Preparation method of flame-retardant ultrahigh-elasticity polyester FDY (Fully Drawn Yarn) fiber

Abstract

The invention relates to the technical field of polyester fibers, in particular to a preparation method of flame-retardant ultrahigh-elasticity polyester FDY (fully drawn yarn) fibers, which comprises the following steps: S1, esterification: uniformly mixing terephthalic acid and ethylene glycol, adding the mixture into an esterification kettle, and carrying out esterification reaction to obtain an esterification product; s2-1, pre-polycondensation: adding the esterification product, Sb2O3 and a flame retardant into a pre-polycondensation kettle, and carrying out pre-polycondensation reaction to obtain a pre-polycondensation product; s2-2, final polycondensation: adding the pre-polycondensation product into a final polycondensation kettle to carry out final polycondensation reaction to obtain a PBT melt; s3, spinning: sequentially metering the PBT melt, spinning with a spinneret plate, cooling, oiling, stretching, sizing and winding to obtain the FDY fiber. According to the preparation method disclosed by the invention, the flame retardant and PET are copolymerized, so that the flame retardant property of the PET fiber is improved, smoke and harmful gas are less when the PET fiber is combusted, the PET fiber is more environment-friendly to use, and the manufacturing cost of the flame retardant is lower.

Description

Technical Field

[0001] The invention relates to the technical field of polyester fibers, and in particular to a method for preparing flame-retardant ultra-high elastic polyester FDY fibers. Background Art

[0002] Polyester is the trade name of polyester fiber in my country, and is an important variety of synthetic fiber. It is a fiber made from polyethylene terephthalate (PET), a fiber-forming polymer made by esterification or transesterification and polycondensation reaction of purified terephthalic acid (PTA) or dimethyl terephthalate (DMT) and ethylene glycol (EG), and is made by spinning and post-processing. Polyester fiber has many excellent properties: high strength, good dimensional stability, wear resistance, light resistance, weather resistance and chemical resistance.

[0003] Conventional polyester fibers have poor flame retardant properties. In order to improve the shortcomings of polyester in terms of easy ignition and combustion support, the existing technology uses halogen-modified polyester to prepare flame-retardant polyester fibers. This method can make polyester have a flame retardant effect, but the overall production cost is high, and the halogen-modified polyester releases more harmful gases during combustion, which will cause damage to the environment. Summary of the invention

[0004] In order to solve the above problems, the present invention provides a method for preparing flame retardant ultra-high elastic polyester FDY fiber.

[0005] The technical solution of the present invention is: a method for preparing flame retardant ultra-high elastic polyester FDY fiber, comprising the following steps:

[0006] S1. Esterification

[0007] Terephthalic acid and ethylene glycol are mixed evenly in a molar ratio of 1.0:1.9 and added into an esterification kettle for esterification reaction, and the generated water is removed during the esterification reaction until the esterification product is obtained after 40 to 50 minutes, and the temperature of the esterification reaction is 230 to 250°C;

[0008] S2, polycondensation

[0009] S2-1, precondensation

[0010] The esterification product, Sb2O3 and flame retardant are added into a pre-polycondensation kettle, and a pre-polycondensation reaction is carried out for 40 to 50 minutes under a low vacuum environment at 220 to 240° C. to obtain a pre-polycondensation product, wherein Sb2O3 accounts for 0.1 to 0.3% of the total mass of the esterification product, and the flame retardant accounts for 5 to 10% of the total mass of the esterification product;

[0011] S2-2, Final Polycondensation

[0012] The pre-polycondensation product is added into the final polycondensation kettle, and the final polycondensation reaction is carried out for 120 to 160 minutes under a high vacuum environment of 250 to 270° C. to obtain a PBT melt;

[0013] S3, Spinning

[0014] The PBT melt is sequentially metered, spun by a spinneret, cooled, oiled, stretched, shaped and wound to obtain FDY fiber.

[0015] Description: The above preparation method improves the flame retardant properties of PET fiber by esterifying the flame retardant with residual ethylene glycol and then copolymerizing with PET. The flame retardant property will not weaken with the increase of the number of washing times. When the PET fiber burns, there is less smoke and harmful gas, which is more environmentally friendly to use, and the manufacturing cost of the flame retardant is low.

