POLYAMIDE SEA-ISLAND FIBER, PREPARATION METHOD THEREFOR, AND USE THEREOF

Abstract

The present invention relates to the technical field of polyamide materials, and specifically relates to a polyamide sea-island fiber and a process for producing the same and the use thereof. In the polyamide sea-island 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; the sea component is one of polyethylene, low-density polyethylene, polystyrene, water-soluble polyesters, polyesters and polyurethanes, preferably polyethylene, low-density polyethylene or water-soluble polyester. The polyamide sea-island fiber of the present invention has better mechanical properties, better softness, good dyeing properties, high grade of dyeing grey scale, high dye uptake, high dyeing depth and high color fastness.

Claims

1. A polyamide sea-island fiber, characterized in that an 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; a sea component is one of polyethylene, low-density polyethylene, polystyrene, water-soluble polyesters, polyesters and polyurethanes, preferably polyethylene, low-density polyethylene or water-soluble polyesters.

2. The polyamide sea-island fiber according to claim 1, characterized in that the island component is selected from the group consisting of super bright polyamide resins, semi dull polyamide resins, full dull polyamide resins and mixtures thereof; and/or the island component polyamide resin has a relative viscosity of 2.4-3.0, preferably 2.5-2.9, and more preferably 2.6-2.8; and/or the mass ratio of the island component to the sea component of the sea-island fiber is 20-80:80-20, and more preferably 30-70:70-30.

3. The polyamide sea-island fiber according to claim 1, characterized in that the sea-island fiber includes a figured sea-island fiber and an unfigured sea-island fiber; and/or the number of the islands in the figured sea-island fiber is 16-500.

4. The polyamide sea-island fiber according to claim 1, characterized in that the polyamide sea-island fiber has a fineness of 10-300 dtex, preferably 20-200 dtex, and more preferably 30-100 dtex; and/or the polyamide sea-island fiber has a break strength of 2.0-5.0 cN/dtex, preferably 2.5-4.5 cN/dtex, and more preferably 3.0-4.0 cN/dtex; and/or the polyamide sea-island fiber has an elongation at break of 30-80%, preferably 40-70%, and more preferably 45-60%; and/or the polyamide sea-island fiber has an initial modulus of 20-50 cN/dtex, preferably 23-45 cN/dtex, and more preferably 28-38 cN/dtex; and/or after the polyamide sea-island fiber is split, the island component has a monofilament fineness of 0.001-0.2 dtex, preferably 0.005-0.1 dtex, and more preferably 0.01-0.05 dtex; and/or the polyamide sea-island fiber has a K/S value of 15 or more, preferably 20 or more, and more preferably 25 or more; and/or the polyamide sea-island fiber has a dye uptake of 90% or more, preferably 93% or more, and more preferably 96% or more; and/or the polyamide sea-island fiber has a dyeing uniformity (grey scale) of grade 3.5 or more, preferably grade 4.0 or more, and more preferably grade 4.5 or more; and/or the polyamide sea-island fiber has a soap fastness for fading of grade 3.0 or more, preferably grade 3.5 or more, more preferably grade 4.0 or more; and still more preferably 4.5 or more; and/or the polyamide sea-island fiber has a soap fastness for staining of grade 3.0 or more, preferably grade 3.5 or more, more preferably grade 4.0 or more, and still more preferably grade 4.5 or more.

5. A process for producing the figured sea-island fiber according to claim 3, characterized in that the process comprises the steps of: 1. heating and melting the island component resin and the sea component resin respectively to obtain two melts; conveying the two melts into a spinning beam through a pipe; precisely metering each melt by a metering pump respectively, and injecting them into a sea-island type of composite spin pack in the spinning beam; distributing the two melts via a distribution pipe in the spin pack, and converging and extruding them at the entrance of a spinneret orifice; wherein the island component has a moisture content of less than 1500 ppm, and the sea component has a moisture content of less than 300 ppm; and 2. cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber that is extruded in Step 1), so as to obtain the figured sea-island fiber.

