Cationic polyester fiber and preparation method thereof

Abstract

The invention discloses a cationic polyester fiber, the cationic polyester comprises a terephthalic acid chain segment, an ethylene glycol chain segment, a 1, 2-octylene glycol chain segment and an isophthalic acid-5-sodium sulfonate chain segment, and the molar content of the 1, 2-octylene glycol in the cationic polyester is 8.5-10.0%. The invention also aims to disclose a preparation method of the cationic polyester fiber. The preparation method comprises the following steps: preparing the cationic polyester; the cationic polyester is melted to obtain a cationic polyester melt, the cationic polyester melt is granulated to obtain cationic polyester chips, and the cationic polyester chips are metered, extruded by a spinneret plate, cooled, oiled and wound to obtain POY (pre-oriented yarn); the POY is subjected to yarn guiding, heating stretching, twisting, heat setting and winding, DTY is obtained, and the cationic polyester fiber is obtained. According to the preparation method, the influence on the thermal performance and crystallization performance of the cationic polyester is reduced while the viscosity of the cationic polyester melt is reduced, the quality of the cationic polyester is improved, and the spinnability of the cationic polyester is improved.

Description

Technical Field

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

[0002] Polyethylene terephthalate (PET) has the disadvantages of poor hygroscopicity and dyeing performance, easy accumulation of static electricity, and easy fuzzing. Sulfonate is usually used as a modifier to modify it into a modified polyester (CDP) that can be dyed with cationic dyes. Sodium 5-sulfonate of dimethyl isophthalate (SIPM, commonly known as the third monomer) and ethylene glycol (EG) are subjected to an ester exchange reaction to prepare a sodium 5-sulfonate of ethylene isophthalate (SIPE) solution, which is then copolymerized with ethylene terephthalate (BHET). Sulfonic acid groups are introduced into the PET molecular chain after copolymerization to prepare a cationic dye-dyeable polyester (CDP). Conventional polyesters are difficult to dye because the macromolecular segments belong to rigid segments, and the molecules inside the fiber are arranged neatly and tightly, so it is difficult for dyes to enter the fiber. At the same time, since there are no functional groups that can bind dyes on the molecular chains of conventional polyesters, the color fastness after dyeing is low and it is easy to fade. Cationic dye-dyeable polyester has greatly improved the dyeing properties of polyester fibers by introducing sodium 5-sulfonate isophthalic acid into the copolymer molecular chain. Dyeing with cationic dyes produces fabrics with bright colors and high dye exhaustion rates, which greatly reduces the discharge of printing and dyeing wastewater. It is one of the main methods to improve the dyeing properties of polyester in recent years.

[0003] After SIPE is introduced into the polyethylene glycol ester macromolecule, the polar group sulfonic acid group increases the intermolecular force, and the relative movement of the molecular chain is hindered, resulting in excessive dynamic viscosity of cationic dye-dyable polyester. It is more difficult to remove small molecules during the polycondensation process, which makes the molecular weight of cationic dye-dyable polyester low and the molecular weight distribution wide, requiring a higher spinning temperature. However, too high a spinning temperature is prone to thermal degradation, and this contradiction affects the spinnability of cationic polyester. The low molecular weight also makes the mechanical properties of cationic DTY fiber lower than those of conventional polyester fiber, restricting the application of cationic DTY fiber.

[0004] Cationic polyester changes the orderly arrangement of polyester molecular chains due to sodium 5-sulfoisophthalate, and at the same time, the presence of the side group -SO3Na in the molecular chain produces a large steric hindrance effect. Therefore, after the introduction of sodium 5-sulfoisophthalate, the crystallization properties of polyester have changed greatly. The existing technology has a great impact on the thermal properties and crystallization properties of cationic polyester while reducing the melt viscosity, resulting in poor product quality. How to reduce the impact on its thermal properties and crystallization properties while reducing the melt viscosity of cationic polyester is of great significance to improving the quality of cationic polyester and improving its spinnability. Therefore, a new technical solution is urgently needed to solve at least one of the above technical problems. Summary of the invention

[0005] In view of the above-mentioned deficiencies, one object of the present invention is to provide a cationic polyester fiber with better spinnability and better mechanical properties. Another object of the present invention is to provide a method for preparing a cationic polyester fiber, which introduces a 1,2-octanediol chain segment. The addition of the 1,2-octanediol chain segment reduces the flow resistance caused by the relative movement between molecules, reduces the viscous flow activation energy, and makes shear flow easier. The shear flow becomes easier, which is manifested as a further decrease in viscosity, which is conducive to the release of small molecules in polycondensation, and further increases the molecular weight of polyester. While reducing the melt viscosity of the cationic polyester, it reduces the impact on its thermal properties and crystallization properties, improves the quality of the cationic polyester, and improves its spinnability.

