Preparation method of high-curling parallel type PET / PTT composite fiber

Abstract

The present application belongs to the technical field of PET / PTT composite fiber, and relates to a preparation method of high-curling parallel PET / PTT composite fiber. PET chips and PTT chips are respectively subjected to crystallization drying, melt extrusion, filtration and metering, then are combined, and then are subjected to a process flow of spinning through a composite component, cooling, oiling, pre-networking, a first hot roller group, a second hot roller group, a guide roller, main networking and winding to form a high-curling parallel PET / PTT composite fiber. The networkers used in pre-networking and main networking both comprise two nozzles arranged in an upper-lower manner. The spray holes of the upper nozzle are inclined to spray gas downward, and the spray holes of the lower nozzle are inclined to spray gas upward. The preparation method of the high-curling parallel PET / PTT composite fiber adopts a special asymmetric structure networker design, can make the PTT fiber fully exert excellent elastic properties, and solves the problem that fiber elasticity and breaking strength are difficult to be considered.

Description

Technical Field

[0001] This invention belongs to the field of PET / PTT composite fiber technology, and relates to a method for preparing highly crimped side-by-side PET / PTT composite fibers. Background Technology

[0003] In the largest civilian fiber sector, most fabrics utilize crimped fibers as weaving materials, leveraging the crimped structure to impart fluffiness, breathability, and a velvety feel. Fiber crimping is generally achieved through texturing single-component fibers or through self-crimping via bicomponent composite spinning. Bicomponent heterogeneous shrinkage fibers are among the more technologically advanced and high-value-added products in the differentiation of chemical fibers. PET / PTT side-by-side composite fibers are the earliest developed side-by-side heterogeneous shrinkage self-crimping fibers in the industry. PTT fibers exhibit excellent elasticity, stable elasticity, and a soft hand feel, but their strength is insufficient; while PET fibers possess excellent wrinkle resistance and shape retention, along with high strength and elastic recovery.

[0004] Patent CN109235019A discloses highly crimped elastic PET / PTT composite fibers and their preparation method. It states that the elasticity of PET / PTT composite fibers is related to their degree of crimp, and heat treatment conditions are a crucial factor affecting their crimp elasticity. Heat treatment under relaxation conditions can increase the crimp shrinkage rate of the composite fibers, but it reduces their crystallinity and orientation, leading to a decrease in tensile strength and thus lower mechanical properties. Under tension, crystallinity and orientation can be increased, but the crimp elongation and shrinkage rate decrease significantly, thereby reducing the elasticity of the composite fibers. To address this, the patent describes a process of alternating tension heat treatment to produce highly flexible PET / PTT composite fibers. The heat treatment time is 10-30 minutes. However, the relatively long heat treatment time is insufficient to meet the requirement that the heat treatment process in the current one-step PET / PTT production process be completed in a few seconds to tens of seconds, resulting in poor production continuity. The 10-30 minute heat treatment time is strictly controlled, especially in continuous production stages. If this time range is exceeded, the curlability will be substandard or the strength will be damaged.

[0005] Patent CN115522267A discloses a composite fiber with high fleece feel and elasticity, its preparation method, and its application. It mentions that to achieve the effect of one bundle of filaments winding on the inside and another bundle on the outside, ultimately resulting in a better fleece feel on the fabric, this patent involves a set of bicomponent fibers passing through a pre-network → first hot roller, then merging with another bundle of monofilaments that has not passed through the first hot roller before entering the second hot roller. Because this monofilament has not passed through the first hot roller and has not been stretched, it does not generate sufficient tension and remains in a relaxed state. When passing through the main network, it will wind around the outside of the other set of bicomponent fibers. However, since it has not been stretched and shaped by the hot roller, this monofilament is in a low-orientation, high-shrinkage state, exhibiting low fiber breaking strength, ultimately reducing the breaking strength of the composite fiber. Simultaneously, to achieve the winding effect, this patent combines bicomponent fibers with monofilaments, also reducing the crimp shrinkage rate of the composite fiber.

[0006] Therefore, it is of great significance to study a method for preparing highly crimped side-by-side PET / PTT composite fibers in order to solve the problems existing in the prior art. Summary of the Invention

[0007] The purpose of this invention is to solve the problems existing in the prior art and provide a method for preparing highly crimped side-by-side PET / PTT composite fibers.

[0008] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0009] A method for preparing a high crimped side-by-side PET / PTT composite fiber involves PET chips and PTT chips being crystallized and dried, melt-extruded, filtered and metered, then combined, and then processed through a composite component spinning → cooling → oiling → pre-networking → first hot roller group → second hot roller group → guide roller → main network → winding to obtain a high crimped side-by-side PET / PTT composite fiber.

