A method for improving the quality of fine-denier split polyester-nylon composite yarn

Abstract

This invention belongs to the field of spinning processing technology and relates to a method for improving the quality of fine denier split polyester-nylon composite yarn. The fine denier split polyester-nylon composite yarn contains nylon with a content of 10-30 wt%. The preparation process is as follows: polyester melt and nylon melt are transported into the spinning box through their respective pipelines. Then, the polyester melt and nylon melt enter their respective sand cups through their respective channels, are pressurized and filtered, and then enter the distribution plate. After passing through the distribution plate, they converge and fuse according to the designed split shape and are extruded into filaments from the spinneret. Finally, the filaments undergo cooling, oiling, stretching, heat setting, and winding to form fine denier split polyester-nylon composite yarn. The temperature difference between the nylon melt and the polyester melt is controlled to be [missing information - likely a temperature range]. D The prepared product has a fiber opening rate >99%, a dyeing M rate >99.5%, and a fuzz rate <0.5% after fiber opening. The method of this invention can obtain fine denier split-type polyester-nylon composite yarn with clear interfaces and no cross-sectional deformation.

Description

Technical Field

[0001] This invention belongs to the field of spinning processing technology and relates to a method for improving the quality of fine denier split polyester-nylon composite yarn. Background Technology

[0002] Split-type polyester-nylon composite yarn is a circular cross-section fiber composed of nylon shaped like a starfish with polyester embedded between the points of the starfish. The nylon and polyester are then split apart in a subsequent fiber-opening process to form ultrafine fibers. The finished fabric has advantages such as a delicate feel, soft hand texture, strong moisture absorption, and good drape.

[0003] like Figure 1 As shown, the one-step production of split-type polyester-nylon composite fiber involves two polymer melts, polyester and nylon, which are transported into the spinning box through polyester melt pipes and nylon melt pipes, respectively. The spinning box consists of a polyester main box 2 and a nylon auxiliary box 1. Due to the different properties of the two polymer melts, the two boxes are insulated with heat transfer media of different properties, and a heat insulation layer 3 is installed between the main and auxiliary boxes. Polyester metering pumps 5 and nylon metering pumps 4, located within their respective boxes, accurately meter the two melts according to the process ratio. The polyester and nylon melts then enter the spinning assembly 8, which is insulated by the polyester main box, through connecting pipes 7 (connected to the output end of the polyester metering pump) and 6 (connected to the output end of the nylon metering pump), respectively. Figure 3 , Figure 5 As shown, polyester and nylon enter their respective sand cups through the polyester melt main channel 10 and nylon melt main channel 9 on the component cover. After being filtered and pressurized by metal sand and a filter screen, they enter the distribution plate for diversion. The distribution plate is composed of a first, second, and third distribution plate from top to bottom. At the upper edges of the first, second, and third distribution plates, the polyester and nylon melts are divided into several fine streams in a ring array within their respective channels. Finally, they converge and fuse at the lower edge of the third distribution plate according to the designed slit shape, and are extruded into filaments from the spinneret orifice. After cooling, oiling, stretching, and heat setting, they are wound into slit-type polyester-nylon composite fibers. After subsequent fiber opening, the polyester and nylon are split to finally form ultrafine fibers.

[0004] The main problems in producing fine denier split polyester-nylon composite yarns are as follows: Due to the approximately 20°C temperature difference between the two melts (both within the box and within the melt itself), the low nylon content (typically 10-30 wt%), and slow flow rate, the nylon and polyester melts entering the module are distributed adjacently. This is especially true in the distribution plate where the channels are narrow and the ring arrays are adjacent, resulting in constant high-low temperature transfer between nylon and polyester, and between nylon and the main box (even with gaps between the module and the box, tests show that the temperature difference between the module's outer wall and the box's slot wall is less than 10°C, but for nylon, this still represents a temperature difference of over 10°C). Given sufficient time, this heat transfer becomes even more complete. Furthermore, the viscosity of the nylon melt changes in ultra-high temperature environments, and over time, thermal degradation occurs, affecting melt quality. When fused with polyester, cross-sectional deformation occurs, impacting the quality of the finished fiber.

[0005] In Reference 1 (Discussion on the Influence of POY Spinning of Cross-Shaped Polyester-Nylon Composite Yarn on DTY Finished Yarn Dyeing [J]. Polyester Industry, 2018, 31(4):4.), the melting point of polyester with an intrinsic viscosity of 0.67 dl / g was 260℃, and the melting point of nylon with a relative viscosity of 2.75 was 235℃. The box temperature of polyester was 287~290℃, and the box temperature of nylon was 265~270℃, all of which were 25~35℃ higher than the melting point. Nylon is easily degraded, and after degradation, the uniformity of the melt deteriorates, affecting the cross-sectional stability and causing cross-sectional deformation.

[0006] In reference 2 (Discussion on the application and production process of polyester-nylon composite yarn [J]. Synthetic Fiber, 2012(5):2.), the spinning temperature of polyester-nylon composite yarn must ensure that the melting temperature difference between the two chips is controlled within 15℃ in order to ensure a good fiber cross-sectional image (because a large temperature difference makes it easy to form fuzzy fibers during subsequent stretching, which is difficult to process). However, a small melting temperature difference makes the two components easy to stick together and difficult to peel off.

[0007] Therefore, it is of great significance to study a method to improve the quality of fine denier split polyester-nylon composite yarn in order to solve the problems existing in the current technology. Summary of the Invention

[0008] The purpose of this invention is to solve the problems existing in the prior art and provide a method for improving the quality of fine denier split polyester-nylon composite yarn.

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

[0010] A method for improving the quality of fine denier split polyester-nylon composite yarn, wherein the nylon content in the fine denier split polyester-nylon composite yarn is 10-30 wt%; the preparation process of the fine denier split polyester-nylon composite yarn is as follows: polyester melt and nylon melt are transported into a spinning box through their respective pipelines. The spinning box consists of a main polyester box and a secondary nylon box, and the two boxes are independently temperature-controlled. Metering pumps located in their respective boxes accurately meter the two melts according to the process ratio, and then the melts enter the same spinning assembly located in the main polyester box. In the spinning assembly, the polyester melt and nylon melt are respectively... After passing through their respective channels on the component cover, the fibers enter their respective sand cups, are pressurized and filtered, and then enter the distribution plate. After passing through the distribution plate, they converge and fuse according to the designed slit shape, and are extruded into filaments from the spinneret. Finally, the filaments undergo cooling, oiling, stretching, heat setting, and winding to produce fine denier slit-type polyester-nylon composite yarn. The temperature difference between the nylon melt and the polyester melt is controlled to be D when they enter the spinneret. After the fine denier slit-type polyester-nylon composite yarn is opened, the polyester and nylon are separated to form ultrafine fibers with an opening rate >99%, a dyeing M rate >99.5%, and a fuzz rate <0.5%.

