Super-soft cotton-like polyester fiber and production process thereof

Abstract

The invention discloses a super-soft cotton-like polyester fiber and a production process thereof, and belongs to the technical field of polyester fibers. The super-soft cotton-like polyester fiber comprises a core layer and a skin layer; wherein the core layer is prepared from the following components in parts by weight: 80 to 100 parts of polyethylene glycol terephthalate slices, 10 to 20 parts of epoxy polysiloxane and 0.5 to 2 parts of antioxidant; the skin layer is prepared from the following components in parts by weight: 50 to 70 parts of poly (trimethylene terephthalate) slices and 20 to 30 parts of polyether amine flexible polymer; wherein the polyether amine flexible polymer is prepared from a dianhydride polymer and a polyether amine polymer. According to the production process, sheath-core composite spinning is adopted, the core layer is subjected to melt extrusion at 260-270 DEG C, and the sheath layer is subjected to melt extrusion at 220-230 DEG C. The super-soft cotton-like polyester fiber has super-soft cotton-like touch feeling and good mechanical property through skin-core structure synergy.

Description

Technical Field

[0001] This invention belongs to the field of polyester fiber technology, and specifically relates to an ultra-soft cotton-like polyester fiber and its production process. Background Technology

[0002] Polyethylene terephthalate (PET) fiber has become the world's largest-produced synthetic fiber due to its high strength, high modulus, good heat resistance, and low cost. However, the high rigidity and crystallinity of PET molecular chains result in a stiff feel, poor resilience, and insufficient drape. When worn, it lacks the softness, fluffiness, and skin-friendly feel of cotton fibers, failing to meet consumers' demand for ultra-cotton-like comfort.

[0003] To impart a soft, cotton-like feel to PET polyester fibers, existing technologies typically employ physical or chemical modification methods. Physical methods mainly include using shaped spinnerets to prepare fibers with irregular cross-sections, subjecting fibers to alkali reduction treatment to etch their surface and increase roughness, or blending with natural fibers such as cotton. While these methods can improve the feel to some extent, the effects are limited and unsustainable. Alkali reduction treatment also leads to a significant loss of fiber strength and causes environmental pollution. Chemical methods primarily involve copolymerizing PET, for example, by introducing a third monomer, such as isophthalic acid and polyethylene glycol, to disrupt the regularity of the molecular chains, reduce its crystallinity and glass transition temperature, thereby increasing the fiber's softness. However, copolymerization modification often comes at the cost of sacrificing PET's inherent excellent mechanical properties and dimensional stability, and the process is complex and costly.

[0004] Core-sheath composite spinning technology can produce fibers with properties combining multiple components by using two or more polymers with different properties as the sheath and core layers respectively. However, how to select functional components that are both highly compatible with PET and extremely soft for the sheath layer is a technical problem that urgently needs to be solved in the construction of high-performance core-sheath structure cotton-like fibers. Summary of the Invention

[0005] The purpose of this invention is to provide an ultra-soft cotton-like polyester fiber to solve the problems of insufficient softness and lack of cotton-like properties in existing PET polyester fibers.

[0006] The present invention also aims to provide a method for preparing ultra-soft cotton-like polyester fiber, which is used to prepare ultra-soft cotton-like polyester fiber.

[0007] In a first aspect, the present invention provides an ultra-soft cotton-like polyester fiber, comprising a core layer and a sheath layer; The core layer comprises the following components by weight: 80-100 parts of polyethylene terephthalate chips, 10-20 parts of epoxy-based polysiloxane, and 0.5-2 parts of antioxidant; The cortex comprises the following components by weight: 50-70 parts of 1,3-propylene terephthalate chips and 20-30 parts of polyetheramine flexible polymer; The raw materials for the polyetheramine flexible polymer include dianhydride compounds and polyetheramine compounds in a molar ratio of 1:(1.2-4).

[0008] Preferably, the epoxy polysiloxane includes one or a combination of two of side-chain epoxy polysiloxanes and terminal-chain epoxy polysiloxanes.

