Preparation method of low-temperature cationic dyeable flame-retardant polyester

Abstract

The invention relates to the technical field of polyester synthesis, and discloses a preparation method of low-temperature cationic dyeable flame-retardant polyester, which comprises the following steps: S1, carrying out pre-polycondensation reaction on a reactive phosphorus flame retardant and dihydric alcohol; s2, carrying out pre-esterification reaction on the sulfonic acid group-containing dibasic acid and dihydric alcohol; and S3, carrying out copolymerization on the product S1, the product S2, dibasic acid and dihydric alcohol to obtain the low-temperature cationic dyeable flame-retardant polyester. By adopting the preparation method disclosed by the invention, thermal decomposition or hydrolysis of the phosphorus-containing polymer in the dyeing process can be reduced, so that the polyester can keep relatively good flame retardant property after being dyed.

Description

Technical Field

[0001] The invention relates to the technical field of polyester synthesis, and in particular to a method for preparing low-temperature cationic dyeable flame-retardant polyester. Background Art

[0002] Polyester, due to its excellent mechanical properties, dimensional stability, heat resistance, and low-cost scalability, is widely used in clothing, home textiles, decoration, and industrial applications. It has become the synthetic fiber material with the largest production capacity, fastest growth, and widest application. However, due to its chemical structure and combustion characteristics, polyester has a low limiting oxygen index (LOI). The LOI of pure polyethylene terephthalate (PET) is only 20-22%, making it a flammable material. Therefore, improving the flame retardancy of polyester materials, especially PET fibers for interior decoration, is of great significance. In addition, due to the regular arrangement of polyester molecular chains and the lack of polar groups, conventional PET fibers are mainly dyed with disperse dyes. These dyeing processes require high temperatures and high pressures, resulting in low color fastness. The dyeing process also consumes excessive energy and generates large amounts of wastewater, which is not environmentally friendly. Therefore, to ensure safety and meet current environmental requirements, flame-retardant polyester dyeable with low-temperature cationic dyes has become a new demand.

[0003] Flame-retardant modification of polyester can be achieved through blending, copolymerization, and finishing. Copolymerization offers advantages such as more stable product quality, less added comonomer, lower manufacturing costs, and longer-lasting flame retardancy. Currently, phosphorus-based flame retardants are becoming the preferred flame retardant for polyester materials due to their high efficiency, low smoke levels, and non-toxicity. However, phosphorus-containing polymers are susceptible to hydrolysis, which can negatively impact the flame retardant properties of polyester during finishing processes (especially dyeing and finishing).

[0004] Patent CN103739832A discloses a method for manufacturing a cationic dyeable flame-retardant polyester resin. A phosphorus-based flame retardant ester solution and a sulfonate-containing dihydroxyethyl isophthalate solution are prepared separately by direct esterification. These are then added in a certain proportion during the PET polycondensation stage. Polyols are also added as auxiliary agents during the polycondensation stage to enhance the flame retardant effect and control the decrease in the melting point of the polyester. However, this method does not address the problem of the phosphorus-containing polymer being easily hydrolyzed during the dyeing process. Summary of the Invention

[0005] To address the technical problem of phosphorus-containing polymers in flame-retardant modified polyesters being susceptible to hydrolysis during the dyeing process, resulting in a significant decrease in the flame retardant properties of the polyester after dyeing, the present invention provides a method for preparing low-temperature, cationic-dyable, flame-retardant polyester. This method reduces the thermal decomposition or hydrolysis of the phosphorus-containing polymers during the dyeing process, allowing the polyester to maintain good flame retardant properties after dyeing.

[0006] The specific technical solutions of the present invention are: A method for preparing a low-temperature cationic dyeable flame-retardant polyester comprises the following steps: S1: Pre-condensing the reactive phosphorus flame retardant with diol; S2: pre-esterifying the dibasic acid containing sulfonic acid group with diol; S3: copolymerizing the product of S1, the product of S2, a dibasic acid and a diol to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0007] In the present invention, the reactive phosphorus-based flame retardant is first subjected to a pre-condensation reaction with a diol to form an oligomer, which is then introduced into the polyester during polymerization. Compared to directly copolymerizing the reactive phosphorus-based flame retardant with a diol and a dibasic acid to form polyester, or esterifying the reactive phosphorus-based flame retardant with a diol before introducing it into the polyester during polymerization, the pre-formation of the oligomer in the present invention achieves higher thermal stability and reduces the degradation of the polyester's flame retardancy due to thermal decomposition or hydrolysis of the phosphorus-containing polymer during the subsequent dyeing process.

[0008] Furthermore, dibasic acids containing sulfonic acid groups possess ionic aggregation capabilities, which can crosslink and entangle polyester molecular chains, restricting their movement. This increases the apparent viscosity and strength of the melt, preventing droplets from dripping and providing more time for the melt to decompose into char. Therefore, they exhibit a certain anti-drip effect without affecting the flame retardant function. Furthermore, the negatively charged sulfonic acid groups can undergo ion exchange with cationic dyes, allowing the dye to bind to the dyeing site through chemical ionic bonds, resulting in high color fastness and high dye exhaustion rates. Therefore, the introduction of dibasic acids containing sulfonic acid groups can also improve the dyeing properties of flame-retardant polyester fibers.

