An elastic fiber with a draping feeling and a cotton feeling and a preparation method thereof

Abstract

The present invention relates to an elastic fiber with a draping feeling and a cotton feeling and a preparation method thereof. The pre-oriented polyester fiber is made into an elastic fiber with a draping feeling and a cotton feeling through a texturing process. The texturing process flow is: pre-oriented polyester fiber → pre-network → first feed roller → texturing hot box → cooling plate → false twister → second feed roller → auxiliary roller → setting hot box → setting feed roller → oiling roller → DTY winding and forming with overfeed → elastic fiber; the temperature of the texturing hot box is 230 - 250 °C, and the setting hot box is closed; the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.2 - 1.5; the breaking elongation rate of the obtained elastic fiber with a draping feeling and a cotton feeling is 19 - 23%, the crimp shrinkage rate is 8 - 11%, and the draping resilience percentage after the fiber is woven into a fabric is 15 - 26%. The method of the present invention is simple, can meet large-scale development and use; the product has the characteristics of a balance between high drapability and cotton softness.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical fibers, and relates to an elastic fiber with a draping feeling and a cotton feeling and a preparation method thereof. Background Art

[0002] With the continuous progress and innovation of the textile fabric market, the appearance patterns and characteristics of traditional polyester fibers no longer meet the requirements of the fabric and textile markets. Therefore, various differential fibers have been created for use in various fabrics and textiles.

[0003] Currently, there is a stretch cotton and linen blended fabric on the market, which is made by blending stretch yarn with a compound yarn of mulberry silk and linen twisted together. It has the softness and moisture absorption characteristics of cotton fibers, the breathability and luster of linen fibers, and at the same time has the elasticity of stretch yarn.

[0004] Polyester fibers generally have a series of excellent properties such as high breaking strength and elastic modulus, moderate resilience, excellent heat setting, good heat and light resistance, and acid, alkali and corrosion resistance. Moreover, its fabrics have advantages such as wrinkle resistance, non-ironing and good stiffness, and are widely used in the fields of clothing, home textiles, etc. Through equipment and process adjustment, differential fibers with unique appearances and different hand feelings can be produced under the condition of physical properties and weaving stability.

[0005] However, in fabric design, the draping feeling and the cottony soft feeling are two characteristics that are difficult to achieve simultaneously. Currently, the commonly used method to obtain the draping feeling is to use fibers with different elastic moduli and twist degrees, and form a contraction torque through the elastic difference and twist difference to obtain a high draping property of the fabric; the cottony soft feeling of the fabric can be formed by applying air pressure network after secondary stretching. Since uniform stretching will damage the elasticity and twist of the fiber, resulting in the loss of the draping property of the fiber, there is a conflict between the draping property and the cottony soft feeling of the fiber, and it is difficult to achieve a balance.

[0006] In order to make the fabric have both the draping feeling and the cottony soft feeling, two relatively opposite characteristics, the prior art usually uses fibers of multiple different components for compounding. For example, Patent CN202411023018.3 mentions a stretch cottony soft cloth and its production process, which is woven by combining two film layers, one is a non-woven fabric layer and the other is an elastic film layer.

[0007] Patent CN207904452U mentions a stretch cotton, linen and silk blended fabric. The warp yarn is stretch yarn (the inner layer of the stretch yarn is modal fiber and the outer layer is slub cotton), and the weft yarn is a compound yarn formed by twisting mulberry silk and linen together.

[0008] The methods of using fibers of different components for compounding in the prior art mainly have the following disadvantages: (1) high physical property requirements for each raw material and high cost; (2) single composition and inflexible adjustment.

[0009] Therefore, it is of great significance to study an elastic fiber with a draping feeling and a cotton feeling and its preparation method to solve the problems existing in the prior art. Summary of the Invention

[0010] The object of the present invention is to solve the problems existing in the prior art and provide an elastic fiber with a draping feeling and a cotton feeling and its preparation method.

