Coarse-denier, few-hole and overweight-mesh DTY fiber and preparation method thereof

Abstract

The invention discloses a coarse-denier, few-hole and overweight-mesh DTY fiber and a preparation method thereof, and relates to the technical field of spinning. The preparation method of the coarse-denier, few-hole and overweight-mesh DTY fiber comprises the following steps: step S10, preparing a spinning melt, wherein polydimethylsiloxane is added into the spinning melt; step S20, preparing a pre-oriented yarn; extruding the spinning melt through a spinneret plate, cooling, curing, oiling and winding to obtain the pre-oriented yarn; the spinneret plate is provided with round spinneret orifices and rectangular spinneret orifices, and the number of the rectangular spinneret orifices accounts for 15%-25% of the total number of the spinneret orifices; and S30, carrying out drafting and false twisting processing on the pre-oriented yarn to obtain the heavy-denier, few-hole and overweight-mesh DTY fiber. According to the coarse-denier, few-hole and overweight-net DTY fiber and the preparation method thereof, provided by the invention, the monofilaments can be tightly held, the network fastness is enhanced, and the swelling effect is reduced to better preserve the shape.

Description

Technical Field

[0001] The present invention relates to the field of spinning technology, and in particular to a coarse-denier, low-pore, and ultra-heavy mesh DTY fiber and a preparation method thereof. Background Art

[0002] DTY (Draw Textured Yarn) is a false twist textured yarn, also known as stretch yarn. It is made from polyester chips (PET) through high-speed spinning of polyester pre-oriented yarn (POY), and then through drawing and false twisting. DTY has the characteristics of short process, high efficiency and good quality, and is usually used to produce decorative fabrics, clothing fabrics and linings.

[0003] Coarse denier and few-hole DTY is generally a coarse denier round-hole yarn with no more than 48 holes. The main varieties are 150 / 48, 150 / 36, 200 / 48, etc. It is widely used in downstream water-jet and air-jet woven products. Because of its strong network points, it can be directly used on the machine without sizing. The cross-section of POY used in coarse denier and few-hole DTY is mainly round. Because of its small number of roots, large single-filament fineness, small specific surface area, large gaps between single-filaments, it is difficult for airflow to wrap the single-filaments together. Various types of nozzles are used for stretching, and various air pressures cannot obtain ideal fastness.

[0004] At present, the speed of air jet looms cannot be increased due to the insufficient strength of coarse denier and low-pore DTY, which greatly reduces the product benefits. At present, large-aperture nozzles and high air pressure are used to increase the network strength. However, not only does the network strength not increase significantly, but the high-speed airflow will also break the single filaments and cause hairy fibers. At the same time, the air consumption is increased, resulting in higher production costs. Summary of the invention

[0005] The inventors have found that the cohesion between the monofilaments of flat yarn with a rectangular cross section is much better than that of round yarn with a circular cross section. Flat yarn can greatly improve the resistance to snagging and cutting of fabrics. Flat yarn is a yarn made using a special-shaped spinneret. Because its monofilament cross section is approximately rectangular, it has a larger specific surface area than a circular cross section, which increases the reflection area of ​​light and makes the fabric more lustrous.

[0006] The production process of flat yarn is basically the same as that of ordinary round yarn. However, due to the shear stress on the melt in the spinneret, a large amount of elastic potential energy is stored. After the melt is extruded, elastic recovery occurs. Due to the difference in normal stress in the shear flow of the melt, an expansion zone larger than the die diameter appears after the melt exits the die. The existence of this expansion zone makes it difficult for the rectangular cross section to maintain its shape. How to keep the melt in shape after the exit die is the key to the success of flat yarn production.

[0007] In view of the deficiencies in the prior art, an object of this specification is to provide a coarse denier, low-pore, super-heavy mesh DTY fiber and a preparation method thereof, so that the monofilaments can be tightly hugged, the network fastness is enhanced, and the swelling effect is reduced to better retain the shape.

