Method for producing high-bulk polyester composite fiber

Abstract

The present application relates to a kind of preparation methods of high loft polyester composite fiber, with nano calcium carbonate blend reinforced modified polymer as skin layer component, PET, PTT or PBT as core layer component, after spinning, winding using sheath-core spinning process, sequentially through preliminary drawing, acidification treatment, directional hot air treatment, cooling setting, re-drawing high loft polyester composite fiber is prepared;The melting point of skin layer component is lower than core layer component;Acid liquor is one or more above in dilute sulfuric acid, dilute hydrochloric acid and dilute nitric acid with pH 2.5-3.5;The present application utilizes the chemical property of nano calcium carbonate in acid liquor and forms porous structure, under the double influence of gas external force and porous structure, the degree of three-dimensional crimping inside sheath-core composite fiber is further increased, and then the crimping performance, loft performance, mechanical property and moisture absorption and quick drying performance of composite fiber are improved, and the overall process is simple and controllable.

Description

Technical Field

[0001] This invention belongs to the field of composite fiber technology and relates to a method for preparing high-loft polyester composite fiber. Background Technology

[0002] Polyester fiber, currently the largest variety of synthetic fiber, possesses advantages such as high breaking strength, high elastic modulus, good heat resistance, and good light resistance, making it widely used in apparel and industrial applications. With the continuous improvement of people's living standards, the requirements for various properties of polyester fibers are also increasing, such as crimp properties and mechanical properties. The crimp property of the fiber brings better softness, high bulkiness, and good resilience, and also improves the warmth retention of fabrics.

[0003] To achieve the required crimp performance and high bulkiness of polyester fibers, a foaming process is generally required. This process creates a primary porous structure on the surface of the filaments. Then, directional hot air is used to cause the filaments to become oriented and crimped, completing the continuous crimping and shaping process. Finally, the filaments are cut to obtain porous fibers with a crimped structure. Commonly used foaming agents include azodicarbonamide, azobisisobutyronitrile, dinitrosopentanetamine, p-toluenesulfonyl hydrazine, pentane, and hydrofluoroalkanes. However, current foaming processes create a microporous structure in conventional single-component polyester filaments under the action of gases generated by foaming agents. This foaming treatment on the basis of monofilaments results in defects in the microporous structure of the monofilaments, which, while improving crimp performance, drastically reduces mechanical properties.

[0004] For example, patent CN116695282A provides a porous, highly absorbent polyester fiber, its preparation method, and its applications. It involves blending PET polyester chips, porous solid materials, organic bentonite, sodium bicarbonate masterbatch, coupling agents, and cellulose, followed by melt spinning to prepare single-component polyester filaments. During the spinning process, the sodium bicarbonate masterbatch is heated, decomposing to generate gas. Simultaneously, the porous solid material creates numerous interconnected micro-network channels within the polyester fiber, improving its absorbency and softness. However, conventional single-component melt spinning processes generate microporous structures through internal foaming. Without a main structural support, these internal defects easily lead to poor weather resistance. Even though this application improves the stability of the internal structure by adding a coupling agent, the fabric prepared using this method loses 6% of its weight after 30 washes, and the antibacterial rate maintained after washing is low, indicating that the microporous structure generated by this foaming process is unstable.

[0005] To improve the crimp properties and bulkiness of polyester fibers, those skilled in the art have made numerous attempts. For example, patent CN202211031995.9 provides a porous fiber with a wool-like crimp structure and its preparation method. The method involves immersing PE filaments in a polymer foaming solution for ultrasonic treatment, followed by rotary impregnation, solvent separation, drying, and hot air setting of the filaments. Finally, the filaments are cut to obtain the desired fiber. Fabrics spun and woven from this fiber have a thermal resistance of 0.15–0.4 μm. 2 The K / W ratio and crimp rate are controllable within the range of 10% to 60%. This method keeps the core filament unchanged to provide mechanical strength. However, this method uses filament as the core layer, covers the surface with a sheath polymer foaming solution, and then separates the foaming solution to prepare porous sheath-core composite fibers through post-solution processing. The sheath-core composite fibers prepared by this method have poor compatibility between the sheath and core layers. The sheath and core layers are not melt-extruded at the same time, and the interface is easy to peel off, so the mechanical properties are poor.

