Polyamide sea-island fiber, method for producing the same, and use thereof

Abstract

The present invention relates to the technical field of polyamide materials, specifically to a polyamide islands-in-sea fiber, its manufacturing method, and its use. In the polyamide islands-in-sea fiber, the island component is a polyamide resin selected from one of polyamide 56, polyamide 510, polyamide 511, polyamide 512, polyamide 513, polyamide 514, polyamide 515, and polyamide 516, preferably polyamide 56 or polyamide 510, and the sea component is one of polyethylene, low-density polyethylene, polystyrene, water-soluble polyester, polyester, and polyurethane, preferably polyethylene, low-density polyethylene, or water-soluble polyester. The polyamide islands-in-sea fiber of the present invention has better mechanical properties, better flexibility, good dyeing properties, high-grade dye gray scale, high dye uptake, high dye depth, and high color fastness.

Description

Technical Field

[0001] The present invention belongs to the technical field of polyamide materials and relates to polyamide sea-island fibers, a method for manufacturing the same, and uses thereof.

Background Art

[0002] Sea-island type composite fibers, also known as hyper-conjugate fibers, are formed by embedding polymers in an extremely fine form (fibrils) in another polymer (matrix). They are also called sea-island fibers because the dispersed phase (fibrils) is in the form of islands in the fiber cross-section. Ultra-fine fibers are obtained by dissolving the sea component from the sea-island fibers. Sea-island fibers can be classified into two types according to the distribution rule, namely, Fixed island type sea-island fibers and non- Fixed island type sea-island fibers. Fixed Island type sea-island fibers are uniform and immobile with respect to the island distribution and are generally spun by a composite spinning method. That is, two polymers are spun through a melt composite spinning machine and a special spinning pack, where one component is uniformly distributed as islands in another polymer (sea component). Non- Fixed The islands of island fibers are Not fixed not sufficiently uniform either. The fineness of non- Fixed island type fibers varies greatly. The thinnest non- Fixed island type fibers are Fixed thinner than island type fibers, but thicker non- Fixed island type fibers can have a fineness of 0.1 dtex or more. Non- Fixed island type fibers are mainly manufactured by blending. The sea component in the sea-island type composite fiber is a water-soluble polymer. The sea component is dissolved and removed with water by hydrolysis to obtain isolated island components. In this way, ultra-fine fibers with a linear density of 0.03 to 0.3 dtex are formed, which are mainly used for suede-like materials. Also, when the island component dissolves, it becomes a hollow fiber, which is mainly used as an adsorbent.

[0003] The ultra-fine characteristics of sea-island fibers bring about excellent properties that cannot be obtained with conventional fibers: 1. a soft and delicate touch, a significant reduction in bending rigidity; 2. an improvement in good softness and bending rigidity; 3. a soft luster and an increase in diffused light; 4. high detergency, an increase in the contact area; 5. high water absorbency and high oil absorbency; 6. a high-density structure; 7. strong heat insulation, and more air is retained.

[0004] The product combines the characteristics of natural leather (such as moisture absorbency, softness, comfort, etc.) and advantages such as good chemical resistance, good physical properties, water resistance, and light weight. It is mainly used in fields such as clothing, household textiles, and industrial applications. Clothing includes artificial wool, imitation silk, artificial leather, imitation peach skin, imitation suede, high-density waterproof fabrics, heat insulation materials, safety boots, etc. Household textile fields include high-performance cleaning clothing, sofa covers, curtain fabrics, cases, etc. Industrial application fields include electronic product protectors, automotive equipment, high-performance adsorption and filtration materials, high oil absorbency materials, and high water absorbency materials.

[0005] Sea-island composite fibers have a low linear density, a large specific surface area, can quickly absorb more dyes, and have a smaller fiber radius. Therefore, the distance for dyes to diffuse in such fibers is short, the diffusion time is short, and the dyes are likely to penetrate deeply. Furthermore, the fibers have a high content of amorphous regions and fast dyeing dyes, so the levelness of sea-island fibers deteriorates. Ultra-fine fibers have a large surface area, the surface is not sufficiently smooth, a large amount of dyes are used, and a large amount of the dye present is difficult to remove by washing. Therefore, the wet fastness of dyes on ultra-fine fiber fabrics is lower than that on conventional fibers.

[0006] CN106987923A discloses that a preservation solution dyes black sea-island fibers. The black sea-island fibers dyed with the preservation solution are used to solve the problems that the sea-island fibers are difficult to be deeply dyed and have poor color fastness. The fibers include a sea component and an island component. The island component contains 1-60% by weight of a black masterbatch and 10-90% by weight of polyamide 6 or polyester; the sea component is an alkali-soluble polyester; after splitting, the fineness is less than 0.08 dtex, the blackness L value is less than 15, and the color fastness is 4 grades or more. The sea-island fibers are black, and due to the single color, their applications are limited.

[0007] CN106435821A discloses blended or melt sea-island fibers, ultrafine fibers, and a preparation method thereof. The island component is polyamide, and the sea component is a water-soluble polyester compound. The method includes mixing, melting, and spinning polyamide and water-soluble polyester, putting the sea-island fibers into warm water, performing a weight reduction treatment with water to remove the sea component polyester, and obtaining polyamide ultrafine fibers. In the examples, the island component is selected from polyamide 6 and polyamide 66, and the sea component is selected from water-soluble polyesters. The sea-island fibers are prepared by a mixed spinning method, where the island component is used as the dispersed phase and the sea component is used as the matrix. The mixing during the process is non-uniform, which results in a non-uniform distribution of the island component. The thicknesses of the components are greatly different during splitting, which affects subsequent dyeing and causes color differences.

Summary of the Invention

Problems to be Solved by the Invention

[0008] The first object of the present invention is to provide polyamide sea-island fibers having better mechanical properties, better flexibility, and good dyeing properties simultaneously.

[0009] The second object of the present invention is to provide a method for manufacturing polyamide sea-island fibers, wherein the polyamide sea-island fibers use materials from a non-petroleum-based source (i.e., a bio-based source) that does not cause serious pollution and is beneficial to environmental protection.

[0010] The third object of the present invention is to provide the use of polyamide sea-island fibers.

Means for Solving the Problems

[0011] To achieve the above object, the present invention provides the following solutions.

[0012] [Polyamide Sea-Island Fibers] The present invention provides polyamide sea-island fibers, wherein the island component is a polyamide resin selected from one of polyamide 56, polyamide 510, polyamide 511, polyamide 512, polyamide 513, polyamide 514, polyamide 515 and polyamide 516, preferably polyamide 56 or polyamide 510, and the sea component is one of polyethylene, low-density polyethylene, polystyrene, water-soluble polyester, polyester and polyurethane, preferably polyethylene, low-density polyethylene or water-soluble polyester.