[0011] ;

[0012] In the formula, Tm a Tm is the melting point of polyester. b Tm is the melting point of nylon. a +A represents the chamber temperature setting range for the polyester melt. A refers to the difference between the chamber temperature of the polyester melt and the melting point of polyester. The value of A ranges from 25 to 30℃. Tm b +B represents the set temperature range of the nylon melt chamber. B refers to the difference between the chamber temperature of the nylon melt and the melting point of the nylon. The value of B ranges from 30 to 35℃. K is a coefficient, obtained through numerous experiments, and the value of K ranges from 0.45 to 0.55.

[0013] In split-type polyester-nylon composite monofilaments, the main function of the nylon component is to split the polyester into six arc-shaped triangles. Nylon raw materials are more expensive than polyester (generally twice as expensive), so a lower nylon percentage is better. Currently, the production percentage is typically 10-30 wt%. Due to the low nylon percentage in this type of product, especially for fine denier filaments, the residence time of the nylon melt within the module is significantly extended. High- and low-temperature heat transfer between polyester and nylon, and between the module and nylon within the main housing, is more efficient than in other types of products. This results in a smaller temperature difference during fusion between polyester and nylon compared to other varieties. Furthermore, the temperature difference during fusion has a greater impact on split-type products than on other types, and it has a greater influence on cross-sectional deformation. Currently, other types of this type (split-type) (such as split-type polyester-nylon composite yarn with nylon content exceeding 30%, and coarse denier split-type polyester-nylon composite yarn) have short residence times of nylon melt within the module (the melt capacity within the module is a fixed value, and the residence time of the melt within the module = melt capacity / amount of melt ejected from the module per unit time; fine denier yarn ejects less per unit time than coarse denier yarn, resulting in a longer residence time; polyester-nylon composite yarn has a lower nylon content, resulting in even less melt ejected from the module per unit time, resulting in a longer residence time). This leads to insufficient high and low temperature heat transfer within the module. With existing technology, simply adjusting the chamber temperature can control the temperature difference during the fusion of the two melts to be within an acceptable range, without affecting cross-sectional deformation. Alternatively, for other types (such as core-sheath type and island type), the impact of the temperature difference during fusion on cross-sectional deformation is far lower than that of the split-type, and simply adjusting the chamber temperature can also produce high-quality products.

[0014] In the production of fine denier split polyester-nylon composite yarn, when the two melts are fused, if the nylon temperature is too high, the nylon melt viscosity and surface tension decrease, leading to excessive wetting of the polyester melt and encroachment on the shrinkage space of the nylon melt. This causes the polyester fibers (arc-triangular) to adhere together, resulting in an unclear interface and a deformed cross-section. When the nylon undergoes thermal degradation due to prolonged overheating, the uniformity of the nylon melt deteriorates, severely affecting the melt dispersion morphology. When fused with polyester, this produces a more chaotic cross-sectional configuration and affects the continuity of the yarn along its length, leading to poor spinnability and breakage. When the temperature drops too low, the nylon melt viscosity and surface tension increase, resulting in reduced adhesion between the polyester and nylon fibers during fusion, causing interface separation, poor fiber cohesion, and easy formation of fuzz during stretching, making processing difficult.

[0015] This invention controls the temperature difference D during the fusion of polyester and nylon melts within a set range, ensuring a stable temperature difference between the two materials, preventing fluctuations in melt viscosity and surface tension. This prevents one melt from excessively wetting the other and encroaching on the other's shrinkage space during fusion. The two melts maintain a certain adhesive force, preventing interface separation and forming a stable cross-sectional configuration while preserving the continuity of the filaments along their length.

[0016] As a preferred technical solution:

[0017] The method described above for improving the quality of fine denier split polyester-nylon composite yarn has the following specifications: fine denier split polyester-nylon composite yarn has a specification of 22~55 dtex / 12~48f and a single filament fineness of <2.3 dtex.

[0018] The method described above for improving the quality of fine denier split polyester-nylon composite yarn has the following characteristics: the intrinsic viscosity of polyester is 0.6~0.68 dL / g, and the melting point is 255~265℃; the relative viscosity of nylon melt is 2.4~2.75, and the melting point is 220~235℃.

[0019] The method described above for improving the quality of fine denier split polyester-nylon composite yarn, wherein the value of D ranges from 5 to 25°C.

[0020] As described above, a method for improving the quality of fine denier split polyester-nylon composite yarn is described, wherein the polyester main box and the nylon secondary box are connected left and right by a heat insulation layer to form a cubic composite spinning box;

[0021] The polyester main box is an L-shaped box formed by connecting the polyester main box A on the left and the polyester main box B on the right. Both polyester main box A and polyester main box B are cubic structures. The lower surfaces of polyester main box A and polyester main box B are on the same horizontal plane.

[0022] The nylon sub-box is an L-shaped box formed by connecting the nylon sub-box B on the left and the nylon sub-box A on the right. Both the nylon sub-box A and the nylon sub-box B are cubic structures, and the upper surface of the nylon sub-box B and the upper surface of the nylon sub-box A are on the same horizontal plane.

[0023] That is, along the left and right direction of the composite spinning box, the cross-section of the polyester main box and the nylon auxiliary box are both L-shaped, and together they form a rectangular structure.

[0024] As described above, a method for improving the quality of fine denier split polyester-nylon composite yarn is provided with a component groove on the lower surface of the polyester main box body. A portion of the bottom area of ​​the component groove is a heat insulation layer on the lower surface of the nylon auxiliary box body B. The component groove is used to install the spinneret assembly.

[0025] The composite spinning box is equipped with a nylon connection port. One end of the nylon connection port is located on the bottom surface inside the nylon sub-box B, and the other end of the nylon connection port is located at the bottom of the component groove. The nylon connection port is used to connect the inside of the component groove with the inside of the nylon sub-box.

[0026] The spinneret assembly includes, from top to bottom, a top cover, a sand cup, a distribution plate, and a spinneret;

[0027] The top cover has through hole I and through hole II; a sleeve I is installed inside through hole II; sleeve I is a hollow structure with openings at both ends, and each end of sleeve I is individually fixedly connected to one end of through hole II, thus forming a jacket structure I; Figure 3 As shown, the only difference between the cover of the prior art and the present invention is that the cover does not have the jacket structure I.

[0028] The sand cup has two internal cavities, denoted as Sand Cup Cavity I and Sand Cup Cavity II. Inside Sand Cup Cavity II is a sleeve II. Sleeve II is a hollow structure open at both ends, with each end of sleeve II individually fixedly connected to one end of Sand Cup Cavity II, thus forming a jacket structure II. Figure 5 As shown, the only difference between the prior art sand cup and the present invention is that the latter does not have a jacket structure II.

[0029] The distribution plate is equipped with nylon melt channels and polyester melt channels; the inner wall of the nylon melt channel is equipped with a heat-insulating coating.

