Flame retardant thermoplastic polyester elastomer and method for preparing the same

Abstract

The application discloses a kind of flame-retardant thermoplastic polyester elastomer and preparation method thereof, it is related to polyester elastomer technical field.The flame-retardant thermoplastic polyester elastomer includes the following weight parts of raw materials: thermoplastic polyester elastomer 75-90 parts, polymeric flame retardant 8-15 parts, silicon dioxide 0.8-1.5 parts, coupling agent 0.05-0.1 parts, stabilizer 0.3-1.0 parts, antioxidant 0.1-0.3 parts, lubricant 0.2-0.6 parts;The flame-retardant thermoplastic polyester elastomer prepared by the application has excellent tensile strength, elongation at break and flame-retardant property.

Description

Technical Field

[0001] This invention relates to the field of polyester elastomer technology, specifically to a flame-retardant thermoplastic polyester elastomer and its preparation method. Background Technology

[0002] Thermoplastic polyester elastomers (TPEEs) are typically composed of hard polyester segments and aliphatic polyethers or soft polyester segments. They combine the elasticity of rubber with the processability of thermoplastics, offering advantages such as oil resistance, solvent resistance, flexural fatigue resistance, and resistance to high and low temperatures. They are widely used in the automotive, wire and cable, electronics, and industrial products industries. However, the TPEE molecular structure contains a large number of hydrocarbon segments and ester bonds, resulting in poor inherent flame retardancy. During heating or combustion, TPEE is prone to melting, dripping, and continuous burning. Especially in applications such as wire and cable sheathing, automotive electronic components, and rail transportation components, the material not only needs to meet requirements for mechanical strength, flexibility, and processability, but also requires a high flame retardancy rating, low dripping risk, and good thermal stability. Traditional flame retardant modification methods typically involve adding halogenated flame retardants, inorganic flame retardants, or phosphorus-nitrogen flame retardants to TPEE. Among them, halogenated flame retardants have high flame retardant efficiency, but may release corrosive or toxic fumes during combustion, which does not conform to the development trend of low smoke, halogen-free, and environmentally friendly products; inorganic flame retardants such as magnesium hydroxide and aluminum hydroxide, although halogen-free and low smoke, usually require a high addition amount to achieve the ideal flame retardant effect, which is not conducive to maintaining the original flexibility and elasticity of TPEE; intumescent flame retardants such as ammonium polyphosphate, although they can improve flame retardant performance through the synergistic effect of gas source and carbon source, have strong polarity and insufficient compatibility with TPEE, which can easily affect the surface quality, processing stability and hydrolysis resistance of the material; some small molecule phosphorus and nitrogen flame retardants have problems of migration, precipitation and insufficient heat resistance during processing or long-term use.

[0003] Chinese invention patent CN119823538A discloses a halogen-free flame-retardant thermoplastic polyester elastomer and its preparation method. The halogen-free flame-retardant thermoplastic polyester elastomer comprises the following parts by weight: 100 parts of polyether ester type TPEE, 10-30 parts of polymeric phosphorus-based flame retardant, 0.3-0.8 parts of anti-drip agent, 0.2-0.6 parts of heat-stabilizing agent, and 0.2-0.5 parts of ultraviolet absorber. This invention, through the design of the specific composition of the halogen-free flame-retardant thermoplastic polyester elastomer, yields a halogen-free flame-retardant thermoplastic polyester elastomer with good flame retardancy, but its mechanical properties need further improvement. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the purpose of this invention is to provide a flame-retardant thermoplastic polyester elastomer and its preparation method.

[0005] A flame-retardant thermoplastic polyester elastomer comprises the following raw materials in parts by weight:

[0006] The composition includes 75-90 parts thermoplastic polyester elastomer, 8-15 parts polymeric flame retardant, 0.8-1.5 parts silica, 0.05-0.1 parts coupling agent, 0.3-1.0 parts stabilizer, 0.1-0.3 parts antioxidant, and 0.2-0.6 parts lubricant.

[0007] The polymeric flame retardant has the following structural formula:

[0008] .

[0009] The coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

[0010] The stabilizer is polycarbodiimide.