[0008] To achieve the above-mentioned purpose, the present application provides a method for preparing a coarse-denier, low-pore, and super-heavy mesh DTY fiber, comprising the following steps: Step S10: preparing a spinning melt, wherein polydimethylsiloxane is added to the spinning melt; Step S20: preparing pre-oriented yarns; extruding the spinning melt through a spinneret, cooling and solidifying, oiling and winding to obtain the pre-oriented yarns; the spinneret is provided with circular spinneret holes and rectangular spinneret holes, and the number of the rectangular spinneret holes accounts for 15% to 25% of the total number of spinneret holes; Step S30: The pre-oriented yarn is subjected to a drawing and false twisting process to obtain a coarse-denier, low-pore, and ultra-heavy mesh DTY fiber.

[0009] As a preferred implementation, step S10 includes the following steps: Step S11: preparing terephthalic acid and ethylene glycol into a slurry; Step S12: adding a catalyst, a stabilizer and polydimethylsiloxane to the slurry for esterification reaction to obtain dihydroxyethylene terephthalate; the catalyst is one of antimony trioxide, ethylene glycol antimony or antimony acetate, and the stabilizer is one of triphenyl phosphate, trimethyl phosphate or trimethyl phosphite; Step S13: sequentially subjecting the dihydroxyethylene terephthalate to polycondensation reactions in a near vacuum stage and a high vacuum stage to obtain the spinning melt.

[0010] As a preferred embodiment, the molar ratio of terephthalic acid to ethylene glycol is 1:1.2~2.0; the degree of polymerization of the polydimethylsiloxane is 5~12, the melting point is -40°C~-30°C, the dynamic viscosity is ≤1Pa·s, the mass of the polydimethylsiloxane is 0.2%~0.5% of the mass of the slurry; the amount of the catalyst added is 0.01%~0.05% of the weight of the terephthalic acid; the amount of the stabilizer added is 0.01%~0.05 of the weight of the terephthalic acid.

[0011] As a preferred embodiment, the esterification reaction is carried out in a nitrogen pressurized atmosphere, and the pressurized pressure is normal pressure to 0.3 MPa; the temperature of the esterification reaction is 250°C to 260°C; in the near-vacuum stage, the reaction pressure is steadily pumped from normal pressure to an absolute pressure of less than 500 Pa, the reaction temperature is controlled at 260°C to 270°C, and the reaction time is 30min to 50min; in the high vacuum stage, the reaction pressure is controlled at an absolute pressure of less than 100Pa, the reaction temperature is controlled at 275°C to 285°C, and the reaction time is 50min to 90min.

[0012] As a preferred embodiment, in the step S20, the area of ​​the circular spinneret is equal to the area of ​​the rectangular spinneret; the outlet surface of the spinneret plate is provided with four circles of spinneret holes, which are circular spinneret holes, rectangular spinneret holes, circular spinneret holes and circular spinneret holes from the inside to the outside; each circle of spinneret holes is evenly spaced in the circumferential direction, and the center lines of each circle of spinneret holes form four concentric circles.

[0013] As a preferred embodiment, the aspect ratio of the rectangular spinneret is 8-12, and the long side of the rectangular spinneret is parallel to the radial direction; the diameter of the circular spinneret is 0.26 mm-0.30 mm; and the spacing between adjacent spinnerets is above 2.2 mm.

[0014] As a preferred embodiment, the expansion ratio of the spinning melt extruded from the spinneret is 1.08-1.25.

[0015] As a preferred embodiment, the pre-oriented yarn prepared in step S20 has a fineness of 260dtex~350dtex, a linear density deviation of ≤0.5%; a breaking strength of ≥2.58cn / dtex, and a breaking strength variation coefficient of ≤4%; a breaking elongation of 135±3%, and a breaking elongation variation coefficient of ≤8%; a yarn unevenness variation coefficient of ≤2%; and a flatness of ≥3.

[0016] The embodiment of the present application further provides a coarse denier, few-pore, and extra-heavy mesh DTY fiber, wherein the coarse denier, few-pore, and extra-heavy mesh DTY fiber is prepared by the preparation method described in any one of the above embodiments.

