Parallel composite elastic fiber and preparation method and application thereof

Abstract

The invention discloses a parallel composite elastic fiber and a preparation method and application thereof. The polyamide composite material has a first parallel structure and a second parallel structure, the first parallel structure is a polyamide 56 / 6 copolymer, the second parallel structure is polyamide 5X or polyamide 6X, and X is any natural number from 10 to 16. The parallel composite elastic fiber not only has excellent mechanical properties and excellent dimensional stability, but also has excellent curling performance and soft hand feeling, and can be used for developing elastic fabrics. The fabric is low in moisture regain, good in strength, good in elasticity and good in dimensional stability, can be used for close-fitting sportswear such as sports underwear, yoga clothes and riding clothes, and is more suitable for fabrics with high requirements for strength and wear resistance, such as ski suits, down jackets, outdoor jackets and other fabrics used under special weather conditions.

Description

Technical Field

[0001] The invention relates to a parallel composite elastic fiber and a preparation method and application thereof. Background Art

[0002] Parallel composite elastic fiber is obtained by melt spinning two polymers with good compatibility but large difference in thermal shrinkage according to a certain ratio. Since the two components have different thermal shrinkage properties after drawing and shaping, different shrinkage effects appear during the heat treatment process. Since the two components are relatively compatible, the component with a larger shrinkage rate will restrain the component with a smaller shrinkage rate during the heat treatment process, thus forming a three-dimensional curling structure.

[0003] In addition to the large difference in thermal shrinkage and good compatibility between the two raw materials, during the spinning process, the fluidity of the two components can be adjusted by adjusting the viscosity of the raw materials, temperature, moisture and other parameters to adjust the three-dimensional structure of the elastic fiber. This curled fiber has different degrees of elasticity and elasticity like a spring, and has a curling elasticity similar to wool. This three-dimensional spiral curl is different from the curling of conventional thermoplastic fibers obtained by mechanical means of physical pressure and heating. This curling belongs to "self-curling". Compared with mechanical processing curling, self-curling fibers have better elasticity and more durable and stable curling. At present, two-component parallel elastic fibers are mainly polyester. However, with the increasing demand for comfortable fabrics, the requirements for softness, comfort and excellent moisture absorption of fabrics are getting higher and higher. Therefore, compared with polyester, polyamide materials show better moisture absorption and wear resistance, so the development of polyamide fibers for elastic fabrics has a broader application prospect.

[0004] Chinese patent CN109957856B discloses a polyamide composite elastic fiber, which includes a first parallel structure and a second parallel structure, the first parallel structure is polyamide 5X, and the second parallel structure is polyester and / or polyamide 6X, but the tensile properties and curling properties of the composite elastic fiber need to be further improved.

[0005] Therefore, it is of great significance to develop a self-curling elastic fiber with better tensile and curling properties, good wear resistance and soft hand feel for elastic fabrics. Summary of the invention

[0006] The technical problem to be solved by the present invention is to overcome the defects of the prior art self-curling elastic fibers, such as low hygroscopicity, wear resistance, low strength, or the need to further improve the tensile properties and curling properties, and provide a parallel composite elastic fiber and its preparation method and application.

[0007] In order to achieve the above object, the present invention adopts the following technical solutions:

[0008] The present invention provides a parallel composite elastic fiber, which includes a first parallel structure and a second parallel structure, wherein the first parallel structure is a polyamide 56 / 6 copolymer, and the second parallel structure is a polyamide 5X or a polyamide 6X, wherein X is any natural number from 10 to 16;

[0009] The mass ratio of the first parallel structure to the second parallel structure is (35-65):(65-35).

[0010] In the present invention, the mass ratio of the first parallel structure and the second parallel structure is preferably (40-60):(60-40), and more preferably (45-55):(55-45).

[0011] In some specific embodiments, the mass ratio of the first parallel structure to the second parallel structure is 30:70, 35:65, 40:60, 45:65, 50:50, 55:45, 60:65 or 65:35.

[0012] In some specific embodiments, in the polyamide 56 / 6 copolymer, the mass of caprolactam accounts for 2-20% of the total mass of the synthetic raw materials, preferably 2.5-19%, and more preferably 3-18%, for example 3.5%, 4%, 5%, 6%, 7%, 8%, 9%, 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, or 17.5%.

[0013] In the present invention, those skilled in the art will understand that the polyamide 56 / 6 copolymer refers to a polymer obtained by copolymerizing synthetic raw materials including 1,5-pentanediamine, adipic acid and caprolactam.

[0014] Wherein, in the polyamide 56 / 6 copolymer, the molar ratio of 1,5-pentanediamine to adipic acid is preferably (1-1.08):1.

[0015] Wherein, the 1,5-pentanediamine and adipic acid are preferably prepared from bio-based raw materials by fermentation or enzyme conversion. The preparation of pentamethylenediamine and adipic acid by fermentation or enzyme conversion is beneficial to the sustainable development of the ecological environment.

[0016] The present invention adjusts the proportion of structural units in the polyamide 56 / 6 copolymer to make the polyamide 56 / 6 copolymer have a high shrinkage rate. The present invention uses the polyamide 56 / 6 copolymer with a high shrinkage rate as the first parallel structure and cooperates with the second structure with a low shrinkage rate to improve the curling performance, elastic recovery performance and elastic stability of the polyamide parallel composite elastic fiber.

[0017] In some specific embodiments, the melting point of the polyamide 56 / 6 copolymer is 180-260°C, such as 211°C, 240°C, 250°C or 252°C, preferably 190-250°C, and more preferably 200-240°C.

[0018] In some specific embodiments, the terminal amino group content of the polyamide 56 / 6 copolymer is 30-65 mmol / kg, such as 47.3 mmol / kg, 48 mmol / kg, 49.5 mmol / kg or 63 mmol / kg, preferably 40-60 mmol / kg, and more preferably 45-55 mmol / kg.

[0019] In some specific embodiments, the oligomer content in the polyamide 56 / 6 copolymer is less than 1.5 wt %, for example 0.4 wt %, 0.7 wt %, 1.1 wt % or 1.4 wt %.

[0020] In some specific embodiments, the water content of the polyamide 56 / 6 copolymer is 50-1300 ppm, preferably 200-1000 ppm, more preferably 300-800 ppm, and further more preferably 400-700 ppm, for example 410 ppm, 470 ppm, 480 ppm or 490 ppm.

[0021] In some specific embodiments, the relative viscosity of the polyamide 56 / 6 copolymer and 96 wt % sulfuric acid is 2.0-3.5, preferably 2.1-3.3, more preferably 2.3-3.0, such as 2.51, 2.63, 2.68 or 2.72.