[0011] The antioxidant is one of antioxidant 1010 and antioxidant 1076.

[0012] The lubricant is one of zinc stearate and ethylene bis-stearamide.

[0013] The polymeric flame retardant is prepared by the following method:

[0014] 9,10-Dihydro-9-oxa-10-[N,N-bis-(2-hydroxyethylaminomethyl)]-10-phosphaphenanthrene-10-oxide reacts with dimethyl terephthalate under the action of a catalyst, and then reacts with lipoic acid under the action of a condensing agent to obtain a polymeric flame retardant; the reaction equation is shown below:

[0015]

[0016] It should be noted that the above reaction equations are only used to illustrate the reaction relationships between the functional groups. In the actual preparation process, by controlling the molar ratio of 9,10-dihydro-9-oxa-10-[N,N-bis-(2-hydroxyethylaminomethyl)]-10-phosphaphenanthrene-10-oxide to dimethyl terephthalate, a hydroxyl-terminated polymer is obtained. Furthermore, by controlling the molar ratio of the carboxyl group of lipoic acid to the hydroxyl group of the polymer, the hydroxyl groups at both ends of the polymer react with the carboxyl groups in the lipoic acid molecule, thereby introducing lipoic acid functional structures at both ends of the polymer molecule, resulting in a double-terminated modified polymeric flame retardant.

[0017] The catalyst is tetrabutyl titanate.

[0018] The condensing agent is 4-dimethylaminopyridine and dicyclohexylcarbodiimide.

[0019] The molar ratio of 9,10-dihydro-9-oxa-10-[N,N-bis-(2-hydroxyethylaminomethyl)]-10-phosphaphenanthrene-10-oxide to dimethyl terephthalate and dimethyl terephthalate to thioctic acid is (1.1-1.2):1:(0.25-0.5).

[0020] A method for preparing a flame-retardant thermoplastic polyester elastomer includes the following steps:

[0021] (1) Weigh out the following by weight: 75-90 parts of thermoplastic polyester elastomer, 8-15 parts of polymeric flame retardant, 0.8-1.5 parts of silica, 0.05-0.1 parts of coupling agent, 0.3-1.0 parts of stabilizer, 0.1-0.3 parts of antioxidant, and 0.2-0.6 parts of lubricant;

[0022] (2) After mixing the aqueous ethanol solution with silica, ultrasonication was used to obtain a silica dispersion; the aqueous ethanol solution and coupling agent were mixed evenly, the pH was adjusted to 4.5-5.5, and added to the silica dispersion. The mixture was heated to react and modified silica was obtained.

[0023] (3) After mixing thermoplastic polyester elastomer, polymeric flame retardant, modified silica, stabilizer, antioxidant and lubricant, stir and mix at room temperature, add to twin-screw extruder, and after blending, extrusion, cooling and pelletizing, flame retardant thermoplastic polyester elastomer is obtained.

[0024] Due to the adoption of the above technical solutions, the beneficial effects of the present invention include:

[0025] The flame-retardant thermoplastic polyester elastomer prepared by this invention has excellent tensile strength, elongation at break and flame retardant properties. Attached Figure Description

[0026] Figure 1 Fourier transform infrared spectra of 9,10-dihydro-9-oxa-10-[N,N-bis-(2-hydroxyethylaminomethyl)]-10-phosphaphenanthrene-10-oxide and polymeric flame retardant prepared in Example 2. Detailed Implementation

[0027] Example 1: Preparation of 9,10-dihydro-9-oxa-10-[N,N-bis-(2-hydroxyethylaminomethyl)]-10-phosphaphenanthrene-10-oxide (DOPO-DAM)

[0028] 200 ml of anhydrous ethanol, 0.1 mol of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), and 0.105 mol of diethanolamine were sequentially added to a reaction flask, stirred and mixed, heated to 50 °C, and 3.6 g of paraformaldehyde was added. The mixture was then refluxed for 8 h, cooled to room temperature, and rotary evaporated at 50 °C to constant weight. 150 ml of diethyl ether was added and stirred, and the mixture was cooled to 0 °C and allowed to stand for 5 h to precipitate. The precipitate was filtered, and a mixture of diethyl ether and anhydrous ethanol (V) was used. 乙醚 V 无水乙醇 Wash with a 3:1 ratio (2×50ml), dry under vacuum at 50℃ for 12h to obtain DOPO-DAM. The reaction equation is shown below:

