Flame-retardant anti-dripping polyester and preparation method thereof

Abstract

The invention relates to the technical field of polyester synthesis, and discloses flame-retardant anti-dripping polyester and a preparation method thereof. Synthetic monomers of the flame-retardant anti-dripping polyester comprise terephthalic acid, ethylene glycol, a flame retardant a and a flame retardant b, the flame retardant a is 2-carboxyethyl phenyl hypophosphorous acid, and the flame retardant b is [(6-oxo-6H-dibenzo [C, E] [1, 2] oxophosphahexane-6-yl) methyl] succinic acid and / or 2-(diphenyl phosphoryl methyl) succinic acid. According to the invention, the specific flame retardant a and flame retardant b are matched for use and can play roles in an initial combustion stage and a sustained combustion stage respectively, so that the polyester can have better flame retardance and molten drop resistance.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester synthesis, in particular to a flame-retardant and anti-drip polyester and a preparation method thereof. Background Art

[0002] Indoor textile combustion is a significant cause of residential fires, resulting in casualties and property damage. Polyester (PET) is one of the most commonly used chemical textile fibers. However, its limiting oxygen index is only 21-22%. Combustion releases significant amounts of heat and toxic smoke, and severe dripping accelerates the spread of fire, causing secondary hazards such as burns. In recent years, with the restructuring and optimization of the textile industry chain and the continuous expansion of its application areas, the market has placed higher expectations on the performance of flame-retardant polyester textiles. Improving the flame retardancy and anti-drip properties of polyester fibers, while reducing the flammability and flame spread rate of textiles, are pressing issues to be addressed.

[0003] The method for improving the flame retardant and anti-melting droplet performance of polyester fibers mainly includes copolymerization, blending or finishing. Among them, the flame retardant efficiency of the additive flame retardant introduced by the blending method is low, resulting in a higher required addition amount, and the flame retardant bound to the fabric by the finishing method is not washable, resulting in poor durability of the flame retardant and anti-melting droplet performance of the fabric. The copolymerization method introduces the flame retardant into the polyester molecular chain through the reaction between the flame retardant and the polyester monomer. Compared with the blending method and the finishing method, it has the advantages of high flame retardant efficiency and lasting flame retardant and anti-melting droplet performance. However, the most commonly used reactive flame retardant in polyester is 2-carboxyethylphenylphosphinate (CEPPA), such as patent CN109706542A, CEPPA participates in the copolymerization synthesis of polyester through hypophosphite groups and carboxyl groups, introduces phosphorus-containing groups into the polyester main chain, cracks in the early stage of combustion, causes the polymer chain to break and reduce melt strength, and achieves flame retardant effect by generating a large amount of molten droplets to take away heat, which will cause the anti-melting droplet performance of polyester to be poor, increasing the risk of secondary disasters. Summary of the Invention

[0004] To address the technical problem that existing reactive flame retardants make it difficult to impart both good flame retardancy and anti-drip properties to polyester, the present invention provides a flame-retardant and anti-drip polyester and a method for preparing the same. By employing a specific reactive flame retardant, the present invention enables polyester to impart both good flame retardancy and anti-drip properties.

[0005] The specific technical solutions of the present invention are: In a first aspect, the present invention provides a flame retardant anti-melting polyester, which is copolymerized from synthetic monomers including terephthalic acid, ethylene glycol, 2-carboxyethylphenyl hypophosphite and 2-(diphenylphosphinomethyl)succinic acid.

