Medical-grade polypropylene-propylene-butylene copolymer composition as well as preparation method and application thereof

Abstract

The invention discloses a medical-grade polypropylene-propylene-butylene copolymer composition as well as a preparation method and application of the medical-grade polypropylene-propylene-butylene copolymer composition. The polypropylene composition is prepared from the following raw materials in parts by mass: 100 parts of propylene-butadiene binary co-polypropylene, 0.1-0.5 part of an antibacterial agent, 0.1-0.3 part of a main antioxidant, 0.1-0.2 part of an auxiliary antioxidant, 0.05-0.1 part of a heat-resistant stabilizer, 0.05-0.3 part of an auxiliary aid and 0.2-0.6 part of a transparent nucleating agent. By adopting a combination mode of a supported nano antibacterial agent, a main antioxidant, an auxiliary antioxidant, a heat-resistant stabilizer, an auxiliary aid, a transparent nucleating agent and a compound agent formula thereof, the prepared polypropylene composition has the antibacterial rate of more than or equal to 99% and the mechanical property retention rate of more than or equal to 85% after 10 times of sterilization, and also has excellent mechanical properties and transparency; the precipitate content of the auxiliary agent is less than or equal to 0.1%, so that the auxiliary agent meets the USP Class VI medical standard and has no toxic risk.

Description

Technical Field

[0001] This invention belongs to the field of polymer technology, and particularly relates to a medical-grade propylene-butyl copolymer polypropylene composition, its preparation method and application. Background Technology

[0002] In the field of medical devices, the performance requirements for polymer materials are extremely stringent, especially in scenarios requiring repeated use or prolonged contact with bodily fluids. Materials must not only possess excellent initial mechanical properties and high transparency to meet clinical observation needs, but also have long-lasting antibacterial capabilities to inhibit the growth of pathogenic bacteria, reduce the risk of cross-infection, and withstand multiple high-temperature steam sterilizations without significant performance degradation, thus ensuring the reliability and lifespan of the devices.

[0003] Polypropylene-butadiene copolymer (PPBC) has become an important medical material to replace traditional materials due to its good transparency, impact resistance, and processing flowability. However, existing PPBCs suffer from insufficient antibacterial properties, poor resistance to steam sterilization and aging, and difficulty in maintaining basic properties in practical applications. Pathogenic bacteria easily grow on the material surface, making it difficult to achieve the long-term antibacterial rate of ≥99% required in medical scenarios, especially when reused or in contact with bodily fluids, increasing the risk of infection. After ≥10 standard steam sterilization cycles, the key mechanical properties (such as tensile yield stress and impact strength) of existing materials decrease significantly, often exceeding 20%, failing to meet the long-term stability requirements of reusable devices.

[0004] While adding organic antibacterial agents can improve antibacterial properties in conventional industry solutions, their poor heat resistance makes them prone to decomposition and inactivation under steam sterilization conditions, and they also pose a risk of migration and toxicity, failing to meet medical safety standards. Increasing the amount of traditional antioxidants can improve heat and oxygen aging resistance, but it easily leads to excessive precipitation of the additives, causing "blooming," which also violates medical safety standards. When introducing both antibacterial and antioxidant agents to achieve dual functionality, chemical incompatibility has been found. For example, nano-silver antibacterial agents catalyze the decomposition of antioxidants, resulting in a significant decrease in the efficacy of both. Antibacterial agent aggregation leads to increased material haze, while excessive antioxidant addition can also impair the material's core mechanical properties such as rigidity. Summary of the Invention

[0005] To overcome the above problems, the present invention provides a medical-grade propylene-butyl copolymer polypropylene composition, its preparation method and application, which has both high-efficiency antibacterial properties and resistance to repeated steam sterilization and aging, and also meets medical safety standards, making it suitable for the field of high-end medical devices.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, a medical-grade propylene-butyl copolymer polypropylene composition is prepared from the following raw materials in parts by weight: 100 parts of propylene-butylene copolymer polypropylene; Inorganic antibacterial agent: 0.1-0.5 parts; Main antioxidant: 0.1-0.3 parts; Antioxidant supplement: 0.1-0.2 parts; Heat stabilizer: 0.05-0.1 parts; Auxiliary agents: 0.05-0.3 parts; Transparent nucleating agent: 0.2-0.6 parts.