6. The process according to claim 5, characterized in that, in Step 1), the heating is performed in a screw extruder, wherein the screw extruder preferably includes five zones for heating; for a screw for the island component, the temperature of a first zone is 200-260° C.; the temperature of a second zone is 230-280° C.; the temperature of a third zone is 240-290° C.; the temperature of a fourth zone is 260-300° C.; and the temperature of a fifth zone is 270-310° C.; for a screw for the sea component, the temperature of a first zone is 120-220° C.; the temperature of a second zone is 140-240° C.; the temperature of a third zone is 160-260° C.; the temperature of a fourth zone is 180-280° C.; and the temperature of a fifth zone is 160-290° C.; and/or the temperature of the spinning beam is 200-300° C.; and/or the spin pack pressure of the island component is 10.0-15.0 MPa; the spin pack pressure of the sea component is 8.0-15.0 MPa; and the spin pack pressure difference between the sea component and the island component is controlled to be less than 4.0 MPa.

7. The process according to claim 5, characterized in that, in Step 2), the cooling is conducted by quench air or cross air blow; an air speed is 0.2-1.2 m/s, preferably 0.2-1.0 m/s, and more preferably 0.3-0.8 m/s; the air temperature of the quench air is 15-30° C., preferably 20-27° C., and more preferably 22-25° C.; and/or an oil pick up is 0.2-1.0 wt %, preferably 0.3-0.8 wt %, and more preferably 0.4-0.6 wt %; and/or the drawing process is that the as-formed yarn that has been spinning finished is directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio is preferably 2.0-5.0, and more preferably 2.5-3.0; and/or the heat setting temperature is 150-220° C., preferably 160-200° C., and more preferably 170-180° C.; and/or the winding speed is 1000-6000 m/min, preferably 2000-5000 m/min, and more preferably 2500-4000 m/min.

8. A process for producing the unfigured sea-island fiber according to claim 3, characterized in that the process comprises the steps of: a) uniformly mixing the island component and the sea component in a certain proportion and then heating and melting the mixture; conveying the resultant blended melt into a spinning beam through a pipe; precisely metering the blended melt by a metering pump, and injecting it into a one-component spin pack in the spinning beam; and extruding the blended melt through a spinneret orifice; wherein the island component has a moisture content of less than 1500 ppm; and the sea component has a moisture content of less than 300 ppm; 2. cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber that is extruded to obtain the unfigured sea-island fiber.

9. The process according to claim 8, wherein in Step a), the heating is performed in a screw extruder, wherein the screw extruder preferably includes five zones for heating; the temperature of a first zone is 180-240° C.; the temperature of a second zone is 200-260° C.; the temperature of a third zone is 220-270° C.; the temperature of a fourth zone is 240-280° C.; and the temperature of a fifth zone is 200-300° C.; and/or the temperature of the spinning beam is 200-300° C.; and the spin pack pressure is 10.0-25.0 MPa.

10. The process according to claim 8, wherein in Step b), the cooling is conducted by quench air or cross air blow; the air speed is 0.2-1.2 m/s, preferably 0.4-1.0 m/s, and more preferably 0.6-0.8 m/s; the air temperature of the quench air is 15-30° C., preferably 23-27° C., and more preferably 24-25° C.; and/or the oil pick up is 0.2-1.0 wt %, preferably 0.3-0.8 wt %, and more preferably 0.4-0.6 wt %; and/or the drawing process is that the as-formed yarn that has been spinning finished is directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio is preferably 2.0-5.0, and more preferably 2.5-3.0; and/or the heat setting temperature is 150-220° C., preferably 160-200° C., and more preferably 170-180° C.; and/or the winding speed is 1000-6000 m/min, preferably 2000-5000 m/min, and more preferably 2500-4000 m/min.

11. Use of the polyamide sea-island fiber according to claim 1 in the manufacture of imitation wools, imitation silks, imitation leathers, imitation peach skins, imitation suedes, high-density waterproof fabrics, high-performance cleaning clothes, high-performance adsorbing and filtering materials, highly oil absorptive materials, highly water absorptive materials, thermal insulation materials, medical materials, automotive trim materials, safety shoes, cases, handbags or sofas.

Description

EXAMPLE 1

[0089] The present Example provided a process for producing a polyamide 56/polyethylene figured sea-island fiber, comprising the following steps:

[0090] 1) drying the island component polyamide 56 resin and the sea component polyethylene resin respectively; after drying, controlling the moisture content of the island component at 800 ppm, and controlling the moisture content of the sea component at 60 ppm;

[0091] 2) heating and melting the island component resin and the sea component resin in a certain proportion respectively, wherein the mass ratio of the island component to the sea component in the island-sea fiber was 70:30; conveying the two melts to a spinning beam through a pipe; precisely metering each melt by a metering pump respectively, and injecting them into a sea-island type of composite spin pack in the spinning beam; converging and extruding the two melts at the entrance of the spinneret orifice after being distributed via a distribution pipe in the spin pack; and 3) cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber that is extruded, so as to obtain the figured sea-island fiber.