[0006] In order to achieve the above technical objectives and meet the above technical requirements, the technical solution adopted by the present invention is: A cationic polyester fiber, characterized in that the cationic polyester comprises a terephthalic acid segment, an ethylene glycol segment, a 1,2-octanediol segment and a sodium 5-sulfonate isophthalic acid segment, and the molar content of the 1,2-octanediol in the cationic polyester is 8.5-10.0%.

[0007] As a preferred technical solution, the molar content of 5-sodium sulfoisophthalate in the cationic polyester is 1.5-2.0%.

[0008] The present invention also provides a method for preparing cationic polyester fiber, which is characterized by comprising the following steps: preparing the cationic polyester; The cationic polyester is melted to obtain a cationic polyester melt, the cationic polyester melt is pelletized to obtain a cationic polyester slice, and the cationic polyester slice is metered, spinneret extruded, cooled, oiled and wound to obtain a POY yarn; The POY yarn is guided, heated and stretched, twisted, heat-set and wound to obtain DTY yarn, namely the cationic polyester fiber.

[0009] As a preferred technical solution, when the shear rate of the cationic polyester melt is 1000 / s-3000 / s, its viscosity activation energy is 75.4-62.3 kJ / mol, and the intrinsic viscosity of the cationic polyester melt is 0.62-0.65 dL / g.

[0010] As a preferred technical solution, the spinning temperature for preparing the POY yarn is 280-285°C, the cooling temperature is 20-22°C, and the winding speed is 3200-3600 m / min.

[0011] As a preferred technical solution, the spinning speed for preparing the DTY yarn is 500-700 m / min, the shaping overfeed rate is 3.5-5.5%, the winding overfeed rate is 2.5-5.0%, the first hot box temperature is 180-220°C, the second hot box temperature is 150-180°C, and the stretching ratio is 1.5-1.7.

[0012] As a preferred technical solution, the specific steps for preparing the cationic polyester are as follows: Terephthalic acid, ethylene glycol and 1,2-octanediol are prepared into slurry, and a catalyst, a matting agent and a stabilizer are added and mixed evenly, and then the mixture is pressurized in a nitrogen atmosphere for esterification reaction, and the pressurization pressure is 0.3MPa, and the temperature of the esterification reaction is 250-260°C. When the amount of water distilled in the esterification reaction reaches more than 95% of the theoretical value, the esterification reaction ends. After the esterification reaction, sodium 5-sulfonate of ethylene glycol isophthalate is added and stirred for 25-30 minutes; The polycondensation reaction in the low vacuum stage is started under negative pressure conditions. The pressure in this stage is reduced to below 500 Pa absolute pressure within 30-50 minutes. The reaction temperature is 260-270° C. and the reaction time is 30-50 minutes. Then the vacuum is continued to be drawn to carry out the polycondensation reaction in the high vacuum stage. In this stage, the reaction pressure is further reduced to below 80 Pa absolute pressure. The reaction temperature is 275-280° C. and the reaction time is 50-90 minutes to obtain the cationic polyester.

[0013] As a preferred technical solution, the molar ratio of terephthalic acid, ethylene glycol, and 1,2-octanediol is 1:(1.2-1.4):(0.085-0.10).

[0014] As a preferred technical solution, the amount of the catalyst added is 0.015-0.020% by weight of terephthalic acid, the amount of the matting agent added is 0.20-0.25% by weight of terephthalic acid, and the amount of the stabilizer added is 0.01-0.03% by weight of terephthalic acid; The catalyst is one of antimony trioxide, ethylene glycol antimony or antimony acetate, the matting agent is titanium dioxide, and the stabilizer is one of triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.