[0007] The formulation of the composition in this invention is based on the precise control of the molecular chain structure of propylene-butadiene copolymer polypropylene (PPBC). The content of inorganic antibacterial agent affects the antibacterial rate, haze, and flexural modulus. If the amount of inorganic antibacterial agent added is less than 0.1 parts, the antibacterial rate drops sharply and cannot meet the requirements of medical scenarios. If the amount of inorganic antibacterial agent added exceeds 0.5 parts, the nanoparticles agglomerate due to excessively high surface energy, resulting in increased haze and decreased flexural modulus. In addition, the supported carrier antibacterial agent (montmorillonite / zeolite) can alleviate agglomeration through interlayer confinement effect, but if it exceeds 0.5 parts, the stacking of the carrier itself will still destroy the mechanical continuity of the material. The antioxidant system of this invention includes a primary antioxidant and a secondary antioxidant. If the amount of the primary antioxidant added exceeds 0.3 parts, it will lead to an increase in the content of precipitates, which violates the medical safety standards. If the secondary antioxidant is not added, the hydroperoxide may not decompose completely, and the impact retention rate may not be ideal.

[0008] The content of the heat stabilizer in this invention affects the flexural modulus, haze, and exudate content. If the content of the heat stabilizer exceeds 0.1 parts, it will lead to an increase in the exudate content, resulting in increased haze and a decrease in flexural modulus. If no heat stabilizer is added, the resistance to repeated steam sterilization and aging is extremely unsatisfactory.

[0009] The amount of transparent nucleating agent added in this invention is precisely matched with that of the propylene-butadiene binary copolymer polypropylene, which can induce the formation of uniform β-crystals of 2-5 μm, with haze stabilizing at 7-8%. If the amount of transparent nucleating agent added is less than 0.2 parts, the crystal particles become coarse to 10-15 μm, and the haze increases. If the amount of transparent nucleating agent added exceeds 0.6 parts, the nucleating agent agglomerates, leading to a decrease in light transmittance.

[0010] In one or more embodiments, the inorganic antibacterial agent is selected from at least one or more of nano-silver supported antibacterial agents, nano-zinc oxide, and nano-copper oxide; The inorganic antibacterial agent is preferably a nano-silver supported antibacterial agent, and the carrier of the nano-silver supported antibacterial agent is montmorillonite or zeolite.

[0011] In one or more embodiments, the primary antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, or octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

[0012] In one or more embodiments, the auxiliary antioxidant is tris(2,4-di-tert-butylphenyl) phosphite or bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite.

[0013] In one or more embodiments, the heat stabilizer is dodecyl thiodipropionate or a hindered amine light stabilizer. The hindered amine light stabilizer is UV-770.

[0014] In one or more embodiments, the auxiliary agent is calcium stearate or zinc stearate.

[0015] In one or more embodiments, the transparent nucleating agent is nucleating agent NX8000 or a sorbitol-based transparent nucleating agent; The sorbitol-based transparent nucleating agent is selected from one or more of unmodified sorbitol nucleating agents and modified sorbitol nucleating agents; preferably, it is a modified sorbitol nucleating agent. The unmodified sorbitol nucleating agent is dibenzylidene sorbitol (DBS), and the modified sorbitol nucleating agent is poly(1,3:2,4-di(3,4-dimethyl)benzyl sorbitol (NHS-9999).

[0016] In a second aspect, the present invention also provides a method for preparing the medical-grade propylene-butyl copolymer polypropylene composition described above, comprising the following steps: (1) Place each raw material component in a high-speed mixer according to the formula and stir for 5-10 minutes at a speed of 1000-1500 r / min; (2) Add the mixture from step (1) to a twin-screw extruder, melt-blend, extrude and granulate. The extrusion temperature is 180-210℃ and the screw speed is 100-200r / min to achieve melt dispersion. (3) After the mixture is cooled in a water tank, it is granulated by a pelletizer to obtain a medical grade propylene-butadiene copolymer polypropylene composition.

[0017] In one or more embodiments, in step (2), the extrusion temperature zone 1 is 180-190℃, the extrusion temperature zone 2 is 190-200℃, and the extrusion temperature zone 3 is 200-210℃.

[0018] In a third aspect, the present invention also provides the application of the medical-grade propylene-butyl copolymer polypropylene composition described above in medical devices.

