 150-250 rpm, maintaining the temperature of the reaction system at 60-80 DEG C, slowly adding the beta-diketone compound solution through a dropping funnel, controlling the dropping time at 1-2 h, and continuing to stir for 3-5 h after the dropping is completed;

[0019] 3) after the reaction is completed and cooling to room temperature, adding deionized water under stirring to make the rare earth organic complex precipitate, performing suction filtration and washing on the precipitate using a sand core funnel, then placing the washed precipitate in a vacuum drying box to dry at 60-80 DEG C for 10-14 h, and obtaining the rare earth organic complex.

[0020] Preferably, in S2, the temperature of the banbury mixer is controlled at 120-130 DEG C, the rotating speed is 80-120 rpm, and the premixing time is 10-20 min.

[0021] Preferably, in S2, the silane coupling agent is one of KH550 or KH570.

[0022] Preferably, in S3, the temperature of the extruder is controlled as follows: the temperature of the feeding section is 180-185 DEG C, the temperature of the second section is 180-200 DEG C, the temperature of the third section is 190-205 DEG C, the temperature of the fourth section is 200-210 DEG C, and the temperature of the fifth section is 205-220 DEG C, and the rotating speed of the screw is controlled at 280-320 rpm.

[0023] The application also provides the application of the rare earth element modified polypropylene composite material, characterized in that the rare earth element modified polypropylene composite material is applied to medical devices.

[0024] Preferably, nitrogen protection is adopted in the injection molding process of the medical device by using the rare earth element modified polypropylene composite material, and the formed product is irradiated by γ rays with a dose of 5-15 kGy to activate the surface antibacterial activity of the rare earth.

[0025] Therefore, the rare earth element modified polypropylene composite material, the preparation method and the application thereof have the following beneficial effects:

[0026] (1) In the present application, the rare earth-polypropylene composite system is used, medical grade PP is used as the aggregate, and rare earth oxides provide long-acting physical antibacterial effect, and rare earth salts enhance the chemical bacteriostatic effect through ion slow release, and the two synergistically act to reduce the dependence of medical devices on chemical sterilization.

[0027] (2) In the preparation process of the present application, first, the rare earth element is complexed with an organic ligand to form a rare earth organic complex, which solves the problem of poor dispersibility of inorganic rare earth and simultaneously endows the material with antibacterial and antistatic functions; then, through melt blending-in-situ fiber forming process, the rare earth organic complex forms a gradient distribution in the polypropylene matrix, the surface layer is rich in antibacterial components, and the inner layer enhances the mechanical properties; secondly, in the premixing stage, the silane coupling agent can chemically react on the surface of the rare earth complex to form a chemical bond, thereby improving the compatibility and interface bonding performance of the rare earth complex with other materials, and simultaneously, together with the compatibilizer, it can better improve the dispersion uniformity of the rare earth complex in the matrix and improve the comprehensive performance of the material.

[0028] (3) The composite material prepared by the present application is applied to medical devices, and the bacteriostatic rate of common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus is >99% (GB / T31402-2015), which reduces the formation of biofilm on the surface of the device; the cytotoxicity is ≤1 level (ISO 10993-5), which meets the long-term implantation requirements.

[0029] The technical solutions of the present application will be further described in detail through the following examples. DETAILED DESCRIPTION

[0030] The technical solutions of the present application will be further described in detail through the following examples.

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present application more clear, the technical solutions in the embodiments of the present application will be clearly and completely described below, obviously, the described embodiments are part of the embodiments of the present application, but not all the embodiments.

[0032] Example 1

[0033] This embodiment improves the antibacterial performance of the syringe by preparing a rare earth element modified polypropylene composite material and applying it to the production of the syringe. The specific steps are as follows:

[0034] S1, first synthesize a rare earth organic complex, specifically:

[0035] 1) Mix lanthanum oxide, cerium oxide and cerium ammonium citrate in a mass ratio of 1:2:1, then place them in a vacuum drying box and dry at 90°C for 10h to remove crystal water and adsorbed water, obtaining a mixed rare earth compound;

[0036] 2) Dissolve the dried mixed rare earth compound in anhydrous ethanol and transfer it to a three-necked flask equipped with a stirrer, a thermometer and a dropping funnel. Turn on the stirring device and set the stirring speed to 200rpm. At the same time, maintain the temperature of the reaction system at 70°C. Slowly add acetylacetone solution through the dropping funnel. The dropping process lasts for 1.5h. After the dropping is completed, continue to stir for 4h to ensure that the rare earth ions are fully complexed with the organic ligand.

