Antibacterial flame-retardant polycarbonate composite material as well as preparation method and application thereof

Abstract

The invention belongs to the field of plastic materials, and particularly discloses an antibacterial flame-retardant polycarbonate composite material as well as a preparation method and application thereof. The antibacterial flame-retardant polycarbonate composite material disclosed by the invention is prepared from the following components in parts by weight: 100 parts of polycarbonate, 0.45 to 3.1 parts of a flame retardant and 0.4 to 1.6 parts of nano zinc oxide, the flame retardant is prepared from polydimethylsiloxane and phenyl-containing organic silicon resin; the micro-morphology of the nano zinc oxide is at least one of a needle shape and a rod shape. The antibacterial flame-retardant polycarbonate composite material disclosed by the invention contains the needle-like nano zinc oxide, the polydimethylsiloxane and the phenyl-containing organic silicon resin, so that the antibacterial flame-retardant polycarbonate composite material has the comprehensive properties of long-acting flame retardance, antibacterial property and mildew resistance, and is more suitable for being used in a scene which often needs to be in contact with water or is in a humid environment.

Description

Technical Field

[0001] This invention belongs to the field of plastics, specifically relating to an antibacterial and flame-retardant polycarbonate composite material, its preparation method, and its application. Background Technology

[0002] Polycarbonate (PC) is an engineering plastic with excellent comprehensive performance. It boasts the highest impact resistance among thermoplastics and exhibits good dimensional stability, high heat distortion temperature, weather resistance, and electrical conductivity. It is widely used in the automotive, electronics, home appliance, wearable device, and smart pet products industries. PC resin has a limiting oxygen index of 26% and is self-extinguishing upon removal of the flame. However, in practical applications, better flame retardancy is desired for PC materials. Among existing halogen-free flame retardants for PC, traditional intumescent phosphate ester flame retardants such as triphenyl phosphate (TPP), resorcinol-bis(diphenyl phosphate) RDP, and bisphenol A-bis(diphenyl phosphate) BDP have drawbacks such as high dosage requirements and the risk of leaching, leading to environmental pollution and material performance degradation. Furthermore, as intumescent flame retardants, they crack during the foaming process in water or humid environments, reducing oxygen and heat insulation effects and causing a decline in flame retardant performance. Therefore, they are unsuitable for PC materials used in scenarios requiring frequent contact with water or humid environments. Although sulfonate flame retardants are used in PC systems in small quantities, they require sophisticated dispersion processes and are hygroscopic. For PC materials frequently exposed to water or humid environments, this can lead to flame retardant failure, and the reaction products may also pose environmental hazards. Therefore, existing flame retardants are insufficient in improving the long-term flame retardant performance of PC materials frequently exposed to water or humid environments, failing to meet practical needs.

[0003] Meanwhile, with increasing health awareness, plastic products that frequently come into contact with water or humid environments not only need to have good flame retardant properties, but also require long-lasting antibacterial and antifungal functions. Existing antibacterial agents mainly work by killing bacteria or inhibiting their reproduction. For example, inorganic antibacterial agents such as nano-silver, copper, zinc ions and their oxides have advantages such as broad-spectrum bactericidal activity, high safety, good temperature resistance, and low likelihood of developing drug resistance. However, they are costly, and the antibacterial and antifungal effects of these materials still significantly decrease or even fail when frequently exposed to water or humid environments.

[0004] Therefore, improving the long-lasting flame retardant and antibacterial / mildew-proof properties of materials that frequently come into contact with water or are used in humid environments is one of the current research priorities. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of existing materials that are frequently in contact with water or used in humid environments and have poor flame retardant, antibacterial and mildew-proof properties. This invention will provide an antibacterial and flame retardant polycarbonate composite material, its preparation method and application.

[0006] To achieve the above objectives, the following technical solutions are specifically included: On one hand, the present invention provides an antibacterial and flame-retardant polycarbonate composite material, comprising the following components in parts by weight: 100 parts of polycarbonate, 0.45-3.1 parts of flame retardant, and 0.4-1.6 parts of nano zinc oxide; wherein the flame retardant comprises polydimethylsiloxane and phenyl-containing organosilicon resin; and the nano zinc oxide has at least one of the following micromorphological forms: needle-like or rod-like.

