PFAS-free flame-retardant polycarbonate film and sheet and preparation method thereof

Abstract

The invention relates to the technical field of high polymer materials, and provides a PFAS-free flame-retardant polycarbonate film and sheet and a preparation method thereof. The thin film and the sheet are prepared from the following components in parts by weight: 80-95 parts of polycarbonate resin, 2-10 parts of a phosphazene flame retardant, 1-5 parts of an organic silicon flame retardant, 1-5 parts of inorganic filler, 0.1-2 parts of carbon nanotubes and 0-5 parts of other auxiliaries, and the thickness is less than or equal to 0.5 mm. The preparation method comprises the following steps: mixing the raw materials, carrying out melt blending granulation, and carrying out casting / film blowing / calendaring molding. According to the invention, PFAS is completely not contained, UL94-V0 flame retardance is realized under the condition of ultra-thin thickness, CTI is greater than or equal to 600V, the surface resistivity is 106-109 omega / sq, and the antistatic property is realized, so that the environment-friendly and multifunctional requirements of high-end electronic devices and new energy materials are met.

Description

Technical Field

[0001] This invention relates to the field of polymer materials technology, and in particular to a flame-retardant polycarbonate film and sheet without PFAS and a method for preparing the same. Background Technology

[0002] Polycarbonate is widely used in electronics, automotive parts, and building materials due to its excellent transparency, impact resistance, and heat resistance. However, polycarbonate itself is flammable, and flame-retardant modification is necessary in applications requiring high fire safety.

[0003] Currently, flame-retardant PC materials still face a series of severe challenges in their development. Among them, the performance imbalance of ultra-thin materials is particularly prominent. For films or sheets with a thickness of 0.5 mm or less, due to their large specific surface area, the migration rate of flame retardants is also relatively high, making it difficult to simultaneously meet the stringent requirements of high flame retardancy and high insulation. Specifically, they must meet the UL94-V0 rating requirement, i.e., self-extinguishing time of no more than 10 seconds after removal of the flame and no molten droplets, and also comply with the CTI≥600V Class 0 insulation standard.

[0004] Furthermore, environmental compliance risks cannot be ignored. Halogenated flame retardant systems, such as brominated polycarbonate, release highly toxic gases like dioxins when burned, a hazard already restricted by EU regulations such as RoHS. Halogen-free alternatives, however, rely excessively on PFAS (per- and polyfluoroalkyl substances). Due to their high CF bond energy (485 kJ / mol) and strong chemical inertness, PFAS are often used as highly effective flame retardant synergists (e.g., potassium perfluorobutyl sulfonate) or as antistatic coatings. However, PFAS exhibit extremely high environmental persistence, with half-lives reaching decades, and also possess bioaccumulation and potential toxicity, currently subject to strict control by global regulatory agencies. The EU REACH regulation includes PFOS / PFOA on its prohibited list; the US EPA released a PFAS action strategy in 2021, requiring mandatory testing of drinking water and industrial emissions; and China's "List of Key Controlled New Pollutants (2023 Edition)" also explicitly restricts several PFAS.

[0005] Under current technological conditions, there remains a significant technological gap in developing an ultrathin PC material that combines PFAS-free properties, high flame retardancy, high insulation, and stable antistatic properties. Using phosphorus-based flame retardants alone can lead to migration and precipitation problems at high concentrations, causing the CTI value to drop below 300V. Silicon-based flame retardants, on the other hand, rely on PFAS to improve char formation efficiency; otherwise, it is difficult to meet the stringent UL94-V0 flammability test requirements.

[0006] This application achieves synergistic optimization of the flame retardant, insulation, and antistatic properties of ultrathin polycarbonate materials through the synergistic effect of a ternary flame retardant system of phosphazene-organosilicon-inorganic filler and the conductivity of carbon nanotubes, without the presence of any PFAS. Summary of the Invention

[0007] This invention provides a PFAS-free flame-retardant polycarbonate film and sheet and its preparation method, in order to solve the environmental defects caused by the presence of PFAS in the prior art and the technical defects of the inability to coordinate the flame retardancy, insulation and antistatic properties of ultra-thin materials.