[0015] As a preferred technical solution, the cationic polyester fiber has a monofilament fineness of 0.6-1.2 dtex, a breaking strength ≥3.3 cN / dtex, an elongation at break of 25.0±3.0%, a linear density deviation rate ≤1.30%, a breaking strength CV value ≤6.00%, a breaking elongation CV value ≤8.0%, a boiling water shrinkage rate of 4.0±0.5%, a curl stability ≥75%, and a curl shrinkage rate of 8.0±1.0%.

[0016] Compared with the traditional technical solution, the beneficial effects of the present invention are: The preparation method of the present invention introduces 1,2-octanediol chain segments. The addition of the 1,2-octanediol chain segments reduces the flow resistance caused by the relative movement between molecules, reduces the viscous flow activation energy, and facilitates shear flow, which is manifested in that the viscosity is further reduced, which is beneficial to the release of small molecules in polycondensation, further improves the molecular weight of the polyester, reduces the influence on the thermal properties and crystallization properties of the cationic polyester while reducing the melt viscosity of the cationic polyester, improves the quality of the cationic polyester, and improves its spinnability. DETAILED DESCRIPTION

[0017] An embodiment of the present invention provides a cationic polyester fiber, wherein the cationic polyester includes a terephthalic acid segment, an ethylene glycol segment, an 1,2-octanediol segment and a sodium 5-sulfonate isophthalic acid segment, and the molar content of the 1,2-octanediol in the cationic polyester is 8.5-10.0%.

[0018] After the introduction of sodium isophthalate-5-sulfonate into the polyethylene glycol macromolecule, the polar group sulfonic acid group increases the intermolecular force and hinders the relative movement of the molecular chain, resulting in a greatly enhanced attraction between the molecular chains in the copolyester, increased steric hindrance of chain segment movement, and thus increased spatial transition energy of the chain segment, which is manifested as viscous flow activation energy (Eη). The dynamic viscosity of the cationic polyester is too large, and it is more difficult to remove small molecules during the polycondensation process, resulting in a low molecular weight of the cationic polyester and a wide molecular weight distribution. The mechanical properties of cationic polyester fibers are lower than those of conventional polyester fibers, which restricts the application of cationic polyester fibers.

[0019] Viscous flow activation energy (Eη) is a measure of the energy barrier that needs to be overcome for a polymer melt to produce viscous flow. When the molecular chain has good flexibility, the barrier to intrachain rotation is low and the flow unit segment is short. According to the segmented mechanism of polymer flow, the holes required for the flow of flexible molecular chains are small, and the activation energy of flow is also low, so flow can occur at a lower temperature. On the contrary, the greater the molecular rigidity, the higher the temperature required for flow, which requires a higher spinning temperature. However, too high a spinning temperature is very likely to cause thermal degradation. This contradiction affects the spinnability of cationic polyesters.

[0020] The isophenylsulfonic acid group is introduced into the cationic polyester. Due to the polar effect and steric hindrance of its side group, the tightly packed crystalline structure of the original conventional polyester macromolecular chain is destroyed, making it difficult for the macromolecular chain segments combined with dimethyl isophthalate-5-sodium sulfonate to be embedded in the crystal region during the cold crystallization process, reducing the cold crystallization ability and the degree of crystallinity, which has an adverse effect on the mechanical properties of the polyester fiber.

[0021] The present invention introduces 1,2-octanediol when preparing the cationic polyester. The 1,2-octanediol side chain has a certain length and is flexible, and can be arranged in a regular lattice as required, without reducing the cold crystallization ability. The addition of the 1,2-octanediol side chain reduces the flow resistance caused by the relative movement between molecules, reduces the viscous flow activation energy, and makes the shear flow easier, which is manifested as a further decrease in viscosity, which is beneficial to the release of small molecules in polycondensation and further increases the molecular weight of the polyester. When the molar content of 1,2-octanediol in the cationic polyester is 8.5-10.0%, the cationic polyester fiber has good spinnability and excellent mechanical properties.

[0022] In some embodiments, the molar content of 5-sodium sulfoisophthalate in the cationic polyester is 1.5-2.0%. When the molar content of 5-sodium sulfoisophthalate in the cationic polyester is less than 1.5%, the dyeability of the cationic polyester will be reduced. When the molar content of 5-sodium sulfoisophthalate in the cationic polyester is greater than 2.0%, the dynamic viscosity of the cationic polyester is too large, resulting in poor spinnability of the cationic polyester.

