Low-heat-release thin-wall flame-retardant polycarbonate (PC) material and preparation method thereof

Abstract

The invention provides a low-heat-release thin-wall flame-retardant polycarbonate (PC) material and a preparation method thereof. The low-heat-release thin-wall flame-retardant polycarbonate (PC) material comprises the following raw materials in percentage by weight: 85-95 parts of polycarbonate; 2.5 to 7.5 parts of polysiloxane; and 2.5 to 10 parts of kaolin. The invention develops a halogen-free and fluorine-free synergistic flame-retardant system, under the condition of ensuring thin-wall flame retardance of the polycarbonate material, heat release of the material can be remarkably reduced, meanwhile, the impact resistance of the material is considered, and the halogen-free and fluorine-free synergistic flame-retardant system has a wide application scene.

Description

Technical Field

[0001] This invention relates to the field of materials technology, and in particular to a low-heat-release thin-walled flame-retardant polycarbonate (PC) material and its preparation method. Background Technology

[0002] Rail transit equipment is rapidly developing towards higher speeds, lighter weight, safer operation, and greener standards. This places extremely stringent requirements on the lightweighting, structural strength, fire safety, and environmental friendliness of car bodies and interior components. Polycarbonate (PC) and its alloys are widely used in railway vehicle body panels, interior structural components, equipment shells, and decorative panels due to their excellent mechanical properties, good dimensional stability, and ease of molding and processing.

[0003] With the continuous upgrading of domestic and international rail transit fire protection standards, the materials for car body components must not only possess excellent mechanical and molding properties, but also meet key indicators such as low heat release rate, low smoke density, low smoke toxicity, no dripping, and high self-extinguishing properties. This is to minimize the thermal hazards and smoke risks in fire accidents and ensure the safe evacuation time for passengers and drivers. Traditional flame-retardant PC materials are prone to problems such as high heat release and insufficient flame-retardant stability under thin-walled conditions, making it difficult to meet the integrated requirements of modern railway vehicles for high fire resistance, thin-walled lightweight, and long service life.

[0004] Therefore, this invention focuses on the application scenarios of railway vehicle body components, developing low-heat-release, thin-walled, high-efficiency flame-retardant polycarbonate materials. The emphasis is on improving its flame-retardant, smoke-suppressing, heat-suppressing properties and mechanical reliability under thin-walled conditions, enabling it to meet the stringent fire safety regulations in the rail transit field. This research can provide technical reference for material selection and engineering applications of lightweight and high-safety components in rail transit vehicles.

[0005] Traditional flame-retardant polycarbonates mostly rely on the addition of fluorinated flame retardants or anti-dripping agents to achieve a relatively ideal thin-wall flame-retardant effect. However, fluorinated substances such as PFAS (perfluoroalkyl and polyfluoroalkyl substances) are persistent, bioaccumulative, and toxic. Accumulation in the human body may lead to immunosuppression, endocrine disorders, and carcinogenic risks. Recently, many environmental regulations have imposed mandatory requirements on fluorinated substances. The EU's REACH regulation and the POPs Convention plan to comprehensively restrict approximately 12,000 fluorinated compounds (such as the flame retardant potassium perfluorobutyl sulfonate (KSS) and the anti-dripping agent polytetrafluoroethylene (PTFE)) from 2025. China's "List of Key Controlled New Pollutants" (2023) also includes PFOS and PFOA within its restricted scope. Therefore, many products currently face industrial compliance pressures, and traditional fluorinated systems are difficult to simultaneously meet both thin-wall flame-retardant and environmental protection requirements.