[0022] Wherein, the synthetic raw materials of the polyamide 56 / 6 copolymer also include other comonomers and / or additives.

[0023] "Other comonomers" generally refer to monomers participating in the copolymerization in the synthetic raw materials of the polyamide 56 / 6 copolymer except pentamethylenediamine, adipic acid and caprolactam, preferably any one or more of aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, aromatic dicarboxylic acids, ethylenediamine, hexamethylenediamine, cyclohexanediamine, benzylenediamine, 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, p-aminomethylbenzoic acid, caprolactam and ω-laurolactam.

[0024] Preferably, the other comonomers account for 0.001-10% of the total mass of the synthetic raw materials of the polyamide 56 / 6 copolymer.

[0025] The additives preferably include any one or more of a matting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, a fluorescent brightener and an antistatic agent.

[0026] Preferably, the additive is added in an amount of 0.001-10% of the total mass of the synthetic raw materials of the polyamide 56 / 6 copolymer.

[0027] In some specific embodiments, the preparation method of the polyamide 56 / 6 copolymer comprises the following steps:

[0028] M1, the synthetic raw material of the polyamide 56 / 6 copolymer is mixed with water to form a mixed liquid;

[0029] M2. The mixed solution in step M1 is subjected to heating and pressure-increasing, exhausting, pressure-maintaining, pressure-reducing and vacuuming treatments in sequence to obtain a polyamide 56 / 6 copolymer.

[0030] Preferably, the heating and pressurizing pressure is 0.25-2.3 MPa.

[0031] Preferably, the pressure of the pressure maintenance is 1.6-2.3Mpa.

[0032] Preferably, the pressure maintaining temperature is 250-280°C.

[0033] Preferably, the pressure holding time is 1-5 hours.

[0034] Preferably, the temperature of the reaction system at the end of the pressure maintenance is 180-230°C.

[0035] Preferably, the pressure is reduced to a pressure of 0-0.35 MPa.

[0036] Preferably, the temperature of the reaction system is 200-250°C when the pressure reduction is completed.

[0037] Preferably, the vacuum is evacuated to a vacuum degree of -0.08 to -0.01 MPa.

[0038] Preferably, the temperature after vacuuming is 220-280°C.

[0039] Preferably, the mixed solution in step M1 also includes a fluorescent whitening agent.

[0040] Preferably, the fluorescent whitening agent accounts for 0.001-10% of the total mass of 1,5-pentanediamine, adipic acid and caprolactam, and more preferably 0.3wt%.

[0041] In some specific embodiments, the polyamide 5X is one or more of polyamide 510, polyamide 511, polyamide 512, polyamide 513, polyamide 514, polyamide 515 and polyamide 516.

[0042] In some specific embodiments, the polyamide 6X is one or more of polyamide 610, polyamide 611, polyamide 612, polyamide 613, polyamide 614, polyamide 615 and polyamide 616.

[0043] In some specific embodiments, the moisture content of the second parallel structure is 50-1300 ppm, preferably 200-1000 ppm, more preferably 300-800 ppm, and further more preferably 400-700 ppm, for example 400 ppm, 440 ppm, 442 ppm, 450 ppm, 460 ppm, 470 ppm or 500 ppm.

[0044] In some specific embodiments, the relative viscosity of the second parallel structure and 96 wt % sulfuric acid is 1.5-3.0, preferably 1.6-2.7, for example 1.64, 1.68, 1.82, 1.86, 2.30, 2.32, 2.42, 2.47, 2.52, 2.55, 2.56, 2.58 or 2.66.

[0045] In the present invention, the total amount of the first parallel structure and the second parallel structure may be 100 parts.

[0046] In some specific embodiments, the linear density of the parallel composite elastic fibers is 10-300 dtex, preferably 20-200 dtex, and more preferably 30-100 dtex.

[0047] In some specific embodiments, the number of single fibers contained in the parallel composite elastic fibers is 10-100f, such as 25-100f, such as 36f, 48f, 58f or 68f, preferably 35-60f.

[0048] In some specific embodiments, the linear density (dpf) of a single fiber in the parallel composite elastic fiber is less than 5, preferably 3, more preferably less than 2, such as 1.94, 1.46 or 1.03. The dpf number is generally obtained by dividing the linear density by the number of spinneret holes.

[0049] In some specific embodiments, the breaking strength of the parallel composite elastic fiber is 2.0-7.0 cN / dtex, preferably 3.5-6 cN / dtex, and more preferably 4-4.8 cN / dtex.

[0050] In some specific embodiments, the elongation at break of the parallel composite elastic fibers is 20-100%, preferably 35-70%, and more preferably 41-50%.

[0051] In some specific embodiments, the boiling water shrinkage of the parallel composite elastic fiber is 2-50%, preferably 5-30%, and more preferably 9-15%.

[0052] In some specific embodiments, the curl shrinkage rate of the parallel composite elastic fibers is 30-90%, preferably 50-80%, and more preferably 68-77%.

[0053] In some specific embodiments, the curl modulus of the parallel composite elastic fiber is 20-60%, preferably 30-50%, and more preferably 38-44%.

[0054] In some specific embodiments, the curl stability of the parallel composite elastic fibers is ≥90%, preferably ≥91%, and more preferably ≥92%.

[0055] In some specific embodiments, the curling elongation of the parallel composite elastic fibers is ≥150%, preferably ≥300%, and more preferably ≥400%.

[0056] The present invention also provides a method for preparing a parallel composite elastic fiber, which comprises the following steps:

[0057] S1 the first parallel structure material and the second parallel structure material are melted and then converged for spinning to obtain parallel composite primary fibers;

[0058] The parallel composite primary fibers described in S2 are pre-treated and drawn to obtain parallel composite elastic fibers.

[0059] In S1, the melting is generally performed in a screw extruder.

[0060] The material of the first parallel structure is generally melted in the first screw extruder, and the first screw extruder preferably includes the following five temperature zones:

[0061] The temperature of zone 1 is 180-240°C, for example, 200°C, 220°C or 225°C;

[0062] The temperature of the second zone is 200-250°C, for example 210°C, 240°C or 245°C;

[0063] The temperature of the third zone is 210-260°C, for example 225°C, 260°C or 265°C;

[0064] The temperature of the fourth zone is 220-270°C, for example, 245°C, 270°C or 273°C;

[0065] The temperature of zone five is 230-280°C, for example 255°C, 270°C or 273°C.