[0010] Both the pre-network and the main network use networkers that contain two nozzles arranged vertically; the nozzle above sprays air downwards at an angle, while the nozzle below sprays air upwards at an angle.

[0011] In the pre-network device, the pressure of the air jet from the upper nozzle is 0.05~0.07MPa, and the pressure of the air jet from the lower nozzle is 0.03~0.04MPa;

[0012] The nozzle at the top is tilted downwards and sprays air at a pressure of 0.05~0.07MPa. When the pressure is higher than 0.07MPa, network nodes are easily formed, resulting in insufficient heating of the composite fiber when it passes through the hot roller, which affects its relaxation effect. That is, it inhibits the crimping and shrinkage of PTT fiber, ultimately affecting the elasticity and crimping shrinkage of the composite fiber. When the air pressure is lower than 0.05MPa, since the air is blown towards the fiber bundle from the top and bottom in a cross manner, the airflow will cancel out the vertical force with the fiber bundle, resulting in a "static pressure zone" in the fiber bundle between the two nozzles, which affects the oil permeability of the fiber.

[0013] The nozzle at the bottom is tilted upward to spray air at a pressure of 0.03~0.04MPa. Since the function of the nozzle at the bottom is to buffer the tension fluctuations from spinning and winding, which can cause fuzzing when PTT fibers come into contact with the ceramic part, the PTT fibers are prone to deviating from the center of the pre-networker when the pressure is below 0.03MPa or above 0.04MPa, resulting in fuzzing.

[0014] In the network device used in the main network, the pressure of the upper nozzle is 0.3~0.4MPa, and the pressure of the lower nozzle is 0.2~0.25MPa.

[0015] The nozzle at the top is tilted downwards and sprays air at a pressure of 0.3~0.4MPa. When the pressure is below 0.3MPa, the airflow inside the networker is insufficient, which makes it impossible to form network nodes and blow the lighter and more shrinkable PTT fibers to the outside of the fiber bundle. This results in a more disordered spiral crimp structure of the PET / PTT composite fiber and reduced crimp shrinkage. When the pressure is above 0.4MPa, the airflow pressure inside the networker is too high, which can easily lead to excessively dense network points in the fiber, reduced bulkiness of the composite fiber, and ultimately a stiffer fiber feel.

[0016] The nozzle at the bottom is tilted upwards to spray air at a pressure of 0.2~0.25MPa. If the air pressure at the bottom nozzle is less than 0.2MPa, the PTT fibers cannot be blown to the outside of the PET fibers, affecting the elasticity and crimp shrinkage of the composite fibers. If the air pressure at the bottom nozzle is greater than 0.25MPa, it is related to the downward movement of the filament bundle. The upward airflow creates a greater resistance opposite to the gravity and traction of the filament bundle, which can easily lead to unstable tension, resulting in fuzzy fibers or broken ends.

[0017] As a preferred technical solution:

[0018] The method for preparing highly crimped parallel PET / PTT composite fibers as described above uses a networker with a length of 6-8 cm, a nozzle diameter of 2-3 mm, and a distance of 2-3 cm between the upper and lower nozzles.

[0019] In the preparation method of the high crimped parallel PET / PTT composite fiber described above, in the pre-networking device, the nozzle of the upper nozzle is tilted at 25°~35° to spray air downwards, providing stable tension and airflow through the fiber bundle as it moves downwards, thus loosening it and improving the permeability of the oil agent; the nozzle of the lower nozzle is tilted at 30°~45° to spray air upwards, and this angle generates an upward supporting force to counteract the fluctuation of tension.

[0020] As described above, in the preparation method of a high-curl parallel PET / PTT composite fiber, the upper nozzle of the main network sprays air downward at an angle of 45° to 60°. This angle setting is beneficial to increase the impact force of the main network airflow on the fiber bundle and increase the network degree of the composite fiber. The network degree can ensure the stability of the spiral crimp knot of the composite fiber. The lower nozzle sprays air upward at an angle of 30° to 45°.

[0021] In the preparation method of the highly crimped side-by-side PET / PTT composite fiber described above, the mass ratio of PET chips to PTT chips is 45~55:55~45.

[0022] In the preparation method of the high crimped parallel PET / PTT composite fiber described above, the speed of the first hot roller group is 1800~2050m / min and the temperature is 78~82℃; the speed of the second hot roller group is 4100~4270m / min and the temperature is 160~170℃; the speed of the guide roller is 4080~4250m / min; and the winding speed is 4080~4250m / min.

[0023] The preparation method of the high crimped side-by-side PET / PTT composite fiber described above has the following characteristics: the crimped shrinkage rate of the high crimped side-by-side PET / PTT composite fiber is ≥45.3%, the crimp stability is ≥89.9%, the breaking strength is ≥3.5cN / dtex, the network density is 20±3 / cell / meter, and the filament degradation rate is ≤0.8%.

