Preparation method of anti-ultraviolet RCGT elastic FDY (Fully Drawn Yarn)

Abstract

The invention relates to the technical field of polyester fibers, in particular to a preparation method of anti-ultraviolet RCGT elastic FDY. Comprising the following steps: S1, esterification: adding terephthalic acid, 1, 4-butanediol and concentrated sulfuric acid into an esterification reaction kettle, and heating the esterification reaction kettle to obtain an esterification product; s2, pre-polycondensation: adding the esterification product and ethylene glycol into a polycondensation reaction kettle, filling nitrogen into the polycondensation reaction kettle, heating the polycondensation reaction kettle, keeping the temperature and the pressure for 20-30 minutes, vacuumizing the polycondensation reaction kettle, heating, keeping the temperature and the pressure for 1-2 hours, and obtaining a pre-polycondensation product; s3, final polycondensation: continuing to vacuumize and heat the polycondensation reaction kettle, and keeping the temperature and pressure for 2-3 hours to obtain a melt; and S4, spinning: spinning the melt through a spinning machine to obtain the anti-ultraviolet RCGT elastic FDY. The compatibility of modified titanium dioxide and polyester is good, and the anti-ultraviolet RCGT elastic FDY can have good anti-ultraviolet performance and mechanical performance at the same time.

Description

Technical Field

[0001] The present invention relates to the technical field of polyester fibers, and in particular to a method for preparing UV-resistant RCGT elastic FDY. Background Art

[0002] RCGT stretch FDY is a fully stretched yarn (FDY) made by combining PBT (polybutylene terephthalate) with highly elastic materials. Due to its good elasticity, RCGT stretch FDY is widely used in the production of elastic clothing, such as sportswear, casual pants, etc. However, after these elastic clothing are used for a period of time, the fiber elasticity will decrease due to ultraviolet radiation, affecting the service life of the elastic clothing.

[0003] In order to improve the anti-ultraviolet performance of RCGT stretch FDY in the existing technology, ultraviolet shielding agents such as titanium dioxide and zinc oxide are added to PBT. The addition of these ultraviolet shielding agents will cause the elasticity and strength of the fiber to decrease, affecting the strength of the elastic clothing. There is also a method of attaching ultraviolet shielding agents to the fiber surface to improve the anti-ultraviolet performance, but the bonding strength between the ultraviolet shielding agent and the fiber is low. As the use time increases, these ultraviolet shielding agents will fall off, resulting in a significant decrease in the anti-ultraviolet performance of the fiber. Summary of the Invention

[0004] In order to solve the above problems, the present invention provides a method for preparing UV-resistant RCGT elastic FDY.

[0005] The technical solution of the present invention is: a method for preparing UV-resistant RCGT elastic FDY, comprising the following steps:

[0006] S1. Esterification

[0007] Add terephthalic acid, 1,4-butanediol, and concentrated sulfuric acid into an esterification reaction kettle in a mass ratio of 1:1.2-1.8:0.01-0.02, heat the esterification reaction kettle until the temperature inside the esterification reaction kettle reaches 180-200° C., keep warm and stir for 2-3 hours to obtain an esterification product;

[0008] S2, pre-condensation

[0009] S2-1. Add the esterification product and ethylene glycol into a polycondensation reactor, stir for 10 to 15 minutes, then fill the polycondensation reactor with nitrogen and heat the polycondensation reactor until the pressure in the polycondensation reactor reaches 0.3 to 0.4 MPa and the temperature reaches 80 to 100° C., then add p-toluenesulfonic acid into the polycondensation reactor, and then maintain the temperature and pressure for 20 to 30 minutes; wherein the mass ratio of the esterification product, ethylene glycol, and p-toluenesulfonic acid is 1:0.1 to 0.3:0.01 to 0.015;