[0011] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0012] A preparation method of an elastic fiber with a draping feeling and a cotton feeling, wherein the pre-oriented polyester fiber is made into an elastic fiber with a draping feeling and a cotton feeling through a texturing process;

[0013] The texturing process flow is: pre-oriented polyester fiber → pre-network → first feed roller → texturing hot box → cooling plate → false twister → second feed roller (W2 roller) → auxiliary roller (W2X roller) → setting hot box → setting feed roller → oiling roller → DTY winding forming with overfeed → elastic fiber; compared with the texturing process flow in the prior art, the present invention does not add a middle network. Adding a middle network will destroy the uneven filament state caused by high temperature and incomplete stretching. The present invention adds a pre-network air pressure before stretching, applies the pre-network air pressure to enhance the filament bunching property and the cottony soft feeling of the product;

[0014] The temperature of the texturing hot box is 230-250 °C. At this temperature, the movement of the macromolecular chains of the polyester fiber is activated, and the movement tends to be disordered. The higher the temperature, the more active the movement of the macromolecular chains, and the easier it is to generate molecular chain adhesion; the setting hot box is closed, that is, the temperature of the setting hot box is normal temperature. The lack of the stress-relieving effect of the setting temperature will enable the fiber to maintain a high elastic modulus and ensure the elastic physical properties of the product; the rotational speed of the second feed roller (i.e., the vehicle speed) is 300-600 m / min, and the ratio of the speed of the second feed roller to the speed of the first feed roller (i.e., the draw ratio) is 1.29-1.5; the draw ratio of conventional fibers is between 1.55 and 1.75. With low draw ratio stretching, the smaller orientation force causes some active macromolecular chain segments not to complete orientation and hook up, and the appearance shows that single filaments adhere to each other to produce thin segments;

[0015] The false-twister is a friction disc type false-twister; both the upper layer inlet disc (functioning as the inlet of the filament) and the lower layer outlet disc (functioning as the outlet of the filament) of the false-twister adopt smooth discs, and the middle layer (functioning as the friction false-twisting) adopts 5 polyurethane friction discs; different from the installation method of the false-twister in the prior art, the lowermost layer in the prior art is a ceramic trapezoidal cutting edge disc. By replacing the ceramic disc in the lowermost layer, the friction damage is reduced, and the thick and thin section structure generated by high temperature and low drawing is retained and a three-dimensional effect is applied; the speed ratio of the false-twister (referring to the ratio of the rotation speed of the false-twister to the rotation speed of the second feeding roller) is 1.5 - 2.13. When the rotation speed of the second feeding roller, that is, the vehicle speed, is determined, the rotation speed of the false-twister is controlled by controlling the speed ratio of the false-twister;

[0016] The overfeed of the auxiliary roller (i.e., the speed difference ratio, and its calculation formula is (the rotation speed of the W2X roller - the rotation speed of the W2 roller) / the rotation speed of the W2 roller) is -24.5% - -16.0%, and the speed of the auxiliary roller is controlled by a frequency conversion device. The frequency of the frequency conversion device includes a low frequency and a high frequency; the low frequency is 10 - 30Hz, and the high frequency is 50 - 90Hz; the frequency of the frequency conversion device changes periodically. Within one cycle, the frequency conversion device is first in the low frequency state and then switches to the high frequency state. The time of one cycle is 10 - 30s; within one cycle, the time when the frequency conversion device is in the low frequency state accounts for 20% - 40% of the time of one cycle, and the switching duration when the frequency conversion device switches from the low frequency state to the high frequency state is 0.5 - 0.8s;

[0017] The change in the rotation speed is mainly generated by the periodically changing set frequency. The basic formula is n = 60f / p, where n is the rotation speed, f is the frequency, and p is the number of pole pairs of the motor rotating magnetic field.

[0018] As a preferred technical solution:

[0019] For the preparation method of an elastic fiber with a draping feeling and a cotton feeling as described above, the pre-network pressure is 0.15 - 0.20MPa, the length of the cooling plate is 1 - 1.5m, the overfeed of the shaping feeding roller is 8.0% - 10.0%, and the overfeed of the winding and forming is 8.0% - 10.0%.

