A new energy battery pack structural member flame-retardant porcelainized polymer alloy material and a preparation method thereof

Abstract

The present application relates to the technical field of flame-retardant polymer materials, and particularly relates to a kind of flame-retardant porcelain high polymer alloy material for new energy battery package structural member and a preparation method thereof.The method first deposits zinc borate on the surface of wet sericite, is treated by vinyl triethoxysilane, and then is kneaded with methyl vinyl silicone rubber raw rubber and platinum catalyst to obtain platinum-containing and uncrosslinked silicone rubber coated mica;then it is added into polybutylene terephthalate melt with insufficient amount of first-stage hydrogen-containing silicone oil from the same cylinder section, so that the shell gel is condensed and dispersed, the second-stage trigger is injected in the conveying section to make the shell bridge at the contact point, then aluminum diethyl phosphinate and glass powder are added, and the plate is obtained by calendering.The obtained material does not flow and burn through when on fire, the porcelain layer is continuous, the bending strength of the burning residue is improved, the notched impact strength is maintained, and the material can be hot-pressed into a shape.

Description

Technical Field

[0001] This invention relates to the field of flame-retardant polymer materials technology, specifically to a flame-retardant ceramic polymer alloy material for structural components of new energy battery packs and its preparation method. Background Technology

[0002] Structural components such as the top cover and module end plates of new energy battery packs need to be protected from flames and maintain structural integrity after being exposed to fire during battery thermal runaway. Polybutylene terephthalate and its alloys are commonly used substrates for these structural components due to their good electrical insulation, chemical resistance, and formability. To prevent the parts from flowing or developing holes after being exposed to fire and to leave a self-supporting ceramic layer, phosphorus-based flame retardants, lamellar silicate skeleton fillers, and low softening point fluxes are usually added to the substrate and then melt-blended before molding.

[0003] Patent CN122255565A discloses a ceramicized flame-retardant composite material made by one-time blending of polybutylene terephthalate with an organophosphorus flame retardant, chopped glass fiber, and a mixture of ceramic powders with multiple softening points. The ceramic powders with different softening points melt and bond in stages during the fire process. Patent CN122278148A discloses a ceramicized flame-retardant polybutylene terephthalate composite material made by combining a bio-based carbon source with a phosphorus flame retardant, a ceramicizing agent, and a flux. The carbon layer and the ceramicizing agent skeleton are wrapped by the molten flux. Patent CN119570154A discloses a ceramicizable plate made by cross-linking a thermoplastic matrix with an electron beam or peroxide, which makes it self-supporting when exposed to fire.

[0004] In the aforementioned process, the polybutylene terephthalate (PET) matrix essentially decomposes at 350–450°C, while the flux softens and binds the skeleton filler only above 550°C. The residue in the temperature range between these two is loose powder, prone to cracking and peeling. To ensure a continuous ceramic layer forms in this range, the total amount of skeleton filler and flux must be increased, or multiple gradient fluxes must be applied. The total inorganic component content often needs to reach over 30%, resulting in a decrease in the notched impact strength of the part. Exchanging overall matrix cross-linking for shape retention under fire results in the loss of thermoplastic processability, rendering the sheet unsuitable for hot pressing. The challenge of maintaining the material's shape and forming a continuous, self-supporting ceramic layer after matrix decomposition, while preserving the impact toughness and hot pressing properties of the part, without increasing the total inorganic component content, remains unresolved by current technology. Summary of the Invention

[0005] When existing polybutylene terephthalate-based flame-retardant ceramic materials are exposed to fire, the ceramic layer becomes loose and unable to support itself in the temperature range between matrix decomposition and flux softening. Increasing the amount of ceramic filler will reduce the notched impact strength of the part, and the cross-linked matrix loses its hot-pressing moldability while maintaining its shape. It is difficult to achieve all three goals at the same time.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: a method for preparing a flame-retardant ceramic polymer alloy material for structural components of new energy battery packs, comprising the following steps:

[0007] (1) Disperse wet sericite powder in water, add boric acid and zinc oxide, and deposit zinc borate on the mica surface under heating and stirring. Filter, wash and dry to obtain zinc borate deposited mica. Treat the zinc borate deposited mica with the hydrolysate of vinyltriethoxysilane, and then knead it with methyl vinyl silicone rubber raw rubber, platinum catalyst and hydrosilylation inhibitor to coat the mica surface with raw rubber. Chop it to obtain platinum-containing and non-crosslinked silicone rubber coated mica. The silicone rubber coated mica does not contain hydrogen-containing silicone oil.

[0008] (2) Polybutylene terephthalate dried to a moisture content of no more than 0.02% and toughening agent are added and melted through the main feed port of the twin-screw extruder; the silicone rubber-coated mica obtained in step (1) is added to the melt through the side feed port after the melting section, and at the same time, the first section of hydrogen-containing silicone oil is injected into the barrel section where the side feed port is located, so that the silicone rubber shell gels and disperses in the subsequent melt mixing section; the ratio of the amount of Si-H in the first section of hydrogen-containing silicone oil to the vinyl equivalent is 0.4 to 0.8, and the vinyl equivalent is calculated according to the silicone rubber-coated mica added in step (2), which is the sum of the amount of vinyl in the methyl vinyl silicone rubber raw rubber contained in the silicone rubber-coated mica and 20% of the amount of vinyltriethoxysilane contained therein, and the content of raw rubber and vinyltriethoxysilane is converted according to the feeding in step (1);

[0009] (3) A second triggering agent is injected into the conveying section after the melting and mixing section to bridge the contact points of the silicone rubber shells. The second triggering agent is hydrogen-containing silicone oil or a solution of hydrogen-containing MQ silicone resin and hydrogen-containing silicone oil. The dosage of the second triggering agent based on Si-H is 0.8 to 1.5 mol per 100 kg of mixed material. After the injection of the second triggering agent, aluminum diethylphosphinate, low softening point borosilicate glass powder, phosphite antioxidant and polytetrafluoroethylene are added through the side feed port.

[0010] (4) The melt is extruded through a T-die and calendered into a sheet to obtain the flame-retardant ceramic polymer alloy material;

[0011] The silicone rubber-coated mica accounts for 20% to 33% of the total mass of the compound, and the total mass of the compound is the sum of the masses of all components added in steps (2) and (3); the mass ratio of methyl vinyl silicone rubber raw rubber to mica in the silicone rubber-coated mica is 0.5 to 1.2.

[0012] Further, in step (1), the amount of zinc oxide and boric acid used is 12% to 25% of the mica mass based on the production of 2ZnO·3B2O3·3.5H2O, and the amount of vinyltriethoxysilane used is 0.8% to 2% of the mica mass.

[0013] Further, in step (1), zinc borate is deposited at 88-96°C for 4-6 hours; the platinum catalyst is 5-20 ppm of the mass of the methyl vinyl silicone rubber raw material, the hydrosilylation inhibitor is 0.05%-0.2% of the mass of the methyl vinyl silicone rubber raw material, and the kneading is carried out at 60-80°C for 30-60 minutes.

[0014] Further, based on the total mass of the compound, polybutylene terephthalate (PET) comprises 45%–56%, toughening agent 2%–4%, aluminum diethylphosphinate 8%–13%, low-softening-point borosilicate glass powder 4%–10%, phosphite antioxidant 0.1%–0.3%, and polytetrafluoroethylene (PTFE) 0.2%–0.5%. The toughening agent is an ethylene-methyl acrylate-glycidyl methacrylate copolymer. The compound may also contain 1%–2.5% epoxy-modified silicone oil, 0.1%–0.3% hindered phenolic antioxidant, and 0.1%–0.3% pentaerythritol stearate. The low-softening-point borosilicate glass powder refers to borosilicate glass powder with a melting temperature not exceeding 550°C.

[0015] Furthermore, in step (2), the temperature of the section where the silicone rubber-coated mica and the first section of hydrogen-containing silicone oil are added, as well as the temperature of the melting and mixing section, is 245–255°C, and the screw speed is 250–350 r / min; in step (3), the temperature of the conveying section is 245–255°C, and the residence time of the material from the second section trigger injection point to the die head is 40–80 s. The first section of hydrogen-containing silicone oil can be prepared as a dimethyl silicone oil solution for injection.