[0010] S2-2, after the insulation is completed, the polycondensation reaction kettle is evacuated and heated, and the temperature in the polycondensation reaction kettle is increased by 25 to 30° C. for every 40 to 60 kPa drop in the pressure in the polycondensation reaction kettle, and the temperature is kept at this temperature and pressure for 10 to 15 minutes. During the insulation and pressure holding process, modified titanium dioxide is added to the polycondensation reaction kettle once until the temperature in the polycondensation reaction kettle reaches 200 to 240° C., then the temperature is kept and the addition of modified titanium dioxide is stopped, and the evacuation is continued until the pressure in the polycondensation reaction kettle reaches 1 to 2 kPa, and then the temperature is kept at this temperature and pressure for 1 to 2 hours to obtain a pre-condensation product; wherein, the single addition amount of modified titanium dioxide accounts for 0.05 to 0.08% of the total mass of the esterification product;

[0011] S3, final polycondensation

[0012] Continue to evacuate the polycondensation reactor and heat it until the pressure inside the polycondensation reactor reaches 100-200 Pa and the temperature reaches 270-290° C. After maintaining the temperature and pressure for 2-3 hours, a melt is obtained;

[0013] S4, Spinning

[0014] The melt is spun through a spinning machine, and then stretched, cooled, heat-set and wound in sequence to obtain UV-resistant RCGT stretch FDY.

[0015] Description: The above method prepares elastic polyester through esterification reaction of terephthalic acid and 1,4-butanediol, and then co-condensation with ethylene glycol. The addition of modified titanium dioxide enables the prepared UV-resistant RCGT elastic FDY to effectively reflect and absorb ultraviolet rays, and the modified titanium dioxide has good compatibility with polyester, avoiding the addition of titanium dioxide affecting the strength of the UV-resistant RCGT elastic FDY, so that the UV-resistant RCGT elastic FDY has good UV resistance and mechanical properties.

[0016] Furthermore, the preparation method of the modified titanium dioxide comprises the following steps:

[0017] 1) adding tetrabutyl titanate and vinyl acetate to anhydrous ethanol, and adjusting the pH value of the anhydrous ethanol to 2-4 using dilute hydrochloric acid to obtain a mixed solution; wherein the mass ratio of tetrabutyl titanate, vinyl acetate, and anhydrous ethanol is 1:1-2:5-6;

[0018] 2) stirring the mixture, and gradually adding deionized water to the mixture during the stirring process at a rate of 40 to 80 ml / min until the amount of deionized water added accounts for 10 to 20% of the total volume of the mixture. Stop adding deionized water and continue stirring for 30 to 40 minutes to obtain a mixed gel;

[0019] 3) After the mixed gel is allowed to stand for 12 to 16 hours, the mixed gel is washed and dried, and then calcined at 150 to 280° C. for 3 to 5 hours to obtain modified titanium dioxide.

[0020] Description: The modified titanium dioxide is prepared by hydrolysis and polycondensation of tetrabutyl titanate. At the same time, vinyl acetate can be co-condensed with tetrabutyl titanate to load vinyl acetate on the titanium dioxide to form an organic-inorganic hybrid layer, thereby improving the compatibility of titanium dioxide with polyester and enabling titanium dioxide to be evenly dispersed in the polyester matrix, thereby preventing the addition of titanium dioxide from affecting the strength of the UV-resistant RCGT elastic FDY.

[0021] Furthermore, the washing method is to rinse with deionized water.

[0022] Note: Using deionized water for rinsing can effectively remove the impurities remaining in the mixed gel to prevent the impurities from affecting the subsequent calcination.

[0023] Furthermore, the drying temperature is 90-120° C., and the drying time is 8-10 hours.

[0024] Note: The above drying parameters can ensure that the residual water in the mixed gel can be fully removed.

[0025] Furthermore, the spinning speed during the spinning is 900 to 1200 m / min.

[0026] Note: Limiting the spinning speed can ensure the crystallinity of the fiber and production efficiency, and avoid insufficient fiber crystallization affecting the strength of the UV-resistant RCGT elastic FDY.