[0013] The island component can be a super bright (SB) polyamide resin, a semi-dull (SD) polyamide resin, a full dull (FD) polyamide resin and mixtures thereof.

[0014] In some preferred embodiments of the present invention, the island component polyamide resin has a relative viscosity of 2.4 to 3.0, preferably 2.5 to 2.9, more preferably 2.6 to 2.8; and / or the mass ratio of the island component to the sea component of the sea-island fiber is 20 to 80:80 to 20, more preferably 30 to 70:70 to 30.

[0015] In some preferred embodiments of the present invention, as the sea-island fiber, Fixed island-type sea-island fibers and non- FixedExamples include island-in-sea fibers; and / or Fixed The number of islands in the island-in-sea fiber is from 16 to 500;

[0016] In some preferred embodiments of the present invention, the polyamide island-in-sea fiber has a fineness of 10 to 300 dtex, preferably 20 to 200 dtex, more preferably 30 to 100 dtex, and / or the polyamide island-in-sea fiber has a breaking strength of 2.0 to 5.0 cN / dtex, preferably 2.5 to 4.5 cN / dtex, more preferably 3.0 to 4.0 cN / dtex, and / or the polyamide island-in-sea fiber has an elongation at break of 30 to 80%, preferably 40 to 70%, more preferably 45 to 60%, and / or the polyamide island-in-sea fiber has an initial modulus of 20 to 50 cN / dtex, preferably 23 to 45 cN / dtex, more preferably 28 to 38 cN / dtex, and / or after the polyamide island-in-sea fiber is split, the polyamide island-in-sea fiber has a monofilament fineness of 0.001 to 0.2 dtex, preferably 0.005 - 0.1 dtex, more preferably 0.01 - 0.05 dtex, and / or the polyamide island-in-sea fiber has a K / S value of 15 or more, preferably 20 or more, more preferably 25 or more; and / or the polyamide island-in-sea fiber has a dye uptake of 90% or more, preferably 93% or more, more preferably 96% or more; and / or the polyamide island-in-sea fiber has a dyeing uniformity (gray scale) of grade 3.5 or more, preferably 4.0 or more, more preferably 4.5 or more; and / or the polyamide island-in-sea fiber has a fastness to fading of grade 3.0 or more, preferably grade 3.5 or more, more preferably grade 4.0 or more, even more preferably grade 4.5 or more; and / or the polyamide island-in-sea fiber has a fastness to dyeing of grade 3.0 or more, preferably grade 3.5 or more, more preferably 4.0, even more preferably 4.5 or more. Soap fastness; and / or the polyamide island-in-sea fiber has a fastness to dyeing of grade 3.0 or more, preferably grade 3.5 or more, more preferably 4.0, even more preferably 4.5 or more. Soap fastness.

[0017] The present invention provides Fixed a method for producing the above-mentioned island-in-sea fiber, the method comprising the following steps: 1) Heat and melt the island component resin and the sea component resin respectively to obtain two melts. Transport the two melts through a pipe to a spinning beam. Accurately measure each melt with a metering pump and inject it into a sea-island composite material spinning pack in the spinning beam. Distribute the two melts through a distribution pipe in the spinning pack, converge and extrude them at the inlet of the spinneret orifice. Here, the water content of the island component is less than 1500 ppm, and the water content of the sea component is less than 300 ppm.

[0018] 2) Cool, spin finish, stretch, heat set, and wind up the as-formed fibers extruded in step 1) to Fixed obtain sea-island fibers.

[0019] The heating in step 1) is carried out in a screw extruder, and the screw extruder preferably includes five zones for heating; For the screw of the island component, the temperature of the first zone is 200 - 260 °C, the temperature of the second zone is 230 - 280 °C, the temperature of the third zone is 240 - 290 °C, the temperature of the fourth zone is 260 - 300 °C, the temperature of the fifth zone is 270 - 310 °C, and / or For the screw for sea components, the temperature of the first zone is 120 - 220 °C, the temperature of the second zone is 140 - 240 °C, the temperature of the third zone is 160 - 260 °C, the temperature of the fourth zone is 180 - 280 °C, and the temperature of the fifth zone is 160 - 290 °C. For sea-island fibers, reasonable adjustment of the temperatures of the two melts is the key to controlling the cross-sectional shapes of the two components after they are conjugated. If the temperature is too high or too low, the cross-sectional shape of the as-formed yarn changes, and the uniformity of the cross-sectional shape also decreases. Generally, the difference in the melt viscosities of the two polymers affects the cross-sectional shape. If the viscosities of the two melts are very different, it affects the uniformity of the cross-sectional shape, and the island component may even adhere or form a "solid" body. This makes it impossible to separate the island component during the post-treatment of splitting. Therefore, an appropriate spinning temperature should be selected during spinning. This method is adjusted so that the spinning temperature falls within the above temperature range and the melt viscosities of the sea component and the island component match each other.

[0020] In step 1), the temperature of the spinning beam is 200 - 300 °C; the spinning pack pressure of the island component is 10.0 - 15.0 MPa; the spinning pack pressure of the sea component is 8.0 - 15.0 MPa; the difference in the spinning pack pressures between the sea component and the island component is controlled to be 4.0 MPa or less.

[0021] In step 2), cooling is carried out by quench air or cross air blow, the air speed is 0.2 - 1.2 m / s, preferably 0.2 - 1.0 m / s, more preferably 0.3 - 0.8 m / s, the air temperature of the quench air is 15 - 30 °C, preferably 20 - 27 °C, more preferably 22 - 25 °C, and / or the oil pickup is 0.2 - 1.0 wt%, preferably 0.3 - 0.8 wt%, more preferably 0.4 - 0.6 wt%, the oil pickup is calculated based on the weight of the fiber, and / or the drawing process is that the as-formed yarn after spinning finish is directed through a supply roller for drawing towards a hot drawing roller, the draw ratio is preferably 2.0 - 5.0, more preferably 2.5 - 3.0; and / or Heat setThe temperature is 150 - 220°C, preferably 160 - 200°C, more preferably 170 - 180°C; and / or the winding speed is 1000 - 6000 m / min, preferably 2000 - 5000 m / min, more preferably 2500 - 4000 m / min.

[0022] In some preferred embodiments of the present invention, the method further includes splitting the sea-island fiber obtained in step 2) in a solvent to remove the sea component; The solvent is 1 - 10 wt% aqueous solution of toluene, xylene and sodium hydroxide; the splitting temperature is 60 - 100°C, preferably 65 - 95°C, more preferably 75 - 85°C; the splitting time is 10 - 70 minutes, preferably 20 - 60 minutes, more preferably 30 - 50 minutes; the bath ratio is 1:10 - 1:80, preferably 1:20 - 1:60, more preferably 1:30 - 1:40; and / or the weight loss rate of the sea-island fiber is 20 - 50 wt%, preferably 25 - 45 wt%, more preferably 30 - 40 wt%.