[0009] Preferably, in step S1, the temperature of the pre-polycondensation reaction is 140 to 220° C., the pressure is -100 to -10 kPa, and the degree of polymerization of the pre-polycondensation reaction product is 3 to 7.

[0010] By controlling the degree of polymerization of the pre-polycondensation reaction product within the range of 3 to 7, the stability of the flame retardant properties of the polyester can be effectively improved, and the reduction in the flame retardant properties after dyeing can be minimized.

[0011] Preferably, in step S2, after the pre-esterification reaction is completed, a dispersant is added; the dispersant contains a hydrophilic group and a hydrophobic group, and the added amount is 0.04 to 0.5 mol% of the dibasic acid containing a sulfonic acid group.

[0012] Copolyesters obtained after modification with dibasic acids containing sulfonic acid groups are prone to agglomeration, resulting in a rapid increase in filtration pressure during melt spinning, making stable production difficult. To address this issue, the present invention pre-esterifies the dibasic acid containing sulfonic acid groups, adds a dispersant, and then copolymerizes the polyester. The hydrophilic and hydrophobic groups contained in the dispersant enable good compatibility with both the dibasic acid containing sulfonic acid groups and the polyester, facilitating good dispersion of the dibasic acid containing sulfonic acid groups in the polyester molecular chain. This reduces the ion aggregation effect between the sulfonic acid groups and avoids excessive increases in filtration pressure during the spinning process, which can affect stable production.

[0013] Furthermore, the dispersant includes sodium dodecylbenzenesulfonate and / or naphthalenesulfonic acid formaldehyde polymer.

[0014] Preferably, in step S1, the reactive phosphorus-based flame retardant comprises 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid in a molar ratio of 1:0.3 to 3; in step S1, 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid are respectively subjected to a pre-condensation reaction with a diol.

[0015] The structural formula of "2-(diphenylphosphorylmethyl)succinic acid" described in the present invention is as follows:

[0016] 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·, preventing sustained combustion. Through the above methods, the present invention uses a certain ratio of CEPPA and DPO-ITA to cooperate with each other to give polyester better flame retardant and anti-melting properties.

[0017] 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.

[0018] Preferably, in step S1, the molar ratio of the reactive phosphorus-based flame retardant to the diol in S1 is 1:2-8, and the added amount of the reactive phosphorus-based flame retardant calculated as phosphorus element is 5000-10000 ppm of the theoretical output of the low-temperature cationic dyeable flame-retardant polyester.

[0019] Preferably, in step S1, an alkaline compound is added during the pre-polycondensation reaction, and the amount added is 0.1 to 1 wt% of the diol in S1; in step S2, an alkaline compound is added during the pre-esterification reaction, and the amount added is 0.1 to 1 wt% of the diol in S2.

[0020] By adding a basic compound during the pre-polycondensation reaction and the pre-esterification reaction, the generation of diethylene glycol during the reaction can be suppressed.

[0021] Furthermore, the alkaline compound includes one or more of potassium acetate, sodium acetate, potassium hydroxide and sodium hydroxide.

[0022] Preferably, in step S2, the temperature of the pre-esterification reaction is 140-200°C, the pressure is 10-80 kPa, and the reaction time is 2-4 h; the molar ratio of the dibasic acid containing sulfonic acid groups to the diol in S2 is 1:2-8, and the added amount of the dibasic acid containing sulfonic acid groups accounts for 1-3 mol% of the total added amount of the dibasic acid containing sulfonic acid groups and the dibasic acid.

[0023] Preferably, the specific process of step S3 includes: mixing the S1 product, dibasic acid, diol and catalyst, performing esterification reaction, and then adding the S2 product to perform polycondensation reaction to obtain low-temperature cationic dyeable flame-retardant polyester.

[0024] Furthermore, in step S3, when adding the product of S2, polyether is also added, and the amount of polyether added is 0.5-5.0 wt% of the theoretical output of the low-temperature cationic dyeable flame-retardant polyester.

[0025] The addition of polyether can destroy the regularity of the polyester molecular chain and increase the distance between macromolecules, reduce the intermolecular force, increase the amorphous region in the molecular chain, and reduce the glass transition temperature, so that the dye can enter the polyester molecular chain and combine with the dyeing site at a lower temperature, thereby reducing the dyeing temperature and helping to reduce the loss of flame retardant properties caused by thermal decomposition or hydrolysis of phosphorus-containing polymers during the dyeing process to a greater extent.

[0026] Furthermore, the polyether includes one or more of polyethylene glycol, polypropylene glycol and polybutylene glycol.

[0027] Furthermore, the polyether is polyethylene glycol with a number average molecular weight of 400 to 10,000 Da.

[0028] Furthermore, in step S3, the catalyst is an antimony catalyst and / or a titanium catalyst; the temperature of the esterification reaction is 240-250°C, the pressure is 250-350 kPa, and the time is 2-3 hours; the temperature of the polycondensation reaction is 275-280°C, the pressure is -100--80 kPa, and the time is 2-3 hours.

