Cationic dyeable polyester fiber and preparation method thereof

Abstract

The invention belongs to the technical field of cationic polyester fiber preparation, and discloses a cationic dyeable polyester fiber and a preparation method thereof. The preparation method of the cationic polyester fiber comprises the following steps: sequentially performing an esterification reaction, a pre-polycondensation reaction and a final polycondensation reaction on raw materials such as triphenyl phosphate, 5-sulfoisophthalic acid sodium salt, ethylene glycol, terephthalic acid, an antimony catalyst, expandable graphite powder and tetrabutyl titanate to prepare a cationic polyester melt; and then preparing the cationic dyeable polyester fiber through a POY-DTY process. The cationic dyeable polyester fiber prepared in the invention has both flame-retardant and cationic dyeable properties, various side reactions can be reduced by adding the compounded flame retardant and cationic dyeable assistant during the pre-polycondensation reaction or esterification reaction, and the cationic dyeable polyester fiber has more stable and remarkable flame-retardant and cationic dyeable effects.

Description

Technical Field

[0001] The present application relates to the technical field of cationic polyester fiber preparation, and in particular to a cationic dyeable polyester fiber and a preparation method thereof. Background Art

[0002] Chemical fiber is an important raw material in the textile field, among which polyester fiber accounts for 70% of the total output of chemical fiber. Improving the differentiation and functionalization level of polyester fiber is directly related to the upgrading of polyester products. Comfort modification is the development trend of differentiation and functionalization of polyester fiber, among which gloss and dyeing performance are the basis of comfortable polyester fiber products. Although polyester chemical fiber fabrics have the advantages of good hand feel, good drape and good wrinkle resistance, their disadvantages compared with cotton and linen are low moisture absorption, no water absorption, and uncomfortable wearing. Functional fibers are in short supply, and domestic textile companies that produce high-end fabrics need to import a certain amount of functional polyester filaments every year. Since polyester itself contains only carbon, hydrogen, and oxygen structures, and does not contain flame retardant groups in its molecular structure, polyester is a flammable material. Therefore, polyester fiber itself is a non-intrinsic flame retardant polymer, which produces a large amount of combustible volatile components when decomposed by heat, which is easy to burn and cause fire, limiting the wide application of polyester fiber in fields with high flame retardancy. Summary of the invention

[0003] In order to solve the above technical problems and develop a cationic dyeable polyester fiber with good flame retardancy and good dyeing stability, the present application provides a cationic dyeable polyester fiber and a preparation method thereof.

[0004] In a first aspect, the present application provides a method for preparing a cationic dyeable polyester fiber, comprising the following steps: S1, adding triphenyl phosphate, sodium 5-sulfoisophthalic acid, ethylene glycol and cobalt acetate into a reaction kettle and mixing them to carry out esterification reaction to obtain an intermediate esterification product; S2, adding terephthalic acid and antimony catalyst into the reactor to continue esterification reaction, transferring the reaction product to a pre-polycondensation reactor, adding expandable graphite powder and tetrabutyl titanate into the pre-polycondensation reactor and stirring, and carrying out pre-polycondensation reaction under the joint action of a vacuum unit to obtain a pre-polycondensation reactant; S3, transferring the pre-polycondensation reactant obtained in step S2 to a final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to perform a final polycondensation reaction, and obtaining a cationic polyester melt; S4, the cationic polyester melt obtained in step S3 is subjected to POY-DTY process, metering, extrusion, cooling, oiling and winding to obtain polyester POY fiber; the obtained polyester POY fiber is heated, stretched, twisted, shaped, oiled and wound to obtain cationic dyeable polyester fiber.

[0005] Optionally, in step S1, the weight ratio of triphenyl phosphate, 5-sodium sulfoisophthalic acid, and ethylene glycol is 2-3:1:12-18.

[0006] Optionally, in step S1, the weight ratio of triphenyl phosphate, 5-sodium sulfoisophthalate, and ethylene glycol is 2:1:14.

[0007] Optionally, the amount of cobalt acetate used is 0.1-0.3wt% of the amount of ethylene glycol used.

[0008] Optionally, the weight ratio of the terephthalic acid added in the step S2 to the ethylene glycol added in the step S1 is 3:2-3.

