Preparation method of high-transparency fluorescent polyester fiber

Abstract

This invention relates to a method for preparing high-transmittance fluorescent polyester fibers. First, thiazopyridine diacid and ethanolamine are coupled via an active ester to prepare thiazopyridine diacid bis(hydroxyacetamide). Then, using purified terephthalic acid, ethylene glycol, and 1,4-cyclohexanediol as monomers, an esterification reaction is carried out to generate bis(hydroxyethyl) terephthalate and bis(hydroxymethyl)cyclohexyl terephthalate. Next, bis(hydroxyethyl) terephthalate, bis(hydroxymethyl)cyclohexyl terephthalate, and thiazopyridine diacid bis(hydroxyacetamide) are subjected to a co-condensation reaction to obtain high-transmittance PETG fluorescent copolyester chips containing thiazopyridine luminescent groups on the main chain. Finally, the PETG fluorescent copolyester chips and PET chips are melt-blended and spun to obtain high-transmittance fluorescent polyester fibers. This method avoids the problems of inorganic phosphor agglomeration in polyester fibers and the weak light transmittance of crystalline polyesters that severely affect fluorescence intensity in conventional direct blending methods.

Description

Technical Field

[0001] This invention belongs to the field of polyester fiber production and relates to a method for preparing high-transmittance fluorescent polyester fiber. Background Technology

[0002] Fluorescent fibers are widely used in clothing, anti-counterfeiting, and sensors due to their photoresponsive properties. Traditional fluorescent fibers are typically produced by physically blending fluorescent powder into a polymer matrix, followed by melt spinning or solution spinning techniques. However, commonly used inorganic fluorescent powders have poor compatibility with the fiber-forming polymers, resulting in uneven dispersion and agglomeration, leading to fluorescence quenching and decreased fiber mechanical properties. Furthermore, during service, fluorescent powder particles can migrate to the fiber surface or detach, making the fabric's fluorescence highly susceptible to environmental influences and potentially causing it to lose its fluorescent function. For common polyester fibers, due to their high processing temperatures, rare-earth fluorescent powders are currently primarily used in melt spinning with polyester to prepare fluorescent fibers, as illustrated in Chinese patents 00118517.9 and 201810391667.7. Chinese patent 00136273.9 uses a "dyeing solution" of dissolved organic small-molecule fluorescent substances in an organic solvent to directly "dye" polyester fibers, but the durability of the fluorescent substance remains an issue. Furthermore, for conventional PET polyester fibers, the presence of crystalline regions and matting agents causes light scattering, reducing the bulk fluorescence intensity. Therefore, developing a polyester fiber with covalently bonded fluorescent molecules and a transparent matrix can effectively solve this prevalent problem. Summary of the Invention

[0003] In view of the above problems, the purpose of this invention is to develop a high-transmittance fluorescent polyester fiber, wherein the organic fluorescent small molecules have high thermal stability and can be randomly copolymerized at high temperature to form a high-transmittance polyester macromolecular backbone, and then the high-transmittance fluorescent fiber is obtained by melt spinning.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A method for preparing a high-transmittance fluorescent polyester fiber includes the following steps: (1) Thiazole pyridine dicarboxylic acid (TPDA) was prepared by coupling thiazopyridine dicarboxylic acid (TPDA) with ethanolamine via an active ester. (2) Using purified terephthalic acid (PTA), ethylene glycol (EG) and 1,4-cyclohexanediol (CHDM) as polymerization monomers, esterification reaction is carried out to generate diethyl terephthalate (BHET) and dimethyl cyclohexyl terephthalate (BHCT). (3) Diethyl terephthalate, dimethyl terephthalate, and thiazopyridine diacid acetamide were co-polymerized to obtain high-transmittance PETG fluorescent copolyester chips containing thiazopyridine (TP) luminescent groups on the main chain. (4) The PETG fluorescent copolyester chips obtained in step (3) are melt-blended and spun with PET chips to obtain high-transmittance fluorescent polyester fibers; The bulk transmittance of high-transmittance fluorescent polyester fiber is indirectly represented by the crystallinity measured by differential scanning calorimetry (DSC). A crystallinity of 2-9% indicates high transmittance.

[0005] As a preferred technical solution: In the above-described method for preparing a high-transmittance fluorescent polyester fiber, in step (1), thiazopyridine dicarboxylic acid and N-hydroxysuccinimide (NHS) are first reacted under the action of condensing agent N,N-dicyclohexylcarbodiimide (DCC) to prepare TPDA active ester (TPDA-NHS); then, TPDA active ester is reacted with ethanolamine to prepare thiazopyridine dicarboxylic acid bis(hydroxyacetamide); wherein, the molar ratio of thiazopyridine dicarboxylic acid, N-hydroxysuccinimide and N,N-dicyclohexylcarbodiimide is 1:2.2:2.2, and the molar ratio of TPDA active ester to ethanolamine is 1:2.2.