[0020] For the preparation method of an elastic fiber with a draping feeling and a cotton feeling as described above, the texturing process uses a TMT1500 - FOUR automatic doffing single-strand machine, and this machine has the following characteristics: (1) The texturing hot box adopts a trough type diphenyl insulation, and the texturing temperature is stable; (2) An auxiliary roller is added to enhance the stability of the filament bundle before entering the shaping hot box; (3) Automatic doffing is adopted to reduce the labor cost of doffing.

[0021] For the preparation method of an elastic fiber with a draping feeling and a cotton feeling as described above, the fineness of the pre-oriented polyester fiber is 135 - 600 dtex.

[0022] The present invention also provides an elastic fiber with a draping feeling and a cotton feeling, prepared by the preparation method described in any one of the above. It is a pre-oriented polyester fiber. After the internal molecular chain order is damaged due to high temperature, it generates a polyester fiber with uniform thickness segments, cotton softness and elasticity after passing through the roller stretching and twisting processes. The elastic fiber with a draping feeling and a cotton feeling presents a fluffy feather-like appearance with thick segments rebounding and curling, and thin segments are slender with a small twist. The combination of these two characteristics results in a spring-like structure with drapability. The single filament fineness of the elastic fiber with a draping feeling and a cotton feeling is 1.3 - 2.5 dtex, the breaking strength is 2.9 - 3.2 cN / dtex, the breaking elongation is 19 - 23%, the crimp shrinkage rate is 8 - 11%, and the boiling water shrinkage rate is 3.9 - 5.0%. The cotton softness is characterized by the fabric softness, which is reflected in the bending deformation degree of the fabric and can be obtained from the elongation and crimp indexes of the elastic fiber with a draping feeling and a cotton feeling. Among them, the elongation rate reflects the tensile strength of the fiber monomer and the anti-deformation degree of the fabric. The greater the elongation, the greater the elongation of the fiber, the greater the extrusion and tensile forces that the fiber can bear in the woven fabric, and the faster it returns to stability after being subjected to the deformation force, and the stronger the cotton softness of the overall fabric. The crimp shrinkage stability index reflects the uniform degree of shrinkage and bending deformation of each unit fiber, and in terms of the fabric, it reflects the uniform degree of compression deformation of each unit fabric. The better the stability, the better the softness and uniformity of the overall fabric. The drapability is reflected in that when the fabric is hung, the fabric surface will have a regular percentage of rebound due to the draping characteristics. The strength of the fabric's draping feeling is reflected in the percentage of rebound of the fabric. The draping and rebound percentage of the elastic fiber with a draping feeling and a cotton feeling woven into a fabric is 15 - 26%.

[0023] Principle of the invention:

[0024] The draping feeling and the cotton softness are two relatively opposite characteristics. To make the fabric have both characteristics at the same time, the prior art usually uses fibers with multiple different components for compounding. The present invention creatively proposes a preparation method for an elastic fiber with a draping feeling and a cotton feeling. By first unstably stretching the fiber to obtain a fiber structure with different thicknesses, and through subsequent equipment transformation and process debugging, uniformly stretching to destroy a certain amount of the thin segment structure, the thick segment structure fiber obtains a high twist due to the false twist effect and retracts through a low hot box temperature to form a certain cotton softness. In this way, a polyester fiber with a balance between the two is obtained.

[0025] At high heat setting temperatures in the hot box, the orderliness of molecular motion within the fiber is disrupted, leading to the development of disorder over a unit distance. A low machine speed ensures that the fiber is fully heated within the high heat setting temperature in the hot box, more effectively disrupting the ordered motion of the molecular chains. The low draft then incompletely stretches the fiber. After the combination of high heat setting temperature and low machine speed, uneven stretching on the fiber surface results in a non-uniform thickness state. By combining the modification of the false twister equipment and the regulation of the false twist speed, the characteristic of non-uniform twist of the fiber can be obtained (in the prior art, the function of the delivery disc of the false twister equipment is to uniformly reduce the twist of the fiber after continuous false twisting through each friction disc of the false twister. In the present invention, through equipment modification and replacement of the delivery disc structure, the twist reduction effect is decreased, and a non-uniform twist reduction effect can be obtained; for fibers of different specifications and varieties, different speed ratios need to be set). The fiber obtains high drapability. The auxiliary roller is equipped with a frequency converter, and under the stretching at a certain frequency speed, the fiber regularly produces a certain amount of untwisting effect, and the untwisted part of the fiber generates elasticity and a cottony soft feeling (the set value of the frequency conversion device is specified as "low speed duration - high speed duration", and by adjusting the time of high frequency and low frequency within a certain period, the magnitude and frequency of the stretching force on the fiber are controlled, thereby achieving regular stretching and obtaining the required product characteristics. The faster the proportion of high speed frequency, the more sufficient the stretching and the stronger the cottony soft feeling; conversely, if the proportion of low speed frequency is fast, the cottony soft feeling will be weakened). With different process settings, the frequency conversion of the auxiliary roller, and the speed of the false twister, the prominence of the drapability and the cottony soft feeling will vary slightly. The product prepared by the method of the present invention has the characteristics of a balance between high drapability and cottony soft feeling.