[0009] By adopting the above technical scheme, the present application adds triphenyl phosphate and tetrabutyl titanate before the pre-polycondensation reaction, thereby reducing the self-polymerization reaction of SIPE, increasing the solubility of SIPE in ethylene glycol, reducing the amount of ethylene glycol used, and improving the spinnability, thermal stability and filtration performance of the cationic dyeable polyester; in addition, triphenyl phosphate is used as a flame retardant in combination with expandable graphite, which further enhances the flame retardant properties of the cationic dyeable polyester fiber. During the PET polymerization process, the inorganic powder expandable graphite is uniformly dispersed in advance and added to the polyester system when the viscosity is low, and triphenyl phosphate as a compatibilizer can effectively solve the problems of transitional agglomeration and sedimentation of inorganic powders due to the high specific surface area of ​​expandable graphite, thereby improving the spinnability, thermal stability and flame retardancy of the cationic dyeable polyester.

[0010] Optionally, in step S2, the amount of expandable graphite powder added is 0.5-1.5wt% of the amount of terephthalic acid used.

[0011] Preferably, in step S2, the amount of expandable graphite powder added is 0.8-1.3 wt % of the amount of terephthalic acid used.

[0012] Optionally, in step S2, the amount of tetrabutyl titanate added is 4-8wt% of the amount of terephthalic acid used.

[0013] Optionally, in step S1, protective gas is charged into the reaction system, the esterification pressure is 0.4-0.5 MPa, the esterification temperature is 220-250° C., and the esterification time is 2-4 h.

[0014] Optionally, in step S2, during the esterification reaction, the pressure is normal pressure, the temperature is 250-270° C., and the time is 1-2 h.

[0015] Optionally, in step S2, during the pre-polycondensation reaction, the vacuum degree is 100-500 Pa, the temperature is 270-280° C., and the time is 1-2.5 h.

[0016] Optionally, in step S3, during the final polycondensation reaction, the vacuum degree is 250-350 Pa, the temperature is 280-285° C., and the time is 1-2 h.

[0017] Optionally, in step S2, the particle size of the added expandable graphite is 50-300 um.

[0018] Optionally, step S3 further includes performing viscosity increasing treatment on the prepared cationic polyester melt, including the following steps: using nitrogen as purge gas, controlling the flow rate of the purge gas to 10-60 L / h, controlling the viscosity increasing temperature to 220-250°C, the time to 20-40h, and the vacuum degree to 500-1000Pa.

[0019] Optionally, in step S3, the intrinsic viscosity of the cationic polyester melt obtained after the final polycondensation reaction is completed is 0.55-0.65 dL / g.

[0020] Optionally, in step S4, the parameters of the POY process are: spinning temperature of 288-290°C, cooling temperature of 20-25°C, network pressure of 0.30-0.35Mpa, spinning speed of 2500-2700m / min; the parameters of the DTY process are: processing speed of 600-700m / min, heating temperature of 150-170°C, stretching multiple of 1.6-1.9, and shaping overfeed rate of 2.5-3.5%.

[0021] In a second aspect, the present application provides a cationic dyeable polyester fiber, which is prepared using the above-mentioned method for preparing the cationic dyeable polyester fiber.

[0022] In summary, the present invention includes at least one of the following beneficial technical effects: 1. The method for preparing the cationically dyeable polyester fiber in the present application comprises adding triphenyl phosphate and tetrabutyl titanate and adding expandable graphite during the preparation process, wherein triphenyl phosphate is used as a flame retardant in combination with expandable graphite to enhance the flame retardant properties of the cationically dyeable polyester fiber; the cationically dyeable polyester fiber prepared in the present application has both flame retardant and cationically dyeable properties, and the addition of the compounded flame retardant and cationically dyeable auxiliary agent during the pre-polycondensation reaction or the esterification reaction can reduce the occurrence of various side reactions, and has more stable and significant flame retardant and cationically dyeable effects.