[0027] Furthermore, the stretching ratio during the stretching is 3 to 4 times.

[0028] Note: Limiting the stretching ratio can control the orientation and crystallinity of the fiber, thereby ensuring the strength of the UV-resistant RCGT stretch FDY.

[0029] Furthermore, the cooling is performed using a high-speed airflow of 15 to 20 m / s.

[0030] Note: Limiting the air flow rate can ensure the cooling rate of the fiber and avoid large residual stress inside the fiber, which will lead to a decrease in dimensional stability in subsequent processing.

[0031] Furthermore, the heat setting temperature is 200-220°C.

[0032] Note: Limiting the heat setting temperature can fully eliminate the tensile stress inside the fiber and promote crystallization, avoiding affecting the strength of the UV-resistant RCGT stretch FDY.

[0033] The beneficial effects of the present invention are:

[0034] (1) The present invention prepares elastic polyester by esterification reaction between terephthalic acid and 1,4-butanediol, and then co-condensation with ethylene glycol. The addition of modified titanium dioxide enables the prepared anti-ultraviolet RCGT elastic FDY to effectively reflect and absorb ultraviolet rays, and the modified titanium dioxide has good compatibility with polyester, which can avoid excessive decrease in the strength of the anti-ultraviolet RCGT elastic FDY due to the addition of titanium dioxide, so that the anti-ultraviolet RCGT elastic FDY has good anti-ultraviolet light performance and mechanical properties.

[0035] (2) The present invention prepares titanium dioxide by hydrolysis and polycondensation of tetrabutyl titanate, and vinyl acetate can be co-condensed with tetrabutyl titanate at the same time, so that vinyl acetate is loaded on the titanium dioxide to form an organic-inorganic hybrid layer, thereby improving the compatibility of titanium dioxide and polyester, allowing titanium dioxide to be uniformly dispersed in the polyester matrix, and avoiding the addition of titanium dioxide affecting the strength of the anti-ultraviolet RCGT elastic FDY. DETAILED DESCRIPTION

[0036] In order to further illustrate the approach and effects achieved by the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with experiments.

[0037] Example 1: A method for preparing UV-resistant RCGT elastic FDY, comprising the following steps:

[0038] S1. Esterification

[0039] Terephthalic acid, 1,4-butanediol, and concentrated sulfuric acid are added to an esterification reaction kettle in a mass ratio of 1:1.6:0.015, and the esterification reaction kettle is heated until the temperature in the esterification reaction kettle reaches 190°C, and then kept warm and stirred for 2.5 hours. During the keeping warm period, a fractional distillation device is used to remove water produced during the reaction to obtain an esterification product; wherein the mass concentration of the concentrated sulfuric acid is 98%;

[0040] S2, pre-condensation

[0041] S2-1. Add the esterification product and ethylene glycol into a polycondensation reactor, stir for 12 minutes, then fill the polycondensation reactor with nitrogen and heat the polycondensation reactor until the pressure in the polycondensation reactor reaches 0.35 MPa and the temperature reaches 90°C. Then, add p-toluenesulfonic acid into the polycondensation reactor, and then maintain the temperature and pressure for 25 minutes; wherein the mass ratio of the esterification product, ethylene glycol, and p-toluenesulfonic acid is 1:0.2:0.012;

[0042] S2-2. After the insulation is completed, the polycondensation reactor is evacuated and heated. For every 50 kPa drop in the pressure in the polycondensation reactor, the temperature in the polycondensation reactor is increased by 28° C. and the reactor is kept warm and pressurized for 12 minutes. During the heat preservation and pressure holding process, modified titanium dioxide is added to the polycondensation reactor once until the temperature in the polycondensation reactor reaches 220° C., then the temperature is kept and the addition of modified titanium dioxide is stopped. The evacuation is continued until the pressure in the polycondensation reactor reaches 1.5 kPa, and then the temperature is kept warm and pressurized for 1.5 hours to obtain a pre-condensation product; wherein the single addition amount of modified titanium dioxide accounts for 0.07% of the total mass of the esterification product;

[0043] S3, final polycondensation

[0044] Continue to evacuate the polycondensation reactor and heat it until the pressure inside the polycondensation reactor reaches 150 Pa and the temperature reaches 280°C. After maintaining the temperature and pressure for 2.5 hours, a melt is obtained.