[0066] The material of the second parallel structure is generally melted in the second screw extruder, and the second screw extruder preferably includes the following five temperature zones:

[0067] The temperature of zone 1 is 180-260°C, for example, 190°C, 195°C, 200°C, 202°C, 205°C, 210°C, 215°C or 235°C;

[0068] The temperature of the second zone is 200-270°C, for example, 205°C, 208°C, 210°C, 215°C, 220°C, 225°C, 230°C, 245°C or 250°C;

[0069] The temperature of the third zone is 210-280°C, for example, 218°C, 230°C, 240°C, 250°C or 260°C;

[0070] The temperature of the fourth zone is 230-290°C, for example 245°C, 255°C or 260°C;

[0071] The temperature of zone five is 240-290°C, for example, 245°C, 250°C, 252°C, 255°C, 260°C or 265°C.

[0072] In S1, the convergent spinning process is generally that the melts are transported to the composite spinning box through melt pipes respectively, enter the assembly, and then pass through the diversion of the composite spinneret, and are bonded together at the composite spinneret to obtain the parallel composite primary fibers.

[0073] The composite spinneret is generally a circular spinneret or an 8-shaped spinneret, preferably an 8-shaped spinneret. Preferably, the 8-shaped spinneret is provided with a plurality of spinneret holes, and the spinneret holes include two parallel circular ones.

[0074] The distance D between the centers of the two parallel circles may be 0.28-0.6 mm, preferably 0.3-0.55 mm, more preferably 0.32-0.45 mm, such as 0.36 mm, 0.38 mm, 0.4 mm or 0.42 mm.

[0075] The radius r of the two parallel circles may be 0.1-0.3 mm, preferably 0.12-0.28 mm, such as 0.14 mm or 0.18 mm.

[0076] The spinneret hole D-2r may be 0.03-0.14 mm, such as 0.06, 0.08 or 0.10 mm, preferably 0.08-0.12 mm.

[0077] The radius r of the circular spinneret may be 0.1-0.3 mm, preferably 0.12-0.28 mm, such as 0.14 mm or 0.18 mm.

[0078] The number of holes of the composite spinneret may be 10-100f, such as 25-100f, such as 36f, 48f, 58f or 68f, preferably 35-60f.

[0079] In some specific embodiments, the composite spinneret may be ○-shaped, with a hole number of 48f and a radius r of 0.14 mm.

[0080] In S1, preferably, the two melts before the convergent spinning are metered by a metering pump. The metering pump is generally a component for metering the melt during the melt spinning process.

[0081] In some specific embodiments, in S1, the pressure of the spinning assembly during the convergent spinning process is 10-28 MPa, preferably 13-25 MPa, more preferably 15-20 MPa, for example 12 MPa, 13 MPa, 14 MPa, 15 MPa, 16 MPa or 17 MPa.

[0082] In some specific embodiments, in S1, the temperature of the spinning beam during the convergent spinning process is 240-280°C, such as 260°C, 270°C, 273°C or 280°C.

[0083] In S2, the pre-treatment generally includes side-blowing cooling, oiling and pre-networking.

[0084] In some specific embodiments, the wind speed of the side-blown air cooling is 0.3-0.8 m / s, preferably 0.4-0.7 m / s, such as 0.55 m / s, 0.6 m / s, 0.65 m / s or 0.7 m / s.

[0085] In some specific embodiments, the wind temperature of the side-blown air cooling is 15-27°C, preferably 18-26°C, such as 22°C, 24°C, 25°C or 26°C.

[0086] In some specific embodiments, the humidity of the cross-blown air is 60-90%, preferably 68-85%, such as 64%, 65%, 67%, 68% or 75%.

[0087] The oiling method can be conventional in the art, preferably oiling with an oil nozzle.

[0088] In S2, the drawing is generally performed in a two-step method or a one-step method, preferably a one-step method.

[0089] The two-step method generally involves first obtaining a pre-drawn yarn (POY), and then obtaining a drawn textured yarn DTY through false twisting, drawing and winding.

[0090] The preparation method of the pre-drawn POY yarn generally adopts winding forming by a winding machine.

[0091] In some specific embodiments, the winding speed of the winder is 3000-5000 m / min, preferably 3500-4500 m / min, such as 4100 m / min or 4300 m / min.

[0092] In some specific embodiments, in the DTY process, the false twisting temperature is 120-190°C, preferably 140-180°C, such as 130°C, 135°C or 150°C.

[0093] In some specific embodiments, in the DTY process, the stretching ratio of the stretching is 1.0-2.5, preferably 1.2-2.0, such as 1.28, 1.3, 1.32, 1.38 or 1.4.

[0094] In some specific embodiments, in the DTY process, the winding speed is 300-1000 m / min, preferably 500-700 m / min, such as 500 m / min, 550 m / min or 600 m / min.

[0095] The one-step method generally refers to the resin being melt extruded, cooled, oiled, pre-networked, and then directly subjected to hot roller drawing, main network, and winding to obtain fully drawn yarn FDY of parallel composite elastic fibers.

[0096] The hot roller drawing in the FDY process is preferably three pairs of hot rollers, namely HGR1, HGR2 and HGR3 (HGR is the Chinese name of heating drawing roller, which is the abbreviation of Heating godet roller).

[0097] The temperature of the HGR1 can be conventional in the art.

[0098] In some embodiments, the temperature of HGR1 is 10-120°C, preferably 20-100°C, such as 75°C, 80°C, 85°C, 90°C or 95°C.

[0099] The temperature of the HGR2 can be conventional in the art.

[0100] In some specific embodiments, the temperature of HGR2 is 120-180°C, preferably 140-160°C, such as 135°C, 140°C, 145°C, 150°C or 160°C.

[0101] The temperature of the HGR3 can be conventional in the art.

[0102] In some embodiments, the temperature of HGR3 is 10-120°C, preferably 20-100°C, such as 75°C, 80°C or 90°C.

[0103] In some specific embodiments, the draft ratio in the FDY process is 2.0-5.0, preferably 2.5-4.5, such as 3.2, 3.65, 3.7, 3.75, 3.8, 3.9 or 4.0.

[0104] The winding method in the FDY process can be conventional in the art, generally by winding by a winder.

[0105] In some specific embodiments, the winding speed of the winder is 2800-5500 m / min, preferably 3300-4800 m / min, for example 4200 m / min, 4300 m / min, 4400 m / min, 4500 m / min or 4600 m / min.

[0106] The present invention also provides an application of the above-mentioned parallel composite elastic fiber in fabrics.

[0107] In the present invention, the fabric can be not only close-fitting sportswear such as sports bras, yoga clothes, and cycling clothes, but also fabrics with high requirements for strength and wear resistance, such as ski suits, down jackets, and jackets used in special climatic conditions.

[0108] On the basis of being in accordance with the common sense in the art, the above-mentioned preferred conditions can be arbitrarily combined to obtain the preferred embodiments of the present invention.