[0006] The preparation method of a high-transmittance fluorescent polyester fiber as described above, the specific process of step (1) is as follows: Thiazole pyridine dicarboxylic acid and N-hydroxysuccinimide are dissolved in anhydrous acetone to form solution A, and N,N-dicyclohexylcarbodiimide is dissolved in anhydrous acetone to form solution B; solution A is stirred in an ice-water bath, and solution B is added dropwise to solution A at a rate of 0.5 mL / min. After the addition is completed, the reaction continues for 12 hours. Byproducts are removed by vacuum filtration, and the product is purified by ether precipitation and acetone dissolution to obtain TPDA active ester; TPDA active ester is then dissolved in acetone, stirred in an ice-water bath, and ethanolamine acetone solution is slowly added dropwise at a rate of 0.3 mL / min. After the addition is completed, the temperature is raised to room temperature and the reaction continues for 4 hours. The product is purified by ether precipitation and acetone dissolution to obtain thiazopyridine dicarboxylic acid bis(hydroxyacetamide).

[0007] The method for preparing high-transmittance fluorescent polyester fiber described above uses thiazopyridine dihydroxyacetamide, which has a thermal decomposition temperature of 315°C, significantly higher than that of TPDA (250°C). Therefore, it can meet the high-temperature requirements for PETG copolyester synthesis and fiber processing.

[0008] In the preparation method of the high-transmittance fluorescent polyester fiber described above, in step (2), purified terephthalic acid, ethylene glycol and 1,4-cyclohexanediethanol are mixed into a slurry, and antimony trioxide (Sb2O3) catalyst is added. The esterification reaction is carried out at a temperature of 240~260℃ and a pressure of 0.1 MPa for 4~6 h to generate BHET and BHCT. The molar ratio of purified terephthalic acid to glycol is 1:1.2~1.8, the glycol is ethylene glycol and 1,4-cyclohexanediethanol, and the molar fraction of 1,4-cyclohexanediethanol in the glycol is 30~60%. The amount of antimony trioxide added is 0.05 wt% of the total reactants.

[0009] In the above-described method for preparing a high-transmittance fluorescent polyester fiber, the molar ratio of purified terephthalic acid to thiazopyridine diacetamide is 1:0.02~0.1.

[0010] In the preparation method of the high-transmittance fluorescent polyester fiber described above, in step (3), diethyl terephthalate, dimethyl cyclohexyl terephthalate and thiazopyridine diacetamide are mixed and then antimony triacetate (Sb(OAC)3) catalyst is added. The vacuum is evacuated to below 500 Pa and reacted at a temperature of 260~270℃ for 30~50 minutes. Then the vacuum is continued to be evacuated to a pressure of less than 50 Pa and reacted at a temperature of 270~280℃ for 50~90 minutes to obtain PETG fluorescent copolyester chips. The amount of antimony triacetate added is 0.02 wt% of the total reactants. The intrinsic viscosity of the PETG fluorescent copolyester chips is 0.86~0.89 dL / g.

[0011] In the above-described method for preparing a high-transmittance fluorescent polyester fiber, in step (4), the spinning temperature of melt blending spinning is 245~265℃, the spinning speed is 4000~4500 m / min, the draw ratio is 1.7~2.2 times, the cooling air temperature is 20℃, the cooling air speed is 0.55 m / s, and the winding tension is 5~5.5 cN.

[0012] In the preparation method of a high-transmittance fluorescent polyester fiber as described above, in step (4), the mass fraction of PET chips is 25-35%, based on the total amount of PETG fluorescent copolyester chips and PET chips.

[0013] The method for preparing high-transmittance fluorescent polyester fiber as described above, wherein the tensile strength of the high-transmittance fluorescent polyester fiber is ≥3.5 cN / dtex; In high-transmittance fluorescent polyester fibers, thiazopyridine luminescent groups are covalently bonded to the main chain of PETG fluorescent copolyester and randomly distributed. There is no fluorescent molecule migration phenomenon, nor is there any fluorescence quenching phenomenon caused by TP molecule aggregation. High-transmittance fluorescent polyester fibers emit blue light under 365 nm ultraviolet light irradiation.

[0014] The TP luminescent group absorbs 250~400 nm ultraviolet light and generates blue fluorescence through radiative transition. The molecular structure of the TP luminescent group is similar to that of pyridone light stabilizers, and it has the function of absorbing ultraviolet light and inhibiting the photo-aging degradation of polyester fibers.

[0015] The principle of this invention is as follows: TPDA is an organic fluorescent small molecule compound, but its thermal decomposition temperature is only 250℃, making it unsuitable as a comonomer for direct esterification synthesis of copolyesters at polymerization temperatures above 260℃. This invention first reacts TPDA with ethanolamine via a mild coupling reaction to generate amide bonds with higher bond energy and greater stability, replacing the ester bonds to obtain TPDAEA with a decomposition temperature greater than 300℃ and active hydroxyl groups at the end. This TPDAEA can then be used as a comonomer to undergo polycondensation with BHET and BHCT to produce a high-transmittance PETG copolyester with fluorescent properties. Subsequently, the PETG copolyester is melt-blended with PET to obtain PETG / PET high-transmittance fluorescent polyester fibers. This method uses a simple co-condensation method to covalently bond fluorescent groups into the macromolecular backbone of the polyester, overcoming the disadvantages of simple fluorescent material mixing, which easily leads to migration and instability. Simultaneously, controlling the composition ensures high fiber transmittance, avoiding fluorescence loss caused by light scattering.

