Radiation-resistant polycarbonate material and preparation method thereof

Abstract

According to the radiation-resistant polycarbonate material and the preparation method thereof, the radiation-resistant polycarbonate material is prepared from the following raw materials in parts by mass: 94.0 to 99.8 parts of polycarbonate resin, 0.1 to 1 part of an antioxidant and 0.1 to 5 parts of a high-radiation-resistant auxiliary agent. According to the polycarbonate material prepared by the invention, the material cost is effectively reduced, and the polycarbonate material shows excellent radiation resistance, instant color stability and innovative application of a high-radiation-resistance auxiliary agent.

Description

Technical Field

[0001] The invention belongs to the field of polymer composite material processing, and particularly relates to a radiation-resistant polycarbonate material and a preparation method thereof. Background Art

[0002] With the increasing global health awareness and the rapid progress of medical technology, the medical device industry has ushered in an unprecedented period of development opportunities. In the context of the widespread application of sterile medical devices, disinfection and sterilization, as a key link to ensure the safety of medical devices, is of self-evident importance. At present, there are many sterilization methods such as ethylene oxide sterilization, dry heat sterilization, steam sterilization and irradiation sterilization. Irradiation sterilization technology has gradually occupied a dominant position in the medical device sterilization market with its significant advantages such as high efficiency, thoroughness, no residue and no pollution. However, while irradiation sterilization technology improves the safety of medical devices, it also puts forward more stringent requirements on the material design of medical products. Medical plastics, especially polymer materials widely used in in vitro diagnostic equipment, high-end implants and low-value medical consumables due to their cost-effectiveness, chemical inertness and excellent biocompatibility, face challenges such as molecular chain breakage after irradiation, yellowing due to cross-linking reaction, and decreased mechanical properties. Therefore, the development of polymer materials with excellent radiation resistance is of great significance to improving the safety and durability of medical devices and promoting the continuous progress of medical technology.

[0003] Polycarbonate, as a popular thermoplastic in the field of medical devices, is famous for its high strength and excellent optical transparency. However, under high-energy radiation, polycarbonate is prone to main chain breakage, generating phenoxy free radicals, which in turn causes irreversible yellowing, seriously affecting the appearance and transparency of medical products. To address this problem, existing technologies have attempted to improve the radiation resistance of polycarbonate by optimizing antioxidant combinations and adding specific radiation-resistant stabilizers. However, these methods still have the following shortcomings: (1) Limited yellowing resistance: The yellow index after irradiation is high, and the color recovery relaxation time is long. It takes several weeks to significantly reduce the yellowing, which significantly prolongs the production and delivery cycle of medical devices. For example, the color of the radiation-resistant polycarbonate in CN201980026490.3 can only be restored to △YI=4.11 after 50kGy irradiation after at least 21 days of relaxation, and the color of the radiation-resistant polycarbonate in CN201210159928.5 can only be restored to 5.6 after 7 days of relaxation after 25kGy irradiation. (2) Formula complexity and potential risks: It is necessary to compound a variety of radiation-resistant additives to achieve the best effect, which not only increases the complexity of the formula, but also may introduce biocompatibility and potential safety risks. (3) The role of sulfur element has not been fully explored: Although studies have revealed the positive effects of thioether and thioester compounds on the radiation resistance of polycarbonate, the existing technical solutions have not fully explored the key mechanism of sulfur in the radiation-resistant system. It only involves sulfur connected to two benzene rings with a single bond, and the induction effect enhances the ability of polycarbonate materials to resist radiation oxidation. (4) Application limitations: It is necessary to rely on initial color matching treatment to make up for the lack of radiation resistance, and the radiation dose is limited (25kGy), which makes it difficult to meet high-end application scenarios with high color requirements or higher radiation doses, such as nuclear power, aerospace and other fields.

[0004] In summary, although the existing technology has made certain progress in improving the radiation resistance of polycarbonate, there are still many problems that need to be solved. It is urgent to develop a more efficient, safe and widely applicable radiation-resistant polycarbonate material. Summary of the invention

[0005] In view of the common problems of severe yellowing, performance degradation and complex formulation of existing polycarbonate materials when subjected to high-dose radiation, the present invention proposes a polycarbonate material with excellent radiation resistance and a preparation method thereof. The core of the present invention is the innovative introduction of a highly radiation-resistant additive with a specific structure, a vinyl aromatic compound, which, through its unique molecular design, exhibits excellent free radical capture and stabilization capabilities during the radiation process, thereby giving the polycarbonate material excellent radiation resistance.

