A sheath-core composite fiber with cool touch and high dyeability and preparation method thereof

Abstract

The present invention relates to the field of functional fibers and discloses a sheath-core composite fiber with a cool feel and high dyeability, and a method for preparing the same. The sheath-core composite fiber comprises a polyethylene-based sheath layer and a core layer made of a hygroscopic, dyeable polyester. The sheath-core composite fiber of the present invention utilizes a polyethylene-based sheath layer and a hygroscopic, dyeable polyester core layer, achieving a superior cool feel and high dyeability.

Description

Technical Field

[0001] The present invention relates to the field of functional fibers, in particular to a core-sheath composite fiber with a cool touch feeling and high dyeability and a preparation method thereof. Background Art

[0002] With the development of science and technology, the development and use of functional fibers have become one of the important trends in the development of textiles in the future. Cooling fibers, as an important functionalized fiber, are widely used in the fields of shirts, casual wear, bedding, etc., and are increasingly well received by consumers. At present, the way to give fabrics a cool touch feeling mainly includes the selection and design of raw materials and fabric structure, and the use of functional additives to post-treat the fabric. In the selection of raw materials, polyethylene (especially ultra-high molecular weight polyethylene and high-density polyethylene) has a higher thermal conductivity and can give fibers a better cool feeling, but it has the disadvantage of poor dyeability.

[0003] The patent application number CN202110918820.9 discloses a method for preparing a warp knitted fabric with moisture absorption, quick drying and cooling function and its product, wherein a hyperbranched polymer formed by polymerization of propylene glycol and terephthalic acid is added to polyethylene fiber to improve the dyeability of polyethylene fiber. However, in the fibers prepared by this doping method, the hyperbranched polymer is distributed inside the polyethylene matrix, and the polyethylene affects the diffusion of the dye to the hyperbranched polymer, so the improvement effect on the dyeability is limited. Although the dyeability can be improved by increasing the amount of hyperbranched polymer added, the cool touch feeling of the fiber will be affected. Summary of the Invention

[0004] To address the technical issue of poor dyeability in existing polyethylene-based cooling fibers, the present invention provides a sheath-core composite fiber with both a cool contact feel and high dyeability. This sheath-core composite fiber utilizes polyethylene and a hygroscopic, dyeable polyester as its sheath and core, respectively, achieving both a good cool contact feel and excellent dyeability. The specific technical solutions of the present invention are as follows: In a first aspect, the present invention provides a sheath-core composite fiber comprising a polyethylene-based sheath and a hygroscopic, dyeable polyester core.

[0005] In the core-sheath composite fiber of the present invention, the cortex is made of polyethylene, which has a high thermal conductivity and can produce a cool touch feeling, making the fabric feel smooth and smooth, while also having antibacterial and mildew-proof functions. Since polyethylene has a melting point of 130°C, is not resistant to high temperatures, and has poor hygroscopicity, the fiber prepared with this material has the problem of difficulty in dyeing. To this end, the present invention adopts a hygroscopic dyeable polyester material as the core layer, which can give the core-sheath composite fiber better moisture absorption and perspiration performance, thereby improving the cool feeling to a certain extent, and at the same time giving the fiber better dyeability, not only can cationic dyeing be achieved, but also disperse dyeing with a wider range of applications and a cheaper price can be achieved. In addition, the use of a hygroscopic dyeable polyester material as the core layer can also give the core-sheath composite fiber higher softness, so that the fabric made of the fiber has better softness and skin-friendly properties, making it more suitable for application in clothing and home textile products.

[0006] Preferably, the hygroscopic dyeable polyester is copolymerized by terephthalic acid, ethylene glycol and a modified monomer; the modified monomer includes one or more of a dibasic acid monomer, a diol monomer and an alkyd monomer (i.e., a monomer containing both an alcoholic hydroxyl group and a carboxyl group in the molecule); the dibasic acid monomer includes isophthalic acid and / or isophthalic acid sulfonate; the diol monomer includes one or more of neopentyl glycol, 1,3-butanediol, polyether diol and polytetramethylene glycol; and the alkyd monomer includes polyglycolic acid.

[0007] When preparing polyester, the introduction of isophthalic acid, isophthalic acid sulfonate, 1,3-butanediol, and neopentyl glycol with meta structures can disrupt the regularity and crystallinity of the polyethylene terephthalate molecular chain, increasing the amorphous region and facilitating the penetration of dye molecules into the amorphous regions of the fiber. The introduction of polyether diols, polytetramethylene glycol, and polyglycolic acid can lower the glass transition temperature (Tg) of the macromolecular chain, increasing the mobility of the macromolecular segments, allowing dyes to enter the fiber at lower temperatures, achieving low-temperature dyeing. Furthermore, the introduction of these polymer segments can increase the hygroscopicity of the core layer, enabling the fiber to be dyed in darker colors. Furthermore, isophthalic acid can improve the fiber's dyeability with disperse dyes, while isophthalic acid sulfonate can improve the fiber's dyeability with cationic dyes. Furthermore, the introduction of polyglycolic acid, in addition to the introduction of meta-structured dibasic acids or alcohols and the flexible polyether diol, can not only further enhance the fiber's strength but also make the easily dyeable polyester biodegradable.

[0008] Preferably, the method for preparing the hygroscopic dyeable polyester comprises the following steps:

[0009] (1.1) Esterifying terephthalic acid, ethylene glycol, and a dibasic acid monomer to obtain an esterified product;

[0010] (1.2) The esterified product is mixed with a diol monomer and / or an alkyd monomer, and subjected to preliminary polycondensation and final polycondensation to obtain a hygroscopic dyeable polyester.

[0011] Preferably, in the terephthalic acid, ethylene glycol and modified monomer, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.15-1.4:1.

[0012] Preferably, in step (1.1), the esterification reaction is carried out in the presence of a catalyst at a temperature of 225-245° C., a pressure of 0.1-0.3 MPa, and a time of 1.5-2.5 h.

[0013] Preferably, in step (1.1), the esterification rate is controlled to be above 85%.

[0014] Preferably, in step (1.2), the temperature of the pre-polycondensation is 255-265° C., the pressure is 50-150 Pa, and the time is 40-60 min; the temperature of the final polycondensation is 265-278° C., the pressure is 100-120 Pa, and the time is 1-2 h.

[0015] Preferably, the dibasic acid monomer is used in an amount of 2.5-5.5 mol% of terephthalic acid.

[0016] Preferably, the amount of the neopentyl glycol and 1,3-butanediol used is 3-9 mol% of terephthalic acid.

[0017] Preferably, the polyether glycol, polytetrahydrofuran diol and polyglycolic acid are used in an amount of 2-6wt% of the hygroscopic dyeable polyester.

[0018] Preferably, the number average molecular weight of the polyether diol is 1000-8000 Da.

[0019] Preferably, the number-average molecular weight of the polytetrahydrofuran diol is 1000-6000Da.

[0020] Preferably, the material of the skin layer is a mixture of graphene masterbatch and polyethylene, and the amount of graphene masterbatch is 5-6wt% of the polyethylene.

[0021] Preferably, the density of the polyethylene is 0.94-0.96 g / cm 3 , the melt index is 17-25g / 10min.

