Modified polyester fiber yarn and preparation process thereof

Abstract

The invention relates to a modified polyester fiber yarn and a preparation process thereof. The preparation process comprises the following steps: 1, preparing alkali deweighting fibers; 2, preparing aminated polyester fibers; thirdly, activated polyester fibers are prepared; 4, preparing modified polyester fibers; 5, the modified polyester fibers are processed through a stretching false twisting technology, and the modified polyester fiber yarn is prepared. The modified polyester fiber subjected to special treatment is selected on the raw material, the yarn obtained by carrying out stretching and false twisting treatment on the fiber material can form a compact structure which is not prone to transverse damage, the outer-layer fiber generates inclined spiral line twisting, the fiber is twisted and deformed, slivers are tightly cohered, and therefore the yarn has a good anti-static effect. On the basis of keeping the structural form and mechanical and physical properties of the traditional polyester fiber yarn, the hygroscopicity, antistatic property and high-temperature stability of the yarn are improved, in addition, the quality feeling is enhanced, and the prepared fabric can meet the good comfort requirement of external wearing.

Description

Technical Field

[0001] The present invention relates to the field of fabric fibers, and particularly to a modified polyester fiber yarn and its preparation process. Background Art

[0002] With the innovative development of fiber technology, textile chemistry technology, and textile machinery technology, and the improvement of the material living standards of residents, for various textiles closely related to daily work and life, the basic wearing performance of clothing can no longer fully meet the needs of consumers. People have begun to pay more attention to the quality of life, pursue safety, health, green environmental protection, and functional textiles with special effects, which are increasingly favored by consumers. The rapid development of tourism and outdoor sports has led to more and more requirements for the wearing comfort and functionality of clothing. Synthetic chemical fiber fabrics are straight and not easily deformed in appearance and have relatively fast moisture emission characteristics. Therefore, differential-shaped fiber materials are more suitable for the increasingly diversified needs of consumers.

[0003] The false twist spinning process of polyester fiber is a spinning technology that endows fibers with special properties through specific processing methods and is widely used in the production of yarns with high elasticity and good softness. False twist spinning applies a torsional force when the fibers are in a bundle to form twist, but there is no actual twist on the final yarn. This process utilizes the thermoplasticity of the fibers to fix the crimp and elastic effects during the heating and cooling processes. The fibers produced by the false twist process have good softness, elasticity, and extensibility and are suitable for manufacturing socks, coats, seamless clothing, functional sportswear, etc. Although the false twist yarn of polyester fiber has various advantages, the current false twist yarn of polyester fiber on the market has obvious defects in terms of moisture absorption, antistatic, and high-temperature stability, which limit its application in some high-end or textiles with higher comfort requirements. Summary of the Invention

[0004] Aiming at the problems existing in the prior art, the purpose of the present invention is to provide a modified polyester fiber yarn and its preparation process.

[0005] The purpose of the present invention is achieved by the following technical solutions:

[0006] In the first aspect, the present invention provides a preparation process of a modified polyester fiber yarn, including the following steps:

[0007] The first step: Soak the polyester fiber in a sodium hydroxide solution for alkali weight reduction treatment to obtain alkali weight-reduced fiber;

[0008] The second step: Add the alkali weight-reduced fiber and an amino silane coupling agent to an ethanol solution and perform a temperature-raising treatment to obtain amino-modified polyester fiber;

[0009] Step 3: Weigh 2-furylacrolein and anhydrous ethanol, mix them, then add amino-functionalized polyester fiber. After dispersing evenly, react under the action of a catalyst to obtain activated polyester fiber;

[0010] Step 4: Weigh N-vinylcaprolactam and an azo initiator, add them to anhydrous ethanol. After fully dissolving, add the activated polyester fiber, raise the temperature and stir to react to obtain modified polyester fiber;

[0011] Step 5: Process the modified polyester fiber through a draw texturing process to prepare modified polyester fiber yarn.

[0012] Preferably, in the first step, the mass fraction of the sodium hydroxide solution is 5% - 25%, and the mass ratio of the polyester fiber to the sodium hydroxide solution is 1:10 - 20.

[0013] Preferably, in the first step, the treatment temperature is 20 - 40°C, and the treatment time is 1 - 3 h.

[0014] Preferably, in the second step, the mass fraction of the ethanol solution is 20% - 80%, and the amino-silane coupling agent is KH-550 or KH-602.