[0006] Specifically, the radiation-resistant polycarbonate material of the present invention can still maintain the original color stability after being subjected to an irradiation dose of up to 50kGy, and can meet the stringent application requirements without the need for additional color matching or a long color recovery period. This breakthrough achievement is due to the efficient synergistic effect of the benzene ring structure and the vinyl group in the vinyl aromatic compound. The benzene ring can effectively absorb and disperse the radiation energy, while the vinyl group releases active hydrogen atoms through a ring-opening reaction under irradiation excitation, thereby effectively quenching harmful species such as phenoxy free radicals triggered by radiation, thereby blocking the free radical chain reaction, reducing the breakage and crosslinking of the molecular chain, and maintaining the overall performance stability of the material. It is particularly noteworthy that the present invention further introduces sulfur atoms into the molecular structure of the vinyl aromatic compound, and through the interaction between the lone pair of electrons of the sulfur atom and the π electron cloud of the benzene ring and the vinyl group, the electron cloud density of the molecule is significantly enhanced, and the neutralization ability of the electron-donating group to the unstable free radicals generated by irradiation is improved. This molecular design not only enhances the free radical capture efficiency, but also accelerates the free radical consumption process, so that the material can still maintain excellent color and mechanical properties at higher irradiation doses.

[0007] In terms of preparation technology, the present invention provides a simple and efficient method, which is prepared by mixing polycarbonate resin, antioxidant and high radiation resistance additive in proportion, and then melting and extruding through a twin-screw extruder and pelletizing. The method is simple to operate, easy to industrialize, and the obtained product has stable and reliable performance.

[0008] In summary, the radiation-resistant polycarbonate material and preparation method thereof provided by the present invention not only solve the key problems in the prior art, but also show broad application prospects and market competitiveness in high value-added fields such as nuclear power, electronic appliances, aerospace, etc. due to its excellent radiation resistance, simple preparation process and low material cost.

[0009] A radiation-resistant polycarbonate material and a preparation method thereof, characterized in that, in parts by mass, the raw material composition comprises: Polycarbonate resin: 94.0-99.8 parts Antioxidant: 0.1-1 part High radiation resistance additive: 0.1-5 parts The high radiation resistance auxiliary agent is a vinyl aromatic compound.

[0010] The polycarbonate resin is selected from at least one of aliphatic, aromatic, and aliphatic-aromatic; The polycarbonate resin is in the form of pellets, and has a melt index in the range of 5 to 30 g / 10 min at 300° C. and 1.2 kg.

[0011] The vinyl aromatic compounds are divided into sulfur-containing and non-sulfur-containing types, wherein the sulfur atom in the sulfur-containing vinyl aromatic compounds is connected to the benzene ring and the vinyl group in the form of single bonds.

[0012] The vinyl aromatic compound contains a structural unit shown in Formula 1, [Formula 1]

[0013] Among them, R1 is a methyl group or a benzene ring, R2 is a S atom or no group, preferably a S atom, and R1 and R2 may be in the ortho position, meta position or para position.

[0014] Preferably, the vinyl aromatic compound is at least one selected from 2-vinyltoluene, divinylbenzene, 4-vinylbiphenyl, 4,4-divinylbiphenyl, phenyl vinyl sulfide, 1,2-bis(phenylthio)ethylene, and bis(4-(vinylthio)phenyl)sulfane. Most preferably, phenyl vinyl sulfide, 1,2-bis(phenylthio)ethylene, and bis(4-(vinylthio)phenyl)sulfane are selected.

[0015] The antioxidant is a composite combination of a hydrogen donor and a hydroperoxide decomposer; The hydrogen donor is selected from at least one of 1010, 1076, 2246, 425, and 3125; The hydroperoxide decomposer is selected from at least one of 168, 9228, 626, DSTP and DLTP.