[0022] Preferably, the filter pressure difference of the graphene masterbatch is not higher than 1.6 MPa.

[0023] Preferably, the skin layer forms a structure partially enclosing the core layer outside the core layer, and the arc length of the exposed portion of the core layer accounts for 5-20% of the circumference of the entire cross-section of the skin-core composite fiber.

[0024] The partial encapsulation structure between the skin layer and the core layer can avoid the problem of dyeing stripes on the fabric. At the same time, this structure can also improve the moisture absorption and perspiration performance of the fiber, thereby further improving its cool touch feeling.

[0025] Preferably, the mass ratio of the skin layer to the core layer is 35-70:65-30.

[0026] Preferably, the polyether diol is polyethylene glycol and / or a double-terminal hydroxyl block copolyether consisting of polyethylene oxide segments and poly-2,3-butylene oxide segments.

[0027] When a double-terminated hydroxyl block copolyether composed of polyethylene oxide segments and poly(2,3-butylene oxide) segments is used as a modifying monomer in a hygroscopic dyeable polyester, the polyethylene oxide segments possess high hydrophilicity, while the poly(2,3-butylene oxide) segments effectively disrupt the regularity of the polyethylene terephthalate molecular chain, reducing its crystallinity. The two segments are interconnected and can better cooperate with each other, further promoting the absorption, diffusion, and binding of dye molecules in the hygroscopic dyeable polyester, thereby improving the dyeability of the core-skin composite fiber. Furthermore, compared to polyethylene oxide segments, this can also make the hygroscopic dyeable polyester more stable during the spinning process, resulting in higher strength for the core-skin composite fiber.

[0028] Preferably, the preparation method of the dihydroxy-terminated block copolyether comprises the following steps: mixing ethylene glycol and potassium hydroxide in a mass ratio of 1:0.35-0.38, adding ethylene oxide in a molar amount of 17.8-19.0 times that of ethylene glycol under the protection of inert gas, reacting at 110-120°C and 0.2-0.3Mpa for 3-3.5 hours, then adding 2,3-butylene oxide in a molar amount of 1.7-1.9 times that of ethylene glycol, and continuing to react at 110-120°C and 0.2-0.3Mpa for 2-2.5 hours to obtain the dihydroxy-terminated block copolyether.

[0029] During the preparation of double-terminated hydroxyl block copolyethers, the amounts of ethylene oxide and 2,3-butylene oxide, as well as the reaction time, affect the content of both polyethylene oxide and poly(2,3-butylene oxide) segments in the resulting copolyether. When the relative content of polyethylene oxide segments in the copolyether is too high, the resulting hygroscopic, dyeable polyester can become sticky and unstable during the spinning process, resulting in lower strength for the core-sheath composite fiber. When the relative content of poly(2,3-butylene oxide) segments in the copolyether is too high, the hydrophilicity of the polyetheramine is reduced to a certain extent, resulting in poor dyeability for the core-sheath composite fiber. Based on this, the present invention controls the amounts of ethylene oxide and 2,3-butylene oxide and the reaction time within the aforementioned specific ranges, enabling the copolyether to significantly improve the dyeability of the core-sheath composite fiber and impart higher strength to the core-sheath composite fiber.

[0030] In a second aspect, the present invention provides a method for preparing the sheath-core composite fiber, comprising the following steps: continuously crystallizing and drying the sheath material and the core material to make a sheath dry material and a core dry material, and then performing sheath-core composite spinning to obtain the sheath-core composite fiber.

[0031] Preferably, the moisture content of the skin layer dry material is less than 300 ppm, and the moisture content of the core layer dry material is less than 30 ppm.

[0032] Preferably, the specific process of the sheath-core composite spinning includes the following steps: the sheath material and the core material are transported to the spinning box through a screw, passed through a pre-filter, and evenly distributed to the sheath-core composite component for spinning, wherein the box temperature of the core layer part is 263-270°C, and the box temperature of the sheath part is 232-240°C, followed by ring cooling heating, side blowing, and oiling, and then winding at 3000-3500m / min to obtain the sheath-core composite fiber.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] (1) The sheath-core composite fiber of the present invention uses a polyethylene-based material as the sheath layer and a hygroscopic dyeable polyester material as the core layer, which can achieve a good touch cool feeling and also has good dyeability;

[0035] (2) In the core layer of the present invention, by using a specific modified monomer to participate in the copolymerization of terephthalic acid and ethylene glycol, the dyeability of the core-skin composite fiber can be improved, and low-temperature dyeing of dark colors can be achieved. DETAILED DESCRIPTION

[0036] The present invention will be further described below with reference to the embodiments.

[0037] The following description of the embodiments is intended to facilitate understanding and use of the invention by those skilled in the art. It will be apparent to those skilled in the art that various modifications to these embodiments can be readily made and that the general principles described herein can be applied to other embodiments without requiring inventive effort. Therefore, the present invention is not limited to the following embodiments. Improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be considered within the scope of protection of the present invention.

[0038] Overall embodiment

[0039] A sheath-core composite fiber with a cool touch and high dyeability comprises a sheath layer and a core layer; the sheath layer is a polyethylene-based sheath layer; and the core layer is made of hygroscopic dyeable polyester.

[0040] As a specific embodiment, the hygroscopic dyeable polyester is copolymerized by terephthalic acid, ethylene glycol and a modified monomer; the modified monomer includes one or more of a dibasic acid monomer, a diol monomer and an alkyd monomer; the dibasic acid monomer includes isophthalic acid and / or isophthalic acid sulfonate; the diol monomer includes one or more of neopentyl glycol, 1,3-butanediol, polyether diol and polytetramethylene glycol; the alkyd monomer includes polyglycolic acid.

[0041] As a specific embodiment, in the terephthalic acid, ethylene glycol and modified monomer, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.15-1.4:1.

[0042] As a specific embodiment, the amount of the dibasic acid monomer is 2.5-5.5 mol% of terephthalic acid; the amount of the neopentyl glycol and 1,3-butanediol is 3-9 mol% of terephthalic acid; the amount of the polyether diol, polytetramethylene glycol and polyglycolic acid is 2-6 wt% of the hygroscopic dyeable polyester.

[0043] As a specific embodiment, the number average molecular weight of the polyether diol is 1000-8000Da; the number average molecular weight of the polytetrahydrofuran diol is 1000-6000Da.

[0044] As a specific embodiment, the preparation method of the hygroscopic dyeable polyester comprises the following steps:

[0045] (1.1) Esterification of terephthalic acid, ethylene glycol, and dibasic acid monomers in the presence of a catalyst at a temperature of 225-245°C, a pressure of 0.1-0.3 MPa, and a reaction time of 1.5-2.5 hours to obtain an esterified product with an esterification rate of more than 85%;

[0046] (1.2) The esterified product is mixed with a diol monomer and / or an alkyd monomer, pre-polycondensed at 255-265° C. and a pressure of 50-150 Pa for 40-60 min, and then final polycondensed at 265-278° C. and a pressure of 100-120 Pa for 1-2 h to obtain a hygroscopic dyeable polyester.