[0030] Through hole I, sand cup inner cavity I, and polyester melt channel are connected sequentially from top to bottom to form a total polyester melt channel, through which polyester melt flows;

[0031] The interior of sleeve I, the interior of sleeve II, and the nylon melt channel are connected sequentially from top to bottom to form the nylon melt general channel, through which the nylon melt flows;

[0032] Jacket structure I, jacket structure II, and heat insulation coating are all used to reduce the interference of polyester main box temperature and polyester melt temperature on nylon melt in spinneret assembly.

[0033] As described above, a method for improving the quality of fine denier split polyester-nylon composite yarn includes a distribution plate comprising a first distribution plate, a second distribution plate, and a third distribution plate connected from top to bottom. The first distribution plate, second distribution plate, third distribution plate, and spinneret are all made of stainless steel. Stainless steel has a heat transfer coefficient of 14~19 W / (m·K), while carbon steel has a heat transfer coefficient of 45~50 W / (m·K). Although the heat transfer coefficient of stainless steel is lower than that of carbon steel, which can reduce heat transfer, the distribution plate has many branched channels, narrow channels, and is mainly distributed in an array, making heat transfer easier. Figure 7 The diagram shows the positions of the distribution plate and spinneret in the prior art. The difference of this invention is that by adding a heat-insulating coating in the nylon channel of the distribution plate, the high temperature transferred from the main box to the nylon melt is reduced.

[0034] Temperature sensor I is installed in the nylon channel above the first distribution plate to detect the temperature of the nylon melt when it first enters the first distribution plate after leaving the sand cup. Temperature sensor II is installed in a single hole of the spinneret to detect the temperature when the polyester and nylon melts first enter the spinneret and fuse.

[0035] Temperature difference testing method:

[0036] When the polyester and nylon melts fill the entire assembly and are extruded together from the spinneret, the polyester metering pump is turned off, and the temperature sensor measures the temperature of the nylon melt just as it enters the spinneret. Then, the nylon metering pump is turned off again, and the polyester metering pump is turned on, with the temperature sensor again measuring the temperature of the polyester melt just as it enters the spinneret. The difference between the two temperatures is then calculated.

[0037] The method described above for improving the quality of fine denier split polyester-nylon composite yarn uses an Al2O3 ceramic heat insulation coating, which can withstand temperatures above 1200℃ and has a heat transfer coefficient of 8.7 W / (m·k), which is lower than that of stainless steel.

[0038] As described above, a method for improving the quality of fine denier split polyester-nylon composite yarn is provided in which a polyester metering pump is installed on the polyester main box, and the output end of the polyester metering pump is connected to the upper opening of through hole I through a connecting pipe.

[0039] The nylon auxiliary housing is equipped with a nylon metering pump. The output end of the nylon metering pump is connected to one end of a connecting pipe, and the other end of the connecting pipe passes through the nylon connection port and is connected to the upper end of the sleeve I.

[0040] As described above, in a method for improving the quality of fine denier split polyester-nylon composite yarn, the shape inside sleeve I is exactly the same as the shape inside through hole I; the shape inside sleeve II is exactly the same as the shape inside the inner cavity I of the sand cup.

[0041] The outer surface of sleeve I is equidistant from the inner wall of through hole II, and the outer surface of sleeve II is equidistant from the inner wall of sand cup cavity II.

[0042] As described above, in a method for improving the quality of fine denier split polyester-nylon composite yarn, the spinneret assembly further includes ring I, ring II, ring III, and ring IV.

[0043] Rings I, II, III, and IV are all placed horizontally;

[0044] The upper end of sleeve I is fixedly connected to the upper end of through hole II via ring I, and the lower end of sleeve I is fixedly connected to the lower end of through hole II via ring II.

[0045] The upper end of sleeve II is fixedly connected to the upper end of the inner cavity II of the sand cup via ring III, and the lower end of sleeve II is fixedly connected to the lower end of the inner cavity II of the sand cup via ring IV.

[0046] As described above, in a method for improving the quality of fine denier split polyester-nylon composite yarn, the spinneret assembly further includes a housing, a disc spring, and a locking ring.

[0047] The spinneret, distribution plate, sand cup, and top cover are placed in the housing from bottom to top. The housing is fixed in place by cooperating with a butterfly spring and a locking ring. The shape and structure of the housing, butterfly spring, and locking ring, as well as their connection with the top cover, are all existing technologies.

[0048] Invention principle:

[0049] Split-type polyester-nylon composite yarn is produced by polyester and nylon melts entering from different channels along the lower edge of the third distribution plate. They fuse in the spinneret orifices to form a unique cross-sectional shape. Each filament contains both polyester and nylon components, with the nylon shaped like a starfish. The polyester is divided into six arc-shaped triangles, nestled between the star's points. The overall structure of the polyester and nylon monofilaments is circular. Compared to other types, split-type polyester-nylon composite yarn requires a fiber-opening step in post-processing. This involves using physical or chemical methods to separate the polyester and nylon fibers into finer, multi-shaped fibers, resulting in a fabric with superior tactile and visual effects. For successful fiber opening in subsequent processes, and to ensure high dyeing uniformity (i.e., uniform shape of the six polyester arc-shaped triangles), a clearer interface is required during fusion of the two melts. One melt should not be excessively wetted, encroaching on the shrinkage space of the other. The two melts also require a certain degree of adhesion. If the adhesion is too low, they will separate with slight tension during production (premature fiber opening), affecting fiber strength and causing fuzz. When the two melts fuse, the viscosity fluctuates, and the surface tension of the melt changes. This affects the ratio of the two components in the cross-section and the continuity of the filaments along the length, especially for fine denier filaments. The resulting unstable cross-sectional deformation has a greater impact on product quality.

[0050] Because nylon has a starfish-like structure and a large specific surface area, while polyester has six arc-shaped triangles, each with two faces in contact with the nylon, this type of nylon-polyester contact surface is significantly increased compared to other types. Before fusion, the nylon melt undergoes sufficient high-temperature heat transfer. When the temperature difference is too small (nylon temperature too high), the nylon melt viscosity and surface tension decrease, leading to excessive wetting of the polyester melt and encroachment on the nylon melt's contraction space. This causes the polyester fibers (arc-shaped triangles) to adhere, resulting in an unclear interface and a deformed cross-section. When nylon undergoes prolonged thermal degradation due to overheating, the uniformity of the nylon melt deteriorates, severely affecting its dispersion morphology. This results in a more chaotic cross-sectional configuration during fusion with polyester, affecting the continuity of the filaments along their length, and impairing spinnability, leading to breakage. However, if the temperature difference is too large (the nylon temperature is too low), the nylon melt viscosity and surface tension increase, leading to a decrease in the adhesion between polyester and nylon during fusion. This can also cause cross-sectional deformation, interface separation, poor fiber cohesion, and the formation of fuzz during subsequent stretching, making processing difficult. Therefore, compared to producing other types of polyester-nylon composite yarns, the production of split-type polyester-nylon composite yarns requires controlling the fusion temperature of the two melts within a specific range.