[0016] Further, in step (3), the second trigger is a solution of hydrogen-containing MQ silicone resin and hydrogen-containing silicone oil, wherein the hydrogen-containing MQ silicone resin accounts for 45% to 70% of the mass of the solution.

[0017] Furthermore, in step (4), the thickness of the calendered board is 2-3 mm, and the temperature of the calendering roller is 60-100℃.

[0018] Furthermore, it also includes step (5): heating the plate obtained in step (4) to 235-245°C, placing it in a mold with a mold temperature of 80-120°C, and hot-pressing it into a battery pack structural component at 1-3 MPa. The nominal strain at the maximum stretch of the formed component does not exceed 30%. The nominal strain is calculated based on the thickness of the plate before forming and the thickness of the formed component at that point, i.e., nominal strain = (thickness of plate before forming / thickness of the formed component at that point - 1) × 100%.

[0019] The present invention also provides a flame-retardant ceramic polymer alloy material for new energy battery pack structural components prepared by the above preparation method, and the application of the material in the preparation of the top cover or module end plate of the new energy battery pack.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) The polybutylene terephthalate-based sheet obtained in this invention does not flow or drip when exposed to fire, and does not burn through after being burned by a spray gun for 600 seconds. It forms a continuous and self-supporting ceramic layer from the mid-temperature zone after the matrix decomposes, which slows down the spread of flames to the outside of the battery pack during thermal runaway. This is because the platinum-containing uncrosslinked silicone rubber shell is pre-coated on zinc borate deposited mica, which is first gelled and dispersed in the melt, and then bridged at the contact point by a second triggering agent, and then fixed by calendering to form a mica templated shell network.

[0022] (2) The material obtained by this invention can be hot-pressed into structural parts such as battery pack top cover and module end plate under a pressure not exceeding 3MPa. The molded parts do not drip in the 350℃ sag test. It does not require irradiation or peroxide crosslinking. It can still be injection molded after pelleting, taking into account the shape retention, formability and reprocessability. This is because the network only exists between the filler shell layers and the matrix itself is not crosslinked.

[0023] (3) When the total inorganic component of the material obtained by the present invention is not higher than 30%, the bending strength of the residue after burning at 1000℃ reaches more than 1.9MPa, the shrinkage of the residue is reduced, the ceramic layer after being burned maintains its shape and continues to bear the load, and the structural components can still maintain isolation in the later stage of the fire. This is because zinc borate is deposited in situ on the surface of mica and covered by the shell layer, and a bonding phase is formed at the contact point of the skeleton when it is burned.

[0024] (4) The notched impact strength of the material obtained by this invention is not lower than that of the polybutylene terephthalate / polycarbonate alloy-based ceramic material prepared by blending phosphorus-based flame retardants, flake silicate fillers and low softening point fluxes. The tensile strength is maintained at more than 85% of that of such materials, and the vertical burning reaches V-0 level, which meets the flame retardant and impact resistance requirements of battery pack structural components. This is because the mica is coated by the cross-linked silicone rubber shell and connected to the matrix by the toughening agent. The phosphorus-containing component is added only after bridging triggering, and does not interfere with the platinum in the shell.

[0025] (5) When the present invention uses a solution of hydrogen-containing MQ silicone resin and hydrogen-containing silicone oil as the second-stage trigger, compared with using hydrogen-containing silicone oil as the second-stage trigger, the flexural strength of the residues after burning at 600°C and 1000°C is further improved, the linear shrinkage rate is further reduced, and the self-supporting time of the part after being exposed to fire is longer. The reason is that the bridging nodes are enriched with Q units, and the nodes remain connected during the conversion of siloxane to silicon dioxide. Detailed Implementation

[0026] The polybutylene terephthalate (PBT) used in the preparation examples, embodiments, and comparative examples was sourced from Changchun Artificial Resin Factory Co., Ltd., traded under the name LONGLITE, grade 1100-211M, with an intrinsic viscosity of 1.0 dL / g; the methyl vinyl silicone rubber raw material was sourced from Dongjue Organosilicon Group Co., Ltd., grade 110-3, with a vinyl chain molar fraction of 0.19%–0.24%, and the batch used was 0.20%; the hydrogen-containing silicone oil was sourced from Zhejiang Kaister New Material Co., Ltd., grade 202, with an active hydrogen mass fraction of [missing information]. The platinum content is not less than 1.58%, and the batch used has a platinum content of 1.58%; the platinum catalyst solution is PT-3000 from Guangzhou Silicon Friends New Materials Technology Co., Ltd., which is a silicone oil solution of Karstedt type platinum complex with a platinum mass fraction of 0.3%; the hydrosilylation inhibitor is 1-ethynyl-1-cyclohexanol, industrial grade, with a purity of not less than 98%; the epoxy-modified silicone oil is from Shin-Etsu Chemical, brand name KF-101, with an epoxy equivalent of 350 g / mol; the toughening agent is Arkema's ethylene-methyl acrylate-glycidyl methacrylate copolymer, brand name LOTADER. AX8900 has a glycidyl methacrylate content of 8%; wet-process sericite powder is sourced from Chuzhou Gerui Mining Co., Ltd., grade GH-102, with a D50 not exceeding 13μm; glass powder is low softening point borosilicate glass powder from Guangzhou Geliner New Materials Co., Ltd., grade D250, with a melting temperature of 500℃ and a D50 of 5-10μm; aluminum diethylphosphinate is sourced from Clariant, trade name Exolit, grade OP1230; polytetrafluoroethylene is coated polytetrafluoroethylene anti-dripping agent from Guangzhou Shangneng Innovation Materials Co., Ltd., grade SN3306; antioxidant 1010 (hereinafter referred to as hindered phenolic antioxidant) and antioxidant 168 (hereinafter referred to as phosphite antioxidant) are sourced from BASF, grade Irganox 1010 and Irgafos. 168; The hydrogen content of the hydrogen-containing MQ silicone resin is 0.7%, the molar ratio of M units to Q units is 0.7, it is a viscous liquid at 25℃, and it is miscible with hydrogen-containing silicone oil; The methyl MQ silicone resin is from Hubei Longsheng Sihai New Material Co., Ltd., brand name SH-5201P, it is a solid powder, and the molar ratio of M units to Q units is 0.6~0.9; Zinc borate is ZB-01 from Hubei Xingyan New Material Technology Co., Ltd., with the composition 2ZnO·3B2O3·3.5H2O; Polycarbonate is from Wanhua Chemical, trade name Clarnate, brand name A1225; Melamine polyphosphate is from Zhenjiang Xingxing Flame Retardant Co., Ltd.; Triallyl isocyanurate is industrial grade, with a purity of not less than 98%.

[0027] In the following examples, the amount of hydrogen-containing silicone oil used in the first stage is calculated based on the molar ratio of Si-H to vinyl equivalent. The vinyl equivalent is calculated based on the silicone rubber overmolding mica actually added to the melt in step (2), which is the sum of 20% of the amount of vinyl in the methyl vinyl silicone rubber raw material contained in the silicone rubber overmolding mica and the amount of vinyltriethoxysilane contained therein. The content of raw material and silane is converted according to the feeding of the preparation example. The molar fraction of vinyl chain segments in the raw material and the mass fraction of active hydrogen in the hydrogen-containing silicone oil are calculated based on the values ​​of the batches used above. The hydrogen-containing silicone oil or the solution of hydrogen-containing MQ silicone resin and hydrogen-containing silicone oil injected in the second stage is referred to as the second stage trigger. Its amount based on Si-H is calculated based on the mass fraction of active hydrogen in the hydrogen-containing silicone oil and the hydrogen content of the hydrogen-containing MQ silicone resin, based on 100 kg of compound. The total mass of the compound is the sum of the masses of all components added at the main feed port, side feed port and liquid injection port. The inorganic components described in this invention refer to mica, zinc borate, and low-softening-point borosilicate glass powder, the total amount of which is based on the total mass of the compound. The low-softening-point borosilicate glass powder refers to borosilicate glass powder with a melting temperature not exceeding 550℃. In the examples used, the melting temperature of grade D250 is 500℃. The nominal strain at the point of maximum tension in the hot-pressed part is calculated by reducing the thickness at that point, i.e., nominal strain = (thickness of sheet material before molding / thickness of the molded part at that point - 1) × 100%, and the thickness of the molded part at that point is measured using a micrometer.