[0023] 2. The cationic polyester melt prepared in the present application has the property of halogen-free flame retardancy, and its intrinsic viscosity and melting point are similar to those of conventional PET polyester chips, and it has good spinnability and will not affect other properties of the fiber. DETAILED DESCRIPTION

[0024] The present application provides a method for preparing cationic dyeable polyester fiber, comprising the following steps: S1, adding triphenyl phosphate, sodium 5-sulfoisophthalic acid, ethylene glycol and cobalt acetate into a reaction kettle and mixing them to carry out esterification reaction to obtain an intermediate esterification product; S2, adding terephthalic acid and antimony catalyst into the reactor to continue esterification reaction, transferring the reaction product to a pre-polycondensation reactor, adding expandable graphite powder and tetrabutyl titanate into the pre-polycondensation reactor and stirring, and carrying out pre-polycondensation reaction under the joint action of a vacuum unit to obtain a pre-polycondensation reactant; S3, transferring the pre-polycondensation reactant obtained in step S2 to a final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to perform a final polycondensation reaction, and obtaining a cationic polyester melt; S4, the cationic polyester melt obtained in step S3 is subjected to POY-DTY process, metering, extrusion, cooling, oiling and winding to obtain polyester POY fiber; the obtained polyester POY fiber is heated, stretched, twisted, shaped, oiled and wound to obtain cationic dyeable polyester fiber.

[0025] The present application also provides a cationic dyeable polyester fiber prepared by the above-mentioned preparation method of the cationic dyeable polyester fiber.

[0026] The technical problem solved by the present application is that the existing cationic dyeable polyester fiber is a flammable material. When it is flame-retardant modified, its dyeing stability is easily affected, which limits the wide application of polyester fiber in fields with high flame retardancy. The present application enhances the flame retardant properties of the cationic dyeable polyester fiber by adding triphenyl phosphate and tetrabutyl titanate and adding expandable graphite during the preparation process, and using triphenyl phosphate as a flame retardant in combination with expandable graphite; the cationic dyeable polyester fiber prepared by the present application has both flame retardant and cationic dyeable properties.

[0027] The present application is further described in detail below in conjunction with specific embodiments.

[0028] Example 1 The preparation process of the cationic dyeable polyester fiber in Example 1 comprises the following steps: S1, add 2kg triphenyl phosphate, 1kg sodium 5-sulfoisophthalic acid, 14kg ethylene glycol and 0.03kg cobalt acetate into a reactor and mix, fill with nitrogen as a protective gas, carry out esterification reaction, control the pressure to 0.4MPa, the temperature to 240°C, and the reaction time to 3h to obtain an intermediate esterification product; S2, add 20kg terephthalic acid and 0.1kg ethylene glycol antimony to the reactor to continue the esterification reaction, set the temperature to 255°C, and react for 1.5h at normal pressure; transfer the reaction product to a pre-polycondensation reactor, add 0.2kg expandable graphite powder and 1kg tetrabutyl titanate to the pre-polycondensation reactor and stir, and carry out a pre-polycondensation reaction under the joint action of a vacuum unit, the vacuum degree is controlled to 400Pa, the temperature is set to 275°C, the reaction time is 1.5h, and a pre-polycondensation reactant is obtained; the average particle size of the expandable graphite powder is about 200um; S3, transferring the pre-polycondensation reactant obtained in step S2 to the final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to carry out the final polycondensation reaction, the vacuum degree is controlled to 300Pa, the temperature is set to 280°C, the reaction time is 1.5h, and a cationic polyester melt is obtained, and the intrinsic viscosity reaches about 0.62dL / g; the cationic polyester melt is subjected to viscosity-increasing treatment, nitrogen is used as the purge gas, the flow rate of the purge gas is controlled to be 50L / h, the viscosity-increasing temperature is controlled to be 240°C, the vacuum degree is controlled to be 800Pa, and the viscosity-increasing time is 25h; S4, transferring the pre-polycondensation reactant obtained in step S2 to the final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to carry out the final polycondensation reaction, the vacuum degree is controlled to be 300Pa, the temperature is set to be 280°C, and the reaction time is 1.5h, and a cationic polyester melt is obtained, and the intrinsic viscosity reaches about 0.62dL / g; the cationic polyester melt is subjected to viscosity-increasing treatment, nitrogen is used as the purge gas, the flow rate of the purge gas is controlled to be 50L / h, the viscosity-increasing temperature is controlled to be 240°C, the vacuum degree is controlled to be 800Pa, and the viscosity-increasing time is 25h; The cationic polyester melt prepared in step S3 adopts the POY-DTY process. The POY process is as follows: the cationic polyester melt is added to the screw extruder through a metering pump for melting, the circular hole multi-hole spinneret assembly is spun, the ring blow tube is used for short-distance blowing cooling, oiling, and winding to obtain polyester POY fiber, and the linear density of the polyester POY fiber is 3.22D; the DTY process is as follows: the wound polyester POY fiber is unwound and then heated, the first stage oil bath drawing, the second stage steam drawing, twisting, low temperature tension heat setting, stacking and oiling, and winding to obtain cationic dyeable polyester fiber.