[0029] Preferably, in step S2, the dibasic acid containing a sulfonic acid group includes one or more of dimethyl isophthalate-5-sodium sulfonate, dimethyl isophthalate-5-lithium sulfonate, dimethyl isophthalate-5-potassium sulfonate, sodium isophthalate-5-sodium sulfonate, lithium isophthalate-5-sodium sulfonate and potassium isophthalate-5-sodium sulfonate.

[0030] Preferably, in step S3, the molar ratio of the dibasic acid to the diol is 1:1.1-2.

[0031] Preferably, in steps S1 to S3, the diol includes one or more of ethylene glycol, propylene glycol and butanediol; in step S3, the dibasic acid includes one or more of terephthalic acid, isophthalic acid and phthalic acid.

[0032] Compared with the prior art, the present invention has the following advantages: (1) The present invention reduces the thermal decomposition or hydrolysis of the phosphorus-containing polymer during the dyeing process by pre-condensing the reactive phosphorus-based flame retardant with the diol to form an oligomer with a certain degree of polymerization, and then participates in the copolymerization synthesis of the polyester, so that the polyester can maintain good flame retardant properties after dyeing.

[0033] (2) The present invention pre-esterifies the dibasic acid containing sulfonic acid groups, adds a dispersant containing a hydrophilic group and a hydrophobic group, and then participates in the copolymerization synthesis of polyester, which can reduce the ion aggregation effect between the sulfonic acid groups, thereby avoiding excessive increase in filter pressure during the spinning process and affecting stable production.

[0034] (3) The present invention adopts a compound of 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid in a molar ratio of 1:0.3 to 3 as a reactive phosphorus-based flame retardant. The latter can be used to decompose in the initial stage of combustion to produce a flame retardant effect while maintaining the integrity of the main chain, and the former can be used to decompose in the subsequent continuous combustion stage to prevent continuous combustion, thereby giving polyester better flame retardancy and anti-dripping properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 This is a photo of the polyester strip in Example 1 after burning.

[0036] Figure 2 These are photos of the polyester fabrics of Example 1 and Comparative Example 1 after dyeing at 80°C. DETAILED DESCRIPTION

[0037] The present invention will be further described below with reference to the embodiments.

[0038] Overall embodiment A method for preparing a low-temperature cationic dyeable flame-retardant polyester comprises the following steps: S1: Pre-condensing the reactive phosphorus flame retardant with diol; S2: pre-esterifying the dibasic acid containing sulfonic acid group with diol; S3: copolymerizing the product of S1, the product of S2, a dibasic acid and a diol to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0039] In some specific embodiments, in step S1, the temperature of the pre-polycondensation reaction is 140 to 220° C., the pressure is -100 to -10 kPa, and the degree of polymerization of the pre-polycondensation reaction product is 3 to 7.

[0040] In some specific embodiments, in step S1, the reactive phosphorus-based flame retardant comprises 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid in a molar ratio of 1:0.3 to 3; in step S1, 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid are respectively subjected to a pre-condensation reaction with a diol.

[0041] In some specific embodiments, in step S1, the molar ratio of the reactive phosphorus-based flame retardant to the diol in S1 is 1:2-8, and the added amount of the reactive phosphorus-based flame retardant calculated as phosphorus element is 5000-10000 ppm of the theoretical output of the low-temperature cationic dyeable flame-retardant polyester.

[0042] In some specific embodiments, in step S1, an alkaline compound is added during the pre-polycondensation reaction in an amount of 0.1 to 1 wt% of the diol in S1; and in step S2, an alkaline compound is added during the pre-esterification reaction in an amount of 0.1 to 1 wt% of the diol in S2. The alkaline compound can be selected from one or more of potassium acetate, sodium acetate, potassium hydroxide, and sodium hydroxide.

[0043] In some specific embodiments, in step S2, the temperature of the pre-esterification reaction is 140-200° C., the pressure is 10-80 kPa, and the reaction time is 2-4 h.

[0044] In some specific embodiments, in step S2, the dibasic acid containing a sulfonic acid group includes one or more of dimethyl isophthalate-5-sodium sulfonate, dimethyl isophthalate-5-lithium sulfonate, dimethyl isophthalate-5-potassium sulfonate, isophthalic acid-5-sodium sulfonate, isophthalic acid-5-lithium sulfonate, isophthalic acid-5-potassium sulfonate, isophthalic acid-5-sodium sulfonate, isophthalic acid-5-lithium sulfonate, and isophthalic acid-5-potassium sulfonate.

[0045] In some specific embodiments, in step S2, the molar ratio of the dibasic acid containing sulfonic acid groups to the diol in S2 is 1:2-8, and the added amount of the dibasic acid containing sulfonic acid groups accounts for 1-3 mol% of the total added amount of the dibasic acid containing sulfonic acid groups and dibasic acid.