[0028] Preparation Example 1:

[0029] Step (1): Add 11.8 kg of wet-process sericite powder to a jacketed reactor containing 35.4 kg of deionized water, stir and disperse at 300 r / min, add 2.22 kg of boric acid, heat to 92℃ and stir until the boric acid dissolves. Mix 885 g of zinc oxide with 2.36 kg of deionized water to form a slurry, add it to the reactor within 30 min, and keep it at 92℃ with stirring for 5 h to obtain a zinc borate-deposited mica suspension.

[0030] Step (2): Filter the suspension while it is hot, wash the filter cake twice with deionized water at 60℃ (11.8kg each time) until the conductivity of the filtrate is not higher than 200μS / cm, dry the filter cake at 110℃ for 8h, crush it and pass it through a 200-mesh sieve to obtain zinc borate deposited mica.

[0031] Preparation Example 2:

[0032] 126 g of vinyltriethoxysilane was added to a mixture of 810 g of ethanol and 90 g of deionized water. The pH was adjusted to 4 with 1.5 g of acetic acid, and the mixture was stirred for 30 min to obtain a silane hydrolysate. 12.3 kg of zinc borate deposited mica obtained in Preparation Example 1 was added to a kneader. The silane hydrolysate was sprayed in at 80 °C and mixed for 30 min until the ethanol was removed and the material was in a loose powder form, thus obtaining silane-treated zinc borate deposited mica.

[0033] Preparation Example 3:

[0034] Take 9600g of silane-treated zinc borate deposited mica obtained in Preparation Example 2 and add it to a kneader. Add 6530g of methyl vinyl silicone rubber raw rubber, 21.8g of platinum catalyst solution and 6.5g of hydrosilylation inhibitor 1-ethynyl-1-cyclohexanol. Knead at 70°C for 45min until there are no visible raw rubber lumps in the material. After cooling, chop and pass through a 10-mesh sieve to obtain silicone rubber-coated mica.

[0035] Preparation Example 4:

[0036] Except for replacing the zinc borate deposited mica obtained in Preparation Example 1 with 800g of silane to treat the zinc borate deposited mica, and changing the amounts of methyl vinyl silicone rubber raw rubber, platinum catalyst solution and 1-ethynyl-1-cyclohexanol to 550g, 1.8g and 0.6g respectively, the rest was the same as in Preparation Example 3, and untreated silicone rubber-coated mica was obtained.

[0037] Preparation Example 5:

[0038] Step (1): Add 8.4g of vinyltriethoxysilane to a mixture of 54g of ethanol and 6g of deionized water, adjust the pH to 4 with 0.1g of acetic acid, and stir for 30min to obtain silane hydrolysate. Add 700g of wet-process sericite powder to a kneader, spray the silane hydrolysate into it at 80℃ and mix for 30min until the ethanol is removed and the material is in a loose powder form, thus obtaining silane-treated mica.

[0039] Step (2): Add 560g of methyl vinyl silicone rubber raw rubber, 1.9g of platinum catalyst solution and 0.6g of 1-ethynyl-1-cyclohexanol to the kneader, knead at 70℃ for 45min, cool, chop and pass through a 10-mesh sieve to obtain silicone rubber-coated mica without zinc borate.

[0040] Preparation Example 6:

[0041] Except that the amount of silane-treated zinc borate deposited mica was changed to 760g, and the amounts of methyl vinyl silicone rubber raw rubber, platinum catalyst solution and 1-ethynyl-1-cyclohexanol were changed to 520g, 1.7g and 0.5g respectively, and 2.5g of methyl MQ silicone resin was added at the same time as the raw rubber, the rest was the same as in Preparation Example 3, and silicone rubber-coated mica with methyl MQ silicone resin in the shell was obtained.

[0042] Example 1:

[0043] Step (1): Dry the PBT resin at 120℃ for 4 hours until the moisture content is no higher than 0.02%. Mix 2585g of dried PBT resin, 150g of toughening agent, 75g of epoxy modified silicone oil, 7.5g of hindered phenolic antioxidant and 10g of pentaerythritol stearate, and add the mixture through the main feed port of a twin-screw extruder (length-to-diameter ratio 44, ten zones in the barrel, with one side feed port in zones four and nine, and one liquid injection port in zones four, five and eight. In this example, the liquid injection port in zone five is blocked and not used, and a vacuum exhaust port is provided in zone ten). The feeding rate is 10kg / h, the temperature in zones one to three is 245℃, and the screw speed is 300r / min.

[0044] Step (2): Take 1250g of mica for silicone rubber coating obtained in Preparation Example 3, add melt through the feed port of Zone 4, and at the same time inject 8.3g of dimethyl silicone oil solution containing hydrogen silicone oil (mass fraction of hydrogen silicone oil is 10%) through the liquid injection port of Zone 4. The temperature of Zone 4 to Zone 7 is 250℃.

[0045] Step (3): Inject 3.5g of hydrogen-containing silicone oil through the liquid injection port in zone 8. The temperature from zone 8 to zone 10 is 250℃. The residence time of the material from zone 8 to the head of the machine is 50s. Add 550g of aluminum diethylphosphinate, 350g of glass powder, 7.5g of phosphite antioxidant and 15g of polytetrafluoroethylene through the side feed port in zone 9. Exhaust the gas in zone 10 with a vacuum of -0.08MPa.

[0046] Step (4): The melt is extruded through a T-die at 250°C and rolled into a 2.5mm thick sheet by a three-roll calender (roll temperature 80°C) to obtain a flame-retardant ceramic polymer alloy sheet.

[0047] Step (5): Cut the sheet into blanks with a length of 300mm and a width of 230mm, place them flat on a polytetrafluoroethylene coated steel plate, heat them in an oven to a temperature of 240℃ and keep them warm for 2 minutes. After removing the blanks along with the steel plate, immediately transfer them into a mold with a temperature of 100℃ and hot press them at 2MPa to form a tray-shaped top cover specimen with a length of 250mm, a width of 180mm, a depth of 20mm and a bottom corner radius of 10mm. After holding the pressure for 60s, demold the specimen to obtain a flame-retardant ceramic polymer alloy material component for battery pack structural parts.

[0048] Example 2:

[0049] Step (1): Dry the PBT resin at 120℃ for 4 hours until the moisture content is no higher than 0.02%. Mix 2734g of dried PBT resin, 190g of toughening agent, 120g of epoxy modified silicone oil, 14g of hindered phenolic antioxidant and 14g of pentaerythritol stearate, and add it through the main feed port of the same twin-screw extruder as in Example 1. The feeding rate is 11kg / h, the temperature of zone 1 to zone 3 is 245℃, and the screw speed is 340r / min.

[0050] Step (2): Take 1050g of mica for silicone rubber coating obtained in Preparation Example 3, add melt through the feed port of Zone 4, and at the same time inject 5.2g of dimethyl silicone oil solution containing hydrogen silicone oil (mass fraction of hydrogen silicone oil is 10%) through the liquid injection port of Zone 4. The temperature of Zone 4 to Zone 7 is 246℃.

[0051] Step (3): Inject 2.7g of hydrogen-containing silicone oil through the liquid injection port in zone 8. The temperature from zone 8 to zone 10 is 246℃. The residence time of the material from zone 8 to the head of the machine is 45s. Add 620g of aluminum diethylphosphinate, 220g of glass powder, 14g of phosphite antioxidant and 24g of polytetrafluoroethylene through the side feed port in zone 9. Exhaust the gas in zone 10 with a vacuum of -0.08MPa.

[0052] Step (4): The melt is extruded through a T-die at 250°C and rolled into a 3mm thick sheet by a three-roll calender (roll temperature 65°C) to obtain a flame-retardant ceramic polymer alloy sheet.