[0029] Equipment parameters in POY process are as follows: The metering pump frequency is 41.00 Hz, the screw extruder temperature is: zone 1 245°C, zone 2 255°C, zone 3 265°C, zone 4 375°C, zone 5 265°C, zone 6 260°C, filter, melt pipe and box 265°C; The spinneret diameter is 220 mm, the number of holes is 2880 holes, the diameter of the spinneret micropores (circular holes) is 0.20±0.002 mm, and the aspect ratio of the spinneret micropores is 2:1; the distance from the spinneret surface to the uppermost row of blowing holes of the ring blowing tube is 40 mm; the cooling wind speed is 0.9 m / s, and the cooling temperature is 25°C; the spinneret spinning speed is 2500 m / min, the spinning temperature is 290°C, and the network pressure is 0.30 MPa.

[0030] The equipment parameters in the DTY process are as follows: The heating temperature is 150°C, the first-stage oil bath drawing is 65°C; the second-stage steam drawing is 100°C, the total drawing multiple is 1.8 times, the shaping overfeed rate is 3.1%, and the processing speed is 600m / min.

[0031] After measurement, the actual linear density of the cationic dyeable polyester fiber prepared in this embodiment is 1.12D, the linear density deviation rate is -3.2%, the breaking strength is 3.38 cN / dtex, the breaking elongation is 29.3%, and the curling rate is 11.6%.

[0032] Example 2 The preparation process of the cationic dyeable polyester fiber in Example 2 comprises the following steps: S1, add 2kg triphenyl phosphate, 1kg sodium 5-sulfoisophthalic acid, 18kg ethylene glycol and 0.03kg cobalt acetate into a reactor and mix, fill with nitrogen as a protective gas, carry out esterification reaction, control the pressure to 0.4MPa, the temperature to 240°C, and the reaction time to 3h to obtain an intermediate ester; S2, add 18kg terephthalic acid and 0.1kg ethylene glycol antimony to the reactor to continue the esterification reaction, set the temperature to 255°C, and react for 1.5h at normal pressure; transfer the reaction product to a pre-polycondensation reactor, add 0.27kg expandable graphite powder and 1.44kg tetrabutyl titanate to the pre-polycondensation reactor and stir, and carry out pre-polycondensation reaction under the joint action of a vacuum unit, the vacuum degree is controlled to 400Pa, the temperature is set to 275°C, the reaction time is 1.5h, and a pre-polycondensation reactant is obtained; the average particle size of the expandable graphite powder is about 200um; S3, transferring the pre-polycondensation reactant obtained in step S2 to the final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to carry out the final polycondensation reaction, the vacuum degree is controlled to 300Pa, the temperature is set to 280°C, the reaction time is 1.5h, and a cationic polyester melt is obtained, and the intrinsic viscosity reaches about 0.57dL / g; the cationic polyester melt is subjected to a viscosity-increasing treatment, using nitrogen as a purge gas, controlling the flow rate of the purge gas to 50L / h, controlling the viscosity-increasing temperature to 240°C, controlling the vacuum degree to 800Pa, and the viscosity-increasing time to 25h; S4, transferring the pre-polycondensation reactant obtained in step S2 to the final polycondensation reaction kettle, adjusting the vacuum unit to 300Pa, the temperature to 280°C, the reaction time to 1.5h, and the cationic polyester melt is subjected to a viscosity-increasing treatment, using nitrogen as a purge gas, controlling the flow rate of the purge gas to 50L / h, controlling the viscosity-increasing temperature to 240°C, controlling the vacuum degree to 800Pa, and the viscosity-increasing time to 25h; The cationic polyester melt prepared in step S3 adopts the POY-DTY process. The POY process is as follows: the cationic polyester melt is added to the screw extruder through a metering pump for melting, the circular hole multi-hole spinneret assembly is spun, the ring blow tube is used for short-distance blowing cooling, oiling, and winding to obtain polyester POY fiber, and the linear density of the polyester POY fiber is 3.15D; the DTY process is as follows: the wound polyester POY fiber is unwound and then heated, the first stage oil bath drawing, the second stage steam drawing, twisting, low temperature tension heat setting, stacking and oiling, and winding to obtain cationic dyeable polyester fiber.