[0007] The microstructure of nano zinc oxide is needle-like or rod-like, meaning that the zinc oxide particles are much larger in length than in the other two dimensions (diameter or width). The aspect ratio of the nano zinc oxide particles is greater than 1, preferably greater than or equal to 2, and even more preferably 3-50.

[0008] The composite material of the present invention contains needle-like or rod-like nano zinc oxide, polydimethylsiloxane, and phenyl-containing organosilicon resin, which enables the composite material to have both long-lasting flame retardant and antibacterial and antifungal effects, making it more suitable for use in scenarios that frequently come into contact with water or are in humid environments.

[0009] The inventors discovered that polydimethylsiloxane and phenyl-containing silicone resin in the system have a synergistic flame-retardant effect, significantly improving the flame-retardant performance and long-term flame-retardant properties of the composite material. This allows for a reduction in the amount of flame retardant used while maintaining good flame-retardant performance, avoiding the reduction in antibacterial properties caused by excessive flame retardant dosage. The nano-zinc oxide particles have a needle-like or rod-like morphology. Their unique elongated shape allows them to form a bridging structure with the flame retardant, increasing the density of the polysiloxane expanded char layer formed when the flame retardant is burned. This avoids the defects of conventional intumescent flame retardants, such as cracks during foaming that reduce oxygen and heat insulation effects. The polydimethylsiloxane and phenyl-containing silicone resin have good hydrophobic properties, allowing the composite material to maintain good stability in humid or water-contact environments, avoiding significant foaming and cracking that could degrade flame retardancy and antibacterial properties. Furthermore, the flame retardant and zinc oxide... When forming a bridging structure, zinc oxide is appropriately and partially coated with a hydrophobic flame retardant, which can effectively reduce the degree to which the antibacterial effect of zinc oxide is lost in humid or water-contact environments. However, if the flame retardant is unsuitable, resulting in insufficient zinc oxide coating, or if the amount of flame retardant is too large, causing the zinc oxide to be completely or excessively coated, it will affect the antibacterial performance of zinc oxide, resulting in poor antibacterial effect of the composite material. Therefore, needle-shaped or rod-shaped nano-zinc oxide can work synergistically with polydimethylsiloxane and phenyl-containing organosilicon resin flame retardants to improve the long-term flame retardant performance of the composite material when it needs to be in contact with water or in humid environments. However, if the content of nano-zinc oxide is too large, it will catalyze the decomposition of PC to produce combustible carbon monoxide, increasing the combustion time and leading to a decrease in flame retardant performance. Therefore, its dosage must be appropriate. At the same time, because nano-zinc oxide has high surface activity and a large specific surface area, it is easier to bind with bacteria and release free Zn. 2+ It can penetrate the cell membrane and enter the cell, damaging the cell membrane and reacting with groups on proteins to disrupt the bacterial structure and physiological activity, thus exerting bactericidal and antifungal effects. Furthermore, needle-shaped or rod-shaped nano-zinc oxide is more effective at piercing bacterial cells than spherical zinc oxide, maintaining long-lasting antibacterial and antifungal properties. In addition, nano-zinc oxide can catalyze the reaction of oxygen and water in the air to produce reactive oxygen species (ROS), which adsorb onto the bacterial surface, enter the cell, and disrupt its molecular structure, ultimately oxidizing it into substances such as CO2 and H2O, thereby killing bacteria and viruses and enhancing its long-lasting antibacterial and antifungal properties.

[0010] Preferably, the antibacterial and flame-retardant polycarbonate composite material comprises the following components in parts by weight: 100 parts polycarbonate, 0.5-3 parts flame retardant, and 0.5-1.5 parts nano zinc oxide.

[0011] Preferably, in the antibacterial and flame-retardant polycarbonate composite material, the mass percentage of polycarbonate (PC) is not less than 70%, more preferably not less than 80%, and even more preferably not less than 90%.