[0015] Preferably, in the second step, the mass ratio of the alkali-weight-reduced fiber, the amino-silane coupling agent, and the ethanol solution is 1:0.1 - 0.5:15 - 25.

[0016] Preferably, in the second step, the treatment temperature is 50 - 70°C, and the treatment time is 2 - 6 h.

[0017] Preferably, in the third step, the mass ratio of the amino-functionalized polyester fiber, 2-furylacrolein, and anhydrous ethanol is 1:0.12 - 0.24:15 - 25.

[0018] Preferably, in the third step, the reaction temperature is 70 - 80°C, and the reaction time is 2 - 8 h.

[0019] Preferably, in the third step, the catalyst is triethylamine, and the addition amount is 3% - 10% of the mass of 2-furylacrolein.

[0020] Preferably, in the fourth step, the mass ratio of the activated polyester fiber, N-vinylcaprolactam, and anhydrous ethanol is 1:0.14 - 0.28:20 - 30.

[0021] Preferably, in the fourth step, the initiator is an azo initiator, specifically azobisisobutyronitrile or azobis(2,4-dimethylvaleronitrile).

[0022] Preferably, in the fourth step, the addition amount of the initiator is 2% - 7% of the mass of N-vinylcaprolactam.

[0023] Preferably, in the fourth step, the reaction temperature is 55 - 75 °C and the reaction time is 4 - 10 h.

[0024] Preferably, in the fifth step, the process of the draw texturing process includes: elongating and stretching the fiber through the guidance of a drawing machine. During this process, a false twister is used to twist the fiber together by rotation for twisting treatment, followed by setting treatment, and then untwisting treatment to make the final twist 0, and then winding treatment to form the required yarn.

[0025] Preferably, in the fifth step, the draft ratio is 1.12 - 1.28, the twist of twisting is 1200 - 3500 T / m, and the setting temperature is 120 - 170 °C.

[0026] In a second aspect, the present invention provides a modified polyester fiber yarn prepared by the above preparation method.

[0027] Preferably, the specifications of the modified polyester fiber yarn are one of 24D / 28F, 50D / 72F, 50D / 144F, 75D / 72F, 75D / 144F, 75D / 288F, 150D / 288F, 150D / 288F, 150D / 576F.

[0028] The beneficial effects of the present invention are as follows:

[0029] 1. The present invention selects a specially treated modified polyester fiber as the raw material. The yarn obtained by subjecting this fiber material to draw texturing treatment can form a tight structure that is not easily damaged laterally. The outer layer fibers generate inclined helical twist turns, the fibers are twisted and deformed, and the yarn strips are tightly held together. On the basis of maintaining the structural form and mechanical and physical properties of traditional polyester fiber yarns, the hygroscopicity, antistatic property, and high-temperature stability of the yarn are improved. In addition, the quality sense is enhanced, enabling the prepared fabric to meet the good comfort requirements for outer wear.

[0030] 2. The modification treatment of the polyester fiber in the present invention includes successively carried out processes of alkali weight reduction, amination, enal activation, and surface polymerization. Among them, the role of alkali weight reduction is to increase the surface activity of the fiber and increase the specific surface area of the fiber. Amination is to carry out amino grafting using the hydrolysis of a silane coupling agent. Enal activation is to carry out an amine-aldehyde condensation reaction between acrolein containing a furyl group and the amino group on the fiber surface. Surface polymerization is to carry out initiation polymerization between N-vinylcaprolactam containing a double bond and the double bond on the fiber surface, and finally a modified polyester fiber is prepared.

[0031] 3. The furan groups introduced during the enal activation process of the modified polyester fiber and the generated Schiff base groups can exhibit good hydrophilicity, thereby improving the moisture absorption and quick-drying properties of the fiber. In addition, the introduced double bond groups can participate in the subsequent polymerization reaction of N-vinylcaprolactam. Moreover, the furan groups and Schiff base groups endow the fiber with certain antibacterial properties.