[0053] Step (5): Cut the sheet into blanks with a length of 300mm and a width of 230mm, place them flat on a polytetrafluoroethylene coated steel plate, heat them in an oven to a temperature of 236℃ and keep them warm for 2 minutes. After removing the blanks along with the steel plate, immediately transfer them into a mold with a temperature of 85℃ and hot press them at 1.2MPa to form a tray-shaped cover specimen similar to that in Example 1. After holding the pressure for 60s, demold them to obtain flame-retardant ceramic polymer alloy material parts for battery pack structural components.

[0054] Example 3:

[0055] Step (1): Dry the PBT resin at 120℃ for 4 hours until the moisture content is no higher than 0.02%. Mix 2306g of dried PBT resin, 110g of toughening agent, 55g of epoxy modified silicone oil, 6g of hindered phenolic antioxidant and 6g of pentaerythritol stearate, and add it through the main feed port of the same twin-screw extruder as in Example 1. The feeding rate is 7kg / h, the temperature of zone 1 to zone 3 is 245℃, and the screw speed is 260r / min.

[0056] Step (2): Take 1600g of mica coated with silicone rubber obtained in Preparation Example 3, add melt through the feed port of Zone 4, and at the same time inject 13.2g of dimethyl silicone oil solution containing hydrogen silicone oil (mass fraction of hydrogen silicone oil is 10%) through the liquid injection port of Zone 4. The temperature of Zone 4 to Zone 7 is 254℃.

[0057] Step (3): Inject 4.5g of hydrogen-containing silicone oil through the liquid injection port in zone 8. The temperature from zone 8 to zone 10 is 254℃. The residence time of the material from zone 8 to the head of the machine is 75s. Add 420g of aluminum diethylphosphinate, 480g of glass powder, 6g of phosphite antioxidant and 11g of polytetrafluoroethylene through the side feed port in zone 9. Exhaust the gas in zone 10 with a vacuum of -0.08MPa.

[0058] Step (4): The melt is extruded through a T-die at 250°C and rolled into a 2mm thick sheet by a three-roll calender (roll temperature 95°C) to obtain a flame-retardant ceramic polymer alloy sheet.

[0059] Step (5): Cut the sheet into blanks with a length of 300mm and a width of 230mm, place them flat on a polytetrafluoroethylene coated steel plate, heat them in an oven to a temperature of 244℃ and keep them warm for 2 minutes. After removing the blanks along with the steel plate, immediately transfer them into a mold with a temperature of 115℃ and hot press them at 2.8MPa to form a tray-shaped cover specimen similar to that in Example 1. After holding the pressure for 60s, demold them to obtain flame-retardant ceramic polymer alloy material parts for battery pack structural components.

[0060] Example 4:

[0061] Step (1): Dry the PBT resin at 120℃ for 4 hours until the moisture content is no higher than 0.02%. Mix 2585g of dried PBT resin, 150g of toughening agent, 75g of epoxy modified silicone oil, 7.5g of hindered phenolic antioxidant and 10g of pentaerythritol stearate, and add it through the main feed port of the same twin-screw extruder as in Example 1. The feeding rate is 10kg / h, the temperature of zone one to zone three is 245℃, and the screw speed is 300r / min.

[0062] Step (2): Take 1250g of mica for silicone rubber coating obtained in Preparation Example 3, add melt through the feed port of Zone 4, and at the same time inject 8.3g of dimethyl silicone oil solution containing hydrogen silicone oil (mass fraction of hydrogen silicone oil is 10%) through the liquid injection port of Zone 4. The temperature of Zone 4 to Zone 7 is 250℃.

[0063] Step (3): Stir 2.4g of hydrogen-containing MQ silicone resin and 2.4g of hydrogen-containing silicone oil at 60℃ until dissolved to obtain the second stage trigger agent, which is injected through the liquid injection port of zone 8. The temperature from zone 8 to zone 10 is 250℃, and the residence time of the material from zone 8 to the head is 50s. Add 550g of aluminum diethylphosphinate, 350g of glass powder, 7.5g of phosphite antioxidant and 15g of polytetrafluoroethylene through the side feed port of zone 9. Vacuum exhaust at -0.08MPa in zone 10.

[0064] Step (4): The melt is extruded through a T-die at 250°C and rolled into a 2.5mm thick sheet by a three-roll calender (roll temperature 80°C) to obtain a flame-retardant ceramic polymer alloy sheet.

[0065] Step (5): Cut the sheet into blanks with a length of 300mm and a width of 230mm, place them flat on a polytetrafluoroethylene coated steel plate, heat them in an oven to a temperature of 240℃ and keep them at that temperature for 2 minutes. After removing the blanks along with the steel plate, immediately transfer them into a mold with a temperature of 100℃ and hot press them at 2MPa to form a tray-shaped cover specimen similar to that in Example 1. After holding the pressure for 60 seconds, demold the specimen to obtain a flame-retardant ceramic polymer alloy material component for the battery pack structure.

[0066] Example 5:

[0067] Step (1): Dry the PBT resin at 120℃ for 4 hours until the moisture content is no higher than 0.02%. Mix 2306g of dried PBT resin, 110g of toughening agent, 55g of epoxy modified silicone oil, 6g of hindered phenolic antioxidant and 6g of pentaerythritol stearate, and add it through the main feed port of the same twin-screw extruder as in Example 1. The feeding rate is 7kg / h, the temperature of zone 1 to zone 3 is 245℃, and the screw speed is 260r / min.

[0068] Step (2): Take 1600g of mica coated with silicone rubber obtained in Preparation Example 3, add melt through the feed port of Zone 4, and at the same time inject 13.2g of dimethyl silicone oil solution containing hydrogen silicone oil (mass fraction of hydrogen silicone oil is 10%) through the liquid injection port of Zone 4. The temperature of Zone 4 to Zone 7 is 254℃.

[0069] Step (3): 4.6g of hydrogen-containing MQ silicone resin and 2.5g of hydrogen-containing silicone oil are stirred at 60℃ until dissolved to obtain the second stage trigger agent, which is injected through the liquid injection port of zone 8. The temperature from zone 8 to zone 10 is 254℃, and the residence time of the material from zone 8 to the head is 75s. 420g of aluminum diethylphosphinate, 480g of glass powder, 6g of phosphite antioxidant and 11g of polytetrafluoroethylene are added through the side feed port of zone 9. Zone 10 is vented under vacuum of -0.08MPa.

[0070] Step (4): The melt is extruded through a T-die at 250°C and rolled into a 2.8mm thick sheet by a three-roll calender (roll temperature 95°C) to obtain a flame-retardant ceramic polymer alloy sheet.

[0071] Step (5): Cut the sheet into blanks with a length of 300mm and a width of 230mm, place them flat on a polytetrafluoroethylene coated steel plate, heat them in an oven to a temperature of 244℃ and keep them warm for 2 minutes. After removing the blanks along with the steel plate, immediately transfer them into a mold with a temperature of 115℃ and hot press them at 2.8MPa to form a tray-shaped cover specimen similar to that in Example 1. After holding the pressure for 60s, demold them to obtain flame-retardant ceramic polymer alloy material parts for battery pack structural components.

[0072] Comparative Example 1:

[0073] 2350g of PBT resin and 600g of polycarbonate were dried at 120℃ for 4 hours. The dried resins were then mixed with 500g of aluminum diethylphosphinate, 150g of melamine polyphosphate, 650g of wet-process sericite powder, 350g of glass powder, 125g of zinc borate, 225g of toughening agent, 15g of polytetrafluoroethylene, 7.5g of hindered phenolic antioxidant, 7.5g of phosphite antioxidant, 10g of zinc dihydrogen phosphate, and 10g of pentaerythritol stearate. The mixture was fed into the main feed port of the same twin-screw extruder as in Example 1, at a feed rate of 10kg / h. The temperature in zone 1 was 230℃, and the temperatures in zones 2 to 10 were 250℃. The screw speed was 350r / min, and zone 10 was degassed under a vacuum of -0.08MPa. The melt is extruded through a T-die at 250°C and calendered into a 2.5mm thick sheet by a three-roll calender (roll temperature 80°C) to obtain a PBT / polycarbonate alloy-based flame-retardant ceramic sheet.