[0009] Preferably, the dianhydride compound includes one or more of cyclohexanetetracarboxylic dianhydride, ethylenediaminetetraacetic dianhydride, naphthalenetetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, and pyromellitic dianhydride.

[0010] Preferably, the polyetheramine compound includes one or a combination of several of polyetheramine D400, polyetheramine D2000, polyetheramine D230 and polyetheramine T403.

[0011] Preferably, the antioxidant includes one or more of antioxidants 1010, antioxidant 1076, antioxidant 168, antioxidant 242 and antioxidant 626.

[0012] By adopting the above technical solutions, the fiber of the present invention has a core-sheath structure. Specifically, PET polyester is used as the core layer, which provides it with excellent rigidity and dimensional stability. At the same time, epoxy-based polysiloxane is compounded. The epoxy groups can react chemically with the hydroxyl or carboxyl groups at the end of the PET molecular chain, which can not only enhance the compatibility between the two, but also the flexible main chain of polysiloxane can weaken the tight packing between PET molecules and reduce the crystallinity. While maintaining the mechanical strength of the core layer, its softness is improved, and the effect of an overly hard core layer on the overall softness is avoided.

[0013] The outer layer uses poly(1,3-propylene terephthalate) (PTT). PTT molecular chains are soft and highly mobile, directly imparting a soft touch to the fiber surface. Its resilience is also close to that of cotton fibers, enhancing the cotton-like fluffiness. Furthermore, the outer layer contains a polyetheramine flexible polymer. This polymer is obtained by reacting rigid dianhydrides with polyetheramine, possessing both a rigid skeleton and a flexible polyether structure. The polyether structure exhibits excellent flexibility, further reducing the rigidity of the outer layer. Simultaneously, its polar amino groups enhance the hydrophilicity of the outer layer, mimicking the moisture absorption properties of cotton fibers. This further improves the softness and cotton-like effect of the PET polyester fiber, achieving the goal of ultra-soft PET polyester fiber.

[0014] The rigid backbone in polyetheramine flexible polymers serves two main purposes. First, it ensures the mechanical strength of PET polyester fibers. The rigid portion exhibits compatibility with the PTT matrix and acts as a reinforcing unit, helping to maintain the mechanical integrity of the skin layer and preventing a decrease in the mechanical strength of PET polyester fibers due to excessive addition of flexible components. Second, the rigid structure of polyetheramine flexible polymers mitigates the problem of easy hydrolysis of ester bonds in PTT under high-temperature processing conditions. Its imide ring structure possesses higher thermal and hydrolytic stability than ester bonds, acting as a stabilizing point during processing to effectively inhibit the thermal degradation and hydrolytic breakage of PTT molecular chains, ensuring the stability of the skin material's molecular weight and ultimately guaranteeing the quality of PET polyester fibers.

[0015] Preferably, the preparation method of the polyetheramine flexible polymer includes the following steps: The dianhydride compound and the polyetheramine compound are added to a solvent and reacted at 100–110 °C for 16–20 h to obtain the product.

[0016] Preferably, the solvent includes any one of ethylene glycol, propylene glycol, butanediol, dimethyl sulfoxide, and N,N-dimethylformamide.

[0017] By adopting the above technical solution, a flexible polyetheramine polymer is generated by sequentially undergoing ring-opening, acylation, and dehydration reactions of a dianhydride compound and a polyetheramine compound. Specifically, the amino group of the polyetheramine compound first attacks one of the anhydrides in the dianhydride compound, opening the anhydride ring and generating an amic acid intermediate; then the carboxyl and amide groups in the amic acid undergo intramolecular condensation, and after dehydration, the flexible polyetheramine polymer can be obtained.