[0109] The reagents and raw materials used in the present invention are commercially available.

[0110] The positive and progressive effects of the present invention are:

[0111] The present invention adopts a polyamide 56 / 6 copolymer with a high shrinkage rate as the first parallel structure, and matches it with a second parallel structure with a low shrinkage rate. The prepared parallel composite elastic fiber not only has excellent mechanical properties (such as high fiber strength) and excellent dimensional stability (such as low boiling water shrinkage), but also has excellent curling properties (such as curling elongation) and soft hand feel (such as low modulus), and can be used to develop elastic fabrics.

[0112] The parallel composite elastic fiber of the present invention has a low moisture regain, good strength and elasticity, and good dimensional stability. In addition to being used in close-fitting sportswear such as sports bras, yoga clothes, and cycling clothes, it is more suitable for fabrics with high requirements for strength and wear resistance, such as ski suits, down jackets, and jackets used in special climatic conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0113] Figure 1 It is a structural diagram of the 8-shaped spinneret of Examples 1-19 and 21 of the present invention.

[0114] Figure 2 This is a microscope image of the cross section of the parallel composite elastic fiber prepared in Example 1 (magnified 80 times).

[0115] Figure 3 This is a microscope image of the cross section of the parallel composite elastic fiber prepared in Example 20 (magnified 80 times). DETAILED DESCRIPTION

[0116] The present invention is further described below by way of examples, but the present invention is not limited to the scope of the examples. The experimental methods in the following examples without specifying specific conditions are carried out according to conventional methods and conditions, or selected according to the product specifications.

[0117] The detection method of the performance parameters involved in the present invention is as follows:

[0118] 1) Relative viscosity:

[0119] By the Ubbelohde viscometer concentrated sulfuric acid method: accurately weigh 0.25±0.0002 g of the dried polyamide 56 chips or their staple fiber samples, add 50 mL of concentrated sulfuric acid (96 wt %) to dissolve, and measure and record the concentrated sulfuric acid flow time t0 and the polyamide sample solution flow time t in a constant temperature water bath at 25°C.

[0120] Viscosity number calculation formula:

[0121] Relative viscosity = t / t0;

[0122] t—solution flow time;

[0123] t0—Solvent flow time.

[0124] 2) Linear density:

[0125] The test method of linear density can refer to GB / T 14343-2008 Test method for linear density of chemical fiber filaments; use YG086 yarn length measuring instrument, the circumference of the yarn frame is (1.000±0.002)m. Collect the length and mass of each sample respectively, the length is obtained by multiplying the length of the yarn frame by the number of turns, the sample is weighed after debugging in standard atmosphere, accurate to 1mg, each sample is tested 10 times, and the average value is calculated.

[0126] 3) Breaking strength, elongation at break, modulus:

[0127] The determination of breaking strength and breaking elongation can refer to GB / T 14344-2008 Test method for tensile properties of chemical fibers; apply 0.05±0.005cN / dtex pre-tension, holding distance 500mm, stretching speed 500mm / min, modulus = breaking strength corresponding to 1% elongation at break × 100.

[0128] 4) Moisture regain:

[0129] The determination method is: put the washed fiber into the oven to dry in a loose state, and then place the dried fiber sample in the standard atmosphere specified in GB / T6529 for adjustment and balance, and adjust the humidity for 2 hours. The sample after washing and humidity adjustment is subjected to moisture regain determination, and the moisture regain determination method is implemented in accordance with GB / T6503, where the drying temperature of the oven is 105°C and the drying time is 1 hour.

[0130] 5) Boiling water shrinkage

[0131] The boiling water shrinkage rate refers to GB / T6505-2017 "Test method for thermal shrinkage of chemical fiber filaments (after treatment)".

[0132] S = ((L0-L1) / L0) × 100%;

[0133] S: thermal shrinkage (boiling water shrinkage);

[0134] L0: length of the sample before heat treatment, in millimeters (mm);

[0135] L1: The length of the sample after heat treatment, in millimeters (mm).

[0136] 6) Curling performance

[0137] According to GB / T6506-2017 "Test method for shrinkage performance of synthetic fiber textured yarn".

[0138] Curl shrinkage = ((L1-L2) / L1) × 100%;

[0139] Crimp modulus = ((L1-L3) / L1) × 100%;

[0140] Curl stability = ((L4-L1) / (L1-L2)) × 100%;

[0141] L1: The fiber length is measured after the fiber is subjected to a tension of 0.2 cN / dtex for 10 seconds;

[0142] L2: The fiber length measured after the fiber is subjected to a tension of 0.001 cN / dtex for 10 min;

[0143] L3: The fiber length is measured after the fiber is subjected to a tension of 0.01 cN / dtex for 10 seconds;

[0144] L4: The fiber length is measured after the fiber is subjected to a tension of 1.0 cN / dtex for 10 seconds.

[0145] 7) Curl elongation

[0146] Curl elongation: The percentage ratio of the deformation length of the curled textured yarn from the natural state to the complete elimination of the curled structure under the action of tensile force to the fiber length in the natural state.

[0147] Curl elongation = (L1-L0) / L0×100%

[0148] L0: the length of the crimped textured yarn in its natural state;

[0149] L1: The length of the curled textured yarn when it is slowly stretched to a straight state under the action of tensile force (tension is 0.2 cN / dtex).

[0150] 8) Hand feel evaluation:

[0151] The subjective evaluation group evaluation method is adopted. The evaluation group consists of 24 people. They evaluate the softness and smoothness of each group of experimental samples. The evaluation group members rank the order by touching. Then the average result is calculated by statistical method. The hand feel is divided into four levels, level 1 is the worst - hard, level 2 is the second - harder, level 3 is better - softer, and level 4 is the best - soft.

[0152] The sources of raw materials involved in the present invention are as follows:

[0153] 1) Preparation method of polyamide 56 / 6 copolymer:

[0154] The preparation method of the polyamide 56 / 6 copolymer used in the embodiment and the comparative example comprises the following steps: under nitrogen conditions, 1,5-pentanediamine, adipic acid, caprolactam and water are uniformly mixed, and a fluorescent whitening agent is added at the same time; wherein, by adjusting the mass proportion of caprolactam, copolymers with different mass ratios are prepared, 1,5-pentanediamine, adipic acid, caprolactam are added, and the molar ratio of 1,5-pentanediamine and adipic acid is (1-1.08):1; in addition, the fluorescent whitening agent accounts for 1,5-pentanediamine, adipic acid and caprolactam. The solution is heated to raise the pressure in the reaction system to 0.25-2.3 MPa, exhaust, maintain the pressure, and then reduce the pressure to reduce the pressure in the reaction system to 0-0.35 MPa, and evacuate to a vacuum degree of -0.08 to -0.01 MPa to obtain a polyamide melt; during the reaction process, the temperature of the reaction system is 180-230°C when the pressure is maintained, the temperature of the reaction system is 200-250°C after the pressure reduction, and the temperature after evacuation is 220-280°C.