[0008] On one hand, the present invention provides a PFAS-free flame-retardant polycarbonate film and sheet, which are composed of the following components in parts by weight: 80-95 parts of polycarbonate resin; 2-10 parts of phosphazene flame retardant; 1-5 parts of organosilicon flame retardant; 1-5 parts of inorganic filler; 0.1-2 parts of carbon nanotubes; Other auxiliary agents: 0-5 parts; The other additives are selected from at least one of antioxidants, UV stabilizers, and lubricants; The thickness of the film or sheet is ≤0.5mm.

[0009] According to the present invention, a flame-retardant polycarbonate film and sheet without PFAS are provided, wherein the phosphazene flame retardant is an alkoxy or aryloxy substituted cyclotriphosphazene derivative.

[0010] According to the present invention, a flame-retardant polycarbonate film and sheet without PFAS are provided, wherein the organosilicon flame retardant is a polysiloxane compound.

[0011] According to the present invention, a flame-retardant polycarbonate film and sheet without PFAS are provided, wherein the inorganic filler is a metal oxide or a layered silicate.

[0012] According to the present invention, a flame-retardant polycarbonate film and sheet without PFAS are provided, wherein the carbon nanotubes are multi-walled carbon nanotubes.

[0013] On the other hand, the present invention also provides a method for preparing PFAS-free flame-retardant polycarbonate films and sheets, comprising the following steps: (1) Mix polycarbonate resin, phosphazene flame retardant, organosilicon flame retardant, inorganic filler, carbon nanotubes and other additives; (2) The mixture obtained in step (1) is melt-blended and extruded into granules in a twin-screw extruder; (3) The granulated material is made into a film or sheet through casting, blown film or calendering processes.

[0014] According to the present invention, a method for preparing PFAS-free flame-retardant polycarbonate films and sheets is provided, wherein the carbon nanotubes are added to the mixture by blending.

[0015] According to the present invention, a method for preparing flame-retardant polycarbonate films and sheets without PFAS is provided, wherein the carbon nanotubes can also be applied to the surface of the film or sheet by surface coating.

[0016] According to the method for preparing flame-retardant polycarbonate films and sheets without PFAS provided by the present invention, the melt blending temperature in step (2) is 260-280℃ and the screw speed is 200-400rpm.

[0017] According to the present invention, a method for preparing flame-retardant polycarbonate film and sheet without PFAS is provided, wherein the thickness of the film or sheet in step (3) is ≤0.5mm.

[0018] The PFAS-free flame-retardant polycarbonate film and sheet and their preparation method provided by this invention have the following advantages compared with the prior art: (1) The flame-retardant polycarbonate film and sheet without PFAS provided by the present invention and the preparation method thereof completely avoid the environmental risks of PFAS by using a compound system of halogen-free and fluorine-free phosphazene flame retardant and organosilicon flame retardant, solves the environmental compliance problem of flame retardant, and achieves the technical effect of complying with global green regulations.

[0019] (2) The flame-retardant polycarbonate film and sheet without PFAS provided by the present invention and the preparation method thereof, through the synergistic effect of phosphazene and organosilicon, combined with the improvement of CTI value by inorganic fillers, solves the technical problem that ultra-thin polycarbonate materials cannot simultaneously achieve UL94-V0 flame retardancy and CTI0 insulation, and achieves the outstanding effect of maintaining V0 flame retardancy and CTI value above 600V at a thickness of 0.10mm.

[0020] (3) The flame-retardant polycarbonate film and sheet without PFAS provided by the present invention and its preparation method solve the technical bottleneck of the surface resistivity being difficult to control stably in ultrathin materials by precisely adding carbon nanotubes and flexibly processing them, and achieve a high-precision effect of controlling resistivity across orders of magnitude by adjusting the carbon nanotube content.

[0021] (4) The flame-retardant polycarbonate film and sheet without PFAS provided by the present invention and the preparation method thereof solve the problem of performance fluctuation caused by uneven dispersion of flame retardant in ultra-thin materials by optimizing the melt blending process and molding process.