[0051] Extensive experimental verification has been conducted using the formula designed in this invention. By controlling the temperature difference D between the nylon melt and the polyester melt when they enter the spinneret, it is possible to ensure good melt uniformity and stable surface tension when the two melts are fused, thus obtaining polyester-nylon composite yarn with a clear interface and no cross-sectional deformation.

[0052] Reference 3 (Research on Calculation Method of Polymer Melt Surface Tension [J]. Chemical Engineering and Equipment, 2012(9):2.) mentions that the surface tension of polymer melt during polymer blending will affect the dispersion morphology of the polymer. Polymers are prone to oxidative degradation when melting at higher temperatures, so the experimental testing of polymer melt surface tension is difficult and not easy to measure accurately. This indicates that the surface tension will fluctuate after oxidative degradation, affecting the dispersion morphology of the melt. It also indicates that the test of melt is inaccurate during temperature fluctuations. Testing the temperature difference when the two melts are fused is more accurate than testing the temperature difference when the spinneret is exposed and when it is in the box. Moreover, by controlling the temperature difference when the two melts are fused, it is easier to obtain fine denier split polyester-nylon composite yarn with a clear interface and no cross-sectional deformation. The reasons are as follows:

[0053] (1) The mass of the two melts at the time of fusion determines the shape of the fusion cross section of the two components. When the two melts enter the spinneret, they undergo sufficient heat conduction and are closer to the fusion position of the two melts. That is, the temperature difference between the two melts when they enter the spinneret is closer to the temperature difference when they fuse than the temperature difference when they are in the box. Controlling the temperature difference when entering the spinneret can better solve the problem of mass reduction caused by cross section deformation.

[0054] (2) The two melts have their own independent insulation in the box, and the temperature settings of each box can maintain the best quality of their respective melts. When the nylon component is subjected to high temperature transfer from the main box in the module, if the temperature of the nylon box is reduced in advance to lower the temperature of the nylon melt, then: the temperature of the nylon box is supplied by the nylon heat medium furnace, and the heat medium continues to be supplied to the melt conveying pipeline after passing through the box. That is, when the temperature of the nylon box is adjusted, the quality of the nylon melt is affected by the adjustment of the box temperature during its long-distance pipeline transport after it comes out of the screw; the adjustment of the box temperature is limited, and when the nylon melt enters the module, it conducts heat rapidly, so that the adjustment of the box temperature is offset before the two components fuse.

[0055] (3) Q = -KtS (T2-T1) / d, where K is the thermal conductivity, t is the conduction time, S is the heat transfer area, T2 is the temperature of the high-temperature surface, T1 is the temperature of the low-temperature surface, and d is the distance between the heat transfer surfaces. The melt undergoes sufficient heat conduction with the heating medium in the box and the conveying pipe, and the temperature change of the melt is very small as time t increases. However, the heat conduction of nylon melt in the module is greatly affected by the conduction time t due to the large temperature difference between it and the main box. When producing different types of fibers, the residence time of the melt in the module is different. For example, when the same module produces 30dtex and 90dtex fibers, the residence time t of the melt in the module increases by two times. Assuming that other variables remain unchanged, the heat conduction Q also increases by two times. Therefore, the temperature difference between the two components is smaller when producing fine denier fibers than coarse denier fibers. When the temperature difference exceeds a certain range, the fusion cross section of the two components deforms.

[0056] This invention increases the heat transfer surface distance d and reduces the thermal conductivity K by adding a jacket structure and a heat insulation coating. This reduces the amount of heat conduction from the main housing to the nylon melt, controls the temperature difference when the polyester and nylon melts fuse, reduces cross-sectional deformation, and improves product quality.

[0057] Beneficial effects:

[0058] (1) A method for improving the quality of fine denier split polyester-nylon composite yarn of the present invention, by controlling the temperature difference between the nylon melt and the polyester melt when entering the spinneret, can ensure that the two melts have good melt uniformity and stable surface tension when they are fused, and can obtain polyester-nylon composite yarn with clear interface and no cross-section deformation.

[0059] (2) The present invention provides a method for improving the quality of fine denier split polyester-nylon composite yarn. The method is simple, reduces cross-sectional deformation, and improves product quality. Attached Figure Description

[0060] Figure 1 A schematic diagram showing the melt flow direction within the box for the one-step production of fine denier split polyester-nylon composite yarn;

[0061] Figure 2 This is a cross-sectional view of the split-type polyester-nylon composite yarn assembly of the present invention;

[0062] Figure 3 This is a schematic diagram of the component cover in the prior art;

[0063] Figure 4 This is a schematic diagram of the component cover of the present invention;

[0064] Figure 5 A schematic diagram of a component sand cup in the prior art;

[0065] Figure 6 This is a schematic diagram of the sand cup component of the present invention;

[0066] Figure 7 A schematic diagram showing the positions of the spinneret and spinneret in existing technology;

[0067] Figure 8 This is a schematic diagram of the cross-section of a split-type polyester-nylon composite yarn monofilament when it is in normal condition.

[0068] Figure 9 This is a schematic diagram of the cross-section of a split-type polyester-nylon composite yarn after the single filament is fully opened under normal conditions.

[0069] Figure 10 This is a schematic diagram of the fiber cross-section when a split-type polyester-nylon composite yarn monofilament is abnormal, as shown in Comparative Example 1.

[0070] Figure 11 This is a schematic diagram of the fiber cross-section after complete splitting of a split-type polyester-nylon composite yarn monofilament when an abnormality occurs in Comparative Example 1.

[0071] Figure 12 When producing fine denier split polyester-nylon composite yarn using components with d2 of 1mm and d1 of 3mm, the Q value generated by the computer is... b - (Ta3-Tb3) curve;

[0072] Among them, 1-sub-box, 2-main box, 3-insulation layer, 4-nylon metering pump, 5-polyester metering pump, 6-connecting pipe connected to the output end of the nylon metering pump, 7-connecting pipe connected to the output end of the polyester metering pump, 8-component, 9-nylon melt main channel, 10-polyester melt main channel, 11-sand cup, 12-first distribution plate, 13-second distribution plate, 14-third distribution plate, 15-spinneret, 16-spinneret hole, 17-jacket structure I, 18-jacket structure II, 19-polyester, 20-nylon, 21-temperature sensor I, 22-temperature sensor II. Detailed Implementation

[0073] 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.

[0074] The testing methods involved in the performance indicators of this invention are as follows:

[0075] (1) Fiber cross section detection method: The RX50M microscope and the matching fiber cross section detection system produced by Ningbo Sunny Optical Co., Ltd. were used for detection.

[0076] (2) Method for opening split polyester-nylon composite yarn: Put the finished fiber into a 1.5wt% NaOH aqueous solution and heat it to boiling for 45 minutes. After taking it out and drying it, check the fiber cross-section.

[0077] (3) The fiber opening rate of split polyester-nylon composite yarn = the number of monofilaments completely separated from the nylon component by polyester / the total number of polyester monofilaments × 100%.