[0006] In addition, there are other methods to achieve the required crimp performance and high bulkiness of polyester fibers, but these also have drawbacks in mechanical properties. For example, patent CN200610117221.2 introduces a PA6 / PU composite three-dimensional crimp fiber and its preparation method. The fiber, which is a composite of PA6 sheath and PU core, is prepared through processes such as drying, spinning, and stretching to produce a fiber with permanent three-dimensional crimp characteristics. The performance indicators are: fiber elongation ≥30%, fiber crimp number ≥10 / 25mm, and excellent elasticity and high crimp. Although the bicomponent sheath-core structure can improve the crimp performance, it also leads to uneven axial stress, easy interface peeling, and lower mechanical properties compared to single-component fibers, thus limiting its applications.

[0007] Therefore, it is of great significance to study a method for preparing high-loft polyester composite fibers to solve the problem that existing preparation technologies cannot simultaneously achieve high loft, high crimp performance, and excellent mechanical strength in polyester composite fibers. Summary of the Invention

[0008] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a method for preparing high-loft polyester composite fibers.

[0009] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0010] A method for preparing high-loft polyester composite fiber, using a polymer reinforced and modified with nano-calcium carbonate as the sheath component, and PET, PTT or PBT as the core component, is used to spin and wind the fiber using a sheath-core spinning process, followed by preliminary stretching, acidification treatment, orientation (i.e., the same direction) hot blowing treatment, cooling and shaping, and re-stretching to obtain the high-loft polyester composite fiber.

[0011] The melting point of the cortex component is lower than that of the core component;

[0012] The acid solution used in the acidification treatment is one or more of the following: dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid, with a pH of 2.5 to 3.5.

[0013] As a preferred technical solution:

[0014] The preparation method of the high-loft polyester composite fiber described above involves obtaining the polymer modified by nano-calcium carbonate blending by melt-blending and extruding PE or PP with nano-calcium carbonate and dispersant in a twin-screw extruder and granulating the mixture at a melt-blending temperature of 200–250°C.

[0015] In the preparation method of the high-loft polyester composite fiber described above, the content of nano-calcium carbonate in the polymer modified by nano-calcium carbonate blending is 0.5-2 wt%, and the mass ratio of nano-calcium carbonate to dispersant is 1-3:1.

[0016] The preparation method of the high-loft polyester composite fiber described above uses nano-calcium carbonate with a particle size of 40-80 nm; the dispersant is polyethylene wax, polypropylene wax or EVA wax; and the intrinsic viscosity of PET, PTT or PBT is 0.65-0.85 dl / g.

[0017] In the preparation method of the high-loft polyester composite fiber described above, the mass ratio of the sheath to the core layer is 2-4:8-6.

[0018] The method for preparing a high-loft polyester composite fiber as described above involves a preliminary stretching with a stretch ratio of 1.5 to 2.5 and a stretching speed of 600 to 800 m / min; and a subsequent stretching with a stretch ratio of 2 to 4 and a stretching speed of 800 to 1000 m / min.

[0019] The method for preparing a high-loft polyester composite fiber as described above involves acidification treatment in an acid bath for 5 to 10 minutes, with the length of the acid bath being 0.5 to 1 meter.

[0020] Directional hot air treatment is carried out in a hot air box with a temperature of 60-70℃, a length of 0.5-1m, a fixed air direction, and a treatment time of 5-10 minutes.

[0021] Cooling and shaping are carried out in a water bath with a temperature of 5-10℃ and a length of 2-3m.

[0022] After initial stretching, the core-sheath composite fiber formed by spinning and winding is acidified in an acid bath, directional hot blowing in a hot air blowing box to cause directional curling and produce a porous structure, and then enters a water bath for cooling and shaping. After further stretching, high-loft polyester composite fiber is finally prepared.