[0032] 4. Currently, in order to endow polyester fibers with certain moisture absorption properties, they are usually subjected to alkali weight reduction treatment in the market. Although alkali weight reduction can increase the surface activity of the fiber, it will somewhat reduce the strength of the fiber. To solve this problem, in the present invention, by introducing N-vinylcaprolactam containing caprolactam and performing polymerization coating treatment on the surface of the fiber, the strength lost due to weight reduction can be better compensated. Specific Embodiments

[0033] The technical solutions of the present invention are described below through specific specific examples. It should be understood that one or more method steps mentioned in the present invention do not exclude the existence of other method steps before and after the combined steps or the insertion of other method steps between these clearly mentioned steps; it should also be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. Moreover, unless otherwise specified, the numbers of each method step are only convenient tools for identifying each method step, rather than limiting the arrangement order of each method step or the scope of implementation of the present invention. The change or adjustment of their relative relationship, without substantial change in technical content, should also be regarded as the scope of implementation of the present invention.

[0034] To better understand the above technical solutions, the exemplary embodiments of the present invention are described in more detail below. Although the exemplary embodiments of the present invention are shown, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to convey the scope of the present invention completely to those skilled in the art.

[0035] The present invention is further described below in conjunction with the following embodiments.

[0036] Example 1

[0037] A preparation process of a modified polyester fiber yarn includes the following steps:

[0038] The first step, alkali weight reduction treatment:

[0039] The polyester fiber (with a density of 1.39 g / cm 3(0) is mixed with a sodium hydroxide solution with a mass fraction of 15%. The mass ratio of the polyester fiber to the sodium hydroxide solution is 1:15. It is soaked and stirred at 30 °C for 2 h. After the treatment, the fiber is filtered, washed with water until the washing liquid is neutral, and then dried to obtain the fiber with reduced alkali content;

[0040] Step 2, amination treatment:

[0041] The fiber with reduced alkali content is mixed with an ethanol solution with a mass fraction of 60%, and an amino silane coupling agent KH-550 is added. The mass ratio of the fiber with reduced alkali content, the amino silane coupling agent, and the ethanol solution is 1:0.3:20. It is heated to 60 °C and kept warm for 4 h. After the treatment, the fiber is filtered, washed with water 3 times, and then dried to obtain the aminated polyester fiber;

[0042] Step 3, enal activation treatment:

[0043] Weigh 2-furylacrolein and mix it with absolute ethanol. Stir well until it is dissolved evenly. Add the aminated polyester fiber. The mass ratio of the aminated polyester fiber, 2-furylacrolein, and absolute ethanol is 1:0.18:20. After dispersing evenly, add triethylamine which is 6% of the mass of 2-furylacrolein as a catalyst. Under the protection of nitrogen, it is heated to 75 °C and refluxed and stirred for 5 h. After the reaction, the solvent is removed under reduced pressure, washed with water 3 times, and then dried to obtain the activated polyester fiber;

[0044] Step 4, surface polymerization treatment:

[0045] Weigh N-vinylcaprolactam and add it to absolute ethanol. After fully dissolving, add the activated polyester fiber. The mass ratio of the activated polyester fiber, N-vinylcaprolactam, and absolute ethanol is 1:0.21:25. Stir and disperse evenly. Under the protection of nitrogen, add an initiator azobisisobutyronitrile. The addition amount is 5% of the mass of N-vinylcaprolactam. It is heated to 65 °C and kept warm for 8 h. After the stirring treatment, the solvent is removed under reduced pressure, washed with alcohol 3 times, and then dried to obtain the modified polyester fiber;

[0046] Step 5, preparing yarn:

[0047] The modified polyester fiber is guided by a stretching machine for elongation and stretching. The draw ratio is 1.24. During this process, a false twister is used to wind the fibers together by rotation for twisting treatment. The twist of the twist is 2300 T / m. Then it is subjected to a setting treatment at 140 °C, and then untwisted to make the final twist 0. Then it is subjected to a winding treatment to prepare a modified polyester fiber yarn with a specification of 50D / 144F.

[0048] Example 2

[0049] A preparation process of a modified polyester fiber yarn, comprising the following steps:

[0050] First step, alkali weight reduction treatment:

[0051] Mix polyester fiber and a sodium hydroxide solution with a mass fraction of 5%. The mass ratio of polyester fiber to sodium hydroxide solution is 1:10. Soak and stir at 20 °C for 1 h. After the treatment, filter to collect the fiber, rinse with water until the washing liquid is neutral, and then dry to obtain alkali weight-reduced fiber;

[0052] Second step, amination treatment:

