Flame-retardant polyester material and preparation method thereof

Abstract

The invention discloses a flame-retardant polyester material and a preparation method thereof, and belongs to the technical field of polyester materials. The flame-retardant polyester material is prepared from the following raw material components in parts by mass: intrinsic flame-retardant polyester resin, ionic liquid functionalized boron nitride nanosheets, ammonium polyphosphate, an antioxidant, a lubricant, calcium carbonate and a toughening agent, the intrinsic flame-retardant polyester resin is obtained by modifying aluminum hydroxide with 1-hydroxyethylidene-1, 1-diphosphonic acid and then carrying out esterification and polycondensation on the modified aluminum hydroxide, terephthalic acid monomers and ethylene glycol; the terephthalic acid monomer at least comprises 2-acetyl terephthalic acid; the ionic liquid functionalized boron nitride nanosheet is prepared by compounding an ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate and hexagonal boron nitride, wherein the ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate and the hexagonal boron nitride are compounded; the toughening agent is obtained by copolymerizing glycidyl acrylate, glycidyl acrylate and 4-vinyl benzaldehyde.

Description

Technical Field

[0001] The present invention relates to a flame - retardant polyester material and a preparation method thereof. Background Art

[0002] Polyethylene terephthalate (PET) is a common polyester material, which is widely used in many fields such as textiles, construction, transportation, and medical and health due to its excellent wear resistance, heat resistance, chemical stability, and high mechanical strength. However, as a linear thermoplastic polymer material, the limiting oxygen index (LOI) of PET is only about 21%, indicating that it is extremely flammable in air, and it is easy to cause continuous combustion and even spread after encountering fire, posing a great fire safety hazard.

[0003] With the continuous improvement of the society's requirements for material safety, improving the flame - retardant performance of polyester materials such as PET has become one of the current research focuses. In addition, in practical applications, polyester materials often face problems of external force impact or mechanical damage. Therefore, while improving their flame retardancy, how to maintain or enhance their impact resistance is also particularly important. Traditional flame - retardant modification methods are mainly achieved by adding or reactive flame retardants, but they often have problems such as low flame - retardant efficiency, poor compatibility with the matrix, and affecting the mechanical properties of the material.

[0004] In summary, developing a new modification method that can significantly improve the flame - retardant performance of polyester materials without damaging their mechanical properties, especially impact resistance, has important practical significance and broad application prospects. Summary of the Invention

[0005] The purpose of the present invention is to provide a flame - retardant polyester material and a preparation method thereof to solve the technical problems mentioned in the above background art.

[0006] The technical solution to achieve the purpose of the present invention is as follows: In the first aspect, the present invention provides a flame - retardant polyester material. Calculated by mass fraction, the raw material components include 97 - 99 parts by mass of intrinsically flame - retardant polyester resin, 1 - 3 parts by mass of ionic - liquid - functionalized boron nitride nanosheets, 0.9 - 1.1 parts by mass of ammonium polyphosphate, 0.4 - 1 part by mass of antioxidant, 0.3 - 0.5 part by mass of lubricant, 65 - 67 parts by mass of calcium carbonate, and 5 - 7 parts by mass of toughening agent.

[0007] The present invention significantly improves the flame retardancy and impact toughness of the flame - retardant polyester material by using an intrinsically flame - retardant polyester resin and introducing ionic - liquid - functionalized boron nitride nanosheets, ammonium polyphosphate, and toughening agent.

[0008] Further, the intrinsically flame-retardant polyester resin is obtained by modifying aluminum hydroxide with 1-hydroxyethylidene-1,1-diphosphonic acid and then performing esterification and polycondensation with terephthalic acid monomer and ethylene glycol.

[0009] The intrinsically flame-retardant polyester resin of the present invention is obtained by modifying aluminum hydroxide with 1-hydroxyethylidene-1,1-diphosphonic acid and then performing esterification and polycondensation with terephthalic acid monomer and ethylene glycol; wherein, the introduction of aluminum hydroxide and organic phosphoric acid can promote the formation of a dense carbon layer, and the dense carbon layer is an excellent barrier for heat insulation and oxygen isolation, insulating heat and isolating oxygen. At the same time, the decomposition of aluminum hydroxide can release water vapor to dilute combustible gases, thereby effectively improving the flame-retardant performance of the polyester resin.

[0010] Further, the terephthalic acid monomer at least includes 2-acetyl terephthalic acid.

[0011] Further, the ionic liquid-functionalized boron nitride nanosheets are obtained by compounding ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate with hexagonal boron nitride.