[0017] As a preferred embodiment, the linear density of the coarse denier low-pore extra-heavy mesh DTY fiber is 167dtex~200dtex, and the linear density deviation is ≤1%; the breaking strength is ≥3.9cn / dtex, and the breaking strength variation coefficient is ≤2%; the breaking elongation is ≥18%, and the breaking elongation variation coefficient is ≤8%. Beneficial Effects

[0018] The preparation method of the coarse denier, low-pore, super-heavy mesh DTY fiber provided in this embodiment redesigns the spinneret and introduces a certain proportion (15% to 25%) of rectangular spinneret holes to increase the specific surface area of ​​the monofilaments, increase the contact surface between the monofilaments, enable the monofilaments to be tightly hugged, enhance the network strength, and provide a solution to the problem of difficulty in maintaining the shape of the rectangular cross-section due to extrusion expansion, thereby producing POY (pre-oriented yarn) that meets the requirements of the super-heavy mesh, and the super-heavy mesh DTY is obtained after the POY is stretched, deformed, and the middle network is combined.

[0019] The present invention adds polydimethylsiloxane, whose chemical formula is (CH3)3SiO2((CH3)2SiO)nSi(CH3)3, to the polyester melt to enhance the lubricity of the melt and the wall of the spinneret hole during extrusion, which can effectively reduce the pressure drop of the melt in the spinneret hole, thereby reducing the shear stress of the melt, reducing the normal stress difference, and relaxing the melt faster in the spinneret hole, effectively reducing the extrusion expansion phenomenon, that is, reducing the extrusion expansion ratio, so that the product has a good shape-keeping effect. In addition, polydimethylsiloxane has no damage to the structure of the polyester fiber, and maintains the excellent performance of the polyester fiber. Its refractive index is 1.402-1.403, which is less than the refractive index of polyester (1.52-1.54), and not only does it not affect the transparency of the product, but also increases the brightness of the polyester fiber.

[0020] With reference to the following description and the accompanying drawings, the specific embodiments of the present invention are disclosed in detail, indicating the manner in which the principles of the present invention can be adopted. It should be understood that the embodiments of the present invention are not limited in scope thereby.

[0021] Features described and / or illustrated with respect to one embodiment may be used in the same or similar manner in one or more other embodiments, combined with features in other embodiments, or substituted for features in other embodiments.

[0022] It should be emphasized that the term “include / comprises” when used herein refers to the presence of features, integers, steps or components, but does not exclude the presence or addition of one or more other features, integers, steps or components. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without paying any creative labor.

[0024] Figure 1 A flowchart of the steps of a method for preparing a coarse-denier, low-pore, and ultra-heavy mesh DTY fiber provided in this embodiment; Figure 2 A top view of a spinneret provided in this embodiment; Figure 3 A bottom view of a spinneret provided in this embodiment; Figure 4 It is a schematic diagram of a partial cross-sectional structure of a spinneret provided in this embodiment.

[0025] Description of reference numerals: 1. Spinneret; 2. Spinneret hole; 21. Circular spinneret hole; 22. Rectangular spinneret hole; 3. Inlet. DETAILED DESCRIPTION

[0026] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0027] It should be noted that when an element is referred to as being "disposed on" another element, it may be directly on the other element or there may be another element centered thereon. When an element is considered to be "connected to" another element, it may be directly connected to the other element or there may be another element centered thereon at the same time. The terms "vertical", "horizontal", "left", "right" and similar expressions used herein are for illustrative purposes only and do not represent the only implementation method.

[0028] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used herein in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used herein includes any and all combinations of one or more related listed items.

[0029] See also Figure 1 The present application provides a method for preparing a coarse-denier, low-pore, and ultra-heavy mesh DTY fiber, comprising the following steps: Step S10: preparing a spinning melt, wherein polydimethylsiloxane is added to the spinning melt; Step S20: preparing pre-oriented yarns; extruding the spinning melt through a spinneret 1, cooling and solidifying, oiling and winding to obtain the pre-oriented yarns; the spinneret 1 is provided with circular spinneret holes 21 and rectangular spinneret holes 22, and the number of the rectangular spinneret holes 22 accounts for 15% to 25% of the total number of the spinneret holes 2; Step S30: The pre-oriented yarn is subjected to a drawing and false twisting process to obtain a coarse-denier, low-pore, and ultra-heavy mesh DTY fiber.