[0023] The method for preparing high-loft polyester composite fibers as described above involves a porous structure, primarily distributed on the surface of the sheath layer and with a few distributed at the interface between the sheath and core layers. The pore size of this porous structure is 0.1–0.5 μm. Smaller nano-calcium carbonate particles result in a larger specific surface area, more vigorous reaction with acid, and the generation of more CO2 gas. This leads to greater internal stress and, consequently, larger pore sizes. However, larger pore sizes are not always better; there is a suitable range. Existing supercritical CO2 foaming technology produces pores ranging from 0.1 to 10 μm, while the CO2 gas generated in this invention exhibits lower internal stress, resulting in smaller pore sizes of 0.1–0.5 μm, which effectively enhances three-dimensional crimp without significantly altering fiber strength.

[0024] The high-loft polyester composite fiber prepared by the above-described method has the following properties: tensile strength ≥ 3 cN / dtex, elongation at break ≥ 70% (tensile strength and elongation at break are tested according to GB / T 14460-2015), crimp elasticity ≥ 80%, crimp recovery rate ≥ 90% (crimp elasticity and crimp recovery rate are tested according to GB / T 14338-2022), bulkiness ≥ 12 cm / 30 g (bulkness is tested according to GB / T 10288-2016), water absorption rate ≥ 30% / s, and moisture absorption and quick-drying performance rating ≥ 3 (water absorption rate and moisture absorption and quick-drying performance are tested according to GB / T 21655.2-2019).

[0025] Invention principle:

[0026] For non-3D crimped (planar crimped) fibers, there is no cross-linking effect between fibers, and the fibers easily stick together tightly, making it difficult to create gaps. However, due to their spring-like shape, 3D crimped fibers are stretched apart, resulting in large gaps between the fibers. Therefore, 3D crimped fibers have obvious bulkiness. The core-sheath composite spinning process utilizes the difference in shrinkage rates between the inner and outer layers, resulting in internal stress and three-dimensional crimping. This process exhibits excellent crimping performance. After acid treatment, the nano-calcium carbonate in the sheath layer decomposes and releases CO2. This creates microporous defects in situ, while gas diffusion generates minute internal stresses and forms a porous structure. The formation of this porous structure further enhances the degree of three-dimensional spiral crimping within the core-sheath composite fiber. Under the dual influence of external gas force and the formation of the porous structure, the degree of three-dimensional crimping within the core-sheath composite fiber is further increased, strengthening the three-dimensional crimping and increasing the gaps between the three-dimensional crimped fibers. This improves the fiber's bulkiness, increases the number of fiber crimps per unit area, and enhances the crimp rate of the bicomponent fibers, resulting in a highly bulky fiber web that achieves a crimped and fluffy effect. The presence of a porous structure accelerates the entry and exit of moisture, thereby improving the moisture absorption and quick-drying performance. Furthermore, the residual nano-calcium carbonate acts as a reinforcing material for the outer layer, while the unaffected core layer provides mechanical properties, which can have a positive effect on the physical properties of the composite fiber, enabling the composite fiber to balance high bulkiness, crimping performance, and mechanical properties.

[0027] In the preparation process of the fiber of the present invention, it undergoes preliminary stretching followed by acidification treatment. The preliminary stretching results in high crystallinity of the product after preliminary stretching, while the PE or PP outer layer has strong acid resistance. The product after preliminary stretching has a short residence time in acid solution. These factors ensure that the fiber of the present invention will not have its mechanical properties weakened due to acid corrosion after acidification treatment during the preparation process.