[0047] As a specific embodiment, the material of the skin layer is a mixture of graphene masterbatch and polyethylene, the amount of graphene masterbatch is 5-6wt% of polyethylene; the density of the polyethylene is 0.94-0.96g / cm 3 , the melt index is 17-25g / 10min; the filter pressure difference of the graphene masterbatch is not higher than 1.6Mpa.

[0048] As a specific embodiment, the skin layer forms a structure that partially encloses the core layer outside the core layer, and the arc length of the exposed part of the core layer accounts for 5-20% of the circumference of the entire cross-section of the skin-core composite fiber.

[0049] As a specific implementation manner, the mass ratio of the skin layer to the core layer is 35-70:65-30.

[0050] In a specific embodiment, the polyether diol is polyethylene glycol and / or a bihydroxyl-terminated block copolyether composed of polyethylene oxide segments and poly-2,3-butylene oxide segments. The preparation method of the bihydroxyl-terminated block copolyether comprises the following steps: mixing ethylene glycol and potassium hydroxide at a mass ratio of 1:0.35-0.38, adding ethylene oxide at a molar weight of 17.8-19.0 times that of ethylene glycol under inert gas protection, reacting at 110-120°C and 0.2-0.3 MPa for 3-3.5 hours, then adding 2,3-butylene oxide at a molar weight of 1.7-1.9 times that of ethylene glycol, and continuing to react at 110-120°C and 0.2-0.3 MPa for 2-2.5 hours to produce the bihydroxyl-terminated block copolyether.

[0051] A preparation method of the sheath-core composite fiber comprises the following steps: continuously crystallizing and drying the sheath material and the core material to prepare the sheath dry material and the core dry material, and then performing sheath-core composite spinning to obtain the sheath-core composite fiber.

[0052] As a specific implementation manner, the moisture content of the skin layer dry material is less than 300 ppm, and the moisture content of the core layer dry material is less than 30 ppm.

[0053] As a specific embodiment, the specific process of the sheath-core composite spinning includes the following steps: the sheath material and the core material are transported to the spinning box through a screw, passed through a pre-filter, and evenly distributed to the sheath-core composite component for spinning, wherein the box temperature of the core layer part is 263-270°C, and the box temperature of the sheath part is 232-240°C, followed by ring cooling heating, side blowing, and oiling, and then winding at 3000-3500m / min to obtain the sheath-core composite fiber.

[0054] Example 1

[0055] A sheath-core composite fiber is prepared by the following steps:

[0056] (1) Preparation of hygroscopic dyeable polyester:

[0057] (1.1) Terephthalic acid, ethylene glycol, isophthalic acid, and the catalyst antimony glycolate are mixed by beating at room temperature, and an esterification reaction is carried out at 225-245°C and 0.1-0.3 MPa pressure (initial value is 230°C and 0.16 MPa) for about 2 hours, with the esterification rate controlled at 90%, to obtain an esterified product; the amount of antimony glycolate added is 400 ppm of the theoretical polyester production;

[0058] (1.2) Polyethylene glycol 2000 is added to the esterified product, followed by a pre-condensation reaction at 255-265°C and a pressure of 50-150 Pa (initial value is 260°C and 50 Pa) for 60 minutes; a final condensation reaction is carried out at 265-278°C and a pressure of 100-120 Pa (initial value is 265°C and 100 Pa) for 1-2 hours, and when the current reaches the requirement, the material is pelletized and discharged to obtain hygroscopic dyeable polyester pellets; in terephthalic acid, ethylene glycol, isophthalic acid and polyethylene glycol 2000, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.2:1, wherein the amount of terephthalic acid is 400 mol, the amount of isophthalic acid is 5 mol% of terephthalic acid, and the amount of polyethylene glycol 2000 is 4wt% of the hygroscopic dyeable polyester.

[0059] (2) Preparation of enhanced PE

[0060] Graphene masterbatch (purchased from Zhushengfu Nanotechnology, with a filter pressure difference of 1.2 MPa) was added to polyethylene (density 96 g / cm 3 , melt index is 20g / 10min), the amount of graphene masterbatch is 5wt% of polyethylene, and the reinforced PE pellets are prepared by a twin-screw granulation process, the twin-screw barrel temperature is 240°C, and the twin-screw main engine speed is 500r / min.

[0061] (3) Skin-core composite spinning:

[0062] Reinforced PE pellets were dried at 80°C for 15 hours, achieving a moisture content of <300ppm. Hygroscopic dyeable polyester pellets were dried at 125°C for 18 hours, achieving a moisture content of <30ppm. The reinforced PE as the sheath and the hygroscopic dyeable polyester as the core were conveyed by a screw into a spinning manifold, passed through a pre-filter, and evenly distributed into a sheath-core composite fiber assembly. A C-shaped spinneret was used for sheath-core composite spinning, with the sheath partially enveloping the core. The exposed core portion accounted for 10% of the total sheath-core composite fiber cross-sectional circumference. During the sheath-core composite spinning process, the core portion was maintained at a box temperature of 265°C, while the sheath portion was maintained at 235°C. Subsequently, the fiber was subjected to annular cooling, side-blowing, and oiling. Finally, the fiber was wound at 3500 m / min to produce a sheath-core composite fiber with a fineness of 75D and a sheath-core mass ratio of 35:65.

[0063] Example 2

[0064] A sheath-core composite fiber is prepared by the following steps:

[0065] (1) Preparation of hygroscopic dyeable polyester:

[0066] (1.1) Terephthalic acid, ethylene glycol, 5-sodium sulfoisophthalate, and the catalyst antimony glycolate are mixed by beating at room temperature, and an esterification reaction is carried out at 225-245°C and 0.1-0.3 MPa pressure (initial value is 230°C and 0.16 MPa) for about 2 hours, with the esterification rate controlled at 90%, to obtain an esterified product; the amount of antimony glycolate added is 400 ppm of the theoretical polyester production;

[0067] (1.2) Polyethylene glycol 2000 is added to the esterified product, followed by a pre-condensation reaction at 255-265°C and a pressure of 50-150 Pa (initial value is 260°C and 50 Pa) for 60 minutes; a final condensation reaction is carried out at 265-278°C and a pressure of 100-120 Pa (initial value is 265°C and 100 Pa) for 1-2 hours, and when the current reaches the requirement, the material is pelletized and discharged to obtain hygroscopic dyeable polyester pellets; in terephthalic acid, ethylene glycol, sodium 5-sulfonate isophthalate and polyethylene glycol 2000, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.2:1, wherein the amount of terephthalic acid is 400 mol, the amount of sodium 5-sulfonate isophthalate is 5 mol% of terephthalic acid, and the amount of polyethylene glycol 2000 is 4wt% of the modified copolyester.

[0068] (2) Preparation of enhanced PE:

[0069] Graphene masterbatch (purchased from Zhushengfu Nanotechnology, with a filter pressure difference of 1.2 MPa) was added to polyethylene (density 0.96 g / cm 3, melt index is 20g / 10min), the amount of graphene masterbatch is 6wt% of polyethylene, and the reinforced PE pellets are prepared by a twin-screw granulation process, the twin-screw barrel temperature is 240°C, and the twin-screw main engine speed is 500r / min.