[0022] (5) The flame-retardant polycarbonate film and sheet without PFAS provided by the present invention and the preparation method thereof solve the problem that the existing technology needs to rely on PFAS additives to achieve multifunctional integration through the synergistic design of components and processes, and achieve the comprehensive technical effect of simultaneously meeting the requirements of flame retardancy, insulation, antistatic, high transparency and environmental protection in a single material system. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention are described clearly and completely below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0024] This invention provides a PFAS-free flame-retardant polycarbonate film and sheet, composed of the following components in parts by weight: 80-95 parts of polycarbonate resin, preferably 85-90 parts, more preferably 87-88 parts; 2-10 parts of phosphazene flame retardant, preferably 4-8 parts, more preferably 5-7 parts; 1-5 parts of organosilicon flame retardant, preferably 2-4 parts, more preferably 3.5-3.5 parts; The inorganic filler is 1-5 parts, preferably 2-4 parts, and more preferably 3.5-3.5 parts; The carbon nanotubes are 0.1-2 parts, preferably 0.5-1.5 parts, and more preferably 0.8-1.2 parts; Other additives: 0.1-5 parts, preferably 1.5-3.5 parts, more preferably 2-3 parts; The other additives are selected from at least one of antioxidants, UV stabilizers, and lubricants; The thickness of the film or sheet is ≤0.5mm.

[0025] According to the present invention, a flame-retardant polycarbonate film and sheet without PFAS are provided, wherein the phosphazene flame retardant is an alkoxy or aryloxy substituted cyclotriphosphazene derivative, preferably an aryloxy substituted cyclotriphosphazene derivative, and more preferably a hexaphenoxycyclotriphosphazene.

[0026] According to the present invention, a flame-retardant polycarbonate film and sheet without PFAS are provided, wherein the organosilicon flame retardant is a polysiloxane compound, preferably polydimethylsiloxane or polymethylphenylsiloxane, and more preferably polydimethylsiloxane.

[0027] According to the present invention, a flame-retardant polycarbonate film and sheet without PFAS are provided, wherein the inorganic filler is a metal oxide or layered silicate, preferably nano-silica or alumina.

[0028] According to the present invention, a flame-retardant polycarbonate film and sheet without PFAS are provided, wherein the carbon nanotubes are multi-walled carbon nanotubes.

[0029] On the other hand, the present invention also provides a method for preparing PFAS-free flame-retardant polycarbonate films and sheets, comprising the following steps: (1) Mix polycarbonate resin, phosphazene flame retardant, organosilicon flame retardant, inorganic filler, carbon nanotubes and other additives; (2) The mixture obtained in step (1) is melt-blended and extruded into granules in a twin-screw extruder; (3) The granulated material is made into a film or sheet through casting, blown film or calendering processes.

[0030] According to the present invention, a method for preparing PFAS-free flame-retardant polycarbonate films and sheets is provided, wherein the carbon nanotubes are added to the mixture by blending.

[0031] According to the present invention, a method for preparing flame-retardant polycarbonate films and sheets without PFAS is provided, wherein the carbon nanotubes can also be applied to the surface of the film or sheet by surface coating.

[0032] According to the present invention, the method for preparing flame-retardant polycarbonate film and sheet without PFAS is provided, wherein the melt blending temperature in step (2) is 260-280℃, preferably 265-275℃, and more preferably 268-272℃; and the screw speed is 200-400rpm, preferably 250-350rpm, and more preferably 280-320rpm.

[0033] According to the present invention, a method for preparing flame-retardant polycarbonate film and sheet without PFAS is provided, wherein the thickness of the film or sheet in step (3) is ≤0.5mm.

[0034] Example 1 Weigh out 880g of polycarbonate resin, 50g of hexaphenoxycyclotriphosphazene, 30g of polydimethylsiloxane, 30g of nano-silica, 8g of multi-walled carbon nanotubes, 2g of antioxidant 1010, and 5g of calcium stearate. Pour the above materials into a high-speed mixer and mix for 10 minutes to obtain a mixture; The mixture is poured into a twin-screw extruder and melt-blended at 270°C and 300 rpm, and then granulated. The granulated material is then cast into a 0.25mm film using a casting process.