[0024] Invention principle:

[0025] This invention discloses a method for preparing highly crimped, parallel-type PET / PTT composite fibers. After the PET and PTT components are spun through a composite assembly, the pre-network uses an asymmetric network structure. Because PTT fibers are relatively soft, if a traditional single-outlet network is used, the PTT fibers are prone to friction with the upper and lower guide ceramic parts and the pre-network, resulting in fuzzing. However, PET fibers are rigid and less prone to fuzzing. This invention utilizes the airflow generated by the downward-facing pre-network to both facilitate oil penetration and provide downward traction, thus stabilizing the spinning tension. Meanwhile, the airflow generated by the upward-facing pre-network prevents the fiber bundle from rubbing against the ceramic parts, avoiding fuzzing.

[0026] Before subsequent winding, an asymmetric networker is used for the main network. Because PTT fibers are more elastic and have a softer feel, while PET fibers are more rigid and have poor elastic recovery, the asymmetric networker allows the PTT fibers to wrap better around the PET fibers. Specifically, PTT fibers have better elastic recovery and can shrink under network air pressure, while PET fibers are more rigid and have better dimensional stability. The asymmetric network air pressure creates unbalanced stress points, blowing the lighter, more shrinkable PTT fibers to the outside of the bundle, while the PET fibers remain in the middle. Simultaneously, the asymmetric networker also creates tension on the PTT fibers, causing them to wrap around the PET fibers, thus improving the elasticity of the composite fiber.

[0027] Therefore, by employing a special asymmetric network structure design, this invention enables PTT fibers to fully utilize their excellent elastic properties, and by taking advantage of the rigidity of PET fibers in the middle, it solves the problem of balancing fiber elasticity and breaking strength, and effectively avoids the generation of fuzz. The final product has a crimp shrinkage rate ≥45.3%, crimp stability ≥89.9%, breaking strength ≥3.5cN / dtex, and fuzz degradation rate ≤0.8%.

[0028] Beneficial effects:

[0029] The present invention discloses a method for preparing highly crimped parallel PET / PTT composite fibers. It employs a special asymmetric network structure design, which enables PTT fibers to fully utilize their excellent elastic properties and utilizes the rigidity of PET fibers in the middle, thus solving the problem of the difficulty in balancing fiber elasticity and breaking strength. Detailed Implementation

[0030] 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.

[0031] The test methods involved in the performance indicators in the embodiments and comparative examples of this invention are as follows:

[0032] Curl shrinkage rate and curl stability: According to GB / T 6506-2017 "Test Method for Curl Shrinkage Performance of Synthetic Fiber Textured Yarn", the test was conducted using a fully automatic filament curl shrinkage tester (model YG368-III).

[0033] Tensile strength: In accordance with GB / T 14344-2022 "Test Method for Tensile Properties of Chemical Fiber Filaments", the sample was tested using a fully automatic single yarn tensile testing machine (model YG023B-Ⅱ). The specific process was as follows: First, the sample was placed in an environment with a temperature of 20℃ and a relative humidity of 65% for 4 hours to acclimate it. Then, it was clamped by upper and lower clamps (clamping length of 500mm), and a pretension of 0.05cN / dtex was applied by a robotic arm to stabilize the sample. At the start of the test, the lower clamp stretched the sample at a uniform speed of 500mm / min until the sample broke. At the same time, the real-time data of the force sensor was recorded during the stretching process, and the relationship curve between strength and elongation was plotted through the data collection system. Finally, the tensile strength of the sample was obtained through data processing and analysis.

[0034] Network density: According to the standard "Test Method for Network Degree of Synthetic Fiber Filaments" (FZ / T 50001-2016), the method D water bath needle transfer method was used for testing.

[0035] Downgrading rate of filaments: filaments are downgraded if there are more than 10 single filament breakage defects on the surface of each filament roll. Downgrading rate of filaments = number of downgraded filaments × 100% / total number of filaments.

[0036] Example 1

[0037] A method for preparing highly crimped side-by-side PET / PTT composite fibers, the specific process of which is as follows:

[0038] PET chips (manufacturer: Zhejiang Hengtong Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.625 dL / g) and PTT chips (manufacturer: Zhejiang Hengchao Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.915 dL / g) are crystallized and dried, melt extruded, filtered and metered, and then combined. The resulting composite fiber is produced through a process of spinning with composite components → cooling → oiling → pre-networking → first hot roller group → second hot roller group → guide roller → main network → winding. The resulting high-cribability side-by-side PET / PTT composite fiber has a specification of 55 dtex / 36f. The mass ratio of PET chips to PTT chips is 52:48.

[0039] Both the pre-network and the main network use networkers that contain two nozzles arranged vertically.