[0046] In some embodiments, in step S2, after the pre-esterification reaction is completed, a dispersant is added; the dispersant contains a hydrophilic group and a hydrophobic group, and the amount added is 0.04-0.5 mol% of the dibasic acid containing a sulfonic acid group. The dispersant can be selected from sodium dodecylbenzenesulfonate and / or naphthalenesulfonic acid formaldehyde polymer.

[0047] In some specific embodiments, the specific process of step S3 includes: mixing the product of S1, a dibasic acid, a diol, and a catalyst, performing an esterification reaction, and then adding the product of S2 and a polyether to perform a polycondensation reaction to obtain a low-temperature cationic dyeable flame-retardant polyester. Optionally or preferably, the polyether includes one or more of polyethylene glycol, polypropylene glycol, and polybutylene glycol, and the amount added is 0.5 to 5.0 wt% of the theoretical yield of the low-temperature cationic dyeable flame-retardant polyester; the catalyst is an antimony catalyst and / or a titanium catalyst; the esterification reaction is carried out at a temperature of 240 to 250°C, a pressure of 250 to 350 kPa, and a time of 2 to 3 hours; and the polycondensation reaction is carried out at a temperature of 275 to 280°C, a pressure of -100 to -80 kPa, and a time of 2 to 3 hours.

[0048] In some specific embodiments, in step S3, the molar ratio of the dibasic acid to the diol is 1:1.1-2.

[0049] In some specific embodiments, in steps S1 to S3, the diol includes one or more of ethylene glycol, propylene glycol, and butanediol; in step S3, the dibasic acid includes one or more of terephthalic acid, isophthalic acid, and phthalic acid. 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.

[0051] In the following examples and comparative examples, the meanings of the abbreviations are as follows: CEPPA: 2-carboxyethylphenylphosphinate; DPO-ITA: 2-(diphenylphosphorylmethyl)succinic acid; DDP: [(6-oxo-6H-dibenzo[C,E][1,2]oxaphosphorin-6-yl)methyl]butanedioic acid; PEG2000: polyethylene glycol with a number average molecular weight of 2000 Da.

[0052] Example 1 The preparation method of low-temperature cationic dyeable flame-retardant polyester is prepared by the following steps: S1: Preparation of flame retardant oligomers 400 g of flame retardant CEPPA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 180° C. and a pre-polycondensation reaction was carried out at -80 kPa to form an oligomer with a polymerization degree of 3. The material was discharged to obtain a flame retardant oligomer.

[0053] S2: Preparation of 5-sodium sulfonate isophthalic acid ester solution: 540 g of 5-sodium sulfonate isophthalic acid, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 160°C and a pre-esterification reaction was carried out at 10 kPa for 2 hours. Then, 0.35 g of sodium dodecylbenzenesulfonate was added to the reactor and stirring was continued for 30 minutes to obtain a 5-sodium sulfonate isophthalic acid ester solution.

[0054] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate ester solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0055] Example 2 The preparation method of low-temperature cationic dyeable flame-retardant polyester is prepared by the following steps: S1: Preparation of flame retardant oligomers 400 g of flame retardant CEPPA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 180° C. and a pre-polycondensation reaction was carried out at -80 kPa to form an oligomer with a degree of polymerization of 7. The material was discharged to obtain a flame retardant oligomer.

[0056] S2: Preparation of 5-sodium sulfonate isophthalic acid ester solution: 540 g of 5-sodium sulfonate isophthalic acid, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 160°C and a pre-esterification reaction was carried out at 10 kPa for 2 hours. Then, 0.35 g of sodium dodecylbenzenesulfonate was added to the reactor and stirring was continued for 30 minutes to obtain a 5-sodium sulfonate isophthalic acid ester solution.

[0057] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 9000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 9000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate ester solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0058] Example 3 The only difference between this embodiment and embodiment 1 is that the flame retardant CEPPA used in the low-temperature cationic dyeable flame-retardant polyester is replaced with DPO-ITA. In this embodiment, the specific steps for preparing the low-temperature cationic dyeable flame-retardant polyester are as follows: S1: Preparation of flame retardant oligomers Weigh 540 g of flame retardant DPO-ITA, 496 g of ethylene glycol and 2.5 g of sodium acetate into a reactor, stir for 10 minutes, then heat to 180°C and carry out a pre-polycondensation reaction at -80 kPa to form an oligomer with a degree of polymerization of 3. Discharge the material to obtain a flame retardant oligomer.

[0059] S2: Preparation of 5-sodium sulfonate isophthalic acid ester solution: 540 g of 5-sodium sulfonate isophthalic acid, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 160°C and a pre-esterification reaction was carried out at 10 kPa for 2 hours. Then, 0.35 g of sodium dodecylbenzenesulfonate was added to the reactor and stirring was continued for 30 minutes to obtain a 5-sodium sulfonate isophthalic acid ester solution.

[0060] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate ester solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0061] Example 4 The only difference between this example and Example 1 is that the flame retardant CEPPA used in the low-temperature cationic dyeable flame-retardant polyester is replaced with CEPPA and DPO-ITA in a molar ratio of 1:3. In this example, the specific steps for preparing the low-temperature cationic dyeable flame-retardant polyester are as follows: S1: Preparation of flame retardant oligomers 400 g of flame retardant CEPPA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 180° C. and a pre-polycondensation reaction was carried out at -80 kPa to form an oligomer with a degree of polymerization of 3. The material was discharged to obtain a CEPPA flame retardant oligomer.