[0028] Existing foaming processes involve creating a microporous structure in conventional single-component polyester filaments through the action of a foaming agent-generated gas. This foaming treatment on top of the monofilaments results in defects in the microporous structure, which, while improving crimp performance, drastically reduces mechanical properties. For example, in patent CN116695282A, sodium bicarbonate in single-component melt-spun fibers reacts at 255°C to release gas, leading to internal structural defects and poor weather resistance. Furthermore, the crimp performance and bulkiness of single-component fibers produced using existing foaming processes are not as high as those of core-sheath composite fibers. If the foaming agent is used on core-sheath fibers, the large amount of gas from the foaming agent causes the polymer to expand and create a microporous structure, easily leading to delamination between the sheath and core layers. This invention utilizes the disappearance of nano-calcium carbonate and gas diffusion to create a porous structure based on core-sheath composite fibers. Nano-calcium carbonate is used in the sheath layer as a gas generator to slowly release gas from the inside, creating a microporous structure. At low temperatures, the nano-calcium carbonate reacts with acid to generate calcium salts, water, and CO2 gas. The reacted nano-calcium carbonate creates defective micropores, which allow gas to diffuse smoothly along the micropores to the outer layer, reducing the impact on the interface and increasing the size of the micropores. The unreacted nano-calcium carbonate also acts as reinforcing particles to improve the mechanical properties of the fiber. At the same time, the core layer provides mechanical support, maintaining excellent mechanical properties.

[0029] Beneficial effects:

[0030] (1) The present invention provides a method for preparing a high-loft polyester composite fiber, in which nano-calcium carbonate is selected as a modified monomer. Taking advantage of its chemical property of releasing CO2 in acidic solution, the core-sheath composite fiber is subjected to internal decomposition of nano-calcium carbonate and gas release at a temperature higher than Tg to generate a porous structure. Under the dual influence of gas external force and porous structure, the degree of three-dimensional crimping inside the core-sheath composite fiber is further increased, thereby improving the crimping performance and loft performance of the composite fiber, and also improving the mechanical properties and moisture absorption and quick-drying performance to a certain extent.

[0031] (2) The present invention provides a method for preparing high-loft polyester composite fiber, which adopts a core-sheath composite spinning method. One of the blended modified PE or PP reinforced with nano-calcium carbonate is used as the sheath, and one of PET, PTT or PBT is used as the core. The high-loft core-sheath composite fiber is obtained by post-treatment processes such as acidification in an acid bath and directional hot blowing in a hot blowing box. This method solves the problems of complex preparation process and single raw materials for high-loft fiber, and the overall process is simple and controllable.

[0032] (3) Compared with existing hollow fibers, the high-loft polyester composite fiber prepared by the present invention has stable physical and mechanical properties, good mechanical strength, good lubricity and hand feel, high loft and good wearability, and can be widely used in home textiles, carpets, down jackets and other wearable fields. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of high-loft polyester composite fiber;

[0034] Figure 2 This is a SEM image of the porous structure of the high-loft polyester composite fiber in Example 4;

[0035] Among them, 1-cortex, 2-core layer, 3-porous structure. Detailed Implementation

[0036] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0037] The testing standards / methods involved in this invention are as follows:

[0038] Breaking strength and elongation at break: tested according to GB / T 14460-2015;

[0039] Curl elasticity and curl recovery rate: tested according to GB / T 14338-2022;

[0040] Loft: Tested according to GB / T 10288-2016 Test Method for Down and Feathers;

[0041] Water absorption rate and moisture-wicking performance rating: tested according to GB / T 21655.2-2019.

[0042] Example 1

[0043] A method for preparing high-loft polyester composite fiber, the specific steps of which are as follows:

[0044] (1) Preparation of raw materials:

[0045] PE: Manufacturer: BASF, Grade: 2420H;

[0046] Nano-calcium carbonate: average particle size is 40nm;

[0047] Dispersant: Polyethylene wax, Manufacturer: Merrill, Brand: M87671;

[0048] PET: Intrinsic viscosity is 0.68 dl / g, manufacturer: Yizheng Chemical Fiber, grade: FC520;

[0049] Acid solution: dilute sulfuric acid with a pH of 2.5;

[0050] (2) PE was melt-blended and extruded with nano-calcium carbonate and dispersant at a mass ratio of 1:1 in a twin-screw extruder and granulated to obtain nano-calcium carbonate blended reinforced PE. The melt blending temperature was 200℃. The content of nano-calcium carbonate in the nano-calcium carbonate blended reinforced PE was 1wt%.