[0016] The present invention also provides a method for preparing a polycarbonate material with excellent radiation resistance, comprising adding a polycarbonate resin, an antioxidant and a high radiation resistance auxiliary agent into a high-speed mixer according to a proportion and mixing them evenly, then adding the mixture into a feeding hopper of a twin-screw extruder, setting the temperature of each zone of the extruder and the speed of the main screw, and obtaining radiation-resistant polycarbonate particles through melt extrusion and pelletizing with a pelletizer; The twin-screw extrusion temperature is 220-300° C., and the screw speed is 100-400 r / min. Preferably, the extruder temperature is 240-270° C., and the screw speed is 350-400 r / min.

[0017] Compared with the prior art, the main advantages of the present invention include: (1) Excellent radiation resistance: The polycarbonate material prepared by the present invention exhibits excellent radiation resistance and can withstand a radiation dose of up to 50 kGy without obvious color change. Therefore, it can meet the visual requirements of various application scenarios without the need for additional complex color matching processing.

[0018] (2) Innovative application of highly radiation-resistant additives: By innovatively introducing vinyl aromatic compounds as highly radiation-resistant additives in the formula, the additives can fully resist radiation-induced oxidation reactions, effectively inhibit the initiation and growth of key free radical chain reactions, and promptly eliminate the generated free radicals. More importantly, by cleverly introducing sulfur atoms between the benzene ring and the vinyl group, the neutralization ability of the charge-donating group on the unstable free radicals generated by radiation in the polycarbonate system is significantly enhanced, greatly reducing the risk of polymer molecular chain breakage, while accelerating the activation process of hydrogen atoms in unsaturated double bonds, thereby effectively curbing the spread of free radical chain reactions and further improving the radiation resistance of polycarbonate materials.

[0019] (3) Instant color stability: The polycarbonate material of the present invention can quickly reach and maintain the color requirements that meet relevant industry standards without having to wait for a long time for the relaxation and decolorization process after irradiation, which greatly improves the practicality and production efficiency of the material.

[0020] (4) Cost-optimized formula design: The polycarbonate material formula design of the present invention is simple and efficient, without the need for complex or expensive additives, which effectively reduces the material cost. This allows the material to have not only excellent performance but also significant economic advantages, which is conducive to its promotion and application in a wider range of fields. Implementation

[0021] The present invention will be further described below in conjunction with specific examples. It should be understood that these examples are only intended to illustrate the present invention and are not intended to limit the scope of the present invention. The operating methods for the following examples without specifying specific conditions are usually performed under conventional conditions or under conditions recommended by the manufacturer.

[0022] The raw material composition of each embodiment is calculated by mass fraction, and the detailed proportion is shown in Table 1. The main raw material is aromatic polycarbonate, and its melt flow index is 10g / min. For comparison, the known radiation-resistant additives A (N,N'-ethylenebis(stearic acid amide)) and B (bis(4-hydroxyphenyl) sulfide) are used in the comparative example, both of which are radiation-resistant additives disclosed in existing patents and applied to polycarbonate systems. In the embodiments of the present invention, radiation-resistant additives C (2-vinyltoluene), D (4,4-divinylbiphenyl), E (1,2-bis(phenylthio)ethylene) and F (bis(4-(vinylthio)phenyl)sulfane) are creatively used.

[0023] The preparation method is as follows: Each raw material component was accurately weighed according to the ratio in Table 1 and added to a high-speed mixer. After being mixed evenly, it was transferred to a twin-screw extruder. The heating zone temperature of the extruder was set to 240°C to 260°C, and the screw speed was adjusted to 350r / min. Melt extrusion was performed under the above-set process conditions, and then the extruded molten material was quickly cooled and pelletized by a water cooling device, and finally polycarbonate particles with excellent radiation resistance were obtained.