[0155] 2) Raw materials: polyamide 510, polyamide 511, polyamide 512, polyamide 513, polyamide 514, polyamide 515, polyamide 516, polyamide 610, polyamide 611, polyamide 612, polyamide 613, polyamide 614, polyamide 615, polyamide 616 were all purchased from Cathay (Jinxiang) Biomaterials Co., Ltd.

[0156] 3) Polyethylene terephthalate was purchased from Sinopec; trimethylene terephthalate was purchased from DuPont; polyamide 56 was purchased from Cathay (Jinxiang) Biomaterials Co., Ltd.; polyamide 6 was purchased from Remiful.

[0157] Example 1

[0158] 1) A polyamide 56 / 6 copolymer (5% by mass of caprolactam, melting point 250°C, terminal amino group 48mmol / kg, oligomer 0.7wt%, water content 470ppm, relative viscosity with 96wt% sulfuric acid 2.63) melt and a polyamide 510 melt are respectively transported to a composite spinning manifold through melt pipes, enter the assembly, and then pass through the diversion of the composite spinneret and are bonded together at the spinneret to form primary yarn.

[0159] The ratio of the two materials is controlled by adjusting the frequency of the metering pump. The content of the first material, polyamide 56 / 6 copolymer, is 50wt%, and the content of the second material, polyamide 510, is 50wt%.

[0160] Among them, the heating temperature settings of the five zones of the screw extruder corresponding to polyamide 56 / 6 are as follows: the temperature of zone 1 is 220°C, the temperature of zone 2 is 240°C, the temperature of zone 3 is 260°C, the temperature of zone 4 is 270°C, and the temperature of zone 5 is 270°C; the heating temperature settings of the five zones of the screw extruder corresponding to polyamide 510 are as follows: the temperature of zone 1 is 200°C, the temperature of zone 2 is 215°C, the temperature of zone 3 is 230°C, the temperature of zone 4 is 245°C, and the temperature of zone 5 is 250°C.

[0161] The melt passes through the metering pump and the spinneret (8-shaped, 8-shaped spinneret structure as shown in the figure) in the spinning box. Figure 1 As shown, the number of holes is 48f, D, r, and D-2r are 0.36mm, 0.14mm, and 0.08mm respectively) for extrusion, the temperature of the spinning manifold is 270°C, and the spinning assembly pressure of the spinning manifold is 16MPa.

[0162] 2) The raw silk is subjected to side-blowing cooling, oiling with an oil nozzle, pre-internetting, and then drafted by three pairs of hot rollers, main internetting, and finally wound by a winder to obtain parallel composite elastic fibers.

[0163] Cooling is carried out by side blowing, with a wind speed of 0.7m / s, a wind temperature of 25°C, and a humidity of 68%; the stretching process uses three pairs of hot rollers, the total stretching multiple is 3.8, the temperature of HGR1 is 90°C, the temperature of HGR2 is 150°C, the temperature of HGR3 is 90°C, and the winding speed is 4500m / min.

[0164] The obtained microscopic image of the cross section of the parallel composite elastic fiber (magnified 50 times) is as follows Figure 2 shown.

[0165] The key parameters in Examples 1-19 are shown in Table 1.

[0166] Table 1

[0167]

[0168]

[0169] Example 2

[0170] Polyamide 511 is the second material, and the corresponding five-zone heating temperature of the screw extruder is set as follows: zone 1 temperature is 200° C., zone 2 temperature is 215° C., zone 3 temperature is 225° C., zone 4 temperature is 240° C., and zone 5 temperature is 245° C. Other spinning conditions are the same as those in Example 1.

[0171] Example 3

[0172] Polyamide 512 is the second material, and the corresponding five-zone heating temperatures of the screw extruder are set as follows: the temperature of zone 1 is 202°C, the temperature of zone 2 is 215°C, the temperature of zone 3 is 230°C, the temperature of zone 4 is 250°C, and the temperature of zone 5 is 260°C. Other spinning conditions are consistent with those in Example 1.

[0173] Example 4

[0174] Polyamide 513 is the second material, and the corresponding five-zone heating temperature settings of the screw extruder are as follows: the temperature of zone 1 is 195°C, the temperature of zone 2 is 210°C, the temperature of zone 3 is 230°C, the temperature of zone 4 is 245°C, and the temperature of zone 5 is 255°C. Other spinning conditions are consistent with Example 1.

[0175] Example 5

[0176] Polyamide 514 is the second material, and the corresponding five-zone heating temperatures of the screw extruder are set as follows: the temperature of zone 1 is 190°C, the temperature of zone 2 is 210°C, the temperature of zone 3 is 230°C, the temperature of zone 4 is 245°C, and the temperature of zone 5 is 260°C. Other spinning conditions are consistent with Example 1.

[0177] Example 6

[0178] Polyamide 515 is the second material, and the corresponding five-zone heating temperature settings of the screw extruder are as follows: the temperature of zone 1 is 180°C, the temperature of zone 2 is 200°C, the temperature of zone 3 is 218°C, the temperature of zone 4 is 230°C, and the temperature of zone 5 is 250°C. Other spinning conditions are consistent with Example 1.

[0179] Example 7

[0180] Polyamide 516 is the second material, and the corresponding five-zone heating temperature settings of the screw extruder are as follows: the temperature of zone 1 is 180°C, the temperature of zone 2 is 208°C, the temperature of zone 3 is 220°C, the temperature of zone 4 is 230°C, and the temperature of zone 5 is 255°C. Other spinning conditions are consistent with Example 1.

[0181] Example 8

[0182] Polyamide 610 is the second material, and the corresponding five-zone heating temperatures of the screw extruder are set as follows: zone 1 temperature is 235°C, zone 2 temperature is 245°C, zone 3 temperature is 250°C, zone 4 temperature is 260°C, zone 5 temperature is 260°C, and other spinning conditions are consistent with Example 1.

[0183] Example 9

[0184] Polyamide 611 melt is the second material, and the corresponding five-zone heating temperatures of the screw extruder are set as follows: zone 1 temperature is 210°C, zone 2 temperature is 230°C, zone 3 temperature is 250°C, zone 4 temperature is 260°C, zone 5 temperature is 265°C, and other spinning conditions are consistent with Example 1.