[0019] Compared with the prior art, the beneficial effects of the present invention are: This invention employs a combination of a supported nano-antibacterial agent, a primary antioxidant, a secondary antioxidant, a heat-resistant stabilizer, auxiliary additives, a transparent nucleating agent, and its compounding agents. Through the synergistic effect of the antibacterial components, anti-aging components, and auxiliary additives, the antibacterial agent and anti-aging components form a protective network. The carrier of the antibacterial agent blocks the migration of the auxiliary additives, and its ions work in conjunction with the antioxidant to scavenge free radicals. The anti-aging components protect the antibacterial agent from high-temperature oxidation, resulting in longer-lasting antibacterial and anti-aging effects. The auxiliary additives act as harmonizers, neutralizing acidic substances to prevent antioxidant deactivation and reducing interfacial tension to promote the interaction of all components. Uniform dispersion reduces frictional loss during processing, improves compatibility, and achieves a balance between antibacterial properties, aging resistance, and basic performance. It achieves an antibacterial rate of ≥99% and a mechanical property retention rate of ≥85% after 10 sterilization cycles. The addition of inorganic antibacterial agents enhances antibacterial performance. The anti-aging component is a ternary compound consisting of a main antioxidant, a secondary antioxidant, and a heat stabilizer. The main antioxidant captures free radicals, the secondary antioxidant decomposes hydrogen peroxide, and the heat stabilizer enhances high-temperature stability. The auxiliary agents neutralize acidic residues, preventing chemical interference between the antibacterial and antioxidant agents. Nucleating agents guide the orderly arrangement of the auxiliary agents, ensuring both mechanical properties and light transmittance. Detailed Implementation

[0020] In this invention, unless otherwise specified, all other test materials and instruments are conventional test materials in the field and can be purchased through commercial channels.

[0021] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0022] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0023] Example 1 100 parts of propylene-butadiene copolymer polypropylene, 0.2 parts of zeolite-supported nano-silver antibacterial agent, 0.2 parts of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] (antioxidant 1010), 0.15 parts of tris(2,4-di-tert-butylphenyl) phosphite (antioxidant 168), 0.06 parts of dodecyl thiodipropionate (DLTP), 0.15 parts of calcium stearate, and 0.3 parts of transparent nucleating agent NX8000 were placed in a high-speed mixer and stirred at 1200 rpm for 7 min. Subsequently, the mixture was melt-granulated in a twin-screw extruder at zone I 185℃, zone II 195℃, and zone III 205℃, with a screw speed of 150 rpm. After cooling in a water bath, the mixture was granulated by a pelletizer to obtain a medical-grade propylene-butadiene copolymer polypropylene composition.

[0024] Performance testing: 99.7% antibacterial rate against Escherichia coli; after 10 cycles of steam sterilization at 121℃, the tensile yield stress retention rate was 89%, the impact strength retention rate was 87%, the haze was 7.5%, the flexural modulus was 1220MPa, and the exudate content was 0.08% (compliant with USP Class VI standards).

[0025] Example 2 100 parts of propylene-butyl copolymer polypropylene, 0.3 parts of nano zinc oxide antibacterial agent, 0.18 parts of 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene (antioxidant 1330), 0.12 parts of bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite (antioxidant 626), 0.05 parts of light stabilizer UV-770, 0.2 parts of zinc stearate, and 0.4 parts of nucleating agent NHS-9999 were placed in a high-speed mixer and stirred at 1400 rpm for 6 min. Subsequently, the mixture was melt-granulated in a twin-screw extruder at 180°C in zone one, 190°C in zone two, and 200°C in zone three, with a screw speed of 180 rpm. After cooling in a water bath, the mixture was granulated by a pelletizer to obtain a medical-grade propylene-butyl copolymer polypropylene composition.

[0026] Performance testing: 99.8% antibacterial rate against Staphylococcus aureus; 88% tensile yield stress retention rate and 85% impact strength retention rate after 10 sterilization cycles; 7.8% haze; 1200MPa flexural modulus; all indicators meet the requirements for medical-grade materials.

[0027] Example 3 This embodiment is the same as Embodiment 1, except that the antibacterial agent is replaced with nano zinc oxide.

[0028] Example 4 This embodiment is the same as Embodiment 1, except that the antibacterial agent is replaced with nano copper oxide.

[0029] Comparative Example 1 This comparative example is the same as Example 1, except that no inorganic antibacterial agent is added.

[0030] Comparative Example 2 This comparative example is the same as Example 1, except that the antibacterial agent is replaced with an organosilicon quaternary ammonium salt antibacterial agent.

[0031] Comparative Example 3 This comparative example is the same as Example 1, except that no inorganic antibacterial agent or nucleating agent is added.

[0032] Comparative Example 4 This comparative example is the same as Example 1, except that no heat stabilizer is added.

[0033] Comparative Example 5 This comparative example is the same as Example 1, except that no auxiliary antioxidant is added.

[0034] Comparative Example 6 This comparative example is the same as Example 1, except that no auxiliary agents are added.

[0035] Comparative Example 7 This comparative example is the same as Example 1, except that no nucleating agent is added.

[0036] Comparative Example 8 This comparative example is the same as Example 1, except that the amount of antioxidant 1010 added is 0.6 parts.

[0037] Comparative Example 9 This comparative example is the same as Example 1, except that the amount of zeolite-supported nano-silver antibacterial agent added is 1 part.

[0038] Comparative Example 10 This comparative example is the same as Example 1, except that the amount of DLTP added is 0.3 parts.