[0016] Furthermore, the flame retardant comprises, by weight: 10 to 15 parts of trimethoxysilane, 8 to 12 parts of melamine phosphate, and 40 to 50 parts of dimethylformamide.

[0017] Note: When the flame retardants mentioned above are burned, they can release nitrogen to dilute the oxygen concentration in the air. The phosphorus silicon in the flame retardants can form a carbon layer during the combustion process to form a protective layer to isolate oxygen. The flame retardancy of PET can be improved through the synergistic flame retardancy of nitrogen, phosphorus and silicon.

[0018] Furthermore, the preparation method of the flame retardant comprises the following steps:

[0019] Step 1: completely dissolving melamine phosphate in dimethylformamide to obtain a mixed solution;

[0020] Step 2: heating the mixed solution to 90-110° C., stirring for 20-30 min to obtain a reactant, and gradually adding trimethoxysilane to the mixed solution during the heating process, and adding sulfuric acid to the mixed solution once every time the temperature of the mixed solution rises by 20-30° C., until the trimethoxysilane is completely added to the mixed solution, stopping the addition of sulfuric acid, and the amount of sulfuric acid added each time is 0.2-0.4% of the total mass of the current mixed solution;

[0021] Step 3: Add sodium hydroxide solution dropwise to the reactant to adjust the pH value of the reactant to neutral to obtain a flame retardant.

[0022] Description: The above preparation method generates a nitrogen-phosphorus-silicon synergistic flame retardant by reacting melamine phosphate with the silane functional group in trimethoxysilane, which can effectively isolate oxygen during the combustion process and improve the flame retardant properties of PET.

[0023] Furthermore, the temperature rising rate of the mixed solution is 5 to 15° C. / min.

[0024] Note: The above heating rate can effectively improve the efficiency of flame retardant preparation, while avoiding inadequate reaction caused by too fast heating.

[0025] Furthermore, the mass concentration of the sodium hydroxide solution is 10-15%.

[0026] Note: The above sodium hydroxide solution has a low concentration and a mild reaction, which facilitates precise control of the pH value of the reactants.

[0027] Furthermore, in step S1, the pressure of the esterification reaction is 0.3-0.5 MPa.

[0028] Note: Limiting the esterification reaction pressure can accelerate the removal of water molecules, increase the yield of the esterification reaction, and reduce by-products.

[0029] Furthermore, in step S2-1, the absolute pressure of the low vacuum environment is 2-3 kPa.

[0030] Note: Limiting the pre-condensation pressure can ensure that small molecules are effectively removed from the esterification product, and that the flame retardant fully reacts with the residual ethylene glycol in the esterification product, thereby improving the flame retardant effect.

[0031] Furthermore, in step S2-1, the absolute pressure of the high vacuum environment is 100-150Pa.

[0032] Note: Limiting the final polycondensation pressure can ensure the reaction rate of the final polycondensation reaction, accelerate the evaporation of by-products, enable the flame retardant and PET to be effectively blended, and ensure the viscosity of the PET melt.

[0033] Furthermore, in step S3, the spinning temperature is 270-290° C., and the spinning speed is 3600-3800 m / min.

[0034] Note: Limiting the spinning speed and temperature can ensure the strength and ductility of PET fiber.

[0035] The beneficial effects of the present invention are:

[0036] (1) The preparation method of the present invention improves the flame retardant properties of PET fiber by esterifying the flame retardant with residual ethylene glycol and then copolymerizing with PET. The flame retardant properties will not weaken with the increase of the number of washing times. When the PET fiber burns, there is less smoke and harmful gas, which is more environmentally friendly. In addition, the manufacturing cost of the flame retardant is low.

[0037] (2) When the flame retardant of the present invention burns, nitrogen is released to dilute the oxygen concentration in the air. The phosphorus silicon in the flame retardant can form a carbon layer during the combustion process to form a protective layer to isolate oxygen. The flame retardancy of PET is improved through the synergistic flame retardancy of nitrogen, phosphorus and silicon. DETAILED DESCRIPTION

[0038] In order to further illustrate the method adopted by the present invention and the effect achieved, the technical solution of the present invention will be clearly and completely described in combination with experiments below.