[0012] The present invention adds ionic liquid-functionalized boron nitride nanosheets obtained by compounding ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate with hexagonal boron nitride; wherein, ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate ionic liquid (IL) is a new type of green solvent with high thermal stability and good solubility, and shows excellent flame-retardant performance. By compounding ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate with hexagonal boron nitride, hexagonal boron nitride can be delaminated to obtain boron nitride nanosheets. After the ionic liquid-functionalized boron nitride nanosheets of the present invention are mixed with ammonium polyphosphate, the physical barrier effect of the boron nitride nanosheets, the catalytic charring effect of ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate, and the combined effect of ammonium polyphosphate releasing non-combustible gases and dehydrating to form carbon can synergistically flame-retard and further enhance the flame-retardant performance of the polyester resin.

[0013] Further, the toughening agent is obtained by copolymerizing glycidyl acrylate, glycidyl acrylate, and 4-vinylbenzaldehyde.

[0014] The present invention adds a toughening agent obtained by copolymerizing glycidyl acrylate, glycidyl acrylate, and 4-vinylbenzaldehyde. The epoxy group on the glycidyl acrylate structural unit in the toughening agent can react with the end groups of the polyester polymer macromolecular chains to form a "bridge", connecting the macromolecular chains, thereby increasing the molecular weight and viscosity, playing a good chain extension role and enhancing and toughening the polyester at the same time.

[0015] In a second aspect, the present invention provides a preparation method of a flame-retardant polyester material as described in the first aspect, including the following preparation steps: (1)Weigh and proportion each raw material component according to the corresponding mass parts. (2)First, put the intrinsically flame-retardant polyester resin, ionic liquid-functionalized boron nitride nanosheets, and toughening agent weighed in step (1) into a torque rheometer, and carry out intensive mixing and blending at 260-265 °C and 50-70 r / min for 3-9 min. Subsequently, mix with ammonium polyphosphate, antioxidant, lubricant, and calcium carbonate in a high-speed mixer at room temperature at high speed for 10-15 min, then add them to a twin-screw extruder for full melting and plasticization, kneading and mixing, extruding through the die head, drawing, cooling, pelletizing, drying, and finally packaging.

[0016] When preparing the flame-retardant polyester material of the present invention, first carry out intensive mixing of the intrinsically flame-retardant polyester resin, ionic liquid-functionalized boron nitride nanosheets, and toughening agent. Under the catalytic action of the ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate in the ionic liquid-functionalized boron nitride nanosheets, the acetylbenzene on the intrinsically flame-retardant polyester resin reacts with benzaldehyde on the toughening agent to undergo a Claisen-Schmidt reaction to form a chalcone derivative. The benzene ring in the chalcone derivative forms a large π-conjugated system with α,β-unsaturated carbonyl, which can efficiently absorb ultraviolet light (especially in the UVB band), convert light energy into heat energy or fluorescence and release it, reduce the penetration of ultraviolet rays, and thus endow the flame-retardant polyester material with good anti-ultraviolet aging performance.

[0017] Furthermore, the preparation method of the intrinsically flame-retardant polyester resin is as follows: Add 415-417 mass parts of 2-acetylterephthalic acid, 23.2-23.3 mass parts of 1-hydroxyethylidene-1,1-diphosphonic acid-modified aluminum hydroxide, 161.3-161.4 mass parts of ethylene glycol, and 0.098-0.100 mass parts of antimony trioxide into a magnetic stirring reactor, and carry out an esterification reaction under nitrogen protection at 0.25-0.35 MPa and 234-236 °C. When the esterification temperature drops to 100 °C, the esterification reaction is completed. After discharging the pressure to atmospheric pressure and the water generated by esterification, react at atmospheric pressure for 28-32 min; then enter the pre-polycondensation stage, with a vacuum degree of 0.05 MPa, the temperature rises from 234-236 °C to 274-276 °C, and the time is 28-32 min; the final polycondensation is carried out under full vacuum and at a temperature of 274-276 °C. When the stirring power is 16 kW, the reaction ends, and nitrogen is introduced to discharge the material to obtain the intrinsically flame-retardant polyester resin.

[0018] Further, the preparation steps of the 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide are as follows: Mix 300 parts by mass of deionized water and 10 - 11 parts by mass of 1-hydroxyethylidene-1,1-diphosphonic acid and stir until the 1-hydroxyethylidene-1,1-diphosphonic acid is dissolved. Then slowly add 7.6 - 8.0 parts by mass of aluminum hydroxide with a particle size of 0.1 - 25 μm. Subsequently, heat to 100 °C, react for 9.5 - 10.5 h, then perform vacuum distillation and vacuum drying to obtain the 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide; The reaction route of the 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide is as follows: 。

[0019] Further, the preparation steps of the ionic liquid-functionalized boron nitride nanosheets are as follows: Put hexagonal boron nitride into a ceramic crucible, heat it in a muffle furnace to 995 - 1005 °C and keep it for 3.5 - 4.5 h, and then naturally cool it to room temperature to obtain oxidized hexagonal boron nitride; Add 8 parts by mass of oxidized hexagonal boron nitride to a mixture of 170 parts by mass of deionized water and 35 - 37 parts by mass of the ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate, perform ultrasonic treatment for 7 - 9 h, centrifuge at 7000 - 9000 rpm for 9 - 11 min, take the precipitate, and perform vacuum drying at 55 - 65 °C to obtain the ionic liquid-functionalized boron nitride nanosheets.