[0029]

[0030] Its 1H NMR data are as follows: 1 H NMR (400 MHz, DMSO-d6) δ 8.12 – 8.07 (m, 1H), 8.03 – 7.97 (m, 2H), 7.66 – 7.60 (m, 1H), 7.58 – 7.43 (m, 3H), 7.41 – 7.35(m, 1H), 3.96 – 3.85 (m, 2H), 3.57 – 3.50 (m, 6H), 2.82 – 2.65 (m, 4H); HRMS(m / z): 334.1135[M+H] + .

[0031] Example 2 Preparation of Polymerized Flame Retardant

[0032] Under nitrogen protection, 300 ml of xylene, 0.11 mol of DOPO-DAM (prepared in Example 1), 0.1 mol of dimethyl terephthalate, and 0.2 g of tetrabutyl titanate were added to a reaction flask, stirred and mixed, and heated to reflux for 4 h. During the reaction, methanol generated was continuously removed through a methanol receiving device. After cooling to room temperature, the reaction solution was slowly added to 400 ml of anhydrous ethanol, stirred to precipitate, filtered, and the filter cake was washed successively with anhydrous ethanol (3 × 50 ml) to obtain the polymer. 600 ml of dichloromethane, all of the polymer obtained above, 0.025 mol of lipoic acid, and 0.03 mol of... 4-Dimethylaminopyridine was added to a reaction flask and stirred until homogeneous. 0.03 mol of dicyclohexylcarbodiimide was added, and the mixture was stirred and reacted at room temperature for 20 h. The mixture was filtered, and the filtrate was rotary evaporated at 35 °C to constant weight. 500 ml of cold diethyl ether was slowly added and stirred to precipitate the precipitate. The precipitate was filtered, and the filter cake was washed with cold methanol (3 × 50 ml). The cake was then vacuum dried at 50 °C for 12 h to obtain a polymeric flame retardant with a number average molecular weight of 5293.

[0033] Figure 1 The Fourier transform infrared spectra of DOPO-DAM, polymers, and polymeric flame retardants are shown in the figure. As can be seen from the figure, DOPO-DAM exhibits high activity in the 3300-3400 cm⁻¹ range. -1 A broad and strong OH stretching vibration peak appears at 2920 and 2850 cm⁻¹. -1 These are peaks for the CH stretching vibration of fatty acids, at 1230 and 1200 cm⁻¹. -1 The strong absorption peak at 1100-1050 cm⁻¹ is the P=O stretching vibration peak of the DOPO structure. -1 The peaks are the stretching vibration peaks of POC, CO, and CN, at 750-700 cm⁻¹. -1 The peak represents the out-of-plane bending vibration of the aromatic ring CH, and it is not present in the 2350-2440 cm⁻¹ range. -1 The observation of stretching vibration peaks of the PH bond in the region indicates that the target intermediate A has been successfully synthesized. The polymer exhibits peaks at 1720-1735 cm⁻¹. -1 A strong and sharp new peak of ester group C=O stretching vibration appears at 1270-1240 cm⁻¹. -1 An asymmetric stretching peak of ester-COC appears at 730-720 cm⁻¹. -1 The presence of characteristic peaks of the para-substituted benzene ring and the decrease in intensity of the OH peak indicate that the hydroxyl group of intermediate A underwent a successful polycondensation reaction with the ester group of dimethyl terephthalate, generating a polyester polyol containing a DOPO side group. The polymeric flame retardant exhibits activity at 3300-3400 cm⁻¹. -1 The OH absorption peak basically disappeared, while the absorption peak at 700-650 cm⁻¹ disappeared. -1 Weak CS stretching vibrations occur, in the range of 510-540 cm. -1 The characteristic weak absorption peak of the SS bond in the five-membered ring of lipoic acid can be observed nearby, while the characteristic peak of P=O of DOPO is still retained, proving that lipoic acid has been successfully grafted onto the polymer chain, and proving that the polymeric flame retardant has been successfully prepared.