[0016] Beneficial effects: (1) The present invention prepares a high-transmittance polyester with fluorescent groups in the main chain through a simple copolymerization method. It not only has the function of photoluminescence, but also has the function of ultraviolet shielding. At the same time, the covalent bond makes the luminescent material stable and does not migrate. The high transmittance of the fiber matrix reduces light loss.

[0017] (2) The present invention can achieve better light transmittance by controlling the CHDM content to 30~60%.

[0018] (3) By controlling the PET content to 25-35%, the present invention can ensure good spinnability and produce fluorescent polyester fibers with high light transmittance.

[0019] (4) The high-transmittance fluorescent polyester fiber obtained by the present invention has important applications in high-end fields such as clothing and anti-counterfeiting. Attached Figure Description

[0020] Figure 1 The reaction equation for the PETG fluorescent copolyester of this invention is shown below. Detailed Implementation

[0021] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0022] In this invention: The tensile strength of the fiber was tested in accordance with GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments"; The intrinsic viscosity of PETG fluorescent copolyester chips was determined in accordance with GB / T 14190-2017 "Test Methods for Fiber Grade Polyester (PET) Chips"; The thermal decomposition temperature of the third monomer, thiazopyridine diacetate, was determined by thermogravimetric analysis (TGA) under nitrogen atmosphere and heating rate of 10 °C / min. The temperature at which 5% weight loss occurred on the TGA curve was recorded as the thermal decomposition temperature. The crystallinity was determined using a differential scanning calorimeter to represent the light transmittance of the fluorescent polyester fiber; the high-transmittance fluorescent polyester fiber was irradiated with a 365 nm ultraviolet lamp to observe its fluorescence emission; and the fluorescence emission spectrum of the fiber under 365 nm ultraviolet light excitation was determined using a fluorescence spectrometer.

[0023] Example 1

[0024] A method for preparing high-transmittance fluorescent polyester fiber, such as... Figure 1 As shown, the specific steps are as follows: (1) Preparation of the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA); (1.1) Active ester coupling reaction: Thiazolylpyridine dicarboxylic acid (TPDA) and N-hydroxysuccinimide (NHS) were dissolved in anhydrous acetone to form solution A, and the condensing agent N,N-dicyclohexylcarbodiimide (DCC) was dissolved in anhydrous acetone to form solution B; solution A was stirred in an ice-water bath, and solution B was slowly added dropwise to solution A at a rate of 0.5 mL / min. After the addition was completed, the reaction was continued for 12 h. Byproducts were removed by vacuum filtration, and the product was purified by precipitation with diethyl ether and dissolution with acetone to obtain TPDA active ester (TPDA-NHS); wherein the molar ratio of TPDA, NHS and DCC was 1:2.2:2.2; (1.2) Amide reaction: TPDA-NHS was dissolved in acetone and stirred in an ice-water bath. An acetone solution of ethanolamine was slowly added dropwise at a rate of 0.3 mL / min. After the addition was completed, the temperature was raised to room temperature and the reaction continued for 4 h. The product was purified by precipitation with ice-cold ether and dissolution in acetone to obtain the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA). The molar ratio of TPDA-NHS to ethanolamine was 1:2.2. Thermogravimetric analysis showed that the thermal decomposition temperature of the prepared third monomer TPDAEA was 315℃. (2) Esterification reaction: Purified terephthalic acid (PTA), ethylene glycol (EG) and 1,4-cyclohexanediol (CHDM) were mixed into a slurry, and antimony trioxide (Sb2O3) was added as a catalyst. The esterification reaction was carried out at a temperature of 240℃ and a pressure of 0.1 MPa for 6 h to produce diethyl terephthalate (BHET) and dimethyl cyclohexyl terephthalate (BHCT). The molar ratio of PTA to glycol was 1:1.2, the glycols were EG and CHDM, the molar fraction of CHDM in the glycols was 30%, and the amount of Sb2O3 added was 0.05 wt% of the total reactants. (3) Copolymerization reaction: BHET and BHCT obtained in step (2) and TPDAEA obtained in step (1) were mixed and antimony triacetate (Sb(OAc)3) catalyst was added. The mixture was evacuated to 500 Pa and reacted at 260°C for 50 min. Then, the mixture was evacuated to 49 Pa and reacted at 270°C for 90 min to obtain PETG fluorescent copolyester chips containing thiazopyridine (TP) luminescent groups on the main chain. The molar ratio of PTA to TPDAEA was 1:0.02, and the amount of Sb(OAc)3 added was 0.02 wt% of the total reactants. The intrinsic viscosity of PETG fluorescent copolyester chips was measured to be 0.89 dL / g. (4) Melt blending and spinning: The PETG fluorescent copolyester chips obtained in step (3) and PET chips are dried and then melt blended and spun to obtain high-transmittance fluorescent polyester fibers; wherein, based on the total amount of PETG fluorescent copolyester chips and PET chips, the mass fraction of PET chips is 25%; the spinning process parameters are as follows: The spinning temperature is 245℃; The spinning speed is 4000 m / min; The draw ratio is 1.7. The cooling air temperature is 20℃, and the cooling air velocity is 0.55 m / s; The winding tension is 5 cN.