[0006] However, fluorinated flame retardants play a crucial role in thin-walled flame retardancy. Thin-walled flame retardancy is closely related to the material's anti-dripping properties during combustion, which depend on the increase in melt viscosity and the charring barrier effect during combustion. For example, KSS catalyzes PC crosslinking at high temperatures, forming a dense char layer that blocks the transfer of heat and combustible gases during combustion, causing the flame to extinguish rapidly. PTFE anti-dripping agents can increase melt strength and suppress dripping by forming a fibrous network structure during combustion. However, current systems have several problems: 1. Low charring efficiency: Phosphorus / nitrogen-based flame retardants require high addition amounts, which degrades mechanical properties; while silicon-based flame retardants are environmentally friendly, the char layer strength is insufficient. 2. Poor dispersibility and compatibility: Inorganic fillers (such as titanium dioxide and flake alumina) are easily catalytically decomposed, requiring silane coating modification, but the dispersion process is complex. Improper handling of charring agents (such as polyarylamide and polyphenylene sulfide) can lead to stress concentration in the aggregate, resulting in decreased impact performance. Third, it is difficult to increase the melt viscosity. For example, PTFE substitutes such as organosilicon microspheres lack a fiber network structure and have weak physical entanglement, so they are still prone to dripping during thin-walled combustion.

[0007] Current flame-retardant technologies and patents for thin-walled polycarbonate mainly achieve their effect by compounding silicon-based, phosphorus-based, or sulfonate-based flame retardants. The following are some current technical solutions for fluorine-free thin-walled flame-retardant polycarbonate:

[0008] Application publication number CN117467265A discloses a halogen-free thin-walled flame-retardant polycarbonate composite material, its preparation method, and its application. The thin-walled polycarbonate material comprises the following components by weight: 68-89 parts polycarbonate base, 5-25 parts charring agent masterbatch, 0.1-2 parts organosilicon flame retardant, 0.1-5 parts phosphazene flame retardant, 0.5-3 parts toughening agent, 0.1-1 part antioxidant, 0.5-2 parts silicone oil, and 0.5-5 parts additives. The halogen-free thin-walled flame-retardant polycarbonate material provided by this technical solution has excellent mechanical properties, good thin-walled flame-retardant performance, does not contain perfluoroalkyl or polyfluoroalkyl substances, and is safe and environmentally friendly, meeting the flame test requirements of GB / T 4943.1-2022.

[0009] Application publication number CN119144139A discloses a high-impact, thin-walled, flame-retardant polycarbonate composite material and its preparation method. The thin-walled polycarbonate material comprises the following components by mass: 84.5-95 parts polycarbonate, 0.5-1.5 parts sulfonate flame retardant, 2-5 parts phosphorus-based flame retardant, 1-5 parts amino-modified polyacrylonitrile, 0.1-1 parts mesophase carbon microspheres, 1-5 parts toughening agent, and 0.1-0.5 parts antioxidant. The thin-walled polycarbonate material provided by this technical solution exhibits excellent stability and flame retardancy, and is suitable for a wide range of applications.

[0010] Application publication number CN103709708A discloses a high-flowability glass fiber reinforced halogen-free flame-retardant polycarbonate composite material and its preparation method. The polycarbonate material comprises the following components by weight: 50-90 parts polycarbonate, 10-30 parts glass fiber, 0-10 parts flow modifier, 0.1-1 parts halogen-free flame retardant, 0-2 parts flame retardant synergist, 0.1-1 parts lubricant, and 0.1-1 parts antioxidant. When diphenyl sulfonate is selected as the halogen-free flame retardant, the glass fiber reinforced fluorine-free thin-walled flame-retardant polycarbonate material provided by this technical solution has low cost, excellent mechanical properties, and strong processing flowability.

[0011] Existing thin-walled polycarbonate flame retardant technologies, while achieving thin-walled flame retardancy through the compounding of various types of flame retardants, mostly involve the addition of fluorinated flame retardants or anti-dripping agents. Furthermore, in fluorine-free solutions, the notched impact resistance of polycarbonate often deteriorates due to the large amount of added flame retardants. Additionally, most of these technologies lack cone calorimetry test data.