[0070] (3) Skin-core composite spinning:

[0071] Reinforced PE pellets were dried at 80°C for 15 hours, achieving a moisture content of <300ppm. Hygroscopic dyeable polyester pellets were dried at 125°C for 18 hours, achieving a moisture content of <30ppm. The reinforced PE as the sheath and the hygroscopic dyeable polyester as the core were conveyed by a screw into a spinning manifold, passed through a pre-filter, and evenly distributed into a sheath-core composite fiber assembly. A C-shaped spinneret was used for sheath-core composite spinning, with the sheath partially enveloping the core. The exposed core portion accounted for 10% of the total sheath-core composite fiber cross-sectional circumference. During the sheath-core composite spinning process, the core portion was maintained at a box temperature of 265°C, while the sheath portion was maintained at 235°C. Subsequently, the fiber was subjected to annular cooling, side-blowing, and oiling. Finally, the fiber was wound at 3500 m / min to produce a sheath-core composite fiber with a fineness of 75D and a sheath-core mass ratio of 35:65.

[0072] Example 3

[0073] A sheath-core composite fiber is prepared by the following steps:

[0074] (1) Preparation of hygroscopic dyeable polyester:

[0075] (1.1) Terephthalic acid, ethylene glycol, isophthalic acid, and the catalyst antimony glycolate are mixed by beating at room temperature, and an esterification reaction is carried out at 225-245°C and 0.1-0.3 MPa pressure (initial value is 230°C and 0.16 MPa) for about 2 hours, with the esterification rate controlled at 90%, to obtain an esterified product; the amount of antimony glycolate added is 400 ppm of the theoretical polyester production;

[0076] (1.2) Polyethylene glycol 2000 is added to the esterified product, followed by a pre-condensation reaction at 255-265°C and a pressure of 50-150 Pa (initial value is 260°C and 50 Pa) for 60 minutes; a final condensation reaction is carried out at 265-278°C and a pressure of 100-120 Pa (initial value is 265°C and 100 Pa) for 1-2 hours, and when the current reaches the requirement, the material is pelletized and discharged to obtain hygroscopic dyeable polyester pellets; in terephthalic acid, ethylene glycol, isophthalic acid and polyethylene glycol 2000, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.2:1, wherein the amount of terephthalic acid is 400 mol, the amount of isophthalic acid is 5 mol% of terephthalic acid, and the amount of polyethylene glycol 2000 is 4wt% of the hygroscopic dyeable polyester.

[0077] (2) Preparation of enhanced PE:

[0078] Graphene masterbatch (purchased from Zhushengfu Nanotechnology, with a filter pressure difference of 1.2 MPa) was added to polyethylene (density 0.96 g / cm 3 , melt index is 20g / 10min), the amount of graphene masterbatch is 6wt% of polyethylene, and the reinforced PE pellets are prepared by a twin-screw granulation process, the twin-screw barrel temperature is 240°C, and the twin-screw main engine speed is 500r / min.

[0079] (3) Skin-core composite spinning:

[0080] Reinforced PE pellets were dried at 80°C for 15 hours, achieving a moisture content of <300ppm. Hygroscopic dyeable polyester pellets were dried at 125°C for 18 hours, achieving a moisture content of <30ppm. The reinforced PE as the sheath and the hygroscopic dyeable polyester as the core were conveyed by a screw into a spinning manifold, passed through a pre-filter, and evenly distributed into a sheath-core composite fiber assembly. A C-shaped spinneret was used for sheath-core composite spinning, with the sheath partially enveloping the core. The exposed core portion accounted for 10% of the total sheath-core composite fiber cross-sectional circumference. During the sheath-core composite spinning process, the core portion was maintained at a temperature of 265°C, while the sheath portion was maintained at 235°C. Subsequently, the fiber was subjected to annular cooling, side-blowing, and oiling. Finally, the fiber was wound at 3500 m / min to produce a sheath-core composite fiber with a fineness of 75D and a sheath-core mass ratio of 60:40.

[0081] Example 4

[0082] A sheath-core composite fiber is prepared by the following steps:

[0083] (1) Preparation of hygroscopic dyeable polyester:

[0084] (1.1) Terephthalic acid, ethylene glycol, isophthalic acid, and the catalyst antimony glycolate are mixed by beating at room temperature, and an esterification reaction is carried out at 225-245°C and 0.1-0.3 MPa pressure (initial value is 230°C and 0.16 MPa) for about 2 hours, with the esterification rate controlled at 90%, to obtain an esterified product; the amount of antimony glycolate added is 400 ppm of the theoretical polyester production;

[0085] (1.2) Neopentyl glycol and polyethylene glycol 2000 are added to the esterified product, followed by a preliminary polycondensation reaction at 255-265°C and a pressure of 50-150 Pa (initial value is 260°C and 50 Pa) for 60 minutes; a final polycondensation reaction is carried out at 265-278°C and a pressure of 100-120 Pa (initial value is 265°C and 100 Pa) for 1-2 hours, and the material is pelletized to obtain hygroscopic dyeable polyester pellets; in terephthalic acid, ethylene glycol, isophthalic acid, neopentyl glycol and polyethylene glycol 2000, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.2:1, wherein the amount of terephthalic acid is 400 mol, the amount of isophthalic acid is 5 mol% of terephthalic acid, the amount of neopentyl glycol is 3 mol% of ethylene glycol, and the amount of polyethylene glycol 2000 is 4 wt% of the hygroscopic dyeable polyester.

[0086] (2) Preparation of enhanced PE:

[0087] Graphene masterbatch (purchased from Zhushengfu Nanotechnology, with a filter pressure difference of 1.2 MPa) was added to polyethylene (density 0.96 g / cm 3 , melt index is 20g / 10min), the amount of graphene masterbatch is 6wt% of polyethylene, and the reinforced PE pellets are prepared by a twin-screw granulation process, the twin-screw barrel temperature is 240°C, and the twin-screw main engine speed is 500r / min.

[0088] (3) Skin-core composite spinning:

[0089] Reinforced PE pellets were dried at 80°C for 15 hours, achieving a moisture content of <300ppm. Hygroscopic dyeable polyester pellets were dried at 125°C for 18 hours, achieving a moisture content of <30ppm. The reinforced PE as the sheath and the hygroscopic dyeable polyester as the core were conveyed by a screw into a spinning manifold, passed through a pre-filter, and evenly distributed into a sheath-core composite fiber assembly. A C-shaped spinneret was used for sheath-core composite spinning, with the sheath partially enveloping the core. The exposed core portion accounted for 10% of the total sheath-core composite fiber cross-sectional circumference. During the sheath-core composite spinning process, the core portion was maintained at a box temperature of 265°C, while the sheath portion was maintained at 235°C. Subsequently, the fiber was subjected to annular cooling, side-blowing, and oiling. Finally, the fiber was wound at 3500 m / min to produce a sheath-core composite fiber with a fineness of 75D and a sheath-core mass ratio of 35:65.