[0074] Comparative Example 2:

[0075] Except for the following changes, the raw materials, dosages, and preparation conditions were the same as in Example 1: silicone rubber-coated mica was not used; 505g of methyl vinyl silicone rubber raw material was mixed with 0.5g of 1-ethynyl-1-cyclohexanol and cut into strips, then added along with PBT resin through the main feed port; 743g of silane-treated zinc borate deposited mica obtained in Preparation Example 2 was added through the fourth-zone side feed port, and simultaneously 8.3g of a dimethyl silicone oil solution containing hydrogen silicone oil (10% by mass) and 3.5g of hydrogen silicone oil were injected through the fourth-zone liquid injection port; a mixture of 1.7g of platinum catalyst solution and 15g of dimethyl silicone oil was injected through the fifth-zone liquid injection port, and no hydrogen silicone oil was injected into the eighth zone. Flame-retardant ceramic sheets containing silicone rubber in dispersed particle form were obtained.

[0076] Comparative Example 3:

[0077] Except for the absence of hydrogen-containing silicone oil in zone 8, the raw materials, dosages, and preparation conditions were the same as in Example 1, resulting in flame-retardant ceramic sheets.

[0078] Comparative Example 4:

[0079] Except for adding 3.5g of hydrogen-containing silicone oil to zone four and injecting it simultaneously with the dimethyl silicone oil solution containing hydrogen-containing silicone oil through the liquid injection port of zone four, and not injecting it into zone eight, the other raw materials, dosages and preparation conditions are the same as in Example 1, and flame-retardant ceramic plates are obtained.

[0080] Comparative Example 5:

[0081] Except for changing the amount of PBT resin to 2485g and adding 100g of triallyl isocyanurate along with the PBT resin through the main feed port, the other raw materials, amounts and preparation conditions were the same as those in Comparative Example 2. The resulting plate was irradiated with an electron beam (electron energy 10MeV, absorbed dose 100kGy) to obtain an electron beam crosslinked flame-retardant ceramic plate.

[0082] Comparative Example 6:

[0083] Except for replacing the silicone rubber-coated mica with 1142g of the zinc borate-free silicone rubber-coated mica obtained in Example 5, and adding 108g of zinc borate along with aluminum diethylphosphinate through the feed port on the ninth side, the other raw materials, amounts, and preparation conditions were the same as in Example 1, and flame-retardant ceramic sheets were obtained.

[0084] Comparative Example 7:

[0085] Except for replacing the silicone rubber-coated mica with 1250g of untreated silicone rubber-coated mica obtained in Example 4, and replacing the dimethyl silicone oil solution containing hydrogen silicone oil injected in the fourth zone with 5.2g, the other raw materials, amounts and preparation conditions were the same as in Example 1, and flame-retardant ceramic plates were obtained.

[0086] Comparative Example 8:

[0087] Except for adding aluminum diethylphosphinate, glass powder, phosphite antioxidant and polytetrafluoroethylene together with PBT resin through the main feed port and not side feeding in zone nine, the other raw materials, dosages and preparation conditions are the same as in Example 1, and flame-retardant ceramic plates are obtained.

[0088] Comparative Example 9:

[0089] Except for changing the amount of mica coated with silicone rubber to 750g, the amount of PBT resin to 3085g, and the amount of dimethyl silicone oil solution containing hydrogen silicone oil injected in the fourth zone to 5g, the other raw materials, amounts, and preparation conditions are the same as in Example 1, and flame-retardant ceramic sheets and their hot-pressed parts are obtained.

[0090] Comparative Example 10:

[0091] Except for changing the amount of mica coated with silicone rubber to 1900g, the amount of PBT resin to 1935g, the amount of dimethyl silicone oil solution containing hydrogen silicone oil injected in the four zones to 12.5g, and the hot pressing pressure to 3MPa, the other raw materials, amounts and preparation conditions are the same as in Example 1, and flame-retardant ceramic sheets and their hot-pressed parts are obtained.

[0092] Comparative Example 11:

[0093] Except for changing the dimethyl silicone oil solution containing hydrogen silicone oil injected in the fourth zone to 13.8g, the other raw materials, dosages and preparation conditions were the same as in Example 1, and flame-retardant ceramic plates were obtained.

[0094] Comparative Example 12:

[0095] Except for changing the hydrogen-containing silicone oil injected in zone 8 to 1.3g, the other raw materials, dosages and preparation conditions were the same as in Example 1, and flame-retardant ceramic plates were obtained.

[0096] Comparative Example 13:

[0097] Except for replacing the silicone rubber-coated mica with 1250g of silicone rubber-coated mica with a shell containing methyl MQ silicone resin obtained in Example 6, the other raw materials, amounts and preparation conditions were the same as in Example 1, and flame-retardant ceramic plates were obtained.

[0098] Comparative Example 14:

[0099] Except for the omission of polycarbonate and zinc dihydrogen phosphate, and the change of the amount of PBT resin to 2960g, the other raw materials, amounts, and preparation conditions were the same as those in Comparative Example 1, and PBT-based flame-retardant ceramic sheets were obtained.

[0100] Performance testing:

[0101] The plates were prepared according to the above examples, and the samples were placed in an environment of 23°C and 50% relative humidity for 24 hours before testing.

[0102] Melt storage modulus plateau and apparent yield stress: A 25mm diameter disc was punched from the sheet metal and measured on a rotational rheometer with 25mm parallel plates, gaps equal to the sheet thickness, and under a nitrogen atmosphere at 250℃. First, a frequency scan was performed from 0.1 rad / s to 1 rad / s at 0.5% strain. Ten logarithmically spaced frequency points were selected within this range. If the ratio of the maximum to minimum storage modulus within this range was not greater than 2, the arithmetic mean of the storage modulus at each frequency point was taken as the storage modulus plateau. If this ratio was greater than 2 and the storage modulus continuously decreased with frequency, it was recorded as "no plateau". Then, a stress ramp scan was performed, with shear stress increasing logarithmically from 1 Pa to 60000 Pa (20 ramps per decade, each ramp held for 30 seconds), while simultaneously recording the apparent viscosity at each ramp. A double logarithmic curve was plotted between apparent viscosity and shear stress, and the shear stress corresponding to the intersection of the least squares fitted lines of the low-stress and high-stress segments was taken as the apparent yield stress, rounded to 50 Pa. The shear rate under the same shear stress level was not less than 0.01 s⁻¹. -1 Continuous flow is defined as flow that continues until the end of the specified stage. A curve with no slope inflection within the range of 1–60000 Pa and continuous flow from 10 Pa onwards is recorded as “not detected”. A curve where no continuous flow occurs throughout a shear stress increase to 60000 Pa is recorded as ">60000". Three parallel measurements are performed, and the average value is taken.

[0103] 350℃ Sagging Deflection: Cut a 50mm long and 10mm wide sample from the sheet metal. The sample thickness is the same as the sheet metal thickness. Place the sample flat on two knife-edge supports with a span of 40mm, with each end overhanging 5mm. Place a base plate 12mm below the supports. Place the sample in a 350℃ hot air oven for 10 minutes. After cooling to room temperature, measure the sag deflection of the sample's midpoint relative to the two supports using a height gauge. "Dripping" refers to the sample dripping, falling between supports, or the midpoint touching the base plate. The self-weight deflection increases as the sample thickness decreases; the difference in thickness must be considered when comparing samples of different thicknesses. Perform three parallel measurements and take the average value. For hot-pressed parts, the specimen was cut from the side wall at the point of maximum tension of the specimen. The thickness of the specimen was measured with a micrometer and then determined using the same method. A 50mm long specimen was also cut from the same location, and its length before the test was measured with a digital caliper with a resolution of 0.01mm. After holding the specimen at the same temperature for 10 minutes, the length was measured again. The length shrinkage rate was calculated as a percentage of the difference between the lengths before and after the test and the length before the test. For injection-molded parts, a 50mm long section was cut from the 80mm long, 10mm wide, and 4mm thick specimen obtained under the "Mechanical Properties and Flammability" section, and the measurement method was the same.