[0012] Therefore, developing polycarbonate flame-retardant materials with certain notched impact resistance and good performance in various fire safety tests remains a challenge for industry and academia. Summary of the Invention

[0013] In view of this, the present invention provides a thin-walled flame-retardant polycarbonate (PC) material with low heat release. The material provided by the present invention can pass the 1.6mm vertical burning test, while the heat release is significantly reduced. This achieves a significant improvement in flame retardant performance while maintaining good notched impact performance of the polycarbonate composite material.

[0014] This invention provides a low-heat-release, thin-walled, flame-retardant polycarbonate (PC) material, comprising the following raw materials by weight percentage:

[0015] 85-95 parts polycarbonate;

[0016] 2.5 to 7.5 parts of polysiloxane;

[0017] 2.5 to 10 parts of kaolin.

[0018] In one embodiment of the present invention, the polysiloxane has a structure of formula (I).

[0019]

[0020] Where x is 4 and y is 1

[0021] In one embodiment of the present invention, the method for preparing the polysiloxane of formula (I) specifically includes:

[0022] A) Octamethylcyclotetrasiloxane, 3-aminopropylmethyldiethoxysilane, tetramethylammonium hydroxide pentahydrate, dimethyl sulfoxide and deionized water are mixed and stirred to react, and then the reaction is continued after rotary evaporation to obtain the intermediate product aminopropylpolysiloxane.

[0023] B) Dissolve aminopropyl polysiloxane in a solvent and react it with 1,8-naphthalenedicarboxylic anhydride to obtain the product.

[0024] In one embodiment of the present invention, the mass ratio of octamethylcyclotetrasiloxane, 3-aminopropylmethyldiethoxysilane, and tetramethylammonium hydroxide is 1:1:0.001.

[0025] In one embodiment of the present invention, step A) involves stirring at 90-110°C for 3.5-4.5 hours; and rotary evaporation is performed at 55-65°C for 25-30 minutes.

[0026] In one embodiment of the present invention, step A) continuing the reaction specifically includes: raising the temperature to 120°C, stirring the reaction for 24 hours, raising the temperature to 180°C, and reacting under reduced pressure for 1 hour;

[0027] The reaction continues and is then dried, which is done at 120°C for 10-12 hours.

[0028] In one embodiment of the present invention, the solvent in step B) is tetrahydrofuran; the mass ratio of the aminopropyl polysiloxane to 1,8-naphthalenedicarboxylic anhydride is 1:1.

[0029] The reaction was carried out by stirring at 80°C for 10-12 hours.

[0030] In one embodiment of the invention, the polycarbonate comprises a homopolymer of polycarbonate having repeating carbonate units, preferably an aromatic polycarbonate. Suitable polycarbonates in this invention can be prepared by methods such as interfacial polymerization and melt polymerization. In a particular embodiment, the polycarbonate is a linear homopolymer derived from bisphenol A, i.e., a polycarbonate containing a bisphenol A structure. The weight-average molecular weight of the polycarbonate, as determined by gel permeation chromatography, is from about 20,000 to about 40,000.

[0031] This invention provides a method for preparing the thin-walled flame-retardant polycarbonate (PC) material described above, comprising the following steps:

[0032] The product is obtained by melt blending polycarbonate, polysiloxane and kaolin.

[0033] In one embodiment of the present invention, the melt blending specifically includes: melt blending at 240°C and 60 rpm for 1.5 min, and then melt blending at 100 rpm for 5 min.

[0034] Compared with existing technologies, this invention provides a low-heat-release, thin-walled flame-retardant polycarbonate (PC) material, comprising the following raw materials by weight percentage: 85-95 parts polycarbonate; 2.5-7.5 parts polysiloxane; and 2.5-10 parts kaolin. This invention improves the notched impact strength of the material while providing excellent flame-retardant properties through polysiloxane, and further enhances the flame-retardant properties through kaolin. The synergistic effect of these components results in excellent performance in both vertical burning tests and cone calorimetry tests. Attached Figure Description

[0035] Figure 1 The polysiloxane in this invention 1 H NMR spectrum. Detailed Implementation

[0036] This invention provides a low-heat-release, thin-walled, flame-retardant polycarbonate (PC) material and its preparation method. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the same result. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and fall within the scope of this invention. The methods and applications of this invention have been described through preferred embodiments. Those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0037] It should be understood that the expression “one or more of…” individually includes each of the objects described after the expression, as well as various different combinations of two or more of the described objects, unless otherwise understood from the context and usage. The expression “and / or” combined with three or more described objects should be understood to have the same meaning, unless otherwise understood from the context.