[0045] S4, Spinning

[0046] The melt is spun through a spinning machine, and then stretched, cooled, heat-set, and wound in sequence to obtain UV-resistant RCGT stretch FDY. The spinning speed is 1000 m / min, the stretching ratio is 3.5 times, the cooling is carried out by a high-speed airflow of 18 m / s, and the heat-setting temperature is 210°C.

[0047] The preparation method of modified titanium dioxide comprises the following steps:

[0048] 1) adding tetrabutyl titanate and vinyl acetate to anhydrous ethanol, and adjusting the pH value of the anhydrous ethanol to 3 using dilute hydrochloric acid to obtain a mixed solution; wherein the mass ratio of tetrabutyl titanate, vinyl acetate, and anhydrous ethanol is 1:1.5:5.5, and the mass concentration of the dilute hydrochloric acid is 2%;

[0049] 2) stirring the mixture, and gradually adding deionized water to the mixture at a rate of 60 ml / min until the amount of deionized water added accounts for 15% of the total volume of the mixture. Then, the addition of deionized water was stopped and stirring was continued for 35 minutes to obtain a mixed gel;

[0050] 3) After the mixed gel was allowed to stand for 14 hours, the mixed gel was washed and dried, and then calcined at 200° C. for 3 hours to obtain modified titanium dioxide; wherein the washing method is to rinse with deionized water, the drying temperature is 100° C., and the drying time is 9 hours.

[0051] Example 2: This example is basically the same as Example 1, except that terephthalic acid, 1,4-butanediol, and concentrated sulfuric acid are added into the esterification reaction kettle in a mass ratio of 1:1.2:0.01.

[0052] Example 3: This example is basically the same as Example 1, except that terephthalic acid, 1,4-butanediol, and concentrated sulfuric acid are added into the esterification reaction kettle in a mass ratio of 1:1.8:0.02.

[0053] Example 4: This example is basically the same as Example 1, except that the mass ratio of the esterification product, ethylene glycol, and p-toluenesulfonic acid is 1:0.1:0.01.

[0054] Example 5: This example is basically the same as Example 1, except that the mass ratio of the esterification product, ethylene glycol, and p-toluenesulfonic acid is 1:0.3:0.015.

[0055] Example 6: This example is basically the same as Example 1, except that p-toluenesulfonic acid is added into the polycondensation reactor until the pressure in the polycondensation reactor reaches 0.3 MPa and the temperature reaches 80°C.

[0056] Example 7: This example is basically the same as Example 1, except that p-toluenesulfonic acid is added into the polycondensation reactor until the pressure in the polycondensation reactor reaches 0.4 MPa and the temperature reaches 100°C.

[0057] Example 8: This example is basically the same as Example 1, except that the temperature in the polycondensation reactor increases by 25°C for every 40kPa decrease in the pressure in the polycondensation reactor.

[0058] Example 9: This example is basically the same as Example 1, except that the temperature in the polycondensation reactor increases by 30°C for every 60kPa decrease in the pressure in the polycondensation reactor.

[0059] Example 10: This example is basically the same as Example 1, except that, after the temperature in the polycondensation reactor reaches 200°C, the temperature is maintained and the addition of modified titanium dioxide is stopped, and vacuuming is continued until the pressure in the polycondensation reactor reaches 1 kPa.