[0026] Advantages:

[0027] (1) A method for preparing an elastic fiber with drapability and cottony feeling according to the present invention first obtains a fiber structure with different thicknesses by unstably stretching the fiber. Through subsequent equipment modification and process debugging, a certain amount of the thin segment structure is uniformly stretched and damaged. The fiber of the thick segment structure obtains a high twist due to the false twist effect and retracts through the low heat setting temperature in the hot box to form a certain cottony softness, obtaining a fiber with a balance between high drapability and cottony feeling, which can be widely used in the development and use of different functional fabrics in the market; at the same time, the equipment modification and process physical properties of the present invention can meet mass production and use.

[0028] (2) A method for preparing an elastic fiber with drapability and cottony feeling according to the present invention results in fibers with stable physical properties, and the fiber fineness (mass per unit length) can be adjusted according to the raw materials, being flexible and variable; the product also has the physical properties required for fabrics and has no special requirements for weaving.

[0029] (3) An elastic fiber with drapability and cottony feeling according to the present invention has the same drapability and cottony feeling as the elastic cotton linen silk prepared by twisting elastic fiber and mulberry silk flax on the market. The physical property indexes of the strength, crimp shrinkage, and boiling water shrinkage of the produced fiber can meet the requirements of post-weaving for the cottony feeling and drapability of the fabric. Description of the Drawings

[0030] Figure 1 It is a process flow chart of a texturing process for elastic fibers of the present invention;

[0031] Figure 2 It is a schematic diagram of the false twister disc combination;

[0032] Figure 3 It is the structural characteristics of elastic fibers with drapability and cotton feel;

[0033] Among them, 1 - pre - oriented polyester fiber, 2 - pre - network, 3 - first feed roller, 4 - first texturing hot box, 5 - cooling plate, 6 - false twister, 7 - second feed roller, 8 - auxiliary roller, 9 - second setting hot box, 10 - setting feed roller, 11 - oiling roller, 12 - DTY winding forming overfeed, 13 - upper layer guiding disc, 14 - lower layer discharging disc. Detailed Embodiments

[0034] The present invention will be further described below in conjunction with the detailed embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0035] The test methods for the performance indicators in the embodiments and comparative examples of the present invention are as follows:

[0036] Tensile strength and elongation at break: Execute according to GB / T14344 - 2022.

[0037] Crimp shrinkage rate: Execute according to GBT / 6506 - 2017.

[0038] Boiling water shrinkage rate: Execute according to GBT / 6505 - 2017.

[0039] Drapability rebound percentage: When testing, use a tensile testing machine (universal tensile testing machine). First, vertically suspend the fabric and stretch it to a certain length, then release the tension and record the rebound length; Rebound percentage = (rebound length / stretch length) * 100%.