[0030] The preparation method of the coarse denier, low-pore, super-heavy mesh DTY fiber provided in this embodiment redesigns the spinneret 1 and introduces a certain proportion (15% to 25%) of rectangular spinneret holes 22 to increase the specific surface area of ​​the monofilaments, increase the contact surface between the monofilaments, enable the monofilaments to be tightly hugged, enhance the network strength, and provide a solution to the problem of difficulty in maintaining the shape of the rectangular cross-section due to extrusion expansion, thereby producing POY (pre-oriented yarn) that meets the requirements of the super-heavy mesh, and the super-heavy mesh DTY is obtained after the POY is stretched, deformed, and the middle network is closed.

[0031] Among them, the proportion of rectangular spinneret holes 22 is 15% to 25%. This is because if the proportion of rectangular spinneret holes 22 is less than 15%, it cannot meet the requirements of the super-heavy net, and the final DTY network strength is not enough; if the proportion of rectangular spinneret holes 22 is greater than 25%, it will cause the POY strength and elongation to decrease, and the DTY strength and elongation will also decrease. At the same time, since the rectangular spinneret holes 22 are special-shaped holes, compared with the round holes, the shear rate difference is large. If the process control is not good, it is easy to cause skin-core wire, which increases the difficulty of processing. The number of rectangular spinneret holes 22 accounts for 15% to 25% of the total number of spinneret holes 2, which can meet the requirements of the super-heavy net. For example, the number of rectangular spinneret holes 22 can be 8, 10, 12, etc., and the total number of spinneret holes 2 of the corresponding spinneret plate 1 can be 48, 60, 72, etc.

[0032] The present invention adds polydimethylsiloxane, whose chemical formula is (CH3)3SiO2((CH3)2SiO)nSi(CH3)3, to the polyester melt to enhance the lubricity of the melt and the wall of the spinneret hole 2 during extrusion, which can effectively reduce the pressure drop of the melt in the spinneret hole 2, thereby reducing the shear stress of the melt, reducing the normal stress difference, and relaxing the melt faster in the spinneret hole 2, effectively reducing the extrusion expansion phenomenon, that is, reducing the extrusion expansion ratio, so that the product has a good shape-keeping effect. In addition, polydimethylsiloxane has no damage to the structure of the polyester fiber, maintains the excellent performance of the polyester fiber, and its refractive index is 1.402~1.403, which is less than the refractive index of polyester (1.52~1.54), and not only does it not affect the transparency of the product, but also increases the brightness of the polyester fiber.

[0033] Specifically, the methyl group -CH3 of polydimethylsiloxane is a non-polar group, which is compatible with the non-polar polyester melt, while its siloxy group -SiO- is a polar group, which is not compatible with the polyester melt, and the dynamic viscosity of polydimethylsiloxane is much lower than that of the polyester melt. This characteristic allows the polydimethylsiloxane to flow and migrate to the polyester surface in the polyester melt, and form an interface film effect with the metal surface of the spinneret hole 2. The formed interface film effectively reduces the friction force on the melt on the wall of the spinneret hole 2, thereby reducing the pressure drop, reducing the shear stress and the normal stress difference, reducing the expansion effect of the melt after exiting the spinneret hole 2, and enabling the rectangular spinneret hole 22 to better maintain its shape.

[0034] In this embodiment, the step S10 specifically includes the following steps: Step S11: preparing terephthalic acid and ethylene glycol into a slurry; Step S12: adding a catalyst, a stabilizer and polydimethylsiloxane to the slurry for esterification reaction to obtain bis(hydroxyethylene terephthalate); Step S13: sequentially subjecting the dihydroxyethylene terephthalate to polycondensation reactions in a near vacuum stage and a high vacuum stage to obtain the spinning melt.

[0035] Wherein, in step S11, the molar ratio of terephthalic acid to ethylene glycol is 1:1.2~2.0. In step S12, the catalyst is one of antimony trioxide, ethylene glycol antimony or antimony acetate. The amount of the catalyst added is 0.01%~0.05% of the weight of the terephthalic acid. The stabilizer is one of triphenyl phosphate, trimethyl phosphate or trimethyl phosphite. The amount of the stabilizer added is 0.01%~0.05 of the weight of the terephthalic acid.