[0033] The equipment parameters in the POY process and DTY are the same as those in Example 1.

[0034] After measurement, the actual linear density of the cationic dyeable polyester fiber prepared in this embodiment is 1.08D, the linear density deviation rate is -3.1%, the breaking strength is 3.28 cN / dtex, the breaking elongation is 28.3%, and the curling rate is 13.4%.

[0035] Example 3 The preparation process of the cationic dyeable polyester fiber in Example 3 comprises the following steps: S1, 3kg triphenyl phosphate, 1kg sodium 5-sulfoisophthalic acid, 12kg ethylene glycol and 0.03kg cobalt acetate were added to a reactor and mixed, nitrogen was charged as a protective gas, and an esterification reaction was carried out. The pressure was controlled at 0.4MPa, the temperature was controlled at 240°C, and the reaction time was 3h to obtain an intermediate esterification product; S2, add 12kg terephthalic acid and 0.1kg ethylene glycol antimony to the reactor to continue the esterification reaction, set the temperature to 255°C, and react for 1.5h at normal pressure; transfer the reaction product to a pre-polycondensation reactor, add 0.096kg expandable graphite powder and 0.48kg tetrabutyl titanate to the pre-polycondensation reactor and stir, and carry out pre-polycondensation reaction under the joint action of a vacuum unit, the vacuum degree is controlled to 400Pa, the temperature is set to 275°C, the reaction time is 1.5h, and a pre-polycondensation reactant is obtained; the average particle size of the expandable graphite powder is about 200um; S3, transferring the pre-polycondensation reactant obtained in step S2 to the final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to carry out the final polycondensation reaction, the vacuum degree is controlled to 300Pa, the temperature is set to 280°C, the reaction time is 1.5h, and a cationic polyester melt is obtained, and the intrinsic viscosity reaches about 0.58dL / g; the cationic polyester melt is subjected to viscosity-increasing treatment, nitrogen is used as the purge gas, the flow rate of the purge gas is controlled to be 50L / h, the viscosity-increasing temperature is controlled to be 240°C, the vacuum degree is controlled to be 800Pa, and the viscosity-increasing time is 25h; S4, transferring the pre-polycondensation reactant obtained in step S2 to the final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to carry out the final polycondensation reaction, the vacuum degree is controlled to be 300Pa, the temperature is set to be 280°C, and the reaction time is 1.5h, and a cationic polyester melt is obtained, and the intrinsic viscosity reaches about 0.58dL / g; the cationic polyester melt is subjected to viscosity-increasing treatment, nitrogen is used as the purge gas, the flow rate of the purge gas is controlled to be 50L / h, the viscosity-increasing temperature is controlled to be 240°C, the vacuum degree is controlled to be 800Pa, and the viscosity-increasing time is 25h; The cationic polyester melt prepared in step S3 adopts the POY-DTY process. The POY process is as follows: the cationic polyester melt is added to the screw extruder through a metering pump for melting, the circular hole multi-hole spinneret assembly is spun, the ring blow tube is used for short-distance blowing cooling, oiling, and winding to obtain polyester POY fiber, and the linear density of the polyester POY fiber is 3.26D; the DTY process is as follows: the wound polyester POY fiber is unwound and then heated, the first stage oil bath drawing, the second stage steam drawing, twisting, low temperature tension heat setting, stacking and oiling, and winding to obtain cationic dyeable polyester fiber.

[0036] The equipment parameters in the POY process and DTY are the same as those in Example 1.