[0037] 3) Cool to room temperature after the reaction is completed. Slowly add deionized water under stirring to precipitate the rare earth organic complex. Use a sand core funnel to filter, wash the precipitate with anhydrous ethanol for 3 times, and then dry it in a vacuum drying box at 70°C for 12h to obtain the rare earth organic complex.

[0038] S2, add 5 parts of the rare earth organic complex prepared in S1, 3 parts of maleic anhydride grafted PP compatibilizer and 1 part of silane coupling agent KH550 to a banbury mixer, and pre-mix at 130°C and 100rpm for 15min to obtain a pre-mixed material.

[0039] S3, take nano-hydroxyapatite, add 3% of stearic acid by mass, and stir in a high-speed mixer at 80°C for 30min to uniformly coat the stearic acid on the surface of the nano-hydroxyapatite, improving its dispersibility in the polypropylene matrix;

[0040] Then add the pre-mixed material, 100 parts of medical grade PP, 6 parts of surface treated nano-hydroxyapatite and 0.3 parts of antioxidant 1010 to a twin-screw extruder. The temperature of the extruder from the feeding section to the die head is set to 180°C, 190°C, 200°C, 210°C and 220°C respectively. The screw speed is 300rpm. Extrude and granulate to obtain a rare earth element modified polypropylene composite material.

[0041] S4, syringe injection molding: the granulated composite material is put into an injection molding machine, the barrel temperature is set to 190-210℃, the mold temperature is set to 30-50℃, the injection pressure is set to 80-120MPa, the pressure holding time is set to 10-20s, and nitrogen is added to assist injection molding, to obtain a syringe product;

[0042] The syringe product is placed in a gamma ray irradiation device, and treated at an irradiation dose of 10kGy to activate the surface antibacterial activity of the rare earth.

[0043] Example 2

[0044] The raw materials are as follows by weight:

[0045] 100 parts of medical grade PP, 3 parts of rare earth organic complex, 2 parts of maleic anhydride grafted PP compatibilizer, 1 part of silane coupling agent KH550, 5 parts of nano hydroxyapatite, and 0.4 parts of antioxidant 1010;

[0046] The raw materials in the synthesis of the rare earth organic complex are lanthanum oxide and cerium chloride in a mass ratio of 1:1; the syringe product is prepared according to the steps in Example 1 with the remaining conditions unchanged.

[0047] Example 3

[0048] The raw materials are as follows by weight:

[0049] 100 parts of medical grade PP, 8 parts of rare earth organic complex, 5 parts of maleic anhydride grafted PP compatibilizer, 2 parts of silane coupling agent KH550, 10 parts of nano hydroxyapatite, and 0.5 parts of antioxidant 1010;

[0050] The raw materials in the synthesis of the rare earth organic complex are lanthanum oxide, lanthanum oxide, and cerium chloride in a mass ratio of 1:1:1; the syringe product is prepared according to the steps in Example 1 with the remaining conditions unchanged.

[0051] Comparative Example 1

[0052] Comparative Example 1 has the same steps as the examples, except that the raw materials in the synthesis of the rare earth organic complex are modified to lanthanum oxide, cerium oxide, and cerium ammonium citrate in a mass ratio of 1:1:4.

[0053] Comparative Example 2

[0054] The steps in Comparative Example 2 are the same as those in Example 2, except that the raw materials in the synthesis of the rare earth organic complex are modified to lanthanum oxide and cerium chloride in a mass ratio of 4:1.

[0055] Comparative Example 3

[0056] The steps in Comparative Example 3 are the same as those in Example 1, except that the final gamma ray irradiation operation is removed.

[0057] Comparative Example 4

[0058] The present comparative example is the same as the steps in Example 1, except that the irradiation dose of the final gamma irradiation operation is modified to 30 kGy.