[0104] Burn-through time using a spray gun: Cut a 100mm × 100mm sample from the plate, clamp it along the upper edge and hang it vertically. Use a butane spray gun (nozzle 50mm from the sample surface, flame contact temperature calibrated to 1000℃±50℃ by a type K thermocouple) to continuously burn the center of the sample. Record the time it takes for a light-transmitting hole to appear on the back of the sample. If no hole appears within 600s, it is recorded as "not burned through". Perform three parallel measurements and take the average value.

[0105] Three-point bending strength and linear shrinkage of the ignition residue: A sample 80 mm long and 10 mm wide was cut from the plate. After measuring the length with vernier calipers, it was placed in a corundum boat with an inner cavity of 85 mm × 11 mm × 6 mm and ignited in a muffle furnace preheated to 1000 °C for 30 min. After cooling to below 200 °C in the furnace, the sample was removed, and the length of the residue was measured. The linear shrinkage was calculated as the percentage of the difference in length before and after ignition to the length before ignition. The fracture load of the residue was measured on an electronic universal testing machine using a three-point bending method (span 50 mm, loading rate 0.5 mm / min, force sensor with a range of 5 N). The width and thickness of the residue at the mid-span were measured using a digital caliper with a resolution of 0.01 mm. The bending strength was calculated using the formula for a rectangular section beam. Another sample was placed in a muffle furnace preheated to 600 °C for 30 min, and the bending strength of the residue ignited at 600 °C was measured using the same method. Three parallel measurements were performed, and the average value was taken.

[0106] Mechanical properties and combustion properties: After the sheet material is cut into pellets and dried at 120℃ for 4 hours, it is injection molded into specimens according to GB / T 17037.1-2019 "Preparation of injection molded specimens for thermoplastic materials - Part 1: General principles and preparation of multipurpose specimens and strip specimens". Notched impact strength was determined according to GB / T 1843-2008 "Determination of impact strength of plastic cantilever beam", with a specimen size of 80mm×10mm×4mm, type A notch, and the average value of 5 specimens was taken; tensile strength was determined according to GB / T 1040.2-2022 "Determination of tensile properties of plastics - Part 2: Test conditions for molding and extruded plastics", type 1A specimen, test speed 50mm / min, and the average value of 5 specimens was taken; limiting oxygen index was determined according to GB / T 2406.2-2009 "Determination of burning behavior of plastics by oxygen index method - Part 2: Room temperature test", with a specimen size of 80mm×10mm×4mm, and the average value of 3 parallel tests was taken; vertical flammability rating was determined according to GB / T 2408-2021 "Determination of flammability of plastics - Horizontal and vertical methods", with a specimen size of 125mm×13mm×1.6mm. The sheet material of Comparative Example 5 could not be melt-molded after being granulated. Its mechanical properties and flammability test specimens were prepared by machining the sheet material: the vertical burning test specimens were machined to 125mm×13mm×1.6mm, the notched impact and limiting oxygen index test specimens were machined to 80mm×10mm×2.5mm, and the tensile test specimens were machined according to Type 1B of GB / T 1040.2-2022 with a thickness of 2.5mm, which is the same as the sheet material thickness. The thickness of the test specimens for notched impact strength, tensile strength and limiting oxygen index is different from the 4mm injection molded test specimens of the other examples. The influence of the test specimen thickness should be taken into account when making comparisons.

[0107] Hot pressing formability: The sheet metal was heated according to the blank size, preheating and transfer method of each example, and then placed in the mold. The forming pressure was increased from 0.5 MPa to 3 MPa in increments of 0.5 MPa. The minimum forming pressure was the lowest pressure at which the part filled the cavity, had no missing material at the edges and corners, and did not crack after demolding. The state of the part was recorded. If a complete part could not be obtained even when the pressure was increased to 3 MPa, the minimum forming pressure was recorded as "—". After demolding and cooling to room temperature, the part was placed back in the mold cavity. The maximum gap between the part and the mold surface was measured with a feeler gauge as the mold deviation. The reading was taken as the thickness of the feeler gauge blade, and the average value of 3 parts was taken. The nominal strain at the point of maximum tension of the formed part was calculated according to the aforementioned definition from the thickness of the sheet metal before forming and the thickness of the formed part at that point. The sheet metal of Comparative Example 1 and Comparative Example 2 was preheated according to the conditions of Example 1. When the sheet metal was transferred into the mold, it flowed and cracked. This was recorded as "flowed and cracked when transferred into the mold after preheating, unable to be formed". Comparative Examples 3, 4, 6, 7, 8, 11, 12, 13 and 14 only measured the properties of the boards.

[0108] The results are shown in Tables 1 to 4. In the tables, "No plateau" indicates that the storage modulus continuously decreases with frequency, "Not detected" indicates that the melt flows continuously when the shear stress rises above 10 Pa, ">60000" indicates that the melt does not flow even when the shear stress rises to 60000 Pa, "Dripping" indicates that the sample drips, falls from between the supports, or touches the base plate at the midpoint during the sag test, "Not burned through" indicates that no holes appear after 600 s of burning with the spray gun, and "—" indicates that it cannot be measured due to failure to form, cracking of the part, or dripping of the sample.

[0109] The test results of injection molded samples not listed in Tables 1 to 4 are as follows: The 4mm thick sample obtained by injection molding from the sheet of Example 1 at 350℃ has a melt sag deflection of 9.4mm. The injection molded samples of Comparative Example 1 and Comparative Example 2 dripped in the same test. The sheet of Comparative Example 5 could not be injection molded after being cut into pellets.

[0110] Table 1. Melt storage modulus plateau, apparent yield stress, melt sag deflection, and burn-through time of the plates obtained in each embodiment and comparative example.

[0111]

[0112] Table 2. Flexural strength and linear shrinkage of the ignition residues of the plates obtained in each embodiment and comparative example.

[0113] Example 1 0.9 2.5 7.1 Example 2 0.9 1.9 7.9 Example 3 1.1 2.8 6.5 Example 4 1.3 3.0 5.6 Example 5 1.6 3.2 5.4 Comparative Example 1 0.3 0.7 9.5 Comparative Example 2 0.2 0.7 9.1 Comparative Example 3 0.5 1.1 8.6 Comparative Example 4 0.7 1.6 8.0 Comparative Example 5 0.4 0.9 8.9 Comparative Example 6 0.7 1.5 7.8 Comparative Example 7 0.6 1.7 8.0 Comparative Example 8 0.4 1.0 8.9 Comparative Example 9 0.5 1.4 8.2 Comparative Example 10 1.3 3.0 6.1 Comparative Example 11 0.7 1.3 8.1 Comparative Example 12 0.7 1.8 7.7 Comparative Example 13 0.9 2.5 6.7 Comparative Example 14 0.2 0.5 9.9

[0114] Table 3 Mechanical and flammability properties of materials obtained in each embodiment and comparative example

[0115]

[0116] Table 4. Hot pressing formability of various sheet materials and weld line deflection of molded parts

[0117]

[0118] Results analysis:

[0119] As shown in Tables 1 to 4, the plates from Examples 1 to 5 all exhibited a storage modulus plateau (53000–257900 Pa) and apparent yield stress at 250°C, with a melt sag deflection not exceeding 3.6 mm at 350°C. They did not burn through after 600 seconds of torch burning and could be hot-pressed into complete parts under a pressure not exceeding 1.5 MPa. Compared to Comparative Example 1, the flexural strength of the residue after burning at 600°C in Example 1 increased from 0.3 MPa to 0.9 MPa, the flexural strength of the residue after burning at 1000°C increased from 0.7 MPa to 2.5 MPa, the linear shrinkage rate of the residue decreased from 9.5% to 7.1%, and the notched impact strength was 6.0 kJ / m². 2The residue strength was not lower than that of Comparative Example 1; Comparative Example 14, which did not contain polycarbonate, also dripped in the sag test, and the flexural strength of the residue at 600℃ and 1000℃ was 0.2MPa and 0.5MPa, respectively, and the notched impact strength was 4.3kJ / m. 2 This indicates that the silicone rubber shell of the silicone rubber-coated mica forms a network by bridging each other in the PBT melt. Under the condition of a relatively equal total amount of inorganic components, it improves the integrity of the ceramic layer and the strength of the residue from the mid-temperature zone after PBT decomposition, and enables the sheet to maintain its shape before ceramicization, while maintaining its hot-pressing formability.