[0023] The present invention is the non- Fixed A method for manufacturing the above non-island type sea-island fiber, comprising the following steps: a) Uniformly mixing the island component and the sea component at a certain ratio, then heating and melting the mixture; conveying the obtained blended melt through a pipe to a spinning beam; precisely metering the blended melt by a metering pump and injecting it into a single-component spinning pack in the spinning beam; extruding the blended melt through a spinneret orifice; here, the island component has a moisture content of less than 1500 ppm; the sea component has a moisture content of less than 300 ppm;

[0024] 2) Cooling, spinning finishing, stretching, heat setting and winding the extruded as-formed fiber to obtain a non- Fixed island type sea-island fiber.

[0025] In step a), the heating is carried out in a screw extruder, where the screw extruder preferably includes five zones for heating; the temperature of the first zone is 180 - 240 °C; the temperature of the second zone is 200 - 260 °C; the temperature of the third zone is 220 - 270 °C; the temperature of the fourth zone is 240 - 280 °C; and the temperature of the fifth zone is 200 - 300 °C.

[0026] In step a), the temperature of the spinning beam is 200 - 300 °C, and the spinning pack pressure is 10.0 - 25.0 MPa.

[0027] In step b), the cooling is carried out by quench air or cross air blow, the air speed is 0.2 - 1.2 m / s, preferably 0.4 - 1.0 m / s, more preferably 0.6 - 0.8 m / s, the air temperature of the quench air is 15 - 30 °C, preferably 23 - 27 °C, more preferably 24 - 25 °C, and / or the oil pickup is 0.2 - 1.0 wt%, preferably 0.3 - 0.8 wt%, more preferably 0.4 - 0.6 wt%, and / or the stretching process is that the as-spun formed yarn is directed through a supply roller for stretching towards a hot stretching roller, the draw ratio is preferably 2.0 - 5.0, more preferably 2.5 - 3.0; and / or Heat set the temperature is 150 - 220 °C, preferably 160 - 200 °C, more preferably 170 - 180 °C; and / or the winding speed is 1000 - 6000 m / min, preferably 2000 - 5000 m / min, more preferably 2500 - 4000 m / min.

[0028] In some preferred embodiments of the present invention, the method further includes splitting the sea-island fiber obtained in step b) in a solvent to remove the sea component; The solvent is toluene, xylene, and an aqueous solution of 1 to 10 wt% sodium hydroxide; the splitting temperature is 60 to 100 °C, preferably 65 to 95 °C, more preferably 75 to 85 °C; the splitting time is 10 to 70 minutes, preferably 20 to 60 minutes, more preferably 30 to 50 minutes; the liquor ratio is 1:10 to 1:80, preferably 1:20 to 1:60, more preferably 1:30 to 1:40; and / or the weight loss rate of the sea-island fiber is 20 to 50 wt%, preferably 25 to 45 wt%, more preferably 30 to 40 wt%.

[0029] [Use of polyamide sea-island fiber] Examples of polyamide sea-island fibers include filaments and staple fibers, which are mainly used in the manufacturing fields of artificial fur, imitation silk, artificial leather, imitation peach skin, imitation suede, high-density waterproof fabrics, high-performance washing clothes, high-performance adsorption / filtration materials, high oil-absorbing materials, high water-absorbing materials, heat insulation materials, medical materials, automobile equipment materials, safety shoes, cases, handbags, sofas, etc. [Advantages of the invention]

[0030] The fabric made of the polyamide sea-island fiber of the present invention is softer to the touch, has better penetration resistance, and better dyeability compared to conventional sea-island fabrics. Such a fabric is more suitable for wiping cloths. It produces good effects and is less likely to damage the surface of the object being wiped. The excellent complete dull effect of such a fabric is fully reflected in the fabrics for down jackets and nurses' uniforms. Furthermore, when such fibers are split, they can produce ultrafine fibers with a smaller fineness, a softer touch, and less penetration resistance compared to the ultrafine filaments of conventional sea-islands. This manufacturing method is simple and easy to operate.

[0031] By adopting the above technical solutions, the present invention has the following advantages compared to the prior art:

[0032] First, since the raw material of the island component of the polyamide sea-island fiber according to the present invention is prepared by a biological process, it is a green material that does not depend on petroleum resources and does not cause serious environmental pollution. In addition, it can reduce carbon dioxide emissions and the greenhouse effect.

[0033] Second, the polyamide sea-island fiber of the present invention has better mechanical properties and better softness.

[0034] Third, the polyamide sea-island fiber of the present invention has good dyeability, a high-grade dyeing gray scale, high dye uptake, high dyeing depth, and high color fastness.

[0035] Finally, the polyamide sea-island fiber of the present invention has a monofilament fineness of 0.01 to 0.2 dtex after splitting. The monofilament is fine, and the fiber has a soft and delicate touch. The bending rigidity is significantly reduced, and the luster is soft. The fiber has a large specific surface area and a high-density structure. It is more suitable for use in fields such as artificial fur, imitation silk, artificial leather, artificial peach skin, artificial suede, high-density waterproof cloth, high-performance washing clothing, high-performance adsorption / filtration materials, high oil-absorbing materials, high water-absorbing materials, heat insulation materials, medical materials, automotive equipment materials, safety shoes, protective gear for electronic products, cases, handbags, sofas, etc.

Embodiments for Carrying Out the Invention

[0036] To make the objectives, technical solutions, and advantages of the present disclosure clearer, the technical solutions of the present disclosure will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments in the present disclosure without creative work shall fall within the protection scope of the present disclosure.

[0037] (1) Fineness: The fineness is measured according to GB / T 14343. (2) Tensile strength: The tensile strength is measured according to GB / T 14344-2008. (3) Elongation at break: The elongation at break is measured in accordance with GB / T 14344-2008.

[0038] (4) Initial modulus: The initial modulus is measured in accordance with GB / T 14344. The initial modulus is defined as the breaking strength corresponding to 1% of the elongation at break.

[0039] (5) Weight loss Weight loss (weight %) = (fiber weight before splitting - fiber weight after splitting) / fiber weight before splitting × 100%;

[0040] (6) Dyeing uniformity (gray scale) / grade: The dyeing uniformity is measured in accordance with the FZ / T 50008 test method for the dyeing uniformity of polyamide filaments.

[0041] (7) K / S value: The K / S value of the dyed fabric is measured with a computer color measurement and color matching device. The K / S value represents the apparent color depth value.

Number

[0042] (8) Dye uptake: The concentration difference of the dye liquor before and after dyeing is measured using a spectrophotometer. Dye uptake (%) = (A0 - A t ) / A0 × 100%; Here, A0 represents the absorbance value of the characteristic absorption peak of the dye before treatment, and A t represents the absorbance value of the dye at the treatment time t.