[0038] The terms “including,” “having,” or “containing,” including the use of their grammatical synonyms, should generally be understood as open-ended and non-restrictive, for example, not excluding other unstated elements or steps, unless otherwise specifically stated or understood from the context.

[0039] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural.

[0040] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items.

[0041] The purpose of this invention is to prepare a low-heat-release, thin-walled flame-retardant polycarbonate composite material. This polycarbonate composite material exhibits high flame retardancy and good impact resistance, achieving a 1.6mm UL94 V-0 flame retardancy rating, reducing total heat release by more than 35%, reducing total smoke release by more than 55%, and achieving a minimum MARHE of 98.

[0042] This invention provides a low-heat-release, thin-walled, flame-retardant polycarbonate (PC) material, comprising the following raw materials by weight percentage:

[0043] 85-95 parts polycarbonate;

[0044] 2.5 to 7.5 parts of polysiloxane;

[0045] 2.5 to 10 parts of kaolin.

[0046] The low heat release thin-walled flame-retardant polycarbonate material provided by this invention comprises 85-95 parts by weight of polycarbonate; specifically, it can be 85 parts by weight, 86 parts by weight, 87 parts by weight, 88 parts by weight, 89 parts by weight, 90 parts by weight, 91 parts by weight, 92 parts by weight, 93 parts by weight, 94 parts by weight, or 95 parts by weight, or any value within the range of the above two.

[0047] In one embodiment of the invention, the polycarbonate comprises a homopolymer of aromatic polycarbonate having repeating carbonate units. Suitable polycarbonates in this invention can be prepared by methods such as interfacial polymerization and melt polymerization. In a particular embodiment, the polycarbonate is a linear homopolymer derived from bisphenol A, i.e., a polycarbonate containing a bisphenol A structure. The weight-average molecular weight of the polycarbonate, as determined by gel permeation chromatography, is from about 20,000 to about 40,000.

[0048] The polycarbonate mentioned in this invention can be polycarbonate M7027BF.

[0049] The low heat release thin-walled flame-retardant polycarbonate material provided by this invention comprises 2.5 to 10 parts by weight of kaolin; specifically, it can be 2.5 parts by weight, 3.0 parts by weight, 3.5 parts by weight, 4.0 parts by weight, 4.5 parts by weight, 5.0 parts by weight, 5.5 parts by weight, 6.0 parts by weight, 6.5 parts by weight, 7.0 parts by weight, 7.5 parts by weight, 8.0 parts by weight, 8.5 parts by weight, 9.0 parts by weight, 9.5 parts by weight, or 10.0 parts by weight, or any value within the range of the above two.

[0050] The low heat release thin-walled flame-retardant polycarbonate material provided by this invention comprises 2.5 to 7.5 parts by weight of polysiloxane; specifically, it can be 2.5 parts by weight, 3.0 parts by weight, 3.5 parts by weight, 4.0 parts by weight, 4.5 parts by weight, 5.0 parts by weight, 5.5 parts by weight, 6.0 parts by weight, 6.5 parts by weight, 7.0 parts by weight, or 7.5 parts by weight, or any value within the range of the above two.

[0051] In one embodiment of the present invention, the polysiloxane has a structure of formula (I).

[0052]

[0053] Where x is 4 and y is 1

[0054] In one embodiment of the present invention, the method for preparing the polysiloxane of formula (I) specifically includes:

[0055] A) Octamethylcyclotetrasiloxane, 3-aminopropylmethyldiethoxysilane, tetramethylammonium hydroxide pentahydrate, dimethyl sulfoxide and deionized water are mixed and stirred to react, and then the reaction is continued after rotary evaporation to obtain the intermediate product aminopropylpolysiloxane.