[0006] The structural formula of "2-(diphenylphosphorylmethyl)succinic acid" described in the present invention is as follows:

[0007] In the present invention, two reactive flame retardants, 2-carboxyethylphenyl hypophosphorous acid (abbreviated as "CEPPA" in the present invention) and 2-(diphenylphosphorylmethyl)succinic acid (abbreviated as "DPO-ITA" in the present invention), are used. The phosphorus-containing groups introduced into the polyester by the two can produce the following coordinated effects: in the initial combustion stage, the phosphorus-containing groups introduced into the polyester by DPO-ITA are preferentially decomposed by heat to generate acid sources and phosphorus free radicals, wherein the phosphoric acid source acts as a dehydrating agent to promote carbonization, and while absorbing heat to prevent further combustion of the combustible gas, a protective carbon layer can be formed on the polyester surface to prevent the combustion of the combustible gas. The phosphorus radicals impede oxygen diffusion and heat and mass transfer between the gas and solid phases. Phosphorus radicals capture active free radicals in the combustion flame zone, slowing the combustion reaction and exerting a flame retardant effect in the condensed and gas phases first, producing a flame retardant effect while maintaining the integrity of the main chain. In the subsequent sustained combustion stage, the phosphorus-containing groups introduced by CEPPA into the polyester decompose, also generating acid sources and free radicals. The acid source promotes carbonization to make up for the insufficient thickness and area of the carbon layer in the first stage, strengthening the condensed phase barrier effect. The high content of free radicals reacts with a large amount of concentrated H· or HO· to prevent sustained combustion. In this way, the CEPPA and DPO-ITA used in the present invention cooperate with each other to give the polyester better flame retardant and anti-melting properties.

[0008] In addition, the phenylphosphonic acid structure in the DPO-ITA used in the present invention has high heat resistance and hydrolysis resistance, and can have good polymerization stability and a high copolymerization grafting rate during the copolymerization process into polyester. At the same time, DPO-ITA and CEPPA have good compatibility. These properties of DPO-ITA enable the combination of DPO-ITA + CEPPA to impart polyester with better flame retardancy and anti-dripping properties.

[0009] Preferably, the molar ratio of the 2-carboxyethylphenylphosphinoic acid to the 2-(diphenylphosphorylmethyl)succinic acid is 1:0.3-3, calculated based on phosphorus element.

[0010] Preferably, the total amount of the 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid is 5000-12000 ppm of the mass (theoretical production amount) of the flame retardant and anti-drip polyester, calculated as phosphorus element.

[0011] Preferably, the flame retardant anti-drip polyester further comprises a silicon-based anti-drip agent; the amount of the silicon-based anti-drip agent is 2500-10000 ppm of the mass (theoretical production amount) of the flame retardant anti-drip polyester, calculated as silicon element.

[0012] By adding an appropriate amount of silicon-based anti-drip agent, it can melt ahead of combustion, transfer through the pores of the polymer matrix to the polyester surface, and form a dense and stable silicon-containing glass layer. This not only prevents the further escape of flammable substances produced by combustion and decomposition, but also acts as a barrier to oxygen and heat, retarding further thermal decomposition of the polyester, thereby improving the polyester's anti-drip performance. However, if the amount of silicon-based anti-drip agent added is too large, the combustion process will produce an excessively thick condensed phase barrier layer, which will affect the heat-carrying flame retardant mechanism of the phosphorus-based flame retardant and cause a decrease in the flame retardant limiting oxygen index of the polyester. Therefore, it is necessary to add an appropriate amount.

[0013] Furthermore, the silicon-based anti-dripping agent is one or more of polysiloxane, octaphenylcyclotetrasiloxane and silicon dioxide.

[0014] Preferably, in the synthetic monomers of the flame retardant and anti-drip polyester, the molar ratio of acid to alcohol is 1:1.05-1.5.

[0015] In a second aspect, the present invention provides a method for preparing the flame retardant and anti-drip polyester, comprising the following steps: S1: Pre-esterifying 2-carboxyethylphenylphosphinoic acid and 2-(diphenylphosphinomethyl)succinic acid with ethylene glycol to obtain esterified liquid a and esterified liquid b respectively; S2: mixing terephthalic acid, ethylene glycol, esterification liquid a, esterification liquid b and a catalyst, and polymerizing to obtain a flame-retardant and anti-drip polyester.