[0018] Polyetheramine flexible polymers enhance flexibility and reduce sheath rigidity through the excellent polyether structure in the molecular chain. Its polar amino groups can also improve the hydrophilicity of the fiber to simulate the touch and moisture absorption properties of cotton fibers, thereby enhancing the overall soft, cotton-like effect. At the same time, its rigid skeleton derived from diacid anhydride is well compatible with the PTT sheath matrix and serves as a reinforcing unit to prevent the fiber mechanical strength from decreasing due to the addition of flexible components. Furthermore, the thermal stability and hydrolysis resistance of the rigid structure are better than those of ester bonds, which can effectively inhibit thermal degradation and hydrolytic breakage during PTT processing, ensure the molecular weight stability of the sheath material, and ensure fiber quality, thus achieving a synergistic unity of improved softness and performance stability.

[0019] Secondly, the present invention provides a production process for ultra-soft cotton-like polyester fiber, comprising the following steps: S1. Weigh 80-100 parts of polyethylene terephthalate chips, 10-20 parts of epoxy polysiloxane, and 0.5-2 parts of antioxidant according to the weight ratio, mix them evenly, and then melt and extrude to obtain the core layer melt. S2. Weigh 50-70 parts of 1,3-propylene terephthalate chips and 20-30 parts of polyetheramine flexible polymer according to the weight ratio, mix them evenly, and then melt and extrude to obtain the skin melt. S3. The core melt and the sheath melt are uniformly extruded and formed through the core-sheath composite spinning assembly, and then cooled, oiled and wound to obtain ultra-soft cotton-like polyester fiber.

[0020] Preferably, in step S1, the temperature of the melt extrusion is 260–270°C.

[0021] Preferably, in step S2, the temperature of the melt extrusion is 220–230°C.

[0022] Preferably, in step S3, the mass ratio of the core melt to the skin melt is 1:(1-3).

[0023] By employing the above technical solutions, the production of ultra-soft cotton-like polyester fibers is achieved by separately controlling the melting temperatures of the core layer and the sheath layer. The core layer temperature range of 260–270℃ not only ensures the complete melting of PET chips but also promotes the effective reaction between epoxy-based polysiloxanes and PET, permanently establishing the softness of PET through chemical bonding. The sheath layer temperature range of 220–230℃ matches the melting characteristics of PTT (polytetrafluoroethylene) and prevents hydrolysis of PTT ester bonds due to excessively high temperatures. Furthermore, the softness of the PET polyester fibers can be further controlled by adjusting the mass ratio of the core layer melt to the sheath melt.

[0024] The beneficial effects of this invention are: 1. The ultra-soft cotton-like polyester fiber of this invention utilizes a core-sheath composite structure design. PET serves as the core layer to ensure the mechanical strength of the PET polyester fiber. By introducing epoxy-based polysiloxanes into the core layer, a chemical reaction occurs with the end groups of PET, enhancing compatibility and reducing crystallinity, thus improving overall softness while maintaining fiber strength. Simultaneously, a blend of PTT and polyetheramine flexible polymers is used as the sheath layer, significantly improving the softness, resilience, and skin-friendly feel of the fiber surface, achieving a comfortable touch close to that of cotton fibers. The polyetheramine flexible polymer in the sheath layer contains both flexible polyether segments and a rigid skeleton, maintaining mechanical integrity and further improving fiber softness. It also improves the processing stability and hydrolysis resistance of PTT, ensuring structural stability during high-temperature spinning, ultimately resulting in an ultra-soft cotton-like polyester fiber.

[0025] 2. The production process of the ultra-soft cotton-like polyester fiber of the present invention controls the melting temperature of the core layer and the sheath layer in stages, adapts to the characteristics of different components to avoid the decline of polyester fiber performance, and the sheath-core composite spinning can flexibly adjust the sheath-core ratio to optimize the softness of polyester fiber. Detailed Implementation

[0026] The specific embodiments of the present invention will be described in detail below, but it should be understood that the scope of protection of the present invention is not limited to the specific embodiments.

[0027] Preparation Example

[0028] Preparation Example 1: A flexible polyetheramine polymer was prepared according to the following method: Cyclohexanetetracarboxylic dianhydride and polyetheramine T403 in a molar ratio of 1:1.4 were added to 30 mL of ethylene glycol solution, ultrasonically dispersed for 20 min, and reacted at 105 °C for 18 h under a nitrogen atmosphere to obtain a flexible polyetheramine polymer.