[0034] Example 3 Preparation of Polymerized Flame Retardant

[0035] Under nitrogen protection, 300 ml of xylene, 0.115 mol DOPO-DAM (prepared in Example 1), 0.1 mol dimethyl terephthalate, and 0.2 g tetrabutyl titanate were added to a reaction flask, stirred and mixed, and heated to reflux for 5 h. During the reaction, methanol generated was continuously removed through a methanol receiving device. After cooling to room temperature, the reaction solution was slowly added to 400 ml of anhydrous ethanol, stirred to precipitate, filtered, and the filter cake was washed successively with anhydrous ethanol (3 × 50 ml) to obtain the polymer. 600 ml of dichloromethane, the polymer, 0.04 mol lipoic acid, and 0.05 mol... 4-Dimethylaminopyridine was added to a reaction flask and stirred until homogeneous. 0.05 mol of dicyclohexylcarbodiimide was added, and the mixture was stirred and reacted at room temperature for 22 h. The mixture was filtered, and the filtrate was rotary evaporated at 35 °C to constant weight. 500 ml of cold diethyl ether was slowly added and stirred to precipitate the precipitate. The precipitate was filtered, and the filter cake was washed with cold methanol (3 × 50 ml). The cake was then vacuum dried at 50 °C for 12 h to obtain a polymeric flame retardant with a number average molecular weight of 3748.

[0036] Example 4 Preparation of Polymerized Flame Retardants

[0037] Under nitrogen protection, 300 ml of xylene, 0.12 mol DOPO-DAM (prepared in Example 1), 0.1 mol dimethyl terephthalate, and 0.2 g tetrabutyl titanate were added to a reaction flask, stirred and mixed, and heated to reflux for 6 h. During the reaction, methanol generated was continuously removed through a methanol receiving device. After cooling to room temperature, the reaction solution was slowly added to 400 ml of anhydrous ethanol, stirred to precipitate, filtered, and the filter cake was washed successively with anhydrous ethanol (3 × 50 ml) to obtain the polymer. 600 ml of dichloromethane, the polymer, 0.05 mol lipoic acid, and 0.06 mol... 4-Dimethylaminopyridine was added to a reaction flask and stirred until homogeneous. 0.06 mol of dicyclohexylcarbodiimide was added, and the mixture was stirred and reacted at room temperature for 24 h. The mixture was filtered, and the filtrate was rotary evaporated at 35 °C to constant weight. 500 ml of cold diethyl ether was slowly added and stirred to precipitate the precipitate. The precipitate was filtered, and the filter cake was washed with cold methanol (3 × 50 ml). The cake was then dried under vacuum at 50 °C for 12 h to obtain a polymeric flame retardant with a number average molecular weight of 2976.

[0038] Example 5 Preparation of flame-retardant thermoplastic polyester elastomer

[0039] (1) Weigh out: 750g of thermoplastic polyester elastomer, 80g of polymeric flame retardant (prepared in Example 2), 8g of silica, 0.5g of coupling agent (γ-(2,3-epoxypropoxy)propyltrimethoxysilane), 3g of stabilizer (polycarbodiimide), 1g of antioxidant (antioxidant 1010), and 2g of lubricant (zinc stearate);

[0040] (2) Mix 100 ml of 90 wt% ethanol aqueous solution with silica and sonicate at 30 kHz and 200 W for 30 min to obtain silica dispersion; mix 10 ml of 90 wt% ethanol aqueous solution and coupling agent evenly, adjust pH to 4.5 with acetic acid, stir for 20 min, add to silica dispersion, stir and heat to 60 ℃ for 4 h, cool to room temperature, filter, wash with 90 wt% ethanol aqueous solution (2 × 50 ml), and vacuum dry at 80 ℃ for 8 h to obtain modified silica;

[0041] (3) After mixing thermoplastic polyester elastomer, polymeric flame retardant, modified silica, stabilizer, antioxidant and lubricant, stir at 500 rpm for 20 min at room temperature, add to twin screw extruder, screw speed 360 r / min; feed section temperature 160℃, melt section temperature 200℃, mixing section temperature 210℃, extrusion section temperature 220℃, cool to room temperature in water tank, pelletize, vacuum dry at 80℃ for 6 h to obtain flame retardant thermoplastic polyester elastomer.