[0016] After CEPPA and DPO-ITA are pre-esterified (step S1), they are then copolymerized with terephthalic acid and ethylene glycol, which can reduce the steric hindrance of CEPPA and DPO-ITA in the polymerization reaction, thereby increasing the grafting rate of the two flame retardants in the polyester. At the same time, the heat resistance of the two flame retardants after pre-esterification is significantly improved, which can reduce the occurrence of polymerization side reactions. Furthermore, compared to pre-esterifying CEPPA and DPO-ITA after mixing, the present invention adopts a method of pre-esterifying CEPPA and DPO-ITA separately, which can avoid the situation where the esterification rate is uneven due to the difference in the reactivity of the functional groups of the two flame retardants, and helps to ensure that the feed ratio is close to the grafting ratio.

[0017] Preferably, in step S1, the molar ratio of the 2-carboxyethylphenyl hypophosphorous acid to ethylene glycol is 1:2-8, and the molar ratio of the 2-(diphenylphosphorylmethyl)succinic acid to ethylene glycol is 1:2-8; the temperature of the pre-esterification reaction is 160-200°C, and the reaction is carried out until the water output reaches 90-95% of the theoretical water output.

[0018] Preferably, in step S2, the specific process of mixing terephthalic acid, ethylene glycol, esterification liquid a, esterification liquid b and the catalyst includes: stirring and mixing esterification liquid a and esterification liquid b at 80-100° C. for 1-2 hours, and then mixing with terephthalic acid, ethylene glycol and the catalyst.

[0019] Preferably, in step S2, the catalyst is an antimony-based catalyst; and the amount of the antimony-based catalyst added is 150-350 ppm of the theoretical polyester yield, calculated as antimony element.

[0020] Furthermore, the antimony-based catalyst is one or more of antimony glycol, antimony trioxide and antimony acetate.

[0021] Preferably, in step S2, the specific process of the polymerization includes: esterification at 0-0.2 MPa and 210-260° C. until the water output reaches 90-95% of the theoretical water output, pre-polycondensation at 50-1000 Pa and 250-280° C. for 30-70 min, and then final polycondensation at 20-200 Pa and 260-290° C. for 60-100 min.

[0022] Compared with the prior art, the present invention has the following advantages: (1) The present invention uses two specific phosphorus-based flame retardants (CEPPA and DPO-ITA) in combination, which can play a role in the initial combustion stage and the sustained combustion stage respectively, thereby enabling polyester to have both good flame retardancy and anti-dripping properties.

[0023] (2) The present invention can improve the anti-dripping performance of the flame retardant polyester while ensuring its flame retardant performance by adding a silicon-based anti-dripping agent and controlling its addition amount to 2500-10000ppm based on the mass of the flame retardant anti-dripping polyester. DETAILED DESCRIPTION

[0024] The present invention will be further described below with reference to the embodiments.

[0025] Overall embodiment The invention discloses a flame retardant anti-melting dripping polyester, which is prepared by copolymerizing synthetic monomers including terephthalic acid, ethylene glycol, 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid.

[0026] In some specific embodiments, the molar ratio of the 2-carboxyethylphenylphosphinate to the 2-(diphenylphosphorylmethyl)succinic acid is 1:0.3-3, calculated as phosphorus element.

[0027] In some specific embodiments, the total amount of the 2-carboxyethylphenylphosphinate and 2-(diphenylphosphorylmethyl)succinic acid is 5000-12000 ppm of the mass (theoretical yield) of the flame retardant and anti-drip polyester, calculated as elemental phosphorus.

[0028] In some specific embodiments, the flame-retardant anti-drip polyester further comprises a silicon-based anti-drip agent, wherein the amount of the silicon-based anti-drip agent is 2,500-10,000 ppm based on the mass (theoretical yield) of the flame-retardant anti-drip polyester, calculated as elemental silicon. Optionally or preferably, the silicon-based anti-drip agent is one or more of polysiloxane, octaphenylcyclotetrasiloxane, and silicon dioxide.