[0043] (9) Soap Fastness: Soap The fastness is measured in accordance with the national standard GB / T3921.1-1997.

[0044] (10) Relative viscosity: The relative viscosity of the polyamide 5X resin is measured with concentrated sulfuric acid using an Ubbelohde viscometer. The procedure is as follows: Precisely weigh 0.25 ± 0.0002 g of a dried polyamide 5X resin sample; add 50 mL of concentrated sulfuric acid (96%) and dissolve it. Measure and record the flow time t0 of the concentrated sulfuric acid and the flow time t of the solution of the polyamide 5X continuous bulked filament in a water bath at a constant temperature of 25°C. The relative viscosity is calculated according to the following formula: Relative viscosity VN = t / t0; t represents the flow time of the solution, and t0 represents the flow time of the solvent.

[0045] (11) Moisture content: The moisture content is measured by a Karl Fischer moisture titration device.

[0046] The water-soluble polyester COPET is commercially available from Puyuan Chemical Fiber Co., Ltd. (Shanghai). The polyester COPET is of fiber grade and has an intrinsic viscosity of 0.6 - 0.8. Polyamide 56 chips with a relative viscosity of 2.4 - 3.0 are commercially available from Kaisai (Jinxiang) Biomaterials Co., Ltd. Polyamide 6 chips with a relative viscosity of 2.5 - 2.7 are commercially available from Ruimeifu Industrial Co., Ltd. (Jiangsu). Polyamide 66 chips with a relative viscosity of 2.4 - 2.7 are commercially available from Shenma Plastic Technology Co., Ltd. (Pingdingshan). Polyethylene resin with a melt index of 10 - 80 g / 10 min is commercially available from Yanshan Petrochemical Co., Ltd. (Beijing).

[0047] Example 1 This example provides a method for manufacturing polyamide 56 / polyethylene sea-island fibers, which includes the following steps: 1) Dry the island component polyamide 56 resin and the sea component polyethylene resin respectively; after drying, control the moisture content of the island component to 800 ppm and adjust the moisture content of the sea component to 60 ppm;

[0048] 2) Heat and melt the island component resin and the sea component resin at a certain ratio respectively. Here, the mass ratio of the island component to the sea component in the island-sea fiber is 70:30; transport the above two melts to the spinning beam through pipes; precisely measure each melt with a metering pump and inject it into the sea-island composite material spinning pack in the spinning beam; after being distributed through the distribution pipes in the spinning pack, converge and extrude the two melts at the inlet of the spinneret orifice; and

[0049] 3) Cool the extruded as-formed fibers, finish spinning, draw, heat set, wind up, Fixed to obtain sea-island fibers.

[0050] Fixed The number of islands in the monofilament of the sea-island fiber was 51, and the fiber had a circular cross-section.

[0051] In step 1), the relative viscosity of the island component polyamide 56 resin was 2.5.

[0052] In step 2), the heating was carried out in a screw extruder, where the screw extruder included five zones for heating: For the screw for the island component: the temperature of the first zone was 230 °C, the temperature of the second zone was 250 °C, the temperature of the third zone was 270 °C, the temperature of the fourth zone was 290 °C, and the temperature of the fifth zone was 285 °C; For the screw for the sea component: the temperature of the first zone was 120 °C, the temperature of the second zone was 140 °C, the temperature of the third zone was 160 °C, the temperature of the fourth zone was 180 °C, and the temperature of the fifth zone was 220 °C;

[0053] In step 2), the temperature of the spinning beam was 280 °C; the spinning pack pressure of the island component was 13.0 MPa; the spinning pack pressure of the sea component was 11.0 MPa; and the difference in spinning pack pressure between the sea component and the island component was controlled to be 4.0 MPa or less.

[0054] In step 3), the above cooling was carried out by quench air, the air velocity was 0.5 m / s, the air temperature was 23 °C, and the oil pick-up calculated based on the weight of the fiber was 0.3 wt%. The as-spun formed yarn was directed towards the hot draw roller through the feed roller for drawing. The draw ratio was 3.0, Heat set the temperature was 180 °C, and the winding speed was 3500 m / min.

[0055] For the splitting process of the sea-island fiber, the solvent was xylene, the splitting temperature was 70 °C, the splitting time was 30 minutes, the bath ratio was 1:30, and the weight loss of the fiber was 29 wt%.

[0056] The test data of the obtained sea-island fiber are shown in Table 1.

[0057] Example 2 This example provided a method for manufacturing polyamide 56 / low-density polyethylene sea-island fiber, including the following steps: 1) Drying the island component polyamide 56 resin and the sea component low-density polyethylene resin respectively; after drying, controlling the moisture content of the island component to 1000 ppm and adjusting the moisture content of the sea component to 90 ppm;

[0058] 2) Heating and melting the island component resin and the sea component resin at a certain ratio respectively, where the mass ratio of the island component to the sea component in the island-sea fiber was 60:40; transporting the above two melts to the spinning beam through a pipe; precisely metering each melt with a metering pump and injecting it into the sea-island composite material spinning pack in the spinning beam; after being distributed through the distribution pipe in the spinning pack, converging and extruding the two melts at the inlet of the spinneret orifice; and

[0059] 3) Cool the extruded as-formed fibers, finish spinning, draw, heat set, wind up, Fixed to obtain sea-island fibers.

[0060] Fixed The number of islands in the monofilament of the sea-island fiber was 37, and the fiber had a circular cross-section.

[0061] In step 1), the relative viscosity of the island component polyamide 56 resin was 2.8.

[0062] In step 2), the heating was carried out in a screw extruder, where the screw extruder included five zones for heating: For the screw for the island component: the temperature of the first zone was 240 °C, the temperature of the second zone was 260 °C, the temperature of the third zone was 280 °C, the temperature of the fourth zone was 290 °C, and the temperature of the fifth zone was 280 °C; For the screw for the sea component: the temperature of the first zone was 120 °C, the temperature of the second zone was 150 °C, the temperature of the third zone was 180 °C, the temperature of the fourth zone was 190 °C, and the temperature of the fifth zone was 210 °C;

[0063] In step 2), the temperature of the spinning beam was 270 °C; the spinning pack pressure of the island component was 14.0 MPa; the spinning pack pressure of the sea component was 13.0 MPa; the difference in spinning pack pressure between the sea component and the island component was controlled to be 4.0 MPa or less.

[0064] In step 3), the above cooling was carried out by quench air, the air speed was 0.3 m / s, the air temperature was 22 °C, and the oil pickup calculated based on the weight of the fiber was 0.6% by weight; The as-formed yarn after spinning finish was directed through a supply roller towards a hot draw roller for drawing. The draw ratio was 3.2, Heat set the temperature was 120 °C, and the winding speed was 4000 m / min.