[0060] Example 11: This example is basically the same as Example 1, except that, after the temperature in the polycondensation reactor reaches 240°C, the temperature is kept high and the addition of modified titanium dioxide is stopped, and vacuuming is continued until the pressure in the polycondensation reactor reaches 2kPa.

[0061] Example 12: This example is basically the same as Example 1, except that the single addition amount of modified titanium dioxide accounts for 0.05% of the total mass of the esterification product.

[0062] Example 13: This example is basically the same as Example 1, except that the single addition amount of modified titanium dioxide accounts for 0.08% of the total mass of the esterification product.

[0063] Example 14: This example is basically the same as Example 1, except that the pressure in the polycondensation reactor reaches 100 Pa and the temperature reaches 270°C.

[0064] Example 15: This example is basically the same as Example 1, except that the pressure in the polycondensation reactor reaches 200 Pa and the temperature reaches 290°C.

[0065] Example 16: This example is basically the same as Example 1, except that the mass ratio of tetrabutyl titanate, vinyl acetate, and anhydrous ethanol is 1:1:5.

[0066] Example 17: This example is basically the same as Example 1, except that the mass ratio of tetrabutyl titanate, vinyl acetate, and anhydrous ethanol is 1:2:6.

[0067] Example 18: This example is basically the same as Example 1, except that the addition rate of deionized water is 40 ml / min, and the addition of deionized water is stopped until the added amount of deionized water accounts for 10% of the total volume of the mixed solution.

[0068] Example 19: This example is basically the same as Example 1, except that the addition rate of deionized water is 80 ml / min, and the addition of deionized water is stopped until the added amount of deionized water accounts for 20% of the total volume of the mixed solution.

[0069] Example 20: This example is basically the same as Example 1, except that it is subsequently calcined at 150° C. for 2 h to obtain modified titanium dioxide.

[0070] Example 21: This example is basically the same as Example 1, except that it is subsequently calcined at 280°C for 4 hours to obtain modified titanium dioxide.

[0071] Comparative Example 1: Using Example 1 as a reference, nitrogen was not added to the polycondensation reactor. After the temperature in the polycondensation reactor reached 90°C, p-toluenesulfonic acid was added to the polycondensation reactor, and then the temperature and pressure were maintained for 25 minutes, and the modified titanium dioxide was added to the polycondensation reactor all at once.

[0072] Comparative Example 2: Using Example 1 as a reference, no modified titanium dioxide was added.

[0073] Comparative Example 3: Taking Example 1 as a reference, the modified titanium dioxide was replaced with unmodified nano titanium dioxide particles.

[0074] Comparative Example 4: Taking Example 1 as a reference, anhydrous ethanol was used instead of vinyl acetate when preparing modified titanium dioxide.

[0075] Experimental Example: In order to explore the influence of the parameters of each embodiment on the performance of the UV-resistant RCGT elastic FDY, the UV-resistant RCGT elastic FDY of each embodiment and the comparative example was tested for elongation at break. Subsequently, the UV-resistant RCGT elastic FDY prepared in each embodiment was irradiated for 42 days under an ultraviolet light source with a UVA / UVB ratio of 0.83:0.17, and the tensile strength of the UV-resistant RCGT elastic FDY before and after UV irradiation was tested. The tensile strength retention rate of the UV-resistant RCGT elastic FDY before and after UV irradiation was obtained by calculation. The specific exploration is as follows:

[0076] Experimental Example 1: Investigating the influence of esterification reaction parameters on the properties of UV-resistant RCGT elastic FDY

[0077] Using Examples 1 to 5 as experimental comparison, the UV-resistant RCGT elastic FDY properties under different esterification reaction parameters are shown in Table 1 below:

[0078] Table 1 UV-resistant RCGT elastic FDY properties under different esterification reaction parameters

[0079] Group Elongation at break Tensile strength retention rate Example 1 52.42％ 82.33％ Example 2 51.85％ 81.52％ Example 3 51.22％ 81.81％

[0080] It can be seen from the data in Table 1 that compared with Examples 1, 2, and 3, the elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY of Example 1 are both the highest. This may be because under the esterification reaction parameters of Example 1, the esterification reaction is most complete and the by-products are the least. Therefore, the esterification reaction parameters of Example 1 are optimal.