[0025] In the final high-transmittance fluorescent polyester fiber, the thiazopyridine luminescent groups are covalently bonded to the main chain of the PETG fluorescent copolyester and randomly distributed. The tensile strength of the high-transmittance fluorescent polyester fiber is 4.5 cN / dtex; The crystallinity of the high-transmittance fluorescent polyester fiber is 3%; The fluorescence emission wavelength of the high-transmittance fluorescent polyester fiber appears in the range of 400-500 nm (excited at 365 nm wavelength), corresponding to blue fluorescence.

[0026] Example 2

[0027] A method for preparing high-transmittance fluorescent polyester fiber, the specific steps of which are as follows: (1) Preparation of the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA); (1.1) Active ester coupling reaction: Thiazolylpyridine dicarboxylic acid (TPDA) and N-hydroxysuccinimide (NHS) were dissolved in anhydrous acetone to form solution A, and the condensing agent N,N-dicyclohexylcarbodiimide (DCC) was dissolved in anhydrous acetone to form solution B; solution A was stirred in an ice-water bath, and solution B was slowly added dropwise to solution A at a rate of 0.5 mL / min. After the addition was completed, the reaction was continued for 12 h. Byproducts were removed by vacuum filtration, and the product was purified by precipitation with diethyl ether and dissolution with acetone to obtain TPDA active ester (TPDA-NHS); wherein the molar ratio of TPDA, NHS and DCC was 1:2.2:2.2; (1.2) Amide reaction: TPDA-NHS was dissolved in acetone and stirred in an ice-water bath. An acetone solution of ethanolamine was slowly added dropwise at a rate of 0.3 mL / min. After the addition was completed, the temperature was raised to room temperature and the reaction continued for 4 h. The product was purified by precipitation with ice-cold ether and dissolution in acetone to obtain the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA). The molar ratio of TPDA-NHS to ethanolamine was 1:2.2. Thermogravimetric analysis showed that the thermal decomposition temperature of the prepared third monomer TPDAEA was 315℃. (2) Esterification reaction: Purified terephthalic acid (PTA), ethylene glycol (EG) and 1,4-cyclohexanediol (CHDM) were mixed into a slurry, and antimony trioxide (Sb2O3) was added as a catalyst. The esterification reaction was carried out at a temperature of 245℃ and a pressure of 0.1 MPa for 6 h to produce diethyl terephthalate (BHET) and dimethyl cyclohexyl terephthalate (BHCT). The molar ratio of PTA to glycol was 1:1.3, the glycols were EG and CHDM, the molar fraction of CHDM in the glycols was 40%, and the amount of Sb2O3 added was 0.05 wt% of the total reactants. (3) Copolymerization reaction: BHET and BHCT obtained in step (2) and TPDAEA obtained in step (1) were mixed and antimony triacetate (Sb(OAc)3) catalyst was added. The mixture was evacuated to 495 Pa and reacted at 262 °C for 48 min. The mixture was then evacuated to 48 Pa and reacted at 272 °C for 87 min to obtain PETG fluorescent copolyester chips containing thiazopyridine (TP) luminescent groups on the main chain. The molar ratio of PTA to TPDAEA was 1:0.03, and the amount of Sb(OAc)3 added was 0.02 wt% of the total reactants. The intrinsic viscosity of PETG fluorescent copolyester chips was measured to be 0.89 dL / g. (4) Melt blending and spinning: The PETG fluorescent copolyester chips obtained in step (3) and PET chips are dried and then melt blended and spun to obtain high-transmittance fluorescent polyester fibers; wherein, based on the total amount of PETG fluorescent copolyester chips and PET chips, the mass fraction of PET chips is 25%; the spinning process parameters are as follows: The spinning temperature is 248℃; The spinning speed is 4150 m / min; The draw ratio is 1.8. The cooling air temperature is 20℃, and the cooling air velocity is 0.55 m / s; The winding tension is 5.1 cN.

[0028] In the final high-transmittance fluorescent polyester fiber, the thiazopyridine luminescent groups are covalently bonded to the main chain of the PETG fluorescent copolyester and randomly distributed. The tensile strength of the high-transmittance fluorescent polyester fiber is 4.1 cN / dtex; The crystallinity of the high-transmittance fluorescent polyester fiber is 2%; The fluorescence emission wavelength of the high-transmittance fluorescent polyester fiber appears in the range of 400-500 nm (excited at 365 nm wavelength), corresponding to blue fluorescence.