[0036] The degree of polymerization of the polydimethylsiloxane is 5 to 12, that is, in (CH3)3SiO2((CH3)2SiO)nSi(CH3)3, the value of n is 5 to 12. The melting point of the polydimethylsiloxane is -40°C to -30°C, and the dynamic viscosity is ≤1Pa·s. The mass of the polydimethylsiloxane is 0.2% to 0.5% of the mass of the slurry.

[0037] Specifically, the esterification reaction in step S12 is carried out in a nitrogen pressurized atmosphere, and the pressurized pressure is normal pressure to 0.3 MPa. The temperature of the esterification reaction is 250° C. to 260° C. When the amount of water distilled out in the esterification reaction reaches more than 90% of the theoretical value, it is considered that the esterification reaction ends, and at this time, the reactant is mainly the oligomer BHET bis(hydroxyethylene terephthalate).

[0038] In step S13, in the near-vacuum stage, the reaction pressure is steadily pumped from normal pressure to an absolute pressure of less than 500 Pa, the reaction temperature is controlled at 260°C to 270°C, and the reaction time is 30 min to 50 min. Then, the vacuum is continued, and in the high-vacuum stage, the reaction pressure is controlled at an absolute pressure of less than 100 Pa, the reaction temperature is controlled at 275°C to 285°C, and the reaction time is 50 min to 90 min.

[0039] In this embodiment, in the step S20, the area of ​​the circular spinneret hole 21 is made equal to the area of ​​the rectangular spinneret hole 22 to ensure the same outlet flow rate, the same stretching multiple, and the same thickness of the filaments.

[0040] like Figure 2 and Figure 3 As shown, the spinneret 1 is provided with four circles of spinneret holes 2, which are one circle of circular spinneret holes 21, one circle of rectangular spinneret holes 22, one circle of circular spinneret holes 21 and one circle of circular spinneret holes 21 from the inside to the outside. Correspondingly, the spinneret 1 is provided with four circles of inlets 3, which may be circular. Each circle of spinneret holes 2 is evenly spaced in the circumferential direction, and the center line of each circle of spinneret holes 2 forms four concentric circles. The spacing between adjacent spinneret holes 2 is above 2.2 mm to ensure uniform cooling.

[0041] Specifically, the aspect ratio of the rectangular spinneret 22 is 8 to 12 to ensure that the flatness of the pre-oriented yarn formed subsequently is above 3.0, for example, it can be 3.2. The aspect ratio of the rectangular spinneret 22 is 8 to 12, which is a necessary condition to ensure that the flatness of the finished product is greater than or equal to 3.0. If the aspect ratio is lower than this range, the flatness of the finished product will not reach 3.0, and the super-heavy net effect is not good; if the aspect ratio is higher than this range, the POY skin-core structure is serious and the strength and elongation are reduced. The long side of the rectangular spinneret 22 is parallel to the radial direction, that is, the rectangular spinneret 22 is arranged evenly and concentrically on the inside, which is convenient for contact and embracing with the surrounding monofilaments. The diameter of the circular spinneret 21 is 0.26 mm to 0.30 mm, which is a suitable range for processing 150D to 250D fibers. When the diameter of the circular spinneret 21 is less than 0.26mm, the shear rate is too high, which may cause melt fracture and failure of normal spinning; when the diameter of the circular spinneret 21 is greater than 0.30mm, the melt stays in the spinneret for too long, which may cause the melt to degrade and turn yellow, and the pressure of the component to drop, which may cause leakage and floating of the filaments. The diameter of the spinneret 1 is set to 80mm~95mm, and the aspect ratio of the die end (i.e., the aspect ratio of the spinneret 1, the ratio of the length to the diameter at the outlet of the spinneret 1, i.e., Figure 4 The ratio of the height to the diameter of the spinneret hole 2 shown is 3.0 to 3.5.

[0042] In step S20, the spinning temperature is maintained at 270°C~300°C, the initial pressure of the spinneret 1 (i.e., the pressure of the spinning melt entering the spinneret) is 8MPa~12MPa, the height of the windless zone is 50mm~70mm, the annular blowing pressure is 50Pa~60Pa, the cooling temperature is 20°C~30°C, the oil rack height is 900mm~1200mm, and the spinning speed is 2500m / min~2800m / min.