[0024] Table 1 Components / Specifications Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Example 3 Example 4 Polycarbonate resin / Aromatic polycarbonate 100 98.5 98.0 98.0 98.0 98.0 98.0 98.3 Antioxidant / 168 / 1 1 1 1 1 1 1 Antioxidant / 1010 / 0.5 0.5 0.5 0.5 0.5 0.5 0.5 Radiation resistant additive / A / / 0.5 / / / / / Radiation resistant additive / B / / / 0.5 / / / / Radiation resistant additive / C / / / / 0.5 / / / Radiation resistance additive / D / / / / / 0.5 / / Radiation resistant additive / E / / / / / / 0.5 / Radiation resistance additive / F / / / / / / / 0.2 The polycarbonate particles prepared above were processed into uncolored samples with a thickness of 2 mm by injection molding. The polycarbonate samples were irradiated with electron beams generated by electron accelerators, and the irradiation doses were set to 25 kGy and 50 kGy, respectively. The yellowness index (YI) of the samples before and after irradiation was measured according to ASTM D1925 standard. The difference between the yellowness index before and after irradiation of 25 kGy and 50 kGy was obtained by calculation, which was expressed as △YI 25-0 and △YI 50-0 , in order to quantify the effect of irradiation on the color stability of the material. The irradiated samples were placed at room temperature and protected from light for relaxation and decolorization experiments. The yellowness index was measured again according to the ASTM D1925 standard at 1 week, 2 weeks and 3 weeks after irradiation, and compared with the yellowness index before irradiation, and the corresponding yellowness index difference △YI was calculated. 25-1 ,△YI 25-2 ,△YI 25-3 and △YI 50-1 ,△YI 50-2 ,△YI 50-3 , this step aims to evaluate the material's ability to decolorize over time after irradiation.

[0025] Table 2 Components / Specifications Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Example 1 Example 2 Example 3 Example 4 Initial Yellowness Index (YI) 1.8 1.7 1.5 1.6 1.8 1.6 1.6 1.7 YI after 25kGy irradiation 23.8 20.2 14.1 15.2 12.8 9.7 4.9 3.0 <![CDATA[△YI 25-0 ]]> 22.0 18.5 12.6 13.6 11.0 8.1 3.3 1.3 YI after 25kGy irradiation for 1 week 22.6 19.7 10.8 12.4 6.1 5.6 1.7 1.9 <![CDATA[△YI 25-1 ]]> 20.8 18.0 9.3 10.8 4.3 4.0 0.1 0.2 YI after 2 weeks of 25 kGy irradiation 22.1 19.2 7.2 7.2 3.2 2.2 1.7 1.8 <![CDATA[△YI 25-2 ]]> 20.3 17.5 5.7 5.6 1.4 0.6 0.1 0.1 YI after 25kGy irradiation for 3 weeks 21.5 18.4 4.9 5.3 2.8 2.0 1.7 1.7 <![CDATA[△YI 25-3 ]]> 19.7 16.7 3.4 3.7 1.0 0.4 0.1 0 YI after 50kGy irradiation 45.2 42.5 30.8 35.2 17.6 16.5 11.0 7.0 <![CDATA[△YI 50-0 ]]> 43.4 40.8 29.3 33.6 15.8 14.9 9.4 5.3 YI after 1 week of 50 kGy irradiation 43.1 41.6 22.6 25.8 6.0 7.2 5.6 2.2 <![CDATA[△YI 50-1 ]]> 41.3 39.9 21.1 24.2 4.2 5.6 4.0 0.5 YI after 2 weeks of 50 kGy irradiation 42.4 40.9 15.4 19.7 5.2 6.0 3.9 1.9 <![CDATA[△YI 50-2 ]]> 40.6 39.2 13.9 18.1 3.4 4.4 2.3 0.2 YI after 50 kGy irradiation for 3 weeks 41.9 40.1 7.5 10.3 3.5 3.7 2.0 1.9 <![CDATA[△YI 50-3 ]]> 40.1 38.4 6.0 8.7 1.7 2.1 0.4 0.2 According to the data shown in Table 2, Comparative Example 1 is a polycarbonate resin without adding a modifier, which shows a high radiation sensitivity, specifically, the yellow index reaches 23.8 after 25kGy irradiation, and increases to 45.2 after 50kGy irradiation, and the yellow index does not change significantly with time, indicating that the sample has limited decolorization ability during the relaxation period. Comparative Example 2 introduces commonly used antioxidants 1010 and 168. Although these antioxidants improve the radiation resistance of polycarbonate materials to a certain extent, the yellowing phenomenon after irradiation is still significant, and no significant improvement in decolorization ability is observed. Compared with the above comparative examples, Comparative Examples 3 and Comparative Examples 4 are modified using the reported radiation resistance additives N,N'-ethylenebis(stearic acid amide) and bis(4-hydroxyphenyl) sulfide, respectively. The results show that these two additives effectively reduce the yellowness index of polycarbonate after 25kGy and 50kGy irradiation to 14.1, 15.2 and 30.8, 35.2, respectively, significantly improving the radiation resistance of the material and giving the sample good color recovery ability during the relaxation period. In particular, after 3 weeks of relaxation after 50kGy irradiation, △YI 50-3 to 6.0 and 8.7 respectively. Examples 1 to 4 of the present invention creatively introduce the vinyl aromatic compounds described in this patent as modifiers. Among them, 2-vinyltoluene and 4,4-divinylbiphenyl are added to Example 1 and Example 2 respectively. Compared with traditional radiation-resistant additives, these vinyl aromatic compounds significantly enhance the radiation resistance of polycarbonate materials, making the yellow index less than 20 after 50kGy irradiation, and can reduce the yellow index to below 10 in a short time (such as 1 week relaxation). Furthermore, Examples 3 and 4 use the sulfur-containing vinyl aromatic compounds 1,2-bis(phenylthio)ethylene) and bis(4-(vinylthio)phenyl)sulfane unique to this patent. By introducing S atoms between the benzene ring and the vinyl group, not only the reaction activity of the compound is improved, but also its radiation resistance effect is greatly enhanced. Specifically, after 50kGy irradiation, the yellow index of polycarbonate is reduced to 11.0 and 7.0 respectively, and the decolorization speed and effect are better than the existing radiation-resistant additives.