[0029] Example 3

[0030] A method for preparing high-transmittance fluorescent polyester fiber, the specific steps of which are as follows: (1) Preparation of the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA); (1.1) Active ester coupling reaction: Thiazolylpyridine dicarboxylic acid (TPDA) and N-hydroxysuccinimide (NHS) were dissolved in anhydrous acetone to form solution A, and the condensing agent N,N-dicyclohexylcarbodiimide (DCC) was dissolved in anhydrous acetone to form solution B; solution A was stirred in an ice-water bath, and solution B was slowly added dropwise to solution A at a rate of 0.5 mL / min. After the addition was completed, the reaction was continued for 12 h. Byproducts were removed by vacuum filtration, and the product was purified by precipitation with diethyl ether and dissolution with acetone to obtain TPDA active ester (TPDA-NHS); wherein the molar ratio of TPDA, NHS and DCC was 1:2.2:2.2; (1.2) Amide reaction: TPDA-NHS was dissolved in acetone and stirred in an ice-water bath. An acetone solution of ethanolamine was slowly added dropwise at a rate of 0.3 mL / min. After the addition was completed, the temperature was raised to room temperature and the reaction continued for 4 h. The product was purified by precipitation with ice-cold ether and dissolution in acetone to obtain the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA). The molar ratio of TPDA-NHS to ethanolamine was 1:2.2. Thermogravimetric analysis showed that the thermal decomposition temperature of the prepared third monomer TPDAEA was 315℃. (2) Esterification reaction: Purified terephthalic acid (PTA), ethylene glycol (EG) and 1,4-cyclohexanediol (CHDM) were mixed into a slurry, and antimony trioxide (Sb2O3) was added as a catalyst. The esterification reaction was carried out at a temperature of 248℃ and a pressure of 0.1 MPa for 5 h to produce diethyl terephthalate (BHET) and dimethyl cyclohexyl terephthalate (BHCT). The molar ratio of PTA to glycol was 1:1.4, the glycols were EG and CHDM, the molar fraction of CHDM in the glycols was 45%, and the amount of Sb2O3 added was 0.05 wt% of the total reactants. (3) Copolymerization reaction: BHET and BHCT obtained in step (2) and TPDAEA obtained in step (1) were mixed and antimony triacetate (Sb(OAc)3) catalyst was added. The mixture was evacuated to 490 Pa and reacted at 265 °C for 42 min. Then, the mixture was evacuated to 46 Pa and reacted at 275 °C for 80 min to obtain PETG fluorescent copolyester chips containing thiazopyridine (TP) luminescent groups on the main chain. The molar ratio of PTA to TPDAEA was 1:0.05, and the amount of Sb(OAc)3 added was 0.02 wt% of the total reactants. The intrinsic viscosity of PETG fluorescent copolyester chips was measured to be 0.88 dL / g. (4) Melt blending and spinning: The PETG fluorescent copolyester chips obtained in step (3) and PET chips are dried and then melt blended and spun to obtain high-transmittance fluorescent polyester fibers; wherein, based on the total amount of PETG fluorescent copolyester chips and PET chips, the mass fraction of PET chips is 30%; the spinning process parameters are as follows: The spinning temperature is 250℃; The spinning speed is 4250 m / min; The draw ratio is 1.9. The cooling air temperature is 20℃, and the cooling air velocity is 0.55 m / s; The winding tension is 5.2 cN.

[0031] In the final high-transmittance fluorescent polyester fiber, the thiazopyridine luminescent groups are covalently bonded to the main chain of the PETG fluorescent copolyester and randomly distributed. The tensile strength of the high-transmittance fluorescent polyester fiber is 3.9 cN / dtex; The crystallinity of the high-transmittance fluorescent polyester fiber is 5%; The fluorescence emission wavelength of the high-transmittance fluorescent polyester fiber appears in the range of 400-500 nm (excited at 365 nm wavelength), corresponding to blue fluorescence.

[0032] Example 4

[0033] A method for preparing high-transmittance fluorescent polyester fiber, the specific steps of which are as follows: (1) Preparation of the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA); (1.1) Active ester coupling reaction: Thiazolylpyridine dicarboxylic acid (TPDA) and N-hydroxysuccinimide (NHS) were dissolved in anhydrous acetone to form solution A, and the condensing agent N,N-dicyclohexylcarbodiimide (DCC) was dissolved in anhydrous acetone to form solution B; solution A was stirred in an ice-water bath, and solution B was slowly added dropwise to solution A at a rate of 0.5 mL / min. After the addition was completed, the reaction was continued for 12 h. Byproducts were removed by vacuum filtration, and the product was purified by precipitation with diethyl ether and dissolution with acetone to obtain TPDA active ester (TPDA-NHS); wherein the molar ratio of TPDA, NHS and DCC was 1:2.2:2.2; (1.2) Amide reaction: TPDA-NHS was dissolved in acetone and stirred in an ice-water bath. An acetone solution of ethanolamine was slowly added dropwise at a rate of 0.3 mL / min. After the addition was completed, the temperature was raised to room temperature and the reaction continued for 4 h. The product was purified by precipitation with ice-cold ether and dissolution in acetone to obtain the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA). The molar ratio of TPDA-NHS to ethanolamine was 1:2.2. Thermogravimetric analysis showed that the thermal decomposition temperature of the prepared third monomer TPDAEA was 315℃. (2) Esterification reaction: Purified terephthalic acid (PTA), ethylene glycol (EG) and 1,4-cyclohexanediol (CHDM) were mixed into a slurry, and antimony trioxide (Sb2O3) was added as a catalyst. The esterification reaction was carried out at a temperature of 250℃ and a pressure of 0.1 MPa for 5 h to produce diethyl terephthalate (BHET) and dimethyl cyclohexyl terephthalate (BHCT). The molar ratio of PTA to glycol was 1:1.5, the glycols were EG and CHDM, the molar fraction of CHDM in the glycols was 50%, and the amount of Sb2O3 added was 0.05 wt% of the total reactants. (3) Copolymerization reaction: BHET and BHCT obtained in step (2) and TPDAEA obtained in step (1) were mixed and antimony triacetate (Sb(OAc)3) catalyst was added. The mixture was evacuated to 480 Pa and reacted at 268 °C for 36 min. Then, the mixture was evacuated to 45 Pa and reacted at 277 °C for 70 min to obtain PETG fluorescent copolyester chips containing thiazopyridine (TP) luminescent groups on the main chain. The molar ratio of PTA to TPDAEA was 1:0.08, and the amount of Sb(OAc)3 added was 0.02 wt% of the total reactants. The intrinsic viscosity of PETG fluorescent copolyester chips was measured to be 0.87 dL / g. (4) Melt blending and spinning: The PETG fluorescent copolyester chips obtained in step (3) and PET chips are dried and then melt blended and spun to obtain high-transmittance fluorescent polyester fibers; wherein, based on the total amount of PETG fluorescent copolyester chips and PET chips, the mass fraction of PET chips is 30%; the spinning process parameters are as follows: The spinning temperature is 255℃; The spinning speed is 4300 m / min; The draw ratio is 2.0. The cooling air temperature is 20℃, and the cooling air velocity is 0.55 m / s; The winding tension is 5.3 cN.