[0090] Example 5

[0091] A sheath-core composite fiber is prepared by the following steps:

[0092] (1) Preparation of hygroscopic dyeable polyester:

[0093] (1.1) Terephthalic acid, ethylene glycol, isophthalic acid, and the catalyst antimony glycolate are mixed by beating at room temperature, and an esterification reaction is carried out at 225-245°C and 0.1-0.3 MPa pressure (initial value is 230°C and 0.16 MPa) for about 2 hours, with the esterification rate controlled at 90%, to obtain an esterified product; the amount of antimony glycolate added is 400 ppm of the theoretical polyester production;

[0094] (1.2) Polyethylene glycol 2000 is added to the esterified product, followed by a pre-condensation reaction at 255-265°C and a pressure of 50-150 Pa (initial value is 260°C and 50 Pa) for 60 minutes; a final condensation reaction is carried out at 265-278°C and a pressure of 100-120 Pa (initial value is 265°C and 100 Pa) for 1-2 hours, and when the current reaches the requirement, the material is pelletized and discharged to obtain hygroscopic dyeable polyester pellets; in terephthalic acid, ethylene glycol, isophthalic acid and polyethylene glycol 2000, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.2:1, wherein the amount of terephthalic acid is 400 mol, the amount of isophthalic acid is 5 mol% of terephthalic acid, and the amount of polyethylene glycol 2000 is 6 wt% of the hygroscopic dyeable polyester.

[0095] (2) Preparation of enhanced PE:

[0096] Graphene masterbatch (purchased from Zhushengfu Nanotechnology, with a filter pressure difference of 1.2 MPa) was added to polyethylene (density 0.96 g / cm 3 , melt index is 20g / 10min), the amount of graphene masterbatch is 6wt% of polyethylene, and the reinforced PE pellets are prepared by a twin-screw granulation process, the twin-screw barrel temperature is 240°C, and the twin-screw main engine speed is 500r / min.

[0097] (3) Skin-core composite spinning:

[0098] Reinforced PE pellets were dried at 80°C for 15 hours, achieving a moisture content of <300ppm. Hygroscopic dyeable polyester pellets were dried at 125°C for 18 hours, achieving a moisture content of <30ppm. The reinforced PE as the sheath and the hygroscopic dyeable polyester as the core were conveyed by a screw into a spinning manifold, passed through a pre-filter, and evenly distributed into a sheath-core composite fiber assembly. A C-shaped spinneret was used for sheath-core composite spinning, with the sheath partially enveloping the core. The exposed core portion accounted for 10% of the total sheath-core composite fiber cross-sectional circumference. During the sheath-core composite spinning process, the core portion was maintained at a box temperature of 265°C, while the sheath portion was maintained at 235°C. Subsequently, the fiber was subjected to annular cooling, side-blowing, and oiling. Finally, the fiber was wound at 3500 m / min to produce a sheath-core composite fiber with a fineness of 75D and a sheath-core mass ratio of 35:65.

[0099] Example 6

[0100] A sheath-core composite fiber is prepared by the following steps:

[0101] (1) Preparation of double-terminated hydroxyl block copolyether:

[0102] After ethylene glycol and potassium hydroxide accounting for 35% of the mass of ethylene glycol are uniformly mixed in a reactor, the air in the reactor is replaced with nitrogen twice, and then the mixture is heated to 100°C and vacuumed for dehydration. Nitrogen is then introduced, and ethylene oxide is added in a molar amount of 17.8 times that of ethylene glycol. After reacting for 3 hours at 110-120°C and 0.2-0.3 MPa pressure (initial value is 115°C, 0.2 MPa), 2,3-butylene oxide is added in a molar amount of 1.9 times that of ethylene glycol. The reaction is continued at 110-120°C and 0.2-0.3 MPa pressure (initial value is 115°C, 0.2 MPa) for 2 hours. Phosphoric acid is added for neutralization, and then dehydration is performed to obtain a double-terminated hydroxyl block copolyether with a number average molecular weight of 1053 Da.

[0103] (2) Preparation of hygroscopic dyeable polyester:

[0104] (2.1) Terephthalic acid, ethylene glycol, isophthalic acid, and the catalyst antimony glycolate are mixed by beating at room temperature, and an esterification reaction is carried out at 225-245°C and 0.1-0.3 MPa pressure (initial value is 230°C and 0.16 MPa) for about 2 hours, with the esterification rate controlled at 90%, to obtain an esterified product; the amount of antimony glycolate added is 400 ppm of the theoretical polyester production;

[0105] (2.2) Adding a dihydroxyl-terminated block copolyether to the esterified product, followed by a pre-condensation reaction at 255-265°C and a pressure of 50-150 Pa (initial value is 260°C and 50 Pa) for 60 minutes; and a final condensation reaction at 265-278°C and a pressure of 100-120 Pa (initial value is 265°C and 100 Pa) for 1-2 hours. When the current reaches the requirement, the material is pelletized and discharged to obtain hygroscopic dyeable polyester pellets. In terephthalic acid, ethylene glycol, isophthalic acid and dihydroxyl-terminated block copolyether, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.2:1, wherein the amount of terephthalic acid is 400 mol, the amount of isophthalic acid is 5 mol% of terephthalic acid, and the amount of dihydroxyl-terminated block copolyether is 4wt% of the hygroscopic dyeable polyester.

[0106] (3) Preparation of enhanced PE:

[0107] Same as Example 1.

[0108] (4) Skin-core composite spinning:

[0109] Same as Example 1, except that the hygroscopic dyeable polyester is the hygroscopic dyeable polyester prepared in step (2) of this example.

[0110] Example 7

[0111] A sheath-core composite fiber is prepared by the following steps:

[0112] (1) Preparation of double-terminated hydroxyl block copolyether:

[0113] After ethylene glycol and potassium hydroxide accounting for 35% of the mass of ethylene glycol are uniformly mixed in a reactor, the air in the reactor is replaced with nitrogen twice, and then heated to 100°C and vacuumed for dehydration, nitrogen is then introduced, and ethylene oxide is added in a molar amount 18 times that of ethylene glycol. After reacting at 110-120°C and 0.2-0.3 MPa pressure (initial value is 115°C, 0.2 MPa) for 3.5 hours, 2,3-butylene oxide is added in a molar amount 1.8 times that of ethylene glycol, and the reaction is continued at 110-120°C and 0.2-0.3 MPa pressure (initial value is 115°C, 0.2 MPa) for 2.5 hours. Phosphoric acid is added for neutralization, and then dehydration is performed to obtain a double-terminated hydroxyl block copolyether with a number average molecular weight of 1249 Da.

[0114] (2) Preparation of hygroscopic dyeable polyester:

[0115] Same as Example 6, except that the double-terminal hydroxyl block copolyether is the double-terminal hydroxyl block copolyether prepared in step (1) of this example.

[0116] (3) Preparation of enhanced PE:

[0117] Same as Example 1.

[0118] (4) Skin-core composite spinning:

[0119] Same as Example 1, except that the hygroscopic dyeable polyester is the hygroscopic dyeable polyester prepared in step (2) of this example.

[0120] Example 8

[0121] A sheath-core composite fiber is prepared by the following steps:

[0122] (1) Preparation of double-terminated hydroxyl block copolyether:

[0123] After ethylene glycol and potassium hydroxide accounting for 38% of the mass of ethylene glycol are uniformly mixed in a reactor, the air in the reactor is replaced with nitrogen twice, and then the mixture is heated to 100°C and vacuumed for dehydration. Nitrogen is then introduced, and ethylene oxide is added in a molar amount of 19.0 times that of ethylene glycol. After reacting for 3 hours at 110-120°C and 0.2-0.3 MPa pressure (initial value is 115°C, 0.2 MPa), 2,3-butylene oxide is added in a molar amount of 1.7 times that of ethylene glycol. The reaction is continued at 110-120°C and 0.2-0.3 MPa pressure (initial value is 115°C, 0.2 MPa) for 2 hours. Phosphoric acid is added for neutralization, and then dehydration is performed to obtain a double-terminated hydroxyl block copolyether with a number average molecular weight of 1320 Da.