[0042] Example 6 Preparation of flame-retardant thermoplastic polyester elastomer

[0043] (1) Weigh out: 800g of thermoplastic polyester elastomer, 120g of polymeric flame retardant (prepared in Example 3), 12g of silica, 0.8g of coupling agent (γ-(2,3-epoxypropoxy)propyltrimethoxysilane), 8g of stabilizer (polycarbodiimide), 2g of antioxidant (antioxidant 1010), and 4g of lubricant (zinc stearate);

[0044] (2) Mix 100 ml of 90 wt% ethanol aqueous solution with silica and sonicate at 30 kHz and 200 W for 30 min to obtain silica dispersion; mix 10 ml of 90 wt% ethanol aqueous solution and coupling agent evenly, adjust pH to 5 with acetic acid, stir for 20 min, add to silica dispersion, stir and heat to 60 ℃ for 4 h, cool to room temperature, filter, wash with 90 wt% ethanol aqueous solution (2 × 50 ml), and vacuum dry at 100 ℃ for 8 h to obtain modified silica;

[0045] (3) After mixing thermoplastic polyester elastomer, polymeric flame retardant, modified silica, stabilizer, antioxidant and lubricant, stir at 500 rpm for 20 min at room temperature, add to twin screw extruder, screw speed 360 r / min; feed section temperature 160℃, melt section temperature 200℃, mixing section temperature 210℃, extrusion section temperature 220℃, cool to room temperature in water tank, pelletize, vacuum dry at 80℃ for 6 h to obtain flame retardant thermoplastic polyester elastomer.

[0046] Example 7 Preparation of flame-retardant thermoplastic polyester elastomer

[0047] (1) Weigh out: 900g of thermoplastic polyester elastomer, 150g of polymeric flame retardant (prepared in Example 4), 15g of silica, 1g of coupling agent (γ-(2,3-epoxypropoxy)propyltrimethoxysilane), 10g of stabilizer (polycarbodiimide), 3g of antioxidant (antioxidant 1076), and 6g of lubricant (ethylene bis-stearamide);

[0048] (2) Mix 100 ml of 90 wt% ethanol aqueous solution with silica and sonicate at 30 kHz and 200 W for 30 min to obtain silica dispersion; mix 100 ml of 90 wt% ethanol aqueous solution and coupling agent evenly, adjust pH to 5.5 with acetic acid, stir for 20 min, add to silica dispersion, stir and heat to 60 ℃ for 4 h, cool to room temperature, filter, wash with 90 wt% ethanol aqueous solution (2 × 50 ml), and vacuum dry at 100 ℃ for 8 h to obtain modified silica;

[0049] (3) After mixing thermoplastic polyester elastomer, polymeric flame retardant, modified silica, stabilizer, antioxidant and lubricant, stir at 500 rpm for 20 min at room temperature, add to twin screw extruder, screw speed 360 r / min; feed section temperature 160℃, melt section temperature 200℃, mixing section temperature 210℃, extrusion section temperature 220℃, cool to room temperature in water tank, pelletize, vacuum dry at 80℃ for 6 h to obtain flame retardant thermoplastic polyester elastomer.

[0050] Comparative Example 1

[0051] Preparation of flame-retardant thermoplastic polyester elastomers

[0052] (1) Weigh out: 800g of thermoplastic polyester elastomer, 120g of polymeric flame retardant (prepared in Example 2), 12g of silica, 0.8g of coupling agent (γ-(2,3-epoxypropoxy)propyltrimethoxysilane), 8g of stabilizer (polycarbodiimide), 2g of antioxidant (antioxidant 1010), and 4g of lubricant (zinc stearate);

[0053] (2) After mixing thermoplastic polyester elastomer, polymeric flame retardant, silica, coupling agent, stabilizer, antioxidant and lubricant, stir at 500 rpm for 20 min at room temperature, add to twin-screw extruder, screw speed 360 r / min; feed section temperature 160℃, melt section temperature 200℃, mixing section temperature 210℃, extrusion section temperature 220℃, cool to room temperature in water tank, pelletize, vacuum dry at 80℃ for 6 h to obtain flame retardant thermoplastic polyester elastomer.