[0029] In some specific embodiments, in the synthetic monomers of the flame retardant and anti-drip polyester, the molar ratio of acid to alcohol is 1:1.05-1.5.

[0030] A method for preparing the flame-retardant and anti-drip polyester comprises the following steps: S1: Pre-esterifying 2-carboxyethylphenylphosphinoic acid and 2-(diphenylphosphinomethyl)succinic acid with ethylene glycol to obtain esterified liquid a and esterified liquid b respectively; S2: mixing terephthalic acid, ethylene glycol, esterification liquid a, esterification liquid b and a catalyst, and polymerizing to obtain a flame-retardant and anti-drip polyester.

[0031] In some specific embodiments, in step S1, the molar ratio of the 2-carboxyethylphenyl hypophosphorous acid to ethylene glycol is 1:2-8, and the molar ratio of the 2-(diphenylphosphorylmethyl)succinic acid to ethylene glycol is 1:2-8; the temperature of the pre-esterification reaction is 160-200°C, and the reaction is carried out until the water output reaches 90-95% of the theoretical water output.

[0032] In some specific embodiments, preferably, in step S2, the specific process of mixing terephthalic acid, ethylene glycol, esterification liquid a, esterification liquid b and the catalyst includes: stirring and mixing esterification liquid a and esterification liquid b at 80-100° C. for 1-2 hours, and then mixing with terephthalic acid, ethylene glycol and the catalyst.

[0033] In some specific embodiments, in step S2, the catalyst is an antimony-based catalyst; the amount of antimony-based catalyst added, calculated as antimony element, is 150-350 ppm based on the theoretical polyester yield. Optionally or preferably, the antimony-based catalyst is one or more of ethylene glycol antimony, antimony trioxide, and antimony acetate.

[0034] In some specific embodiments, in step S2, the specific process of the polymerization includes: esterification at 0-0.2 MPa and 210-260°C until the water output reaches 90-95% of the theoretical water output, pre-polycondensation at 50-1000 Pa and 250-280°C for 30-70 minutes, and then final polycondensation at 20-200 Pa and 260-290°C for 60-100 minutes. Specific embodiments The present invention is described below by way of specific examples. It should be understood that these examples are intended only to illustrate the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit and scope of the inventive concept, any changes and advantages that can be imagined by those skilled in the art are included in the present invention, and the scope of protection of the present invention is defined by the appended claims and any equivalents thereof.

[0036] Example 1 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 1:1 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0037] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 5000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0038] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0039] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0040] Example 2 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 3:1 based on elemental phosphorus), the stirring temperature was controlled at 85-95°C, and the stirring time was 2 hours to obtain a mixed flame retardant esterified liquid.

[0041] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 5000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0042] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0043] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0044] Example 3 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 1:3 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0045] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 5000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0046] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0047] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0048] Example 4 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 1:1 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0049] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, octaphenylcyclotetrasiloxane (calculated as silicon element, the amount of octaphenylcyclotetrasiloxane added is 5000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and a mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is performed, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0050] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0051] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0052] Example 5 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 1:1 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0053] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, silica (calculated as silicon element, the amount of silica added is 5000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0054] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0055] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0056] Example 6 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 1:1 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0057] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 2500ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0058] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0059] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0060] Example 7 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 1:1 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0061] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 10000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0062] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0063] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0064] Example 8 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 1:1 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0065] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 5000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 12000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out to discharge the air in the system, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0066] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0067] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0068] Comparative Example 1 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430 g of CEPPA powder and 1000 g of ethylene glycol were placed in a reactor and stirred. The atmosphere was replaced with nitrogen three times. The temperature was raised to 160° C. at a heating rate of 5° C. / min, and then to 190° C. at a heating rate of 0.5° C. / min. The reaction temperature was controlled at 185-195° C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid.