[0023] The present invention also provides a method for preparing cationic polyester fiber, which is characterized by comprising the following steps: preparing the cationic polyester; The cationic polyester is melted to obtain a cationic polyester melt, the cationic polyester melt is pelletized to obtain a cationic polyester slice, and the cationic polyester slice is metered, spinneret extruded, cooled, oiled and wound to obtain a POY yarn; The POY yarn is guided, heated and stretched, twisted, heat-set and wound to obtain DTY yarn, namely the cationic polyester fiber.

[0024] In some embodiments, when the shear rate of the cationic polyester melt is 1000 / s-3000 / s, its viscosity flow activation energy is 75.4-62.3 kJ / mol, the intrinsic viscosity of the cationic polyester melt is 0.62-0.65 dL / g, the viscosity flow activation energy is reasonable, the dynamic viscosity is appropriate, the viscosity flow activation energy is low, and the fluidity is good, which is conducive to filtration.

[0025] In some embodiments, the spinning temperature for preparing the POY yarn is 280-285°C, the cooling temperature is 20-22°C, the winding speed is 3200-3600m / min, the spinning speed for preparing the DTY yarn is 500-700m / min, the shaping overfeed rate is 3.5-5.5%, the winding overfeed rate is 2.5-5.0%, the first hot box temperature is 180-220°C, the second hot box temperature is 150-180°C, the stretch ratio is 1.5-1.7, and the spinning temperature is the cationic The temperature of the polyester chips when they are extruded from the spinneret is cooled by ring blowing. After cooling, they are oiled by an oil nozzle. After POY yarn is prepared, DTY yarn is processed. The POY yarn is passed through the guide wire, the first roller, the first hot box heating, the cooling plate, the second roller, the twister, the third roller, the second hot box, oiling, and winding. The first hot box heats the filament bundle, and the cooling plate reduces the surface temperature of the filament bundle to prevent adhesion. The speed between the first roller and the second roller is stretched, the twister twists the filament bundle, and the second hot box heats the filament bundle. The winding speed is the spinning speed.

[0026] In some embodiments, the specific steps of preparing the cationic polyester are as follows: Terephthalic acid, ethylene glycol and 1,2-octanediol are prepared into slurry, and a catalyst, a matting agent and a stabilizer are added and mixed evenly, and then the mixture is pressurized in a nitrogen atmosphere for esterification reaction, and the pressurization pressure is 0.3MPa, and the temperature of the esterification reaction is 250-260℃. When the amount of water distilled in the esterification reaction reaches more than 95% of the theoretical value, the esterification reaction ends. After the esterification reaction, sodium 5-sulfonate of ethylene glycol isophthalate is added and stirred for 25-30min. The molar ratio of terephthalic acid, ethylene glycol and 1,2-octanediol is 1: (1.2-1.4): (0.085-0.10). Ethylene glycol is excessive during the reaction, and the excess ethylene glycol is extracted after the reaction is completed. The polycondensation reaction in the low vacuum stage is started under negative pressure conditions. The pressure in this stage is reduced to below 500 Pa absolute pressure within 30-50 minutes. The reaction temperature is 260-270° C. and the reaction time is 30-50 minutes. Then the vacuum is continued to be drawn to carry out the polycondensation reaction in the high vacuum stage. In this stage, the reaction pressure is further reduced to below 80 Pa absolute pressure. The reaction temperature is 275-280° C. and the reaction time is 50-90 minutes to obtain the cationic polyester.

[0027] In some embodiments, the catalyst is added in an amount of 0.015-0.020% by weight of terephthalic acid, the matting agent is added in an amount of 0.20-0.25% by weight of terephthalic acid, and the stabilizer is added in an amount of 0.01-0.03% by weight of terephthalic acid; The catalyst is one of antimony trioxide, ethylene glycol antimony or antimony acetate, the matting agent is titanium dioxide, and the stabilizer is one of triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.