[0078] A device for preparing fine denier split-type polyester-nylon composite yarn, wherein the spinning box includes a polyester main box and a nylon auxiliary box; the polyester main box and the nylon auxiliary box are connected left and right by a heat insulation layer to form a cubic composite spinning box;

[0079] like Figure 1 , Figure 2 As shown, the polyester main box is an L-shaped box composed of polyester main box A on the left and polyester main box B on the right. Both polyester main box A and polyester main box B are cubic structures. The lower surfaces of polyester main box A and polyester main box B are on the same horizontal plane.

[0080] The nylon sub-box is an L-shaped box formed by connecting the nylon sub-box B on the left and the nylon sub-box A on the right. Both the nylon sub-box A and the nylon sub-box B are cubic structures, and the upper surface of the nylon sub-box B and the upper surface of the nylon sub-box A are on the same horizontal plane.

[0081] The lower surface of the polyester main housing is provided with a component groove, and part of the bottom area of ​​the component groove is the heat insulation layer of the lower surface of the nylon secondary housing B; the component groove is used to install the spinneret assembly;

[0082] The composite spinning box is equipped with a nylon connection port. One end of the nylon connection port is located on the bottom surface inside the nylon sub-box B, and the other end of the nylon connection port is located at the bottom of the component groove. The nylon connection port is used to connect the inside of the component groove with the inside of the nylon sub-box.

[0083] The spinneret assembly includes, from top to bottom, an upper cover, a sand cup 11, a distribution plate, a spinneret 15, a ring I, a ring II, a ring III, a ring IV, a housing, a disc spring, and a locking ring;

[0084] like Figure 4 As shown, the top cover is provided with through hole I and through hole II; a sleeve I is provided inside through hole II; the sleeve I is a hollow structure with openings at both ends, and each end of the sleeve I is individually fixedly connected to one end of through hole II, thereby forming a jacket structure I17.

[0085] like Figure 6 As shown, the sand cup has two inner cavities, referred to as sand cup cavity I and sand cup cavity II respectively; a sleeve II is provided inside sand cup cavity II; the sleeve II is a hollow structure with open ends, and each end of the sleeve II is fixedly connected to one end of sand cup cavity II, thus forming a jacket structure II 18.

[0086] The distribution plate includes a first distribution plate 12, a second distribution plate 13, and a third distribution plate 14 connected from top to bottom; the distribution plate is provided with a nylon melt channel and a polyester melt channel; the inner wall of the nylon melt channel is provided with a heat-insulating coating.

[0087] Temperature sensor I 21 is installed in the nylon melt channel above the first distribution plate to detect the temperature of the nylon melt when it enters the first distribution plate after leaving the sand cup; the melt is split in a ring from the first distribution plate, and the flow is squeezed and isolated in its own fine channels. It only begins to converge and flow into the single hole of each spinneret at the lower edge of the third distribution plate. Temperature sensor II 22 is installed in the single hole of the spinneret to detect the temperature of the polyester and nylon melts when they merge into the spinneret hole 16.

[0088] Through hole I, sand cup inner cavity I and polyester melt channel are connected sequentially from top to bottom to form polyester melt general channel 10, which is used for polyester melt to flow through;

[0089] The interior of sleeve I, the interior of sleeve II, and the nylon melt channel are connected sequentially from top to bottom to form the nylon melt general channel 9, through which the nylon melt flows;

[0090] Rings I, II, III, and IV are all placed horizontally;

[0091] The upper end of sleeve I is fixedly connected to the upper end of through hole II via ring I, and the lower end of sleeve I is fixedly connected to the lower end of through hole II via ring II.

[0092] The upper end of sleeve II is fixedly connected to the upper end of the inner cavity II of the sand cup via ring III, and the lower end of sleeve II is fixedly connected to the lower end of the inner cavity II of the sand cup via ring IV.

[0093] The spinneret 15, the distribution plate, the sand cup 11, and the top cover are placed in the housing from bottom to top. The housing is fixed in place by cooperating with a butterfly spring and a locking ring.

[0094] In this invention, the formula for calculating the temperature difference D between the nylon melt and the polyester melt when they enter the spinneret is as follows:

[0095] ;

[0096] In the formula, Tm a Tm is the melting point of polyester. b Tm is the melting point of nylon. a +A represents the chamber temperature setting range for the polyester melt. A refers to the difference between the chamber temperature of the polyester melt and the melting point of polyester. The value of A ranges from 25 to 30℃. Tm b +B represents the set temperature range of the nylon melt chamber, where B is the difference between the chamber temperature of the nylon melt and the melting point of the nylon. The value of B ranges from 30 to 35℃. K is a coefficient, and the value of K ranges from 0.45 to 0.55.

[0097] When the melting point of polyester is 255~265℃ and the melting point of nylon is 220~235℃, the value of D ranges from 5 to 25℃.

[0098] The specific steps for controlling the temperature difference mentioned above are as follows:

[0099] Step 1: The temperature of the nylon melt when it reaches the spinneret through the distribution plate is Tb3. By adding a heat-insulating coating with a lower heat transfer coefficient to the nylon channel, the thickness of the heat-insulating coating is d2. By adjusting the thickness of d2, Tb3 is reduced.

[0100] Step 2: Add a jacket structure II to the nylon sand cup to control the temperature Tb2 when the nylon melt leaves the sand cup and just enters the distribution plate. By selecting different thicknesses of the jacket structure II thickness d1, Tb2 can be reduced.

[0101] Temperature sensors detect Ta3 (Ta3: the temperature of the polyester melt when it enters the spinneret), Tb2, and Tb3. Through continuous adjustment and data analysis, the values ​​of d2 and d1 are determined, ultimately ensuring that the temperature difference Ta3-Tb3 when the two melts fuse is within the specified range.

[0102] When producing polyester-nylon composite yarns of different specifications and proportions, the amount of nylon extruded, Q... b Unlike ρV, which are both quantitative, Q can be used. b To characterize the residence time t, the computer calculates the data and generates Q. b- The (Ta3-Tb3) curve is used to determine the number of split polyester-nylon composite yarns that can be produced simultaneously using this component when both d2 and d1 are constant. b The range of (the amount of nylon extruded).

[0103] The specific adjustment process is as follows:

[0104] If step 1 is performed without step 2 (i.e., the nylon sand cup is not fitted with jacket structure II, and only the thickness d2 of the heat insulation coating on the distribution plate is adjusted), then 5℃ < Ta3 - Tb3 < 25℃ can be achieved. In this case, the value of d2 is determined and the adjustment is completed.

[0105] If only step 1 is performed and the coating thickness reaches the maximum required thickness (1mm), but still does not meet the requirement of 5℃ < Ta3 - Tb3 < 25℃, then step 1 uses the maximum coating thickness, and step 2 is also required: replace the nylon abrasive cup with one featuring a jacketed structure II. After steps 1 and 2, analyze the computer-detected Ta3, Tb2, and Tb3 data, select a suitable jacketed structure II thickness d1, ensuring 5℃ < Ta3 - Tb3 < 25℃, then determine the values ​​of d1 and d2, and the adjustment is complete.