[0059] Comparative Example 5

[0060] The present comparative example is the same as the steps in Example 1, except that the temperature of the extruder from the feeding section to the head is modified to 150℃, 160℃, 170℃, 180℃, 190℃, respectively, and the screw speed is 200 rpm.

[0061] Comparative Example 6

[0062] The present comparative example is the same as the steps in Example 1, except that the temperature of the extruder from the feeding section to the head is modified to 200℃, 210℃, 220℃, 230℃, 240℃, respectively, and the speed is 450 rpm.

[0063] The products of the above examples and comparative examples are subjected to antibacterial testing, and the antibacterial rate results are shown in Table 1 below:

[0064] Table 1 Antibacterial rate results

[0065] Sample Escherichia coli inhibition rate Staphylococcus aureus inhibition rate Example 1 99.6％ 99.8％ Example 2 99.3％ 99.6％ Example 3 99.5％ 99.2％ Comparative Example 1 85.6％ 83.2％ Comparative Example 2 88.4％ 86.2％ Comparative Example 3 92.3％ 93.4％ Comparative Example 4 89.3％ 88.9％ Comparative Example 5 95.3％ 95.6％ Comparative Example 6 97.1％ 97.4％

[0066] As can be seen from Table 1 above, when preparing rare earth organic ligands, the mass ratio of rare earth salt to rare earth oxide in Examples 1-3 is controlled in the range of 1:1-3, and the antibacterial performance of the injection molded products obtained is better. When the ratio exceeds this range, such as Comparative Examples 1 and 2, the antibacterial performance decreases, indicating that the products prepared by the protected scheme of the present application have a 24-hour antibacterial rate of ≥99% for common pathogenic bacteria such as Escherichia coli and Staphylococcus aureus, can reduce the formation of biofilm on the surface of instruments, and meet the antibacterial performance requirements of medical syringes.

[0067] By comparing Example 1 with Comparative Examples 3 and 4, the antibacterial rate of Comparative Example 3 is lower than that of Example 1 because it does not undergo a gamma irradiation operation. This is because the gamma irradiation activates the antibacterial activity on the surface of rare earth, which enhances the antibacterial performance. In Comparative Example 4, the irradiation dose is too large, which causes excessive damage to the material performance and antibacterial components, resulting in a decrease in the antibacterial rate.

[0068] By comparing Example 1, Comparative Example 5 and Comparative Example 6, the temperature of the temperature control zone of the extruder in Comparative Example 5 is lower than that in Example 1, and the rotation speed is reduced, and the final antibacterial rate is reduced. The reason is that too low temperature can cause poor melting effect of polypropylene resin, rare earth organic complex, nano-hydroxyapatite and other raw materials, and the dispersion of antibacterial agent can also be uneven, resulting in reduced antibacterial performance. In Comparative Example 6, the temperature of the temperature control zone of the extruder is higher than that in Example 1, and the final antibacterial rate is reduced. This is because too high temperature can also affect the stability of the rare earth organic complex, and then affect the antibacterial performance and biocompatibility, etc.

[0069] The mechanical properties of Examples 1-3, Comparative Examples 5 and 6 described above were tested, pure PP was used as a control group, and the tensile strength was tested according to ASTM D638 standard, and the bending modulus was tested according to ASTM D790 standard. The results are shown in Table 2 below.

[0070] Table 2: Mechanical property test results

[0071]

[0072]

[0073] As can be seen from Table 2, compared with pure PP, the tensile strength of the product prepared by the present application is increased by more than 35%, and the bending modulus is increased by more than 40%. In Comparative Example 5, the temperature of the temperature control zone of the extruder is lower than that in Example 1, and the tensile strength and bending modulus are also relatively reduced. The reason is that too low temperature can cause poor melting effect of polypropylene resin, rare earth organic complex, nano-hydroxyapatite and other raw materials, and the mixture is not uniform, thereby reducing the mechanical properties of the material. In Comparative Example 6, the temperature of the temperature control zone of the extruder is higher than that in Example 1, and the tensile strength and bending modulus are also relatively reduced. This is because too high temperature and rotation speed can cause degradation of polypropylene resin, resulting in poor mechanical properties of the material. Moreover, too high rotation speed can cause nano-hydroxyapatite and other particles to be too uniformly distributed in the material, which is not conducive to forming an effective reinforcing structure, and also affects the mechanical properties.