[0029] Preparation Example 2: A flexible polyetheramine polymer was prepared according to the following method: Cyclohexanetetracarboxylic dianhydride and polyetheramine T403 in a molar ratio of 1:5 were added to 30 mL of ethylene glycol solution, ultrasonically dispersed for 20 min, and reacted at 105 °C for 18 h under a nitrogen atmosphere to obtain a polyetheramine flexible polymer.

[0030] Preparation Example 3: A flexible polyetheramine polymer was prepared according to the following method: Cyclohexanetetracarboxylic dianhydride and polyetheramine T403 in a molar ratio of 1:0.8 were added to 30 mL of ethylene glycol solution, ultrasonically dispersed for 20 min, and reacted at 105 °C for 18 h under a nitrogen atmosphere to obtain a flexible polyetheramine polymer.

[0031] Example

[0032] Example 1: An ultra-soft cotton-like polyester fiber was prepared according to the following method: S1. Weigh 90 parts of polyethylene terephthalate chips, 15 parts of side-chain epoxy polysiloxane, and 1 part of antioxidant 1010 according to the weight ratio. Mix them evenly and then melt-extrude them at a temperature of 270℃ to obtain the core layer melt. S2. Weigh 60 parts of 1,3-propylene terephthalate chips and 25 parts of polyetheramine flexible polymer prepared in Preparation Example 1 according to the weight ratio. After mixing evenly, melt extrude the mixture at a temperature of 230°C to obtain the skin melt. S3. Core melt and sheath melt with a mass ratio of 1:2 are uniformly extruded and formed through a core-sheath composite spinning assembly. After cooling, oiling and winding, ultra-soft cotton-like polyester fiber is obtained.

[0033] Example 2: An ultra-soft cotton-like polyester fiber was prepared according to the following method: S1. Weigh 80 parts of polyethylene terephthalate chips, 10 parts of side-chain epoxy polysiloxane, and 0.5 parts of antioxidant 1010 according to the weight ratio. Mix them evenly and then melt-extrude them at a temperature of 270℃ to obtain the core layer melt. S2. Weigh 50 parts of 1,3-propylene terephthalate chips and 20 parts of polyetheramine flexible polymer prepared in Preparation Example 1 according to the weight ratio. After mixing evenly, melt extrude at a temperature of 230°C to obtain the skin melt. S3. Core melt and sheath melt with a mass ratio of 1:2 are uniformly extruded and formed through a core-sheath composite spinning assembly. After cooling, oiling and winding, ultra-soft cotton-like polyester fiber is obtained.

[0034] Example 3: An ultra-soft cotton-like polyester fiber was prepared according to the following method: S1. Weigh 100 parts of polyethylene terephthalate chips, 20 parts of side-chain epoxy polysiloxane, and 2 parts of antioxidant 1010 according to the weight ratio. Mix them evenly and then melt-extrude them at a temperature of 270℃ to obtain the core layer melt. S2. Weigh 70 parts of 1,3-propylene terephthalate chips and 30 parts of polyetheramine flexible polymer prepared in Preparation Example 1 according to the weight ratio. After mixing evenly, melt extrude the mixture at a temperature of 230°C to obtain the skin melt. S3. Core melt and sheath melt with a mass ratio of 1:2 are uniformly extruded and formed through a core-sheath composite spinning assembly. After cooling, oiling and winding, ultra-soft cotton-like polyester fiber is obtained.

[0035] Example 4: An ultra-soft cotton-like polyester fiber, which differs from Example 1 only in that the mass ratio of the core melt and the skin melt in step S3 is 1:5.

[0036] Example 5: An ultra-soft cotton-like polyester fiber, which differs from Example 1 only in that the mass ratio of the core melt and the skin melt in step S3 is 1:0.5.