[0056] B) Dissolve aminopropyl polysiloxane in a solvent and react it with 1,8-naphthalenedicarboxylic anhydride to obtain the product.

[0057] The polysiloxane flame retardant of the present invention is synthesized from octamethylcyclotetrasiloxane, 3-aminopropylmethyldiethoxysilane and 1,8-naphthalenedicarboxylic anhydride.

[0058] The method for preparing polysiloxane provided by this invention first involves mixing octamethylcyclotetrasiloxane, 3-aminopropylmethyldiethoxysilane, tetramethylammonium hydroxide pentahydrate, dimethyl sulfoxide, and deionized water in a reactor and stirring the mixture. The stirring reaction is carried out at a temperature of 90-110°C, specifically at 90°C, 91°C, 92°C, 93°C, 94°C, 95°C, 96°C, 97°C, 98°C, 99°C, 100°C, 101°C, 102°C, 103°C, 104°C, 105°C, 106°C, 107°C, 108°C, 109°C, or 110°C. The reaction time is 3.5-4.5 hours; more preferably, the stirring reaction is carried out at 100°C for 4 hours.

[0059] The reaction continues after rotary evaporation to obtain the intermediate product aminopropyl polysiloxane; the rotary evaporation is carried out at 55-65°C for 25-30 min. Preferably, the rotary evaporation is carried out at 60°C for 30 min.

[0060] In one embodiment of the present invention, step A) continuing the reaction specifically includes: raising the temperature to 120°C, stirring the reaction for 24 hours, raising the temperature to 180°C, and reacting under reduced pressure for 1 hour.

[0061] The reaction continues and then drying is performed, which involves placing the product in a vacuum oven and drying it at 120°C for 10-12 hours; more preferably, drying it at 120°C for 12 hours.

[0062] The mass ratio of octamethylcyclotetrasiloxane, 3-aminopropylmethyldiethoxysilane, and tetramethylammonium hydroxide is 1:1:0.001.

[0063] The aminopropyl polysiloxane is dissolved in a solvent and reacted with 1,8-naphthalenedicarboxylic anhydride to obtain the product. The solvent used in this invention is tetrahydrofuran.

[0064] The intermediate product, aminopropyl polysiloxane, was obtained as a transparent, colorless, viscous liquid. Then, the aminopropyl polysiloxane was dissolved in tetrahydrofuran, and 1,8-naphthalenedicarboxylic anhydride was added with stirring. After stirring and cooling, the product was obtained by precipitation with n-hexane.

[0065] According to the present invention, the reaction is carried out by stirring at 80°C for 10-12 hours; preferably, the reaction is carried out by stirring at 80°C for 12 hours.

[0066] In one embodiment of the present invention, the mass ratio of the aminopropyl polysiloxane to 1,8-naphthalenedicarboxylic anhydride is 1:1.

[0067] This invention provides a method for preparing the thin-walled flame-retardant polycarbonate (PC) material described above, comprising the following steps:

[0068] The product is obtained by melt blending polycarbonate, polysiloxane and kaolin.

[0069] In one embodiment of the present invention, the melt blending specifically includes: melt blending at 240°C and 60 rpm for 1.5 min, and then melt blending at 100 rpm for 5 min.

[0070] Flame-retardant polycarbonate composite material was obtained. The obtained sample was then melted / pressed at 240°C for 15 min using a flat vulcanizing apparatus, followed by pressing at room temperature for 3 min to obtain the molded sample.

[0071] The present invention aims to enable polycarbonate to possess both notched impact resistance and thin-wall flame retardant properties without adding fluorinated flame retardants or anti-dripping agents.