[0034] In the final high-transmittance fluorescent polyester fiber, the thiazopyridine luminescent groups are covalently bonded to the main chain of the PETG fluorescent copolyester and randomly distributed. The tensile strength of the high-transmittance fluorescent polyester fiber is 3.8 cN / dtex; The crystallinity of the high-transmittance fluorescent polyester fiber is 4%; The fluorescence emission wavelength of the high-transmittance fluorescent polyester fiber appears in the range of 400-500 nm (excited at 365 nm wavelength), corresponding to blue fluorescence.

[0035] Example 5

[0036] A method for preparing high-transmittance fluorescent polyester fiber, the specific steps of which are as follows: (1) Preparation of the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA); (1.1) Active ester coupling reaction: Thiazolylpyridine dicarboxylic acid (TPDA) and N-hydroxysuccinimide (NHS) were dissolved in anhydrous acetone to form solution A, and the condensing agent N,N-dicyclohexylcarbodiimide (DCC) was dissolved in anhydrous acetone to form solution B; solution A was stirred in an ice-water bath, and solution B was slowly added dropwise to solution A at a rate of 0.5 mL / min. After the addition was completed, the reaction was continued for 12 h. Byproducts were removed by vacuum filtration, and the product was purified by precipitation with diethyl ether and dissolution with acetone to obtain TPDA active ester (TPDA-NHS); wherein the molar ratio of TPDA, NHS and DCC was 1:2.2:2.2; (1.2) Amide reaction: TPDA-NHS was dissolved in acetone and stirred in an ice-water bath. An acetone solution of ethanolamine was slowly added dropwise at a rate of 0.3 mL / min. After the addition was completed, the temperature was raised to room temperature and the reaction continued for 4 h. The product was purified by precipitation with ice-cold ether and dissolution in acetone to obtain the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA). The molar ratio of TPDA-NHS to ethanolamine was 1:2.2. Thermogravimetric analysis showed that the thermal decomposition temperature of the prepared third monomer TPDAEA was 315℃. (2) Esterification reaction: Purified terephthalic acid (PTA), ethylene glycol (EG) and 1,4-cyclohexanediol (CHDM) were mixed into a slurry, and antimony trioxide (Sb2O3) catalyst was added. The esterification reaction was carried out for 4.5 h at a temperature of 255℃ and a pressure of 0.1 MPa to produce diethyl terephthalate (BHET) and dimethyl cyclohexyl terephthalate (BHCT). The molar ratio of PTA to glycol was 1:1.6, the glycols were EG and CHDM, the molar fraction of CHDM in the glycols was 55%, and the amount of Sb2O3 added was 0.05 wt% of the total reactants. (3) Copolymerization reaction: BHET and BHCT obtained in step (2) and TPDAEA obtained in step (1) were mixed and antimony triacetate (Sb(OAc)3) catalyst was added. The mixture was evacuated to 480 Pa and reacted at 270 °C for 30 min. Then, the mixture was evacuated to 45 Pa and reacted at 278 °C for 60 min to obtain PETG fluorescent copolyester chips containing thiazopyridine (TP) luminescent groups on the main chain. The molar ratio of PTA to TPDAEA was 1:0.09, and the amount of Sb(OAc)3 added was 0.02 wt% of the total reactants. The intrinsic viscosity of PETG fluorescent copolyester chips was measured to be 0.86 dL / g. (4) Melt blending and spinning: The PETG fluorescent copolyester chips obtained in step (3) and PET chips are dried and then melt blended and spun to obtain high-transmittance fluorescent polyester fibers; wherein, based on the total amount of PETG fluorescent copolyester chips and PET chips, the mass fraction of PET chips is 35%; the spinning process parameters are as follows: The spinning temperature is 260℃; The spinning speed is 4400 m / min; The draw ratio is 2.1 times; The cooling air temperature is 20℃, and the cooling air velocity is 0.55 m / s; The winding tension is 5.4 cN.