[0039] Embodiment 1: A method for preparing flame-retardant ultra-high elastic polyester FDY fiber, comprising the following steps:

[0040] S1. Esterification

[0041] Terephthalic acid and ethylene glycol were mixed evenly in a molar ratio of 1.0:1.9 and added into an esterification kettle for esterification reaction, and the generated water was removed during the esterification reaction until the esterification product was obtained after 45 minutes. The temperature of the esterification reaction was 240°C; wherein, the pressure of the esterification reaction was 0.4MPa;

[0042] S2, polycondensation

[0043] S2-1, precondensation

[0044] The esterification product, Sb2O3 and flame retardant are added into a pre-condensation reactor, and the pre-condensation reaction is carried out for 45 minutes under a low vacuum environment at 230°C to obtain a pre-condensation product, wherein Sb2O3 accounts for 0.2% of the total mass of the esterification product, and the flame retardant accounts for 8% of the total mass of the esterification product; wherein the absolute pressure of the low vacuum environment is 2.5 kPa;

[0045] S2-2, Final Polycondensation

[0046] The pre-polycondensation product was added into the final polycondensation kettle, and the final polycondensation reaction was carried out for 140 minutes under a high vacuum environment at 260° C. to obtain a PBT melt; wherein the absolute pressure of the high vacuum environment was 125 Pa;

[0047] S3, Spinning

[0048] The PBT melt is sequentially metered, spun by a spinneret, cooled, oiled, stretched, shaped and wound to obtain FDY fiber; wherein the spinning temperature is 280°C and the spinning speed is 3700 m / min;

[0049] The flame retardant comprises, by weight: 12 parts of trimethoxysilane, 10 parts of melamine phosphate, and 45 parts of dimethylformamide;

[0050] The preparation method of the flame retardant comprises the following steps:

[0051] Step 1: completely dissolving melamine phosphate in dimethylformamide to obtain a mixed solution; wherein the temperature of the mixed solution is increased at a rate of 10°C / min;

[0052] Step 2: Heat the mixed solution to 100°C and stir for 25 minutes to obtain a reactant, and gradually add trimethoxysilane to the mixed solution during the heating process, and add sulfuric acid to the mixed solution once every 25°C increase in the temperature of the mixed solution until the trimethoxysilane is completely added to the mixed solution, and then stop adding sulfuric acid, and the amount of sulfuric acid added each time is 0.3% of the total mass of the current mixed solution;

[0053] Step 3: adding sodium hydroxide solution dropwise to the reactant to adjust the pH value of the reactant to neutral, thereby obtaining a flame retardant; wherein the mass concentration of the sodium hydroxide solution is 12%.

[0054] Example 2: This example is basically the same as Example 1, except that the esterification product is obtained after 40 minutes, the temperature of the esterification reaction is 230° C., and the pressure of the esterification reaction is 0.3 MPa.

[0055] Example 3: This example is basically the same as Example 1, except that the esterification product is obtained after 50 minutes, the temperature of the esterification reaction is 250°C, and the pressure of the esterification reaction is 0.5 MPa.

[0056] Example 4: This example is basically the same as Example 1, except that the pre-polycondensation reaction is carried out at 220° C. for 40 min, and the absolute pressure of the low vacuum environment is 2 kPa.

[0057] Example 5: This example is basically the same as Example 1, except that the pre-polycondensation reaction is carried out at 240° C. for 50 min, and the absolute pressure of the low vacuum environment is 3 kPa.

[0058] Example 6: This example is basically the same as Example 1, except that Sb2O3 accounts for 0.1% of the total mass of the esterification product.

[0059] Example 7: This example is basically the same as Example 1, except that Sb2O3 accounts for 0.3% of the total mass of the esterification product.

[0060] Example 8: This example is basically the same as Example 1, except that the flame retardant accounts for 5% of the total mass of the esterification product.

[0061] Example 9: This example is basically the same as Example 1, except that the flame retardant accounts for 10% of the total mass of the esterification product.

[0062] Example 10: This example is basically the same as Example 1, except that the final polycondensation reaction is carried out at 250°C for 120 min, and the absolute pressure of the high vacuum environment is 100 Pa.

[0063] Example 11: This example is basically the same as Example 1, except that the final polycondensation reaction is carried out at 270°C for 160 min, and the absolute pressure of the high vacuum environment is 150 Pa.