[0074] It can be seen from the comparison that in the temperature control zone of the extruder, the temperature from the feeding section to the head is set to 180-185°C, 180-200°C, 190-205°C, 200-210°C, and 205-220°C, i.e. the temperature in the temperature control zone of the extruder is set to 180-220°C. This temperature range can make the polymer matrix in the system reach a suitable viscous flow state. In this state, the activity of the polymer molecular chain is enhanced, which is beneficial to the orientation and arrangement of the molecular chain. For in-situ fiber formation, at a specific temperature, the dispersed phase is stretched into a fibrous shape under the action of the flow field of the continuous phase. The temperature ensures that the dispersed phase has sufficient fluidity to deform and form a fiber structure. By forming a temperature gradient through different temperature control zones, the temperature difference will cause the physical state and the degree of molecular chain movement in different regions to be different. For example, in the region with higher temperature, the activity of the molecular chain is stronger, and the dispersed phase is more easily stretched into a fiber; while in the region with lower temperature, the movement of the molecular chain is relatively limited, which is beneficial to fixing the fiber structure and microstructure that has been formed, thereby forming a gradient structure.

[0075] Meanwhile, the screw rotation speed in the examples is set to 300 rpm, and higher rotation speed will generate strong shearing force and stretching force. Under the action of the shearing force, the dispersed phase particles are continuously stretched and refined, which promotes the formation of fibrous structure and realizes in-situ fiber formation. At the same time, the rotation of the screw forms a complex flow field in the extruder, and the degree of shearing and stretching action on the materials at different positions is different, thereby making the rare earth organic complex form a gradient distribution in the polypropylene aggregate.

[0076] The cytotoxicity test of the products of the above examples 1-3 was carried out according to the ISO 10993-5 standard, and the cytotoxicity rating of all groups was ≤1, indicating good biocompatibility and meeting the long-term implantation requirements.

[0077] The syringe in example 1 was tested. Under the conventional use environment, the instrument can withstand ≥5 wet heat sterilization cycles (121°C / 30min) without losing mechanical properties; compared with the unmodified polypropylene instrument, the service life is increased by 2-3 times (verified by ISO 10993 biocompatibility test), the single medical process instrument loss cost is reduced by 40-60%, and the purchase and processing cost of chemical sterilizing agents is avoided.

[0078] The above examples show that when the composite material is applied to a disposable syringe, it has excellent performance, such as good biocompatibility, chemical stability and excellent mechanical properties, so in some examples, it can also be used in infusion devices, medical packaging materials and various pipeline connectors in operating rooms.

[0079] The medical grade PP and the rare earth organic complex have good biocompatibility, and can reduce stimulation and adverse reactions to human tissues; the nano-hydroxyapatite is similar to the main component of human bone and teeth, has excellent biological activity and compatibility, and can reduce the risk of immune response caused by the material in the body; the rare earth organic complex helps to improve the affinity of the overall material to biological tissues. At the same time, the medical grade PP provides basic strength and toughness, so that the composite material can withstand certain external force without deformation or rupture; the addition of nano-hydroxyapatite can enhance the hardness and rigidity of the composite material, improve its wear resistance, and make it more suitable for use in operating room pipeline connectors and the like which need to bear certain pressure and friction. The maleic anhydride grafted PP compatibilizer improves the interface bonding between different components, so that the mechanical properties of the composite material are more stable and uniform, and damage caused by stress concentration is reduced.

[0080] In addition, the medical grade PP and the maleic anhydride grafted PP have good chemical stability, can resist the erosion of infusion drugs, disinfectants and the like, and are not prone to chemical reactions that affect the performance of the material and the quality of the drug. The addition of the antioxidant can effectively inhibit the oxidation reaction of the composite material during use, slow down the aging rate of the material, and prolong its service life, which is very important for long-term use of operating room pipeline connectors and drug packaging materials and infusion devices that may be stored for a long time, and can ensure the stable performance of the material within the effective period.