[0054] Comparative Example 2

[0055] The raw material composition and preparation method of the flame-retardant thermoplastic polyester elastomer are basically the same as those in Example 6, except that the polymeric flame retardant is replaced with an equal weight of DOPO-DAM.

[0056] Comparative Example 3

[0057] The raw material composition and preparation method of the flame-retardant thermoplastic polyester elastomer are basically the same as those in Example 6, except that the polymeric flame retardant is replaced with an equal weight of polymeric flame retardant prepared by the following method:

[0058] The preparation method of the polymeric flame retardant is basically the same as that in Example 3, except that DOPO-DAM is used to replace an equimolar amount of the flame retardant crosslinking agent prepared by the following method:

[0059] 200 ml of anhydrous ethanol, 0.1 mol of ethyl phenylphosphonate, and 0.105 mol of diethanolamine were added sequentially to a reaction flask and stirred until homogeneous. The mixture was heated to 50 °C, and 3.6 g of paraformaldehyde was added. The mixture was then heated to reflux and reacted for 8 hours. After cooling to room temperature, the mixture was rotary evaporated at 50 °C to constant weight. 150 ml of diethyl ether was added and stirred. The mixture was cooled to 0 °C and allowed to stand for 5 hours to precipitate. The precipitate was filtered, and a mixture of diethyl ether and anhydrous ethanol (V) was used. 乙醚 V 无水乙醇 Wash with a 3:1 ratio (2×50ml), and vacuum dry at 50℃ for 12h to obtain a flame-retardant crosslinking agent.

[0060] Comparative Example 4

[0061] The raw material composition and preparation method of the flame-retardant thermoplastic polyester elastomer are basically the same as those in Example 6, except that the polymeric flame retardant is replaced with an equal weight of polymeric flame retardant prepared by the following method:

[0062] The preparation method of the polymeric flame retardant is basically the same as that in Example 3, except that DOPO-DAM is replaced with 0.15 mol and lipoic acid is replaced with 0.06 mol.

[0063] Comparative Example 5

[0064] The raw material composition and preparation method of the flame-retardant thermoplastic polyester elastomer are basically the same as those in Example 6, except that the polymeric flame retardant is replaced with an equal weight of polymeric flame retardant prepared by the following method:

[0065] The preparation method of the polymeric flame retardant is basically the same as that in Example 3, except that dimethyl terephthalate is replaced with an equimolar amount of dimethyl succinate.

[0066] Comparative Example 6

[0067] The raw material composition and preparation method of the flame-retardant thermoplastic polyester elastomer are basically the same as those in Example 6, except that the polymeric flame retardant is replaced with an equal weight of polymeric flame retardant prepared by the following method:

[0068] The preparation method of the polymeric flame retardant is basically the same as that in Example 3, except that dimethyl terephthalate is replaced with an equimolar amount of dimethyl biphenyl ester.

[0069] Comparative Example 7

[0070] The raw material composition and preparation method of the flame-retardant thermoplastic polyester elastomer are basically the same as those in Example 6, except that the polymeric flame retardant is replaced with an equal weight of polymeric flame retardant prepared by the following method:

[0071] The preparation method of the polymeric flame retardant is basically the same as that in Example 3, except that lipoic acid is replaced with an equimolar amount of 4-(methyl disulfide)butyric acid (CAS: 138148-60-4).

[0072] The thermoplastic polyester elastomer used in the embodiments and comparative examples of this application is model HP5001, manufactured by Shanghai Yitan New Material Technology Co., Ltd., and dried at 110°C for 3 hours before use; the silica is model HN-SP30S, manufactured by Hangzhou Hengge Nanotechnology Co., Ltd.; and the polycarbodiimide is model UN-03.

[0073] The flame-retardant thermoplastic polyester elastomers prepared in the examples and comparative examples were tested for tensile strength, elongation at break, and flame retardant properties.