[0040] Example 1

[0041] A preparation method of elastic fibers with drapability and cotton feel is as follows:

[0042] Pre - oriented polyester fibers with a specification of 266 dtex / 144 f are made into elastic fibers with drapability and cotton feel through a texturing process;

[0043] The texturing process uses a TMT1500 - FOUR automatic doffing single - strand machine, as Figure 1 shown. The texturing process flow is: pre - oriented polyester fiber 1 → pre - network 2 → first feed roller 3 → first texturing hot box 4 → cooling plate 5 → false - twister 6 → second feed roller 7 → auxiliary roller 8 → second setting hot box 9 → setting feed roller 10 → oiling roller 11 → DTY winding forming overfeed 12 → elastic fiber;

[0044] As Figure 2 shown, the false - twister is a friction - disk type false - twister; both the upper inlet disk and the lower outlet disk of the false - twister are smooth disks, and the middle layer uses 5 polyurethane friction disks;

[0045] The pre - network pressure is 0.17 MPa, the length of the cooling plate is 1.5 m, the speed ratio of the false - twister is 1.5, the temperature of the texturing hot box is 230 °C, the setting hot box is closed, the rotational speed of the second feed roller is 350 m / min, the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.3, the overfeed of the setting feed roller is 9%, and the overfeed of the winding forming is 8%;

[0046] The overfeed of the auxiliary roller is - 22.5%, the speed of the auxiliary roller is controlled by a frequency - conversion device, and the frequency of the frequency - conversion device includes a low frequency and a high frequency; the low frequency is 15 Hz, and the high frequency is 55 Hz; the frequency of the frequency - conversion device changes periodically. Within one cycle, the frequency - conversion device is first in the low - frequency state and then switches to the high - frequency state. The time of one cycle is 10 s; within one cycle, the time when the frequency - conversion device is in the low - frequency state accounts for 30% of the time of one cycle.

[0047] As Figure 3 shown, the unit structure of the finally prepared elastic fiber with drapability and cotton - like feel is combined by a thin section and a thick - section fiber with upper and lower resilience.

[0048] The single - filament fineness of the elastic fiber with drapability and cotton - like feel is 1.85 dtex, the breaking strength is 3.09 cN / dtex, the breaking elongation is 22.62%, the crimp shrinkage rate is 9.52%, and the boiling water shrinkage rate is 4.63%; the drape - resilience percentage of the elastic fiber with drapability and cotton - like feel woven into a fabric is 23%.

[0049] Comparative Example 1

[0050] A preparation method of an elastic fiber is basically the same as that of Example 1, except that: the temperature of the texturing hot box is 225 °C.

[0051] The fineness of the single filament of the finally obtained elastic fiber is 1.91 dtex, the breaking strength is 3.11 cN / dtex, the breaking elongation is 23.50%, the crimp shrinkage rate is 10.23%, and the boiling water shrinkage rate is 4.25%; the pendulum rebound percentage after the elastic fiber is woven into a fabric is 13.5%.

[0052] Comparing Comparative Example 1 with Example 1, it can be found that the pendulum resilience of the fiber prepared in Comparative Example 1 is significantly reduced. This is because the decrease in the deformation temperature results in a decrease in the high-temperature destruction effect of the molecular chain, and the molecular chain tends to move stably. Although the cottony softness is enhanced, the pendulum feeling is severely weakened, and the balance between high pendulum property and cottony softness cannot be achieved.

[0053] Comparative Example 2

[0054] A method for preparing an elastic fiber is basically the same as that in Example 1, except that the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.55.

[0055] The fineness of the single filament of the finally obtained elastic fiber is 1.78 dtex, the breaking strength is 3.18 cN / dtex, the breaking elongation is 23.7%, the crimp shrinkage rate is 9.89%, and the boiling water shrinkage rate is 4.32%; the pendulum rebound percentage after the elastic fiber is woven into a fabric is 14.8%.

[0056] Comparing Comparative Example 2 with Example 1, it can be found that the pendulum resilience of the fiber prepared in Comparative Example 2 is significantly reduced. This is because the greater the ratio of the speed of the second feed roller to the speed of the first feed roller, the greater the tensile force on the fiber; the number of thin segments of the fiber decreases and the number of thick segments increases. Due to the decrease in the thin segments, the pendulum feeling is greatly weakened, and the balance between high pendulum property and cottony softness cannot be achieved.

[0057] Comparative Example 3

[0058] A method for preparing an elastic fiber is basically the same as that in Example 1, except that a frequency conversion device is not installed and controlled at the auxiliary feed roller.