[0062] Weigh 540 g of flame retardant DPO-ITA, 496 g of ethylene glycol and 2.5 g of sodium acetate into a reactor, stir for 10 minutes, then heat to 180°C, and carry out a pre-polycondensation reaction at -80 kPa to form an oligomer with a degree of polymerization of 3. Discharge the material to obtain a DPO-ITA flame retardant oligomer.

[0063] The CEPPA flame retardant oligomer and the DPO-ITA flame retardant oligomer were mixed according to a molar ratio of CEPPA to DPO-ITA of 1:3 to obtain a flame retardant oligomer.

[0064] S2: Preparation of 5-sodium sulfoisophthalate solution 540 g of 5-sodium sulfoisophthalic acid, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 160° C. and a pre-esterification reaction was carried out at 10 kPa for 2 hours. Then, 0.35 g of sodium dodecylbenzenesulfonate was added to the reactor and stirring was continued for 30 minutes to obtain a sodium 5-sulfoisophthalic acid ester solution.

[0065] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate ester solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0066] Example 5 The only difference between this example and Example 1 is that the flame retardant CEPPA used in the low-temperature cationic dyeable flame-retardant polyester is replaced with CEPPA and DPO-ITA in a molar ratio of 3:1. In this example, the specific steps for preparing the low-temperature cationic dyeable flame-retardant polyester are as follows: S1: Preparation of flame retardant oligomers 400 g of flame retardant CEPPA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 180° C. and a pre-polycondensation reaction was carried out at -80 kPa to form an oligomer with a degree of polymerization of 3. The material was discharged to obtain a CEPPA flame retardant oligomer.

[0067] Weigh 540 g of flame retardant DPO-ITA, 496 g of ethylene glycol and 2.5 g of sodium acetate into a reactor, stir for 10 minutes, then heat to 180°C, and carry out a pre-polycondensation reaction at -80 kPa to form an oligomer with a degree of polymerization of 3. Discharge the material to obtain a DPO-ITA flame retardant oligomer.

[0068] The CEPPA flame retardant oligomer and the DPO-ITA flame retardant oligomer were mixed according to a molar ratio of CEPPA to DPO-ITA of 3:1 to obtain a flame retardant oligomer.

[0069] S2: Preparation of 5-sodium sulfoisophthalate solution 540 g of 5-sodium sulfoisophthalic acid, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 160° C. and a pre-esterification reaction was carried out at 10 kPa for 2 hours. Then, 0.35 g of sodium dodecylbenzenesulfonate was added to the reactor and stirring was continued for 30 minutes to obtain a sodium 5-sulfoisophthalic acid ester solution.

[0070] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate ester solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0071] Example 6 The only difference between this example and Example 1 is that the flame retardant CEPPA used in the low-temperature cationic dyeable flame-retardant polyester is replaced with CEPPA and DPO-ITA in a molar ratio of 1:6. In this example, the specific steps for preparing the low-temperature cationic dyeable flame-retardant polyester are as follows: S1: Preparation of flame retardant oligomers 400 g of flame retardant CEPPA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 180° C. and a pre-polycondensation reaction was carried out at -80 kPa to form an oligomer with a degree of polymerization of 3. The material was discharged to obtain a CEPPA flame retardant oligomer.

[0072] Weigh 540 g of flame retardant DPO-ITA, 496 g of ethylene glycol and 2.5 g of sodium acetate into a reactor, stir for 10 minutes, then heat to 180°C, and carry out a pre-polycondensation reaction at -80 kPa to form an oligomer with a degree of polymerization of 3. Discharge the material to obtain a DPO-ITA flame retardant oligomer.

[0073] The CEPPA flame retardant oligomer and the DPO-ITA flame retardant oligomer were mixed according to a molar ratio of CEPPA to DPO-ITA of 1:6 to obtain a flame retardant oligomer.

[0074] S2: Preparation of 5-sodium sulfoisophthalate solution 540 g of 5-sodium sulfoisophthalic acid, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 160° C. and a pre-esterification reaction was carried out at 10 kPa for 2 hours. Then, 0.35 g of sodium dodecylbenzenesulfonate was added to the reactor and stirring was continued for 30 minutes to obtain a sodium 5-sulfoisophthalic acid ester solution.

[0075] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate ester solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0076] Example 7 The only difference between this example and Example 1 is that the flame retardant CEPPA used in the low-temperature cationic dyeable flame-retardant polyester is replaced with CEPPA and DPO-ITA in a molar ratio of 6:1. In this example, the specific steps for preparing the low-temperature cationic dyeable flame-retardant polyester are as follows: S1: Preparation of flame retardant oligomers 400 g of flame retardant CEPPA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 180° C. and a pre-polycondensation reaction was carried out at -80 kPa to form an oligomer with a degree of polymerization of 3. The material was discharged to obtain a CEPPA flame retardant oligomer.