[0069] S2: Beating and esterification reaction 830 g of terephthalic acid, 288 g of ethylene glycol, 0.35 g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 5000 ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and CEPPA esterification liquid (calculated as phosphorus element, the amount of CEPPA esterification liquid added is 8000 ppm of the theoretical amount of flame retardant and anti-melting polyester produced) were added to a 2.5 L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement was performed, the air in the system was discharged, the pressure was increased to 0.2 MPa, and the esterification tower temperature was controlled at 230-240 ° C for the esterification reaction. When the water output reached 95% of the theoretical water output, the esterification reaction was terminated.

[0070] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0071] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0072] Comparative Example 2 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430 g of DPO-ITA powder and 1000 g of ethylene glycol were put into a reactor and stirred. The mixture was replaced with nitrogen three times. The temperature was raised to 160 ° C at a heating rate of 5 ° C / min, and then to 190 ° C at a heating rate of 0.5 ° C / min. The reaction temperature was controlled at 185-195 ° C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain DPO-ITA esterified liquid.

[0073] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 5000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and DPO-ITA esterification liquid (calculated as phosphorus element, the amount of DPO-ITA esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0074] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0075] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0076] Comparative Example 3 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 1:1 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0077] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 1000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0078] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0079] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0080] Comparative Example 4 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 1:1 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0081] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 15000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0082] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0083] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0084] Comparative Example 5 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor, stirred, and nitrogen purged three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of [(6-oxo-6H-dibenzo[C,E][1,2]oxaphosphorin-6-yl)methyl]succinic acid (DDP) powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DDP esterified liquid. The CEPPA esterification liquid and the DDP esterification liquid were mixed in a certain proportion (calculated on the basis of phosphorus element, the molar ratio between the CEPPA esterification liquid and the DDP esterification liquid was 1:1), the stirring temperature was controlled at 85-95° C., and the stirring time was 2 h to obtain a mixed flame retardant esterification liquid.

[0085] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 5000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0086] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0087] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0088] Comparative Example 6 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain ratio (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 7:1 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0089] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 5000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0090] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0091] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0092] Comparative Example 7 The flame-retardant, drip-resistant polyester was prepared and formed into chips, test strips, and fibers using the following steps: S1: Pre-esterification reaction 430g of CEPPA powder and 1000g of ethylene glycol were placed in a reactor and stirred. The atmosphere was purged with nitrogen three times. The temperature was raised to 160°C at a heating rate of 5°C / min, then to 190°C at a heating rate of 0.5°C / min. The reaction temperature was controlled at 185-195°C. When the water output reached 95% of the theoretical water output, the pre-esterification reaction was completed to obtain a CEPPA esterified liquid. 430g of DPO-ITA powder and 1000g of ethylene glycol were pre-esterified according to the same steps to obtain a DPO-ITA esterified liquid. The CEPPA esterified liquid and the DPO-ITA esterified liquid were mixed in a certain proportion (the molar ratio of CEPPA esterified liquid to DPO-ITA esterified liquid was 1:7 based on phosphorus element), the stirring temperature was controlled at 85-95°C, and the stirring time was 2h to obtain a mixed flame retardant esterified liquid.

[0093] S2: Beating and esterification reaction 830g of terephthalic acid, 288g of ethylene glycol, 0.35g of ethylene glycol antimony, polysiloxane (calculated as silicon element, the amount of polysiloxane added is 5000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) and mixed flame retardant esterification liquid (calculated as phosphorus element, the amount of mixed flame retardant esterification liquid added is 8000ppm of the theoretical amount of flame retardant and anti-melting polyester produced) are added to a 2.5L polymerization kettle and beaten for 10 minutes. After beating, nitrogen replacement is carried out, the air in the system is discharged, the pressure is increased to 0.2MPa, and the temperature of the esterification tower is controlled at 230-240°C for the esterification reaction. When the water output reaches 95% of the theoretical water output, the esterification reaction is terminated.