[0051] (3) PE reinforced and modified with nano-calcium carbonate is used as the skin layer component and PET is used as the core layer component. After spinning and winding using the skin-core spinning process, it is then subjected to preliminary drawing with a drawing ratio of 1.5 and a drawing speed of 600m / min. The mass ratio of the skin layer to the core layer is 2:8.

[0052] (4) The product after preliminary stretching is acidified in an acid bath with a length of 0.5m for 10min;

[0053] (5) The acidified product was subjected to directional hot air blowing for 10 min in a hot air blowing box with a temperature of 60℃ and a length of 0.5m;

[0054] (6) The product after directional hot air treatment is cooled and shaped in a water bath with a length of 2m and a water bath temperature of 5℃.

[0055] (7) The product after cooling and shaping is further drawn at a draw ratio of 2 and a draw speed of 800 m / min to obtain high-loft polyester composite fiber.

[0056] like Figure 1 As shown, the obtained high-loft polyester composite fiber is a core-sheath composite fiber. The sheath 1 is PE reinforced and modified with nano-calcium carbonate, and the core 2 is PET. The high-loft polyester composite fiber has a porous structure 3 with an average pore size of 0.1 μm. The high-loft polyester composite fiber has a breaking strength of 4.1 cN / dtex, a breaking elongation of 72%, a crimp elasticity of 83%, a crimp recovery rate of 92%, a bulkiness of 12.5 cm / 30 g, a water absorption rate of 35% / s, and a moisture absorption and quick-drying performance rating of level 3.

[0057] Example 2

[0058] A method for preparing high-loft polyester composite fiber, the specific steps of which are as follows:

[0059] (1) Preparation of raw materials:

[0060] PP: Manufacturer: Qilu Petrochemical, Grade: EPS30R;

[0061] Nano-calcium carbonate: average particle size is 45nm;

[0062] Dispersant: Polypropylene wax, Manufacturer: Clariant, Model: 1502;

[0063] PTT: Intrinsic viscosity is 0.75 dl / g, manufacturer: DuPont, model 3301;

[0064] Acid solution: dilute hydrochloric acid with a pH of 2.8;

[0065] (2) PP was melt-blended and extruded with nano-calcium carbonate and dispersant at a mass ratio of 1.5:1 in a twin-screw extruder and granulated to obtain PP with nano-calcium carbonate blend reinforcement and modification. The melt blending temperature was 210℃. The content of nano-calcium carbonate in the PP with nano-calcium carbonate blend reinforcement and modification was 1.2wt%.

[0066] (3) PP reinforced and modified with nano-calcium carbonate is used as the skin layer component and PTT is used as the core layer component. After spinning and winding using the skin-core spinning process, it is then subjected to preliminary drawing with a drawing ratio of 1.7 and a drawing speed of 650 m / min. The mass ratio of the skin layer to the core layer is 3:7.

[0067] (4) The product after preliminary stretching is acidified in an acid bath with a length of 0.6m for 9 minutes;

[0068] (5) The acidified product was subjected to directional hot air blowing for 9 minutes in a hot air blowing box with a temperature of 62℃ and a length of 0.6m;

[0069] (6) The product after directional hot air treatment is cooled and shaped in a water bath with a length of 2.2m and the temperature of the water bath is 6℃;

[0070] (7) The product after cooling and setting is further drawn to obtain high-loft polyester composite fiber by drawing ratio of 2.5 and drawing speed of 850m / min.

[0071] The obtained high-loft polyester composite fiber has a porous structure with an average pore size of 0.25 μm. The high-loft polyester composite fiber has a breaking strength of 3.8 cN / dtex, a breaking elongation of 81%, a crimp elasticity of 89%, a crimp recovery rate of 95%, a bulkiness of 13.5 cm / 30 g, a water absorption rate of 53% / s, and a moisture absorption and quick-drying performance rating of 4.