[0012] Preferably, the system of the present invention does not limit the type of polycarbonate, wherein the polycarbonate is preferably bisphenol A type polycarbonate. Commercially available conventional polycarbonate can be used, or a self-made polycarbonate can be used, such as a polycarbonate with a melt flow rate of 5-35 / 10min, wherein the melt flow rate conforms to ISO 1133-1. The 2011 standard was used for testing under the conditions of 300℃ and 1.2kg. More specifically, the melt flow rate of polycarbonate can be 5g / 10min, 6g / 10min, 8g / 10min, 10g / 10min, 12g / 10min, 14g / 10min, 16g / 10min, 18g / 10min, 20g / 10min, 22g / 10min, 24g / 10min, 26g / 10min, 26g / 10min, 28g / 10min, 30g / 10min, 32g / 10min, 34g / 10min, 35g / 10min, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0013] Polydimethylsiloxane (PDMS) is a linear organosilicon polymer. Its chemical structure consists of a main chain of alternating silicon (Si) and oxygen (O) atoms, with methyl groups (-CH3) attached to the silicon atoms; its repeating unit is -Si(CH3)2-O-. Conventional PDMS available in the art can meet the requirements of this invention. For example, more specifically, a viscosity of 10-30 mmHg obtained by testing PDMS at 25°C according to ISO 3104-2020 standard can be used. 2 / s case.

[0014] Preferably, the phenyl-containing organosilicon resin is a polymer with a three-dimensional network structure. Its molecular structure contains silicon-oxygen bonds (-Si-O-Si-) and phenyl-containing organic groups. The phenyl group has high polarity and exhibits higher compatibility in PC, allowing for more uniform dispersion within the PC matrix, thereby further improving the flame retardancy of the material. Conventional polydimethylsiloxanes in the art can meet the requirements of this invention. For example, more specifically, a phenyl-containing organosilicon resin with a softening point of 70-110℃ can be used. The softening point test method includes the following steps: Testing is performed according to GB / T 4507-2014 standard. The sample is placed in a shoulder-shaped copper ring, a standard steel ball (3.5g) is placed inside, and heating is carried out at a rate of 5℃ / min. The temperature at which the steel ball falls 25.4mm is taken as the softening point, and the initial heating rate is 23℃.

[0015] More preferably, the phenyl-containing organosilicon resin includes methylphenyl organosilicon resin.

[0016] Preferably, the polydimethylsiloxane and the phenyl-containing organosilicon resin are present in weight proportions of 0.5-2 parts and 0.1-1 parts, respectively.

[0017] Preferably, the mass ratio of the polydimethylsiloxane to the phenyl-containing organosilicon resin is (0.5-6.5):1, more preferably (0.8-4):1. More specifically, the mass ratio can be 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, 5.5:1, 6:1, 6.5:1, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0018] Polydimethylsiloxane has good flame retardancy, and phenyl-containing silicone resin has better compatibility in the system. However, polydimethylsiloxane flame retardant is more detrimental to antibacterial properties than phenyl-containing silicone resin. Through experiments, this invention has found that, under the above-mentioned mass ratio, the composite material can simultaneously possess better flame retardant and antibacterial properties.

[0019] Preferably, the average length of the nano-zinc oxide is 15-40 nm. More specifically, it can be 15 nm, 17 nm, 19 nm, 21 nm, 23 nm, 25 nm, 27 nm, 29 nm, 31 nm, 33 nm, 35 nm, 37 nm, 39 nm, 40 nm, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list all the specific values ​​included in the range.

[0020] Preferably, the mass ratio of the polydimethylsiloxane to the nano zinc oxide is (0.3-3):1, more preferably (0.5-1.5):1, and more specifically, the mass ratio can be 0.3:1, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, 3:1, etc., as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this invention will not exhaustively list the specific values ​​included in the range.

[0021] Preferably, the antibacterial and flame-retardant polycarbonate composite material further includes 0-5 parts by weight of other additives.