[0072] This invention aims to simultaneously improve the impact resistance and flame retardant properties of polycarbonate composites, and provides a method for preparing a low-heat-release, thin-walled flame-retardant polycarbonate. On one hand, polysiloxanes provide excellent flame retardant properties while improving the notched impact strength of the material; on the other hand, the addition of kaolin further enhances the flame retardant properties, resulting in excellent performance in both vertical burning tests and cone calorimetry tests.

[0073] This invention achieves excellent flame retardant properties in composite materials by synergistically compounding polysiloxane, polycarbonate, and kaolin, while maintaining no significant decrease in mechanical properties.

[0074] This invention provides a thin-walled flame-retardant polycarbonate composite material with low heat release, achieving the following effects:

[0075] 1. Passed the 1.6mm vertical burning test;

[0076] 2. Impact performance showed no significant decrease;

[0077] 3. The heat release from the flue gas was significantly reduced in the cone calorimetry test, and MARHE was significantly reduced;

[0078] This study achieved a significant improvement in flame retardant properties while maintaining good notched impact resistance in polycarbonate composite materials.

[0079] It should be understood that the order of the steps or the order in which certain actions are performed is not important as long as the invention remains operational. Furthermore, two or more steps or actions can be performed simultaneously.

[0080] The use of any and all instances or exemplary language such as “e.g.” or “including” in this document is for the purpose of better illustrating the invention and does not constitute a limitation on the scope of the invention. No language in this specification should be construed as indicating that any unclaimed element is essential to the practice of the invention.

[0081] Furthermore, the numerical ranges and parameters used to define the present invention are approximate values, and the relevant values ​​in the specific embodiments have been presented as precisely as possible. However, any value inevitably contains standard deviations due to individual test methods. Therefore, unless explicitly stated otherwise, it should be understood that all ranges, quantities, values, and percentages used in this disclosure are modified with the word "approximately". Here, "approximately" generally means that the actual value is within plus or minus 10%, 5%, 1%, or 0.5% of a specific value or range.

[0082] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0083] The embodiments and comparative examples of this invention describe some examples, in which the embodiments illustrate certain implementations of the invention. However, this does not mean that the effects of the invention can only be achieved in these examples.

[0084] To further illustrate the present invention, the following describes in detail, with reference to embodiments, a low-heat-release thin-walled flame-retardant polycarbonate (PC) material and its preparation method provided by the present invention.

[0085] The experimental materials used in the following embodiments of the present invention can all be purchased from the market or prepared according to conventional preparation methods well known to those skilled in the art. Some of the materials and their sources are shown in Table 1 below:

[0086] Table 1

[0087]

[0088] The preparation of the polysiloxane in this embodiment of the invention is specifically as follows:

[0089] 29.7 g of octamethylcyclotetrasiloxane and 19.1 g of 3-aminopropylmethyldiethoxysilane were added to a reactor and stirred until homogeneous. Then, 3.6 g of water, 0.025 g of tetramethylammonium hydroxide pentahydrate, and 0.5 g of dimethyl sulfoxide were added, and the mixture was stirred at 100°C for 4 h. Small molecules were then removed by vacuum distillation. The temperature was raised to 120°C, and the reaction was continued with stirring for 24 h. After the reaction was complete, the temperature was raised to 160°C, and the reaction was carried out under reduced pressure for 1 h to deactivate the catalyst and remove small molecule products. After cooling, the mixture was dried in a vacuum oven at 120°C for 12 h to obtain the intermediate product, aminopropyl polysiloxane, with a yield of 86%. 41.3 g of the prepared aminopropyl polysiloxane was then dissolved in 300 mL of tetrahydrofuran, and 19.8 g of 1,8-naphthalenedicarboxylic anhydride was added with stirring. The mixture was stirred and refluxed at 80°C for 12 h, and the solvent was removed by rotary evaporation under reduced pressure to obtain a polysiloxane containing an imide structure with a yield of 95%. The resulting polysiloxane has the structure of formula (I), where x:y is 4:1.