[0072] Example 3

[0073] A method for preparing high-loft polyester composite fiber, the specific steps of which are as follows:

[0074] (1) Preparation of raw materials:

[0075] PE: Manufacturer: BASF, Grade: 2420H;

[0076] Nano-calcium carbonate: average particle size is 50nm;

[0077] Dispersant: EVA wax, manufacturer: BASF, brand: LUWAX EVA3;

[0078] PBT: Intrinsic viscosity is 0.77 dl / g, manufacturer: DuPont, grade: FGS600F40 NC010;

[0079] Acid solution: dilute nitric acid with a pH of 3;

[0080] (2) PE was melt-blended and extruded with nano-calcium carbonate and dispersant at a mass ratio of 2:1 in a twin-screw extruder and granulated to obtain PE with nano-calcium carbonate blend reinforcement and modification. The melt blending temperature was 220℃. The content of nano-calcium carbonate in the PE with nano-calcium carbonate blend reinforcement and modification was 1.4wt%.

[0081] (3) PE reinforced and modified with nano-calcium carbonate is used as the skin layer component and PBT is used as the core layer component. After spinning and winding using the skin-core spinning process, it is then subjected to preliminary drawing with a drawing ratio of 2 and a drawing speed of 700 m / min. The mass ratio of the skin layer to the core layer is 4:6.

[0082] (4) The product after preliminary stretching is acidified in an acid bath with a length of 0.7m for 8 minutes;

[0083] (5) The acidified product was subjected to directional hot air blowing treatment for 8 minutes in a hot air blowing box with a temperature of 64℃ and a length of 0.7m.

[0084] (6) The product after directional hot air treatment is cooled and shaped in a water bath with a length of 2.4m and the temperature of the water bath is 7℃;

[0085] (7) The product after cooling and shaping is further drawn with a draw ratio of 3 and a draw speed of 900 m / min to obtain high-loft polyester composite fiber.

[0086] The obtained high-loft polyester composite fiber has a porous structure with an average pore size of 0.4 μm. The high-loft polyester composite fiber has a breaking strength of 3.5 cN / dtex, a breaking elongation of 85%, a crimp elasticity of 87%, a crimp recovery rate of 94%, a bulkiness of 14 cm / 30 g, a water absorption rate of 63% / s, and a moisture absorption and quick-drying performance rating of 4.

[0087] Example 4

[0088] A method for preparing high-loft polyester composite fiber, the specific steps of which are as follows:

[0089] (1) Preparation of raw materials:

[0090] PP: Manufacturer: Qilu Petrochemical, Grade: EPS30R;

[0091] Nano-calcium carbonate: average particle size is 60nm;

[0092] Dispersant: Polyethylene wax, Manufacturer: Merrill, Brand: M87671;

[0093] PET: Intrinsic viscosity is 0.71 dl / g, manufacturer: Yizheng Chemical Fiber, grade: FC520;

[0094] Acid solution: dilute sulfuric acid with a pH of 3.2;

[0095] (2) PP was melt-blended and extruded with nano-calcium carbonate and dispersant at a mass ratio of 2.5:1 in a twin-screw extruder and granulated to obtain PP with nano-calcium carbonate blend reinforcement and modification. The melt blending temperature was 230℃. The content of nano-calcium carbonate in the PP with nano-calcium carbonate blend reinforcement and modification was 1.6wt%.

[0096] (3) PP reinforced and modified with nano-calcium carbonate is used as the skin layer component and PET is used as the core layer component. After spinning and winding using the skin-core spinning process, it is then subjected to preliminary drawing with a drawing ratio of 2.2 and a drawing speed of 750m / min. The mass ratio of the skin layer to the core layer is 4:6.

[0097] (4) The product after preliminary stretching is acidified in an acid bath with a length of 0.8m for 7 minutes;

[0098] (5) The acidified product was subjected to directional hot air blowing treatment for 7 minutes in a hot air blowing box with a temperature of 66℃ and a length of 0.8m;

[0099] (6) The product after directional hot air treatment is cooled and shaped in a water bath with a length of 2.6m and the temperature of the water bath is 8℃;

[0100] (7) The product after cooling and setting is further drawn to obtain high-loft polyester composite fiber by drawing ratio of 3.5 and drawing speed of 950m / min.