[0020] Further, the preparation steps of the toughening agent are as follows: Under nitrogen protection, mix 11 - 13 parts by mass of glycidyl acrylate, 14 - 16 parts by mass of methacrylate, 2 - 4 parts by mass of 4-vinylbenzaldehyde, 29 - 30 parts by mass of dioxane, 0.2 - 0.3 parts by mass of isobutanol, and 0.25 - 0.35 parts by mass of benzoyl peroxide, stir evenly, react at 88 - 92 °C for 6.5 - 7.5 h, and then cool to room temperature; Drop the obtained copolymer solution into 300 parts by mass of methanol, and powdery precipitation will occur. Let it stand and filter; Vacuum dry the obtained precipitate at 78 - 82 °C for 3.5 - 4.5 h, and pulverize it to obtain the toughening agent.

[0021] Adopting the above technical solutions, the present invention has the following beneficial effects: (1) By using an intrinsically flame-retardant polyester resin in the flame-retardant polyester material and introducing ionic liquid-functionalized boron nitride nanosheets, ammonium polyphosphate, and a toughening agent, the present invention significantly improves the flame retardancy and impact toughness of the flame-retardant polyester material.

[0022] (2) The intrinsically flame-retardant polyester resin of the present invention is obtained by modifying aluminum hydroxide with 1-hydroxyethylidene-1,1-diphosphonic acid and then performing esterification and polycondensation with terephthalic acid monomer and ethylene glycol; wherein, the introduction of aluminum hydroxide and organic phosphoric acid can promote the formation of a dense carbon layer, and the dense carbon layer is an excellent barrier for heat insulation and oxygen isolation, insulating heat and isolating oxygen. At the same time, the decomposition of aluminum hydroxide can release water vapor to dilute combustible gases, thereby effectively improving the flame-retardant performance of the polyester resin.

[0023] (3) The present invention adds ionic liquid-functionalized boron nitride nanosheets obtained by compounding ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate with hexagonal boron nitride; wherein, ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate (IL) is a new type of green solvent with high thermal stability and good solubility, and shows excellent flame-retardant performance. By compounding ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate with hexagonal boron nitride, hexagonal boron nitride can be delaminated to obtain boron nitride nanosheets. After the ionic liquid-functionalized boron nitride nanosheets of the present invention are mixed with ammonium polyphosphate, the physical barrier effect of boron nitride nanosheets, the catalytic carbonization effect of ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate, and the combined effect of ammonium polyphosphate releasing non-combustible gases and dehydrating and carbonizing can synergistically retard the flame, further enhancing the flame-retardant performance of the polyester resin.

[0024] (4) The present invention adds a toughening agent obtained by copolymerizing glycidyl acrylate, glycidyl acrylate, and 4-vinylbenzaldehyde. The epoxy group on the glycidyl acrylate structural unit in the toughening agent can react with the end groups of the polymer macromolecular chains of the polyester to form a "bridge", connecting the macromolecular chains, thereby increasing the molecular weight and viscosity, playing a good chain extension role while enhancing and toughening the polyester.

[0025] (5) When preparing the flame-retardant polyester material of the present invention, the intrinsically flame-retardant polyester resin, ionic liquid-functionalized boron nitride nanosheets, and toughening agent are first kneaded. Under the catalytic action of ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate in the ionic liquid-functionalized boron nitride nanosheets, the acetylbenzene on the intrinsically flame-retardant polyester resin reacts with the benzaldehyde on the toughening agent to form a chalcone derivative. The benzene ring in the chalcone derivative and the α,β-unsaturated carbonyl form a large π-conjugated system, which can efficiently absorb ultraviolet light (especially in the UVB band), convert light energy into heat energy or fluorescence and release it, reduce the penetration of ultraviolet rays, and thereby endow the flame-retardant polyester material with good anti-ultraviolet aging performance. Detailed Embodiments

[0026] In order to better understand the above technical solutions, the following will describe the above technical solutions in detail in combination with specific embodiments.

[0027] The following embodiments are only used to more clearly illustrate the technical solutions of the present invention and should not be used to limit the protection scope of the present invention.

[0028] PET: PET resin, Yizheng Chemical Fiber FG600; Hexagonal boron nitride (h-BN, 99.9%, particle size 1 - 2μm), Shanghai Aladdin Biochemical Technology Co., Ltd., China; Antioxidant: Antioxidant 1010; Calcium carbonate: Zhejiang Qintang Calcium Industry Co., Ltd., QT - 8812 / 1250 mesh; Ammonium polyphosphate (APP, n≥1000), Shanghai Aladdin Biochemical Technology Co., Ltd., China; Lubricant: Calcium stearate; Glycidyl acrylate: Glycidyl methacrylate; Methacrylate: n-Butyl methacrylate; Ethylene-acrylate-glycidyl methacrylate terpolymer, grade PTW (DuPont).