[0065] The splitting process of the sea-island fiber was as follows: the solvent was toluene, the splitting temperature was 80 °C, the splitting time was 40 minutes, the bath ratio was 1:40, and the weight loss of the fiber was 38 wt%.

[0066] The test data of the obtained sea-island fiber are shown in Table 1.

[0067] Example 3 This example provided a method for manufacturing polyamide 56 / water-soluble polyester sea-island fiber, including the following steps: 1) Drying the island component polyamide 56 resin and the sea component water-soluble polyester resin respectively; after drying, controlling the moisture content of the island component to 500 ppm and adjusting the moisture content of the sea component to 30 ppm;

[0068] 2) Heating and melting the island component resin and the sea component resin at a certain ratio respectively. Here, the mass ratio of the island component to the sea component in the island-sea fiber was 80:20; transporting the above two melts to the spinning beam through pipes; precisely metering each melt with a metering pump and injecting it into the sea-island composite material spinning pack in the spinning beam; after being distributed through the distribution pipe in the spinning pack, converging and extruding the two melts at the entrance of the spinneret orifice; and

[0069] 3) Cooling the extruded as-formed fiber, finishing the spinning, stretching, heat setting, winding, Fixed to obtain the island-type sea-island fiber.

[0070] Fixed The number of islands in the monofilament of the island-type sea-island fiber was 37, and the fiber had a circular cross-section.

[0071] In step 1), the relative viscosity of the island component polyamide 56 resin was 2.8.

[0072] In step 2), the heating was carried out in a screw extruder, where the screw extruder included five zones for heating: For the island component screw: the temperature of the first zone was 240°C, the temperature of the second zone was 260°C, the temperature of the third zone was 280°C, the temperature of the fourth zone was 290°C, and the temperature of the fifth zone was 290°C; For the sea component screw: the temperature of the first zone was 180°C, the temperature of the second zone was 220°C, the temperature of the third zone was 240°C, the temperature of the fourth zone was 260°C, and the temperature of the fifth zone was 240°C;

[0073] In step 2), the temperature of the spinning beam was 285°C; the spinning pack pressure of the island component was 14.0 MPa; the spinning pack pressure of the sea component was 13.0 MPa; the difference in spinning pack pressure between the sea component and the island component was controlled to be 4.0 MPa or less.

[0074] In step 3), the above cooling was performed by quench air, the air velocity was 0.6 m / s, the air temperature was 25°C, and the oil pickup calculated based on the weight of the fiber was 0.5 wt%; The as-spun yarn was directed through a feed roller towards a hot draw roller for drawing. The draw ratio was 2.5, Heat set the temperature was 160°C, and the winding speed was 2500 m / min.

[0075] For the splitting process of the sea-island fiber, the solvent was a 20 wt% aqueous solution of sodium hydroxide, the splitting temperature was 90°C, the splitting time was 40 minutes, the bath ratio was 1:20, and the weight loss of the fiber was 19 wt%.

[0076] The test data of the obtained sea-island fiber were shown in Table 1.

[0077] Example 4 This example provided a method for manufacturing polyamide 510 / polyethylene sea-island fiber, including the following steps: 1) Dry the island component polyamide 510 resin and the sea component polyethylene resin respectively; after drying, control the moisture content of the island component to 900 ppm and adjust the moisture content of the sea component to 80 ppm;

[0078] 2) The island component resin and the sea component resin are heated and melted at a certain ratio respectively. Here, the mass ratio of the island component to the sea component in the island-sea fiber is 65:35; the above two melts are transported to the spinning beam through a pipe; each melt is precisely metered by a metering pump and injected into the sea-island composite material spinning pack in the spinning beam; after being distributed through the distribution pipe in the spinning pack, the two melts are converged and extruded at the inlet of the spinneret orifice; and,

[0079] 3) The extruded as-formed fibers are cooled, spun-finished, drawn, heat-set, wound up, Fixed to obtain sea-island fibers.

[0080] Fixed The number of islands in the monofilament of the sea-island fiber was 51, and the fiber had a circular cross-section.

[0081] In step 1), the relative viscosity of the island component polyamide 510 resin was 2.6.

[0082] In step 2), the heating was carried out in a screw extruder, where the screw extruder included five zones for heating: For the screw of the island component: the temperature of the first zone was 220 °C, the temperature of the second zone was 230 °C, the temperature of the third zone was 240 °C, the temperature of the fourth zone was 260 °C, and the temperature of the fifth zone was 260 °C; For the screw of the sea component: the temperature of the first zone was 130 °C, the temperature of the second zone was 150 °C, the temperature of the third zone was 170 °C, the temperature of the fourth zone was 180 °C, and the temperature of the fifth zone was 230 °C;

[0083] In step 2), the temperature of the spinning beam was 255 °C; the spinning pack pressure of the island component was 12.0 MPa; the spinning pack pressure of the sea component was 10.0 MPa; the spinning pack pressure difference between the sea component and the island component was controlled to be 4.0 MPa or less.

[0084] In step 3), the above cooling was carried out by quench air, the air velocity was 0.8 m / s, the air temperature was 22 °C, and the oil pickup calculated based on the weight of the fiber was 0.4% by weight; The as-spun formed yarn was directed through a supply roller towards a hot draw roller for drawing. The draw ratio was 2.5, Heat set the temperature was 130 °C, and the winding speed was 3000 m / min.

[0085] For the splitting process of the sea-island fiber, the solvent was xylene, the splitting temperature was 70 °C, the splitting time was 30 minutes, the bath ratio was 1:30, and the weight loss of the fiber was 34% by weight.

[0086] The test data of the obtained sea-island fiber are shown in Table 1.

[0087] Example 5 This example provided a method for manufacturing polyamide 56 / water-soluble polyester non- Fixed island-type sea-island fibers, including the following steps: 1) Drying the island component resin and the sea component resin respectively; after drying, controlling the moisture content of the island component to 800 ppm and adjusting the moisture content of the sea component to 90 ppm;

[0088] 2) After uniformly mixing the above island component and sea component in a certain ratio, heating and melting the mixture, where the mass ratio of the island component to the sea component in the island-sea fiber is 70:30, transporting the above blended melt through a pipe to a spinning beam, precisely metering the above blended melt by a metering pump, injecting it into a single-component spinning pack in the spinning beam, and extruding the above blended melt through a spinneret orifice; and

[0089] 3) Cooling, spin-finishing, drawing, heat-setting, winding, and obtaining non- Fixed island-type sea-island fibers.

[0090] In step 1), the relative viscosity of the island component polyamide 56 resin was 2.7.

[0091] In step 2), the heating was carried out in a screw extruder, where the screw extruder included five zones for heating; The temperature of the first zone was 220°C, the temperature of the second zone was 240°C, the temperature of the third zone was 260°C, the temperature of the fourth zone was 280°C, and the temperature of the fifth zone was 280°C;

[0092] In step 2), the temperature of the spinning beam was 280°C; the spinning pack pressure was 16.0 MPa.