[0101] like Figure 2 As shown, the prepared high-loft polyester composite fiber has a porous structure with an average pore size of 0.5 μm. The high-loft polyester composite fiber has a breaking strength of 3.9 cN / dtex, a breaking elongation of 76%, a crimp elasticity of 88%, a crimp recovery rate of 93%, a bulkiness of 14.5 cm / 30 g, a water absorption rate of 64% / s, and a moisture absorption and quick-drying performance rating of 4.

[0102] Example 5

[0103] A method for preparing high-loft polyester composite fiber, the specific steps of which are as follows:

[0104] (1) Preparation of raw materials:

[0105] PE: Manufacturer: BASF, Grade: 2420H;

[0106] Nano-calcium carbonate: average particle size is 70nm;

[0107] Dispersant: Polypropylene wax, Manufacturer: Clariant, Model: 1502;

[0108] PTT: Intrinsic viscosity is 0.8 dl / g, manufacturer: DuPont, model 3301;

[0109] Acid solution: a mixed solution of dilute sulfuric acid and dilute hydrochloric acid in a volume ratio of 1:1, with a pH of 3.4;

[0110] (2) PE was melt-blended and extruded with nano-calcium carbonate and dispersant at a mass ratio of 3:1 in a twin-screw extruder and granulated to obtain PE with nano-calcium carbonate blend reinforcement and modification. The melt blending temperature was 240℃. The content of nano-calcium carbonate in the PE with nano-calcium carbonate blend reinforcement and modification was 1.8wt%.

[0111] (3) PE reinforced and modified with nano-calcium carbonate is used as the skin layer component and PTT is used as the core layer component. After spinning and winding using the skin-core spinning process, it is then subjected to preliminary drawing with a drawing ratio of 2.4 and a drawing speed of 780m / min. The mass ratio of the skin layer to the core layer is 3:7.

[0112] (4) The product after preliminary stretching is acidified in an acid bath with a length of 0.9m for 6 minutes;

[0113] (5) The acidified product was subjected to directional hot air blowing treatment for 6 min in a hot air blowing box with a temperature of 68℃ and a length of 0.9m;

[0114] (6) The product after directional hot air treatment is cooled and shaped in a water bath with a length of 2.8m and the temperature of the water bath is 9℃;

[0115] (7) The product after cooling and setting is further drawn to obtain high-loft polyester composite fiber by drawing ratio of 3.8 and drawing speed of 980m / min.

[0116] The obtained high-loft polyester composite fiber has a porous structure with an average pore size of 0.3 μm. The high-loft polyester composite fiber has a breaking strength of 3.6 cN / dtex, a breaking elongation of 84%, a crimp elasticity of 90%, a crimp recovery rate of 96%, a bulkiness of 14 cm / 30 g, a water absorption rate of 56% / s, and a moisture absorption and quick-drying performance rating of 4.

[0117] Example 6

[0118] A method for preparing high-loft polyester composite fiber, the specific steps of which are as follows:

[0119] (1) Preparation of raw materials:

[0120] PP: Manufacturer: Qilu Petrochemical, Grade: EPS30R;

[0121] Nano-calcium carbonate: average particle size is 80nm;

[0122] Dispersant: EVA wax, manufacturer: BASF, brand: LUWAX EVA3;

[0123] PBT: Intrinsic viscosity is 0.81 dl / g, manufacturer: DuPont, grade: FGS600F40 NC010;

[0124] Acid solution: a mixed solution of dilute hydrochloric acid and dilute nitric acid in a volume ratio of 1:1, with a pH of 3.5;

[0125] (2) PP was melt-blended and extruded with nano-calcium carbonate and dispersant at a mass ratio of 3:1 in a twin-screw extruder and granulated to obtain nano-calcium carbonate blended reinforced PP. The melt blending temperature was 250℃. The content of nano-calcium carbonate in the nano-calcium carbonate blended reinforced PP was 2wt%.

[0126] (3) PP reinforced and modified with nano-calcium carbonate is used as the skin layer component and PBT is used as the core layer component. After spinning and winding using the skin-core spinning process, it is then subjected to preliminary drawing with a drawing ratio of 2.5 and a drawing speed of 800 m / min. The mass ratio of the skin layer to the core layer is 2:8.