[0043] According to the dynamic image of the spinning melt extruded from the spinneret 2, a three-dimensional simulation dynamic graph is established to calculate the ratio of the maximum cross-sectional area and the diameter of the spinneret 2 and the extrusion expansion ratio corresponding to the spinning melt extruded from the spinneret 2. After multiple groups of measurements, the expansion ratio of the spinning melt extruded from the spinneret 2 in this embodiment is 1.08-1.25.

[0044] In this embodiment, the fineness of the pre-oriented yarn prepared in step S20 is 260dtex~350dtex, the linear density deviation is ≤0.5%; the breaking strength is ≥2.58cn / dtex, the breaking strength CV (coefficient of variation) is ≤4%; the breaking elongation is 135±3%, the breaking elongation CV≤8%; the yarn unevenness CV≤2%.

[0045] In step S30, the specific process route can be: one roller - one hot box - cooling plate - false twister - tension meter - network nozzle - auxiliary roller - two hot boxes - three rollers - black roller - winding. Among them, the processing speed is 680m / min~750m / min, the temperature of the first hot box is 185℃~195℃, the disc combination is 1-5-1, the nozzle model is P213, the network pressure is 0.28MPa~0.36MPa, and the temperature of the second hot box is 165℃~175℃. The function of the auxiliary roller is to make the silk strip have a stable tension, which is convenient for network making. Specifically, the pre-oriented yarn (POY finished product) is heated by a heat box and stretched between a first roller and a second roller. The stretched POY is cooled and solidified by a cooling plate and sent to a false twister for false twisting deformation. After the stretched and false twisted POY comes out of the second roller, it is netted through a middle net nozzle between the second roller and the auxiliary roller. The netted POY enters the second heat box through the auxiliary roller for heat setting. The heat-set POY passes through the third roller and is wound on a black roller to obtain a DTY finished product (i.e., coarse denier, low-pore, and ultra-heavy net DTY fiber).

[0046] The coarse denier low-pore extra-heavy mesh DTY fiber prepared in step S30 has a linear density of 167 dtex to 200 dtex, a linear density deviation of ≤1%, a breaking strength of ≥3.9 cn / dtex, and a breaking strength CV of ≤2%, and a breaking elongation of ≥18%, and a breaking elongation CV of ≤8%.

[0047] Based on the same concept, a coarse denier, few-pore, and extra-heavy mesh DTY fiber is also provided in an embodiment of the present invention. The coarse denier, few-pore, and extra-heavy mesh DTY fiber is prepared by the preparation method provided by any one of the above embodiments.

[0048] In this embodiment, the implementation method of the coarse denier low-pore ultra-heavy mesh DTY fiber corresponds to the implementation method of the preparation method, which can solve the technical problems solved by the implementation method of the preparation method and correspondingly achieve the technical effects of the implementation method of the preparation method. The specific application will not be repeated here.

[0049] In a specific application scenario, a spinneret 1 with a specification of 167 / 48 (i.e., a linear density of 167 dtex and a number of holes of 48, which means that a DTY of 10,000 meters in length has a total weight of 167 g and is composed of 48 monofilaments) is selected, the number of rectangular spinnerets 22 in the spinneret 1 accounts for 16.6% of the total number of spinnerets 2, and the number of circular spinnerets 21 accounts for 83.4% of the total number of spinnerets 2. The coarse denier, low-pore, and ultra-heavy web DTY fiber prepared by the preparation method provided in the embodiment of the present application has network numbers of 110, 111, 110, 112, 111, and 109 at spindle positions 193, 194, 195, 196, 197, and 198, respectively, and the network fastness is heavy.

[0050] For comparison, a spinneret with a specification of 167 / 48 was selected, in which all the spinnerets were circular but not rectangular. The same texturizing process as mentioned above was adopted, and the numbers of networks at spindles 193, 194, 195, 196, 197 and 198 were 101, 103, 101, 102, 99 and 100 respectively, and the network fastness was light.

[0051] It can be found that compared with a spinneret with only circular spinnerets, introducing a certain proportion of rectangular spinnerets 22 can make the produced fiber have better network cohesion.

