Needle-flame-resistant transparent flame-retardant polycarbonate material and preparation method thereof

Abstract

The invention relates to a needle-flame-resistant transparent flame-retardant polycarbonate (PC) material, which is characterized in that a sulfonate flame retardant, an organic silicon synergistic flame retardant and a phosphorus-nitrogen-silicon synergistic flame retardant containing a POSS (Polyhedral Oligomeric Silsesquioxane) structure are added into the PC material, so that the flame retardance and molten mass dripping resistance of the PC material can be effectively improved, and the negative influence of a traditional PTFE (Polytetrafluoroethylene) anti-dripping agent on light transmission is avoided; meanwhile, the compatibility of phenyl and PC in the synergistic flame retardant is utilized, so that the molecular weight of the flame-retardant component is remarkably improved, the problems of insufficient timeliness and light transmittance reduction caused by small molecule migration are effectively solved, and the high physical property retention rate of the needle-flame-resistant transparent flame-retardant PC material is realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of flame-retardant materials, and in particular to a transparent flame-retardant polycarbonate material resistant to needle flame and a preparation method thereof. BACKGROUND

[0002] With the full implementation of the Chinese mandatory national standard GB 4943.1-2022 "Audio, video, information technology and communication technology equipment Part 1: Safety requirements" in August 2023, the flame-retardant performance requirements of the shell material for electronic and electrical equipment have been significantly improved. The standard clearly stipulates that when the electrical gap is insufficient, fireproof materials passing the GB / T 5169.5-2020 Appendix S.2 needle flame test (60 seconds) or UL94 V-0 level (1.0 mm thickness) need to be used.

[0003] However, the existing flame-retardant polycarbonate (PC) material faces three technical bottlenecks: traditional bromine-based flame-retardant PC can pass UL94 V-0 at 1.0 mm thickness, but due to the dominant gas-phase flame-retardant mechanism, it cannot form an effective carbon layer in the needle flame test, and generally appears to be burned through (pore diameter > 3 mm) after 60 seconds of burning; halogen-free phosphorus-based flame retardants (such as BDP) have serious migration in thin-walled samples, resulting in a decline in flame-retardant performance (UL94 decreases to V-2 level after material aging). In addition, nanoscale flame retardants (such as LDH, montmorillonite) can improve the burn-through resistance, but the refractive index mismatch causes the light transmittance to be < 80%, which cannot meet the visual requirements of display screens and optical lenses; organic silicon resins have the advantage of light transmission, but the addition amount needs to be > 10% to achieve 1.0 mm V-0, and the high addition amount leads to a decrease in melt strength (increasing the risk of melt dripping).

[0004] CN118006105A proposes a thin-walled flame-retardant PC system, in which the epoxy / aromatic amine crosslinking system can reduce the amount of flame retardant, but the crosslinking reaction introduced by it may affect the light transmittance of the matrix, and the precise addition amount control of aromatic amine is difficult, and deviation can easily cause fluctuations in flame-retardant performance (such as the self-extinguishing time of the needle flame in some embodiments is unqualified). The phosphorus-containing organic silicon resin flame retardant developed in CN101671568A has high heat resistance, but it only verifies the flame-retardant performance of 1.6 mm thick samples (oxygen index 33%), and does not solve the key needle flame resistance problem of thin-walled PC. In addition, the flame-retardant components of the two schemes may still cause stress cracking or loss of mechanical properties of the matrix (especially impact toughness) at high addition.

[0005] Therefore, for the current thin-walled PC flame-retardant material, it is still necessary to balance and improve its flame-retardant performance, burn-through resistance, mechanical properties, light transmittance, and meet the requirements of environmental protection and the like. SUMMARY