[0077] 540 g of flame retardant DPO-ITA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 180° C. and a pre-polycondensation reaction was carried out at -80 kPa to form an oligomer with a degree of polymerization of 3. The material was discharged to obtain a DPO-ITA flame retardant oligomer.

[0078] The CEPPA flame retardant oligomer and the DPO-ITA flame retardant oligomer were mixed according to a molar ratio of CEPPA to DPO-ITA of 6:1 to obtain a flame retardant oligomer.

[0079] S2: Preparation of 5-sodium sulfoisophthalate solution 540 g of 5-sodium sulfoisophthalic acid, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 160° C. and a pre-esterification reaction was carried out at 10 kPa for 2 hours. Then, 0.35 g of sodium dodecylbenzenesulfonate was added to the reactor and stirring was continued for 30 minutes to obtain a sodium 5-sulfoisophthalic acid ester solution.

[0080] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate ester solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0081] Example 8 This Example differs from Example 1 only in that the flame retardant CEPPA used in the low-temperature cationic dyeable flame-retardant polyester is replaced with CEPPA and DDP in a molar ratio of 1:3. In this Example, the specific steps for preparing the low-temperature cationic dyeable flame-retardant polyester are as follows: S1: Preparation of Flame Retardant Oligomer: 400 g of the flame retardant CEPPA, 496 g of ethylene glycol, and 2.5 g of sodium acetate are weighed and placed in a reactor. After stirring for 10 minutes, the temperature is raised to 180°C and a pre-polycondensation reaction is carried out at -80 kPa to form an oligomer with a degree of polymerization of 3. The product is discharged to obtain a CEPPA flame retardant oligomer.

[0082] 540 g of flame retardant DDP, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 180° C. and a pre-polycondensation reaction was carried out at -80 kPa to form an oligomer with a polymerization degree of 3. The material was discharged to obtain a DDP flame retardant oligomer.

[0083] According to the molar ratio of CEPPA to DDP being 1:3, CEPPA flame retardant oligomer and DDP flame retardant oligomer were mixed to obtain flame retardant oligomer.

[0084] S2: Preparation of 5-sodium sulfoisophthalate solution 540 g of 5-sodium sulfoisophthalic acid, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 160° C. and a pre-esterification reaction was carried out at 10 kPa for 2 hours. Then, 0.35 g of sodium dodecylbenzenesulfonate was added to the reactor and stirring was continued for 30 minutes to obtain a sodium 5-sulfoisophthalic acid ester solution.

[0085] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate ester solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0086] Comparative Example 1 The only difference between this comparative example and Example 1 is that in step S1, the pre-polycondensation reaction is replaced with a pre-esterification reaction; in step S2, the dispersant sodium dodecylbenzenesulfonate is not added; and in step S3, PEG2000 is not added. In this comparative example, the specific steps for preparing the cationic dyeable flame-retardant polyester are as follows: S1: Preparation of flame retardant esters 400 g of flame retardant CEPPA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 175° C. and a pre-esterification reaction was carried out at 10 kPa for 2 hours before discharging to obtain a flame retardant ester.

[0087] S2: Preparation of 5-sodium sulfoisophthalate solution 540 g of 5-sodium sulfoisophthalate, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 min, the temperature was raised to 160° C. and a pre-esterification reaction was carried out at 10 kPa for 2 h to obtain a sodium sulfoisophthalate ester solution.

[0088] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant ester (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were put into a reactor, stirred for 10 minutes, and esterified at 300 kPa and 245 ° C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalic acid ester solution was added to the reactor, and then a condensation reaction was carried out at -100 kPa and 280 ° C for 2.5 hours to obtain a cationic dyeable flame retardant polyester.

[0089] Comparative Example 2 The only difference between this comparative example and Example 1 is that in step S1, the pre-polycondensation reaction is replaced by a pre-esterification reaction. In this comparative example, the specific steps for preparing the low-temperature cationic dyeable flame-retardant polyester are as follows: S1: Preparation of flame retardant oligomers 400 g of flame retardant CEPPA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 175° C. and a pre-esterification reaction was carried out at 10 kPa for 2 hours before discharging to obtain a flame retardant ester.

[0090] S2: Preparation of 5-sodium sulfoisophthalate solution 540 g of 5-sodium sulfoisophthalic acid, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 min, the temperature was raised to 160° C. and esterified at 10 kPa for 2 h. Then, 0.35 g of sodium dodecylbenzenesulfonate was added to the reactor and stirring was continued for 30 min to obtain a sodium 5-sulfoisophthalic acid ester solution.

[0091] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate ester solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a low-temperature cationic dyeable flame-retardant polyester.

[0092] Comparative Example 3 The only difference between this comparative example and Example 1 is that in step S2, no dispersant sodium dodecylbenzenesulfonate is added. In this comparative example, the specific steps for preparing the cationic dyeable flame-retardant polyester are as follows: S1: Preparation of flame retardant oligomers 400 g of flame retardant CEPPA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 180° C. and a pre-polycondensation reaction was carried out at -80 kPa to form an oligomer with a polymerization degree of 3. The material was discharged to obtain a flame retardant oligomer.