[0029] (Example 1) A preparation method of a flame-retardant polyester material, comprising the following preparation steps: (1) Weigh and mix the raw material components according to the following mass fractions: 97 parts by mass of intrinsically flame-retardant polyester resin, 3 parts by mass of ionic liquid-functionalized boron nitride nanosheets, 0.9 parts by mass of ammonium polyphosphate, 0.4 parts by mass of antioxidant, 0.3 parts by mass of lubricant, 65 parts by mass of calcium carbonate, and 5 parts by mass of toughening agent; (2) First, put the intrinsically flame-retardant polyester resin, ionic liquid-functionalized boron nitride nanosheets, and toughening agent weighed in step (1) into a torque rheometer, and carry out internal mixing and blending at 260°C and 50 r / min for 3 min. Then, mix with ammonium polyphosphate, antioxidant, lubricant, and calcium carbonate at room temperature and high speed in a high-speed mixer for 10 min, and then add them into a twin-screw extruder. The temperatures of each section of the screw of the twin-screw extruder from the feeding port to the head are 230°C, 240°C, 240°C, 250°C, 260°C, 250°C, 240°C, 230°C, 230°C respectively, and the screw speed is 400 rpm. Under the conveying and shearing actions of the twin-screw extruder, it is fully melted, plasticized, kneaded and blended, extruded through the head, drawn into strips, cooled, pelletized, dried, and finally packaged.

[0030] The preparation method of the intrinsically flame-retardant polyester resin is as follows: Add 415 parts by mass of 2-acetyl terephthalic acid, 23.2 parts by mass of 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide, 161.3 parts by mass of ethylene glycol, and 0.098 parts by mass of antimony trioxide into a magnetic stirring reactor. Carry out an esterification reaction under nitrogen protection at 0.25 MPa and 234 °C. When the esterification temperature drops to 100 °C, the esterification reaction is completed. After discharging the pressure to atmospheric pressure and the water generated by esterification, react for 28 min under atmospheric pressure; then enter the pre-polycondensation stage, with a vacuum degree of 0.05 MPa, the temperature rises from 234 °C to 274 °C, and the time is 28 min; the final polycondensation is carried out under full vacuum and at a temperature of 274 °C. When the stirring power is 16 kW, the reaction ends, and nitrogen is introduced to discharge the material to obtain the intrinsically flame-retardant polyester resin.

[0031] The preparation steps of the 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide are as follows: Mix 300 parts by mass of deionized water and 10 parts by mass of 1-hydroxyethylidene-1,1-diphosphonic acid and stir until the 1-hydroxyethylidene-1,1-diphosphonic acid is dissolved. Then slowly add 7.6 parts by mass of aluminum hydroxide with a particle size of 0.1 μm. Subsequently, heat to 100 °C, carry out a reaction for 9.5 h, and then carry out vacuum distillation and vacuum drying to obtain the 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide.

[0032] The preparation steps of the ionic liquid-functionalized boron nitride nanosheets are as follows: Put hexagonal boron nitride into a ceramic crucible, heat it to 995 °C in a muffle furnace and keep it for 3.5 h, and naturally cool to room temperature to obtain oxidized hexagonal boron nitride; Add 8 parts by mass of oxidized hexagonal boron nitride to a mixed solution of 170 parts by mass of deionized water and 35 parts by mass of ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate, carry out ultrasonic treatment for 7 h, centrifuge at 7000 rpm for 9 min, take the precipitate, and carry out vacuum drying at 55 °C to obtain the ionic liquid-functionalized boron nitride nanosheets.

[0033] The preparation steps of the toughening agent are as follows: Under nitrogen protection, mix 11 parts by mass of glycidyl acrylate, 14 parts by mass of methacrylate, 2 parts by mass of 4-vinylbenzaldehyde, 29 parts by mass of dioxane, 0.2 parts by mass of isobutanol, and 0.25 parts by mass of benzoyl peroxide, stir evenly and react at 88 °C for 6.5 h, and then cool to room temperature; Drop the obtained copolymer solution into 300 parts by mass of methanol, and powdery precipitation will occur. Let it stand and filter; Carry out vacuum drying of the obtained precipitate at 78 °C for 3.5 h, and pulverize it to obtain the toughening agent.