[0006] In view of the above-mentioned shortcomings of the prior art, the present invention provides a needle-flame resistant transparent flame-retardant polycarbonate (PC) material. By adding sulfonate flame retardants, organosilicon synergistic flame retardants, and phosphorus-nitrogen-silicon synergistic flame retardants with POSS structures to the PC material, the flame retardancy and anti-melt dripping performance of the PC material can be effectively improved, avoiding the negative impact of traditional PTFE anti-dripping agents on light transmittance. At the same time, by utilizing the compatibility between the phenyl group in the synergistic flame retardant and PC, the molecular weight of the flame-retardant component is significantly increased, effectively solving the problems of insufficient efficiency and decreased light transmittance caused by small molecule migration, and achieving a high property retention rate for the needle-flame resistant transparent flame-retardant PC material. The needle-flame resistant transparent flame-retardant PC material of the present invention simultaneously achieves UL94 V-0, needle flame ≥60 seconds without burn-through, and light transmittance ≥85% at a thickness of 1.0 mm. Moreover, its composition is halogen-free and PFAS-free, which complies with the EU (EU) 2021 / 1297 ban on PFAS. It can be widely used in the production of mobile phones, TV LCD displays, polycarbonate sheets, photovoltaic panels, automotive instruments, display housings, home appliances, and communication electronic components. The present invention also provides a method for preparing the aforementioned needle-flame resistant transparent flame-retardant polycarbonate material.

[0007] To achieve the above objectives, a first aspect of the present invention provides a needle flame resistant transparent flame-retardant polycarbonate material comprising the following raw materials in parts by weight: 85-95 parts of polycarbonate resin, 0.1-0.5 parts of sulfonate flame retardant, 0.1-0.5 parts of organosilicon synergistic flame retardant, and 1-10 parts of phosphorus-nitrogen-silicon synergistic flame retardant containing a POSS structure; optionally, it further comprises antioxidants, lubricants, and / or inorganic fillers.

[0008] In one embodiment, the polycarbonate resin comprises a mixture of linear polycarbonate and branched polycarbonate, wherein the content of branched polycarbonate is 10-30 parts by weight.

[0009] In one embodiment, the sulfonate flame retardant is a mixture of sodium sulfonate flame retardant and potassium sulfonate flame retardant in a weight ratio of 1:1.5 to 1:3.5.

[0010] In one embodiment, the needle-flame resistant transparent flame-retardant polycarbonate material comprises the following raw materials in parts by weight: 90-95 parts polycarbonate resin, 0.2-0.4 parts sulfonate flame retardant, 0.2-0.4 parts organosilicon synergistic flame retardant, and 2-6 parts phosphorus-nitrogen-silicon synergistic flame retardant containing a POSS structure; optionally, it further comprises antioxidants, lubricants, and / or inorganic fillers.

[0011] The linear polycarbonate can be, for example, G1010-F from Zhejiang Petrochemical, with a melt flow index (MFI) of (8-12) g / 10 min.

[0012] Branched polycarbonate can be used, for example, LG Chem's 1603-03, which has a melt index (MFI) of (2-4) g / 10 min.

[0013] The sodium sulfonate flame retardant can be sodium diphenyl sulfonate (NSS), sodium p-styrene sulfonate (NaPSS), sodium p-aminobenzene sulfonate (p-ABSA), sodium 2,4,5-trichlorobenzene sulfonate (STB), etc. Specifically, Sanguard CB211 from Sanhe Chemical can be used.

[0014] The potassium sulfonate flame retardant can be potassium diphenyl sulfonate (KSS), potassium perfluorobutyl sulfonate (PFBS), potassium p-styrene sulfonate (KPSS), etc. Specifically, Quansheng KFR-KKS-A2, KFR-KKS, or Arichem's KSS can be used.

[0015] The organosilicon synergistic flame retardant can be a siloxane-based flame retardant, including phenylsiloxanes, epoxy-modified siloxanes, polyether-modified siloxanes, etc. In one embodiment, the organosilicon synergistic flame retardant is octaphenylcyclotetrasiloxane. Specifically, F-800 from Shanghai Puxin Polymer Materials Co., Ltd. can be used.

[0016] The antioxidant can be a hindered phenolic antioxidant, a phosphate ester antioxidant, and / or a thioester antioxidant. Preferably, the antioxidant is a compound antioxidant composed of a hindered phenolic antioxidant and a phosphate ester antioxidant, for example, a compound antioxidant composed of 20% hindered phenolic antioxidant and 80% phosphate ester antioxidant. Specifically, the antioxidant Irganox B900 from BASF (Germany) can be used.