[0053] Mix the alkali weight-reduced fiber and an ethanol solution with a mass fraction of 20%, and add the amino silane coupling agent KH-550. The mass ratio of alkali weight-reduced fiber, amino silane coupling agent to ethanol solution is 1:0.1:15. Heat up to 50 °C and keep warm for 2 h. After the treatment, filter to collect the fiber, rinse with water twice, and then dry to obtain aminated polyester fiber;

[0054] Third step, enal activation treatment:

[0055] Weigh 2-furylacrolein and mix it with absolute ethanol. Stir well until dissolved uniformly, then add the aminated polyester fiber. The mass ratio of aminated polyester fiber, 2-furylacrolein to absolute ethanol is 1:0.12:15. After dispersing uniformly, add triethylamine which is 3% of the mass of 2-furylacrolein as a catalyst. Under the protection of nitrogen, heat up to 70 °C and reflux and stir for 2 h. After the reaction, remove the solvent under reduced pressure, wash twice with water, and then dry to obtain activated polyester fiber;

[0056] Fourth step, surface polymerization treatment:

[0057] Weigh N-vinylcaprolactam and add it to absolute ethanol. After fully dissolving, add the activated polyester fiber. The mass ratio of activated polyester fiber, N-vinylcaprolactam to absolute ethanol is 1:0.14:20. Stir and disperse uniformly. Under the protection of nitrogen, add the initiator azobisisobutyronitrile, and the addition amount is 2% of the mass of N-vinylcaprolactam. Heat up to 55 °C and keep warm for 4 h. After the stirring treatment, remove the solvent under reduced pressure, wash twice with alcohol, and then dry to obtain modified polyester fiber;

[0058] Fifth step, preparing yarn:

[0059] The modified polyester fiber is elongated and stretched through the guidance of a stretching machine, and the draft ratio is 1.12. During this process, a false twister is used to twist the fibers together by rotation for twisting treatment. The twist of the twisting is 1200 T / m. After that, it is subjected to a setting treatment at 120 °C, and then a untwisting treatment is carried out to make the final twist 0. Then, through winding treatment, a modified polyester fiber yarn with a specification of 24 D / 28 F is prepared.

[0060] Example 3

[0061] A preparation process of a modified polyester fiber yarn, comprising the following steps:

[0062] The first step, alkali weight reduction treatment:

[0063] Mix the polyester fiber and a sodium hydroxide solution with a mass fraction of 25%. The mass ratio of the polyester fiber to the sodium hydroxide solution is 1:20. Soak and stir at 40 °C for 3 h. After the treatment is completed, filter to collect the fiber, rinse with water until the washing liquid is neutral, and then dry to obtain the alkali weight-reduced fiber;

[0064] The second step, amination treatment:

[0065] Mix the alkali weight-reduced fiber and an ethanol solution with a mass fraction of 80%, add the amino silane coupling agent KH-602. The mass ratio of the alkali weight-reduced fiber, the amino silane coupling agent to the ethanol solution is 1:0.5:25. Heat up to 70 °C and keep warm for 6 h. After the treatment is completed, filter to collect the fiber, rinse with water 5 times, and then dry to obtain the aminated polyester fiber;

[0066] The third step, enal activation treatment:

[0067] Weigh 2-furylacrolein and anhydrous ethanol and mix them, stir well until dissolved uniformly, add the aminated polyester fiber. The mass ratio of the aminated polyester fiber, 2-furylacrolein to anhydrous ethanol is 1:0.24:25. After dispersing uniformly, add triethylamine which is 10% of the mass of 2-furylacrolein as a catalyst. Under the protection of nitrogen, heat up to 80 °C and carry out reflux stirring for 8 h. After the reaction is completed, remove the solvent under reduced pressure, wash with water 5 times, and then dry to obtain the activated polyester fiber;

[0068] The fourth step, surface polymerization treatment:

[0069] Weigh N-vinylcaprolactam and add it to absolute ethanol. After it is fully dissolved, add activated polyester fiber. The mass ratio of activated polyester fiber, N-vinylcaprolactam and absolute ethanol is 1:0.28:30. Stir and disperse evenly. Under the protection of nitrogen, add initiator azodiisobutyronitrile, and the addition amount is 7% of the mass of N-vinylcaprolactam. Heat up to 75 °C and keep warm for 10 h. After the stirring treatment is over, remove the solvent under reduced pressure. After washing with alcohol 5 times, dry to obtain modified polyester fiber;

[0070] Step 5, Prepare yarn:

[0071] Pass the modified polyester fiber through the guide of a stretching machine for elongation and stretching. The draft ratio is 1.28. During this process, use a false twister to twist the fibers together by rotation for twisting treatment. The twist of twisting is 3500 T / m. Then, carry out setting treatment at 170 °C, and then carry out untwisting treatment to make the final twist 0. Then, through winding treatment, prepare modified polyester fiber yarn with a specification of 75D / 144F.