[0026] The present invention provides a polycarbonate material with excellent radiation resistance and a preparation method thereof. The method adds a vinyl aromatic compound rich in benzene ring structure, electron-donating group or vinyl group and an antioxidant in a coordinated manner, and particularly introduces an S atom between the benzene ring and the vinyl group, thereby utilizing the electron-donating effect to increase the reactivity of the sulfur-containing vinyl aromatic compound, thereby effectively neutralizing the unstable free radicals generated by the polycarbonate system due to radiation, reducing the risk of polymer molecular chain breakage, accelerating the activation of hydrogen atoms in unsaturated double bonds, and efficiently inhibiting the free radical chain reaction. After being irradiated up to 50 kGy, the prepared polycarbonate material can meet the yellow index standard of related products without relaxation time.

[0027] In addition, it should be understood that after reading the above description of the present invention, those skilled in the art may make various changes and modifications to the present invention, and these equivalent forms also fall within the scope defined by the claims attached to this application.

Claims

1. A radiation-resistant polycarbonate material, characterized in that: In parts by mass, the raw material composition includes: Polycarbonate resin: 94.0-99.8 parts Antioxidant: 0.1-1 part High radiation resistance additive: 0.1-5 parts The high radiation resistance auxiliary agent is a vinyl aromatic compound, and the vinyl aromatic compound contains a structural unit shown in Formula 1, [Formula 1] Among them, R1 is a methyl group, a vinyl group or a benzene ring, R2 is an S atom or no group, preferably an S atom, and R1 and R2 may be in the ortho position, meta position or para position.

2. The radiation-resistant polycarbonate material according to claim 1, characterized in that: The vinyl aromatic compound is selected from one or more of phenyl vinyl sulfide, 1,2-bis(phenylthio)ethylene, and bis(4-(vinylthio)phenyl)sulfane.

3. The radiation-resistant polycarbonate material according to claim 1, characterized in that: The polycarbonate resin is selected from at least one of aliphatic, aromatic, and aliphatic-aromatic; it is in the form of pellets, and has a melt index in the range of 5 to 30 g / 10 min at 300° C. and 1.2 kg.

4. The radiation-resistant polycarbonate material according to claim 1, characterized in that: The antioxidant is a composite combination of a hydrogen donor and a hydroperoxide decomposer, wherein the hydrogen donor is selected from at least one of 1010, 1076, 2246, 425, and 3125; and the hydroperoxide decomposer is selected from at least one of 168, 9228, 626, DSTP, and DLTP.

5. The method for preparing a radiation-resistant polycarbonate material according to any one of claims 1 to 4, characterized in that: The polycarbonate resin, antioxidant and high radiation resistance auxiliary agent are added into a high mixer according to a proportion and mixed evenly, and then the mixture is added into a feeding hopper of a twin-screw extruder, and the temperature of each zone of the extruder and the main screw speed are set, and radiation-resistant polycarbonate particles are obtained by melt extrusion and pelletizing with a pelletizer; the twin-screw extrusion temperature is 220-300°C, and the screw speed is 100-400r / min. Preferably, the extruder temperature is 240-270°C, and the screw speed is 350-400r / min.

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