[0093] S2: Preparation of 5-sodium sulfonyl isophthalate ester solution: 540 g of 5-sodium sulfonyl isophthalate, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 min, the temperature was raised to 160° C. and a pre-esterification reaction was carried out at 10 kPa for 2 h to obtain 5-sodium sulfonyl isophthalate ester solution.

[0094] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a cationic dyeable flame-retardant polyester.

[0095] Comparative Example 4 The only difference between this comparative example and Example 1 is that PEG2000 is not added in step S3. In this comparative example, the specific steps for preparing the cationic dyeable flame-retardant polyester are as follows: S1: Preparation of flame retardant oligomers 400 g of flame retardant CEPPA, 496 g of ethylene glycol and 2.5 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 180° C. and a pre-polycondensation reaction was carried out at -80 kPa to form an oligomer with a polymerization degree of 3. The material was discharged to obtain a flame retardant oligomer.

[0096] S2: Preparation of 5-sodium sulfonate isophthalic acid ester solution: 540 g of 5-sodium sulfonate isophthalic acid, 744 g of ethylene glycol and 6 g of sodium acetate were weighed and put into a reactor. After stirring for 10 minutes, the temperature was raised to 160°C and a pre-esterification reaction was carried out at 10 kPa for 2 hours. Then, 0.35 g of sodium dodecylbenzenesulfonate was added to the reactor and stirring was continued for 30 minutes to obtain a 5-sodium sulfonate isophthalic acid ester solution.

[0097] S3: Preparation of low-temperature cationic dyeable flame-retardant polyester 830 g of terephthalic acid, 387 g of ethylene glycol, 7000 ppm of flame retardant oligomer (calculated as phosphorus element, the amount of flame retardant oligomer is 7000 ppm of the theoretical yield of polyester) and 0.35 g of ethylene glycol antimony were weighed and put into a reactor. After stirring for 10 minutes, the mixture was esterified at 300 kPa and 245°C for 2.5 hours. Then, 65 g of sodium 5-sulfonate isophthalate solution and 25 g of PEG2000 were added to the reactor. The mixture was then polycondensed at -100 kPa and 280°C for 2.5 hours to obtain a cationic dyeable flame-retardant polyester.

[0098] Test Example: After polyester was produced according to the methods of each embodiment and comparative example, it was pelletized. A portion of the obtained slices was injection molded into polyester strips, and another portion of the slices was spun into fibers with a specification of 135 dtex / 48 f. The obtained fibers were then spun and woven to produce polyester fabric. During the spinning process, the filter pressure difference was tested, and the results are shown in Table 2. The strength of the polyester fiber was also tested, and the results are shown in Table 2. The polyester strips of Example 1 were burned, and obvious charring was observed (e.g., Figure 1 shown).

[0099] The polyester fabric was dyed with cationic dyes. The dye bath was prepared as follows: the dye was methylene blue at a concentration of 2 mg / mL and the bath ratio was 1:100. The dye saturation values ​​at 80°C and 120°C were measured, and the results are shown in Table 2. The appearance of the polyester fabrics of Example 1 and Comparative Example 1 after dyeing at 80°C is shown in Table 2. Figure 2 As shown, the dyeing depth of the polyester fabric of Example 1 is significantly higher than that of Comparative Example 1. Before and after dyeing, the phosphorus content, limiting oxygen index (LOI) and number of droplets during vertical combustion of the polyester fabric were tested, and the results are shown in Table 1.

[0100] Table 1 Test results of flame retardant and anti-melting properties of polyester fabrics before and after dyeing Table 2 Test results of polyester spinning properties, mechanical properties and dyeing properties Analyzing the performance test results in Table 1 and Table 2, we can see that: (1) Compared with Comparative Example 2, the flame retardant and anti-melting properties of the polyester fabric of Example 1 decreased less after dyeing. The reason for this is that, compared with the method of Comparative Example 2 in which the reactive phosphorus-based flame retardant was esterified with diol and then introduced into the polyester polymerization process, Example 1 first pre-condensed the reactive phosphorus-based flame retardant with diol to form oligomers and then introduced them into the polyester polymerization process, which can achieve higher thermal stability and reduce the reduction in polyester flame retardancy due to thermal decomposition or hydrolysis of the phosphorus-containing polymer during the subsequent dyeing process.

[0101] (2) Compared with Comparative Example 3, the polyester of Example 1 has a smaller filter pressure difference during spinning. The reason for this is that in Example 1, a dispersant (sodium dodecylbenzenesulfonate) is added to the sodium 5-sulfoisophthalic acid ester solution. The dispersant has good compatibility with both the dibasic acid containing sulfonic acid groups and the polyester, which is conducive to the good dispersion of the dibasic acid containing sulfonic acid groups in the polyester molecular chain, thereby reducing the ion aggregation effect between the sulfonic acid groups and avoiding excessive increase in filter pressure during the spinning process, which affects stable production.