[0185] Example 10

[0186] Polyamide 612 is the second material, and the corresponding five-zone heating temperatures of the screw extruder are set as follows: the temperature of zone 1 is 210°C, the temperature of zone 2 is 230°C, the temperature of zone 3 is 250°C, the temperature of zone 4 is 260°C, and the temperature of zone 5 is 260°C. Other spinning conditions are consistent with those in Example 1.

[0187] Embodiment 11

[0188] Polyamide 613 is the second material, and the corresponding five-zone heating temperature settings of the screw extruder are as follows: the temperature of zone 1 is 200°C, the temperature of zone 2 is 220°C, the temperature of zone 3 is 230°C, the temperature of zone 4 is 245°C, and the temperature of zone 5 is 260°C. Other spinning conditions are consistent with Example 1.

[0189] Example 12

[0190] Polyamide 614 is the second material, and the corresponding five-zone heating temperatures of the screw extruder are set as follows: the temperature of zone 1 is 205°C, the temperature of zone 2 is 225°C, the temperature of zone 3 is 238°C, the temperature of zone 4 is 253°C, and the temperature of zone 5 is 260°C. Other spinning conditions are consistent with Example 1.

[0191] Embodiment 13

[0192] Polyamide 615 is the second material, and the corresponding five-zone heating temperatures of the screw extruder are set as follows: the temperature of zone 1 is 195°C, the temperature of zone 2 is 205°C, the temperature of zone 3 is 220°C, the temperature of zone 4 is 235°C, and the temperature of zone 5 is 250°C. Other spinning conditions are consistent with Example 1.

[0193] Embodiment 14

[0194] Polyamide 616 is the second material, and the corresponding five-zone heating temperatures of the screw extruder are set as follows: the temperature of zone 1 is 190°C, the temperature of zone 2 is 205°C, the temperature of zone 3 is 220°C, the temperature of zone 4 is 240°C, and the temperature of zone 5 is 252°C. Other spinning conditions are consistent with Example 1.

[0195] Embodiment 15

[0196] Polyamide 56 / 6 copolymer (mass percentage of caprolactam is 3%, melting point is 252°C, terminal amino group is 63 mmol / kg, oligomer is 0.4wt%, water content is 410ppm, and relative viscosity with 96wt% sulfuric acid is 2.51) is used as the first material, and the corresponding five-zone heating temperatures of the screw extruder are set as follows: the temperature of zone 1 is 225°C, the temperature of zone 2 is 245°C, the temperature of zone 3 is 265°C, the temperature of zone 4 is 273°C, and the temperature of zone 5 is 273°C. Other spinning conditions are consistent with those in Example 1.

[0197] Example 16

[0198] Polyamide 56 / 6 copolymer (mass percentage of caprolactam is 9%, melting point is 240°C, terminal amino group is 49.5 mmol / kg, oligomer is 1.1wt%, water content is 480ppm, and relative viscosity with 96wt% sulfuric acid is 2.68) is used as the first material, and the corresponding five-zone heating temperatures of the screw extruder are set as follows: the temperature of zone 1 is 220°C, the temperature of zone 2 is 240°C, the temperature of zone 3 is 260°C, the temperature of zone 4 is 270°C, and the temperature of zone 5 is 270°C. Other spinning conditions are consistent with those in Example 1.

[0199] Embodiment 17

[0200] 1) A polyamide 56 / 6 copolymer (mass percentage of caprolactam is 20%, melting point is 221°C, terminal amino group is 48 mmol / kg, oligomer is 0.7wt%, water content is 500ppm, and relative viscosity with 96wt% sulfuric acid is 2.8) melt and a polyamide 510 melt are respectively transported to a composite spinning manifold through melt pipes, and after entering the assembly, they are diverted by a composite spinneret and bonded together at the spinneret to form primary yarns.

[0201] The ratio of the two materials is controlled by adjusting the frequency of the metering pump. The content of the first material, polyamide 56 / 6 copolymer, is 45wt%, and the content of the second material, polyamide 510, is 55wt%.

[0202] Among them, the heating temperature settings of the five zones of the screw extruder corresponding to polyamide 56 / 6 are as follows: the temperature of zone 1 is 200°C, the temperature of zone 2 is 210°C, the temperature of zone 3 is 225°C, the temperature of zone 4 is 245°C, and the temperature of zone 5 is 255°C; the heating temperature settings of the five zones of the screw extruder corresponding to polyamide 510 are as follows: the temperature of zone 1 is 200°C, the temperature of zone 2 is 215°C, the temperature of zone 3 is 230°C, the temperature of zone 4 is 245°C, and the temperature of zone 5 is 250°C.

[0203] The melt is extruded through a metering pump and a spinneret (8-shaped, number of holes 48f, D, r, D-2r are 0.36mm, 0.14mm, 0.08mm respectively) in a spinning manifold. The temperature of the spinning manifold is 260°C, and the spinning assembly pressure of the spinning manifold is 12MPa.

[0204] 2) The raw silk is subjected to side-blowing cooling, oiling with an oil nozzle, pre-interlacing, drawing by three pairs of hot rollers, main interlacing, and finally winding by a winder to obtain parallel composite elastic fibers.

[0205] Cooling is carried out by side blowing, with a wind speed of 0.7m / s, a wind temperature of 25°C, and a humidity of 65%; the stretching process uses three pairs of hot rollers, the total stretching multiple is 3.6, the temperature of HGR1 is 75°C, the temperature of HGR2 is 135°C, the temperature of HGR3 is 75°C, and the winding speed is 4200m / min.

[0206] Embodiment 18

[0207] The number of spinneret holes is 68f, and the rest is the same as in Example 1.

[0208] Embodiment 19

[0209] The spinnerets D, r, and D-2r are 0.38 mm, 0.14 mm, and 0.1 mm respectively, and the rest are the same as in Example 1.

[0210] Embodiment 20

[0211] The spinneret (○ type, number of holes 48f, r is 0.14mm), other conditions are the same as in Example 1, and the microscopic image (magnified 50 times) of the cross section of the obtained parallel composite elastic fiber is as follows Figure 3 shown.

[0212] Embodiment 21

[0213] Spinneret (8-shaped, number of holes 12f, D, r, D-2r are 0.36mm, 0.14mm, 0.08mm respectively), other conditions are the same as in Example 1.

[0214] Embodiment 22

[0215] Spinneret (8-shaped, number of holes 48f, D, r, D-2r are 0.42mm, 0.14mm, 0.14mm respectively, other conditions are the same as in Example 1.

[0216] Comparative Example 1

[0217] 1) Polyethylene terephthalate (PET) and polytrimethylene terephthalate (PTT) are melted separately and transported to the composite spinning manifold through a melt pipe. After entering the assembly, they are diverted by the composite spinneret and bonded together at the spinneret to form primary yarn.