[0037] After measurement, the actual linear density of the cationic dyeable polyester fiber prepared in this embodiment is 1.18D, the linear density deviation rate is -4.5%, the breaking strength is 3.14 cN / dtex, the breaking elongation is 25.1%, and the curling rate is 12.8%.

[0038] Example 4 The preparation process of the cationic dyeable polyester fiber in Example 4 comprises the following steps: S1, add 2kg triphenyl phosphate, 1kg sodium 5-sulfoisophthalic acid, 14kg ethylene glycol and 0.03kg cobalt acetate into a reactor and mix, fill with nitrogen as a protective gas, carry out esterification reaction, control the pressure to 0.4MPa, the temperature to 220°C, and the reaction time to 3h to obtain an intermediate ester; S2, add 20kg terephthalic acid and 0.1kg ethylene glycol antimony to the reactor to continue the esterification reaction, set the temperature to 250°C, and react for 1.5h at normal pressure; transfer the reaction product to a pre-polycondensation reactor, add 0.2kg expandable graphite powder and 1kg tetrabutyl titanate to the pre-polycondensation reactor and stir, and carry out a pre-polycondensation reaction under the joint action of a vacuum unit, the vacuum degree is controlled to 400Pa, the temperature is set to 270°C, the reaction time is 1.5h, and a pre-polycondensation reactant is obtained; the average particle size of the expandable graphite powder is about 200um; S3, transferring the pre-polycondensation reactant obtained in step S2 to the final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to carry out the final polycondensation reaction, the vacuum degree is controlled to 300Pa, the temperature is set to 280°C, the reaction time is 1.5h, and a cationic polyester melt is obtained, and the intrinsic viscosity reaches about 0.62dL / g; the cationic polyester melt is subjected to viscosity-increasing treatment, nitrogen is used as the purge gas, the flow rate of the purge gas is controlled to be 50L / h, the viscosity-increasing temperature is controlled to be 220°C, the vacuum degree is controlled to be 800Pa, and the viscosity-increasing time is 25h; S4, transferring the pre-polycondensation reactant obtained in step S2 to the final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to carry out the final polycondensation reaction, the vacuum degree is controlled to be 300Pa, the temperature is set to be 280°C, and the reaction time is 1.5h, and a cationic polyester melt is obtained, and the intrinsic viscosity reaches about 0.62dL / g; the cationic polyester melt is subjected to viscosity-increasing treatment, nitrogen is used as the purge gas, the flow rate of the purge gas is controlled to be 50L / h, the viscosity-increasing temperature is controlled to be 220°C, the vacuum degree is controlled to be 800Pa, and the viscosity-increasing time is 25h; The cationic polyester melt prepared in step S3 adopts the POY-DTY process. The POY process is as follows: the cationic polyester melt is added to the screw extruder through a metering pump for melting, the circular hole multi-hole spinneret assembly is spun, the ring blow tube is used for short-distance blowing cooling, oiling, and winding to obtain polyester POY fiber, and the linear density of the polyester POY fiber is 3.20D; the DTY process is as follows: the wound polyester POY fiber is unwound and then heated, the first stage oil bath drawing, the second stage steam drawing, twisting, low temperature tension heat setting, stacking and oiling, and winding to obtain cationic dyeable polyester fiber.

[0039] After measurement, the actual linear density of the cationic dyeable polyester fiber prepared in this embodiment is 1.24D, the linear density deviation rate is 2.5%, the breaking strength is 3.53 cN / dtex, the breaking elongation is 25.5%, and the curling rate is 11.4%.