[0092] The number of islands in a monofilament of the figured sea-island fiber was 51, and the fiber has a circular cross section.

[0093] In Step 1), the relative viscosity of the island component polyamide 56 resin was 2.5.

[0094] In Step 2), the heating was performed in a screw extruder, wherein the screw extruder included five zones for heating;

[0095] 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.;

[0096] 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.;

[0097] in Step 2), the temperature of the spinning beam was 280° C.; the spin pack pressure of the island component was 13.0 MPa; the spin pack pressure of the sea component was 11.0 MPa; and the spin pack pressure difference between the sea component and the island component was controlled to be less than 4.0 MPa.

[0098] In step 3), the cooling was conducted by quench air; the air speed was 0.5 m/s; the air temperature was 23° C.; the oil pick up was 0.3 wt %, which was calculated based on the weight of the fiber;

[0099] the as-formed yarn that has been spinning finished was directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio was 3.0, the heat setting temperature was 180° C.; and the winding speed was 3500 m/min.

[0100] The splitting process of the sea-island fiber was as follows: the solvent was xylene; the splitting temperature was 70° C.; the splitting time was 30 mins; the bath ratio was 1:30; and the weight loss of the fiber was 29 wt %.

[0101] The test data of the sea-island fibers obtained were shown in Table 1.

EXAMPLE 2

[0102] The present Example provided a process for producing a polyamide 56/low-density polyethylene figured sea-island fiber, comprising the following steps:

[0103] 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 at 1000 ppm, and controlling the moisture content of the sea component at 90 ppm;

[0104] 2) heating and melting the island component resin and the sea component resin in a certain proportion respectively, wherein the mass ratio of the island component to the sea component in the island-sea fiber was 60:40; conveying the two melts to a spinning beam through a pipe; precisely metering each melt by a metering pump respectively, and injecting them into a sea-island type of composite spin pack in the spinning beam; converging and extruding the two melts at the entrance of the spinneret orifice after being distributed via a distribution pipe in the spin pack; and 3) cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber that is extruded, so as to obtain the figured sea-island fiber.

[0105] The number of islands in a monofilament of the figured sea-island fiber was 37, and the fiber has a circular cross section.

[0106] In Step 1), the relative viscosity of the island component polyamide 56 resin was 2.8.

[0107] In Step 2), the heating was performed in a screw extruder, wherein the screw extruder included five zones for heating;

[0108] 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.;

[0109] 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.;

[0110] in Step 2), the temperature of the spinning beam was 270° C.; the spin pack pressure of the island component was 14.0 MPa; the spin pack pressure of the sea component was 13.0 MPa; and the spin pack pressure difference between the sea component and the island component was controlled to be less than 4.0 MPa.

[0111] In step 3), the cooling was conducted by quench air; the air speed was 0.3 m/s; the air temperature was 22° C.; the oil pick up was 0.6 wt %, which was calculated based on the weight of the fiber;

[0112] the as-formed yarn that has been spinning finished was directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio was 3.2, the heat setting temperature was 120° C.; and the winding speed was 4000 m/min.

[0113] 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 mins; the bath ratio was 1:40; and the weight loss of the fiber was 38 wt %.

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

EXAMPLE 3

[0115] The present Example provided a process for producing a polyamide 56/water soluble polyester figured sea-island fiber, comprising the following steps:

[0116] 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 at 500 ppm, and controlling the moisture content of the sea component at 30 ppm;

[0117] 2) heating and melting the island component resin and the sea component resin in a certain proportion respectively, wherein the mass ratio of the island component to the sea component in the island-sea fiber was 80:20; conveying the two melts to a spinning beam through a pipe; precisely metering each melt by a metering pump respectively, and injecting them into a sea-island type of composite spin pack in the spinning beam; converging and extruding the two melts at the entrance of the spinneret orifice after being distributed via a distribution pipe in the spin pack; and

[0118] 3) cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber that is extruded, so as to obtain the figured sea-island fiber.

[0119] The number of islands in a monofilament of the figured sea-island fiber was 37, and the fiber has a circular cross section.