[0081] The rare earth organic complex can endow the composite material with some special functions, such as fluorescence, which can be used for marking, tracking and monitoring of drug packaging materials or infusion processes, and helps to improve the safety and traceability of the medical process.

[0082] Therefore, the polypropylene composite material based on rare earth element modification and its preparation method and application adopt the rare earth organic complex synthesized by complexing the "oxide + salt" dual-form rare earth with an organic ligand, solve the problem of poor dispersibility of inorganic rare earth, and endow the material with antibacterial and antistatic functions; subsequently, the rare earth complex is formed in a gradient distribution in the polypropylene matrix through a melt blending-in-situ fiber forming process, the antibacterial component is enriched on the surface layer, and the mechanical properties are enhanced in the inner layer, which provides a low-cost solution for high-end medical devices with high strength, antibacterial property and biocompatibility, and fills the market gap.

[0083] Finally, it should be noted that: the above examples are only used to illustrate the technical solutions of the present application but not to limit it, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can still be modified or replaced by equivalents, and these modifications or equivalent replacements cannot make the modified technical solutions deviate from the spirit and scope of the technical solutions of the present application.

Claims

1. A polypropylene composite material based on rare earth element modification, characterized in that, The following ingredients are included by weight: 100 parts medical-grade PP, 3-8 parts rare earth organic complex, 5-10 parts nano hydroxyapatite, 2-5 parts maleic anhydride-grafted PP compatibilizer, 1-2 parts silane coupling agent and 0.3-0.5 parts antioxidant; The rare earth organic complex is a compound formed by the complexation of a rare earth compound and an organic ligand. The rare earth compound is a mixture of several salts and oxides of lanthanum and salts and oxides of cerium, and the organic ligand is... β -Diketone compounds; The preparation steps for rare earth organic complexes are as follows: 1) Pretreatment: Place rare earth salts and rare earth oxides in a vacuum drying oven at a ratio of 1:1~3 for drying, while simultaneously... β - Diketone compounds are distilled; 2) Dissolve the dried rare earth oxides and rare earth salts in anhydrous ethanol, stir at 150-250 rpm, maintain the reaction system temperature at 60-80℃, and slowly add the solutions dropwise through a dropping funnel. β - For diketone compounds, the dropping time is controlled at 1~2 hours. After the dropping is completed, the reaction is stirred for 3~5 hours. 3) After the reaction is completed and cooled to room temperature, deionized water is added dropwise under stirring to precipitate the rare earth organic complex. The precipitate is filtered and washed using a sintered sand funnel. The washed precipitate is then placed in a vacuum drying oven and dried at 60-80℃ for 10-14 hours to obtain the rare earth organic complex. The preparation method of polypropylene composite material modified by rare earth elements includes the following steps: S1. Raw material pretreatment: Prepare rare earth organic complexes and perform surface treatment on nano-hydroxyapatite; S2. Place the rare earth organic complex, maleic anhydride-grafted PP compatibilizer, and silane coupling agent in a mixer and premix them to obtain a premixed material. S3. The premixed material, medical-grade PP, surface-treated nano-hydroxyapatite, and antioxidant are added together into a twin-screw extruder for extrusion granulation to obtain rare earth element modified polypropylene composite particles. In the temperature control zone of the extruder, the temperature from the feeding section to the die head is set to 170~190℃, 180~200℃, 190~210℃, 200~220℃, and 210~230℃ respectively, and the screw speed is controlled at 280~320rpm. Nitrogen protection was used during the injection molding of medical devices using rare-earth element-modified polypropylene composite materials. After molding, [the process was followed by...]. Radiation irradiation at a dose of 5-15 kGy activates the antibacterial activity of rare earth surfaces.

2. The polypropylene composite material based on rare earth element modification according to claim 1, characterized in that: In S2, the internal mixer temperature is controlled at 120~130℃, the rotation speed is 80~120rpm, and the premixing time is 10~20min.

3. The polypropylene composite material based on rare earth element modification according to claim 1, characterized in that: In S2, the silane coupling agent is either KH550 or KH570.

4. The application of a polypropylene composite material based on rare earth element modification as described in any one of claims 1-3, characterized in that: Rare earth element modified polypropylene composites are used in medical devices.

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