[0028] In some embodiments, the cationic polyester fiber has a single filament fineness of 0.6-1.2 dtex, a breaking strength ≥3.3 cN / dtex, an elongation at break of 25.0±3.0%, a linear density deviation rate ≤1.30%, a breaking strength CV value ≤6.00%, a breaking elongation CV value ≤8.0%, a boiling water shrinkage rate of 4.0±0.5%, a curl stability ≥75%, and a curl shrinkage rate of 8.0±1.0%. Example

[0029] A cationic polyester fiber, the cationic polyester comprising a terephthalic acid segment, an ethylene glycol segment, an 1,2-octanediol segment and a 5-sodium sulfoisophthalic acid segment, the molar content of the 1,2-octanediol in the cationic polyester is 8.5%, and the molar content of the 5-sodium sulfoisophthalic acid in the cationic polyester is 1.5%.

[0030] A method for preparing a cationic polyester fiber comprises the following steps: preparing the cationic polyester; The cationic polyester is melted to obtain a cationic polyester melt, the cationic polyester melt is pelletized to obtain a cationic polyester slice, and the cationic polyester slice is metered, spinneret extruded, cooled, oiled and wound to obtain a POY yarn; The POY yarn is passed through a guide yarn, a first roller, a first hot box for heating, a cooling plate, a second roller, a twister, a third roller, a second hot box, oiling, and winding to obtain a DTY yarn, namely the cationic polyester fiber.

[0031] When the shear rate of the cationic polyester melt is 1000 / s, the viscosity activation energy thereof is 75.4 kJ / mol, and the intrinsic viscosity of the cationic polyester melt is 0.62 dL / g.

[0032] The spinning temperature for preparing the POY yarn is 280° C., the cooling temperature is 20° C., and the winding speed is 3200 m / min.

[0033] The spinning speed for preparing the DTY yarn is 500 m / min, the shaping overfeed rate is 3.5%, the winding overfeed rate is 2.5%, the first hot box temperature is 180° C., the second hot box temperature is 150° C., and the stretching ratio is 1.5.

[0034] The specific steps for preparing the cationic polyester are as follows: Terephthalic acid, ethylene glycol and 1,2-octanediol are prepared into slurry, and a catalyst, a matting agent and a stabilizer are added and mixed evenly, and then the mixture is pressurized in a nitrogen atmosphere for esterification reaction, and the pressurization pressure is 0.3 MPa, and the temperature of the esterification reaction is 250°C. When the amount of water distilled in the esterification reaction reaches more than 95% of the theoretical value, the esterification reaction ends. After the esterification reaction, sodium ethylene glycol 5-sulfonate is added and stirred for 25 minutes; The polycondensation reaction in the low vacuum stage is started under negative pressure conditions. The pressure in this stage is reduced to below 500 Pa absolute pressure within 30 minutes. The reaction temperature is 260° C. and the reaction time is 30 minutes. Then the vacuum is continued to be drawn to carry out the polycondensation reaction in the high vacuum stage. In this stage, the reaction pressure is further reduced to below 80 Pa absolute pressure. The reaction temperature is 275° C. and the reaction time is 50 minutes to obtain the cationic polyester.

[0035] The molar ratio of terephthalic acid, ethylene glycol, and 1,2-octanediol is 1:1.2:0.10.

[0036] The amount of the catalyst added is 0.015% of the weight of terephthalic acid, the amount of the matting agent added is 0.20% of the weight of terephthalic acid, and the amount of the stabilizer added is 0.01% of the weight of terephthalic acid. The catalyst is antimony trioxide, the matting agent is titanium dioxide, and the stabilizer is triphenyl phosphate.

[0037] The cationic polyester fiber has a single filament fineness of 0.6 dtex, a breaking strength of 3.36 cN / dtex, an elongation at break of 22.0%, a linear density deviation rate of 1.28%, a breaking strength CV value of 6.00%, a breaking elongation CV value of 7.8%, a boiling water shrinkage rate of 4.5%, a curl stability of 76%, and a curl shrinkage rate of 7%. Example

[0038] A cationic polyester fiber, the cationic polyester comprises a terephthalic acid segment, an ethylene glycol segment, a 1,2-octanediol segment and a 5-sodium sulfoisophthalic acid segment, the molar content of the 1,2-octanediol in the cationic polyester is 9%, and the molar content of the 5-sodium sulfoisophthalic acid in the cationic polyester is 1.8%.

[0039] A method for preparing a cationic polyester fiber comprises the following steps: preparing the cationic polyester; The cationic polyester is melted to obtain a cationic polyester melt, the cationic polyester melt is pelletized to obtain a cationic polyester slice, and the cationic polyester slice is metered, spinneret extruded, cooled, oiled and wound to obtain a POY yarn; The POY yarn is passed through a guide yarn, a first roller, a first hot box for heating, a cooling plate, a second roller, a twister, a third roller, a second hot box, oiling, and winding to obtain a DTY yarn, namely the cationic polyester fiber.