[0034] (Example 2) A preparation method of a flame-retardant polyester material includes the following preparation steps: (1) Weigh and mix the raw material components according to the following mass fractions: 98 mass fractions of intrinsically flame-retardant polyester resin, 2 mass fractions of ionic liquid-functionalized boron nitride nanosheets, 1 mass fraction of ammonium polyphosphate, 0.8 mass fraction of antioxidant, 0.4 mass fraction of lubricant, 66 mass fractions of calcium carbonate, and 6 mass fractions of toughening agent. (2) First, put the intrinsically flame-retardant polyester resin, ionic liquid-functionalized boron nitride nanosheets, and toughening agent weighed in step (1) into a torque rheometer, and carry out internal mixing and blending at 263 °C and 60 r / min for 6 min. Subsequently, mix with ammonium polyphosphate, antioxidant, lubricant, and calcium carbonate in a high-speed mixer at room temperature at high speed for 13 min, and then add them into a twin-screw extruder. The temperatures of each section of the screw of the twin-screw extruder from the feeding port to the head are 230 °C, 240 °C, 240 °C, 250 °C, 260 °C, 250 °C, 240 °C, 230 °C, and 230 °C respectively, and the screw speed is 400 rpm. Under the conveying and shearing actions of the twin-screw extruder, it is fully melted, plasticized, kneaded and blended, extruded through the head, drawn into strips, cooled, pelletized, dried, and finally packaged.

[0035] The preparation method of the intrinsically flame-retardant polyester resin is as follows: Add 416 mass fractions of 2-acetyl terephthalic acid, 23.25 mass fractions of 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide, 161.37 mass fractions of ethylene glycol, and 0.099 mass fractions of antimony trioxide into a magnetic stirring reactor, and carry out an esterification reaction under nitrogen protection at 0.3 MPa and 235 °C. When the esterification temperature drops to 100 °C, the esterification reaction is completed. After discharging the pressure to atmospheric pressure and the water generated by esterification, react at atmospheric pressure for 30 min; then enter the pre-polycondensation stage, with a vacuum degree of 0.05 MPa, the temperature rises from 235 °C to 275 °C, and the time is 30 min; the final polycondensation is carried out under full vacuum and at a temperature of 275 °C. When the stirring power is 16 kW, the reaction ends, and nitrogen is introduced to discharge the material to obtain the intrinsically flame-retardant polyester resin.

[0036] The preparation steps of the 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide are as follows: Mix 300 mass fractions of deionized water and 10.5 mass fractions of 1-hydroxyethylidene-1,1-diphosphonic acid and stir until the 1-hydroxyethylidene-1,1-diphosphonic acid is dissolved. Then slowly add 7.8 mass fractions of aluminum hydroxide with a particle size of 10 μm, and then heat to 100 °C. After reacting for 10 h, carry out vacuum distillation and vacuum drying to obtain 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide.

[0037] The preparation steps of the ionic liquid-functionalized boron nitride nanosheets are as follows: Put hexagonal boron nitride into a ceramic crucible, heat it to 1000 °C in a muffle furnace and keep it for 4 h, and then naturally cool it to room temperature to obtain oxidized hexagonal boron nitride; Add 8 parts by mass of oxidized hexagonal boron nitride to a mixed solution of 170 parts by mass of deionized water and 36 parts by mass of ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate, ultrasonically treat it for 8 h, centrifuge it at 8000 rpm for 10 min, take the precipitate, and vacuum dry it at 60 °C to obtain ionic liquid-functionalized boron nitride nanosheets.

[0038] The preparation steps of the toughening agent are as follows: Under nitrogen protection, mix 12 parts by mass of glycidyl acrylate, 15 parts by mass of methacrylate, 3 parts by mass of 4-vinylbenzaldehyde, 29.4 parts by mass of dioxane, 0.3 parts by mass of isobutanol and 0.3 parts by mass of benzoyl peroxide, stir evenly and react at 90 °C for 7 h, and then cool to room temperature; Drop the obtained copolymer solution into 300 parts by mass of methanol, and powdery precipitation will occur. Let it stand and filter; Vacuum dry the obtained precipitate at 80 °C for 4 h, and pulverize it to obtain the toughening agent.

[0039] (Example 3) A preparation method of a flame-retardant polyester material includes the following preparation steps: (1) Weigh and mix the raw material components according to the following mass parts: 99 parts by mass of intrinsically flame-retardant polyester resin, 1 part by mass of ionic liquid-functionalized boron nitride nanosheets, 1.1 parts by mass of ammonium polyphosphate, 1 part by mass of antioxidant, 0.5 part by mass of lubricant, 67 parts by mass of calcium carbonate, 7 parts by mass of toughening agent; (2) First, put the intrinsically flame-retardant polyester resin, ionic liquid-functionalized boron nitride nanosheets, and toughening agent weighed in step (1) into a torque rheometer, and carry out intensive mixing and blending at 265 °C and 70 r / min for 9 min. Then, mix them with ammonium polyphosphate, antioxidant, lubricant, and calcium carbonate at room temperature and high speed in a high-speed mixer for 15 min, and then add them to a twin-screw extruder. The temperatures of each section of the screw of the twin-screw extruder from the feeding port to the head are 230 °C, 240 °C, 240 °C, 250 °C, 260 °C, 250 °C, 240 °C, 230 °C, 230 °C respectively, and the screw speed is 400 rpm. Under the conveying and shearing actions of the twin-screw extruder, fully melt and plasticize, knead and mix, extrude through the head, draw into strips, cool, pelletize, dry, and finally package.