[0072] Comparative Example 1

[0073] A preparation process of modified polyester fiber yarn, which is different from Example 1 in that aminized polyester fiber is used to replace the modified polyester fiber in Example 1, that is:

[0074] Step 1, Carry out alkali weight reduction treatment to obtain alkali weight reduction fiber, which is the same as that in Example 1;

[0075] Step 2, Carry out aminization treatment to obtain aminized polyester fiber, which is the same as that in Example 1;

[0076] Step 3, Prepare yarn: Pass the aminized polyester fiber through the guide of a stretching machine for elongation and stretching. The draft ratio is 1.24. During this process, use a false twister to twist the fibers together by rotation for twisting treatment. The twist of twisting is 2300 T / m. Then, carry out setting treatment at 140 °C, and then carry out untwisting treatment to make the final twist 0. Then, through winding treatment, prepare modified polyester fiber yarn with a specification of 50D / 144F.

[0077] Comparative Example 2

[0078] A preparation process of modified polyester fiber yarn, which is different from Example 1 in that activated polyester fiber is used to replace the modified polyester fiber in Example 1, that is:

[0079] Step 1, Carry out alkali weight reduction treatment to obtain alkali weight reduction fiber, which is the same as that in Example 1;

[0080] Step 2, Carry out aminization treatment to obtain aminized polyester fiber, which is the same as that in Example 1;

[0081] Step 3: Activate the enal to obtain activated polyester fiber, which is the same as in Example 1;

[0082] Step 4: Prepare the yarn: Stretch and draw the activated polyester fiber through the guide of a drawing machine. The draft ratio is 1.24. During this process, use a false twister to twist the fibers together by rotation. The twist of the twisting is 2300 T / m. Then, perform a setting treatment at 140°C, and then perform a untwisting treatment to make the final twist 0. Then, perform a winding treatment to prepare a modified polyester fiber yarn with a specification of 50D / 144F.

[0083] Comparative Example 3

[0084] A preparation process of a modified polyester fiber yarn, which is different from Example 1 in that the preparation method of the modified polyester fiber is different, and the yarn preparation is the same as in Example 1. The preparation method of the modified polyester fiber includes:

[0085] Step 1: Perform an alkali weight reduction treatment to obtain alkali weight-reduced fiber, which is the same as in Example 1;

[0086] Step 2: Weigh 2-furanacrolein and N-vinylcaprolactam and add them to absolute ethanol. After fully dissolving, add the alkali weight-reduced fiber. The mass ratio of the alkali weight-reduced fiber, 2-furanacrolein, N-vinylcaprolactam, and absolute ethanol is 1:0.18:0.21:25. Stir and disperse evenly. Under the protection of nitrogen, add an initiator, azobisisobutyronitrile, and the addition amount is 5% of the mass of N-vinylcaprolactam. Heat up to 65°C and keep warm for 8 h. After the stirring treatment is completed, remove the solvent under reduced pressure, wash with alcohol 3 times, and then dry to obtain the modified polyester fiber.

[0087] The properties of the yarns prepared in Example 1 and Comparative Examples 1-3 were correspondingly detected. The detection items included breaking strength, moisture absorption (moisture regain), antistatic property, and Vicat softening temperature. Specifically:

[0088] 1. Breaking strength: Under standard atmospheric conditions (20±2°C, 65±5%RH), take three specimens of each type, and refer to the standard of GB / T3916-2013 to measure the breaking strength using an equal-speed tensile tester and take the average value.

[0089] 2. Moisture regain: Under standard atmospheric conditions (20±2°C, 65±5%RH), the detection standard refers to the oven drying method in GB / T9995-1997 "Determination Methods for Moisture Content and Moisture Regain of Textile Materials";

[0090] 3. Antistatic property: The detection standard refers to GB / T 12703.1-2008 "Evaluation of Electrostatic Properties of Textiles". The half-life decay time HDT is detected. The smaller the time, the better the antistatic property. Specifically, the evaluation is as follows: HDT ≤ 10 is excellent, 10 < HDT < 30 is good, 30 < HDT < 60 is fair, and 60 < HDT is poor.