[0040] The pre-network and main network use a networker with a length of 6cm, a nozzle diameter of 2mm, and a distance of 2cm between the upper and lower nozzles;

[0041] In the pre-network device, the nozzle of the upper nozzle is tilted at 25° downwards and the nozzle of the lower nozzle is tilted at 30° upwards; the pressure of the upper nozzle is 0.05 MPa and the pressure of the lower nozzle is 0.03 MPa.

[0042] In the network device used in the main network, the nozzle of the upper nozzle is tilted 60° downwards to spray air, and the nozzle of the lower nozzle is tilted 45° upwards to spray air; the air pressure of the upper nozzle is 0.3MPa, and the air pressure of the lower nozzle is 0.2MPa.

[0043] The PET spinning temperature is 270℃, the PTT spinning temperature is 258℃, the cooling temperature is 21℃, the oiling rate is 0.95%, the speed of the first hot roller group is 1800m / min, and the temperature is 78℃; the speed of the second hot roller group is 4100m / min, and the temperature is 160℃; the guide roller speed is 4080m / min; and the winding speed is 4080m / min.

[0044] The final high-crimp parallel PET / PTT composite fiber had a crimp shrinkage rate of 45.9%, a crimp stability of 89.9%, a breaking strength of 3.54 cN / dtex, a network density of 17 fibers / meter, and a filament degradation rate of 0.74%.

[0045] Comparative Example 1

[0046] A method for preparing parallel PET / PTT composite fibers is basically the same as in Example 1, except that in the networkers used for the pre-network and main network, the nozzles of the upper and lower nozzles are not tilted, but are set perpendicular to the fiber bundle.

[0047] The final parallel PET / PTT composite fiber had a network density of 13 fibers / meter and a fiber degradation rate of 0.96%.

[0048] Comparing Comparative Example 1 and Example 1, it can be observed that the network density decreases while the fuzz reduction rate increases. This is because the air pressure in the networker is blown vertically towards the filament bundle, which only blows the entire filament bundle away from the network nozzle, preventing the network air pressure from rotating and intersecting between the filament bundles to create network points, thus leading to a decrease in the number of network density points. At the same time, blowing vertically towards the filament bundle causes significant vibration of the filament bundle, resulting in friction between the filament bundle and the ceramic part, generating fuzz, and therefore increasing the fuzz reduction rate.

[0049] Comparative Example 2

[0050] A method for preparing a parallel PET / PTT composite fiber is basically the same as in Example 1, except that the networker used in the pre-network is a conventional networker (TMT-2414) of the prior art.

[0051] The final grade of the side-by-side PET / PTT composite fiber was 0.83%.

[0052] Comparing Comparative Example 2 and Example 1, it can be found that the fuzz reduction rate increases. This is because the pre-network device of Comparative Example 2 only has one pre-network nozzle, which cannot offset the tension fluctuations from spinning, tunnel and winding, resulting in fuzz generated by the friction between PTT fibers and ceramic parts, thus increasing the fuzz reduction rate.

[0053] Comparative Example 3

[0054] A method for preparing a parallel PET / PTT composite fiber is basically the same as in Example 1, except that the main network uses a conventional networker (Hibernate HN-133A).

[0055] The final side-by-side PET / PTT composite fiber had a crimp shrinkage rate of 40.6%, a crimp stability of 86.4%, and a network density of 16 cells / meter.

[0056] Comparing Comparative Example 3 and Example 1, it can be observed that the crimping shrinkage rate, crimping stability, and network density are reduced. This is because a conventional networker has only one nozzle, and under high-pressure network air pressure, it cannot achieve a sufficient amount of PTT fibers winding around the PET fibers. Since the elasticity and shrinkage rate of PTT fibers are much higher than those of PET fibers, this results in low crimping shrinkage rate and crimping stability of the bicomponent composite fibers. Simultaneously, because there is only one network nozzle, the impact and entanglement effect of the airflow on the fiber bundle are weakened, thus reducing the network density.

[0057] Comparative Example 4

[0058] A method for preparing a parallel PET / PTT composite fiber is basically the same as in Example 1, except that in the pre-networking device, the pressure of the upper nozzle is 0.08 MPa and the pressure of the lower nozzle is 0.05 MPa.

[0059] The final side-by-side PET / PTT composite fiber had a crimp shrinkage rate of 44.2%, a crimp stability of 87.4%, and a fuzz downgrade rate of 0.82%.