[0022] Preferably, the other additives include the following components in parts by weight: 0.1-1.5 parts antioxidant and 0.1-1.5 parts lubricant.

[0023] More preferably, the antioxidant is a hindered phenolic antioxidant.

[0024] On the other hand, the present invention provides a method for preparing the antibacterial and flame-retardant polycarbonate composite material, comprising the following steps: mixing, melting, extruding and granulating the raw materials in sequence to obtain the antibacterial and flame-retardant polycarbonate composite material.

[0025] Preferably, in step (3), the melting temperature is 240~270℃.

[0026] Preferably, in step (3), the rotation speed during melting is 200~600 rpm.

[0027] The present invention also provides an application of the antibacterial and flame-retardant polycarbonate composite material in the preparation of automotive trim, electronics, home appliances, wearable devices and smart pet products, and more specifically, it can be applied to the preparation of smart pet feeders and water dispensers.

[0028] Compared with the prior art, the present invention has the following beneficial effects: The antibacterial and flame-retardant polycarbonate composite material of the present invention contains needle-shaped nano zinc oxide, polydimethylsiloxane and phenyl-containing organosilicon resin, which makes it meet the comprehensive requirements of long-lasting flame retardancy and antibacterial and anti-mildew properties, thus making it more suitable for use in scenarios that frequently come into contact with water or are in humid environments. Detailed Implementation

[0029] To better illustrate the purpose, technical solution, and advantages of this invention, specific embodiments will be used to further explain the invention below. Unless otherwise specified, the experimental methods used in the embodiments and / or comparative examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available. Unless otherwise specified, the raw materials used in each embodiment and comparative example of this invention are the same in each parallel experiment.

[0030] Raw material information involved in the following examples and comparative examples: PC-1: LG Chem, PC 1300 10 NP, melt flow rate (300℃, 1.2kg) 10g / 10min; PC-2: LG Chem, PC 1300 22 NP, melt flow rate (300℃, 1.2kg) 20g / 10min; PC-3: LG Chem, PC 1300 30, melt flow rate (300℃, 1.2kg) 30g / 10min; Flame retardant-1: PPDM, DC8008, viscosity 20mm 2 / s; Flame retardant-2: Methylphenyl silicone resin, KR-480, Shin-Etsu Chemical, Japan; Flame retardant-3: Methyl aliphatic silicone resin, KR-220L, Shin-Etsu Chemical, Japan; Antibacterial agent 1: Needle-shaped nano zinc oxide, CSNM, with an average length of 15nm as measured by scanning electron microscopy, manufactured by Zhongxing Nano; Antibacterial agent 2: Needle-shaped nano zinc oxide, NMGO, with an average length of 30nm as measured by scanning electron microscopy, manufactured by Xi'an Qiyue Biotechnology; Antibacterial agent 3: Rod-shaped nano zinc oxide, KND-XB30, with an average length of 40nm as measured by scanning electron microscopy, manufactured by Changzhou Kenada New Materials; Antibacterial agent 4: Spherical nano zinc oxide, DK-ZnO-15, with an average particle size D50 of 15nm as measured by scanning electron microscopy, manufactured by Beijing Deco Island Gold Technology Co., Ltd.

[0031] Examples 1-11 and Comparative Examples 1-7 A method for preparing an antibacterial and flame-retardant polycarbonate composite material includes the following steps: According to the raw material formula in Table 1-2, the components are mixed evenly, and then melt-extruded and granulated by a twin-screw extruder at a temperature of 240~270℃ to obtain antibacterial and flame-retardant polycarbonate material.