[0120] Comparative Example 2 had the same composition as Example 1, but the silicone rubber was introduced as free raw rubber along with PBT and vulcanized into dispersed particles in a single step in the mixing section. Its sheet exhibited no storage modulus plateau at 250°C, no detectable yield stress, dripped during the sag test at 350°C, burned through after 109 seconds of spray gun burning, and fractured upon being transferred to the mold after preheating. The injection-molded sample also dripped during the sag test. The residual flexural strength at 1000°C was 0.7 MPa; its notched impact strength was 6.3 kJ / m. 2 This is equivalent to Example 1 (Tables 1 to 3). It shows that when the same amount of silicone rubber is dispersed as isolated particles, the particles and mica flow with the melt after PBT melts, and the material cannot maintain its plate shape. By pre-coating the surface of zinc borate-deposited mica with silicone rubber as a shell, and then triggering bridging between the shells after dispersion, the plate can maintain its shape before ceramicization, and the residual strength is also improved.

[0121] As shown in Table 1, in Comparative Example 3 without the injection of the second-stage triggering agent, the shells of the silicone rubber-coated mica did not bridge each other after gelation in the four zones. The storage modulus plateau of the plate at 250℃ was only 2000 Pa, the apparent yield stress was 150 Pa, and the dripping and burn-through time in the sag test was 136 s. It is evident that after the shells gel and disperse, a second-stage triggering agent is needed in the transport section to bridge the shells at the contact points so that the silicone rubber-coated mica can form a load-bearing network.

[0122] When the second stage of hydrogen-containing silicone oil is incorporated into zone four and injected simultaneously with the first stage (Comparative Example 4), bridging occurs during shearing in the mixing section and is subsequently destroyed by shearing. Table 1 shows that the storage modulus plateau of this plate is only 9800 Pa, the apparent yield stress is 850 Pa, and the dripping and burn-through time in the sag test is 260 s. Bridging occurs in the low-shear transport section and is fixed by calendering, allowing the network to remain continuous. This is the reason why the second stage trigger agent is injected in zone eight.

[0123] As shown in Table 1, the energy storage modulus plateau of Comparative Example 11 is 7000 Pa, the apparent yield stress is 350 Pa, and the dripping and burn-through time in the sag test is 172 s. In this example, the amount of hydrogen-containing silicone oil in the first stage is increased to an equivalent molar amount to vinyl groups. When the shell gels in zone four, the vinyl groups are almost exhausted, and the hydrogen-containing silicone oil injected in zone eight does not have enough bridging sites. This indicates that the amount of hydrogen-containing silicone oil in the first stage must be insufficient to retain residual vinyl groups in the shell, so that bridging can occur in the second stage.

[0124] In Comparative Example 12, the amount of hydrogen-containing silicone oil in the second stage was reduced to 1.3g, resulting in insufficient bridging points. The apparent yield stress of the plate was 1850Pa, the sag deflection was 10.1mm, and the burn-through time was 285s, which did not reach 600s (Table 1). When the amount of the second stage trigger agent was too low, the network was incomplete. The amount used in Example 2 was sufficient to maintain the shape of the plate and prevent burn-through within 600s.

[0125] The untreated silicone rubber-coated mica (Comparative Example 7) lacks covalent anchoring between its shell and the mica; the apparent yield stress of this sheet, as shown in Tables 1 to 3, is 2400 Pa, the sag deflection is 6.8 mm, the residual flexural strength at 600℃ and 1000℃ is 0.6 MPa and 1.7 MPa, respectively, the linear shrinkage rate is 8.0%, the burn-through time is 400 s, and the notched impact strength decreases to 5.1 kJ / m. 2 The tensile strength decreased to 38.6 MPa. It can be seen that silane anchoring prevents the gel shell from peeling off from the mica during shearing. After being exposed to fire, the silica transformed from the shell remains bonded to the mica surface, thus improving network strength, residual strength, and interfacial bonding.

[0126] In Comparative Example 6, without depositing zinc borate on the mica but adding an equal amount of zinc borate to the PBT phase, the apparent yield stress and weld deflection of the sheet were comparable to those of Example 1 (see Table 1). It also did not burn through during torch burning. However, the flexural strength of the residue at 600℃ and 1000℃ in Table 2 were 0.7 MPa and 1.5 MPa, respectively, with a linear shrinkage rate of 7.8%. When zinc borate is deposited on the mica surface and covered by a shell, the precursor of the binder phase is already located at the skeleton contact point without migration. The dehydration products and the silica and glass powder transformed from the shell form a binder phase at this point, improving the strength of the residue.

[0127] When aluminum diethylphosphinate, glass powder, phosphite antioxidant, and polytetrafluoroethylene were added together with PBT resin through the main feed port (Comparative Example 8), the sheet exhibited no storage modulus plateau, no detectable yield stress, dripped during the sag test, and had a burn-through time of 122 s (Table 1). This indicates that if the phosphorus-containing flame retardant and phosphite antioxidant enter the melt before triggering, it will deactivate the platinum in the shell, preventing the shell from gelling and bridging. These components must be added after the second stage of triggering agent injection.

[0128] When the amount of mica used in silicone rubber overlay was 15% (Comparative Example 9), the volume fraction of mica was insufficient to form a continuous network, causing dripping during the sheet sag test and dripping in the hot-pressed sample, with a burn-through time of 211 s. When the amount was 38% (Comparative Example 10), the residual flexural strength at 1000℃ was 3.0 MPa, the sag deflection was 0.4 mm, but the notched impact strength decreased to 3.7 kJ / m. 2 The tensile strength dropped to 32.8 MPa, and the part cracked at the point of maximum tension when the pressure was increased to 3 MPa. The amount of mica used in the silicone rubber overlay of Examples 2, 1 and 3 was 21%, 25% and 32% respectively, and all of them could maintain shape and be molded, and the notched impact strength was not lower than that of Comparative Example 1 (see Tables 1, 3 and 4).

[0129] Comparative Example 5, with the same composition as Comparative Example 2, was modified by adding triallyl isocyanurate and then irradiated with an electron beam. After matrix crosslinking, the platen exhibited a storage modulus plateau of 203900 Pa at 250°C, a melt sag deflection of 1.3 mm, and did not burn through during torch burning. It could be hot-pressed into a complete part at 1.5 MPa, but the mold deviation was 1.1 mm. The molded part sample showed a length shrinkage rate of 14.3% at 350°C, and a notched impact strength of 4.0 kJ / m. 2 The flexural strength of the residue at 1000℃ was 0.9 MPa, and it could not be injection molded after pelletizing (Tables 1 to 4). Example 1 achieved considerable shape retention without irradiation, with a mold deviation of 0.3 mm and a length shrinkage rate of 3.3% for the molded sample, while maintaining notched impact strength and reprocessability. The flexural strength of the residue was also higher than that of Comparative Example 5.

[0130] Example 4 uses a 1:1 mass ratio solution of hydrogen-containing MQ silicone resin and hydrogen-containing silicone oil as the second-stage trigger. Its composition and process conditions are the same as in Example 1. The amount of the second stage catalyst, calculated based on Si-H, is comparable to that in Example 1 (1.08 mol and 1.10 mol per 100 kg of compound). The storage modulus plateau and apparent yield stress (109400 Pa and 6750 Pa) of the board are comparable to those in Example 1. The residual flexural strength at 600℃ increases from 0.9 MPa to 1.3 MPa, the residual flexural strength at 1000℃ increases from 2.5 MPa to 3.0 MPa, the linear shrinkage decreases from 7.1% to 5.6%, and the notched impact strength is 5.9 kJ / m². 2 (Tables 1 to 3). Example 5 also exhibits the same changes compared to Example 3, with the flexural strength of the residue at 1000°C increasing from 2.8 MPa to 3.2 MPa, and the linear shrinkage decreasing from 6.5% to 5.4%. This indicates that when a hydrogen-containing silicone resin with Q units is used as the second-stage trigger, the Q units are enriched at the bridging nodes, and the nodes remain connected during the conversion of siloxane to silica, thus reducing the shrinkage of the residue and increasing its strength.