[0040] The preparation method of the intrinsically flame-retardant polyester resin is as follows: Add 417 parts by mass of 2-acetyl terephthalic acid, 23.3 parts by mass of 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide, 161.4 parts by mass of ethylene glycol, and 0.100 parts by mass of antimony trioxide into a magnetic stirring reactor, and carry out an esterification reaction under nitrogen protection at 0.35 MPa and 236 °C. When the esterification temperature drops to 100 °C, the esterification reaction is completed. After discharging the pressure to atmospheric pressure and the water generated by esterification, react for 32 min under atmospheric pressure; then enter the pre-polycondensation stage, with a vacuum degree of 0.05 MPa, the temperature rises from 236 °C to 276 °C, and the time is 32 min; the final polycondensation is carried out under full vacuum and at a temperature of 276 °C. When the stirring power is 16 kW, the reaction ends, and nitrogen is introduced to discharge the material to obtain the intrinsically flame-retardant polyester resin.

[0041] The preparation steps of the 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide are as follows: Mix 300 parts by mass of deionized water and 11 parts by mass of 1-hydroxyethylidene-1,1-diphosphonic acid and stir until the 1-hydroxyethylidene-1,1-diphosphonic acid is dissolved. Then slowly add 8.0 parts by mass of aluminum hydroxide with a particle size of 25 μm, and then heat to 100 °C. After reacting for 10.5 h, carry out vacuum distillation and vacuum drying to obtain the 1-hydroxyethylidene-1,1-diphosphonic acid modified aluminum hydroxide.

[0042] The preparation steps of the ionic liquid-functionalized boron nitride nanosheets are as follows: Put hexagonal boron nitride into a ceramic crucible, heat it to 1005 °C in a muffle furnace and keep it for 4.5 h, and naturally cool to room temperature to obtain oxidized hexagonal boron nitride; Add 8 parts by mass of oxidized hexagonal boron nitride to a mixed solution of 170 parts by mass of deionized water and 37 parts by mass of ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate, ultrasonically treat for 9 h, centrifuge at 9000 rpm for 11 min, take the precipitate, and vacuum dry at 65 °C to obtain the ionic liquid-functionalized boron nitride nanosheets.

[0043] The preparation steps of the toughening agent are as follows: Under nitrogen protection, mix 13 parts by mass of glycidyl acrylate, 16 parts by mass of methacrylate, 4 parts by mass of 4-vinylbenzaldehyde, 30 parts by mass of dioxane, 0.3 parts by mass of isobutanol, and 0.35 parts by mass of benzoyl peroxide, stir evenly and react at 92 °C for 7.5 h, and then cool to room temperature; Drop the obtained copolymer solution into 300 parts by mass of methanol, and powdery precipitation will occur. Let it stand and filter; Vacuum dry the obtained precipitate at 82 °C for 4.5 h, and pulverize it to obtain the toughening agent.

[0044] (Comparative Example 1) The difference between Comparative Example 1 and Example 2 is that the flame-retardant polyester material uses PET instead of the intrinsically flame-retardant polyester resin, and the remaining steps and components are the same as those in Example 2.

[0045] (Comparative Example 2) The difference between Comparative Example 2 and Example 2 is that the intrinsically flame-retardant polyester resin used in Comparative Example 2 is obtained by esterification polycondensation of aluminum hydroxide modified with 1-hydroxyethylidene-1,1-diphosphonic acid and terephthalic acid, rather than by esterification polycondensation of aluminum hydroxide modified with 1-hydroxyethylidene-1,1-diphosphonic acid and 2-acetyl terephthalic acid. The remaining steps and components are the same as those in Example 2.

[0046] (Comparative Example 3) The difference between Comparative Example 3 and Example 2 is that the ionic liquid-functionalized boron nitride nanosheets ionic liquid used in Comparative Example 3 is 1-vinyl-3-butylimidazolium tetrafluoroborate instead of the ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate. The remaining steps and components are the same as those in Example 2.

[0047] (Comparative Example 4) The difference between Comparative Example 4 and Example 2 is that the toughening agent used in Comparative Example 4 is ethylene-acrylate-glycidyl methacrylate terpolymer. The remaining steps and components are the same as those in Example 2.

[0048] (Comparative Example 5) The difference between Comparative Example 5 and Example 2 lies in step (2). The step (2) of Comparative Example 5 is as follows: (2) First, weigh the intrinsically flame-retardant polyester resin, ionic liquid-functionalized boron nitride nanosheets, toughening agent, ammonium polyphosphate, antioxidant, lubricant, and calcium carbonate in the high-speed mixer and mix them at high speed at room temperature for 13 min, then add them into the twin-screw extruder. The temperatures of each section of the screw of the twin-screw extruder from the feeding port to the head are 230°C, 240°C, 240°C, 250°C, 260°C, 250°C, 240°C, 230°C, and 230°C respectively, and the screw speed is 400 rpm. Under the conveying and shearing actions of the twin-screw extruder, it is fully melted, plasticized, kneaded and mixed, extruded through the head, drawn into strips, cooled, pelletized, dried, and finally packaged; the remaining steps and components are the same as those in Example 2.