[0090] Example 1

[0091] 90 parts of polycarbonate, 2.5 parts of polysiloxane, and 7.5 parts of kaolin were added to a torque rheometer and melt-blended at 240°C and 60 rpm for 1.5 min, followed by melt-blending at 100 rpm for 5 min to obtain the flame-retardant polycarbonate composite material. The obtained sample was then melt- / pressed at 240°C for 15 min using a flat vulcanizing apparatus, followed by pressing at room temperature for 3 min to obtain the molded sample.

[0092] Example 2

[0093] 90 parts of polycarbonate, 5 parts of polysiloxane, and 5 parts of kaolin were added to a torque rheometer and melt-blended at 240°C and 60 rpm for 1.5 min, followed by melt-blending at 100 rpm for 5 min to obtain the flame-retardant polycarbonate composite material. The obtained sample was then melt- / pressed at 240°C for 15 min using a flat vulcanizing apparatus, followed by pressing at room temperature for 3 min to obtain the molded sample.

[0094] Example 3

[0095] 90 parts of polycarbonate, 7.5 parts of polysiloxane, and 2.5 parts of kaolin were added to a torque rheometer and melt-blended at 240°C and 60 rpm for 1.5 min, followed by melt-blending at 100 rpm for 5 min to obtain the flame-retardant polycarbonate composite material. The obtained sample was then melt- / pressed at 240°C for 15 min using a flat vulcanizing apparatus, followed by pressing at room temperature for 3 min to obtain the molded sample.

[0096] Example 4

[0097] 85 parts of polycarbonate, 5 parts of polysiloxane, and 10 parts of kaolin were added to a torque rheometer and melt-blended at 240°C and 60 rpm for 1.5 min, followed by melt-blending at 100 rpm for 5 min to obtain the flame-retardant polycarbonate composite material. The obtained sample was then melt- / pressed at 240°C for 15 min using a flat vulcanizing apparatus, followed by pressing at room temperature for 3 min to obtain the shaped sample.

[0098] Comparative Example 1

[0099] 95 parts of polycarbonate and 5 parts of polysiloxane 1 were added to a torque rheometer and melt-blended at 240°C and 60 rpm for 1.5 min, then melt-blended at 100 rpm for 5 min to obtain the flame-retardant polycarbonate composite material. The obtained sample was then melt- / pressed at 240°C for 15 min using a flat vulcanizing apparatus, followed by pressing at room temperature for 3 min to obtain the molded sample.

[0100] Comparative Example 2

[0101] 95 parts of polycarbonate and 5 parts of polysiloxane 2 were added to a torque rheometer and melt-blended at 240°C and 60 rpm for 1.5 min, then melt-blended at 100 rpm for 5 min to obtain the flame-retardant polycarbonate composite material. The obtained sample was then melt- / pressed at 240°C for 15 min using a flat vulcanizing apparatus, followed by pressing at room temperature for 3 min to obtain the shaped sample.

[0102] Comparative Example 3

[0103] 90 parts of polycarbonate and 10 parts of kaolin were added to a torque rheometer and melt-blended at 240°C and 60 rpm for 1.5 min, followed by melt-blending at 100 rpm for 5 min to obtain the flame-retardant polycarbonate composite material. The obtained sample was then melt- / pressed at 240°C for 15 min using a flat vulcanizing apparatus, followed by pressing at room temperature for 3 min to obtain the molded sample.

[0104] Performance testing

[0105] Vertical burning tests (UL94), cone calorimetry tests, and impact performance tests were conducted on the polycarbonate composite materials obtained in Examples 1-7 and Comparative Examples 1-3. The test methods are as follows:

[0106] UL-94: ASTM D3801, for vertical burning tests;

[0107] Cone calorimetry test: conducted according to ISO 5660 standard, sample thickness 3 mm, surface heat flow rate 50 kW / m2.