[0037] In the final high-transmittance fluorescent polyester fiber, the thiazopyridine luminescent groups are covalently bonded to the main chain of the PETG fluorescent copolyester and randomly distributed. The tensile strength of the high-transmittance fluorescent polyester fiber is 3.7 cN / dtex; The crystallinity of the high-transmittance fluorescent polyester fiber is 8%; The fluorescence emission wavelength of the high-transmittance fluorescent polyester fiber appears in the range of 400-500 nm (excited at 365 nm wavelength), corresponding to blue fluorescence.

[0038] Example 6

[0039] A method for preparing high-transmittance fluorescent polyester fiber, the specific steps of which are as follows: (1) Preparation of the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA); (1.1) Active ester coupling reaction: Thiazolylpyridine dicarboxylic acid (TPDA) and N-hydroxysuccinimide (NHS) were dissolved in anhydrous acetone to form solution A, and the condensing agent N,N-dicyclohexylcarbodiimide (DCC) was dissolved in anhydrous acetone to form solution B; solution A was stirred in an ice-water bath, and solution B was slowly added dropwise to solution A at a rate of 0.5 mL / min. After the addition was completed, the reaction was continued for 12 h. Byproducts were removed by vacuum filtration, and the product was purified by precipitation with diethyl ether and dissolution with acetone to obtain TPDA active ester (TPDA-NHS); wherein the molar ratio of TPDA, NHS and DCC was 1:2.2:2.2; (1.2) Amide reaction: TPDA-NHS was dissolved in acetone and stirred in an ice-water bath. An acetone solution of ethanolamine was slowly added dropwise at a rate of 0.3 mL / min. After the addition was completed, the temperature was raised to room temperature and the reaction continued for 4 h. The product was purified by precipitation with ice-cold ether and dissolution in acetone to obtain the third monomer, thiazopyridine diacetate bis(hydroxyacetamide) (TPDAEA). The molar ratio of TPDA-NHS to ethanolamine was 1:2.2. Thermogravimetric analysis showed that the thermal decomposition temperature of the prepared third monomer TPDAEA was 315℃. (2) Esterification reaction: Purified terephthalic acid (PTA), ethylene glycol (EG) and 1,4-cyclohexanediol (CHDM) were mixed into a slurry, and antimony trioxide (Sb2O3) was added as a catalyst. The esterification reaction was carried out at a temperature of 260℃ and a pressure of 0.1 MPa for 4 h to produce diethyl terephthalate (BHET) and dimethyl cyclohexyl terephthalate (BHCT). The molar ratio of PTA to glycol was 1:1.8, the glycols were EG and CHDM, the molar fraction of CHDM in the glycols was 60%, and the amount of Sb2O3 added was 0.05 wt% of the total reactants. (3) Copolymerization reaction: BHET and BHCT obtained in step (2) and TPDAEA obtained in step (1) were mixed and antimony triacetate (Sb(OAc)3) catalyst was added. The mixture was evacuated to 480 Pa and reacted at 270 °C for 30 min. Then, the mixture was evacuated to 45 Pa and reacted at 280 °C for 50 min to obtain PETG fluorescent copolyester chips containing thiazopyridine (TP) luminescent groups on the main chain. The molar ratio of PTA to TPDAEA was 1:0.1, and the amount of Sb(OAc)3 added was 0.02 wt% of the total reactants. The intrinsic viscosity of PETG fluorescent copolyester chips was measured to be 0.86 dL / g. (4) Melt blending and spinning: The PETG fluorescent copolyester chips obtained in step (3) and PET chips are dried and then melt blended and spun to obtain high-transmittance fluorescent polyester fibers; wherein, based on the total amount of PETG fluorescent copolyester chips and PET chips, the mass fraction of PET chips is 35%; the spinning process parameters are as follows: The spinning temperature is 265℃; The spinning speed is 4500 m / min; The draw ratio is 2.2 times; The cooling air temperature is 20℃, and the cooling air velocity is 0.55 m / s; The winding tension is 5.5 cN.

[0040] In the final high-transmittance fluorescent polyester fiber, the thiazopyridine luminescent groups are covalently bonded to the main chain of the PETG fluorescent copolyester and randomly distributed. The tensile strength of the high-transmittance fluorescent polyester fiber is 3.5 cN / dtex; The crystallinity of the high-transmittance fluorescent polyester fiber is 9%; The fluorescence emission wavelength of the high-transmittance fluorescent polyester fiber appears in the range of 400-500 nm (excited at 365 nm wavelength), corresponding to blue fluorescence.