[0120] In Step 1), the relative viscosity of the island component polyamide 56 resin was 2.8.

[0121] In Step 2), the heating was performed in a screw extruder, wherein the screw extruder included five zones for heating;

[0122] 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 290° C.;

[0123] for the screw for the sea component: 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.;

[0124] in Step 2), the temperature of the spinning beam was 285° C.; the spin pack pressure of the island component was 14.0 MPa; the spin pack pressure of the sea component was 13.0 MPa; and the spin pack pressure difference between the sea component and the island component was controlled to be less than 4.0 MPa.

[0125] In step 3), the cooling was conducted by quench air; the air speed was 0.6 m/s; the air temperature was 25° C.; the oil pick up was 0.5 wt %, which was calculated based on the weight of the fiber;

[0126] the as-formed yarn that has been spinning finished was directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio was 2.5, the heat setting temperature was 160° C.; and the winding speed was 2500 m/min.

[0127] The splitting process of the sea-island fiber was as follows: the solvent was 20 wt % aqueous solution of sodium hydroxide; the splitting temperature was 90° C.; the splitting time was 40 mins; the bath ratio was 1:20; and the weight loss of the fiber was 19 wt %.

[0128] The test data of the sea-island fibers obtained were shown in Table 1.

EXAMPLE 4

[0129] The present Example provided a process for producing a polyamide 510/polyethylene figured sea-island fiber, comprising the following steps:

[0130] 1) drying the island component polyamide 510 resin and the sea component polyethylene resin respectively; after drying, controlling the moisture content of the island component at 900 ppm, and controlling the moisture content of the sea component at 80 ppm;

[0131] 2) heating and melting the island component resin and the sea component resin in a certain proportion respectively, wherein the mass ratio of the island component to the sea component in the island-sea fiber was 65:35; conveying the two melts to a spinning beam through a pipe; precisely metering each melt by a metering pump respectively, and injecting them into a sea-island type of composite spin pack in the spinning beam; converging and extruding the two melts at the entrance of the spinneret orifice after being distributed via a distribution pipe in the spin pack; and

[0132] 3) cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber that is extruded, so as to obtain the figured sea-island fiber.

[0133] The number of islands in a monofilament of the figured sea-island fiber was 51, and the fiber has a circular cross section.

[0134] In Step 1), the relative viscosity of the island component polyamide 510 resin was 2.6.

[0135] In Step 2), the heating was performed in a screw extruder, wherein the screw extruder included five zones for heating;

[0136] for the screw for 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.;

[0137] for the screw for 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.;

[0138] in Step 2), the temperature of the spinning beam was 255° C.; the spin pack pressure of the island component was 12.0 MPa; the spin pack pressure of the sea component was 10.0 MPa; and the spin pack pressure difference between the sea component and the island component was controlled to be less than 4.0 MPa.

[0139] In step 3), the cooling was conducted by quench air; the air speed was 0.8 m/s; the air temperature was 22° C.; the oil pick up was 0.4 wt %, which was calculated based on the weight of the fiber;

[0140] the as-formed yarn that has been spinning finished was directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio was 2.5, the heat setting temperature was 130° C.; and the winding speed was 3000 m/min.

[0141] The splitting process of the sea-island fiber was as follows: the solvent was xylene; the splitting temperature was 70° C.; the splitting time was 30 mins; the bath ratio was 1:30; and the weight loss of the fiber was 34 wt %.

[0142] The test data of the sea-island fibers obtained were shown in Table 1.

EXAMPLE 5

[0143] The present Example provided a process for producing a polyamide 56/water soluble polyester unfigured sea-island fiber, comprising the following steps:

[0144] 1) drying the island component resin and the sea component resin respectively; after drying, controlling the moisture content of the island component at 800 ppm, and controlling the moisture content of the sea component at 90 ppm;

[0145] 2) uniformly mixing the aforementioned island component and the sea component in a certain proportion and then heating and melting the mixture, wherein the mass ratio of the island component to the sea component in the island-sea fiber was 70:30; conveying the blended melt to a spinning beam through a pipe; precisely metering the blended melt by a metering pump, and injecting it into a one-component spin pack in the spinning beam; and extruding the blended melt through a spinneret orifice; and

[0146] 3) cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber that is extruded to obtain the unfigured sea-island fiber.

[0147] In Step 1), the relative viscosity of the island component polyamide 56 resin was 2.7.