[0052] The criteria for determining the super heavy net described in the present application are: from the perspective of the number of network points, for example, for a 167 / 48 super heavy net P213 nozzle, the number of network points should be no less than 110 / m; from the perspective of network fastness, the super heavy net DTY is not easy to be pulled apart, while the general heavy net is relatively easy to be pulled apart; from the perspective of water jet or air jet weaving, the super heavy net DTY can be used directly without sizing, and has high efficiency, while the general heavy net needs to be slightly sizing before use, and the process is complicated and the processing cost is high.

[0053] It should be noted that, in the description of this specification, unless otherwise specified, “plurality” means two or more.

[0054] Any numerical value cited herein includes all values ​​of lower and upper values ​​that increase by one unit from the lower limit to the upper limit, and there is at least a two-unit interval between any lower value and any higher value. For example, if the value of the quantity of a component or a process variable (such as temperature, pressure, time, etc.) is set forth to be from 1 to 90, preferably from 20 to 80, and more preferably from 30 to 70, the purpose is to illustrate that values ​​such as 15 to 85, 22 to 68, 43 to 51, 30 to 32 are also explicitly listed in the specification. For values ​​less than 1, one unit is appropriately considered to be 0.0001, 0.001, 0.01, 0.1. These are merely examples that are intended to be clearly expressed, and it can be considered that all possible combinations of numerical values ​​listed between the lowest value and the highest value are clearly set forth in the specification in a similar manner.

[0055] Unless otherwise specified, all ranges include the endpoints and all numbers between the endpoints. "About" or "approximately" used with a range applies to both endpoints of the range. Thus, "about 20 to 30" is intended to cover "about 20 to about 30", including at least the specified endpoints.

[0056] All articles and references disclosed, including patent applications and publications, are incorporated herein by reference for all purposes. The term "consisting essentially of..." to describe a combination should include the identified elements, ingredients, parts or steps and other elements, ingredients, parts or steps that do not substantially affect the basic novel characteristics of the combination. The use of the terms "comprising" or "including" to describe a combination of elements, ingredients, parts or steps herein also contemplates embodiments that consist essentially of these elements, ingredients, parts or steps. By using the term "may", it is intended to indicate that any attribute described that "may" include is optional.

[0057] Multiple elements, ingredients, parts or steps can be provided by a single integrated element, ingredient, part or step. Alternatively, a single integrated element, ingredient, part or step can be divided into separate multiple elements, ingredients, parts or steps. The disclosure "one" or "an" used to describe an element, ingredient, part or step is not intended to exclude other elements, ingredients, parts or steps.

[0058] It should be understood that the above description is for illustration and not for limitation. Many embodiments and many applications beyond the examples provided will be apparent to those skilled in the art upon reading the above description. Therefore, the scope of the present teachings should not be determined with reference to the above description, but should be determined with reference to the appended claims and the full scope of equivalents possessed by such claims. For the purpose of comprehensiveness, all articles and references, including disclosures of patent applications and publications, are incorporated herein by reference. The omission of any aspect of the subject matter disclosed herein in the preceding claims is not intended to be a waiver of the subject matter, nor should it be considered that the inventors did not consider the subject matter to be part of the disclosed inventive subject matter.

Claims

1. A method for preparing coarse denier, low-pore, super-heavy mesh DTY fiber, characterized in that: The following steps are involved: step S10: preparing a spinning melt, wherein polydimethylsiloxane is added to the spinning melt; Step S20: preparing pre-oriented yarns; Extruding the spinning melt through a spinneret, cooling and solidifying, and then oiling and winding to obtain the pre-oriented yarn; The spinneret is provided with circular spinneret holes and rectangular spinneret holes, and the number of the rectangular spinneret holes accounts for 15% to 25% of the total number of spinneret holes; Step S30: The pre-oriented yarn is subjected to a drawing and false twisting process to obtain a coarse-denier, low-pore, and ultra-heavy mesh DTY fiber.