[0040] Example 5 The preparation process of the cationic dyeable polyester fiber in Example 5 comprises the following steps: S1, add 2kg triphenyl phosphate, 1kg sodium 5-sulfoisophthalic acid, 14kg ethylene glycol and 0.03kg cobalt acetate into a reactor and mix, fill with nitrogen as a protective gas, carry out esterification reaction, control the pressure to 0.4MPa, the temperature to 250°C, and the reaction time to 3h to obtain an intermediate ester; S2, add 20kg terephthalic acid and 0.1kg ethylene glycol antimony to the reactor to continue the esterification reaction, set the temperature to 270°C, and react for 1.5h at normal pressure; transfer the reaction product to a pre-polycondensation reactor, add 0.2kg expandable graphite powder and 1kg tetrabutyl titanate to the pre-polycondensation reactor and stir, and carry out a pre-polycondensation reaction under the joint action of a vacuum unit, the vacuum degree is controlled to 400Pa, the temperature is set to 280°C, the reaction time is 1.5h, and a pre-polycondensation reactant is obtained; the average particle size of the expandable graphite powder is about 200um; S3, transferring the pre-polycondensation reactant obtained in step S2 to the final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to carry out the final polycondensation reaction, the vacuum degree is controlled to 300Pa, the temperature is set to 285°C, the reaction time is 1.5h, and a cationic polyester melt is obtained, and the intrinsic viscosity reaches about 0.64dL / g; the cationic polyester melt is subjected to viscosity-increasing treatment, nitrogen is used as the purge gas, the flow rate of the purge gas is controlled to be 50L / h, the viscosity-increasing temperature is controlled to be 250°C, the vacuum degree is controlled to be 800Pa, and the viscosity-increasing time is 25h; S4, transferring the pre-polycondensation reactant obtained in step S2 to the final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to carry out the final polycondensation reaction, the vacuum degree is controlled to be 300Pa, the temperature is set to be 285°C, and the reaction time is 1.5h, and a cationic polyester melt is obtained, and the intrinsic viscosity reaches about 0.64dL / g; the cationic polyester melt is subjected to viscosity-increasing treatment, nitrogen is used as the purge gas, the flow rate of the purge gas is controlled to be 50L / h, the viscosity-increasing temperature is controlled to be 250°C, the vacuum degree is controlled to be 800Pa, and the viscosity-increasing time is 25h; The cationic polyester melt prepared in step S3 adopts the POY-DTY process. The POY process is as follows: the cationic polyester melt is added to the screw extruder through a metering pump for melting, the circular hole multi-hole spinneret assembly is spun, the ring blow tube is used for short-distance blowing cooling, oiling, and winding to obtain polyester POY fiber, and the linear density of the polyester POY fiber is 3.36D; the DTY process is as follows: the wound polyester POY fiber is unwound and then heated, the first stage oil bath drawing, the second stage steam drawing, twisting, low temperature tension heat setting, stacking and oiling, and winding to obtain cationic dyeable polyester fiber.

[0041] After measurement, the actual linear density of the cationic dyeable polyester fiber prepared in this embodiment is 1.24D, the linear density deviation rate is 2.5%, the breaking strength is 3.53 cN / dtex, the breaking elongation is 22.5%, and the curling rate is 11.4%.

[0042] Comparative Example 1 Comparative Example 1 is based on Example 1, except that: during the preparation of the cationic dyeable polyester fiber in Comparative Example 1, expandable graphite powder is not added in step S2.

[0043] Comparative Example 2 Comparative Example 2 is based on Example 1, except that: in the preparation process of the cationic dyeable polyester fiber in Comparative Example 2, no triphenyl phosphate is added in step S1.

[0044] Performance Testing 1. First, the cationic dyeable polyester fibers obtained in Examples 1-5 and Comparative Examples 1-2 were immersed in a 5wt% CaCl2 solution, with a bath ratio of 1:10, an immersion temperature of 90°C, and a heat preservation time of 60min; polyphenol dye pomegranate was used for dyeing, with a bath ratio of 1:10, a dye amount of 5wt% of the fiber amount, acetic acid as an auxiliary agent, an amount of 0.5ml / l, a treatment temperature of 70°C, a treatment time of 40min, and dyeing was completed; the levelness, dye uptake and water fastness were measured, and the measurement results are shown in Table 1.

[0045] 2. Determine the limiting oxygen index LOI (%) of the cationic dyeable polyester fibers obtained in Examples 1-5 and Comparative Examples 1-2.

[0046] Table 1 By analyzing the data in Table 1, it can be obtained that the cationic dyeable polyester fiber prepared in the present application has both flame retardant and cationic dyeable properties. The addition of a compounded flame retardant and a cationic dyeable auxiliary during the pre-polycondensation reaction or the esterification reaction can reduce the occurrence of various side reactions, and has a more stable and significant flame retardant and cationic dyeable effect.