[0124] (2) Preparation of hygroscopic dyeable polyester:

[0125] Same as Example 6, except that the double-terminal hydroxyl block copolyether is the double-terminal hydroxyl block copolyether prepared in step (1) of this example.

[0126] (3) Preparation of enhanced PE:

[0127] Same as Example 1.

[0128] (4) Skin-core composite spinning:

[0129] Same as Example 1, except that the hygroscopic dyeable polyester is the hygroscopic dyeable polyester prepared in step (2) of this example.

[0130] Comparative Example 1

[0131] This comparative example is based on Example 1, but the polyester used in the core layer is not modified with isophthalic acid and polyethylene glycol 2000. The specific preparation steps of the sheath-core composite fiber of this comparative example are as follows:

[0132] (1) Preparation of polyester:

[0133] (1.1) Terephthalic acid, ethylene glycol, and the catalyst antimony glycolate are mixed by beating at room temperature, and esterification reaction is carried out at 225-245°C and 0.1-0.3 MPa pressure (initial value is 230°C and 0.16 MPa) for about 2 hours, and the esterification rate is controlled to be above 85% to obtain an esterified product; the amount of antimony glycolate added is 400 ppm of the theoretical polyester production;

[0134] (1.2) The esterified product is reacted at 255-265°C and 50-150 Pa pressure (initial value is 260°C and 50 Pa) for 60 minutes for preliminary polycondensation; and is reacted at 265-278°C and 100-120 Pa pressure (initial value is 265°C and 100 Pa) for 1-2 hours for final polycondensation. When the current reaches the requirement, the material is pelletized and discharged to obtain polyester pellets; in terephthalic acid and ethylene glycol, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.2:1, wherein the amount of terephthalic acid used is 400 mol.

[0135] (2) Preparation of enhanced PE:

[0136] Same as Example 1.

[0137] (3) Skin-core composite spinning:

[0138] Same as Example 1, except that the hygroscopic dyeable polyester is the hygroscopic dyeable polyester prepared in step (1) of this comparative example.

[0139] Comparative Example 2

[0140] This comparative example is based on Example 6, but the double-terminated hydroxyl block copolyether is replaced with polyethylene oxide and poly-2,3-butylene oxide, which are added separately. The specific preparation steps of the sheath-core composite fiber of this comparative example are as follows:

[0141] (1) Preparation of polyethylene oxide and poly 2,3-butylene oxide:

[0142] Ethylene glycol and potassium hydroxide (35% by mass based on the mass of ethylene glycol) were uniformly mixed in a reactor, and the air in the reactor was replaced with nitrogen twice. The mixture was then heated to 100°C and vacuumed for dehydration. Nitrogen was then introduced, and ethylene oxide (17.8 times the molar amount of ethylene glycol) was added. The mixture was reacted at 110-120°C and 0.2-0.3 MPa (initial value was 115°C and 0.2 MPa) for 3 hours. Phosphoric acid was then added for neutralization, and the mixture was then dehydrated to produce polyethylene oxide.

[0143] After ethylene glycol and potassium hydroxide accounting for 35% of the mass of ethylene glycol are uniformly mixed in a reactor, the air in the reactor is replaced with nitrogen twice, and then heated to 100°C and vacuumed for dehydration. Nitrogen is then introduced, and 2,3-butylene oxide is added in a molar amount that is 1.9 times that of ethylene glycol. The reaction is continued at 110-120°C and 0.2-0.3Mpa pressure (initial value is 115°C and 0.2Mpa) for 2 hours. Phosphoric acid is added for neutralization, and then dehydration is carried out to obtain poly 2,3-butylene oxide.

[0144] (2) Preparation of hygroscopic dyeable polyester:

[0145] (2.1) Terephthalic acid, ethylene glycol, isophthalic acid, and the catalyst antimony glycol are mixed by beating at room temperature, and an esterification reaction is carried out at 225-245°C and 0.1-0.3 MPa pressure (initial value is 230°C and 0.16 MPa) for about 2 hours, with the esterification rate being controlled to be above 85%, to obtain an esterified product; the amount of antimony glycol added is 400 ppm of the theoretical polyester production;

[0146] (2.2) Polyethylene oxide and poly-2,3-butylene oxide are added to the esterified product, followed by a pre-polycondensation reaction at 255-265°C and a pressure of 50-150 Pa (initial value is 260°C and 50 Pa) for 40-60 min; a final polycondensation reaction is carried out at 265-278°C and a pressure of 100-120 Pa (initial value is 265°C and 100 Pa) for 1-2 h, and when the current reaches the requirement, the material is pelletized and discharged to obtain hygroscopic dyeable polyester pellets; in terephthalic acid, ethylene glycol, isophthalic acid, polyethylene oxide and poly-2,3-butylene oxide, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.2:1, wherein the amount of terephthalic acid is 400 mol, the amount of isophthalic acid is 5 mol% of terephthalic acid, and the amounts of polyethylene oxide and poly-2,3-butylene oxide are both 2 wt% of the hygroscopic dyeable polyester.

[0147] (3) Preparation of enhanced PE:

[0148] Same as Example 1.

[0149] (4) Skin-core composite spinning:

[0150] Same as Example 1, except that the hygroscopic dyeable polyester is the hygroscopic dyeable polyester prepared in step (2) of this comparative example.

[0151] Comparative Example 2

[0152] This comparative example is based on Example 6, except that the double-terminated hydroxyl block copolyether is replaced with polyethylene oxide. The specific preparation steps of the core-skin composite fiber of this comparative example are as follows:

[0153] (1) Preparation of polyethylene oxide and

[0154] Ethylene glycol and potassium hydroxide (35% by mass based on the mass of ethylene glycol) were uniformly mixed in a reactor, and the air in the reactor was replaced with nitrogen twice. The mixture was then heated to 100°C and vacuumed for dehydration. Nitrogen was then introduced, and ethylene oxide (17.8 times the molar amount of ethylene glycol) was added. The mixture was reacted at 110-120°C and 0.2-0.3 MPa (initial value was 115°C and 0.2 MPa) for 3 hours. Phosphoric acid was then added for neutralization, and the mixture was then dehydrated to produce polyethylene oxide.