[0059] The fineness of the single filament of the finally obtained elastic fiber is 1.85 dtex, the breaking strength is 2.98 cN / dtex, the breaking elongation is 18.74%, the crimp shrinkage rate is 8.7%, and the boiling water shrinkage rate is 4.50%; the pendulum rebound percentage after the elastic fiber is woven into a fabric is 13.27%.

[0060] Comparing Comparative Example 3 with Example 1, it can be found that both the overall elongation and the fabric pendulum percentage of Comparative Example 1 decrease. This is because the lack of regular stretching cannot result in a periodic thick-thin segment structure, and the overall pendulum feeling and cottony softness are uneven, resulting in the simultaneous decrease of the physical property indexes of elongation and fabric pendulum percentage.

[0061] Example 2

[0062] A preparation method of an elastic fiber with a draping feeling and a cotton feeling is as follows:

[0063] The pre-oriented polyester fiber with a specification of 136 dtex / 72 f is made into an elastic fiber with a draping feeling and a cotton feeling through a texturing process;

[0064] The texturing process uses a TMT1500 - FOUR automatic doffing single-strand machine. The texturing process flow is: pre-oriented polyester fiber → pre-network → first feed roller → draw texturing heater → cooling plate → false twister → second feed roller → auxiliary roller → setting heater → setting feed roller → oiling roller → DTY winding forming overfeed → elastic fiber;

[0065] The false twister is a friction disc type false twister; both the upper layer inlet disc and the lower layer outlet disc of the false twister use smooth discs, and the middle layer uses 5 polyurethane friction discs;

[0066] The pre-network pressure is 0.15 MPa, the length of the cooling plate is 1.5 m, the speed ratio of the false twister is 1.72, the temperature of the draw texturing heater is 245 °C, the setting heater is closed, the rotational speed of the second feed roller is 580 m / min, the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.49, the overfeed of the setting feed roller is 8%, and the overfeed of the winding forming is 8.5%;

[0067] The overfeed of the auxiliary roller is -16%, the speed of the auxiliary roller is controlled by a frequency conversion device, and the frequency of the frequency conversion device includes a low frequency and a high frequency; the low frequency is 30 Hz, and the high frequency is 80 Hz; the frequency of the frequency conversion device changes periodically. Within one cycle, the frequency conversion device is first in the low frequency state and then switches to the high frequency state. The time of one cycle is 30 s; within one cycle, the time that the frequency conversion device is in the low frequency state accounts for 34% of the time of one cycle.

[0068] The fineness of the single filament of the finally obtained elastic fiber with a draping feeling and a cotton feeling is 1.89 dtex, the breaking strength is 3.12 cN / dtex, the breaking elongation is 22.36%, the crimp shrinkage rate is 8.84%, and the boiling water shrinkage rate is 4.53%; the draping resilience percentage of the elastic fiber with a draping feeling and a cotton feeling woven into a fabric is 24%.

[0069] Example 3

[0070] A preparation method of an elastic fiber with a draping feeling and a cotton feeling is as follows:

[0071] The pre-oriented polyester fiber with a specification of 540 dtex / 288 f is made into an elastic fiber with a draping feeling and a cotton feeling through a texturing process;

[0072] The texturing process uses a TMT1500 - FOUR automatic doffing single - strand machine. The texturing process flow is: pre - oriented polyester fiber → pre - network → first feed roller → draw - texturing hot box → cooling plate → false - twister → second feed roller → auxiliary roller → setting hot box → setting feed roller → oiling roller → DTY winding and forming overfeed → elastic fiber;

[0073] The false - twister is a friction - disc type false - twister; both the upper inlet disc and the lower outlet disc of the false - twister are smooth discs, and the middle layer uses 5 polyurethane friction discs;

[0074] The pre - network pressure is 0.20 MPa, the length of the cooling plate is 1.5 m, the speed ratio of the false - twister is 1.7, the temperature of the draw - texturing hot box is 247 °C, the setting hot box is closed, the rotational speed of the second feed roller is 300 m / min, the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.29, the overfeed of the setting feed roller is 9.5%, and the overfeed of the winding and forming is 10%;

[0075] The overfeed of the auxiliary roller is - 18%. The speed of the auxiliary roller is controlled by a frequency - conversion device. The frequency of the frequency - conversion device includes a low frequency and a high frequency; the low frequency is 10 Hz, and the high frequency is 70 Hz; the frequency of the frequency - conversion device changes periodically. Within one cycle, the frequency - conversion device first operates in the low - frequency state and then switches to the high - frequency state. The time of one cycle is 20 s; within one cycle, the time when the frequency - conversion device is in the low - frequency state accounts for 24% of the time of one cycle.