[0037] Comparative Example

[0038] Comparative Example 1: An ultra-soft cotton-like polyester fiber was prepared according to the following method: S1. Weigh 90 parts of polyethylene terephthalate chips, 5 parts of side-chain epoxy polysiloxane, and 1 part of antioxidant 1010 according to the weight ratio. Mix them evenly and then melt-extrude them at a temperature of 270℃ to obtain the core layer melt. S2. Weigh 40 parts of 1,3-propylene terephthalate chips and 25 parts of polyetheramine flexible polymer prepared in Preparation Example 1 according to the weight ratio. After mixing evenly, melt extrude the mixture at a temperature of 230°C to obtain the skin melt. S3. Core melt and sheath melt with a mass ratio of 1:2 are uniformly extruded and formed through a core-sheath composite spinning assembly. After cooling, oiling and winding, ultra-soft cotton-like polyester fiber is obtained.

[0039] Comparative Example 2: An ultra-soft cotton-like polyester fiber was prepared according to the following method: S1. Weigh 90 parts of polyethylene terephthalate chips, 25 parts of side-chain epoxy polysiloxane, and 1 part of antioxidant 1010 according to the weight ratio. Mix them evenly and then melt-extrude them at a temperature of 270℃ to obtain the core layer melt. S2. Weigh 80 parts of 1,3-propylene terephthalate chips and 25 parts of polyetheramine flexible polymer prepared in Preparation Example 1 according to the weight ratio. After mixing evenly, melt extrude the mixture at a temperature of 230°C to obtain the skin melt. S3. Core melt and sheath melt with a mass ratio of 1:2 are uniformly extruded and formed through a core-sheath composite spinning assembly. After cooling, oiling and winding, ultra-soft cotton-like polyester fiber is obtained.

[0040] Comparative Example 3 is an ultra-soft cotton-like polyester fiber, which differs from Example 1 only in that the amount of polyetheramine flexible polymer added is 10 parts.

[0041] Comparative Example 4: An ultra-soft cotton-like polyester fiber, which differs from Example 1 only in that the amount of polyetheramine flexible polymer added is 35 parts.

[0042] Comparative Example 5: An ultra-soft cotton-like polyester fiber, which differs from Example 1 only in that it does not contain epoxy polysiloxane.

[0043] Comparative Example 6: An ultra-soft cotton-like polyester fiber, which differs from Example 1 only in that the polyetheramine flexible polymer prepared in Preparation Example 2 is replaced with the same amount of polyetheramine flexible polymer prepared in Preparation Example 1.

[0044] Comparative Example 7, an ultra-soft cotton-like polyester fiber, differs from Example 1 only in that the polyetheramine flexible polymer prepared in Preparation Example 3 is replaced with the same amount of polyetheramine flexible polymer prepared in Preparation Example 1.

[0045] Comparative Example 8 is an ultra-soft cotton-like polyester fiber, which differs from Example 1 only in that it does not contain polyetheramine flexible polymer.

[0046] Comparative Example 9: An ultra-soft cotton-like polyester fiber was prepared according to the following method: 90 parts by weight of polyethylene terephthalate chips, 25 parts by weight of side-chain epoxy polysiloxane, 1 part by weight of antioxidant 1010, 80 parts by weight of 1,3-propylene terephthalate chips, and 35 parts by weight of polyetheramine flexible polymer prepared in Preparation Example 1 were weighed and mixed evenly. The mixture was then melt-extruded at a temperature of 270°C. After cooling, oiling, and winding, ultra-soft cotton-like polyester fiber was obtained.

[0047] Performance testing

[0048] 1. Softness test: The softness of the ultra-soft cotton-like polyester fibers prepared in Examples 1 to 5 and Comparative Examples 1 to 9 was tested on a fabric softness tester in accordance with GB / T 41567-2022. Representative samples with dimensions of (100±2) mm × (100±2) mm were taken parallel to the warp (direction) and weft (transverse) directions. The test results are shown in Table 1.

[0049] 2. Curl shrinkage rate test: The ultra-soft cotton-like polyester fibers prepared in Examples 1 to 5 and Comparative Examples 1 to 9 were tested according to the method described in GB / T 6506-2017, and the test results are shown in Table 1.