[0060] Comparing Comparative Example 4 and Example 1, it can be found that the crimping shrinkage rate and crimping stability are reduced, while the fuzzing degradation rate is increased. This is because the pre-network air pressure is higher, which easily forms network nodes, resulting in "local" insufficient heating when the composite fiber is heated by the hot roller, affecting its relaxation effect, that is, inhibiting the crimping and shrinkage of PTT fibers, and ultimately affecting the elasticity and crimping shrinkage of the composite fiber. The higher pre-network air pressure also causes the PTT fibers with better elasticity and shrinkage to rub against the ceramic parts, which in turn leads to an increase in fuzzing degradation.

[0061] Comparative Example 5

[0062] A method for preparing parallel PET / PTT composite fibers is basically the same as in Example 1, except that in the pre-networking device, the pressure of the upper nozzle is 0.04 MPa and the pressure of the lower nozzle is 0.02 MPa.

[0063] The final grade of the side-by-side PET / PTT composite fiber had a downgrade rate of 0.87%.

[0064] Comparing Comparative Example 5 and Example 1, it can be observed that the rate of fuzz downgrading increases. This is because the pre-networker blows air onto the fiber bundle in a crisscross pattern from top to bottom. The lower pre-network air pressure causes the vertical forces between the airflow and the fiber bundle to cancel each other out, creating a "static pressure zone" in the fiber bundle between the two nozzles. This affects the oil permeability of the fibers, leading to uneven oiling and increased friction, thus increasing the number of fuzz downgrading fibers. Simultaneously, the lower pre-network air pressure causes PTT fibers to easily deviate from the center of the pre-networker, resulting in fuzzing.

[0065] Comparative Example 6

[0066] A method for preparing a parallel PET / PTT composite fiber is basically the same as in Example 1, except that the pressure of the upper nozzle in the main network is 0.28 MPa and the pressure of the lower nozzle is 0.18 MPa.

[0067] The final side-by-side PET / PTT composite fiber had a crimp shrinkage rate of 43.6%, a crimp stability of 87.3%, and a network density of 15 fibers / meter.

[0068] Comparing Comparative Example 6 and Example 1, it can be found that the crimping shrinkage rate, crimping stability, and network density are reduced. This is because the airflow in the networker is insufficient, which makes it impossible to form network nodes and blow the lighter and more shrinkable PTT fibers to the outside of the filament bundle. As a result, the spiral crimping structure of the PET / PTT composite fiber is more disordered, thus reducing the crimping shrinkage rate and crimping stability. At the same time, the main network air pressure is low, that is, the impact force of the airflow on the filament bundle is small, which cannot overcome the tension between the filament bundles to form nodes, thus reducing the network density.

[0069] Comparative Example 7

[0070] A method for preparing a parallel PET / PTT composite fiber is basically the same as in Example 1, except that the pressure of the upper nozzle in the main network is 0.42 MPa and the pressure of the lower nozzle is 0.28 MPa.

[0071] The final parallel PET / PTT composite fiber had a network density of 29 fibers / meter and a fiber degradation rate of 0.89%.

[0072] Comparing Comparative Example 7 and Example 1, it can be observed that the network density and the rate of fuzz reduction increase. This is because excessive airflow pressure within the networker easily leads to overly dense network points in the fibers, resulting in a higher network density. An excessively high network density reduces the bulkiness of the composite fibers and worsens their softness. Simultaneously, the higher airflow pressure from the lower nozzle creates a greater resistance, opposing the weight and traction of the fiber bundle, which easily leads to unstable tension and thus increases the rate of fuzz reduction.

[0073] Comparative Example 8

[0074] A method for preparing a parallel PET / PTT composite fiber is basically the same as in Example 1, except that during the pre-networking process, the pressure of the air jet from the lower nozzle is adjusted to the pressure of the air jet from the upper nozzle, i.e., 0.05 MPa.

[0075] The final grade of the side-by-side PET / PTT composite fiber was 0.85%.

[0076] Comparing Comparative Example 8 and Example 1, it can be observed that the downgrading rate of fuzz increases. This is because the air pressure from the lower nozzle is equal to that from the upper nozzle. Since the airflow is directed at the filament bundle from both above and below, the vertical force between the airflow and the filament bundle cancels out, resulting in a "static pressure zone" in the filament bundle between the two nozzles. This affects the oil permeability of the composite fiber, thus increasing the downgrading rate of fuzz. Furthermore, the high air pressure in the lower pre-networking section makes it easier to blow PTT fibers away from the center of the pre-networker, which also leads to an increase in the number of downgraded fuzz fibers.

[0077] Comparative Example 9

[0078] A method for preparing parallel PET / PTT composite fibers is basically the same as in Example 1, except that: during the main network preparation, the pressure of the air jet from the lower nozzle is adjusted to the pressure of the air jet from the upper nozzle, i.e., 0.3 MPa.

[0079] The final parallel PET / PTT composite fiber had a downgrade rate of 0.89% and a network density of 14 fibers / meter.