[0064] Example 12: This example is basically the same as Example 1, except that the spinning temperature is 270°C and the spinning speed is 3600 m / min.

[0065] Example 13: This example is basically the same as Example 1, except that the spinning temperature is 290°C and the spinning speed is 3800 m / min.

[0066] Example 14: This example is basically the same as Example 1, except that the flame retardant comprises, by weight: 10 parts of trimethoxysilane, 8 parts of melamine phosphate, and 40 parts of dimethylformamide.

[0067] Example 15: This example is basically the same as Example 1, except that the flame retardant comprises, by weight: 15 parts of trimethoxysilane, 12 parts of melamine phosphate, and 50 parts of dimethylformamide.

[0068] Example 16: This example is basically the same as Example 1, except that the heating rate of the mixed liquid is 5°C / min.

[0069] Example 17: This example is basically the same as Example 1, except that the heating rate of the mixed liquid is 15°C / min.

[0070] Example 18: This example is basically the same as Example 1, except that the mixed liquid is heated to 90°C and stirred for 20 minutes to obtain the reactants, and trimethoxysilane is gradually added to the mixed liquid during the heating process. Sulfuric acid is added to the mixed liquid once every time the temperature of the mixed liquid increases by 20°C. After the trimethoxysilane is completely added to the mixed liquid, the addition of sulfuric acid is stopped, and the amount of sulfuric acid added each time is 0.2% of the total mass of the current mixed liquid.

[0071] Example 19: This example is basically the same as Example 1, except that the mixed liquid is heated to 110°C and stirred for 30 minutes to obtain the reactants, and trimethoxysilane is gradually added to the mixed liquid during the heating process. Sulfuric acid is added to the mixed liquid once every time the temperature of the mixed liquid increases by 30°C. After the trimethoxysilane is completely added to the mixed liquid, the addition of sulfuric acid is stopped, and the amount of sulfuric acid added each time is 0.4% of the total mass of the current mixed liquid.

[0072] Experimental Example: In order to explore the influence of various parameters on the performance of FDY fibers, the performance of the FDY fibers prepared in each embodiment was tested, and the specific exploration is as follows:

[0073] 1. Investigate the influence of esterification reaction parameters on FDY fiber properties

[0074] Using Examples 1, 2, and 3 as experimental comparisons, the FDY fiber properties under different esterification reaction parameters are shown in Table 1 below:

[0075] Table 1 FDY fiber properties under different esterification reaction parameters

[0076]

[0077]

[0078] It can be seen from the data in Table 1 that the elongation at break and the oxygen index of the FDY fiber of Example 1 are both the highest, indicating that the tensile strength and flame retardancy of the FDY fiber of Example 1 are both the best, and the esterification reaction parameters selected in Example 1 are optimal.

[0079] 2. Investigate the influence of precondensation parameters on FDY fiber properties

[0080] Using Examples 1, 4, and 5 as experimental comparisons, the FDY fiber properties under different precondensation parameters are shown in Table 2 below:

[0081] Table 2 FDY fiber properties under different precondensation parameters

[0082] Group Elongation at break (%) Oxygen index (%) Example 1 33.8 32.8 Example 4 30.2 30.7 Example 5 30.8 31.3

[0083] It can be seen from the data in Table 2 that the elongation at break and the oxygen index of the FDY fiber of Example 1 are both the highest, indicating that the tensile strength and flame retardancy of the FDY fiber of Example 1 are both the best, and the precondensation parameters selected in Example 1 are optimal.

[0084] 3. Investigate the effect of Sb2O3 addition on FDY fiber properties

[0085] Using Examples 1, 6, and 7 as experimental comparisons, the FDY fiber properties obtained under different Sb2O3 addition amounts are shown in Table 3 below:

[0086] Table 3 FDY fiber properties with different Sb2O3 addition amounts

[0087] Group Elongation at break (%) Oxygen index (%) Example 1 33.8 32.9 Example 6 30.3 31.4 Example 7 31.2 30.7

[0088] It can be seen from the data in Table 3 that the elongation at break and the oxygen index of the FDY fiber of Example 1 are both the highest, indicating that the FDY fiber of Example 1 has the best tensile properties and flame retardant properties, and the Sb2O3 addition amount selected in Example 1 is optimal.