[0047] The above are all preferred embodiments of the present application, and the protection scope of the present application is not limited thereto. Therefore, any equivalent changes made according to the structure, shape, and principle of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a cationic dyeable polyester fiber, characterized in that: The following steps are involved: S1, adding triphenyl phosphate, sodium 5-sulfoisophthalate, ethylene glycol and cobalt acetate into a reaction kettle and mixing them to carry out esterification reaction to obtain an intermediate esterification product; S2, adding terephthalic acid and antimony catalyst into the reactor to continue esterification reaction, transferring the reaction product to a pre-polycondensation reactor, adding expandable graphite powder and tetrabutyl titanate into the pre-polycondensation reactor and stirring, and carrying out pre-polycondensation reaction under the joint action of a vacuum unit to obtain a pre-polycondensation reactant; S3, transferring the pre-polycondensation reactant obtained in step S2 to a final polycondensation reaction kettle, adjusting the vacuum unit to increase the vacuum degree of the reaction system to perform a final polycondensation reaction, and obtaining a cationic polyester melt; S4, the cationic polyester melt obtained in step S3 is subjected to POY-DTY process, metering, extrusion, cooling, oiling and winding to obtain polyester POY fiber; the obtained polyester POY fiber is heated, stretched, twisted, shaped, oiled and wound to obtain cationic dyeable polyester fiber.

2. The method for preparing cationic dyeable polyester fiber according to claim 1, characterized in that: In the step S1, the weight ratio of triphenyl phosphate, 5-sodium sulfoisophthalate and ethylene glycol is 2-3:1:12-18; and the amount of cobalt acetate used is 0.1-0.3wt% of the amount of ethylene glycol used.

3. The method for preparing a cationic dyeable polyester fiber according to claim 1, characterized in that: The weight ratio of the terephthalic acid added in the step S2 to the ethylene glycol added in the step S1 is 3:2-3.

4. The method for preparing a cationic dyeable polyester fiber according to claim 1, characterized in that: In step S2, the amount of expandable graphite powder added is 0.5-1.5wt% of the amount of terephthalic acid used, The amount of tetrabutyl titanate added is 4-8wt% of the amount of terephthalic acid used.

5. The method for preparing cationic dyeable polyester fiber according to claim 1, characterized in that: In the step S1, protective gas is charged into the reaction system, the esterification pressure is 0.4-0.5MPa, the esterification temperature is 220-250°C, and the esterification time is 2-4h; in the step S2, the pressure during the esterification reaction is normal pressure, the temperature is 250-270°C, and the time is 1-2h; in the step S2, during the pre-polycondensation reaction, the vacuum degree is 100-500Pa, the temperature is 270-280°C, and the time is 1-2.5h; in the step S3, during the final polycondensation reaction, the vacuum degree is 250-350Pa, the temperature is 280-285°C, and the time is 1-2h.

6. The method for preparing cationic dyeable polyester fiber according to claim 1, characterized in that: In the step S2, the particle size of the added expandable graphite is 50-300 um.

7. The method for preparing cationic dyeable polyester fiber according to claim 1, characterized in that: The step S3 also includes a viscosity-increasing treatment of the prepared cationic polyester melt, including the following steps: using nitrogen as the purge gas, controlling the flow rate of the purge gas to 10-60 L / h, controlling the viscosity-increasing temperature to 220-250° C., the time to 20-40 h, and the vacuum degree to 500-1000 Pa.

8. The method for preparing cationic dyeable polyester fiber according to claim 1, characterized in that: In the step S3, after the final polycondensation reaction is completed, the intrinsic viscosity of the cationic polyester melt obtained is 0.55-0.65 dL / g.

9. The method for preparing cationic dyeable polyester fiber according to claim 1, characterized in that: In step S4, the parameters of the POY process are: cooling temperature of 20-25°C, network pressure of 0.30-0.35Mpa, spinning speed of 2500-2700m / min; the parameters of the DTY process are: processing speed of 600-700m / min, heating temperature of 150-170°C, stretching multiple of 1.6-1.9, and shaping overfeed rate of 2.5-3.5%.

10. A cationic dyeable polyester fiber, characterized in that: The cationic dyeable polyester fiber is prepared by the preparation method of any one of claims 1 to 8.

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