[0127] (4) The product after preliminary stretching is acidified in an acid bath with a length of 1m for 5min;

[0128] (5) The acidified product was subjected to directional hot air blowing for 5 minutes in a hot air blowing box with a temperature of 70℃ and a length of 1m.

[0129] (6) The product after directional hot air treatment is cooled and shaped in a water bath with a length of 3m and a water bath temperature of 10℃.

[0130] (7) The product after cooling and shaping is further drawn by a drawing ratio of 4 and a drawing speed of 1000m / min to obtain high-loft polyester composite fiber.

[0131] The obtained high-loft polyester composite fiber has a porous structure with an average pore size of 0.2 μm. The high-loft polyester composite fiber has a breaking strength of 3.7 cN / dtex, a breaking elongation of 83%, a crimp elasticity of 82%, a crimp recovery rate of 91%, a bulkiness of 13.6 cm / 30g, a water absorption rate of 35% / s, and a moisture absorption and quick-drying performance rating of level 3.

Claims

1. A method for preparing a high-loft polyester composite fiber, characterized in that: High-loft polyester composite fiber is obtained by using a polymer modified with nano-calcium carbonate as the sheath component and PET, PTT or PBT as the core component. After spinning and winding using a sheath-core spinning process, the fiber is then subjected to preliminary stretching, acidification treatment, directional hot blowing treatment, cooling and shaping, and re-stretching. The melting point of the cortex component is lower than that of the core component; The acid solution used in the acidification treatment is one or more of the following: dilute sulfuric acid, dilute hydrochloric acid, and dilute nitric acid with a pH of 2.5 to 3.

5. The tensile strength of high-loft polyester composite fiber is ≥3.5cN / dtex, and the elongation at break is ≥70%.

2. The method for preparing a high-loft polyester composite fiber according to claim 1, characterized in that, The polymer reinforced and modified with nano-calcium carbonate is obtained by melt-blending and extruding PE or PP with nano-calcium carbonate and dispersant in a twin-screw extruder and then granulating. The melt blending temperature is 200~250℃.

3. The method for preparing a high-loft polyester composite fiber according to claim 2, characterized in that, The content of nano-calcium carbonate in the polymer reinforced by nano-calcium carbonate blend is 0.5~2wt%, and the mass ratio of nano-calcium carbonate to dispersant is 1~3:

1.

4. The method for preparing a high-loft polyester composite fiber according to claim 3, characterized in that, The nano-calcium carbonate has a particle size of 40~80nm; the dispersant is polyethylene wax, polypropylene wax or EVA wax; the intrinsic viscosity of PET, PTT or PBT is 0.65~0.85dl / g.

5. The method for preparing a high-loft polyester composite fiber according to claim 1, characterized in that, The mass ratio of the cortex to the core is 2~4:8~6.

6. The method for preparing a high-loft polyester composite fiber according to claim 1, characterized in that, The initial drawing ratio is 1.5~2.5, and the drawing speed is 600~800m / min; the secondary drawing ratio is 2~4, and the drawing speed is 800~1000m / min.

7. The method for preparing a high-loft polyester composite fiber according to claim 1, characterized in that, Acidification is carried out in an acid bath for 5-10 minutes, and the length of the acid bath is 0.5-1m. Directional hot air treatment is carried out in a hot air blowing box with a temperature of 60~70℃ and a length of 0.5~1m, and the directional hot air blowing treatment time is 5~10min; Cooling and shaping are carried out in a water bath with a temperature of 5~10℃ and a length of 2~3m.

8. The method for preparing a high-loft polyester composite fiber according to claim 1, characterized in that, The high-loft polyester composite fiber has a porous structure with a pore size of 0.1~0.5μm.

9. The method for preparing a high-loft polyester composite fiber according to claim 8, characterized in that, The high-loft polyester composite fiber has a crimp recovery rate of ≥90%, a loft of ≥12cm / 30g, a water absorption rate of ≥30% / s, and a moisture absorption and quick-drying performance rating of ≥3.

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