[0089] 4. Investigate the effect of flame retardant addition on FDY fiber properties

[0090] Using Examples 1, 8, and 9 as experimental comparisons, the FDY fiber properties obtained under different addition amounts of flame retardant are shown in Table 4 below:

[0091] Table 4 FDY fiber properties at different addition amounts of flame retardant

[0092] Group Elongation at break (%) Oxygen index (%) Example 1 33.8 32.9 Example 8 32.2 29.5 Example 9 33.0 30.1

[0093] It can be seen from the data in Table 4 that the elongation at break and the oxygen index of the FDY fiber of Example 1 are both the highest, indicating that the tensile strength and flame retardancy of the FDY fiber of Example 1 are both the best, and the amount of flame retardant added selected in Example 1 is optimal.

[0094] 5. Investigate the influence of final polycondensation parameters on FDY fiber properties

[0095] Using Examples 1, 10, and 11 as experimental comparisons, the FDY fiber properties under different final polycondensation parameters are shown in Table 5 below:

[0096] Table 5 FDY fiber properties under different final polycondensation parameters

[0097] Group Elongation at break (%) Oxygen index (%) Example 1 33.8 32.9 Example 10 30.7 31.1 Embodiment 11 30.5 30.9

[0098] It can be seen from the data in Table 5 that the elongation at break and the oxygen index of the FDY fiber of Example 1 are both the highest, indicating that the tensile properties and flame retardant properties of the FDY fiber of Example 1 are both the best, and the final polycondensation parameters selected in Example 1 are optimal.

[0099] 6. Investigate the influence of spinning parameters on FDY fiber properties

[0100] Using Examples 1, 12, and 13 as experimental comparisons, the FDY fiber properties under different spinning parameters are shown in Table 6 below:

[0101] Table 6 FDY fiber properties under different spinning parameters

[0102] Group Elongation at break (%) Oxygen index (%) Example 1 33.8 32.9 Example 12 29.1 32.4 Example 13 28.7 32.2

[0103] It can be seen from the data in Table 6 that the elongation at break and the oxygen index of the FDY fiber of Example 1 are both the highest, indicating that the tensile properties and flame retardant properties of the FDY fiber of Example 1 are both the best, and the spinning parameters selected in Example 1 are optimal.

[0104] 7. Investigate the effect of flame retardant ingredients on FDY fiber properties

[0105] Examples 1, 14, and 15 were used as experimental comparisons, and Example 1 was used as a reference. The flame retardant used was a commercially available FR-104 flame retardant. The FDY fiber properties under different flame retardant compositions were shown in Table 7 below:

[0106] Table 7 FDY fiber properties under different flame retardant compositions

[0107] Group Elongation at break (%) Oxygen index (%) Example 1 33.8 32.9 Embodiment 14 32.4 31.6 Embodiment 15 31.8 31.8 Comparative Example 1 27.2 26.4

[0108] It can be seen from the data in Table 7 that compared with Examples 1, 14 and 15, the elongation at break and the oxygen index of the FDY fiber of Example 1 are the highest, indicating that the tensile properties and flame retardant properties of the FDY fiber of Example 1 are the best, and the flame retardant component selected in Example 1 is the best; compared with Comparative Example 1, the elongation at break and the oxygen index of the FDY fiber of Example 1 are higher, indicating that the flame retardant of Example 1 is better.

[0109] 8. Investigate the effect of the heating rate of the mixed liquid on the performance of FDY fiber

[0110] Using Examples 1, 16, and 17 as experimental comparisons, the FDY fiber properties obtained at different heating rates of the mixed solution are shown in Table 8 below:

[0111] Table 8 FDY fiber properties at different heating rates of the mixed solution

[0112] Group Elongation at break (%) Oxygen index (%) Example 1 33.8 32.9 Example 16 31.9 30.4 Embodiment 17 31.2 29.8

[0113] It can be seen from the data in Table 8 that the elongation at break and the oxygen index of the FDY fiber of Example 1 are both the highest, indicating that the FDY fiber of Example 1 has the best tensile properties and flame retardant properties, and the mixed solution selected in Example 1 has the best heating rate.