[0094] S3: Polycondensation and pelletizing After the esterification reaction in step S2 is completed, a pre-polycondensation reaction is carried out at 260°C and 200 Pa. After the reaction for 50 minutes, a final polycondensation reaction is carried out at 275°C and 50 Pa. The polycondensation reaction is terminated after the reaction for 80 minutes. After standing, the material is discharged and pelletized to obtain flame-retardant and anti-melt-drip polyester chips.

[0095] S4: Injection Molding and Spinning Flame-retardant, anti-drip polyester chips were placed in a vacuum drum dryer and dried at 120°C for 12 hours. The dried chips were then injected into a small injection molding machine to produce test strips at a temperature of 260°C. The dried chips were then spun using a small spinning machine at a temperature of 276°C and a yarn size of 167 dtex / 48f to produce flame-retardant, anti-drip polyester fibers.

[0096] Test Case The slices, test specimens and fibers prepared in each embodiment and comparative example were taken and performance tested according to the following method: (1) The intrinsic viscosity of chips was tested according to GB / T 14190-2017 “Test method for fiber-grade polyester (PET) chips”; (2) The vertical burning of the specimen adopts GB / T 2408-2021 "Determination of combustion properties of plastics - Horizontal and vertical methods"; (3) The limiting oxygen index of the fiber is tested using FZ / T 50017-2011 “Test method for flame retardancy of polyester fibers - Oxygen index method”.

[0097] The test results are shown in Table 1.

[0098] Table 1 Flame retardant and anti-melting droplet polyester performance test results According to the test results in Table 1, it can be seen that: (1) Compared with Comparative Example 1 and Comparative Example 6, the polyesters of Examples 1 to 3 produce fewer droplets during combustion; compared with Comparative Example 2 and Comparative Example 7, the polyesters of Examples 1 to 3 have a higher limiting oxygen index. The results show that compared with the use of CEPPA and DPO-ITA alone, the combination of the two in a certain ratio can better balance the flame retardancy and anti-dripping properties of polyester. The reason is that in the initial combustion stage, the phosphorus-containing groups introduced by CEPPA into the polyester preferentially decompose upon thermal decomposition, generating acid sources and phosphorus free radicals. The phosphoric acid source acts as a dehydrating agent to promote charring. While absorbing heat to prevent further combustion of the combustible gas, it also forms a protective carbon layer on the polyester surface, hindering oxygen diffusion and heat and mass transfer between the gas and solid phases. The phosphorus free radicals capture active free radicals in the combustion flame zone, slowing the combustion reaction and exerting a flame retardant effect in the condensed phase and gas phase first, thus achieving a flame retardant effect while maintaining the integrity of the main chain. In the subsequent sustained combustion stage, the phosphorus-containing groups introduced by DPO-ITA into the polyester decompose, also generating acid sources and free radicals. The acid source promotes charring to compensate for the insufficient thickness and area of the carbon layer in the first stage, strengthening the condensed phase barrier effect. The high content of free radicals reacts with a large amount of concentrated H· or HO·, preventing sustained combustion.

[0099] (2) It can be seen from Example 1, Example 6, Example 7, Comparative Example 3 and Comparative Example 4 that, within a certain range, by increasing the amount of silicon-based anti-drip agent added, the anti-drip performance of polyester can be improved, but when the amount added is too high, the flame retardant performance of polyester will decrease. The reason for this is that by adding an appropriate amount of silicon-based anti-drip agent, it can melt first during combustion, pass through the pores of the polymer matrix and transfer to the surface of the polyester, forming a dense and stable silicon-containing glass layer, which prevents the further overflow of the flammable substances produced by combustion and decomposition, and also plays a role in isolating oxygen and heat, flame retardant further thermal decomposition of polyester, thereby improving the anti-drip performance of polyester; but when the amount of silicon-based anti-drip agent added is too large, the flame retardant performance of polyester will decrease. The combustion process will produce an overly thick condensed phase barrier layer, which will affect the heat-carrying flame retardant mechanism of the phosphorus-based flame retardant, resulting in a decrease in the flame retardant limiting oxygen index of polyester.