[0218] The ratio of the two materials is controlled by adjusting the frequency of the metering pump, the PET content of the first material is 50wt%, and the PTT content of the second material is 50wt%.

[0219] Among them, the heating temperature settings of the five zones of the screw extruder corresponding to PET are as follows: the temperature of zone 1 is 250°C, the temperature of zone 2 is 265°C, the temperature of zone 3 is 275°C, the temperature of zone 4 is 280°C, and the temperature of zone 5 is 280°C; the heating temperature settings of the five zones of the screw extruder corresponding to PTT are as follows: the temperature of zone 1 is 250°C, the temperature of zone 2 is 265°C, the temperature of zone 3 is 275°C, the temperature of zone 4 is 280°C, and the temperature of zone 5 is 280°C.

[0220] The melt was extruded through a spinneret (8-shaped, number of holes 48f, D, r, D-2r 0.36mm, 0.14mm, 0.08mm respectively) of a spinning manifold. The temperature of the spinning manifold was 280°C, and the spinning assembly pressure of the spinning manifold was 17MPa.

[0221] 2) The raw silk is subjected to side-blowing cooling, oiling with an oil nozzle, pre-interlacing, drawing by three pairs of hot rollers, main interlacing, and finally winding by a winder to obtain parallel composite elastic fibers.

[0222] Cooling is carried out by side blowing, with a wind speed of 0.7m / s, a wind temperature of 25°C, and a humidity of 62%; the stretching process uses three pairs of hot rollers, the total stretching multiple is 3.5, the temperature of HGR1 is 75°C, the temperature of HGR2 is 140°C, the temperature of HGR3 is 90°C, and the winding speed is 4300m / min.

[0223] Comparative Example 2

[0224] 1) A polyamide 56 / 6 copolymer (the mass percentage of caprolactam is 20%, the melting point is 221°C, the terminal amino group is 48 mmol / kg, the oligomer is 0.7wt%, the water content is 500ppm, and the relative viscosity with 96wt% sulfuric acid is 2.8) melt and a polyamide 6 melt are respectively transported to a composite spinning manifold through melt pipes, and after entering the assembly, they are diverted by a composite spinneret and bonded together at the spinneret to form nascent fibers.

[0225] The ratio of the two materials is controlled by adjusting the frequency of the metering pump. The first material, polyamide 56 / 6 copolymer, has a content of 50 wt%, and the second material, polyamide 6 has a content of 50 wt%.

[0226] Among them, the heating temperature settings of the five zones of the screw extruder corresponding to the polyamide 56 / 6 copolymer are as follows: the temperature of zone 1 is 200°C, the temperature of zone 2 is 210°C, the temperature of zone 3 is 225°C, the temperature of zone 4 is 245°C, and the temperature of zone 5 is 255°C. The heating temperature settings of the five zones of the screw extruder corresponding to polyamide 6 are as follows: the temperature of zone 1 is 245°C, the temperature of zone 2 is 258°C, the temperature of zone 3 is 270°C, the temperature of zone 4 is 275°C, and the temperature of zone 5 is 270°C; the relative viscosity of polyamide 6 resin with 96wt% sulfuric acid is 2.6, and the water content is 800ppm.

[0227] The melt was extruded through a spinneret (8-shaped, number of holes 48f, D, r, D-2r 0.36mm, 0.14mm, 0.08mm respectively) of a spinning manifold. The temperature of the spinning manifold was 270°C, and the pressure of the spinning assembly of the spinning manifold was 14MPa.

[0228] 2) The raw silk is subjected to side-blowing cooling, oiling by an oil nozzle, pre-interlacing, drawing by three pairs of hot rollers, main interlacing, and finally winding by a winder to obtain a polyamide parallel composite elastic fiber;

[0229] Cooling is carried out by side blowing, with a wind speed of 0.8 m / s, a wind temperature of 25°C, and a humidity of 68%; the stretching process uses three pairs of hot rollers, the total stretching multiple is 3.2, the temperature of HGR1 is 80°C, the temperature of HGR2 is 140°C, the temperature of HGR3 is 80°C, and the winding speed is 4400 m / min.

[0230] Effect Example

[0231] The performance indicators of the parallel composite fibers prepared in Examples 1-22 and Comparative Examples 1-2 were tested in strict accordance with national standards and industry standards. When testing the fiber curling performance, the obtained fibers were treated in 100°C water for 30 minutes and dried before testing. The fiber mechanical performance indicators obtained by the test are shown in Table 2. The curling performance and boiling water shrinkage of the obtained parallel composite fibers were tested, and the results are shown in Table 3; as can be seen from Table 3, the curling performance of the polyamide parallel composite fibers prepared in Examples 1-22 is better than that of Comparative Examples 1-2 as a whole.

[0232] Table 2 Mechanical properties of fibers in Examples 1-22 and Comparative Examples 1-2

[0233]

[0234]

[0235] Table 3 Curl and elastic properties of fibers in Examples 1-22 and Comparative Examples 1-2

[0236]

[0237]

Claims

1. A parallel composite elastic fiber, characterized in that: It includes a first parallel structure and a second parallel structure, wherein the first parallel structure is a polyamide 56 / 6 copolymer, and the second parallel structure is a polyamide 5X or a polyamide 6X, wherein X is any natural number from 10 to 16; The mass ratio of the first parallel structure to the second parallel structure is (35-65):(65-35).

2. The parallel composite elastic fiber according to claim 1, characterized in that: The parallel composite elastic fibers meet one or more of the following conditions: (1) The linear density of the parallel composite elastic fiber is 10-300 dtex; (2) The number of single fibers contained in the parallel composite elastic fibers is 10-100f; (3) The linear density dpf of a single fiber in the parallel composite elastic fiber is less than 5; (4) The breaking strength of the parallel composite elastic fiber is 2.0-7.0 cN / dtex; (5) The elongation at break of the parallel composite elastic fiber is 20-100%; (6) The boiling water shrinkage of the parallel composite elastic fiber is 2-50%; (7) The curl shrinkage rate of the parallel composite elastic fiber is 30-90%; (8) The crimp modulus of the parallel composite elastic fiber is 20-60%; (9) the curl stability of the parallel composite elastic fibers is ≥ 90%; and, (10) The curling elongation of the parallel composite elastic fiber is ≥150%.