[0076] The single - filament fineness of the finally obtained elastic fiber with drape and cotton - like feel is 1.88 dtex, the breaking strength is 2.93 cN / dtex, the breaking elongation is 20.22%, the crimp shrinkage rate is 10.32%, and the boiling water shrinkage rate is 4.03%; the drape and rebound percentage of the elastic fiber with drape and cotton - like feel woven into a fabric is 17%.

[0077] Example 4

[0078] A method for preparing an elastic fiber with drape and cotton - like feel, the specific process is as follows:

[0079] Pre - oriented polyester fiber with a specification of 190 dtex / 144f is made into an elastic fiber with drape and cotton - like feel through a texturing process;

[0080] The texturing process uses a TMT1500 - FOUR automatic doffing single - strand machine. The texturing process flow is: pre - oriented polyester fiber → pre - network → first feed roller → draw - texturing hot box → cooling plate → false - twister → second feed roller → auxiliary roller → setting hot box → setting feed roller → oiling roller → DTY winding and forming overfeed → elastic fiber;

[0081] The false-twisting device is a friction disc type false-twisting device; both the upper layer inlet disc and the lower layer outlet disc of the false-twisting device adopt smooth discs, and the middle layer adopts 5 polyurethane friction discs;

[0082] The pre-network pressure is 0.16 MPa, the length of the cooling plate is 1.5 m, the speed ratio of the false-twisting device is 1.63, the temperature of the texturing hot box is 235 °C, the setting hot box is closed, the rotational speed of the second feed roller is 500 m / min, the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.33, the overfeed of the setting feed roller is 10%, and the overfeed of the winding and forming is 10%;

[0083] The overfeed of the auxiliary roller is -24.5%, the speed of the auxiliary roller is controlled by a frequency conversion device, and the frequency of the frequency conversion device includes a low frequency and a high frequency; the low frequency is 10 Hz, and the high frequency is 60 Hz; the frequency of the frequency conversion device changes periodically. Within one cycle, the frequency conversion device is first in the low frequency state and then switches to the high frequency state. The time of one cycle is 10 s; within one cycle, the time when the frequency conversion device is in the low frequency state accounts for 40% of the time of one cycle.

[0084] The fineness of the monofilament of the finally prepared elastic fiber with a draping feeling and a cotton feeling is 1.32 dtex, the breaking strength is 3.05 cN / dtex, the breaking elongation is 22.15%, the crimp shrinkage rate is 10.98%, and the boiling water shrinkage rate is 4.75%; the draping and rebound percentage of the elastic fiber with a draping feeling and a cotton feeling woven into a fabric is 25%.

[0085] Example 5

[0086] A preparation method of an elastic fiber with a draping feeling and a cotton feeling is as follows:

[0087] Pre-oriented polyester fiber with a specification of 350 dtex / 144 f is made into an elastic fiber with a draping feeling and a cotton feeling through a texturing process;

[0088] The texturing process uses a TMT1500-FOUR automatic doffing single-strand machine, and the texturing process flow is: pre-oriented polyester fiber → pre-network → first feed roller → texturing hot box → cooling plate → false-twisting device → second feed roller → auxiliary roller → setting hot box → setting feed roller → oiling roller → DTY winding and forming overfeed → elastic fiber;

[0089] The false-twisting device is a friction disc type false-twisting device; both the upper layer inlet disc and the lower layer outlet disc of the false-twisting device adopt smooth discs, and the middle layer adopts 5 polyurethane friction discs;