[0074] Sample preparation: The thermoplastic polyester elastomers prepared in the examples and comparative examples were dried in a forced-air drying oven at 110°C for 5 hours, and then injection molded into the samples required for testing. The temperatures from the feed port to the nozzle were set as follows: 180°C; 200°C; 220°C; 220°C; and the injection speed was 3.6 cm / s. 3 / s; Injection pressure is 50MPa, holding pressure is 80% of injection pressure, and cooling time is 20s.

[0075] Tensile strength and elongation at break tests: The sample mold dimensions are as follows: total length 170 mm, end width 20 mm, narrow parallel section width 10.0 mm, narrow parallel section length 80 mm, transition arc radius 24 mm, and standard thickness 4.0 mm; the test is conducted using a CMT4104 universal tensile testing machine at a tensile rate of 50 mm / min; the samples are conditioned for 24 hours at 23℃ and relative humidity 50±10% before testing; each test group consists of no fewer than 5 parallel samples, and the average value is taken.

[0076] Flame retardant performance test: The sample mold size is 80mm×10mm×4mm. The limiting oxygen index is tested according to GB / T 2406.2-2009 standard. Before the test, the sample is conditioned in an environment of 23℃ and 50±10% relative humidity for 24 hours. Each group of tests shall have no less than 5 parallel samples and the average value shall be taken.

[0077] Table 1 Performance Test Data

[0078]

[0079] As can be seen from the data in Table 1, the flame-retardant thermoplastic polyester elastomer prepared by the present invention has excellent tensile strength, elongation at break and flame retardant properties.

[0080] The flame-retardant thermoplastic polyester elastomer prepared in this application exhibits excellent performance, mainly due to the synergistic effect between the polymeric flame retardant, modified silica, and TPEE matrix. The polymeric flame retardant, with polyester segments as its main backbone, has good compatibility with the structure of thermoplastic polyester elastomer, maintaining good mechanical properties. The rigid phosphine heterocycle possesses high thermal stability and flame-retardant activity, promoting matrix dehydration and char formation during combustion, and releasing phosphorus-containing free radicals to capture active free radicals such as H· and OH·, while simultaneously playing a role in gas-phase flame suppression and condensed-phase char formation. The five-membered disulfide ring structure participates in char layer stabilization during heating, making the char layer formed after combustion more continuous and dense. Furthermore, the disulfide ring structure can participate in dynamic sulfur bond exchange under heating or shear conditions, improving the interfacial buffering capacity of the system through energy dissipation and reducing embrittlement caused by the rigid flame-retardant structure. After modification with epoxy silane coupling agents, silica can be more uniformly dispersed in the TPEE system, reducing stress concentration caused by inorganic particle agglomeration. The epoxy end can react with active groups (such as hydroxyl and carboxyl groups) in the matrix, improving interfacial compatibility and thus enhancing the mechanical properties of the material. Inorganic silica can also act as a barrier to the transfer of heat, oxygen, and combustible volatiles during combustion, synergistically improving flame retardant performance with polymeric flame retardants. In addition, polycarbodiimide can inhibit the hydrolytic degradation of polyester segments, and antioxidants and lubricants help improve melt processing stability.

[0081] In Comparative Example 1, the silica was not modified, making it difficult for the coupling agent to fully hydrolyze and graft onto the silica surface during melt extrusion. This resulted in reduced silica dispersibility and interfacial bonding, leading to decreased mechanical and flame-retardant properties of the material. In Comparative Example 2, the flame retardant had a small molecular weight, making it prone to migration and exhibiting poor compatibility with the matrix, further degrading the material's mechanical properties. In Comparative Example 3, DOPO was replaced with ethyl phenylphosphonate, lacking the rigid phosphine heterocyclic structure of DOPO, resulting in weakened phosphorus-containing flame-retardant efficiency and char-forming promotion. In Comparative Example 4, the amount of the polymeric flame retardant DOPO-DAM was too high, reducing the molecular weight and structural regularity of the resulting polymeric flame retardant and worsening its compatibility with TPEE, leading to decreased mechanical and flame-retardant properties. In Comparative Example 5, the polymeric flame retardant incorporated flexible aliphatic segments, lacking a rigid benzene ring structure, resulting in reduced tensile strength and char-forming ability. The introduction of biphenyl structures into the polymeric flame retardant used in Comparative Example 6 is beneficial for flame retardancy and char formation, but its structure differs significantly from the matrix, leading to decreased compatibility and reduced mechanical properties. The polymeric flame retardant used in Comparative Example 7 lacks a five-membered disulfide ring, making it difficult to effectively improve mechanical properties through dynamic sulfur bond exchange.