[0032] The test methods for various properties of the antibacterial and flame-retardant polycarbonate composite materials in the embodiments and comparative examples of the present invention are as follows: (1) Long-lasting flame retardancy test method: The antibacterial and flame-retardant polycarbonate materials prepared in the above examples and comparative examples were injection molded into strips with a length of 125±5 mm, a width of 13±0.5 mm, and a thickness of 1.5 mm. The strips were then soaked in tap water for 20 days to simulate the application scenario of long-term contact with water or a humid environment. After that, they were taken out and dried for flame retardant testing. Place the Bunsen burner at the center of the sample below the flame-retardant strip, igniting it 10±1 mm from the bottom of the sample. The flame height should be 20±1 mm. After ignition for 10±0.5 s, move the Bunsen burner away at least 150 mm at a speed of 300 mm / sec, and simultaneously record the afterflame time t1. When the afterflame stops, immediately ignite the same Bunsen burner, and after ignition for 10±0.5 s, move the Bunsen burner away at least 150 mm at a speed of 300 mm / sec, and simultaneously record the afterflame time t2. Calculate the afterflame time t, where t = t1 + t2. Then calculate the average afterflame time t of 10 parallel samples, and evaluate the flame retardant rating according to the U94 test.

[0033] (2) Long-lasting antibacterial test: The antibacterial and flame-retardant polycarbonate materials prepared in the above examples and comparative examples were injection molded into strips with a length of 100 mm × 100 mm and a thickness of 2 mm. The strips were then soaked in tap water for 20 days to simulate the application scenario of long-term contact with water or a humid environment. After that, they were taken out and dried, and antibacterial tests were conducted. The antibacterial test method was in accordance with GB / T 31402-2015 / ISO 22196:2007(IDT) Plastics—Test method for antibacterial properties of plastic surfaces. The test species were Escherichia coli and Staphylococcus aureus.

[0034] (3) Anti-mildew test: In accordance with GB / T 2423.16-2022 standard, the antibacterial and flame-retardant polycarbonate composite materials prepared in the above examples and comparative examples were placed in an environment with a humidity of 60RH and a temperature of 23 degrees Celsius for 30 days for testing. The test strains were Aspergillus niger, Aspergillus terreus, Trichoderma viride, Penicillium cordiformis, Chaetomium globosum, Penicillium wansii, Trichoderma breviculatum, and Ascomycota resinosa.

[0035] Rating criteria: Grade 0: No mold growth: No growth observed under a microscope (50x magnification); Level 1: Mold traces are visible under a microscope; Grade 2a: Sparse mold visible to the naked eye or scattered, localized mold visible under a microscope, with the moldy area not exceeding 5% of the test area; Grade 2b: Mold is clearly visible to the naked eye in many places, with the moldy area not exceeding 25% of the test area; Grade 3: Mold is clearly visible to the naked eye, with the moldy area exceeding 25% of the test area.

[0036] Grade 0 and Grade 1 indicate good anti-mildew performance.

[0037] The test results are shown in Table 3.

[0038] Table 1 (parts by weight) Table 2 (parts by weight) Table 3 Compared to Example 1, Comparative Example 1, being pure PC, lacks flame retardants and antibacterial agents, resulting in poor antibacterial, mildew-proof, and flame-retardant effects in the composite material. Comparative Example 2 lacks polydimethylsiloxane, and Comparative Example 3 lacks phenyl-containing organosilicon resin. The absence of one of the flame retardants in Comparative Examples 2 and 3 did not significantly improve the flame-retardant effect. Furthermore, the lack of a flame retardant led to inappropriate bridging structures between the flame retardant and zinc oxide, or inadequate coating of zinc oxide by the flame retardant. Consequently, the antibacterial effect of zinc oxide was poor in humid or water-contact environments, and to some extent, it also negatively impacted the antibacterial and mildew-proof effects. Comparative Example 4, lacking needle-shaped zinc oxide antibacterial agent, exhibited the worst antibacterial performance, and its flame-retardant effect also significantly decreased. Therefore, the synergistic effect of needle-shaped nano-zinc oxide, polydimethylsiloxane, and phenyl-containing organosilicon resin can significantly improve the long-lasting flame retardancy and antibacterial and mildew-proof properties of the composite material.

[0039] Meanwhile, based on the analysis of Comparative Example 5, which uses methyl aliphatic silicone resin to replace phenyl-containing silicone resin, it can be seen that methyl aliphatic silicone resin cannot significantly improve flame retardant performance, while phenyl-containing silicone resin has greater polarity and better compatibility. Moreover, its synergistic effect with polydimethylsiloxane significantly improves the flame retardant performance of the composite material, making it more suitable for the material system of this invention.