[0081] Experimental Example 2: Investigating the influence of precondensation parameters on the properties of UV-resistant RCGT elastic FDY

[0082] Using Example 1, Examples 6 to 13, and Comparative Examples 1 to 3 as experimental comparisons, the UV-resistant RCGT elastic FDY properties under different pre-condensation parameters are shown in Table 2 below:

[0083] Table 2 Anti-UV RCGT elastic FDY properties under different precondensation parameters

[0084] Group Elongation at break Tensile strength retention rate Example 1 52.42％ 82.33％ Example 4 50.45％ 81.42％ Example 5 52.12％ 80.95％ Example 6 50.74％ 81.19％ Example 7 51.42％ 81.88％ Example 8 51.48％ 81.23％ Example 9 50.88％ 80.76％ Example 10 51.19％ 81.20％ Example 11 50.52％ 80.65％ Example 12 52.69％ 79.11％ Example 13 49.24％ 83.72％ Comparative Example 1 45.24％ 79.30％ Comparative Example 2 54.16％ 60.13％ Comparative Example 3 42.13％ 77.24％

[0085] As can be seen from the data in Table 2, compared with Examples 1, 4, and 5, the elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY of Example 1 are both the highest. This may be because the mass ratio of the esterification product, ethylene glycol, and p-toluenesulfonic acid in Example 1 produces the least by-products during the pre-polycondensation reaction. Therefore, the mass ratio of the esterification product, ethylene glycol, and p-toluenesulfonic acid selected in Example 1 is optimal.

[0086] Comparing Examples 1, 6, and 7: The elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY of Example 1 are both the highest. This may be because the addition of p-toluenesulfonic acid at the temperature of Example 1 has the best catalytic effect and the most complete conversion of the esterification product. Therefore, the temperature selected for adding p-toluenesulfonic acid in Example 1 is the optimal temperature.

[0087] Comparing Examples 1, 8, and 9: The elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY of Example 1 are both the highest. This may be because under the pressure change and temperature change in the polycondensation reactor selected in Example 1, the modified titanium dioxide can be fully dispersed in the polyester and well combined with the polyester matrix. Therefore, the pressure change and temperature change in the polycondensation reactor selected in Example 1 are optimal.

[0088] Comparing Examples 1, 10, and 11: The elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY of Example 1 are both the highest. This may be because the final pressure and temperature of the polycondensation reactor selected in Example 1 allow the esterification product and ethylene glycol to fully undergo polycondensation reaction. Therefore, the final pressure and temperature of the polycondensation reactor selected in Example 1 are optimal.

[0089] Comparing Examples 1, 12, and 13: As the addition amount of modified titanium dioxide increases, the elongation at break of the UV-resistant RCGT elastic FDY decreases, and the tensile strength retention rate increases, indicating that an increase in the single addition amount of modified titanium dioxide will reduce the elasticity of the UV-resistant RCGT elastic FDY, but will improve the UV resistance of the UV-resistant RCGT elastic FDY. Therefore, the addition amount of modified titanium dioxide can be selected as needed;

[0090] Compared with Comparative Example 1, Example 1 did not charge the polycondensation reactor with nitrogen, and after all the modified titanium dioxide was added to the polycondensation reactor at once, the elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY decreased. This may be because the lack of nitrogen caused the ethylene glycol to fail to fully polymerize, and the modified titanium dioxide could not be fully dispersed in the polyester. Therefore, the modified titanium dioxide addition method selected in Example 1 is the best.