[0040] When the shear rate of the cationic polyester melt is 2000 / s, the viscosity activation energy thereof is 72.5 kJ / mol, and the intrinsic viscosity of the cationic polyester melt is 0.63 dL / g.

[0041] The spinning temperature for preparing the POY yarn is 282° C., the cooling temperature is 21° C., and the winding speed is 3400 m / min.

[0042] The spinning speed for preparing the DTY yarn is 600 m / min, the shaping overfeed rate is 4.5%, the winding overfeed rate is 3%, the first hot box temperature is 200° C., the second hot box temperature is 170° C., and the stretching ratio is 1.6.

[0043] The specific steps for preparing the cationic polyester are as follows: Terephthalic acid, ethylene glycol and 1,2-octanediol were prepared into slurry, and catalyst, matting agent and stabilizer were added and mixed evenly, and then esterification reaction was carried out under pressure in nitrogen atmosphere, and the pressure was 0.3MPa, and the temperature of esterification reaction was 255℃. When the amount of water distilled in the esterification reaction reached more than 95% of the theoretical value, the esterification reaction was terminated. After the esterification reaction, sodium ethylene glycol 5-sulfonate was added and stirred for 27 minutes; The polycondensation reaction in the low vacuum stage is started under negative pressure conditions. The pressure in this stage is reduced to below 500 Pa absolute pressure within 40 minutes. The reaction temperature is 265° C. and the reaction time is 40 minutes. Then the vacuum is continued to be drawn to carry out the polycondensation reaction in the high vacuum stage. In this stage, the reaction pressure is further reduced to below 80 Pa absolute pressure. The reaction temperature is 277° C. and the reaction time is 70 minutes to obtain the cationic polyester.

[0044] The molar ratio of terephthalic acid, ethylene glycol, and 1,2-octanediol is 1:1.3:0.085.

[0045] The added amount of the catalyst is 0.017% of the weight of terephthalic acid, the added amount of the matting agent is 0.22% of the weight of terephthalic acid, and the added amount of the stabilizer is 0.02% of the weight of terephthalic acid. The catalyst is antimony acetate, the matting agent is titanium dioxide, and the stabilizer is trimethyl phosphite.

[0046] The cationic polyester fiber has a single filament fineness of 1.0 dtex, a breaking strength of 3.55 cN / dtex, an elongation at break of 26.0%, a linear density deviation rate of 1.2%, a breaking strength CV value of 5%, a breaking elongation CV value of 7.0%, a boiling water shrinkage rate of 4.1%, a curl stability of 77%, and a curl shrinkage rate of 8.2%. Example

[0047] A cationic polyester fiber, the cationic polyester comprising a terephthalic acid segment, an ethylene glycol segment, a 1,2-octanediol segment and a 5-sodium sulfoisophthalic acid segment, the molar content of the 1,2-octanediol in the cationic polyester is 10.0%, and the molar content of the 5-sodium sulfoisophthalic acid in the cationic polyester is 2.0%.

[0048] A method for preparing a cationic polyester fiber comprises the following steps: preparing the cationic polyester; The cationic polyester is melted to obtain a cationic polyester melt, the cationic polyester melt is pelletized to obtain a cationic polyester slice, and the cationic polyester slice is metered, spinneret extruded, cooled, oiled and wound to obtain a POY yarn; The POY yarn is passed through a guide yarn, a first roller, a first hot box for heating, a cooling plate, a second roller, a twister, a third roller, a second hot box, oiling, and winding to obtain a DTY yarn, namely the cationic polyester fiber.

[0049] When the shear rate of the cationic polyester melt is 3000 / s, the viscosity activation energy thereof is 62.3 kJ / mol, and the intrinsic viscosity of the cationic polyester melt is 0.65 dL / g.

[0050] The spinning temperature for preparing the POY yarn is 285° C., the cooling temperature is 22° C., and the winding speed is 3600 m / min.

[0051] The spinning speed for preparing the DTY yarn is 700 m / min, the shaping overfeed rate is 5.5%, the winding overfeed rate is 5.0%, the first hot box temperature is 220° C., the second hot box temperature is 180° C., and the stretching ratio is 1.7.