[0148] In Step 2), the heating was performed in a screw extruder, wherein 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.;

[0149] in Step 2), the temperature of the spinning beam was 280° C.; the pressure of the spin pack was 16.0 MPa.

[0150] In step 3), the cooling was conducted by quench air; the air speed was 0.4 m/s; the air temperature was 24° C.; the oil pick up was 0.3 wt %, which was calculated based on the weight of the fiber;

[0151] the as-formed yarn that has been spinning finished was directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio was 3.0, the heat setting temperature was 170° C.; and the winding speed was 4200 m/min.

[0152] The splitting process of the sea-island fiber was as follows: the solvent was 3.0 wt % aqueous solution of sodium hydroxide; the splitting temperature was 90° C.; the splitting time was 40 mins; the bath ratio was 1:30; and the weight loss of the fiber was 28 wt %.

[0153] The test data of the sea-island fibers obtained were shown in Table 1.

EXAMPLE 6

[0154] The present Example provided a process for producing a polyamide 510/water soluble polyester unfigured sea-island fiber, comprising the following steps:

[0155] 1) drying the island component resin and the sea component resin respectively; after drying, controlling the moisture content of the island component at 700 ppm, and controlling the moisture content of the sea component at 60 ppm;

[0156] 2) uniformly mixing the aforementioned island component and the sea component in a certain proportion and then heating and melting the mixture, wherein the mass ratio of the island component to the sea component in the island-sea fiber was 60:40; conveying the blended melt to a spinning beam through a pipe; precisely metering the blended melt by a metering pump, and injecting it into a one-component spin pack in the spinning beam; and extruding the blended melt through a spinneret orifice;

[0157] 3) cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber extruded to obtain the unfigured sea-island fiber.

[0158] In Step 1), the relative viscosity of the island component polyamide 510 resin was 2.7.

[0159] In Step 2), the heating was performed in a screw extruder, wherein 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.;

[0160] in Step 2), the temperature of the spinning beam was 270° C.; the pressure of the spin pack was 14.0 MPa.

[0161] In step 3), the cooling was conducted by quench air; the air speed was 0.6 m/s; the air temperature was 25° C.; the oil pick up was 0.5 wt %, which was calculated based on the weight of the fiber;

[0162] the as-formed yarn that has been spinning finished was directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio was 1.5, the heat setting temperature was 180° C.; and the winding speed was 4000 m/min.

[0163] The splitting process of the sea-island fiber was as follows: the solvent was 5.0 wt % aqueous solution of sodium hydroxide; the splitting temperature was 85° C.; the splitting time was 50 mins; the bath ratio was 1:20; and the weight loss of the fiber was 38 wt %.

[0164] The test data of the sea-island fibers obtained were shown in Table 1.

COMPARATIVE EXAMPLE 1

[0165] The present Comparative Example provided a process for producing a polyamide 6/polyethylene figured sea-island fiber, comprising the following steps:

[0166] 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 at 800 ppm, and controlling the moisture content of the sea component at 60 ppm;

[0167] 2) heating and melting the island component resin and the sea component resin in a certain proportion respectively, wherein the mass ratio of the island component to the sea component in the island-sea fiber was 70:30; conveying the two melts to a spinning beam through a pipe; precisely metering each melt by a metering pump respectively, and injecting them into a sea-island type of composite spin pack in the spinning beam; converging and extruding the two melts at the entrance of the spinneret orifice after being distributed via a distribution pipe in the spin pack; and

[0168] 3) cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber extruded, so as to obtain the figured sea-island fiber.

[0169] The number of islands in a monofilament of the figured sea-island fiber was 51, and the fiber has a circular cross section.

[0170] In Step 1), the relative viscosity of the island component polyamide 6 resin was 2.5.

[0171] In Step 2), the heating was performed in a screw extruder, wherein the screw extruder included five zones for heating;

[0172] for the screw for 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 275° C.;

[0173] 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.;

[0174] in Step 2), the temperature of the spinning beam was 250° C.; the spin pack pressure of the island component was 12.0 MPa; the spin pack pressure of the sea component was 11.0 MPa; and the spin pack pressure difference between the sea component and the island component was controlled to be less than 4.0 MPa.