[0155] (2) Preparation of hygroscopic dyeable polyester:

[0156] (2.1) Terephthalic acid, ethylene glycol, isophthalic acid, and the catalyst antimony glycol are mixed by beating at room temperature, and an esterification reaction is carried out at 225-245°C and 0.1-0.3 MPa pressure (initial value is 230°C and 0.16 MPa) for about 2 hours, with the esterification rate being controlled to be above 85%, to obtain an esterified product; the amount of antimony glycol added is 400 ppm of the theoretical polyester production;

[0157] (2.2) Add polyethylene oxide to the ester, then react at 255-265℃ and 50-150Pa pressure (initial value is 260℃, 50Pa) for 40-60min for pre-condensation; react at 265-278℃ and 100-120Pa pressure (initial value is 265℃, 100Pa) for 1-2h for final condensation, and when the current reaches the requirement, cut the material into pellets to obtain hygroscopic dyeable polyester pellets; in terephthalic acid, ethylene glycol, isophthalic acid and polyethylene oxide, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.2:1, wherein the amount of terephthalic acid is 400mol, the amount of isophthalic acid is 5mol% of terephthalic acid, the amount of polyethylene oxide is 4wt% of the hygroscopic dyeable polyester, and the amount of ethylene glycol is.

[0158] (3) Preparation of enhanced PE:

[0159] Same as Example 1.

[0160] (4) Skin-core composite spinning:

[0161] Same as Example 1, except that the hygroscopic dyeable polyester is the hygroscopic dyeable polyester prepared in step (2) of this comparative example.

[0162] Comparative Example 4

[0163] This comparative example is based on Example 6, but the double-terminated hydroxyl block copolyether is replaced with polyethylene oxide and poly-2,3-butylene oxide, which are added separately. The specific preparation steps of the sheath-core composite fiber of this comparative example are as follows:

[0164] (1) Preparation of poly 2,3-butylene oxide:

[0165] After ethylene glycol and potassium hydroxide accounting for 35% of the mass of ethylene glycol are uniformly mixed in a reactor, the air in the reactor is replaced with nitrogen twice, and then heated to 100°C and vacuumed for dehydration. Nitrogen is then introduced, and 2,3-butylene oxide is added in a molar amount that is 1.9 times that of ethylene glycol. The reaction is continued at 110-120°C and 0.2-0.3Mpa pressure (initial value is 115°C and 0.2Mpa) for 2 hours. Phosphoric acid is added for neutralization, and then dehydration is carried out to obtain poly 2,3-butylene oxide.

[0166] (2) Preparation of hygroscopic dyeable polyester:

[0167] (2.1) Terephthalic acid, ethylene glycol, isophthalic acid, and the catalyst antimony glycol are mixed by beating at room temperature, and an esterification reaction is carried out at 225-245°C and 0.1-0.3 MPa pressure (initial value is 230°C and 0.16 MPa) for about 2 hours, with the esterification rate being controlled to be above 85%, to obtain an esterified product; the amount of antimony glycol added is 400 ppm of the theoretical polyester production;

[0168] (2.2) Add poly 2,3-butylene oxide to the ester, and then react at 255-265 ° C and 50-150 Pa pressure (initial value is 260 ° C and 50 Pa) for 40-60 minutes for pre-condensation; react at 265-278 ° C and 100-120 Pa pressure (initial value is 265 ° C and 100 Pa) for 1-2 hours for final polycondensation, and when the current reaches the requirement, cut the material into pellets to obtain hygroscopic dyeable polyester pellets; in terephthalic acid, ethylene glycol, isophthalic acid and poly 2,3-butylene oxide, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.2:1, wherein the amount of terephthalic acid is 400 mol, the amount of isophthalic acid is 5 mol% of terephthalic acid, the amount of poly 2,3-butylene oxide is 4wt% of the hygroscopic dyeable polyester, and the amount of ethylene glycol is.

[0169] (3) Preparation of enhanced PE:

[0170] Same as Example 1.

[0171] (4) Skin-core composite spinning:

[0172] Same as Example 1, except that the hygroscopic dyeable polyester is the hygroscopic dyeable polyester prepared in step (2) of this comparative example.

[0173] Comparative Example 5

[0174] This comparative example is based on Example 6, in which the relative content of polyethylene oxide in the double-terminated hydroxyl block copolyether is increased and the relative content of poly-2,3-butylene oxide is reduced. The specific preparation steps of the core-skin composite fiber of this comparative example are as follows:

[0175] (1) Preparation of double-terminated hydroxyl block copolyether:

[0176] After ethylene glycol and potassium hydroxide accounting for 35% of the mass of ethylene glycol are uniformly mixed in a reactor, the air in the reactor is replaced with nitrogen twice, and then heated to 100°C and vacuumed for dehydration, nitrogen is then introduced, and ethylene oxide is added in a molar amount of 19.2 times that of ethylene glycol. After reacting at 110-120°C and 0.2-0.3 MPa pressure (initial value is 115°C, 0.2 MPa) for 3.5 hours, 2,3-butylene oxide is added in a molar amount of 0.5 times that of ethylene glycol, and the reaction is continued at 110-120°C and 0.2-0.3 MPa pressure (initial value is 115°C, 0.2 MPa) for 1.5 hours. Phosphoric acid is added for neutralization, and then dehydration is performed to obtain a double-terminated hydroxyl block copolyether with a number average molecular weight of 1096 Da.

[0177] (2) Preparation of hygroscopic dyeable polyester:

[0178] Same as Example 6, except that the double-terminal hydroxyl block copolyether is the double-terminal hydroxyl block copolyether prepared in step (1) of this comparative example.

[0179] (3) Preparation of enhanced PE:

[0180] Same as Example 1.

[0181] (4) Skin-core composite spinning:

[0182] Same as Example 1, except that the hygroscopic dyeable polyester is the hygroscopic dyeable polyester prepared in step (2) of this comparative example.

[0183] Comparative Example 6

[0184] This comparative example is based on Example 6, but reduces the relative content of polyethylene oxide in the double-terminated hydroxyl block copolyether and increases the relative content of poly-2,3-butylene oxide. The specific preparation steps of the core-skin composite fiber of this comparative example are as follows:

[0185] (1) Preparation of double-terminated hydroxyl block copolyether:

[0186] After ethylene glycol and potassium hydroxide accounting for 35% of the mass of ethylene glycol are uniformly mixed in a reactor, the air in the reactor is replaced with nitrogen twice, and then the reaction mixture is heated to 100°C and vacuumed for dehydration. Nitrogen is then introduced, and ethylene oxide is added in a molar amount of 12.8 times that of ethylene glycol. After reacting for 160 minutes at 110-120°C and 0.2-0.3 MPa pressure (initial value is 115°C, 0.2 MPa), 2,3-butylene oxide is added in a molar amount of 6.9 times that of ethylene glycol. The reaction is continued at 110-120°C and 0.2-0.3 MPa pressure (initial value is 115°C, 0.2 MPa) for 3 hours. Phosphoric acid is added for neutralization, and then dehydration is performed to obtain a double-terminated hydroxyl block copolyether with a number average molecular weight of 1109 Da.

[0187] (2) Preparation of hygroscopic dyeable polyester:

[0188] Same as Example 6, except that the double-terminal hydroxyl block copolyether is the double-terminal hydroxyl block copolyether prepared in step (1) of this comparative example.

[0189] (3) Preparation of enhanced PE:

[0190] Same as Example 1.

[0191] (4) Skin-core composite spinning:

[0192] Same as Example 1, except that the hygroscopic dyeable polyester is the hygroscopic dyeable polyester prepared in step (2) of this comparative example.