[0052] The specific steps for preparing the cationic polyester are as follows: Terephthalic acid, ethylene glycol and 1,2-octanediol are prepared into slurry, and a catalyst, a matting agent and a stabilizer are added and mixed evenly, and then the mixture is pressurized in a nitrogen atmosphere for esterification reaction. The pressurization pressure is 0.3 MPa, and the temperature of the esterification reaction is 260°C. When the amount of water distilled in the esterification reaction reaches more than 95% of the theoretical value, the esterification reaction ends. After the esterification reaction, sodium 5-sulfonate of ethylene glycol isophthalate is added and stirred for 30 minutes. The polycondensation reaction in the low vacuum stage is started under negative pressure conditions. The pressure in this stage is reduced to below 500Pa absolute pressure within 50 minutes. The reaction temperature is 270°C and the reaction time is 50 minutes. Then the vacuum is continued to be drawn to carry out the polycondensation reaction in the high vacuum stage. In this stage, the reaction pressure is further reduced to below 80Pa absolute pressure. The reaction temperature is 280°C and the reaction time is 50-90 minutes to obtain the cationic polyester.

[0053] The molar ratio of terephthalic acid, ethylene glycol, and 1,2-octanediol is 1:1.4:0.09.

[0054] The amount of the catalyst added is 0.020% of the weight of terephthalic acid, the amount of the matting agent added is 0.20-0.25% of the weight of terephthalic acid, the amount of the stabilizer added is 0.03% of the weight of terephthalic acid, the catalyst is antimony ethylene glycol, the matting agent is titanium dioxide, and the stabilizer is trimethyl phosphate.

[0055] The cationic polyester fiber has a single filament fineness of 1.2 dtex, a breaking strength of 3.62 cN / dtex, an elongation at break of 28%, a linear density deviation rate of 1.12%, a breaking strength CV value of 4.90%, a breaking elongation CV value of 6.8%, a boiling water shrinkage of 4.5%, a curl stability of 80%, and a curl shrinkage of 9.0%.

[0056] It can be seen from Examples 1, 2 and 3 that when the cationic polyester melt is sheared, its viscosity flow activation energy is reasonable, and while the viscosity of the cationic polyester melt decreases, the thermal properties and crystallization properties of the cationic polyester are slightly affected, thereby improving the spinnability of the cationic polyester melt, and the prepared cationic polyester fiber has good mechanical properties.

[0057] Any numerical value cited herein includes all values ​​of lower and upper values ​​that increase by one unit from the lower limit to the upper limit, and there is at least a two-unit interval between any lower value and any higher value. For example, if the value of the quantity of a component or a process variable (such as temperature, pressure, time, etc.) is set forth to be from 1 to 90, preferably from 20 to 80, and more preferably from 30 to 70, the purpose is to illustrate that values ​​such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also explicitly listed in the specification. For values ​​less than 1, one unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1. These are merely examples that are intended to be clearly expressed, and it can be considered that all possible combinations of numerical values ​​listed between the lowest value and the highest value are clearly set forth in the specification in a similar manner.

[0058] Unless otherwise indicated, all ranges include the endpoints and all numbers between the endpoints. "About" or "approximately" used with a range applies to both endpoints of the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30", including at least the specified endpoints.

[0059] All articles and references disclosed, including patent applications and publications, are incorporated herein by reference for all purposes. The term "consisting essentially of..." to describe a combination should include the identified elements, ingredients, parts or steps and other elements, ingredients, parts or steps that do not substantially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe a combination of elements, ingredients, parts or steps herein also contemplates embodiments that consist essentially of these elements, ingredients, parts or steps. By using the term "may", it is intended to indicate that any attribute described that "may" include is optional.

[0060] Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure "one" or "an" used to describe an element, ingredient, part or step is not intended to exclude other elements, ingredients, parts or steps.

[0061] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but should be determined with reference to the appended claims and the full scope of equivalents possessed by such claims. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of the subject matter, nor should it be considered that the inventors did not consider the subject matter to be part of the disclosed inventive subject matter.