[0175] In step 3), the cooling was conducted by quench air; the air speed was 0.5 m/s; the air temperature was 23° C.; the oil pick up was 0.3 wt %, which was calculated based on the weight of the fiber;

[0176] the as-formed yarn that has been spinning finished was directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio was 3.0, the heat setting temperature was 180° C.; and the winding speed was 3500 m/min.

[0177] The splitting process of the sea-island fiber was as follows: the solvent was xylene; the splitting temperature was 70° C.; the splitting time was 30 mins; the bath ratio was 1:30; and the weight loss of the fiber was 28 wt %.

[0178] The test data of the sea-island fibers obtained were shown in Table 1.

COMPARATIVE EXAMPLE 2

[0179] The present Comparative Example provided a process for producing a polyamide 6/water soluble polyester unfigured sea-island fiber, comprising the following steps:

[0180] 1) drying the island component resin and the sea component resin respectively; after drying, controlling the moisture content of the island component at 800 ppm, and controlling the moisture content of the sea component at 90 ppm;

[0181] 2) uniformly mixing the aforementioned island component and the sea component in a certain proportion and then heating and melting the mixture, wherein the mass ratio of the island component to the sea component in the island-sea fiber was 70:30; conveying the blended melt to a spinning beam through a pipe; precisely metering the blended melt by a metering pump, and injecting it into a one-component spin pack in the spinning beam; and extruding the blended melt through a spinneret orifice; and 3) cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber extruded, so as to obtain the unfigured sea-island fiber.

[0182] In Step 1), the relative viscosity of the island component polyamide 6 resin was 2.7.

[0183] In Step 2), the heating was performed in a screw extruder, wherein 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.;

[0184] in Step 2), the temperature of the spinning beam was 260° C.; the pressure of the spin pack was 12.0 MPa.

[0185] In step 3), the cooling was conducted by quench air; the air speed was 0.4 m/s; the air temperature was 24° C.; the oil pick up was 0.3 wt %, which was calculated based on the weight of the fiber;

[0186] the as-formed yarn that has been spinning finished was directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio was 3.0, the heat setting temperature was 170° C.; and the winding speed was 4200 m/min.

[0187] The splitting process of the sea-island fiber was as follows: the solvent was 3.0 wt % aqueous solution of sodium hydroxide; the splitting temperature was 90° C.; the splitting time was 40 mins; the bath ratio was 1:30; and the weight loss of the fiber was 28 wt %.

[0188] The test data of the sea-island fibers obtained were shown in Table 1.

COMPARATIVE EXAMPLE 3

[0189] The present Comparative Example provided a process for producing a polyamide 66/water soluble polyester unfigured sea-island fiber, comprising the following steps:

[0190] 1) drying the island component resin and the sea component resin respectively; after drying, controlling the moisture content of the island component at 800 ppm, and controlling the moisture content of the sea component at 90 ppm;

[0191] 2) uniformly mixing the aforementioned island component and the sea component in a certain proportion and then heating and melting the mixture, wherein the mass ratio of the island component to the sea component in the island-sea fiber was 70:30; conveying the blended melt to a spinning beam through a pipe; precisely metering the blended melt by a metering pump, and injecting it into a one-component spin pack in the spinning beam; and extruding the blended melt through a spinneret orifice; and

[0192] 3) cooling, spinning finishing, drawing, heat setting and winding the as-formed fiber extruded to obtain the unfigured sea-island fiber.

[0193] In Step 1), the relative viscosity of the island component polyamide 66 resin was 2.7.

[0194] In Step 2), the heating was performed in a screw extruder, wherein 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.;

[0195] in Step 2), the temperature of the spinning beam was 290° C.; the pressure of the spin pack was 13.0 MPa.

[0196] In step 3), the cooling was conducted by quench air; the air speed was 0.4 m/s; the air temperature was 24° C.; the oil pick up was 0.3 wt %, which was calculated based on the weight of the fiber;

[0197] the as-formed yarn that has been spinning finished was directed to a hot drawing roller through a feeding roller for drawing, and the drawing ratio was 3.0, the heat setting temperature was 170° C.; and the winding speed was 4200 m/min.

[0198] The splitting process of the sea-island fiber was as follows: the solvent was 3.0 wt % aqueous solution of sodium hydroxide; the splitting temperature was 90° C.; the splitting time was 40 mins; the bath ratio was 1:30; and the weight loss of the fiber was 28 wt %.

[0199] The test data of the sea-island fibers obtained were shown in Table 1.