[0082] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. However, any modifications, alterations, and variations made by those skilled in the art without departing from the scope of the present invention based on the disclosed technical content are equivalent embodiments of the present invention. Furthermore, any modifications, alterations, and variations made to the above embodiments based on the essential technology of the present invention are still within the protection scope of the present invention.

Claims

1. A flame-retardant thermoplastic polyester elastomer, characterized in that, The ingredients include the following parts by weight: The composition includes 75-90 parts thermoplastic polyester elastomer, 8-15 parts polymeric flame retardant, 0.8-1.5 parts silica, 0.05-0.1 parts coupling agent, 0.3-1.0 parts stabilizer, 0.1-0.3 parts antioxidant, and 0.2-0.6 parts lubricant. The polymeric flame retardant has the following structural formula: 。 2. The flame-retardant thermoplastic polyester elastomer according to claim 1, characterized in that, The coupling agent is γ-(2,3-epoxypropoxy)propyltrimethoxysilane.

3. The flame-retardant thermoplastic polyester elastomer according to claim 1, characterized in that, The stabilizer is polycarbodiimide.

4. The flame-retardant thermoplastic polyester elastomer according to claim 1, characterized in that, The antioxidant is one of antioxidant 1010 and antioxidant 1076.

5. The flame-retardant thermoplastic polyester elastomer according to claim 1, characterized in that, The lubricant is one of zinc stearate and ethylene bis-stearamide.

6. The flame-retardant thermoplastic polyester elastomer according to claim 1, characterized in that, The polymeric flame retardant is prepared by the following method: A polymeric flame retardant is obtained by reacting 9,10-dihydro-9-oxa-10-[N,N-bis-(2-hydroxyethylaminomethyl)]-10-phosphaphenanthrene-10-oxide with dimethyl terephthalate under the action of a catalyst, followed by reaction with thioctic acid under the action of a condensing agent.

7. The flame-retardant thermoplastic polyester elastomer according to claim 6, characterized in that, The catalyst is tetrabutyl titanate.

8. The flame-retardant thermoplastic polyester elastomer according to claim 6, characterized in that, The condensing agent is 4-dimethylaminopyridine and dicyclohexylcarbodiimide.

9. A flame-retardant thermoplastic polyester elastomer according to claim 6, characterized in that, The molar ratio of 9,10-dihydro-9-oxa-10-[N,N-bis-(2-hydroxyethylaminomethyl)]-10-phosphaphenanthrene-10-oxide to dimethyl terephthalate and dimethyl terephthalate to thioctic acid is (1.1-1.2):1:(0.25-0.5).

10. A method for preparing a flame-retardant thermoplastic polyester elastomer as described in any one of claims 1-9, characterized in that, Includes the following steps: (1) Weigh out the following by weight: 75-90 parts of thermoplastic polyester elastomer, 8-15 parts of polymeric flame retardant, 0.8-1.5 parts of silica, 0.05-0.1 parts of coupling agent, 0.3-1.0 parts of stabilizer, 0.1-0.3 parts of antioxidant, and 0.2-0.6 parts of lubricant; (2) After mixing the aqueous ethanol solution with silica, ultrasonication was used to obtain a silica dispersion; the aqueous ethanol solution and coupling agent were mixed evenly, the pH was adjusted to 4.5-5.5, and added to the silica dispersion. The mixture was heated to react and modified silica was obtained. (3) After mixing thermoplastic polyester elastomer, polymeric flame retardant, modified silica, stabilizer, antioxidant and lubricant, stir and mix at room temperature, add to twin-screw extruder, and after blending, extrusion, cooling and pelletizing, flame retardant thermoplastic polyester elastomer is obtained.

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