[0049] (Comparative Example 6) The difference between Comparative Example 6 and Example 2 is that ammonium polyphosphate is not added to the flame-retardant polyester material. The remaining steps and components are the same as those in Example 2.

[0050] (Effect Example) Ultraviolet aging resistance: The flame-retardant polyester material samples prepared in Examples 1 to 3 and Comparative Examples 1 to 6 were irradiated with ultraviolet light at a wavelength of 350 nm at room temperature for 48 h, with the sample being 10 cm away from the ultraviolet light source; the ultraviolet aging resistance was measured by the retention rate of tensile strength, and the larger the value, the better the ultraviolet aging resistance; among them, the tensile strength was tested according to GB / T 1040.1-2018.

[0051] The performance test results of the flame-retardant polyester materials prepared in Examples 1-3 and Comparative Examples 1-6 are shown in Table 1 below: Table 1

[0052] As can be seen from Table 1 above, the flame-retardant polyester materials prepared in Examples 1-3 have good flame retardancy, impact resistance, and ultraviolet aging resistance.

[0053] The difference between Comparative Example 1 and Example 2 is that PET is used as the flame-retardant polyester material instead of the intrinsically flame-retardant polyester resin, and the flame-retardant polyester material prepared has weak flame retardancy, impact resistance, and ultraviolet aging resistance.

[0054] The difference between Comparative Example 2 and Example 2 is that the intrinsically flame-retardant polyester resin used is obtained by esterification and polycondensation of aluminum hydroxide modified with 1-hydroxyethylidene-1,1-diphosphonic acid and terephthalic acid instead of by esterification and polycondensation of aluminum hydroxide modified with 1-hydroxyethylidene-1,1-diphosphonic acid and 2-acetyl terephthalic acid, and the impact resistance and ultraviolet aging resistance of the flame-retardant polyester material prepared are weak.

[0055] The difference between Comparative Example 3 and Example 2 is that 1-vinyl-3-butylimidazolium tetrafluoroborate is used as the ionic liquid-functionalized boron nitride nanosheet ionic liquid instead of the ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate, and the impact resistance and ultraviolet aging resistance of the flame-retardant polyester material prepared are weak.

[0056] The difference between Comparative Example 4 and Example 2 is that ethylene-acrylate-glycidyl methacrylate terpolymer is used as the toughening agent, and the impact resistance and ultraviolet aging resistance of the flame-retardant polyester material prepared are weak.

[0057] The difference between Comparative Example 5 and Example 2 is that in step (2), the intrinsically flame-retardant polyester resin, ionic liquid-functionalized boron nitride nanosheets, toughening agent, ammonium polyphosphate, antioxidant, lubricant, and calcium carbonate are directly mixed and then added to a twin-screw extruder for full melting, plasticization, kneading and mixing, extrusion through the die head, strand drawing, cooling, pelletizing, drying, and packaging, without pre-mixing the polyester resin and ionic liquid-functionalized boron nitride nanosheets; the impact resistance and ultraviolet aging resistance of the flame-retardant polyester material prepared are weak.

[0058] The difference between Comparative Example 6 and Example 2 is that ammonium polyphosphate is not added to the flame-retardant polyester material, and the flame retardancy of the flame-retardant polyester material prepared is weak.

[0059] The specific embodiments described above further elaborate on the object, technical solution, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. A flame-retardant polyester material, characterized in that, By mass parts, the raw material components include 97 - 99 mass parts of intrinsically flame - retardant polyester resin, 1 - 3 mass parts of ionic - liquid - functionalized boron nitride nanosheets, 0.9 - 1.1 mass parts of ammonium polyphosphate, 0.4 - 1 mass part of antioxidant, 0.3 - 0.5 mass part of lubricant, 65 - 67 mass parts of calcium carbonate, and 5 - 7 mass parts of toughening agent.

2. The flame-retardant polyester material according to claim 1, wherein The intrinsically flame - retardant polyester resin is obtained by esterification and polycondensation of aluminum hydroxide modified with 1 - hydroxyethylidene - 1,1 - diphosphonic acid with terephthalic acid monomer and ethylene glycol.

3. The flame-retardant polyester material according to claim 2, characterized in that, The terephthalic acid monomer includes at least 2 - acetyl terephthalic acid.

4. The flame-retardant polyester material according to claim 1, wherein The ionic - liquid - functionalized boron nitride nanosheets are obtained by compounding ionic liquid 1 - aminoethyl - 3 - methylimidazolium tetrafluoroborate with hexagonal boron nitride.

