Fluorine-free ionic liquid flame-retardant polycarbonate composite material and preparation method thereof

Abstract

The application discloses a kind of fluorine-free ion liquid flame-retardant polycarbonate composite material and preparation method thereof.The material includes polycarbonate resin 77-99.98%, phenylsiloxane flame retardant 0.01-8%, synergistic flame retardant 0.01-3%, processing aid 0-2% by mass percentage;Wherein, the phenylsiloxane flame retardant is tetramethyl hexaphenyl tetrasiloxane;The synergistic flame retardant includes 1-ethyl-3-methyl imidazole diethyl phosphate and 1-butyl-3-methyl imidazole methane sulfonate.The flame-retardant polycarbonate composite material of the application completely avoids the use of fluorine-containing synergist, meets the environmental protection regulation requirements of perfluoroalkyl compounds (PFAS), while achieving UL-94 V0 level flame retardant performance, with high light transmittance and excellent mechanical properties, suitable for automobile lightweight trim, 5G communication equipment shell and high-end optical instrument lens precision manufacturing field.

Description

Technical Field

[0001] This invention relates to the field of polymer materials, and in particular to a fluorine-free ionic liquid flame-retardant polycarbonate composite material and its preparation method. Background Technology

[0002] Polycarbonate (PC), a thermoplastic engineering plastic with excellent comprehensive properties, contains a carbonate structure in its molecular chain, giving it high impact strength, good transparency, mechanical stability over a wide temperature range, and excellent electrical insulation properties. These characteristics make it widely used in the automotive, electronics, and building materials industries, especially in automotive lighting systems, interior parts, and intelligent central control components. However, PC's flame retardancy only meets the UL94 V-2 standard, which is insufficient to meet the stringent flame retardancy requirements of modern transportation vehicles, such as the EU EN45545 and the US FAR standards. These standards not only require materials to meet the UL94 V-0 flame retardancy rating but also emphasize low heat release and low smoke toxicity to ensure passenger safety.

[0003] To improve the overall performance of polycarbonate (PC) materials, flame retardant modification technology has become a key breakthrough. While traditional halogenated flame retardants can effectively suppress flames, they do not meet the environmental requirements for perfluoroalkyl substances (PFAS) and pose environmental and health risks. In contrast, fluorine-free ionic liquid flame retardants have become a research hotspot due to their environmental friendliness and high efficiency. However, developing fluorine-free ionic liquid flame-retardant PC composites faces multiple technical challenges: balancing flame retardancy and mechanical properties to prevent a decrease in material strength; resolving the compatibility issue between the ionic liquid and the PC matrix to avoid phase separation affecting uniformity; and meeting stringent fire safety performance requirements by controlling heat release rate, smoke toxicity, and combustion drips during a fire. This poses a significant challenge to formulation design and preparation processes. Current research focuses primarily on blending modification, but maintaining PC transparency and processing flowability while improving flame retardancy levels remains a challenge. Furthermore, the introduction of fluorine-free ionic liquids may increase costs, necessitating optimization of preparation methods to reduce costs. Therefore, developing high-efficiency, environmentally friendly fluorine-free ionic liquid flame-retardant PC composites that meet PFAS standards is of significant practical importance, as it can expand the application of PC in high-end fields and promote the green development of flame-retardant materials.