[0091] 4. Vicat softening temperature: The detection standard refers to GB / T 1633-2000 "Determination of Vicat Softening Temperature (VST) of Thermoplastics", and the average value is taken after multiple detections.

[0092] The detection results are shown in Table 1:

[0093] Table 1 Performance Detection Results of Different Yarns

[0094] Example 1 Comparative Example 1 Comparative Example 2 Comparative Example 3 Breaking strength (cN) 638.5 427.1 506.9 549.2 Moisture regain 2.1% 2.4% 2.0% 1.8% Antistatic property Better Better Better Good Vicat softening temperature (°C) 269 212 235 247

[0095] It can be seen from the detection results in Table 1 that the yarn prepared in Example 1 of the present invention can maintain high hygroscopicity (moisture regain) and antistatic property, and also has excellent strength and high temperature resistance, solving the problems existing in the alkali-deweighted polyester fiber yarns on the market at present.

[0096] In the description of this specification, the descriptions with reference to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms should not be understood as necessarily referring to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine the different embodiments or examples described in this specification.

[0097] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

Claims

1. A process for preparing modified polyester fiber yarn, characterized in that: The following steps are involved: The first step is to immerse the polyester fiber in a sodium hydroxide solution to perform an alkali weight reduction treatment to obtain an alkali weight-reduced fiber; The second step is to add the alkali-reduced fiber and the aminosilane coupling agent into the ethanol solution and heat the solution to obtain the amino polyester fiber; Step 3: Weigh 2-furanpropenal and anhydrous ethanol, mix them, add the amino polyester fiber, disperse them evenly, and react under the action of a catalyst to obtain activated polyester fiber; Step 4: weigh N-vinyl caprolactam and azo initiator and add them to anhydrous ethanol. After fully dissolving, add activated polyester fiber, heat and stir to react, and obtain modified polyester fiber. The fifth step is to process the modified polyester fiber through a stretching false twisting process to prepare modified polyester fiber yarn.

2. The process for preparing a modified polyester fiber yarn according to claim 1, characterized in that: In the first step, the mass fraction of the sodium hydroxide solution is 5%-25%, and the mass ratio of the polyester fiber to the sodium hydroxide solution is 1:10-20; in the first step, the treatment temperature is 20-40° C., and the treatment time is 1-3 hours.

3. The process for preparing a modified polyester fiber yarn according to claim 1, characterized in that: In the second step, the mass fraction of the ethanol solution is 20%-80%, the aminosilane coupling agent is KH-550 or KH-602; the mass ratio of the alkali-reduced fiber, the aminosilane coupling agent and the ethanol solution is 1:0.1-0.5:15-25.

4. The process for preparing a modified polyester fiber yarn according to claim 1, characterized in that: In the second step, the treatment temperature is 50-70° C., and the treatment time is 2-6 hours.

5. The process for preparing a modified polyester fiber yarn according to claim 1, characterized in that: In the third step, the mass ratio of the aminated polyester fiber, 2-furanacrolein and anhydrous ethanol is 1:0.12-0.24:15-25; the catalyst is triethylamine, and the added amount is 3%-10% of the mass of 2-furanacrolein.

6. The process for preparing modified polyester fiber yarn according to claim 1, characterized in that: In the third step, the reaction temperature is 70-80° C. and the reaction time is 2-8 h.

7. The process for preparing modified polyester fiber yarn according to claim 1, characterized in that: In the fourth step, the mass ratio of activated polyester fiber, N-vinyl caprolactam and anhydrous ethanol is 1:0.14-0.28:20-30; the reaction temperature is 55-75° C., and the reaction time is 4-10 hours.

8. The process for preparing modified polyester fiber yarn according to claim 1, characterized in that: In the fourth step, the initiator is an azo initiator, specifically azobisisobutyronitrile or azobisisoheptanenitrile; the amount of the initiator added is 2%-7% of the mass of N-vinylcaprolactam.

9. The process for preparing modified polyester fiber yarn according to claim 1, characterized in that: In the fifth step, the drafting multiple is 1.12-1.28, the twisting degree is 1200-3500 T / m, and the setting temperature is 120-170°C.

10. A modified polyester fiber yarn, characterized in that: The modified polyester fiber yarn is prepared by the preparation process described in claim 1.