5. The flame-retardant polyester material according to claim 1, characterized in that, The toughening agent is obtained by copolymerization of glycidyl acrylate, glycidyl acrylate, and 4 - vinylbenzaldehyde.

6. A method for preparing a flame-retardant polyester material according to any one of claims 1 to 5, characterized in that, It includes the following preparation steps: (1) Weigh and mix each raw material component according to the corresponding mass parts. (2) First, put the intrinsically flame - retardant polyester resin, ionic - liquid - functionalized boron nitride nanosheets, and toughening agent weighed in step (1) into a torque rheometer, and carry out intensive mixing and blending at 260 - 265 °C and 50 - 70 r / min for 3 - 9 min. Then, mix with ammonium polyphosphate, antioxidant, lubricant, and calcium carbonate in a high - speed mixer at room temperature at high speed for 10 - 15 min, and then add them into a twin - screw extruder for full melting, plasticizing, kneading and mixing, extruding through the die head, drawing, cooling, pelletizing, drying, and finally packaging.

7. The preparation method of the flame-retardant polyester material according to claim 6, characterized in that, The preparation method of the intrinsically flame - retardant polyester resin is as follows: Add 415 - 417 mass parts of 2 - acetyl terephthalic acid, 23.2 - 23.3 mass parts of aluminum hydroxide modified with 1 - hydroxyethylidene - 1,1 - diphosphonic acid, 161.3 - 161.4 mass parts of ethylene glycol, and 0.098 - 0.100 mass part of antimony trioxide into a magnetic stirring reactor, and carry out esterification reaction under nitrogen protection at 0.25 - 0.35 MPa and 234 - 236 °C. When the esterification temperature drops to 100 °C, the esterification reaction is completed. After discharging the pressure to atmospheric pressure and the water generated by esterification, react at atmospheric pressure for 28 - 32 min; then enter the pre - polycondensation stage, with a vacuum degree of 0.05 MPa, the temperature rising from 234 - 236 °C to 274 - 276 °C, and the time being 28 - 32 min; the final polycondensation is carried out under full vacuum and at a temperature of 274 - 276 °C. When the stirring power is 16 kW, the reaction ends, and nitrogen is introduced to discharge the material to obtain the intrinsically flame - retardant polyester resin.

8. The preparation method of the flame-retardant polyester material according to claim 7, characterized in that, The preparation steps of the 1 - hydroxyethylidene - 1,1 - diphosphonic acid - modified aluminum hydroxide are as follows: Mix 300 mass parts of deionized water and 10 - 11 mass parts of 1 - hydroxyethylidene - 1,1 - diphosphonic acid and stir until 1 - hydroxyethylidene - 1,1 - diphosphonic acid is dissolved. Then, slowly add 7.6 - 8.0 mass parts of aluminum hydroxide with a particle size of 0.1 - 25 μm. Subsequently, heat to 100 °C, react for 9.5 - 10.5 h, and then carry out vacuum distillation and vacuum drying to obtain 1 - hydroxyethylidene - 1,1 - diphosphonic acid - modified aluminum hydroxide.

9. The preparation method of the flame-retardant polyester material according to claim 6, wherein, The preparation steps of the ionic liquid-functionalized boron nitride nanosheets are as follows: Put hexagonal boron nitride into a ceramic crucible, heat it to 995 - 1005 °C in a muffle furnace and keep it for 3.5 - 4.5 h, and then naturally cool it to room temperature to obtain oxidized hexagonal boron nitride; Add 8 parts by mass of the oxidized hexagonal boron nitride to a mixed solution of 170 parts by mass of deionized water and 35 - 37 parts by mass of ionic liquid 1-aminoethyl-3-methylimidazolium tetrafluoroborate, ultrasonically treat it for 7 - 9 h, centrifuge it at 7000 - 9000 rpm for 9 - 11 min, take the precipitate, and vacuum dry it at 55 - 65 °C to obtain the ionic liquid-functionalized boron nitride nanosheets.

10. The preparation method of the flame-retardant polyester material according to claim 6, characterized in that, The preparation steps of the toughening agent are as follows: Under nitrogen protection, mix 11 - 13 parts by mass of glycidyl acrylate, 14 - 16 parts by mass of methacrylate, 2 - 4 parts by mass of 4-vinylbenzaldehyde, 29 - 30 parts by mass of dioxane, 0.2 - 0.3 parts by mass of isobutanol and 0.25 - 0.35 parts by mass of benzoyl peroxide, stir evenly and react at 88 - 92 °C for 6.5 - 7.5 h, and then cool it to room temperature; Drop the obtained copolymer solution into 300 parts by mass of methanol, and powdery precipitation will occur, let it stand and filter; Vacuum dry the obtained precipitate at 78 - 82 °C for 3.5 - 4.5 h, and pulverize it to obtain the toughening agent.

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