[0017] The lubricant can be a fatty acid ester lubricant or a polyether lubricant, such as pentaerythritol stearate (PETS) or glyceryl monostearate (GMS). Specifically, PETS-AHS from FACI Italy can be used.

[0018] The inorganic filler can be talc powder with a particle size (D50) of 0.6-3 μm, preferably 0.6-1.5 μm. For example, IMI Fabi HTP Ultra 5L from Italy can be used.

[0019] In one embodiment, the antioxidant in the above-mentioned polycarbonate material is 0.4-0.6 parts by weight, the lubricant is 0.2-0.4 parts by weight, and the inorganic filler is 1-3 parts by weight.

[0020] The phosphorus-nitrogen-silicon synergistic flame retardant containing the POSS structure has the structure shown in formula (1):

[0021] Equation (1)

[0022]

[0023] Where R1 is Or -CH3, and each POSS structure contains 3 to 7 R1s. R2 is Or -CH3.

[0024] It is easy to understand that in equation (1), the POSS structure is as follows: That is, a structure in which multiple R1 and aminophenyl groups are connected on a cage-like silicon-oxygen framework.

[0025] In one implementation, the two POSS structures are identical in equation (1).

[0026] In one implementation, each POSS structure contains 3, 5, or 7 R1s. Preferably, the two POSS structures are identical. More preferably, the seven R1s are... Furthermore, the two POSS structures are identical.

[0027] As an exemplary embodiment, the above-mentioned phosphorus-nitrogen-silicon synergistic flame retardant containing a POSS structure can be prepared by the following method:

[0028] (1) Dissolve T8 aminophenyl POSS in a first solvent to form a first solution; mix diphenylphosphonic acid and the first catalyst in a second solvent to form a first mixture;

[0029] (2) Under an inert atmosphere, the first mixture is added dropwise to the first solution and reacted at 60℃-100℃ for 3-8 hours. After the reaction is completed, the mixture is cooled, filtered, and washed to obtain the phosphorus-nitrogen POSS intermediate.

[0030] (3) Dissolve the phosphorus-nitrogen POSS intermediate in a third solvent to form a second solution; mix the epoxy-terminated phenylsiloxane with the second catalyst in a fourth solvent to form a second mixture;

[0031] (4) Under an inert atmosphere, the second mixture is added dropwise to the second solution and reacted at 60℃-80℃ for 2-6 hours. After the reaction is completed, the temperature is lowered, and an alkaline solution is added to quench the catalyst. The solvent is removed by separation, washing, and vacuum distillation to obtain the phosphorus-nitrogen-silicon synergistic flame retardant containing the POSS structure.

[0032] The inert gas is, for example, N2; the alkaline solution is, for example, NaHCO3 solution; and the cooling is, for example, to 20°C-40°C. However, it is not limited to these.

[0033] The first solvent, second solvent, third solvent, and fourth solvent are one or a mixture of two or more of benzene, toluene, xylene, acetonitrile, tetrahydrofuran, and dichloromethane. Preferably, all of the above solvents are anhydrous solvents.

[0034] In one embodiment, the mass concentration of T8 aminophenyl POSS in the first solution is 5%-20%, preferably 5%-8%.

[0035] In one embodiment, in step (1), the molar ratio of diphenylphosphonic acid to T8 aminophenyl POSS is (N-1):1, where N is the number of aminophenyl groups in T8 aminophenyl POSS.

[0036] In one embodiment, the first catalyst is one or a mixture of two or more of trimethylchlorosilane (TMSCl), formaldehyde, triethylamine (Et3N), dicyclohexylcarbodiimide (DCC), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC·HCl), diphenyl azidophosphate (DPPA), hydroxybenzotriazole (HOBt), and 4-dimethylaminopyridine (DMAP). The molar percentage of the first catalyst relative to diphenylphosphonic acid is 1%-8%, preferably 2%-5%.

[0037] In one embodiment, the epoxy-terminated phenylsiloxane is one or a mixture of two of epoxy-terminated diphenyltrisiloxane and epoxy-terminated phenyltrisiloxane. The molar ratio of the epoxy-terminated phenylsiloxane to T8 aminophenyl POSS is (0.8-1):2.