COMPARATIVE EXAMPLE 4

[0200] The present Comparative Example provided a process for producing a polyamide 56/water soluble polyester figured sea-island fiber, comprising the following steps:

[0201] using polyamide 56 as the island component polymer and the water-soluble polyester as the sea component polymer; upon melting and metering with metering pumps respectively, passing them into a spinning die at a spinning temperature of 298° C.; wherein the overall ratio of the sea component to the island component was set at 20/80; introducing the melts of the sea component and the island component into a sea-island composite spinning spin pack and then extruding from the spinneret; cooling the yarns spinning from the spinneret by an air cooling device; after spinning finishing the yarns, winding them into an undrawn 175dtex-112 filament by a winder at a speed of 1500 m/min;

[0202] subsequently, drawing the filament in a drawing device at a speed of 300 m/min and controlling the elongation at 20-40% to obtain a drawn yard of 66dtex-112 filament; immersing the obtained sea-island composite fiber in a 1 wt % aqueous solution of sodium hydroxide at 80° C. so as to remove the sea component by dissolution.

[0203] The test data of the sea-island fibers obtained were shown in Table 1.

TABLE-US-00001 TABLE 1 Comparison of properties of the products in the Examples of the present invention and the Comparative Examples Example 1 Example 2 Example 3 Example 4 Example 5 Monofilament (dtex) 0.05 0.08 0.06 0.02 0.03 Break Strength (CN/dtex) 4.2 4.5 3.9 5.0 3.9 Elongation at Break (%) 45.2 48.1 38.9 35.2 33.4 Initial Modulus (CN/dtex) 38.4 35.7 38.3 33.8 40.2 K/S 18.5 19.2 22.4 20.5 18.9 Dye Uptake (%) 96.5 97.4 98.2 97.2 98.6 Dyeing Uniformity 4.5 4.5 4.5 4.0 4.0 (grey scale)/grade Soap Fastness fading 4.0 4.0 4.0 3.5 4.0 (grade) staining 4.0 3.5 3.5 4.0 4.0 Comparative Comparative Comparative Comparative Example 6 Example 1 Example 2 Example 3 Example 4 Monofilament(dtex) 0.05 0.05 0.05 0.05 0.05 Break Strength (CN/dtex) 4.0 3.9 3.8 4.1 3.2 Elongation at Break (%) 40.3 39.6 43.5 45.2 28.5 Initial Modulus (CN/dtex) 33.6 45.2 46.3 48.5 30.5 K/S 21.6 15.5 15.2 14.7 14.2 Dye Uptake (%) 97.5 88.5 87.6 85.4 85.5 Dyeing Uniformity 4.0 3.5 3.0 3.0 3.0 (grey scale)/grade Soap Fastness fading 3.5 2.5 2.5 2.5 2.5 (grade) staining 3.5 2.5 2.5 2.5 2.5

[0204] The polyamide sea-island fibers prepared in Examples 1 to 6 of the present invention had lower initial modulus as compared with those prepared in Comparative Examples 1 to 3. Therefore, the polyamide sea-island fibers prepared in Examples 1 to 6 had better softness. In addition, the polyamide sea-island fibers of the present invention had good dyeing properties. The polyamide sea-island fibers prepared in Examples 1 to 6 are also significantly better than those prepared in Comparative Examples 1 to 3 in terms of dye uptake, dyeing grey scale, dyeing depth and color fastness.

[0205] Therefore, the polyamide sea-island fiber monofilament prepared by the present invention is finer, and has soft and delicate hand feel. The bending rigidity is significantly reduced, the gloss is soft, the fiber specific surface area is larger, and the structure is of high-density. The polyamide sea-island fiber monofilament prepared by the present invention is more suitable for use in the field of imitation wools, imitation silks, imitation leathers, imitation peach skins, imitation suedes, high-density waterproof fabrics, high-performance cleaning clothes, high-performance adsorbing and filtering materials, highly oil absorptive materials, highly water absorptive materials, thermal insulation materials, medical materials, automotive trim materials, safety shoes, cases, handbags, sofas and the like.

[0206] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, but not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those ordinary skilled in the art should understand that the technical solutions described in the foregoing embodiments can be further modified, or can be equivalently replaced in terms of some or all of the technical features thereof. These modifications or replacements do not make the spirits of the corresponding technical solutions depart from the scope of technical solutions of the embodiments of the present invention.