[0004] Chinese patent CN202510583971.1 relates to a flame-retardant polycarbonate material, its preparation method, and its application. This material uses a silicon-co-polymerized polycarbonate compounded with reactive organosilicon flame retardants and organophosphorus flame retardants, producing a significant synergistic flame-retardant effect. It effectively controls dripping during combustion, achieving an anti-dripping effect similar to PTFE, and meeting the environmental requirements of PFAS-free production. Chinese patent CN202511160305.3 discloses a halogen-free flame-retardant polycarbonate film material, its preparation method, and its application. In this material, hollow ceramic flame-retardant microspheres sealed with organosilicon can reduce the migration of internal ammonium polyphosphate flame retardants. Simultaneously, the organosilicon layer acts as a transition layer, alleviating the thermal stress caused by the difference in thermal expansion coefficients between the polycarbonate resin and the microspheres. During the preparation of the flame-retardant board, it is coated onto the nanoplatelet with silicone. The organosilicon layer enhances the compatibility between the microspheres and silicone, and promotes silicon migration during the flame-retardant process to form a dense carbon layer, which synergistically works with the ammonium polyphosphate inside the microspheres to achieve phosphorus-silicon synergistic flame retardancy. Chinese patent CN202510349902.4 discloses a flame-retardant polycarbonate and its preparation method. By introducing a compounded siloxane copolymerized polycarbonate and a flame retardant into polycarbonate resin, it not only ensures the initial flame-retardant performance under thin-wall conditions but also possesses high transparency and resistance to damp heat. Even in long-term humid and hot environments, it can maintain excellent flame-retardant and transparent effects. Although current technologies can partially achieve a balance between flame retardancy and transparency, they suffer from problems such as high flame retardant addition amounts, significant limitations on resins, and severe technological homogenization. Therefore, developing novel flame retardants or synergistic systems has become a key research direction. Based on meeting the fluorine-free requirement, exploring synergistic flame-retardant combinations or molecular structure design to significantly improve flame-retardant performance while maintaining material transparency is of significant research importance. Summary of the Invention

[0005] To fill a gap in existing technologies, this invention provides a fluorine-free ionic liquid flame-retardant polycarbonate composite material and its preparation method. This method is based on molecular assembly design principles and uses a novel phenylsiloxane as the flame retardant. While maintaining the long-term stability and consistent appearance of the material, it maximizes the preservation of matrix transparency. The aromatic char layer catalyzed by the synergistic flame retardant serves as a framework supporting the silicon-oxygen ceramic layer. The two are fused to form a high-strength, high-stability carbon-silicon composite protective layer, significantly improving heat insulation, oxygen suppression, smoke blocking, and anti-drip performance. In terms of environmental compliance, it is a fluorine-free material, and its composition fully complies with PFAS regulations. In terms of optical performance, the impact on the light transmittance of polycarbonate is significantly reduced, making it suitable for precision manufacturing fields such as lightweight automotive interior parts, 5G communication equipment housings, and high-end optical instrument lenses.

[0006] This invention is achieved through the following technical solution:

[0007] In a first aspect, the present invention provides a fluorine-free ionic liquid flame-retardant polycarbonate composite material, comprising the following raw materials in weight percentages:

[0008] Polycarbonate resin 77-99.98%;

[0009] Phenylsiloxane flame retardant 0.01-8%;

[0010] Synergistic flame retardant 0.01-3%;

[0011] Processing aids 0-2%.

[0012] Furthermore, the polycarbonate resin is composed of resin A and resin B in a mass ratio of (1-4):1, wherein resin A has a weight-average molecular weight of 25,000-50,000, a melt flow rate (300℃, 1.2kg) of 5-15g / 10min, and a light transmittance (GB / T2410-2008) ≥85%; and resin B has a weight-average molecular weight of 30,000-50,000, a melt flow rate (300℃, 1.2kg) of 2-10g / 10min, and a branching ratio ≥20%.

[0013] Furthermore, the phenylsiloxane flame retardant is tetramethylhexaphenyltetrasiloxane, with a density of 1.11±0.1 g / cm³ and a boiling point of 640.6±38.0℃.

[0014] Furthermore, the synergistic flame retardant comprises 1-ethyl-3-methylimidazolium diethyl phosphate and 1-butyl-3-methylimidazolium methane sulfonate, in a mass ratio of (2-10.5):1.

[0015] Furthermore, the processing aids include one or more of antioxidants, lubricants, toughening agents, and heat-resistant agents.

[0016] Secondly, the present invention provides a method for preparing the fluorine-free ionic liquid flame-retardant polycarbonate composite material, comprising the following steps:

[0017] (1) Weigh the polycarbonate resin, flame retardant, synergistic flame retardant and processing aid according to the formula ratio, and mix them evenly with a high-speed mixer for later use.