[0038] In one embodiment, the second catalyst is a Lewis acid catalyst, including dibutyltin dilaurate, AlCl3, BF3·Et2O, Yb(OTf)3, B(C6F5)3, or tetraisopropyl titanate. The molar percentage of the second catalyst relative to the epoxy-terminated phenylsiloxane is 1.5%-3%, preferably 2%-2.5%.

[0039] In one embodiment, the volume ratio of the third solvent to the first solvent is 1.2-1.8.

[0040] A second aspect of the present invention provides a method for preparing the above-mentioned needle-flame resistant transparent flame-retardant polycarbonate material, the method comprising the following steps:

[0041] (1) Dry the polycarbonate resin at 120℃-130℃ until the water content is less than 0.025%, and set aside for later use;

[0042] (2) According to the weight ratio, the polycarbonate resin, sulfonate flame retardant, organosilicon synergistic flame retardant, phosphorus-nitrogen-silicon synergistic flame retardant with POSS structure, and optional antioxidant, lubricant and inorganic filler are mixed evenly.

[0043] (3) The mixed raw materials are added to a twin-screw extruder for extrusion granulation to obtain the needle flame resistant transparent flame retardant polycarbonate material; wherein the processing temperature of the twin-screw extruder is 240℃-280℃ and the screw speed is 250-300 RPM.

[0044] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0045] 1. This invention provides a needle-flame resistant transparent flame-retardant polycarbonate (PC) material. By adding sulfonate flame retardants, organosilicon synergistic flame retardants, and phosphorus-nitrogen-silicon synergistic flame retardants with POSS structures to the PC material, the flame retardancy and anti-melt dripping performance of the PC material can be effectively improved, avoiding the negative impact of traditional PTFE anti-dripping agents on light transmittance. Simultaneously, by utilizing the compatibility of phenyl groups in the synergistic flame retardants with PC, the molecular weight of the flame-retardant components is significantly increased, effectively solving the problems of insufficient efficiency and decreased light transmittance caused by small molecule migration, achieving a high property retention rate for the needle-flame resistant transparent flame-retardant PC material. The needle-flame resistant transparent flame-retardant PC material of this invention simultaneously achieves UL94 V-0, no burn-through after ≥60 seconds of needle flame, and light transmittance ≥85% at a thickness of 1.0 mm. Furthermore, its composition is halogen-free and PFAS-free, complying with the EU (EU) 2021 / 1297 ban on PFAS.

[0046] 2. The flame-retardant PC material of this invention uses a novel phosphorus-nitrogen-silicon synergistic flame retardant with a POSS structure. This flame retardant integrates phosphorus, nitrogen, and silicon, resulting in a better synergistic flame-retardant effect. Specifically, the POSS cage structure rearranges at high temperatures (>400℃) to form a nano-ceramicized silica barrier, effectively isolating oxygen and inhibiting molten droplets, enabling a 1.0 mm thick PC sample to pass the UL 94 V-0 test, and significantly improving the needle flame resistance time to over 60 seconds; the phenyl structure precisely matches the polarity of the PC molecular chain through π-π stacking, preventing haze increase (transmittance >90%) and stress cracking caused by phase separation; phosphorus achieves dual-effect flame retardancy of "condensed phase-gas phase" through acid catalysis to char and PO· free radical quenching; nitrogen releases inert gas to dilute the concentration of combustibles; and silicon strengthens the density of the char layer (char residue >28% at 800℃). The flame retardant has good compatibility with PC, and while giving the material high flame retardancy, it can effectively maintain the impact strength and light transmittance of the matrix, with an impact strength retention rate of over 85%.

[0047] 3. The preparation method of the needle flame resistant transparent flame retardant PC material of the present invention is simple, requires little equipment, is easy to operate, and is easy to promote. Detailed Implementation

[0048] To better understand the above technical solutions, exemplary embodiments of the present invention will be described in more detail below through examples. Without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of those different embodiments or examples.

[0049] Example 1

[0050] Prepare phosphorus-nitrogen-silicon synergistic flame retardants containing POSS structures.