[0080] Comparing Comparative Example 9 and Example 1, it can be observed that the filament degradation rate increases. This is because the air pressure from the lower nozzle is higher, which means the upward airflow creates greater resistance opposite to the weight and traction of the filament bundle, easily leading to tension instability and thus increasing the filament degradation rate. Simultaneously, the air pressure from the lower nozzle is equal to that from the upper nozzle, and the nozzle distance differs by 2 cm. Because the airflow is blown onto the filament bundle in a crisscross pattern, the vertical force between the airflow and the filament bundle cancels out, resulting in a "static pressure zone" in the filament bundle between the two nozzles. This causes the fiber network density to be uneven, with one section having more fiber and the other less, resulting in poor and uneven network performance.

[0081] Example 2

[0082] A method for preparing highly crimped side-by-side PET / PTT composite fibers, the specific process of which is as follows:

[0083] PET chips (manufacturer: Zhejiang Hengtong Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.628 dL / g) and PTT chips (manufacturer: Zhejiang Hengchao Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.920 dL / g) are crystallized and dried, melt extruded, filtered and metered, and then combined. The resulting composite fiber is produced through a process of spinning with composite components → cooling → oiling → pre-networking → first hot roller group → second hot roller group → guide roller → main network → winding. The resulting high-cribability side-by-side PET / PTT composite fiber has a specification of 55 dtex / 32f. The mass ratio of PET chips to PTT chips is 45:55.

[0084] Both the pre-network and the main network use networkers that contain two nozzles arranged vertically.

[0085] The pre-network and main network use a network device with a length of 6.5cm, a nozzle diameter of 2.5mm, and a distance of 2.5cm between the upper and lower nozzles;

[0086] In the pre-network device, the nozzle of the upper nozzle is tilted at 28° downwards and the nozzle of the lower nozzle is tilted at 32° upwards; the pressure of the upper nozzle is 0.06 MPa and the pressure of the lower nozzle is 0.035 MPa.

[0087] In the network device used in the main network, the nozzle of the upper nozzle is tilted at 55° downwards and the nozzle of the lower nozzle is tilted at 40° upwards; the pressure of the upper nozzle is 0.32 MPa and the pressure of the lower nozzle is 0.21 MPa.

[0088] The PET spinning temperature is 272℃, the PTT spinning temperature is 260℃, the cooling temperature is 22℃, the oiling rate is 1.05%, the speed of the first hot roller group is 1900m / min, and the temperature is 79℃; the speed of the second hot roller group is 4125m / min, and the temperature is 162℃; the guide roller speed is 4100m / min; and the winding speed is 4100m / min.

[0089] The final high-crimp parallel PET / PTT composite fiber had a crimp shrinkage rate of 49.4%, a crimp stability of 93.2%, a breaking strength of 3.59 cN / dtex, a network density of 19 fibers / meter, and a filament degradation rate of 0.69%.

[0090] Example 3

[0091] A method for preparing highly crimped side-by-side PET / PTT composite fibers, the specific process of which is as follows:

[0092] PET chips (manufacturer: Zhejiang Hengtong Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.630 dL / g) and PTT chips (manufacturer: Zhejiang Hengchao Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.923 dL / g) were crystallized and dried, melt extruded, filtered and metered, and then combined. The resulting composite fiber was produced through a process of spinning with composite components → cooling → oiling → pre-networking → first hot roller group → second hot roller group → guide roller → main network → winding. This process yielded a high-crib, side-by-side PET / PTT composite fiber with a specification of 55 dtex / 36f. The mass ratio of PET chips to PTT chips was 51:49.

[0093] Both the pre-network and the main network use networkers that contain two nozzles arranged vertically.

[0094] The pre-network and main network use a networker with a length of 7cm, a nozzle diameter of 3mm, and a distance of 3cm between the upper and lower nozzles;

[0095] In the pre-network device, the nozzle of the upper nozzle is tilted 30° downwards and the nozzle of the lower nozzle is tilted 35° upwards; the pressure of the upper nozzle is 0.07 MPa and the pressure of the lower nozzle is 0.04 MPa.

[0096] In the main network device, the nozzle of the upper nozzle is tilted at 55° downwards and the nozzle of the lower nozzle is tilted at 35° upwards; the pressure of the upper nozzle is 0.35 MPa and the pressure of the lower nozzle is 0.22 MPa.

[0097] The PET spinning temperature is 274℃, the PTT spinning temperature is 262℃, the cooling temperature is 21.5℃, the oiling rate is 1%, the speed of the first hot roller group is 1950m / min, and the temperature is 80℃; the speed of the second hot roller group is 4170m / min, and the temperature is 165℃; the guide roller speed is 4150m / min; and the winding speed is 4150m / min.