[0093] In step 3), the above cooling was carried out by quench air, the air velocity was 0.4 m / s, the air temperature was 24°C, and the oil pickup calculated based on the weight of the fiber was 0.3 wt%; The as-spun and formed yarn was directed through a feed roller towards a hot draw roller for drawing. The draw ratio was 3.0, Heat set The temperature was 170°C, and the winding speed was 4200 m / min.

[0094] For the splitting process of the sea-island fiber, the solvent was a 3.0 wt% aqueous solution of sodium hydroxide, the splitting temperature was 90°C, the splitting time was 40 minutes, the bath ratio was 1:30, and the weight loss of the fiber was 28 wt%.

[0095] The test data of the obtained sea-island fiber were shown in Table 1.

[0096] Example 6 This example provided a method for manufacturing polyamide 510 / water-soluble polyester non-island sea-island fibers, including the following steps: 1) Drying the island component resin and the sea component resin respectively; after drying, controlling the moisture content of the island component to 700 ppm and adjusting the moisture content of the sea component to 60 ppm;

[0097] 2) After uniformly mixing the above island component and sea component at a certain ratio, the mixture is heated and melted. Here, the mass ratio of the island component to the sea component in the island-sea fiber is 60:40. The blended melt is conveyed through a pipe to a spinning beam, precisely metered by a metering pump, injected into a single-component spinning pack in the spinning beam, and extruded through a spinneret orifice;

[0098] 3) The extruded as-formed fibers are cooled, spun-finished, drawn, heat-set, wound up, and non- Fixed island-type sea-island fibers are obtained.

[0099] In step 1), the relative viscosity of the island component polyamide 510 resin was 2.7.

[0100] In step 2), the heating was carried out in a screw extruder, where the screw extruder included five zones for heating: The temperature of the first zone was 220 °C, the temperature of the second zone was 230 °C, the temperature of the third zone was 260 °C, the temperature of the fourth zone was 270 °C, and the temperature of the fifth zone was 280 °C;

[0101] In step 2), the temperature of the spinning beam was 270 °C; the spinning pack pressure was 14.0 MPa.

[0102] In step 3), the cooling was carried out by quench air, the air velocity was 0.6 m / s, the air temperature was 25 °C, and the oil pickup calculated based on the weight of the fiber was 0.5 wt%; The as-spun-finished yarn was directed through a supply roller towards a hot draw roller for drawing. The draw ratio was 1.5, Heat set the temperature was 180 °C, and the winding speed was 4000 m / min.

[0103] For the splitting process of the sea-island fiber, the solvent was a 5.0 wt% aqueous solution of sodium hydroxide, the splitting temperature was 85 °C, the splitting time was 50 minutes, the bath ratio was 1:20, and the weight loss of the fiber was 38 wt%.

[0104] The test data of the obtained sea-island fiber are shown in Table 1.

[0105] Comparative Example 1 This comparative example provided a method for manufacturing polyamide 6 / polyethylene sea-island fibers, including the following steps: 1) Drying the island component polyamide 6 resin and the sea component polyethylene resin respectively; after drying, controlling the moisture content of the island component to 800 ppm and adjusting the moisture content of the sea component to 60 ppm;

[0106] 2) Heating and melting the island component resin and the sea component resin at a certain ratio respectively. Here, the mass ratio of the island component to the sea component in the island-sea fiber was 70:30; transporting the above two melts to the spinning beam through a pipe; precisely metering each melt with a metering pump and injecting it into the sea-island composite material spinning pack in the spinning beam; after being distributed through the distribution pipe in the spinning pack, converging and extruding the two melts at the inlet of the spinneret orifice; and

[0107] 3) Cooling the extruded as-formed fibers, finishing the spinning, stretching, heat setting, winding, Fixed to obtain sea-island fibers.

[0108] Fixed The number of islands in the monofilament of the sea-island fiber was 51, and the fiber had a circular cross-section.

[0109] In step 1), the relative viscosity of the island component polyamide 6 resin was 2.5.

[0110] In step 2), the heating was carried out in a screw extruder, where the screw extruder included five zones for heating; For the island component screw: the temperature of the first zone was 220 °C, the temperature of the second zone was 230 °C, the temperature of the third zone was 240 °C, the temperature of the fourth zone was 260 °C, and the temperature of the fifth zone was 275 °C; For the sea component screw: the temperature of the first zone was 120 °C, the temperature of the second zone was 140 °C, the temperature of the third zone was 160 °C, the temperature of the fourth zone was 180 °C, and the temperature of the fifth zone was 220 °C;

[0111] In step 2), the temperature of the spinning beam was 250 °C; the spinning pack pressure of the island component was 12.0 MPa; the spinning pack pressure of the sea component was 11.0 MPa; the difference in spinning pack pressure between the sea component and the island component was controlled to be 4.0 MPa or less.

[0112] In step 3), the above cooling was carried out by quench air, the air speed was 0.5 m / s, the air temperature was 23 °C, and the oil pickup calculated based on the weight of the fiber was 0.3 wt%; The as-spun formed yarn was directed through a feed roller towards a hot draw roller for drawing. The draw ratio was 3.0, Heat set The temperature was 180 °C, and the winding speed was 3500 m / min.

[0113] For the splitting process of the sea-island fiber, the solvent was xylene, the splitting temperature was 70 °C, the splitting time was 30 minutes, the bath ratio was 1:30, and the weight loss of the fiber was 28 wt%.

[0114] The test data of the obtained sea-island fiber were shown in Table 1.

[0115] Comparative Example 2 This comparative example provided a method for manufacturing polyamide 6 / water-soluble polyester non-island sea-island fibers, including the following steps: 1) Drying the island component resin and the sea component resin respectively; after drying, controlling the moisture content of the island component to 800 ppm and adjusting the moisture content of the sea component to 90 ppm;

[0116] 2) After uniformly mixing the above island component and sea component at a certain ratio, the mixture is heated and melted. Here, the mass ratio of the island component to the sea component in the island-sea fiber is 70:30. The blended melt is conveyed through a pipe to a spinning beam, precisely metered by a metering pump, injected into a single-component spinning pack in the spinning beam, and extruded through a spinneret orifice; and,

[0117] 3) The extruded as-formed fibers are cooled, spun to finish, drawn, heat-set, wound up, non Fixed island-type sea-island fibers are obtained.

[0118] In step 1), the relative viscosity of the island component polyamide 6 resin was 2.7.

[0119] In step 2), the heating was carried out in a screw extruder, where the screw extruder included five zones for heating: The temperature of the first zone was 220 °C, the temperature of the second zone was 240 °C, the temperature of the third zone was 250 °C, the temperature of the fourth zone was 260 °C, and the temperature of the fifth zone was 260 °C;

[0120] In step 2), the temperature of the spinning beam was 260 °C; the spinning pack pressure was 12.0 MPa.