[0039] Performance testing (1) Testing standards: The antibacterial rate against *Escherichia coli* or *Staphylococcus aureus* was tested according to GB / T31402-2015; the tensile yield stress retention rate after 10 sterilization cycles was tested according to GB / T1040.2-2022; the impact strength retention rate was tested according to GB / T1043.1-2008; the flexural modulus was tested according to GB / T9341-2008; the haze was tested according to GB / T2410; and the exudate content was tested according to USP Class VI (United States Pharmacopeia Class VI medical plastics standard). The experimental results for each sample are shown in Table 1.

[0040] Table 1 shows the measured properties of the propylene-butadiene copolymer polypropylene composition.

[0041] The haze test conditions were: 1 mm, 200℃.

[0042] As shown in Table 1, by using a combination of supported nano-antibacterial agents, primary antioxidants, secondary antioxidants, heat stabilizers, auxiliary additives, and transparent nucleating agents and their compounding agents, and utilizing the synergistic effect of each component, the resulting propylene-butyl copolymer polypropylene composition simultaneously achieves an antibacterial rate of ≥99% and a mechanical property retention rate of ≥85% after 10 sterilization cycles. It also exhibits excellent impact resistance, with a flexural modulus reaching over 1200 MPa, demonstrating excellent mechanical properties. Furthermore, it displays highly transparent optical properties, with an additive exudate content of ≤0.1%, meeting USP Class VI medical standards and posing no toxicity risk.

[0043] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A medical-grade propylene-butyl copolymer polypropylene composition, characterized in that, It is prepared from the following parts by weight of raw materials: 100 parts of propylene-butylene copolymer polypropylene; Inorganic antibacterial agent: 0.1-0.5 parts; Main antioxidant: 0.1-0.3 parts; Antioxidant supplement: 0.1-0.2 parts; Heat stabilizer: 0.05-0.1 parts; Auxiliary agents: 0.05-0.3 parts; Transparent nucleating agent: 0.2-0.6 parts.

2. The medical-grade propylene-butyl copolymer polypropylene composition as described in claim 1, characterized in that, The inorganic antibacterial agent is selected from at least one or more of nano-silver supported antibacterial agents, nano-zinc oxide, and nano-copper oxide. The inorganic antibacterial agent is preferably a nano-silver supported antibacterial agent, and the carrier of the nano-silver supported antibacterial agent is montmorillonite or zeolite.

3. The medical-grade propylene-butyl copolymer polypropylene composition as described in claim 1, characterized in that, The main antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, or octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

4. The medical-grade propylene-butyl copolymer polypropylene composition as described in claim 1, characterized in that, The auxiliary antioxidant is tris(2,4-di-tert-butylphenyl) phosphite or bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite.

5. The medical-grade propylene-butyl copolymer polypropylene composition as described in claim 1, characterized in that, The heat stabilizer is didodecyl thiodipropionate or hindered amine light stabilizer. The hindered amine light stabilizer is light stabilizer UV-770.

6. The medical-grade propylene-butyl copolymer polypropylene composition as described in claim 1, characterized in that, The auxiliary agent is calcium stearate or zinc stearate.

7. The medical-grade propylene-butyl copolymer polypropylene composition as described in claim 1, characterized in that, The transparent nucleating agent is nucleating agent NX8000 or a sorbitol-based transparent nucleating agent; The sorbitol-based transparent nucleating agent is selected from one or more of unmodified sorbitol nucleating agents and modified sorbitol nucleating agents; preferably, it is a modified sorbitol nucleating agent. The unmodified sorbitol nucleating agent is dibenzylidene sorbitol (DBS), and the modified sorbitol nucleating agent is poly(1,3:2,4-di(3,4-dimethyl)benzyl sorbitol (NHS-9999).

8. A method for preparing a medical-grade propylene-butyl copolymer polypropylene composition as described in any one of claims 1-7, characterized in that, Includes the following steps: (1) Place each raw material component in a high-speed mixer according to the formula and stir for 5-10 minutes at a speed of 1000-1500 r / min; (2) Add the mixture from step (1) to a twin-screw extruder, melt-blend, extrude and granulate. The extrusion temperature is 180-210℃ and the screw speed is 100-200r / min to achieve melt dispersion. (3) After the mixture is cooled in a water tank, it is granulated by a pelletizer to obtain a medical grade propylene-butadiene copolymer polypropylene composition.

9. The preparation method according to claim 8, characterized in that, In step (2), the extrusion temperature zone 1 is 180-190℃, the extrusion temperature zone 2 is 190-200℃, and the extrusion temperature zone 3 is 200-210℃.

10. The use of the medical-grade propylene-butyl copolymer polypropylene composition according to any one of claims 1-7 in medical devices.

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