[0051] Under nitrogen protection, 5.768 g (0.005 mol) of T8 octaaminophenyl POSS, pre-dried at 80 °C under vacuum for 4 hours, was placed in a 500 ml three-necked flask and dissolved in 100 ml of anhydrous toluene at 60 °C to prepare a solution. Separately, 7.637 g of diphenylphosphonic acid, 0.074 g of EDC, and 0.048 g of HOBt were mixed in 50 ml of anhydrous toluene and slowly added dropwise to the POSS solution at a rate of 1 ml / min through a constant-pressure dropping funnel, maintaining the reaction temperature at 80 °C. After the addition was complete, the reaction was refluxed for 6 hours. Heating was stopped, and the reaction solution was cooled to 25 °C. The byproduct DCU (dicyclohexylurea) was removed by filtration, and the filter cake was washed three times with hot toluene (40 °C).

[0052] The filter cake was then redissolved in 150 ml of anhydrous toluene. The mixture was heated to 60°C, and then slowly added dropwise at a rate of 1 ml / min through a constant-pressure dropping funnel. The reaction was carried out under nitrogen protection and refluxed for 4 h. After the reaction was complete, the system was cooled to room temperature, and 100 ml of 1% NaHCO3 solution was added with stirring to quench the catalyst. The aqueous layer was discarded, and the organic phase was washed with water until neutral. The toluene solvent was then removed by vacuum distillation (40°C / 10 mmHg), yielding 13.335 g of a pale yellow solid product (90.0% yield). This product is the phosphorus-nitrogen-silicon synergistic flame retardant containing a POSS structure.

[0053] Its composition, after analysis, is as follows:

[0054]

[0055] Where R1 is .

[0056] Example 2

[0057] Prepare needle flame resistant transparent flame retardant polycarbonate material according to the following steps (three samples A1, A2 and A3 were prepared in total, and their composition and weight ratio are shown in Table 1 below).

[0058] (1) Dry the linear PC resin and branched PC resin at 120°C until the water content is less than 0.025%;

[0059] (2) According to the weight ratio, mix the linear PC resin, branched PC resin, sodium sulfonate flame retardant, potassium sulfonate flame retardant, organosilicon synergistic flame retardant, antioxidant, lubricant, talc powder and phosphorus-nitrogen-silicon synergistic flame retardant containing POSS structure evenly and set aside.

[0060] (3) The mixed raw materials are added to a twin-screw extruder for extrusion granulation (length-to-diameter ratio of 40-50) to obtain the needle flame resistant transparent flame retardant polycarbonate material; wherein the processing temperature of the twin-screw extruder is 260℃-270℃ and the screw speed is 260-280 RPM.

[0061] Table 1

[0062]

[0063] For the above samples A1, A2, and A3, tests such as needle flame test and vertical burning performance were conducted according to Appendix S (S.2 Flammability test for integrity of fireproof protective enclosures and fireproof baffles) in GB 4943.1-2022 and UL-94 standard. The test results are shown in Table 2 below.

[0064] Table 2

[0065]

[0066] As shown in Table 2, samples A1, A2, and A3 all achieved good results in all test items, meeting the requirements in both combustion performance and needle flame testing. Furthermore, while satisfying flame retardant performance and mechanical strength requirements, they also achieved high light transmittance and haze control. Among them, sample A2 achieved the best test results in all test items, indicating a more optimized formulation.

[0067] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make modifications, alterations, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A transparent flame-retardant polycarbonate material resistant to needle flames, characterized in that, The raw materials include the following parts by weight: 85-95 parts of polycarbonate resin, 0.1-0.5 parts of sulfonate flame retardant, 0.1-0.5 parts of organosilicon synergistic flame retardant, and 1-10 parts of phosphorus-nitrogen-silicon synergistic flame retardant containing a POSS structure. Optionally, it also includes antioxidants, lubricants, and / or inorganic fillers.

2. The needle-flame resistant transparent flame-retardant polycarbonate material according to claim 1, characterized in that, The polycarbonate resin comprises a mixture of linear polycarbonate and branched polycarbonate, wherein the content of branched polycarbonate is 10-30 parts by weight.