[0106] Once the values ​​of d1 and d2 of this component are determined, Q is adjusted. b The values ​​correspond to Ta3, Tb2, and Tb3, and the computer calculates and generates Q. b - (Ta3-Tb3) curve, such that 5℃ < Ta3-Tb3 < 25℃, derive Q from the curve. b The range of values ​​for , that is: using components with fixed values ​​of d1 and d2, Q can be produced simultaneously. b Split-type polyester-nylon composite yarns within this range.

[0107] Example 1

[0108] A method for improving the quality of fine denier split polyester-nylon composite yarn, using the above-mentioned preparation apparatus, is as follows:

[0109] The preparation process of fine denier split polyester-nylon composite yarn is as follows: polyester melt and nylon melt are transported into the main polyester chamber and the secondary nylon chamber through their respective pipelines. The intrinsic viscosity of polyester is 0.68 dL / g, and the melting point is 265℃; the relative viscosity of nylon melt is 2.75, and the melting point is 235℃. The two chambers are independently temperature controlled. Metering pumps located in their respective chambers meter the two melts before they enter the same spinning assembly located in the main polyester chamber. In the spinning assembly, the polyester melt and nylon melt enter their respective sand cups through their respective channels on the assembly cover, are pressurized and filtered, and then enter the distribution plate. After passing through the distribution plate, the yarn is then processed according to the specified parameters. The nylon filaments converge and fuse, and are extruded into filaments from the spinneret. The temperature difference D between the nylon melt and the polyester melt when entering the spinneret is controlled to be 11℃ (since 55dtex / 48f is not very fine for fine denier yarn, a high box temperature is not required to increase the fluidity of the melt, so A is set to 25℃ and B to 30℃; since there are many filaments, the polyester melt channel and the nylon melt channel in the distribution plate are close, resulting in more heat transfer, so a smaller K value is easier to achieve, hence K is set to 0.45); finally, the filaments are sequentially cooled, oiled, stretched, heat-set, and wound to form a fine denier filament-type polyester-nylon composite yarn.

[0110] The spinning process parameters are as follows: the thickness of the heat insulation coating d2 is 1mm, the thickness of the jacket structure II of the nylon sand cup d1 is 2mm, the cooling temperature is 19℃, the oiling rate is 1.05%, the stretching ratio is 3.42 times, the heat setting temperature is 130℃, the temperature of the polyester main box is 290℃, the temperature of the nylon auxiliary box is 265℃, the monomer suction pressure is 0.5bar, the side blowing wind speed is 0.4m / min, and the winding speed is 3600m / min.

[0111] like Figures 8-9 As shown, the final fine denier split polyester-nylon composite yarn has a specification of 55 dtex / 48f and a single filament fineness of 1.15 dtex. The nylon content in the fine denier split polyester-nylon composite yarn is 30 wt%, and polyester 19 is in the form of 6 arc triangles, with two faces of each arc triangle in contact with nylon 20. The nylon output is 5.94 g / min. After opening, the opening rate of the fine denier split polyester-nylon composite yarn is 99.3%, the dyeing M rate is 99.8%, and the fuzz rate is 0.35%.

[0112] Comparative Example 1

[0113] A method for improving the quality of polyester-nylon composite yarn is basically the same as in Example 1, except that it employs the following method: Figure 3 , Figure 5 The components of the prior art are shown.

[0114] During production, the polyester metering pump was turned on, and the nylon metering pump was turned off. The temperature of the polyester melt just entering the spinneret was measured to be 275℃. The polyester metering pump was turned off, and the nylon metering pump was turned on. The temperature of the nylon melt just entering the spinneret was measured to be 268℃. The temperature difference between the polyester and nylon melts entering the spinneret was 7℃.

[0115] The final split-type polyester-nylon composite yarn has a specification of 55 dtex / 48f, a fiber opening rate of 94.3% after fiber opening, a dyeing M rate of 91.3%, and a fuzz rate of 0.55%.

[0116] Comparing Comparative Example 1 with Example 1, it can be found that the fiber opening rate of Example 1 increased by 5.0%, the dyeing M rate increased by 8.5%, and the fuzz rate increased by 0.2%. This is because when producing split polyester-nylon composite yarn with a specification of 55dtex / 48f, the fibers are finer, the nylon melt flow rate is lower, and the residence time in the component is longer, resulting in a decrease in the viscosity and surface tension of the nylon melt. This leads to excessive wetting of the polyester melt, which squeezes the shrinkage space of the nylon melt, causing the polyester (arc triangular) fibers to stick together, making it difficult to open the finished fiber and affecting the dyeing uniformity.

[0117] like Figure 10 As shown, when using existing technology to produce fine denier split polyester-nylon composite yarn, the nylon melt flow rate is too low, and the residence time in the main channel of the component is too long. It is subjected to sufficient heat transfer from the high temperature of the polyester main box and the high temperature of the polyester melt. When the two melts reach the lower edge of the third spinneret and fuse, the temperature difference becomes smaller, the temperature of the nylon melt rises, resulting in a decrease in the viscosity and surface tension of the nylon melt. The excessive wetting of the polyester melt squeezes the shrinkage space of the nylon melt, causing some polyester (circular arc triangle) to stick together, forming a deformed cross section with an imbalance of polyester and nylon components.

[0118] like Figure 11 As shown, when using existing technology to produce fine denier split polyester-nylon composite yarn, after the cross-section is deformed, the polyester fibers that stick together cannot be split into uniform arc triangles during the subsequent fiber opening process, which affects the dyeing uniformity.

[0119] Example 2

[0120] A method for improving the quality of fine denier split polyester-nylon composite yarn, using the above-mentioned preparation apparatus, is as follows:

[0121] The preparation process of fine denier split polyester-nylon composite yarn is as follows: polyester melt and nylon melt are transported into the main polyester chamber and the secondary nylon chamber through their respective pipelines. The intrinsic viscosity of polyester is 0.68 dL / g, and its melting point is 265℃; the relative viscosity of nylon melt is 2.75, and its melting point is 235℃. The two chambers are independently temperature-controlled. Metering pumps located in their respective chambers meter the two melts before they enter the same spinning assembly located in the main polyester chamber. In the spinning assembly, the polyester melt and nylon melt enter their respective sand cups through their respective channels on the assembly cover, are pressurized and filtered, and then enter the distribution plate. After passing through the distribution plate, the fibers converge and fuse according to the designed slit shape, and are extruded into filaments from the spinneret. The temperature difference D between the nylon melt and the polyester melt when entering the spinneret is controlled to be 12.5℃ (since 55dtex / 24f is not very fine among fine denier yarns, a high box temperature is not required to increase the flow state of the melt, so A is 25℃ and B is 30℃; the number of single filaments is moderate, the distance between the polyester melt channel and the nylon melt channel in the distribution plate is moderate, and the heat transfer is moderate, so K is 0.5); finally, the filaments are successively cooled, oiled, stretched, heat-set and wound to form fine denier slit-type polyester-nylon composite yarn;

[0122] The spinning process parameters are as follows: cooling temperature is 19℃, oiling rate is 1.08%, stretching ratio is 3.29 times, heat setting temperature is 130℃, polyester main box temperature is 290℃, nylon auxiliary box temperature is 265℃, monomer suction pressure is 0.5 bar, side blowing speed is 0.4 m / min, and winding speed is 3500 m / min.