[0131] In Comparative Example 13, the same amount of methyl MQ silicone resin as in Example 4 was incorporated into the shell during encapsulation. The second-stage trigger was still hydrogen-containing silicone oil. Its residual flexural strength at 600°C and 1000°C was 0.9 MPa and 2.5 MPa, respectively, and its linear shrinkage rate was 6.7%, comparable to Example 1 (Table 2). It can be seen that the above changes stem from the overall approach of using hydrogen-containing MQ silicone resin as the second-stage trigger, allowing the Q-units to enter with the trigger and form bridging nodes at the shell contact points. When methyl MQ silicone resin without Si-H and not involved in bridging is dispersed inside the shell, its mass fraction in the shell is less than 1%, and this change is not produced.

[0132] In Example 1, the specimen thickness at the point of maximum tensile stress in the hot-pressed part was 1.98 mm, with a nominal strain of 26%. Its 350°C melt sag deflection was 8.4 mm, and the length shrinkage rate was 3.3%. The deflection was higher than the sheet metal's 2.7 mm, yet the specimen maintained its shape (Table 4). The self-weight deflection was inversely proportional to the square of the specimen thickness. Reducing the specimen thickness from 2.5 mm to 1.98 mm increased the deflection by approximately 1.6 times; the remaining increase came from the effect of molding tension on the network. The specimen obtained by injection molding from sheet metal pellets had a thickness of 4 mm, greater than the sheet metal's 2.5 mm. Under the same network modulus, its deflection should have been lower than the sheet metal, but the measured value was 9.4 mm. The injection-molded specimen in Comparative Example 2 dripped. This indicates that the bridging network was largely preserved during the tensile deformation of hot-pressing. Injection molding shear caused the network to break into clusters, reducing its shape retention but still exceeding that of silicone rubber, a material where dispersed particles exist.

[0133] The limiting oxygen index of each embodiment ranged from 30.6% to 33.3%, and all achieved V-0 rating in vertical burning. The tensile strength remained above 85% of that of Comparative Example 1, with the lowest being 40.7 MPa in Example 3 (Table 3). Examples 3 and 5 had a higher amount of mica used in the silicone rubber coating and a lower amount of aluminum diethylphosphinate, resulting in a lower limiting oxygen index than other embodiments, but a higher residual flexural strength. This trade-off can be made according to the requirements of flame retardancy and ceramic strength for the structural components.

[0134] Those skilled in the art should understand that the discussion of any of the above embodiments is merely exemplary and is not intended to imply that the scope of the invention is limited to these examples; within the framework of the invention, the technical features of the above embodiments or different embodiments can also be combined, and there are many other variations of the different aspects of the invention as described above, which are not provided in detail for the sake of brevity.

Claims

1. A method for preparing a flame-retardant ceramic polymer alloy material for structural components of new energy battery packs, characterized in that, Includes the following steps: (1) Disperse wet sericite powder in water, add boric acid and zinc oxide, and deposit zinc borate on the surface of mica under heating and stirring. Filter, wash and dry to obtain zinc borate deposited mica; treat zinc borate deposited mica with the hydrolysate of vinyltriethoxysilane, and then knead it with methyl vinyl silicone rubber raw rubber, platinum catalyst and hydrosilylation inhibitor to coat the surface of mica with raw rubber. Chop it to obtain platinum-containing and non-crosslinked silicone rubber coated mica. (2) The dried polybutylene terephthalate and toughening agent are added and melted through the main feed port of the twin-screw extruder; the silicone rubber-coated mica obtained in step (1) is added to the melt through the side feed port after the melting section, and at the same time, the first section of hydrogen-containing silicone oil is injected into the barrel section where the side feed port is located, so that the silicone rubber shell gels and disperses in the subsequent melt mixing section; the ratio of the amount of Si-H in the first section of hydrogen-containing silicone oil to the vinyl equivalent is 0.4 to 0.8, and the vinyl equivalent is calculated according to the silicone rubber-coated mica added in step (2); (3) A second triggering agent is injected into the conveying section after the melting and mixing section to bridge the contact points of the silicone rubber shells. The second triggering agent is hydrogen-containing silicone oil or a solution of hydrogen-containing MQ silicone resin and hydrogen-containing silicone oil. The dosage of the second triggering agent based on Si-H is 0.8 to 1.5 mol per 100 kg of mixed material. After the injection of the second triggering agent, aluminum diethylphosphinate, low softening point borosilicate glass powder, phosphite antioxidant and polytetrafluoroethylene are added through the side feed port. (4) The melt is extruded through a T-die and calendered into a sheet to obtain the flame-retardant ceramic polymer alloy material; The silicone rubber-coated mica accounts for 20% to 33% of the total mass of the compound, and the total mass of the compound is the sum of the masses of all components added in steps (2) and (3); the mass ratio of methyl vinyl silicone rubber raw rubber to mica in the silicone rubber-coated mica is 0.5 to 1.

2.

2. The preparation method according to claim 1, characterized in that, In step (1), the amount of zinc oxide and boric acid used is 12% to 25% of the mica mass based on the production of 2ZnO·3B2O3·3.5H2O, and the amount of vinyltriethoxysilane used is 0.8% to 2% of the mica mass.

3. The preparation method according to claim 1, characterized in that, In step (1), zinc borate is deposited at 88–96 °C for 4–6 h; the platinum catalyst is 5–20 ppm of the mass of the methyl vinyl silicone rubber raw material, the hydrosilylation inhibitor is 0.05%–0.2% of the mass of the methyl vinyl silicone rubber raw material, and the kneading is carried out at 60–80 °C for 30–60 min.

4. The preparation method according to claim 1, characterized in that, Based on the total mass of the compound, polybutylene terephthalate (PET) accounts for 45%–56%, toughening agent accounts for 2%–4%, aluminum diethylphosphinate accounts for 8%–13%, low softening point borosilicate glass powder accounts for 4%–10%, phosphite antioxidant accounts for 0.1%–0.3%, and polytetrafluoroethylene accounts for 0.2%–0.5%. The toughening agent is an ethylene-methyl acrylate-glycidyl methacrylate copolymer.

5. The preparation method according to claim 1, characterized in that, In step (2), the temperature of the silicone rubber-coated mica and the first section of hydrogen-containing silicone oil addition and the melting and mixing section is 245-255℃, and the screw speed is 250-350r / min; in step (3), the temperature of the conveying section is 245-255℃, and the residence time of the material from the second section trigger injection point to the die head is 40-80s.

6. The preparation method according to claim 1, characterized in that, In step (3), the second trigger is a solution of hydrogen-containing MQ silicone resin and hydrogen-containing silicone oil, with the hydrogen-containing MQ silicone resin accounting for 45% to 70% of the mass of the solution.

7. The preparation method according to claim 1, characterized in that, In step (4), the thickness of the calendered board is 2-3 mm, and the temperature of the calendering roller is 60-100℃.

8. The preparation method according to any one of claims 1 to 7, characterized in that, It also includes step (5): heating the plate obtained in step (4) to 235-245°C, placing it in a mold with a mold temperature of 80-120°C, and hot-pressing it with 1-3 MPa to form a battery pack structural component, wherein the nominal strain at the maximum stretch of the formed component does not exceed 30%.

9. A flame-retardant ceramic polymer alloy material for structural components of new energy battery packs, characterized in that, It is prepared by any one of claims 1 to 8.

10. The application of the flame-retardant ceramic polymer alloy material as described in claim 9 in the preparation of the top cover or module end plate of a new energy battery pack.

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