[0090] The pre-network pressure is 0.19 MPa, the length of the cooling plate is 1.5 m, the false twister speed ratio is 2.13, the temperature of the texturing hot box is 242 °C, the setting hot box is closed, the rotational speed of the second feed roller is 500 m / min, the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.32, the overfeed of the setting feed roller is 9.4%, and the overfeed of the winding forming is 10%;

[0091] The overfeed of the auxiliary roller is -18%, the speed of the auxiliary roller is controlled by a frequency conversion device, and the frequency of the frequency conversion device includes a low frequency and a high frequency; the low frequency is 20 Hz, and the high frequency is 80 Hz; the frequency of the frequency conversion device changes periodically. Within one cycle, the frequency conversion device is first in the low-frequency state and then switches to the high-frequency state. The time of one cycle is 30 s; within one cycle, the time when the frequency conversion device is in the low-frequency state accounts for 20% of the time of one cycle.

[0092] The fineness of the monofilament of the finally produced elastic fiber with a draping feeling and a cotton feeling is 2.43 dtex, the breaking strength is 3.16 cN / dtex, the breaking elongation is 19.78%, the crimp shrinkage rate is 8.92%, and the boiling water shrinkage rate is 3.93%; the draping rebound percentage of the elastic fiber with a draping feeling and a cotton feeling woven into a fabric is 16%.

Claims

1. A method for preparing an elastic fiber with a draping feeling and a cotton feeling, characterized in that: The pre-oriented polyester fiber is made into an elastic fiber with a draping feeling and a cotton feeling through a texturing process; The texturing process flow is: pre-oriented polyester fiber → pre-network → first feed roller → draw texturing heater box → cooling plate → false twister → second feed roller → auxiliary roller → setting heater box → setting feed roller → oiling roller → DTY winding forming overfeed → elastic fiber; The temperature of the draw texturing heater box is 230 - 250 °C; the setting heater box is closed; the rotational speed of the second feed roller is 300 - 600 m / min, and the ratio of the speed of the second feed roller to the speed of the first feed roller is 1.29 - 1.5; The false twister is a friction disc type false twister; both the upper layer input disc and the lower layer output disc of the false twister adopt smooth discs, and the middle layer adopts 5 polyurethane friction discs; the speed ratio of the false twister is 1.5 - 2.13; The overfeed of the auxiliary roller is -24.5% to -16.0%, the speed of the auxiliary roller is controlled by a frequency conversion device, and the frequency of the frequency conversion device includes a low frequency and a high frequency; the low frequency is 10 - 30 Hz, and the high frequency is 50 - 90 Hz; the frequency of the frequency conversion device changes periodically. Within one cycle, the frequency conversion device is first in the low frequency state and then switches to the high frequency state. The time of one cycle is 10 - 30 s; within one cycle, the time that the frequency conversion device is in the low frequency state accounts for 20 - 40% of the time of one cycle.

2. The preparation method of an elastic fiber with a draping feeling and a cotton feeling according to claim 1, characterized in that, The pre-network pressure is 0.15 - 0.20 MPa, the length of the cooling plate is 1 - 1.5 m, the overfeed of the setting feed roller is 8.0 - 10.0%, and the overfeed of the winding forming is 8.0 - 10.0%.

3. The preparation method of an elastic fiber with a draping feeling and a cotton feeling according to claim 1, characterized in that, The texturing process uses a TMT1500 - FOUR automatic doffing single-strand machine.

4. The preparation method of an elastic fiber with a draping feeling and a cotton feeling according to claim 1, characterized in that, The fineness of the pre-oriented polyester fiber is 135 - 600 dtex.

5. An elastic fiber with a draping feeling and a cotton feeling prepared by the preparation method according to any one of claims 1 to 4, characterized in that: The single filament fineness of the elastic fiber with a draping feeling and a cotton feeling is 1.3 - 2.5 dtex, the breaking strength is 2.9 - 3.2 cN / dtex, the breaking elongation rate is 19 - 23%, the crimp shrinkage rate is 8 - 11%, and the boiling water shrinkage rate is 3.9 - 5.0%; the draping resilience percentage of the fabric woven from the elastic fiber with a draping feeling and a cotton feeling is 15 - 26%.

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