[0100] (3) Compared with Comparative Example 5, the polyester of Example 1 has better flame retardancy and anti-melting dripping properties. The reason for this is that compared with DDP, the phenylphosphonic acid structure in DPO-ITA has higher heat resistance and hydrolysis resistance. During the copolymerization process into polyester, it can have better polymerization stability and a higher copolymerization grafting rate. At the same time, DPO-ITA and CEPPA have better compatibility. These properties of DPO-ITA enable the combination of DPO-ITA and CEPPA to give polyester better flame retardancy and anti-melting dripping properties.

[0101] Unless otherwise defined, all technical and scientific terms used herein have the same meanings as commonly understood by those skilled in the art to which this disclosure pertains. Unless otherwise specified, the raw materials and equipment used herein are conventional in the art and can be obtained from conventional commercial sources. The methods used herein are conventional in the art, unless otherwise specified.

[0102] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A flame retardant and anti-drip polyester, characterized in that: The flame-retardant anti-melting drop polyester is prepared by copolymerizing synthetic monomers including terephthalic acid, ethylene glycol, 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid.

2. The flame retardant and anti-drip polyester according to claim 1, characterized in that: Calculated on the basis of phosphorus element, the molar ratio of the 2-carboxyethylphenyl hypophosphorous acid to the 2-(diphenylphosphorylmethyl)succinic acid is 1:0.3-3.

3. The flame retardant anti-drip polyester according to claim 1 or 2, characterized in that: Calculated on the basis of phosphorus element, the total amount of the 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid is 5000-12000 ppm based on the mass of the flame retardant and anti-drip polyester.

4. The flame retardant and anti-drip polyester according to claim 1, characterized in that: The flame retardant anti-melting drip polyester further comprises a silicon-based anti-melting drip agent; the amount of the silicon-based anti-melting drip agent is 2500-10000 ppm based on the mass of the flame retardant anti-melting drip polyester, calculated as silicon element.

5. The flame retardant and anti-drip polyester according to claim 1, characterized in that: In the synthetic monomers of the flame retardant and anti-melting polyester, the molar ratio of acid to alcohol is 1:1.05-1.

5.

6. A method for preparing the flame retardant and anti-drip polyester according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1: Pre-esterifying 2-carboxyethylphenylphosphinoic acid and 2-(diphenylphosphinomethyl)succinic acid with ethylene glycol to obtain esterified liquid a and esterified liquid b respectively; S2: mixing terephthalic acid, ethylene glycol, esterification liquid a, esterification liquid b and a catalyst, and polymerizing to obtain a flame-retardant and anti-drip polyester.

7. The preparation method according to claim 6, characterized in that In step S1, the molar ratio of the 2-carboxyethylphenyl hypophosphorous acid to ethylene glycol is 1:2-8, and the molar ratio of the 2-(diphenylphosphorylmethyl)succinic acid to ethylene glycol is 1:2-8; the temperature of the pre-esterification reaction is 160-200°C, and the reaction is carried out until the water output reaches 90-95% of the theoretical water output.

8. The preparation method according to claim 6, characterized in that In step S2, the specific process of mixing terephthalic acid, ethylene glycol, esterification liquid a, esterification liquid b and catalyst includes: stirring and mixing esterification liquid a and esterification liquid b at 80-100° C. for 1-2 hours, and then mixing with terephthalic acid, ethylene glycol and catalyst.

9. The preparation method according to claim 6, characterized in that In step S2, the catalyst is an antimony-based catalyst; calculated as antimony element, the added amount of the antimony-based catalyst accounts for 150-350 ppm of the theoretical yield of polyester.

10. The preparation method according to claim 6 or 9, characterized in that: In step S2, the specific process of the polymerization includes: esterification at 0-0.2 MPa and 210-260° C. until the water output reaches 90-95% of the theoretical water output, pre-polycondensation at 50-1000 Pa and 250-280° C. for 30-70 minutes, and then final polycondensation at 20-200 Pa and 260-290° C. for 60-100 minutes.

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