[0123] like Figure 12 As shown, when the temperature of the polyester main chamber is 290℃, the temperature of the nylon auxiliary chamber is 265℃, the thickness of the heat insulation coating d2 reaches its maximum value of 1mm, and the thickness d1 of the jacket structure II of the nylon sand cup is 3mm, the nylon discharge rate Q is adjusted. b Values, detecting Ta3 and Tb3 values, generating Q b - (Ta3-Tb3) curve, when the curve is within the rectangular frame, 11℃ < Ta3-Tb3 < 14℃ (K value ranges from 0.45 to 0.55), corresponding to Q b The value is 1.7~2.3 g / min, which means that components with d2 of 1 mm and d1 of 3 mm can be used to produce split polyester-nylon composite yarn with a nylon output of 1.7~2.3 g / min, meeting the requirement that the cross-section does not deform.

[0124] The final fine denier split polyester-nylon composite yarn has a specification of 55 dtex / 24f and a single filament fineness of 2.29 dtex; the nylon content in the fine denier split polyester-nylon composite yarn is 10 wt%; the nylon output is 1.93 g / min; after opening, the opening rate of the fine denier split polyester-nylon composite yarn is 99.1%, the dyeing M rate is 99.6%, and the fuzz rate is 0.43%.

[0125] Example 3

[0126] A method for improving the quality of fine denier split polyester-nylon composite yarn, using the above-mentioned preparation apparatus, is as follows:

[0127] The preparation process of fine denier split polyester-nylon composite yarn is as follows: polyester melt and nylon melt are transported into the main polyester chamber and the secondary nylon chamber through their respective pipelines. The intrinsic viscosity of polyester is 0.68 dL / g, and the melting point is 265℃; the relative viscosity of nylon melt is 2.75, and the melting point is 235℃. The two chambers are independently temperature controlled. Metering pumps located in their respective chambers meter the two melts and then they enter the same spinning assembly located in the main polyester chamber. In the spinning assembly, the polyester melt and nylon melt enter their respective sand cups through their respective channels on the assembly cover, are pressurized and filtered, and then enter the distribution plate. After passing through the distribution plate, the nylon melt converges and fuses according to the designed slit shape, and is extruded into filaments from the spinneret. The temperature difference D between the nylon melt and the polyester melt when entering the spinneret is controlled to be 13.5℃ (since 22dtex / 24f is very fine in fine denier yarn, a higher box temperature is required to increase the flow state of the melt, so A is 30℃ and B is 33℃; the number of single filaments is moderate, the distance between the polyester melt channel and the nylon melt channel in the distribution plate is moderate, and the heat transfer is moderate, so K is 0.5); finally, the filaments are cooled, oiled, stretched, heat-set and wound in sequence to obtain fine denier slit-type polyester-nylon composite yarn;

[0128] The spinning process parameters are as follows: the thickness of the heat insulation coating d2 is 1mm, the thickness of the jacket structure II of the nylon sand cup d1 is 4mm, the cooling temperature is 19℃, the oiling rate is 1.12, the stretching ratio is 3.54 times, the heat setting temperature is 124℃, the temperature of the polyester main box is 295℃, the temperature of the nylon auxiliary box is 268℃, the monomer suction pressure is 0.4bar, the side blowing wind speed is 0.28m / min, and the winding speed is 3000m / min.

[0129] The final fine denier split polyester-nylon composite yarn has a specification of 22 dtex / 24f and a single filament fineness of 0.92 dtex; the nylon content in the fine denier split polyester-nylon composite yarn is 20 wt%; the nylon output is 1.32 g / min; after opening, the opening rate of the fine denier split polyester-nylon composite yarn is 99.4%, the dyeing M rate is 99.7%, and the fuzz rate is 0.32%.

[0130] Example 4

[0131] A method for improving the quality of fine denier split polyester-nylon composite yarn, using the above-mentioned preparation apparatus, is as follows:

[0132] The preparation process of fine denier split polyester-nylon composite yarn is as follows: polyester melt and nylon melt are transported into the main polyester chamber and the secondary nylon chamber through their respective pipelines. The intrinsic viscosity of polyester is 0.6 dL / g, and the melting point is 255℃; the relative viscosity of nylon melt is 2.4, and the melting point is 220℃. The two chambers are independently temperature controlled. Metering pumps located in their respective chambers meter the two melts before they enter the same spinning assembly located in the main polyester chamber. In the spinning assembly, the polyester melt and nylon melt enter their respective sand cups through their respective channels on the assembly cover, are pressurized and filtered, and then enter the spinning process. After passing through the distribution plate, the fibers converge and fuse according to the designed slit shape, and are extruded into filaments from the spinneret. The temperature difference D between the nylon melt and the polyester melt when entering the spinneret is controlled to be 14.5℃ (since 33dtex / 36f is of moderate thickness among fine denier yarns, and the box temperature is moderate, A is set to 27℃ and B to 33℃; the number of single filaments is moderate, and the distance between the polyester melt channel and the nylon melt channel in the distribution plate is moderate, resulting in moderate heat transfer, so K is set to 0.5). Finally, the filaments are successively cooled, oiled, stretched, heat-set, and wound to form fine denier slit-type polyester-nylon composite yarn.

[0133] The spinning process parameters are as follows: the thickness of the heat insulation coating d2 is 1mm, the thickness of the jacket structure II of the nylon sand cup d1 is 3mm, the cooling temperature is 19℃, the oiling rate is 1.1, the stretching ratio is 3.36 times, the heat setting temperature is 128℃, the temperature of the polyester main box is 282℃, the temperature of the nylon auxiliary box is 253℃, the monomer suction pressure is 0.45bar, the side blowing wind speed is 0.3m / min, and the winding speed is 3200m / min.

[0134] The final fine denier split polyester-nylon composite yarn has a specification of 33 dtex / 36f and a single filament fineness of 0.92 dtex; the nylon content in the fine denier split polyester-nylon composite yarn is 20 wt%; the nylon output is 2.11 g / min; after opening, the opening rate of the fine denier split polyester-nylon composite yarn is 99.3%, the dyeing M rate is 99.7%, and the fuzz rate is 0.25%.