[0114] 9. Investigate the influence of flame retardant preparation parameters on FDY fiber properties

[0115] Examples 1, 18, and 19 were used as experimental comparisons. Example 1 was used as a reference, and sulfuric acid was added once as comparative example 2. The properties of FDY fibers prepared by flame retardants under different parameters were shown in Table 9 below:

[0116] Table 9 FDY fiber properties under different flame retardant preparation parameters

[0117]

[0118]

[0119] It can be seen from the data in Table 9 that the elongation at break and the oxygen index of the FDY fiber of Example 1 are the highest, indicating that the tensile strength and flame retardancy of the FDY fiber of Example 1 are the best, and the flame retardant preparation parameters selected in Example 1 are optimal.

Claims

1. A method for preparing flame-retardant ultra-high elastic polyester FDY fiber, It is characterized in that The following steps are involved: S1. Esterification Terephthalic acid and ethylene glycol are mixed evenly in a molar ratio of 1.0:1.9 and added into an esterification kettle for esterification reaction, and the generated water is removed during the esterification reaction until the esterification product is obtained after 40 to 50 minutes, and the temperature of the esterification reaction is 230 to 250°C; S2, polycondensation S2-1, precondensation The esterification product, Sb 2 O 3 The flame retardant is added to the precondensation reactor, and the precondensation reaction is carried out for 40 to 50 minutes under a low vacuum environment at 220 to 240° C. to obtain a precondensation product, Sb 2 O 3 The flame retardant accounts for 0.1-0.3% of the total mass of the esterification product, and the flame retardant accounts for 5-10% of the total mass of the esterification product; S2-2, Final Polycondensation The pre-polycondensation product is added into the final polycondensation kettle, and the final polycondensation reaction is carried out for 120 to 160 minutes under a high vacuum environment of 250 to 270° C. to obtain a PBT melt; S3, Spinning The PBT melt is sequentially metered, spun by a spinneret, cooled, oiled, stretched, shaped and wound to obtain FDY fiber.

2. The method for preparing a flame retardant ultra-elastic polyester FDY fiber according to claim 1, It is characterized in that The flame retardant comprises, by weight: 10 to 15 parts of trimethoxysilane, 8 to 12 parts of melamine phosphate, and 40 to 50 parts of dimethylformamide.

3. The method for preparing a flame retardant ultra-elastic polyester FDY fiber according to claim 2, It is characterized in that The preparation method of the flame retardant comprises the following steps: Step 1: completely dissolving melamine phosphate in dimethylformamide to obtain a mixed solution; Step 2: heating the mixed solution to 90-110° C., stirring for 20-30 min to obtain a reactant, and gradually adding trimethoxysilane to the mixed solution during the heating process, and adding sulfuric acid to the mixed solution once every time the temperature of the mixed solution rises by 20-30° C., until the trimethoxysilane is completely added to the mixed solution, stopping the addition of sulfuric acid, and the amount of sulfuric acid added each time is 0.2-0.4% of the total mass of the current mixed solution; Step 3: Add sodium hydroxide solution dropwise to the reactant to adjust the pH value of the reactant to neutral to obtain a flame retardant.

4. The method for preparing a flame retardant ultra-elastic polyester FDY fiber according to claim 3, It is characterized in that The temperature rise rate of the mixed solution is 5-15°C / min.

5. The method for preparing a flame retardant ultra-elastic polyester FDY fiber according to claim 3, It is characterized in that The mass concentration of the sodium hydroxide solution is 10-15%.

6. The method for preparing a flame retardant ultra-elastic polyester FDY fiber according to claim 1, It is characterized in that In step S1, the pressure of the esterification reaction is 0.3-0.5 MPa.

7. The method for preparing a flame retardant ultra-elastic polyester FDY fiber according to claim 1, It is characterized in that In step S2-1, the absolute pressure of the low vacuum environment is 2-3 kPa.

8. The method for preparing a flame retardant ultra-elastic polyester FDY fiber according to claim 1, It is characterized in that In step S2-1, the absolute pressure of the high vacuum environment is 100-150Pa.

9. The method for preparing a flame retardant ultra-elastic polyester FDY fiber according to claim 1, It is characterized in that In step S3, the spinning temperature is 270-290° C., and the spinning speed is 3600-3800 m / min.

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