[0050] 3. Mechanical property testing: The ultra-soft cotton-like polyester fibers prepared in Examples 1 to 5 and Comparative Examples 1 to 9 were tested according to the standard GB / T 14337-2022, and the test results are shown in Table 1.

[0051] Table 1

[0052] According to Table 1, and in conjunction with Examples 1 and 4-5, it can be seen that the softness and curl shrinkage rate of Examples 4-5 are lower than those of Example 1, the breaking strength of Example 4 is lower than that of Example 1, while the breaking strength of Example 5 is slightly higher than that of Example 1. The reason for this is that the difference between Example 4 and Example 1 is that the mass ratio of core melt to sheath melt in Example 4 is 1:5. When too much sheath melt is added, the proportion of PTT and polyetheramine flexible polymer in the sheath on the fiber surface is too high. Although this improves the softness and curl shrinkage rate to a certain extent, the supporting effect of the core layer is weakened, resulting in a decrease in breaking strength. The difference between Example 5 and Example 1 is that the mass ratio of core melt to sheath melt in Example 5 is 1:0.5. When too little sheath melt is added, the surface flexible component is insufficient and cannot effectively cover the rigidity of the core layer, resulting in a decrease in softness and curl shrinkage rate. However, the proportion of PET in the core layer is higher, which enhances the breaking strength.

[0053] Combining Example 1 and Comparative Example 5, it can be seen that the softness and curl shrinkage rate of Comparative Example 5 are significantly lower than those of Example 1, while the breaking strength is slightly lower than that of Example 1. The reason for this is that the difference between Comparative Example 5 and Example 1 is that Comparative Example 5 does not contain epoxy-based polysiloxane. On the one hand, PET lacks the grafting reaction of epoxy groups, so the tightly packed structure between PET molecules is not weakened, resulting in high crystallinity and strong rigidity, which leads to a significant increase in warp softness. On the other hand, without the regulation of polyetheramine flexible polymers with polysiloxane, the core layer is not flexible enough, the shrinkage synergy between the skin layer and the core layer is poor, and the curl shrinkage rate is reduced.

[0054] Based on Example 1 and Comparative Examples 6-7, it can be seen that the flexibility, curl shrinkage rate, and breaking strength of Comparative Examples 6-7 are all lower than those of Example 1. The reason for this is that the difference between Comparative Example 6 and Example 1 is that the molar ratio of dianhydride compound to polyetheramine compound in the polyetheramine flexible polymer of Comparative Example 6 is 1:5. When too much polyetheramine compound is added, the proportion of polyether chains in the polyetheramine flexible polymer is too high. Although it has a certain degree of flexibility, the excessive flexible chains are prone to entanglement, resulting in insufficient cohesion in the skin layer. Furthermore, the compatibility with PTT decreases, and local breakage is likely to occur under stress, leading to a decrease in breaking strength and limited improvement in flexibility. The difference between Comparative Example 7 and Example 1 is that the molar ratio of dianhydride compound to polyetheramine compound in Comparative Example 7 is 1:0.8. When too little polyetheramine compound is added, the excessive dianhydride leads to an excessively high proportion of rigid skeleton in the polyetheramine flexible polymer, insufficient chain segment flexibility, increased skin layer rigidity, and a significant decrease in flexibility and curl shrinkage rate.

[0055] Combining Example 1 and Comparative Example 8, it can be seen that the softness and curling shrinkage rate of Comparative Example 8 are significantly lower than those of Example 1, while the breaking strength is higher than that of Example 1. The reason is that the difference between Comparative Example 8 and Example 1 is that Comparative Example 8 does not add polyetheramine flexible polymer. The skin layer only relies on PTT to provide softness. It lacks the synergistic softening effect of polyether chains in polyetheramine flexible polymer, which increases surface rigidity and significantly reduces softness and curling shrinkage rate. At the same time, the breaking strength is enhanced without the weakening effect of polyetheramine flexible polymer.