[0018] (2) The mixture is added to the main feed port of a twin-screw extruder and melt-extruded in the range of 220-240℃. After granulation and drying, a fluorine-free flame-retardant transparent polycarbonate material is obtained.

[0019] Thirdly, the present invention provides the application of the above-mentioned fluorine-free ionic liquid flame-retardant transparent polycarbonate material in precision manufacturing fields such as lightweight automotive trim parts, 5G communication equipment housings, and high-end optical instrument lenses.

[0020] This invention provides a fluorine-free ionic liquid flame-retardant polycarbonate composite material and its preparation method. Based on the principle of molecular assembly design, a novel phenylsiloxane flame retardant is selected. In its molecular structure, the benzene ring and the polycarbonate matrix maintain the long-term stability and appearance consistency of the material through a similarity-mixture mechanism, while maximizing the transparency of the matrix. During combustion, the phenylsiloxane forms a dense silicon-carbon ceramic layer on the material surface to achieve efficient flame retardancy. The aromatic char layer generated by the synergistic flame retardant acts as a skeleton to support the silicon-oxygen ceramic layer. The two are fused to form a high-strength carbon-silicon composite protective layer, which significantly improves the heat insulation, oxygen suppression, smoke blocking and anti-drip performance. Three major breakthroughs are achieved through precise molecular-level design: the flame retardant performance passes the UL94 V-0 level test (1.6mm) without dripping, the composition fully complies with PFAS regulations, and the light transmittance is >88%. It is suitable for precision manufacturing fields such as lightweight automotive trim parts, 5G communication equipment housings and high-end optical instrument lenses.

[0021] The beneficial effects of this invention are as follows:

[0022] 1) Innovative flame retardant design: A novel phenylsiloxane is selected as the flame retardant. During combustion, the phenylsiloxane forms a dense silicon-carbon ceramic layer on the material surface to achieve efficient flame retardancy. The benzene ring in its molecular structure is uniformly dispersed with the polycarbonate matrix based on the principle of similar solubility, which effectively avoids migration and seepage, thereby maintaining the long-term stability, appearance consistency and high transparency of the material.

[0023] 2) Optimization of synergistic flame retardant mechanism: The synergistic flame retardant catalyzes the formation of an aromatic coke layer, which serves as a skeleton to support the silicon-oxygen ceramic layer. The two are fused together to form a high-strength, high-stability carbon-silicon composite protective layer, which significantly improves the heat insulation, oxygen suppression, smoke blocking and anti-drip performance. This technology completely avoids fluorinated synergists and complies with the environmental regulations for perfluoroalkyl compounds (PFAS).

[0024] 3) Innovative Resin Compound Structure: By compounding high molecular weight and branched structure resins in a specific mass ratio, the melt strength of polycarbonate is improved and the dripping of molten material during combustion is suppressed; the high molecular weight component promotes the formation of a dense char layer, which, together with the synergist, enhances the char layer encapsulation effect and further optimizes the anti-dripping property.

[0025] 4) Comprehensive performance and environmental friendliness: The material is free of fluorine and fully meets PFAS requirements. It also has excellent mechanical properties, flame retardant properties and high visible light transmittance, achieving a unity of environmental protection concept and high performance characteristics.

[0026] Through the above innovations, the flame-retardant polycarbonate material of this invention has comprehensive advantages such as excellent mechanical properties, outstanding flame retardant properties, and high visible light transmittance, and meets the needs of sustainable development. Detailed Implementation

[0027] The core innovation of this invention lies in the following: Based on molecular structure design, phenylsiloxane achieves structural compatibility with the polycarbonate matrix through a benzene ring, ensuring uniform dispersion and no migration of the flame retardant, maintaining the long-term service stability and appearance consistency of the material; during combustion, a dense Si-O-Si / Si-C cross-linked ceramic layer is formed on the material surface, achieving highly efficient flame retardancy while maximizing the preservation of the matrix transparency. The aromatic char layer catalyzed by the synergistic flame retardant serves as a framework supporting the silicon oxide ceramic layer. The two are fused to form a high-strength, high-stability carbon-silicon composite protective layer, significantly improving heat insulation, oxygen suppression, smoke blocking, and anti-drip performance.