[0035] Testing revealed that the PFAS-free flame-retardant polycarbonate film prepared in this embodiment has a UL94 flame retardancy rating of V0, a ​​CTI value of 625V, and a surface resistivity of 3.2 × 10⁻⁶. 8 Ω / sq, PFAS not detected.

[0036] Example 2 Weigh out 850g of polycarbonate resin, 70g of hexaphenoxycyclotriphosphazene, 35g of polymethylphenylsiloxane, 40g of alumina, 8g of multi-walled carbon nanotubes, and 3g of UV stabilizer UV-531. Pour the above materials into a high-speed mixer and mix for 10 minutes to obtain a mixture; The mixture is poured into a twin-screw extruder and melt-blended at 270°C and 300 rpm, and then granulated. The granulated material is then cast into a 0.30 mm film using a casting process.

[0037] Testing revealed that the PFAS-free flame-retardant polycarbonate film prepared in this embodiment has a UL94 flame retardancy rating of V0, a ​​CTI value of 630V, and a surface resistivity of 1.5 × 10⁻⁶. 7 Ω / sq, PFAS not detected.

[0038] Example 3 Weigh out 900g of polycarbonate resin, 45g of hexaphenoxycyclotriphosphazene, 25g of polydimethylsiloxane, and 30g of montmorillonite. Pour the above materials into a high-speed mixer and mix for 10 minutes to obtain a mixture; The mixture is poured into a twin-screw extruder and melt-blended at 270°C and 300 rpm, and then granulated. The granulated material is then processed into 0.20mm sheets using a casting process. Weigh 5g of multi-walled carbon nanotubes and prepare an aqueous dispersion of carbon nanotubes. Aqueous dispersions of carbon nanotubes are coated onto the surface of the sheet.

[0039] Testing revealed that the PFAS-free flame-retardant polycarbonate sheet prepared in this embodiment has a UL94 flame retardancy rating of V0, a ​​CTI value of 610V, and a surface resistivity of 6.8 × 10⁻⁶. 8 Ω / sq, PFAS not detected.

[0040] Example 4 Weigh out 870g of polycarbonate resin, 60g of hexaphenoxycyclotriphosphazene, 30g of polydimethylsiloxane, 25g of nano-silica, and 15g of multi-walled carbon nanotubes. Pour the above materials into a high-speed mixer and mix for 10 minutes to obtain a mixture; The mixture is poured into a twin-screw extruder and melt-blended at 270°C and 300 rpm, and then granulated. The granulated material is then cast into a 0.28 mm film using a casting process.

[0041] Testing revealed that the PFAS-free flame-retardant polycarbonate film prepared in this embodiment has a UL94 flame retardancy rating of V0, a ​​CTI value of 618V, and a surface resistivity of 8.4 × 10⁻⁶. 6 Ω / sq, PFAS not detected.

[0042] Example 5 Weigh out 880g of polycarbonate resin, 50g of hexaphenoxycyclotriphosphazene, 30g of polydimethylsiloxane, 30g of nano-silica, 8g of multi-walled carbon nanotubes, 2g of antioxidant 1010, and 5g of calcium stearate. Pour the above materials into a high-speed mixer and mix for 10 minutes to obtain a mixture; The mixture is poured into a twin-screw extruder and melt-blended at 270°C and 300 rpm, and then granulated. The granulated material is then cast into a 0.10 mm film using a casting process.

[0043] Testing revealed that the PFAS-free flame-retardant polycarbonate film prepared in this embodiment has a UL94 flame retardancy rating of V0, a ​​CTI value of 605V, and a surface resistivity of 2.9 × 10⁻⁶. 8 Ω / sq, PFAS not detected.

[0044] Comparative Example 1 Weigh out 880g of polycarbonate resin, 50g of hexaphenoxycyclotriphosphazene, 30g of polydimethylsiloxane, 30g of nano silica, 2g of antioxidant 1010, and 5g of calcium stearate. Pour the above materials into a high-speed mixer and mix for 10 minutes to obtain a mixture; The mixture is poured into a twin-screw extruder and melt-blended at 270°C and 300 rpm, and then granulated. The granulated material is then cast into a 0.25mm film using a casting process.