Claims

1. A cationic polyester fiber, characterized in that: The cationic polyester comprises a terephthalic acid segment, an ethylene glycol segment, a 1,2-octanediol segment and a 5-sodium sulfoisophthalic acid segment, and the molar content of the 1,2-octanediol in the cationic polyester is 8.5-10.0%.

2. The cationic polyester fiber according to claim 1, characterized in that The molar content of the sodium 5-sulfoisophthalate in the cationic polyester is 1.5-2.0%.

3. The method for preparing the cationic polyester fiber according to any one of claims 1 to 2, characterized in that: The following steps are involved: preparing the cationic polyester; The cationic polyester is melted to obtain a cationic polyester melt, the cationic polyester melt is pelletized to obtain a cationic polyester slice, and the cationic polyester slice is metered, spinneret extruded, cooled, oiled and wound to obtain a POY yarn; The POY yarn is guided, heated and stretched, twisted, heat-set and wound to obtain DTY yarn, namely the cationic polyester fiber.

4. The method for preparing cationic polyester fiber according to claim 3, characterized in that: When the shear rate of the cationic polyester melt is between 1000 / s and 3000 / s, the viscosity activation energy thereof is between 75.4 and 62.3 kJ / mol, and the intrinsic viscosity of the cationic polyester melt is between 0.62 and 0.65 dL / g.

5. The method for preparing cationic polyester fiber according to claim 3, characterized in that: The spinning temperature for preparing the POY yarn is 280-285° C., the cooling temperature is 20-22° C., and the winding speed is 3200-3600 m / min.

6. The method for preparing cationic polyester fiber according to claim 3, characterized in that: The spinning speed for preparing the DTY yarn is 500-700 m / min, the shaping overfeed rate is 3.5-5.5%, the winding overfeed rate is 2.5-5.0%, the first hot box temperature is 180-220° C., the second hot box temperature is 150-180° C., and the stretching ratio is 1.5-1.

7.

7. The method for preparing cationic polyester fiber according to claim 3, characterized in that: The specific steps for preparing the cationic polyester are as follows: Terephthalic acid, ethylene glycol and 1,2-octanediol are prepared into slurry, and a catalyst, a matting agent and a stabilizer are added and mixed evenly, and then the mixture is pressurized in a nitrogen atmosphere for esterification reaction, and the pressurization pressure is 0.3 MPa, and the temperature of the esterification reaction is 250-260°C. When the amount of water distilled in the esterification reaction reaches more than 95% of the theoretical value, the esterification reaction ends. After the esterification reaction, sodium ethylene glycol 5-sulfonate is added and stirred for 25-30 minutes; The polycondensation reaction in the low vacuum stage is started under negative pressure conditions. The pressure in this stage is steadily pumped from normal pressure to an absolute pressure below 500Pa within 30-50min, the reaction temperature is 260-270°C, and the reaction time is 30-50min. Then, the vacuum is continued to be pumped to carry out the polycondensation reaction in the high vacuum stage. In this stage, the reaction pressure is further reduced to an absolute pressure below 80Pa, the reaction temperature is 275-280°C, and the reaction time is 50-90min to obtain the cationic polyester.

8. The method for preparing cationic polyester fiber according to claim 7, characterized in that: The molar ratio of terephthalic acid, ethylene glycol and 1,2-octanediol is 1:(1.2-1.4):(0.085-0.10).

9. The method for preparing cationic polyester fiber according to claim 7, characterized in that: The catalyst is added in an amount of 0.015-0.020% by weight of terephthalic acid, the matting agent is added in an amount of 0.20-0.25% by weight of terephthalic acid, and the stabilizer is added in an amount of 0.01-0.03% by weight of terephthalic acid; The catalyst is one of antimony trioxide, ethylene glycol antimony or antimony acetate, the matting agent is titanium dioxide, and the stabilizer is one of triphenyl phosphate, trimethyl phosphate or trimethyl phosphite.

10. The method for preparing cationic polyester fiber according to claim 3, characterized in that: The cationic polyester fiber has a monofilament fineness of 0.6-1.2 dtex, a breaking strength of ≥3.3 cN / dtex, an elongation at break of 25.0±3.0%, a linear density deviation rate of ≤1.30%, a breaking strength CV value of ≤6.00%, a breaking elongation CV value of ≤8.0%, a boiling water shrinkage of 4.0±0.5%, a curl stability of ≥75%, and a curl shrinkage of 8.0±1.0%.