[0028] To make the technical problem to be solved, the technical solution, and the beneficial effects of the present invention clearer, the present invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are only for explaining the present invention and are not intended to limit the present invention.

[0029] The embodiments and comparative examples of the present invention use the following materials, but are not limited to the following materials:

[0030] Polycarbonate PC, Resin A, Trade Name Makrolon® 2805, manufactured by Covestro;

[0031] Polycarbonate PC, resin B, trade name WB2032, produced by Wanhua;

[0032] Flame retardant: Tetramethylhexaphenyltetrasiloxane, produced by Alfa Chemistry;

[0033] Synergistic flame retardant: 1-ethyl-3-methylimidazolium diethyl phosphate (CAS: 848641-69-0), produced by Zhejiang Lande Energy Technology Development Co., Ltd.;

[0034] Synergistic flame retardant: 1-Butyl-3-methylimidazolium methane sulfonate, produced by Shanghai Haohong Biomedical Technology Co., Ltd.;

[0035] Halogen-free phosphate flame retardant: Bisphenol A-bis(diphenyl phosphate) BDP, trade name WSFR-BDP, produced by Wansheng, Zhejiang;

[0036] Anti-dripping agent: Polytetrafluoroethylene (PTFE), trade name DB105, produced by Suzhou Pulefei;

[0037] Organosiloxane flame retardant, trade name ADDITIVE 40-001, manufactured by Dow Corning;

[0038] Lubricant, PETS, trade name: GLYCOLUBE® P (ETS), manufactured by Lonza, USA;

[0039] Antioxidant 1010, trade name: JYANOX 1010, manufactured by Jiyi;

[0040] Antioxidant 168, trade name: JYANOX-168, produced by Jiyi.

[0041] Examples 1-4 and Comparative Examples 1-7 each provide a flame-retardant polycarbonate composite material, the raw material composition of which is shown in Table 1 below.

[0042] Preparation method of flame-retardant polycarbonate composite material:

[0043] (1) Weigh the polycarbonate resin, flame retardant, synergistic flame retardant and processing aid according to the formula ratio (the specific types of additives are based on the component formula in Table 1), and mix them evenly with a high-speed mixer for later use.

[0044] (2) The mixture is added to the main feed port of a twin-screw extruder and melt-extruded in the range of 220-240℃. After granulation and drying, a fluorine-free flame-retardant transparent polycarbonate material is obtained.

[0045] Preparation of test strips for flame-retardant polycarbonate materials:

[0046] The above materials were dried in a forced-air drying oven at 120℃ for 4 hours, and then injection molded into standard specimens at an injection molding temperature of 220-270℃. The prepared mechanical property specimens were then conditioned in a standard laboratory environment (23℃, 50%RH) for 24 hours before testing.

[0047] Test methods for each performance indicator:

[0048] Tensile properties: According to ISO 527 method, specimen size: 170*10*4mm, test speed 5mm / min.

[0049] Bending performance: According to ISO 178 method, the sample size is 80*10*4mm, and the test speed is 2mm / min.

[0050] Notched impact performance: according to ISO 179 method, spline size: 80*10*4mm.

[0051] Flame retardant performance: According to UL94 method, the sample size is 127*12.7*1.6mm.

[0052] Light transmittance: According to ASTM D1003-2011 method, sample size: 60*60*2mm

[0053] The test methods for each performance indicator are shown in Table 1 below:

[0054] Table 1: Composition and properties of flame-retardant polycarbonate materials in Examples 1-4 and Comparative Examples 1-7

[0055]