Claims

1. A method for preparing high-transmittance fluorescent polyester fiber, characterized in that, Includes the following steps: (1) Thiazolepyridine diacetamide was prepared by coupling thiazopyridine diacetamide with ethanolamine via an active ester; (2) Using purified terephthalic acid, ethylene glycol and 1,4-cyclohexanediol as polymerization monomers, esterification reaction is carried out to generate diethyl terephthalate and dimethyl cyclohexyl terephthalate. (3) Diethyl terephthalate, dimethyl terephthalate, and thiazopyridine diacid acetamide were co-polymerized to obtain high-transmittance PETG fluorescent copolyester chips containing thiazopyridine luminescent groups on the main chain. (4) The PETG fluorescent copolyester chips obtained in step (3) are melt-blended and spun with PET chips to obtain high-transmittance fluorescent polyester fibers; The crystallinity of high-transmittance fluorescent polyester fiber is 2-9%.

2. The method for preparing a high-transmittance fluorescent polyester fiber according to claim 1, characterized in that, In step (1), thiazopyridine dicarboxylic acid and N-hydroxysuccinimide are first reacted with the condensing agent N,N-dicyclohexylcarbodiimide to prepare TPDA active ester; then, TPDA active ester is reacted with ethanolamine to prepare thiazopyridine dicarboxylic acid bis(hydroxyacetamide); wherein, the molar ratio of thiazopyridine dicarboxylic acid, N-hydroxysuccinimide and N,N-dicyclohexylcarbodiimide is 1:2.2:2.2, and the molar ratio of TPDA active ester to ethanolamine is 1:2.

2.

3. The method for preparing a high-transmittance fluorescent polyester fiber according to claim 2, characterized in that, The specific process of step (1) is as follows: Thiazolpyridine dicarboxylic acid and N-hydroxysuccinimide are dissolved in anhydrous acetone to form solution A, and N,N-dicyclohexylcarbodiimide is dissolved in anhydrous acetone to form solution B; solution A is stirred in an ice-water bath, and solution B is added dropwise to solution A at a rate of 0.5 mL / min. After the addition is completed, the reaction continues for 12 hours. Byproducts are removed by vacuum filtration, and the product is purified by ether precipitation and acetone dissolution to obtain TPDA active ester; TPDA active ester is then dissolved in acetone, stirred in an ice-water bath, and ethanolamine acetone solution is slowly added dropwise at a rate of 0.3 mL / min. After the addition is completed, the temperature is raised to room temperature and the reaction continues for 4 hours. The product is purified by ether precipitation and acetone dissolution to obtain thiazopyridine dicarboxylic acid bis(hydroxyacetamide).

4. The method for preparing a high-transmittance fluorescent polyester fiber according to claim 3, characterized in that, The thermal decomposition temperature of thiazopyridine dihydroxyacetamide is 315℃.

5. The method for preparing a high-transmittance fluorescent polyester fiber according to claim 1, characterized in that, In step (2), purified terephthalic acid, ethylene glycol, and 1,4-cyclohexanediethanol are mixed into a slurry, and antimony trioxide is added as a catalyst. The mixture is then subjected to esterification for 4-6 h at a temperature of 240-260℃ and a pressure of 0.1 MPa to produce BHET and BHCT. The molar ratio of purified terephthalic acid to glycol is 1:1.2-1.8, and the glycol is ethylene glycol and 1,4-cyclohexanediethanol. The molar fraction of 1,4-cyclohexanediethanol in the glycol is 30-60%. The amount of antimony trioxide added is 0.05 wt% of the total reactants.

6. The method for preparing a high-transmittance fluorescent polyester fiber according to claim 1, characterized in that, The molar ratio of purified terephthalic acid to thiazopyridine diacetamide is 1:0.02~0.

1.

7. The method for preparing a high-transmittance fluorescent polyester fiber according to claim 1, characterized in that, In step (3), diethyl terephthalate, dimethyl cyclohexyl terephthalate, and thiazopyridine diacetamide are mixed and then antimony triacetate is added as a catalyst. The mixture is evacuated to below 500 Pa and reacted at 260-270°C for 30-50 minutes. Then, the mixture is evacuated to below 50 Pa and reacted at 270-280°C for 50-90 minutes to obtain PETG fluorescent copolyester chips. The amount of antimony triacetate added is 0.02 wt% of the total reactants. The intrinsic viscosity of the PETG fluorescent copolyester chips is 0.86-0.89 dL / g.

8. The method for preparing a high-transmittance fluorescent polyester fiber according to claim 1, characterized in that, In step (4), the spinning temperature of melt blending spinning is 245~265℃, the spinning speed is 4000~4500 m / min, the draw ratio is 1.7~2.2 times, the cooling air temperature is 20℃, the cooling air speed is 0.55 m / s, and the winding tension is 5~5.5 cN.

9. The method for preparing a high-transmittance fluorescent polyester fiber according to claim 1, characterized in that, In step (4), the total amount of PETG fluorescent copolyester chips and PET chips is used as a basis, and the mass fraction of PET chips is 25~35%.

10. The method for preparing a high-transmittance fluorescent polyester fiber according to claim 1, characterized in that, The tensile strength of high-transmittance fluorescent polyester fiber is ≥3.5 cN / dtex; In the high-transmittance fluorescent polyester fiber, the thiazopyridine luminescent groups are covalently bonded to the main chain of the PETG fluorescent copolyester and randomly distributed; the high-transmittance fluorescent polyester fiber emits blue light under 365 nm ultraviolet light irradiation.

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