[0108] Impact performance testing: based on standard GB / T 1843-2008

[0109] The test results are shown in Table 2 (where PHRR represents peak heat release rate, THR represents total heat release, TSP represents total smoke release, PSPR represents peak smoke release rate, and MARHE represents maximum average heat release rate):

[0110] Table 2

[0111]

[0112] Specifically,

[0113]

[0114] The polysiloxane of the present invention has the structure of formula (I), while the polysiloxane in Comparative Example 2 has the structure of formula (II). The specific synthesis method of polysiloxane (II) is as follows:

[0115] 29.7 g of octamethylcyclotetrasiloxane, 0.015 g of tetramethylammonium hydroxide pentahydrate, and 0.3 g of dimethyl sulfoxide were added to a reactor and stirred until homogeneous. The mixture was stirred at 100°C for 4 h. The temperature was then raised to 120°C, and the reaction was continued for 24 h. After the reaction was completed, the temperature was raised to 160°C, and the reaction was carried out under reduced pressure for 1 h to deactivate the catalyst and remove small molecule products. After cooling, the mixture was dried in a vacuum oven at 120°C for 12 h to obtain polydimethylsiloxane with a yield of 89%. The obtained polysiloxane has the structure of formula (II).

[0116] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A low-heat-release, thin-walled, flame-retardant polycarbonate (PC) material, characterized in that, The raw materials include the following weight percentages: 85-95 parts polycarbonate; 2.5 to 7.5 parts of polysiloxane; 2.5 to 10 parts of kaolin.

2. The low heat release thin-walled flame-retardant polycarbonate (PC) material according to claim 1, characterized in that, The polysiloxane has the structure of formula (I). Where x is 4 and y is 1.

3. The low heat release thin-walled flame-retardant polycarbonate (PC) material according to claim 1, characterized in that, The specific method for preparing the polysiloxane of formula (I) includes: A) Octamethylcyclotetrasiloxane, 3-aminopropylmethyldiethoxysilane, tetramethylammonium hydroxide pentahydrate, dimethyl sulfoxide and deionized water are mixed and stirred to react, and then the reaction is continued after rotary evaporation to obtain the intermediate product aminopropylpolysiloxane. B) Dissolve aminopropyl polysiloxane in a solvent and react it with 1,8-naphthalenedicarboxylic anhydride to obtain the product.

4. The low heat release thin-walled flame-retardant polycarbonate (PC) material according to claim 3, characterized in that, The mass ratio of octamethylcyclotetrasiloxane, 3-aminopropylmethyldiethoxysilane, and tetramethylammonium hydroxide is 1:1:0.

001.

5. The low heat release thin-walled flame-retardant polycarbonate (PC) material according to claim 3, characterized in that, The stirring reaction in step A) is carried out at 90~110°C for 3.5~4.5h; the rotary evaporation is carried out at 55~65°C for 25~30min.

6. The low heat release thin-walled flame-retardant polycarbonate (PC) material according to claim 1, characterized in that, The specific steps of step A) continuing the reaction include: raising the temperature to 120°C, stirring the reaction for 24 hours, raising the temperature to 180°C, and reacting under reduced pressure for 1 hour; The reaction continues and is then dried, which is done at 120°C for 10-12 hours.

7. The low heat release thin-walled flame-retardant polycarbonate (PC) material according to claim 1, characterized in that, The solvent in step B) is tetrahydrofuran; the mass ratio of aminopropyl polysiloxane to 1,8-naphthalenedicarboxylic anhydride is 1:

1. The reaction was carried out by stirring at 80°C for 10-12 hours.

8. The low heat release thin-walled flame-retardant polycarbonate (PC) material according to claim 1, characterized in that, The polycarbonate comprises homopolymers having repeating carbonate units.

9. A method for preparing a low-heat-release, thin-walled flame-retardant polycarbonate (PC) material according to any one of claims 1 to 8, characterized in that, Includes the following steps: The product is obtained by melt blending polycarbonate, polysiloxane and kaolin.

10. The preparation method according to claim 9, characterized in that, The melt blending specifically includes: melt blending at 240°C and 60 rpm for 1.5 min, followed by melt blending at 100 rpm for 5 min.

Images