[0056] Combining Example 1 and Comparative Example 9, it can be seen that the softness and curl shrinkage rate of Comparative Example 9 are significantly lower than those of Example 1, while the breaking strength is lower than that of Example 1. The reason is that the difference between Comparative Example 9 and Example 1 is that Comparative Example 9 does not use a core-sheath structure. After the components are simply blended, PTT and polyetheramine flexible polymer cannot form a continuous flexible layer on the PET surface, and the effect of improving softness is weakened. At the same time, the functional partitioning between the core layer and the skin layer disappears, and there is a lack of stress difference driving during curl shrinkage, resulting in a reduced shrinkage rate. In addition, the uneven dispersion of the components easily leads to stress concentration, resulting in a decrease in breaking strength.

[0057] The above-disclosed embodiments are merely a few specific examples of the present invention. However, the embodiments of the present invention are not limited thereto, and any variations that can be conceived by those skilled in the art should fall within the protection scope of the present invention.

Claims

1. An ultra-soft cotton-like polyester fiber, characterized in that, Including the core layer and the skin layer; The core layer comprises the following components in parts by weight: 80-100 parts of polyethylene terephthalate chips, 10-20 parts of epoxy-based polysiloxane, and 0.5-2 parts of antioxidant; The dermis comprises the following components in parts by weight: 50-70 parts of 1,3-propylene terephthalate chips and 20-30 parts of polyetheramine flexible polymer; The raw materials for the polyetheramine flexible polymer include dianhydride compounds and polyetheramine compounds in a molar ratio of 1:(1.2-4).

2. The ultra-soft cotton-like polyester fiber according to claim 1, characterized in that, The epoxy-based polysiloxane includes one or a combination of two of side-chain epoxy-based polysiloxanes and terminal-chain epoxy-based polysiloxanes.

3. The ultra-soft cotton-like polyester fiber according to claim 1, characterized in that, The dianhydride compound includes one or more of cyclohexanetetracarboxylic dianhydride, ethylenediaminetetraacetic dianhydride, naphthalenetetracarboxylic dianhydride, biphenyltetracarboxylic dianhydride, and pyromellitic dianhydride.

4. The ultra-soft cotton-like polyester fiber according to claim 1, characterized in that, The polyetheramine compound includes one or more of polyetheramine D400, polyetheramine D2000, polyetheramine D230 and polyetheramine T403.

5. The ultra-soft cotton-like polyester fiber according to claim 1, characterized in that, The preparation method of the polyetheramine flexible polymer includes the following steps: The dianhydride compound and the polyetheramine compound are added to a solvent and reacted at 100–110 °C for 16–20 h to obtain the product.

6. The ultra-soft cotton-like polyester fiber according to claim 1, characterized in that, The antioxidants include one or more of antioxidants 1010, 1076, 168, 242 and 626.

7. A production process for ultra-soft cotton-like polyester fiber, using the ultra-soft cotton-like polyester fiber as described in any one of claims 1-6, characterized in that, Includes the following steps: S1. Weigh 80-100 parts of polyethylene terephthalate chips, 10-20 parts of epoxy polysiloxane, and 0.5-2 parts of antioxidant according to the weight ratio, mix them evenly, and then melt-extrude them to obtain the core layer melt. S2. Weigh 50-70 parts of 1,3-propylene terephthalate chips and 20-30 parts of polyetheramine flexible polymer according to the weight ratio, mix them evenly and then melt extrude to obtain the skin melt. S3. The core melt and the sheath melt are uniformly extruded and formed through the core-sheath composite spinning assembly, and then cooled, oiled and wound to obtain ultra-soft cotton-like polyester fiber.

8. The production process of an ultra-soft cotton-like polyester fiber according to claim 7, characterized in that, In step S1, the temperature of the melt extrusion is 260–270°C.

9. The production process of an ultra-soft cotton-like polyester fiber according to claim 7, characterized in that, In step S2, the temperature of the melt extrusion is 220–230°C.

10. The production process of an ultra-soft cotton-like polyester fiber according to claim 7, characterized in that, In step S3, the mass ratio of the core melt to the skin melt is 1:(1-3).

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