[0045] Testing revealed that the PFAS-free flame-retardant polycarbonate film prepared in this embodiment has a UL94 flame retardancy rating of V0, a ​​CTI value of 620V, and a surface resistivity >10. 12 Ω / sq, PFAS not detected.

[0046] Comparative Example 2 Weigh out 880g of polycarbonate resin, 50g of potassium perfluorobutyl sulfonate, 30g of polydimethylsiloxane, 30g of nano silica, 8g of multi-walled carbon nanotubes, 2g of antioxidant 1010, and 5g of calcium stearate. Pour the above materials into a high-speed mixer and mix for 10 minutes to obtain a mixture; The mixture is poured into a twin-screw extruder and melt-blended at 270°C and 300 rpm, and then granulated. The granulated material is then cast into a 0.25mm film using a casting process.

[0047] Testing revealed that the PFAS-free flame-retardant polycarbonate film prepared in this embodiment has a self-extinguishing time of 3 seconds, a UL94 flame retardancy rating of V0, a ​​CTI value of 600V, and a surface resistivity of 4.1 × 10⁻⁶. 8 Ω / sq, PFAS detected.

[0048] The above testing standards are UL94: ASTM D3801-2020 CTI: IEC60112:2020 Surface resistivity: ASTM D257-2014 PFAS: EPA 533-2020 The test results are shown in Table 1 below.

[0049] Table 1 Performance Test Summary

[0050] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A PFAS-free flame-retardant polycarbonate film and sheet, characterized in that, It consists of the following components in parts by weight: 80-95 parts of polycarbonate resin; 2-10 parts of phosphazene flame retardant; 1-5 parts of organosilicon flame retardant; 1-5 parts of inorganic filler; 0.1-2 parts of carbon nanotubes; Other auxiliary agents: 0-5 parts; The other additives are selected from at least one of antioxidants, UV stabilizers, and lubricants; The thickness of the film or sheet is ≤0.5mm.

2. The PFAS-free flame-retardant polycarbonate film and sheet according to claim 1, characterized in that, The phosphazene flame retardant is an alkoxy or aryloxy substituted cyclotriphosphazene derivative.

3. The PFAS-free flame-retardant polycarbonate film and sheet according to claim 1, characterized in that, The organosilicon flame retardant is a polysiloxane compound.

4. The PFAS-free flame-retardant polycarbonate film and sheet according to claim 1, characterized in that, The inorganic filler is a metal oxide or a layered silicate.

5. The PFAS-free flame-retardant polycarbonate film and sheet according to claim 1, characterized in that, The carbon nanotubes are multi-walled carbon nanotubes.

6. A method for preparing a PFAS-free flame-retardant polycarbonate film and sheet according to any one of claims 1-5, characterized in that, Includes the following steps: (1) Mix polycarbonate resin, phosphazene flame retardant, organosilicon flame retardant, inorganic filler, carbon nanotubes and other additives; (2) The mixture obtained in step (1) is melt-blended and extruded into granules in a twin-screw extruder; (3) The granulated material is made into a film or sheet through casting, blown film or calendering processes.

7. The method for preparing PFAS-free flame-retardant polycarbonate films and sheets according to claim 6, characterized in that, The carbon nanotubes are added to the mixture by blending.

8. The method for preparing PFAS-free flame-retardant polycarbonate films and sheets according to claim 6, characterized in that, The carbon nanotubes can also be applied to the surface of films or sheets by surface coating.

9. The method for preparing PFAS-free flame-retardant polycarbonate films and sheets according to claim 6, characterized in that, In step (2), the melt blending temperature is 260-280℃ and the screw speed is 200-400rpm.

10. The method for preparing PFAS-free flame-retardant polycarbonate films and sheets according to claim 6, characterized in that, The thickness of the film or sheet mentioned in step (3) is ≤0.5mm.

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