[0056] Based on the test results of the examples and comparative examples in Table 1, the present invention can achieve UL 94 V-0 flame retardant performance without adding fluorinated flame retardants. Specifically, a comparison of Examples 1-4 with Comparative Example 4 shows that, with the same amount of synergistic flame retardant added, the flame retardant efficiency of the present invention is significantly better than that of bisphenol A bisphosphate. A comparison with Comparative Examples 1-2 shows that the composite system of 1-ethyl-3-methylimidazolium diethyl phosphate and 1-butyl-3-methylimidazolium methane sulfonate has better flame retardant performance than a single component. It catalyzes the formation of an aromatic char layer as a framework supporting the silicon-oxygen ceramic layer. The fusion of these two components forms a high-strength, high-stability carbon-silicon composite protective layer, significantly improving heat insulation, oxygen suppression, smoke and drip resistance, and optimizing flame retardant performance. Examples 1-4 and Comparative Examples 6-7 show that a specific mass ratio of high molecular weight and branched resin can improve the melt strength of polycarbonate and suppress combustion dripping; the high molecular weight component promotes the formation of a dense char layer, synergistically enhancing the char layer's encapsulation effect with the char-forming agent to optimize anti-dripping properties. Meanwhile, comparisons between Examples 1-4 and Comparative Example 3 confirm that the flame-retardant efficiency of the synergist of this invention is superior to that of silicon-based flame retardants. A comparison between Example 1 and Comparative Example 5 shows that, under the same flame retardant addition amount, the material's light transmittance and flame-retardant efficiency are superior to fluorinated flame-retardant PC. The flame retardant of this invention does not contain fluorine, does not release toxic gases or fumes during combustion, complies with PFAS environmental regulations, and is a fluorine-free environmentally friendly material suitable for precision manufacturing fields such as lightweight automotive trim parts, 5G communication equipment housings, and high-end optical instrument lenses.

Claims

1. A fluorine-free ionic liquid flame-retardant polycarbonate composite material and its preparation method, characterized in that: It consists of the following raw materials by weight percentage: Polycarbonate resin 77-99.98%; Phenylsiloxane flame retardant 0.01-8%; Synergistic flame retardant 0.01-3%; Processing aids 0-2%; Wherein: the phenylsiloxane flame retardant is tetramethylhexaphenyltetrasiloxane; the synergistic flame retardant includes 1-ethyl-3-methylimidazolium diethyl phosphate and 1-butyl-3-methylimidazolium methane sulfonate.

2. The fluorine-free ionic liquid flame-retardant polycarbonate composite material according to claim 1, characterized in that: The polycarbonate resin is composed of resin A and resin B; wherein resin A has a weight-average molecular weight of 25,000-50,000, a melt flow rate of 5-15 g / 10 min, and a light transmittance of ≥85%, and resin B has a weight-average molecular weight of 30,000-50,000, a melt flow rate of 2-10 g / 10 min, and a branching ratio of ≥20%.

3. The fluorine-free ionic liquid flame-retardant polycarbonate composite material according to claim 2, characterized in that: The mass ratio of resin A to resin B is (1-4):

1.

4. The fluorine-free ionic liquid flame-retardant polycarbonate composite material according to claim 1, characterized in that: The phenylsiloxane flame retardant tetramethylhexane has a density of 1.11±0.1 g / cm³ and a boiling point of 640.6±38.0℃.

5. The fluorine-free ionic liquid flame-retardant polycarbonate composite material according to claim 1, characterized in that: The mass ratio of the synergistic flame retardant 1-ethyl-3-methylimidazolium diethyl phosphate to 1-butyl-3-methylimidazolium methane sulfonate is (2-10.5):

1.

6. The fluorine-free ionic liquid flame-retardant polycarbonate composite material according to claim 1, characterized in that: The processing aids include one or more of antioxidants, lubricants, toughening agents, and heat-resistant agents.

7. The method for preparing the fluorine-free ionic liquid flame-retardant polycarbonate composite material according to any one of claims 1-6, characterized in that: Includes the following steps: (1) Weigh the polycarbonate resin, flame retardant, synergistic flame retardant and processing aid according to the formula ratio, and mix them evenly with a high-speed mixer for later use. (2) The mixture is added to the main feed port of a twin-screw extruder and melt-extruded in the range of 220-240℃. After granulation and drying, a fluorine-free flame-retardant transparent polycarbonate material is obtained.

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