[0121] In step 3), the above cooling was carried out by quench air, the air speed was 0.4 m / s, the air temperature was 24 °C, and the oil pickup calculated based on the weight of the fiber was 0.3 wt%; The as-spun as-formed yarn was directed through a supply roller towards a hot draw roller for drawing. The draw ratio was 3.0, Heat set the temperature was 170 °C, and the winding speed was 4200 m / min.

[0122] For the splitting process of the sea-island fiber, the solvent was an aqueous solution of 3.0 wt% sodium hydroxide, the splitting temperature was 90 °C, the splitting time was 40 minutes, the bath ratio was 1:30, and the weight loss of the fiber was 28 wt%.

[0123] The test data of the obtained sea-island fiber are shown in Table 1.

[0124] Comparative Example 3 This comparative example provided a method for manufacturing polyamide 66 / water-soluble polyester non-sea-island fiber, including the following steps: 1) Drying the island component resin and the sea component resin respectively; after drying, controlling the moisture content of the island component to 800 ppm and adjusting the moisture content of the sea component to 90 ppm;

[0125] 2) After uniformly mixing the above-mentioned island component and sea component at a certain ratio, heating and melting the mixture. Here, the mass ratio of the island component to the sea component in the island-sea fiber was 70:30. Conveying the above-mentioned blended melt through a pipe to a spinning beam, precisely metering the above-mentioned blended melt by a metering pump, injecting it into a single-component spinning pack in the spinning beam, and extruding the above-mentioned blended melt through a spinneret orifice; and

[0126] 3) Cooling the extruded as-formed fiber, finishing the spinning, stretching, heat setting, winding, and obtaining non-sea-island fiber. Fixed Obtaining non-sea-island fiber.

[0127] In step 1), the relative viscosity of the island component polyamide 66 resin was 2.7.

[0128] In step 2), the heating was carried out in a screw extruder, where the screw extruder included five zones for heating: The temperature of the first zone was 230 °C, the temperature of the second zone was 250 °C, the temperature of the third zone was 270 °C, the temperature of the fourth zone was 280 °C, and the temperature of the fifth zone was 290 °C;

[0129] In step 2), the temperature of the spinning beam was 290 °C; the spinning pack pressure was 13.0 MPa.

[0130] In step 3), the above cooling was carried out by quench air, the air speed was 0.4 m / s, the air temperature was 24 °C, and the oil pickup calculated based on the weight of the fiber was 0.3 wt%; The as-spun formed yarn was directed through supply rollers towards a hot draw roller for drawing. The draw ratio was 3.0, Heat set the temperature was 170 °C, and the winding speed was 4200 m / min.

[0131] For the splitting process of the sea-island fiber, the solvent was a 3.0 wt% aqueous solution of sodium hydroxide, the splitting temperature was 90 °C, the splitting time was 40 minutes, the bath ratio was 1:30, and the weight loss of the fiber was 28 wt%.

[0132] The test data of the obtained sea-island fiber were shown in Table 1.

[0133] Comparative Example 4 This comparative example provided a method for manufacturing polyamide 56 / water-soluble polyester Fixed island-type sea-island fiber, including the following steps: Using polyamide 56 as the island component polymer and water-soluble polyester as the sea component polymer, melting them respectively, metering with a metering pump, putting them into a spinning machine at a spinning temperature of 298 °C, setting the overall ratio of the sea component to the island component to 20 / 80, introducing the melts of the sea component and the island component into a sea-island component composite spinning pack, and then extruding from a spinneret. Cooling the yarn spun from the spinneret with an air cooling device. After finishing spinning the yarn, winding it onto an unrefined 175 dtex - 112 filament with a winding machine at a speed of 1500 m / min; Subsequently, stretching the filament with a stretching device at a speed of 300 m / min, controlling the elongation at 20 - 40% to obtain a stretched yarn of 66 dtex - 112 filament, and immersing the obtained sea-island composite fiber in a 1 wt% aqueous solution of sodium hydroxide at 80 °C to remove the sea component by dissolution.

[0134] The test data of the obtained sea-island fibers are shown in Table 1.

[0135] JPEG0007702939000002.jpg160170

[0136] The polyamide sea-island fibers prepared in Examples 1 to 6 of the present invention had a lower initial elastic modulus compared to those prepared in Comparative Examples 1 to 3. Therefore, the polyamide sea-island fibers produced in Examples 1 to 6 had better softness. In addition, the polyamide sea-island fibers of the present invention had good dyeability. Also, the polyamide sea-island fibers prepared in Examples 1 to 6 were significantly better than those prepared in Comparative Examples 1 to 3 in terms of dye uptake, dyeing gray scale, dyeing depth, and color fastness.

[0137] Therefore, the polyamide sea-island fiber monofilaments produced according to the present invention are finer, have a soft and delicate touch. The bending rigidity is significantly reduced, the gloss is soft, the fiber specific surface area is large, and the structure is of high density. The polyamide sea-island fiber single fibers produced according to the present invention are suitable for use in fields such as artificial hair, imitation silk, artificial leather, artificial peach skin, artificial suede, high-density waterproof cloth, high-performance washing clothing, high-performance adsorption / filtration materials, high oil-absorbing materials, high water-absorbing materials, heat insulation materials, medical materials, automobile equipment materials, safety shoes, cases, handbags, sofas, etc.

[0138] Finally, it should be noted that the above embodiments are only used to explain the technical solutions of the present invention and are not intended to limit them. As described above, the present invention has been described in detail using the above embodiments. However, those skilled in the art should understand that it is possible to further modify the technical solutions described in the above embodiments, or to equally replace some or all of their technical features. By these changes or replacements, the gist of the corresponding technical solutions does not deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polyamide sea-island fiber, wherein the raw material of the island component is a polyamide resin selected from one of polyamide 56, polyamide 510, polyamide 511, polyamide 512, polyamide 513, polyamide 514, polyamide 515, and polyamide 516, and the sea component is one of polyethylene, low-density polyethylene, polystyrene, water-soluble polyester, polyester, and polyurethane; the polyamide resin has a relative viscosity of 2.4 to 3.0; the polyamide sea-island fiber has a fineness of 10 to 300 dtex; the polyamide sea-island fiber is characterized by having an initial elastic modulus of 20 to 50 cN / dtex.

2. The polyamide sea-island fiber according to Claim 1, wherein the polyamide resin is selected from the group consisting of super bright polyamide resin, semi-dull polyamide resin, full dull polyamide resin, and mixtures thereof; and / or the polyamide resin has a relative viscosity of 2.5 to 2.9; and / or the mass ratio of the island component to the sea component of the sea-island fiber is 20 to 80:80 to 20.