[0102] (3) Compared with Comparative Example 4, the polyester fabric of Example 1 has a higher dyeing saturation value when dyed at 80°C, indicating that the cationic dye dyeing temperature of polyester fabric can be effectively reduced by introducing polyether segments into the polyester molecular chain.

[0103] (4) Compared with Example 1 and Example 7, the polyester fabrics of Example 4 and Example 5 have better anti-melting droplet performance; compared with Example 3 and Example 6, the polyester fabrics of Example 4 and Example 5 have better flame retardant performance. The reason is that: in the initial combustion stage, the phosphorus-containing groups introduced by DPO-ITA in the polyester are preferentially decomposed by heat to produce acid sources and phosphorus free radicals. Among them, the phosphoric acid source acts as a dehydrating agent to promote carbonization. While absorbing heat to prevent the further combustion of the combustible gas, it can form a protective carbon layer on the polyester surface, hindering oxygen diffusion and heat and mass transfer between the gas phase and the solid phase. The phosphorus free radicals capture the active free radicals in the combustion flame area, slowing down the combustion reaction, and exerting a flame retardant effect in the condensed phase and gas phase first, producing a flame retardant effect while maintaining the integrity of the main chain; in the subsequent continuous combustion stage, the phosphorus-containing groups introduced by CEPPA in the polyester decompose, also producing 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, strengthen the barrier effect of the condensed phase, and the high content of free radicals reacts with a large amount of concentrated H· or HO· to ​​prevent continuous combustion. Therefore, the use of a certain proportion of CEPPA and DPO-ITA in combination can make polyester have good flame retardant and anti-dripping properties.

[0104] (5) Compared with Example 8, the polyester fabric of Example 4 has better flame retardant 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 good compatibility. These properties of DPO-ITA enable the combination of DPO-ITA + CEPPA to give polyester better flame retardant and anti-melting dripping properties.

[0105] 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.

[0106] 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 method for preparing a low-temperature cationic dyeable flame-retardant polyester, characterized in that: The following steps are involved: S1: Pre-condensing the reactive phosphorus flame retardant with diol; S2: pre-esterifying the dibasic acid containing sulfonic acid group with diol; S3: copolymerizing the product of S1, the product of S2, a dibasic acid and a diol to obtain a low-temperature cationic dyeable flame-retardant polyester.

2. The preparation method according to claim 1, characterized in that In step S1, the temperature of the pre-polycondensation reaction is 140-220° C., the pressure is -100--10 kPa, and the polymerization degree of the pre-polycondensation reaction product is 3-7.

3. The preparation method according to claim 1, characterized in that In step S2, after the pre-esterification reaction is completed, a dispersant is added; the dispersant contains a hydrophilic group and a hydrophobic group, and the added amount is 0.04-0.5 mol% of the dibasic acid containing a sulfonic acid group.

4. The preparation method according to claim 1, characterized in that In step S1, the reactive phosphorus-based flame retardant includes 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid in a molar ratio of 1:0.3~3; in step S1, 2-carboxyethylphenyl hypophosphorous acid and 2-(diphenylphosphorylmethyl)succinic acid are respectively subjected to a pre-condensation reaction with a diol.

5. The preparation method according to claim 1 or 4, characterized in that In step S1, the molar ratio of the reactive phosphorus-based flame retardant to the diol in S1 is 1:2-8, and the added amount of the reactive phosphorus-based flame retardant calculated as phosphorus element is 5000-10000 ppm of the theoretical output of the low-temperature cationic dyeable flame-retardant polyester.

6. The preparation method according to claim 1, characterized in that In step S1, an alkaline compound is added during the pre-polycondensation reaction, and the added amount is 0.1~1wt% of the diol in S1; in step S2, an alkaline compound is added during the pre-esterification reaction, and the added amount is 0.1~1wt% of the diol in S2.

7. The preparation method according to claim 1, characterized in that In step S2, the temperature of the pre-esterification reaction is 140~200°C, the pressure is 10~80kPa, and the reaction time is 2~4h; the molar ratio of the dibasic acid containing sulfonic acid groups to the diol in S2 is 1:2~8, and the added amount of the dibasic acid containing sulfonic acid groups accounts for 1~3mol% of the total added amount of the dibasic acid containing sulfonic acid groups and the dibasic acid.

8. The preparation method according to claim 1, characterized in that The specific process of step S3 includes: mixing the S1 product, dibasic acid, diol and catalyst, performing esterification reaction, then adding the S2 product, performing polycondensation reaction, and obtaining low-temperature cationic dyeable flame-retardant polyester.

9. The preparation method according to claim 8, characterized in that In step S3, when adding the product of S2, polyether is also added, and the amount of polyether added is 0.5-5.0 wt% of the theoretical output of the low-temperature cationic dyeable flame-retardant polyester.

10. The preparation method according to claim 8, characterized in that In step S3, the catalyst is an antimony catalyst and / or a titanium catalyst; the temperature of the esterification reaction is 240~250°C, the pressure is 250~350kPa, and the time is 2~3h; the temperature of the polycondensation reaction is 275~280°C, the pressure is -100~-80kPa, and the time is 2~3h.

Images