[0193] Test Example 1: The role of skin-core composite structure and modified monomer

[0194] The sheath-core composite fiber fabrics prepared in Examples 1-8 and Comparative Example 1 were dyed and evaluated. Example 2 used cationic dyes, and Examples 1, 3-8, and Comparative Example 1 used disperse dyes. The dyeing treatment was carried out at 96°C (dyeing at 30°C, rising to 65°C at 2°C / min, rising to 80°C at 1°C / min, rising to 96°C at 1°C / min, and maintaining the constant temperature for 40min). The dye uptake is shown in Table 1.

[0195] The dyed fabric samples were tested for coolness. The test standard was GB / T 35263-2017. The coolness coefficient is shown in Table 1.

[0196] Table 1

[0197] Dyeing rate (%) <![CDATA[Cooling coefficient (J / (cm 2 ·s))]]> Example 1 92 0.20 Example 2 93 0.21 Example 3 89 0.25 Example 4 95 0.22 Example 5 98 0.23 Example 6 97 0.22 Example 7 97 0.20 Example 8 96 0.21 Comparative Example 1 77 0.19

[0198] From the table above we can see that:

[0199] (1) The dye uptake of Examples 1-8 is significantly higher than that of Comparative Example 1, indicating that the dyeability of the core-skin composite fiber can be improved by adding isophthalic acid or sodium 5-sulfonate isophthalic acid, polyethylene glycol 2000 double-terminal hydroxyl block copolyether and neopentyl glycol during the preparation of the core layer polyester.

[0200] (2) The dye uptake of Example 1 is higher than that of Example 3, while the coolness coefficient is lower than that of Example 3, indicating that increasing the proportion of the polyethylene-based sheath layer in the sheath-core composite fiber can improve the contact coolness of the fiber, while increasing the proportion of the hygroscopic and dyeable polyester-based core layer can improve the dyeability of the fiber.

[0201] (3) The dye uptake and coolness coefficient of Examples 4 and 5 are higher than those of Example 1, indicating that in the process of preparing the core layer polyester, the dyeability and contact coolness of the core-skin composite fiber can be improved by adding neopentyl glycol or increasing the amount of polyethylene glycol 2000.

[0202] Test Example 2: Effect of double-terminated hydroxyl block copolyether

[0203] The sheath-core composite fibers prepared in Examples 6-8 and Comparative Examples 2-6 were tested for breaking strength and evaluated for disperse dye dyeing according to the method in Test Example 1. The measured breaking strength and dye uptake are shown in Table 2.

[0204] Table 2

[0205] Dyeing rate (%) Breaking strength (cN / dtex) Example 6 97 4.4 Example 7 97 4.7 Example 8 96 4.6 Comparative Example 2 93 4.5 Comparative Example 3 91 3.6 Comparative Example 4 87 4.5 Comparative Example 5 94 3.8 Comparative Example 6 90 4.5

[0206] From the table above we can see that:

[0207] (1) The dye uptake of Example 6 is significantly higher than that of Comparative Examples 2-4, indicating that the use of a double-terminal hydroxyl block copolyether composed of polyethylene oxide segments and poly(2,3-butylene oxide) segments as a modifying monomer in the hygroscopic dyeable polyester can improve the dye uptake of the core-sheath composite fiber to a greater extent than that of polyethylene oxide or poly(2,3-butylene oxide) or a mixture of the two.

[0208] (2) The breaking strength of Example 6 is significantly higher than that of Comparative Example 5, and the dyeing rate is significantly higher than that of Comparative Example 6, indicating that in the double-terminal hydroxyl block copolyether, when the relative content of the polyethylene oxide segment is high and the relative content of poly-2,3-butylene oxide is low, the strength of the core-sheath composite fiber will be reduced, and vice versa, the dyeability of the core-sheath composite fiber will be reduced.

[0209] Unless otherwise specified, the raw materials and equipment used in the present invention are commonly used in the art; the methods used in the present invention are conventional methods in the art unless otherwise specified.

[0210] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still fall within the scope of protection of the technical solution of the present invention.

Claims

1. A core-sheath composite fiber having a cool touch and high dyeability, characterized in that: It includes a skin layer and a core layer; the skin layer is a polyethylene-based skin layer; the material of the core layer is a hygroscopic and dyeable polyester copolymerized by terephthalic acid, ethylene glycol and a modified monomer, the modified monomer includes a double-terminal hydroxyl block copolyether composed of a polyethylene oxide segment and a poly-2,3-butylene oxide segment, and the double-terminal hydroxyl block copolyether is polymerized by ethylene glycol, ethylene oxide and 2,3-butylene oxide in a molar ratio of 1:17.8-19.0:1.7-1.

9.

2. The core-sheath composite fiber according to claim 1, wherein: The modified monomer further comprises one or more of a dibasic acid monomer, a diol monomer and an alkyd monomer; the dibasic acid monomer comprises isophthalic acid and / or isophthalic acid sulfonate; the diol monomer comprises one or more of neopentyl glycol, 1,3-butanediol and polytetramethylene glycol; the alkyd monomer comprises polyglycolic acid.

3. The core-sheath composite fiber according to claim 2, characterized in that: The preparation method of the hygroscopic dyeable polyester comprises the following steps: (1.1) Esterifying terephthalic acid, ethylene glycol, and a dibasic acid monomer to obtain an esterified product; (1.2) The esterified product is mixed with a diol monomer and / or an alkyd monomer, and subjected to preliminary polycondensation and final polycondensation to obtain a hygroscopic dyeable polyester.

4. The core-sheath composite fiber according to claim 2 or 3, characterized in that: In the terephthalic acid, ethylene glycol and modified monomer, the ratio of the total molar amount of hydroxyl groups to the total molar amount of carboxyl groups is 1.15-1.4:

1.

5. The core-sheath composite fiber according to claim 1, wherein: The material of the skin layer is a mixture of graphene masterbatch and polyethylene, and the amount of graphene masterbatch is 5-6wt% of the polyethylene.

6. The core-sheath composite fiber according to claim 1, wherein: The skin layer forms a structure that partially encapsulates the core layer outside the core layer, and the arc length of the exposed part of the core layer accounts for 5-20% of the circumference of the entire cross-section of the skin-core composite fiber.

7. The core-sheath composite fiber according to claim 1, wherein: The mass ratio of the skin layer to the core layer is 35-70:65-30.

8. The core-sheath composite fiber according to claim 1, wherein: The preparation method of the dihydroxy-terminated block copolyether comprises the following steps: mixing ethylene glycol and potassium hydroxide at a mass ratio of 1:0.35-0.38, adding ethylene oxide in a molar amount 17.8-19.0 times that of ethylene glycol under the protection of inert gas, reacting at 110-120° C. and 0.2-0.3 MPa for 3-3.5 hours, then adding 2,3-butylene oxide in a molar amount 1.7-1.9 times that of ethylene glycol, and continuing to react at 110-120° C. and 0.2-0.3 MPa for 2-2.5 hours to obtain the dihydroxy-terminated block copolyether.

9. A method for preparing a core-sheath composite fiber according to any one of claims 1 to 8, characterized in that: The following steps are involved: The sheath material and the core material are continuously crystallized and dried to prepare sheath dry material and core dry material, and then sheath-core composite spinning is performed to obtain sheath-core composite fiber.