2. The method for preparing the coarse-denier, low-pore, super-heavy mesh DTY fiber according to claim 1, characterized in that: The step S10 comprises the following steps: Step S11: preparing terephthalic acid and ethylene glycol into a slurry; Step S12: adding a catalyst, a stabilizer and polydimethylsiloxane to the slurry for esterification reaction to obtain dihydroxyethylene terephthalate; the catalyst is one of antimony trioxide, ethylene glycol antimony or antimony acetate, and the stabilizer is one of triphenyl phosphate, trimethyl phosphate or trimethyl phosphite; Step S13: sequentially subjecting the dihydroxyethylene terephthalate to polycondensation reactions in a near vacuum stage and a high vacuum stage to obtain the spinning melt.

3. The method for preparing the coarse-denier, low-pore, super-heavy mesh DTY fiber according to claim 2, characterized in that: The molar ratio of terephthalic acid to ethylene glycol is 1:1.2~2.0; the degree of polymerization of the polydimethylsiloxane is 5~12, the melting point is -40℃~-30℃, the dynamic viscosity is ≤1Pa·s, and the mass of the polydimethylsiloxane is 0.2%~0.5% of the mass of the slurry; the amount of the catalyst added is 0.01%~0.05% of the weight of the terephthalic acid; the amount of the stabilizer added is 0.01%~0.05% of the weight of the terephthalic acid.

4. The method for preparing coarse-denier, low-pore, super-heavy mesh DTY fiber according to claim 3, characterized in that: The esterification reaction is carried out in a nitrogen pressurized atmosphere, and the pressurized pressure is normal pressure to 0.3MPa; the temperature of the esterification reaction is 250°C to 260°C; in the near-vacuum stage, the reaction pressure is steadily pumped from normal pressure to an absolute pressure below 500Pa, the reaction temperature is controlled at 260°C to 270°C, and the reaction time is 30min to 50min; in the high-vacuum stage, the reaction pressure is controlled at an absolute pressure below 100Pa, the reaction temperature is controlled at 275°C to 285°C, and the reaction time is 50min to 90min.

5. The method for preparing coarse denier, low-pore, super-heavy mesh DTY fiber according to claim 1, characterized in that: In step S20, the area of ​​the circular spinneret is equal to the area of ​​the rectangular spinneret; the outlet surface of the spinneret plate is provided with four circles of spinneret holes, which are circular spinneret holes, rectangular spinneret holes, circular spinneret holes and circular spinneret holes from the inside to the outside; each circle of spinneret holes is evenly spaced in the circumferential direction, and the center lines of each circle of spinneret holes form four concentric circles.

6. The method for preparing coarse-denier, low-pore, super-heavy mesh DTY fiber according to claim 5, characterized in that: The aspect ratio of the rectangular spinneret is 8-12, and the long side of the rectangular spinneret is parallel to the radial direction; the diameter of the circular spinneret is 0.26 mm-0.30 mm; and the spacing between adjacent spinnerets is above 2.2 mm.

7. The method for preparing coarse-denier, low-pore, super-heavy mesh DTY fiber according to claim 6, characterized in that: The expansion ratio of the spinning melt extruded from the spinneret hole is 1.08-1.

25.

8. The method for preparing coarse-denier, low-pore, super-heavy mesh DTY fiber according to claim 1, characterized in that: The fineness of the pre-oriented yarn prepared in step S20 is 260dtex~350dtex, the linear density deviation is ≤0.5%; the breaking strength is ≥2.58cn / dtex, the breaking strength variation coefficient is ≤4%; the breaking elongation is 135±3%, the breaking elongation variation coefficient is ≤8%; the yarn unevenness variation coefficient is ≤2%; and the flatness is ≥3.

9. A coarse denier, low-pore, super-heavy mesh DTY fiber, characterized in that: The coarse denier, low-pore, and ultra-heavy mesh DTY fiber is prepared by the preparation method described in any one of claims 1 to 8.

10. The coarse-denier, low-pore, super-heavy mesh DTY fiber according to claim 9, characterized in that: The coarse denier, low-pore, super-heavy mesh DTY fiber has a linear density of 167 dtex to 200 dtex, a linear density deviation of ≤1%, a breaking strength of ≥3.9 cn / dtex, a breaking strength variation coefficient of ≤2%, a breaking elongation of ≥18%, and a breaking elongation variation coefficient of ≤8%.

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