[0091] Example 1 compared with Comparative Examples 2 and 3: Without the addition of modified titanium dioxide, the elongation at break of the UV-resistant RCGT elastic FDY is increased, but the tensile strength retention rate is significantly reduced. After using unmodified nano titanium dioxide particles, the elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY are both reduced. This may be because the compatibility of unmodified titanium dioxide with the polyester matrix is ​​poor. Therefore, it is best to select modified titanium dioxide in Example 1.

[0092] Experimental Example 3: Investigating the influence of final polycondensation parameters on the properties of UV-resistant RCGT elastic FDY

[0093] Using Example 1 and Examples 14-15 as experimental comparisons, the UV-resistant RCGT elastic FDY properties under different final polycondensation parameters are shown in Table 3 below:

[0094] Table 3 Anti-UV RCGT elastic FDY properties under different final polycondensation parameters

[0095] Group Elongation at break Tensile strength retention rate Example 1 52.42％ 82.33％ Example 14 51.17％ 81.19％ Example 15 50.38％ 80.98％

[0096] It can be seen from the data in Table 3 that compared with Examples 1, 14 and 15, the elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY of Example 1 are the highest. This may be because the pre-condensation product under the final condensation parameters of Example 1 can be fully converted, so the final condensation parameters selected in Example 1 are optimal.

[0097] Experimental Example 4: Investigating the influence of modified titanium dioxide preparation parameters on the properties of UV-resistant RCGT elastic FDY

[0098] Using Example 1, Examples 16 to 21, and Comparative Example 4 as experimental comparisons, the UV-resistant RCGT elastic FDY properties under different modified titanium dioxide preparation parameters are shown in Table 4 below:

[0099] Table 4 Anti-UV RCGT elastic FDY properties under different modified titanium dioxide preparation parameters

[0100] Group Elongation at break Tensile strength retention rate Example 1 52.42％ 82.33％ Example 16 49.97％ 80.16％ Example 17 50.72％ 80.65％ Example 18 51.20％ 81.28％ Example 19 51.58％ 81.94％ Example 20 51.74％ 80.89％ Example 21 50.66％ 80.24％ Comparative Example 4 45.81％ 77.14％

[0101] It can be seen from the data in Table 4 that, compared with Examples 1, 16, and 17, the elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY of Example 1 are both the highest. This may be because the reaction between tetrabutyl titanate and vinyl acetate is the most complete under the ratio of tetrabutyl titanate, vinyl acetate, and anhydrous ethanol in Example 1. Therefore, the ratio of tetrabutyl titanate, vinyl acetate, and anhydrous ethanol selected in Example 1 is the best.

[0102] Comparing Examples 1, 18, and 19: The elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY of Example 1 are both the highest. This may be because the hydrolysis rate of tetrabutyl titanate is most suitable under the addition rate of deionized water in Example 1, so the addition rate of deionized water selected in Example 1 is optimal;

[0103] Comparing Examples 1, 20, and 21: The elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY of Example 1 are both the highest. This may be because the grains produced during the calcination of titanium dioxide under the calcination parameters of Example 1 are the most suitable, so the calcination parameters selected in Example 1 are the best;

[0104] Compared with Comparative Example 4, Example 1 shows that after replacing vinyl acetate with anhydrous ethanol, the elongation at break and the tensile strength retention rate of the UV-resistant RCGT elastic FDY both decreased. This may be due to the poor compatibility of titanium dioxide and polyester caused by the lack of vinyl acetate. Therefore, the modified titanium dioxide preparation method selected in Example 1 is the best.