[0040] Compared with Example 1, in Comparative Example 6, changing the needle-shaped antibacterial agent to a spherical antibacterial agent did not significantly improve the antibacterial performance, nor did it significantly improve the flame retardant performance. This may be because it could not effectively penetrate bacterial cells and could not play a bridging role in the system structure, thus failing to significantly improve the antibacterial, antifungal, and flame retardant performance. Furthermore, excessive use of nano zinc oxide would lead to increased PC degradation, longer burning time, and significantly worse flame retardant performance.

[0041] As the melt flow rate of PC in Examples 1-3 increases, the flame retardant properties decrease slightly, while the antibacterial properties remain essentially unchanged.

[0042] In Examples 6, 5, 1, and 4, with the same total mass of polydimethylsiloxane and phenyl-containing silicone resin, the mass ratios of the two were 0.5:1, 0.875:1, 2:1, and 6.5:1, respectively. As the polydimethylsiloxane content increased, the flame retardant properties gradually increased, while the antibacterial and antifungal properties gradually decreased. Therefore, within the above-mentioned mass ratio range, the composite material exhibits long-lasting flame retardant and antibacterial / antifungal properties when used in environments with prolonged contact with water.

[0043] In Examples 7, 1, and 8, the average lengths of the nano zinc oxide were 15 nm, 30 nm, and 40 nm, respectively. As the particle length increased, the antibacterial properties decreased slightly, while the antifungal and flame-retardant properties remained basically unchanged. It can be seen that nano zinc oxide can maintain good flame-retardant, antibacterial, and antifungal properties within the nanoscale.

[0044] In Examples 9, 1, and 10, with the same total mass of polydimethylsiloxane and nano zinc oxide, the mass ratios of the two were 0.3:1, 1:1, and 3:1, respectively. In Example 11, the amount of flame retardant was increased from 1 part by weight to 2 parts by weight. As the content of polydimethylsiloxane increased and the amount of nano zinc oxide decreased, the flame retardant performance increased slightly, while the antibacterial performance decreased. Furthermore, increasing the amount of polydimethylsiloxane significantly reduced the antibacterial and antifungal performance.

[0045] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. An antimicrobial flame retardant polycarbonate composite material, characterized by, The composition comprises the following components by weight: Polycarbonate 100 parts, flame retardant 0.45-3.1 parts, nano zinc oxide 0.4-1.6 parts; the flame retardant comprises polydimethylsiloxane and phenyl-containing silicone resin; the micro-morphology of the nano zinc oxide is at least one of needle-like or rod-like.

2. The antimicrobial flame-retardant polycarbonate composite of claim 1, wherein, The mass ratio of the polydimethylsiloxane and the phenyl-containing silicone resin is (0.5-6.5):

1.

3. The antimicrobial flame-retardant polycarbonate composite of claim 1, wherein, The phenyl-containing silicone resin comprises methylphenyl silicone resin.

4. The antimicrobial, flame-retardant polycarbonate composite of claim 1, wherein the flame retardant is a halogenated flame retardant. The mass ratio of the polydimethylsiloxane and the nano zinc oxide is (0.3-3):

1.

5. The antimicrobial, flame-retardant polycarbonate composite of claim 1, wherein, The average length of the nano zinc oxide is 15-40 nm.

6. The antimicrobial, flame-retardant polycarbonate composite of claim 1, wherein, The polycarbonate has a melt flow rate of 5-35 g / 10 min at 300 DEG C, 1.2 kg under the test of ISO 1133-1 2011 standard.

7. A process for the preparation of the antibacterial flame retardant polycarbonate composite material according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: sequentially mixing, melting, extruding and granulating each raw material to obtain the antibacterial and flame-retardant polycarbonate composite material.

8. Use of the antibacterial and flame-retardant polycarbonate composite material of any one of claims 1-6 in the preparation of automobile accessories, electronics, home appliances, wearable devices and pet smart products.

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