3. The polyamide sea-island fiber according to Claim 1 or 2, wherein the sea-island fiber is a fixed island type sea-island fiber or a non-fixed island type sea-island fiber; and / or the number of islands in the fixed island type sea-island fiber is 16 to 500.

4. The polyamide sea-island fiber according to any one of Claims 1 to 3, wherein the polyamide sea-island fiber has a fineness of 20 to 200 dtex; and / or the polyamide sea-island fiber has a breaking strength of 2.0 to 5.0 cN / dtex; and / or the polyamide sea-island fiber has an elongation at break of 30 to 80%; and / or the polyamide sea-island fiber has an initial elastic modulus of 23 to 45 cN / dtex; and / or after being split, the polyamide sea-island fiber has a monofilament fineness of 0.001 to 0.2 dtex; and / or the polyamide sea-island fiber is characterized by having a dyeing uniformity (gray scale) of grade 3.5 or higher.

5. The polyamide sea-island fiber according to any one of Claims 1 to 4, wherein The polyamide sea-island fiber has a fineness of 30 to 100 dtex; and / or The polyamide sea-island fiber has a breaking strength of 2.5 to 4.5 cN / dtex; and / or The polyamide sea-island fiber has an elongation at break of 40 to 70%; and / or The polyamide sea-island fiber has an initial modulus of 28 to 38 cN / dtex; and / or After the polyamide sea-island fiber is split, it has a monofilament fineness of 0.005 to 0.1 dtex, and / or The polyamide sea-island fiber is characterized by having a dyeing uniformity (gray scale) of grade 4.5 or higher.

6. A method for manufacturing a fixed-island type sea-island fiber according to claim 3, comprising the following steps: 1) Heating and melting the island component resin and the sea component resin respectively to obtain two melts; transporting the two melts through a pipe to a spinning beam; accurately metering each melt with a metering pump and injecting it into a sea-island type composite material spinning pack in the spinning beam; distributing the two melts through a distribution pipe of the spinning pack, converging and extruding them at the inlet of a spinneret orifice; the moisture content of the island component is less than 1500 ppm, and the moisture content of the sea component is less than 300 ppm; and 2) Cooling, spinning, stretching, heat setting, and winding up the as-formed fibers extruded in step 1) to obtain the fixed-island type sea-island fiber. including In step 1), The heating is carried out by a screw extruder, and the screw extruder includes five zones for heating; For the screw of the island component, the temperature of the first zone is 200 to 260 °C, the temperature of the second zone is 230 to 280 °C, the temperature of the third zone is 240 to 290 °C, the temperature of the fourth zone is 260 to 300 °C, and the temperature of the fifth zone is 270 to 310 °C; For the screw of the sea component, the temperature of the first zone is 120 to 220 °C, the temperature of the second zone is 140 to 240 °C, the temperature of the third zone is 160 to 260 °C, the temperature of the fourth zone is 180 to 280 °C, and the temperature of the fifth zone is 160 to 290 °C.

7. A method according to claim 6, wherein In step 1), The temperature of the spinning beam is 200 to 300 °C; and / or The spinning pack pressure of the island component is 10.0 to 15.0 MPa, and the spinning pack pressure of the sea component is 8.0 to 15.0 MPa; and the difference in spinning pack pressure between the sea component and the island component is controlled to be less than 4.0 MPa.

8. The method according to claim 6 or 7, In step 2), the cooling is performed by quench air or cross air blow, the air velocity is 0.2 to 1.2 m / s, the air temperature of the quench air is 15 to 30 °C, and / or the oil pickup is 0.2 to 1.0% by weight, and / or the drawing process is that the as-spun formed yarn is directed through a supply roller towards a hot drawing roller for drawing, and the draw ratio is 2.0 to 5.0; and / or the temperature of the heat setting is 150 to 220 °C; and / or the winding speed is 1000 to 6000 m / min A method characterized by the above.

9. The method according to claim 8, the air velocity is 0.2 to 1.0 m / s, the air temperature of the quench air is 20 to 27 °C, and / or the oil pickup is 0.3 to 0.8% by weight, and / or the draw ratio is 2.5 to 3.0; and / or the temperature of the heat setting is 160 to 200 °C; and / or the winding speed is 2000 to 5000 m / min. A method characterized by the above.

10. A method for manufacturing a non-fixed island-type sea-island fiber according to claim 3, comprising the following steps: a) uniformly mixing the island component and the sea component at a certain ratio, then heating and melting the mixture; conveying the obtained blended melt through a pipe to a spinning beam; precisely metering the blended melt by a metering pump and injecting it into a single-component spinning pack in the spinning beam; extruding the blended melt through a spinneret orifice; here, the island component has a moisture content of less than 1500 ppm; the sea component has a moisture content of less than 300 ppm; b) cooling the extruded as-formed fiber, spin-finishing, drawing, heat-setting, winding to obtain the non-fixed island-type sea-island fiber. Including, In step a), The heating is carried out in a screw extruder, the screw extruder including five zones for heating; the temperature of the first zone being 180 to 240 °C; the temperature of the second zone being 200 to 260 °C; the temperature of the third zone being 220 to 270 °C; the temperature of the fourth zone being 240 to 280 °C; and the temperature of the fifth zone being 200 to 300 °C, a method characterized thereby.

11. The method according to claim 10, wherein in step a), the temperature of the spinning beam is 200 to 300 °C; and the spinning pack pressure is 10.0 to 25.0 MPa, a method.

12. The method according to claim 10 or 11, wherein in step b), the cooling is carried out by quench air or cross air blow; the air velocity is 0.2 to 1.2 m / s, the air temperature of the quench air being 15 to 30 °C; and / or the oil pickup is 0.2 to 1.0 wt%; and / or the drawing process is that the as-spun formed yarn is directed through supply rollers towards a hot drawing roller for drawing, the draw ratio being 2.0 to 5.0; and / or the temperature of the heat setting is 150 to 220 °C; and / or the winding speed is 1000 to 6000 m / min, a method.

13. The method according to claim 12, wherein the air velocity is 0.4 to 1.0 m / s, the air temperature of the quench air being 23 to 27 °C; and / or the oil pickup is 0.3 to 0.8 wt%; and / or the draw ratio is 2.5 to 3.0; and / or the temperature of the heat setting is 160 to 200 °C; and / or the winding speed is 2000 to 5000 m / min, a method.

14. Use of the polyamide sea-island fiber according to any one of claims 1 to 5 in the manufacture of artificial hair, imitation silk, artificial leather, artificial peach skin, artificial suede, high-density waterproof fabric, high-performance laundry, high-performance adsorption and filtration materials, high oil-absorbing materials, high water-absorbing materials, heat insulation materials, medical materials, automotive equipment materials, safety boots, cases, handbags or sofas.

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