[0098] The final high-crimp parallel PET / PTT composite fiber had a crimp shrinkage rate of 46.2%, a crimp stability of 91.3%, a breaking strength of 3.5 cN / dtex, a network density of 20 fibers / meter, and a filament degradation rate of 0.64%.

[0099] Example 4

[0100] A method for preparing highly crimped side-by-side PET / PTT composite fibers, the specific process of which is as follows:

[0101] PET chips (manufacturer: Zhejiang Hengtong Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.633 dL / g) and PTT chips (manufacturer: Zhejiang Hengchao Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.922 dL / g) were crystallized and dried, melt extruded, filtered and metered, and then combined. The resulting composite fiber was produced through a process of spinning with composite components → cooling → oiling → pre-networking → first hot roller group → second hot roller group → guide roller → main network → winding. This process yielded a high-crib, side-by-side PET / PTT composite fiber with a specification of 55 dtex / 36f. The mass ratio of PET chips to PTT chips was 48:52.

[0102] Both the pre-network and the main network use networkers that contain two nozzles arranged vertically.

[0103] The pre-network and main network use networkers with a length of 7.5cm, a nozzle diameter of 3mm, and a distance of 2.5cm between the upper and lower nozzles;

[0104] In the pre-network device, the nozzle of the upper nozzle is tilted 32° downwards to spray air, and the nozzle of the lower nozzle is tilted 38° upwards to spray air.

[0105] The pressure of the air jet from the upper nozzle is 0.07 MPa, and the pressure of the air jet from the lower nozzle is 0.04 MPa.

[0106] In the main network device, the nozzle of the upper nozzle is tilted at 55° downwards and the nozzle of the lower nozzle is tilted at 35° upwards; the pressure of the upper nozzle is 0.36 MPa and the pressure of the lower nozzle is 0.23 MPa.

[0107] The PET spinning temperature is 272℃, the PTT spinning temperature is 259℃, the cooling temperature is 21.5℃, the oiling rate is 0.96%, the speed of the first hot roller group is 2000m / min, and the temperature is 81℃; the speed of the second hot roller group is 4215m / min, and the temperature is 167℃; the guide roller speed is 4200m / min; and the winding speed is 4200m / min.

[0108] The final high-crimp parallel PET / PTT composite fiber had a crimp shrinkage rate of 48.3%, a crimp stability of 91.9%, a breaking strength of 3.61 cN / dtex, a network density of 21 fibers / meter, and a filament degradation rate of 0.61%.

[0109] Example 5

[0110] A method for preparing highly crimped side-by-side PET / PTT composite fibers, the specific process of which is as follows:

[0111] PET chips (manufacturer: Zhejiang Hengtong Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.635 dL / g) and PTT chips (manufacturer: Zhejiang Hengchao Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.925 dL / g) are crystallized and dried, melt extruded, filtered and metered, and then combined. The resulting composite fiber is produced through a process of spinning with composite components → cooling → oiling → pre-networking → first hot roller group → second hot roller group → guide roller → main network → winding. This process yields a high-crib, side-by-side PET / PTT composite fiber with a specification of 55 dtex / 32f. The mass ratio of PET chips to PTT chips is 55:45.

[0112] Both the pre-network and the main network use networkers that contain two nozzles arranged vertically.

[0113] The pre-network and main network use networkers with a length of 8cm, a nozzle diameter of 2.5mm, and a distance of 3cm between the upper and lower nozzles;

[0114] In the pre-network device, the nozzle of the upper nozzle is tilted at 34° downwards and the nozzle of the lower nozzle is tilted at 40° upwards; the pressure of the upper nozzle is 0.06 MPa and the pressure of the lower nozzle is 0.035 MPa.

[0115] In the network device used in the main network, the nozzle of the upper nozzle is tilted 50° downwards to spray air, and the nozzle of the lower nozzle is tilted 30° upwards to spray air.

[0116] The pressure of the air jet from the upper nozzle is 0.38 MPa, and the pressure of the air jet from the lower nozzle is 0.24 MPa.

[0117] The PET spinning temperature is 273℃, the PTT spinning temperature is 260℃, the cooling temperature is 21℃, the oiling rate is 0.98%, the speed of the first hot roller group is 2050m / min, and the temperature is 82℃; the speed of the second hot roller group is 4270m / min, and the temperature is 168℃; the guide roller speed is 4250m / min; and the winding speed is 4250m / min.

[0118] The final high-crimp parallel PET / PTT composite fiber had a crimp shrinkage rate of 45.3%, a crimp stability of 91%, a breaking strength of 3.52 cN / dtex, a network density of 22 fibers / meter, and a filament degradation rate of 0.56%.