3. The needle-flame resistant transparent flame-retardant polycarbonate material according to claim 1, characterized in that, The sulfonate flame retardant is a mixture of sodium sulfonate flame retardant and potassium sulfonate flame retardant, with a weight ratio of 1:1.5 to 1:3.

6.

4. The needle-flame resistant transparent flame-retardant polycarbonate material according to claim 1, characterized in that, The phosphorus-nitrogen-silicon synergistic flame retardant containing the POSS structure has the structure shown in formula (1): Equation (1) ; Where R1 is Or -CH3, and each POSS structure contains 3 to 7 R1s. R2 is Or -CH3.

5. The needle-flame resistant transparent flame-retardant polycarbonate material according to claim 4, characterized in that, In equation (1), each POSS structure contains 3, 5, or 7 R1s. Furthermore, the two POSS structures are identical.

6. The needle-flame resistant transparent flame-retardant polycarbonate material according to claim 1, characterized in that, The phosphorus-nitrogen-silicon synergistic flame retardant containing the POSS structure is prepared by the following method: (1) Dissolve T8 aminophenyl POSS in a first solvent to form a first solution; mix diphenylphosphonic acid and the first catalyst in a second solvent to form a first mixture; (2) Under an inert atmosphere, the first mixture is added dropwise to the first solution and reacted at 60℃-100℃ for 3-8 hours. After the reaction is completed, the mixture is cooled, filtered, and washed to obtain the phosphorus-nitrogen POSS intermediate. (3) Dissolve the phosphorus-nitrogen POSS intermediate in a third solvent to form a second solution; mix the epoxy-terminated phenylsiloxane with the second catalyst in a fourth solvent to form a second mixture; (4) Under an inert atmosphere, the second mixture is added dropwise to the second solution and reacted at 60℃-80℃ for 2-6 hours. After the reaction is completed, the temperature is lowered, and an alkaline solution is added to quench the catalyst. The solvent is removed by separation, washing, and vacuum distillation to obtain the phosphorus-nitrogen-silicon synergistic flame retardant containing the POSS structure.

7. The needle-flame resistant transparent flame-retardant polycarbonate material according to claim 3, characterized in that, The sodium sulfonate flame retardant is sodium diphenyl sulfonate (NSS), sodium p-styrene sulfonate (NaPSS), sodium p-aminobenzene sulfonate (p-ABSA), or sodium 2,4,5-trichlorobenzene sulfonate (STB); the potassium sulfonate flame retardant is potassium diphenyl sulfonate (KSS), potassium perfluorobutyl sulfonate (PFBS), or potassium p-styrene sulfonate (KPSS).

8. The needle-flame resistant transparent flame-retardant polycarbonate material according to claim 1, characterized in that, The organosilicon synergistic flame retardant is a siloxane-based flame retardant, including phenylsiloxane, epoxy-modified siloxane, and polyether-modified siloxane.

9. The needle-flame resistant transparent flame-retardant polycarbonate material according to claim 1, characterized in that, The antioxidant is a hindered phenolic antioxidant, a phosphate ester antioxidant, and / or a thioester antioxidant; the lubricant is a fatty acid ester lubricant or a polyether lubricant; the inorganic filler is talc powder with a particle size (D50) of 0.6-3 μm.

10. The method for preparing the needle-flame resistant transparent flame-retardant polycarbonate material according to any one of claims 1-9, characterized in that, The method includes the following steps: (1) Dry the polycarbonate resin at 120℃-130℃ until the water content is less than 0.025%, and set aside for later use; (2) According to the weight ratio, the polycarbonate resin, sulfonate flame retardant, organosilicon synergistic flame retardant, phosphorus-nitrogen-silicon synergistic flame retardant with POSS structure, and optional antioxidant, lubricant and inorganic filler are mixed evenly. (3) The mixed raw materials are added to a twin-screw extruder for extrusion granulation to obtain the needle flame resistant transparent flame retardant polycarbonate material; wherein the processing temperature of the twin-screw extruder is 240℃-280℃ and the screw speed is 250-300RPM.

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