3. The parallel composite elastic fiber according to claim 2, characterized in that: The parallel composite elastic fibers meet one or more of the following conditions: (1) The linear density of the parallel composite elastic fiber is 20-200 dtex, preferably 30-100 dtex; (2) The number of single fibers contained in the parallel composite elastic fibers is 25-100f, preferably 35-60f; (3) The linear density dpf of a single fiber in the parallel composite elastic fiber is 3, preferably <2; (4) The breaking strength of the parallel composite elastic fiber is 3.5-6 cN / dtex, preferably 4-4.8 cN / dtex; (5) The elongation at break of the parallel composite elastic fiber is 35-70%, preferably 41-50%; (6) The boiling water shrinkage of the parallel composite elastic fiber is 5-30%, preferably 9-15%; (7) The curl shrinkage rate of the parallel composite elastic fiber is 50-80%, preferably 68-77%; (8) The crimp modulus of the parallel composite elastic fiber is 30-50%, preferably 38-44%; (9) The curl stability of the parallel composite elastic fiber is ≥ 91%, preferably ≥ 92%; and, (10) The curling elongation of the parallel composite elastic fiber is ≥300%, preferably ≥400%.

4. The parallel composite elastic fiber according to claim 1, characterized in that: The parallel composite elastic fibers meet one or more of the following conditions: (1) The mass ratio of the first parallel structure to the second parallel structure is (40-60): (60-40), preferably (45-55): (55-45); (2) In the polyamide 56 / 6 copolymer, the mass of caprolactam accounts for 2-20% of the total mass of the synthetic raw materials, preferably 2.5-19%, more preferably 3-18%; and, (3) The synthetic raw materials of the polyamide 56 / 6 copolymer further include other comonomers and / or additives participating in the copolymerization in addition to pentamethylenediamine, adipic acid and caprolactam; The other comonomers are preferably any one or more of aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, aromatic dicarboxylic acids, ethylenediamine, hexamethylenediamine, cyclohexanediamine, xylylenediamine, 6-aminocaproic acid, 11-aminoundecanoic acid, 12-aminododecanoic acid, p-aminomethylbenzoic acid, caprolactam and ω-laurolactam; Preferably, the other comonomers account for 0.001-10% of the total mass of the synthetic raw materials of the polyamide 56 / 6 copolymer; The additives preferably include any one or more of a matting agent, a flame retardant, an antioxidant, an ultraviolet absorber, an infrared absorber, a crystal nucleating agent, a fluorescent brightener and an antistatic agent; Preferably, the additive is added in an amount of 0.001-10% of the total mass of the synthetic raw materials of the polyamide 56 / 6 copolymer.

5. The parallel composite elastic fiber according to claim 1, characterized in that: The parallel composite elastic fibers meet one or more of the following conditions: (1) The melting point of the polyamide 56 / 6 copolymer is 180-260°C, preferably 190-250°C, and more preferably 200-240°C; (2) The terminal amino group content of the polyamide 56 / 6 copolymer is 30-65 mmol / kg, preferably 40-60 mmol / kg, and more preferably 45-55 mmol / kg; (3) the oligomer content in the polyamide 56 / 6 copolymer is less than 1.5 wt %; (4) The water content of the polyamide 56 / 6 copolymer is 50-1300 ppm, preferably 200-1000 ppm, more preferably 300-800 ppm, and further more preferably 400-700 ppm; (5) The relative viscosity of the polyamide 56 / 6 copolymer and 96 wt % sulfuric acid is 2.0-3.5, preferably 2.1-3.3, and more preferably 2.3-3.0; (6) The polyamide 5X is one or more of polyamide 510, polyamide 511, polyamide 512, polyamide 513, polyamide 514, polyamide 515 and polyamide 516; (7) The polyamide 6X is one or more of polyamide 610, polyamide 611, polyamide 612, polyamide 613, polyamide 614, polyamide 615 and polyamide 616; (8) the moisture content of the second parallel structure is 50-1300 ppm, preferably 200-1000 ppm, more preferably 300-800 ppm, and even more preferably 400-700 ppm; and, (9) The relative viscosity of the second parallel structure and 96 wt % sulfuric acid is 1.5-3.0, preferably 1.6-2.

7.

6. A method for preparing the parallel composite elastic fiber according to any one of claims 1 to 5, characterized in that: It includes the following steps: S1 the first parallel structure material and the second parallel structure material are melted and then converged for spinning to obtain parallel composite primary fibers; The parallel composite primary fibers described in S2 are pre-treated and drawn to obtain parallel composite elastic fibers.

7. The method for preparing the parallel composite elastic fiber according to claim 6, characterized in that: The preparation method meets one or more of the following conditions: (1) The materials of the first parallel structure are melted in a first screw extruder, and the first screw extruder preferably includes the following five temperature zones: The temperature of zone 1 is 180-240℃; The temperature of zone 2 is 200-250℃; The temperature of zone 3 is 210-260℃; The temperature of zone 4 is 220-270℃; The temperature of zone 5 is 230-280℃; (2) The material of the second parallel structure is melted in a second screw extruder, and the second screw extruder preferably includes the following five temperature zones: The temperature of zone 1 is 180-260℃; The temperature of zone 2 is 200-270℃; The temperature of zone 3 is 210-280℃; The temperature of zone 4 is 230-290℃; The temperature of zone 5 is 240-290℃; (3) In S1, the convergent spinning process is that the melts are transported to the composite spinning box through the melt pipes respectively, and after entering the assembly, they are diverted by the composite spinneret and bonded together at the composite spinneret to obtain the parallel composite primary fibers; (4) In S1, the pressure of the spinning assembly during the convergent spinning process is 10-28 MPa, preferably 13-25 MPa, and more preferably 15-20 MPa; and, (5) In S1, the temperature of the spinning box during the convergent spinning process is 240-280°C.

8. The method for preparing the parallel composite elastic fiber according to claim 7, characterized in that: The preparation method satisfies (1) and / or (2) of the following conditions: (1) The composite spinneret is a circular spinneret or an 8-shaped spinneret. (2) The number of holes of the composite spinneret is 10-100f.

9. The method for preparing the parallel composite elastic fiber according to claim 8, characterized in that: The preparation method meets one or more of the following conditions: (1) The 8-shaped spinneret is provided with a plurality of spinneret holes, wherein the spinneret holes include two parallel circular holes; The center distance D of the two parallel circles is preferably 0.28-0.6 mm, more preferably 0.3-0.55 mm, for example 0.32-0.45 mm; The radius r of the two parallel circles is preferably 0.1-0.3 mm, more preferably 0.12-0.28 mm; The spinneret hole D-2r is preferably 0.03-0.14 mm, more preferably 0.08-0.12 mm; (2) The radius r of the circular spinneret is preferably 0.1-0.3 mm, more preferably 0.12-0.28 mm; and, (3) The number of holes of the composite spinneret is 25-100f, preferably 35-60f.

10. Use of the parallel composite elastic fiber according to any one of claims 1 to 5 in fabrics.

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