[0119] Example 6

[0120] A method for preparing highly crimped side-by-side PET / PTT composite fibers, the specific process of which is as follows:

[0121] PET chips (manufacturer: Zhejiang Hengtong Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.630 dL / g) and PTT chips (manufacturer: Zhejiang Hengchao Chemical Fiber Co., Ltd., Tongkun Group, semi-dull chips, intrinsic viscosity of 0.920 dL / g) were crystallized and dried, melt extruded, filtered and metered, and then combined. The resulting composite fiber was produced through a process of spinning with composite components → cooling → oiling → pre-networking → first hot roller group → second hot roller group → guide roller → main network → winding. This process yielded a high-crib, side-by-side PET / PTT composite fiber with a specification of 55 dtex / 36f. The mass ratio of PET chips to PTT chips was 53:47.

[0122] Both the pre-network and the main network use networkers that contain two nozzles arranged vertically.

[0123] The pre-network and main network use networkers with a length of 7.5cm, a nozzle diameter of 2mm, and a distance of 3cm between the upper and lower nozzles;

[0124] In the pre-network device, the nozzle of the upper nozzle is tilted at 35° downwards and the nozzle of the lower nozzle is tilted at 45° upwards; the pressure of the upper nozzle is 0.05 MPa and the pressure of the lower nozzle is 0.03 MPa.

[0125] In the network device used in the main network, the nozzle of the upper nozzle is tilted at 45° downwards and the nozzle of the lower nozzle is tilted at 30° upwards; the pressure of the upper nozzle is 0.4MPa and the pressure of the lower nozzle is 0.25MPa.

[0126] The PET spinning temperature is 272℃, the PTT spinning temperature is 260℃, the cooling temperature is 21℃, the oiling rate is 0.99%, the speed of the first hot roller group is 2030m / min, and the temperature is 78℃; the speed of the second hot roller group is 4200m / min, and the temperature is 170℃; the guide roller speed is 4180m / min; and the winding speed is 4180m / min.

[0127] The final high-crimp parallel PET / PTT composite fiber had a crimp shrinkage rate of 46.4%, a crimp stability of 90.7%, a breaking strength of 3.58 cN / dtex, a network density of 23 fibers / meter, and a filament degradation rate of 0.54%.

Claims

1. A method for preparing highly crimped side-by-side PET / PTT composite fibers, characterized in that: PET chips and PTT chips are crystallized and dried, melt extruded, filtered and metered respectively, then combined and then processed through a composite component spinning → cooling → oiling → pre-networking → first hot roller group → second hot roller group → guide roller → main network → winding to obtain high crimp side-by-side PET / PTT composite fiber. Both the pre-network and the main network use networkers that contain two nozzles arranged vertically; the nozzle above sprays air downwards at an angle, while the nozzle below sprays air upwards at an angle. In the pre-network device, the pressure of the air jet from the upper nozzle is 0.05~0.07MPa, and the pressure of the air jet from the lower nozzle is 0.03~0.04MPa; In the network device used in the main network, the pressure of the upper nozzle is 0.3~0.4MPa, and the pressure of the lower nozzle is 0.2~0.25MPa.

2. The method for preparing a highly crimped side-by-side PET / PTT composite fiber according to claim 1, characterized in that, The pre-network and main network use networkers with a length of 6-8cm, a nozzle diameter of 2-3mm, and a distance of 2-3cm between the upper and lower nozzles.

3. The method for preparing a highly crimped side-by-side PET / PTT composite fiber according to claim 1, characterized in that, In the pre-network device, the nozzle of the upper nozzle is tilted at 25°~35° to spray air downwards, and the nozzle of the lower nozzle is tilted at 30°~45° to spray air upwards.

4. The method for preparing a highly crimped side-by-side PET / PTT composite fiber according to claim 1, characterized in that, In the main network, the nozzle of the upper nozzle is tilted at 45°~60° to spray air downwards, while the nozzle of the lower nozzle is tilted at 30°~45° to spray air upwards.

5. The method for preparing a highly crimped side-by-side PET / PTT composite fiber according to claim 1, characterized in that, The mass ratio of PET slices to PTT slices is 45~55:55~45.

6. The method for preparing a highly crimped side-by-side PET / PTT composite fiber according to claim 1, characterized in that, The speed of the first hot roller group is 1800~2050m / min, and the temperature is 78~82℃; the speed of the second hot roller group is 4100~4270m / min, and the temperature is 160~170℃; the guide roller speed is 4080~4250m / min; and the winding speed is 4080~4250m / min.

7. The method for preparing a highly crimped side-by-side PET / PTT composite fiber according to claim 1, characterized in that, The crimp shrinkage rate of the high crimp parallel PET / PTT composite fiber is ≥45.3%, the crimp stability is ≥89.9%, the breaking strength is ≥3.5cN / dtex, the network density is 20±3 / cell / meter, and the filament degradation rate is ≤0.8%.