Claims

1. A method for preparing UV-resistant RCGT elastic FDY, characterized in that: The following steps are involved: S1. Esterification Add terephthalic acid, 1,4-butanediol, and concentrated sulfuric acid into an esterification reaction kettle in a mass ratio of 1:1.2-1.8:0.01-0.02, heat the esterification reaction kettle until the temperature inside the esterification reaction kettle reaches 180-200° C., keep warm and stir for 2-3 hours to obtain an esterification product; S2, pre-condensation S2-1. Add the esterification product and ethylene glycol into a polycondensation reactor, stir for 10 to 15 minutes, then fill the polycondensation reactor with nitrogen and heat the polycondensation reactor until the pressure in the polycondensation reactor reaches 0.3 to 0.4 MPa and the temperature reaches 80 to 100° C., then add p-toluenesulfonic acid into the polycondensation reactor, and then maintain the temperature and pressure for 20 to 30 minutes; wherein the mass ratio of the esterification product, ethylene glycol, and p-toluenesulfonic acid is 1:0.1 to 0.3:0.01 to 0.015; S2-2, after the insulation is completed, the polycondensation reaction kettle is evacuated and heated, and the temperature in the polycondensation reaction kettle is increased by 25 to 30° C. for every 40 to 60 kPa drop in the pressure in the polycondensation reaction kettle, and the temperature is kept at this temperature and pressure for 10 to 15 minutes. During the insulation and pressure holding process, modified titanium dioxide is added to the polycondensation reaction kettle once until the temperature in the polycondensation reaction kettle reaches 200 to 240° C., then the temperature is kept and the addition of modified titanium dioxide is stopped, and the evacuation is continued until the pressure in the polycondensation reaction kettle reaches 1 to 2 kPa, and then the temperature is kept at this temperature and pressure for 1 to 2 hours to obtain a pre-condensation product; wherein, the single addition amount of modified titanium dioxide accounts for 0.05 to 0.08% of the total mass of the esterification product; S3, final polycondensation Continue to evacuate the polycondensation reactor and heat it until the pressure inside the polycondensation reactor reaches 100-200 Pa and the temperature reaches 270-290° C. After maintaining the temperature and pressure for 2-3 hours, a melt is obtained; S4, Spinning The melt is spun through a spinning machine, and then stretched, cooled, heat-set and wound in sequence to obtain UV-resistant RCGT stretch FDY.

2. The method for preparing UV-resistant RCGT elastic FDY according to claim 1, characterized in that: The preparation method of the modified titanium dioxide comprises the following steps: 1) adding tetrabutyl titanate and vinyl acetate to anhydrous ethanol, and adjusting the pH value of the anhydrous ethanol to 2-4 using dilute hydrochloric acid to obtain a mixed solution; wherein the mass ratio of tetrabutyl titanate, vinyl acetate, and anhydrous ethanol is 1:1-2:5-6; 2) stirring the mixture, and gradually adding deionized water to the mixture during the stirring process at a rate of 40 to 80 ml / min until the amount of deionized water added accounts for 10 to 20% of the total volume of the mixture. Stop adding deionized water and continue stirring for 30 to 40 minutes to obtain a mixed gel; 3) After the mixed gel is allowed to stand for 12 to 16 hours, the mixed gel is washed and dried, and then calcined at 150 to 280° C. for 2 to 4 hours to obtain modified titanium dioxide.

3. The method for preparing UV-resistant RCGT elastic FDY according to claim 2, characterized in that: The washing method is to rinse with deionized water.

4. The method for preparing UV-resistant RCGT elastic FDY according to claim 2, characterized in that: The drying temperature is 90-120° C., and the drying time is 8-10 hours.

5. The method for preparing UV-resistant RCGT elastic FDY according to claim 1, characterized in that: The spinning speed during the spinning is 900 to 1200 m / min.

6. The method for preparing UV-resistant RCGT elastic FDY according to claim 1, characterized in that: The stretching ratio during the stretching is 3 to 4 times.

7. The method for preparing UV-resistant RCGT elastic FDY according to claim 1, characterized in that: The cooling is performed by using a high-speed airflow of 15 to 20 m / s.

8. The method for preparing UV-resistant RCGT elastic FDY according to claim 1, characterized in that: The heat setting temperature is 200-220°C.