[0135] Example 5

[0136] A method for improving the quality of fine denier split polyester-nylon composite yarn, using the above-mentioned preparation apparatus, is as follows:

[0137] The preparation process of fine denier split polyester-nylon composite yarn is as follows: polyester melt and nylon melt are transported into the main polyester chamber and the secondary nylon chamber through their respective pipelines. The intrinsic viscosity of polyester is 0.6 dL / g, and the melting point is 255℃; the relative viscosity of nylon melt is 2.4, and the melting point is 220℃. The two chambers are independently temperature controlled. Metering pumps located in their respective chambers meter the two melts before they enter the same spinning assembly located in the main polyester chamber. In the spinning assembly, the polyester melt and nylon melt enter their respective sand cups through their respective channels on the assembly cover, are pressurized and filtered, and then enter the distribution plate. After passing through the distribution plate, they are then processed according to... The designed slit shapes converge and fuse, and are extruded into filaments from the spinneret. The temperature difference D between the nylon melt and the polyester melt when entering the spinneret is controlled to be 16.5℃ (since 22dtex / 12f is very fine in fine denier yarn, a higher box temperature is required to increase the fluidity of the melt, so A is 30℃ and B is 35℃; since the number of single filaments is small, the distance between the polyester melt channel and the nylon melt channel in the distribution plate is large, resulting in less heat transfer, so even if K is a large value, it is easy to achieve, so K is 0.55); finally, the filaments are successively cooled, oiled, stretched, heat-set and wound to form fine denier slit-type polyester-nylon composite yarn;

[0138] The spinning process parameters are as follows: the thickness of the heat insulation coating d2 is 1mm, the thickness of the jacket structure II of the nylon sand cup d1 is 3mm, the cooling temperature is 19℃, the oiling rate is 1.15%, the stretching ratio is 3.65, the heat setting temperature is 124℃, the temperature of the polyester main box is 285℃, the temperature of the nylon auxiliary box is 255℃, the monomer suction pressure is 0.4bar, the side blowing wind speed is 0.28m / min, and the winding speed is 2800m / min.

[0139] The final fine denier split polyester-nylon composite yarn has a specification of 22 dtex / 12f and a single filament fineness of 1.83 dtex; the nylon content in the fine denier split polyester-nylon composite yarn is 30 wt%; the nylon output is 1.85 g / min; after opening, the opening rate of the fine denier split polyester-nylon composite yarn is 99.6%, the dyeing M rate is 99.8%, and the fuzz rate is 0.21%.

[0140] Table 1 below compares the residence time of nylon melt in the components for different specifications of polyester-nylon composite yarns (the finer the fiber, the more suitable for low machine speed) when the polyester-nylon ratio is 70:30, as measured in actual production:

[0141] Table 1

[0142]

[0143] As can be seen from the comparison in Table 1 above, there is a significant difference in the residence time of the nylon melt within the module when producing polyester-nylon composite yarns of different specifications. For 22 dtex yarns, the residence time is 1160 seconds, while for 198 dtex yarns, it is only 75 seconds. When producing coarse denier yarns, the high melt flow rate means that the two melts do not have enough time for sufficient heat transfer, and both retain their respective melt temperatures from their original chamber temperatures, resulting in a large temperature difference upon fusion. However, when producing fine denier yarns, the two melts have a sufficiently long heat transfer time, resulting in a smaller temperature difference upon fusion. The temperatures at which polyester and nylon fuse after sufficient heat transfer are shown in Table 2 below, where the polyester chamber temperature is 290℃ and the nylon chamber temperature is 265℃.

[0144] Table 2

[0145]

[0146] The effects to be achieved by using the technical solution of this invention on fine denier polyester-nylon composite yarn are shown in Table 3 below.

[0147] Table 3

[0148]

Claims

1. A method for improving the quality of fine denier split polyester-nylon composite yarn, wherein the nylon content in the fine denier split polyester-nylon composite yarn is 10-30 wt%; the preparation process of the fine denier split polyester-nylon composite yarn is as follows: polyester melt and nylon melt are transported into a spinning box through their respective pipelines. The spinning box consists of a main polyester box and a secondary nylon box. Metering pumps located in their respective boxes meter the two melts and then they enter the same spinning assembly located in the main polyester box. In the spinning assembly, the polyester melt and nylon melt enter their respective sand cups through their respective channels on the assembly cover, are pressurized and filtered, and then enter a distribution plate. After passing through the distribution plate, they converge and fuse according to the designed split shape and are extruded into filaments from the spinneret. Finally, the filaments undergo cooling, oiling, stretching, heat setting, and winding to obtain the fine denier split polyester-nylon composite yarn; characterized in that: By controlling the temperature difference between the nylon melt and the polyester melt when they enter the spinneret to be D, the fine denier split-type polyester-nylon composite yarn prepared has a fiber opening rate >99%, a dyeing M rate >99.5%, and a fuzz rate <0.5% after fiber opening. ； In the formula, Tm a Tm is the melting point of polyester. b Tm is the melting point of nylon. a +A represents the chamber temperature setting range for the polyester melt, with A ranging from 25 to 30°C. Tm b +B represents the temperature setting range of the nylon melt chamber, with a value range of 30~35℃. K is a coefficient, with a value range of 0.45~0.

55.

2. The method for improving the quality of fine denier split polyester-nylon composite yarn according to claim 1, characterized in that, The specifications of fine denier split polyester-nylon composite yarn are 22~55 dtex / 12~48f, and the fineness of a single filament is <2.3 dtex.

3. The method for improving the quality of fine denier split polyester-nylon composite yarn according to claim 1, characterized in that, The intrinsic viscosity of polyester is 0.6~0.68 dL / g, and the melting point is 255~265℃; the relative viscosity of nylon melt is 2.4~2.75, and the melting point is 220~235℃.

4. The method for improving the quality of fine denier split polyester-nylon composite yarn according to claim 3, characterized in that, The value of D ranges from 5 to 25℃.

5. The method for improving the quality of fine denier split polyester-nylon composite yarn according to claim 1, characterized in that, A composite spinning box with a cubic structure is formed by connecting the polyester main box and the nylon secondary box through a heat insulation layer on the left and right sides. The polyester main box is an L-shaped box formed by connecting the polyester main box A on the left and the polyester main box B on the right. Both polyester main box A and polyester main box B are cubic structures. The lower surfaces of polyester main box A and polyester main box B are on the same horizontal plane. The nylon sub-box is an L-shaped box formed by connecting the nylon sub-box B on the left and the nylon sub-box A on the right. Both the nylon sub-box A and the nylon sub-box B are cubic structures, and the upper surface of the nylon sub-box B and the upper surface of the nylon sub-box A are on the same horizontal plane.

6. The method for improving the quality of fine denier split polyester-nylon composite yarn according to claim 5, characterized in that, The lower surface of the polyester main housing is provided with a component groove, and part of the bottom area of ​​the component groove is the heat insulation layer of the lower surface of the nylon secondary housing B; the component groove is used to install the spinneret assembly; The composite spinning box is equipped with a nylon connection port. One end of the nylon connection port is located on the bottom surface inside the nylon sub-box B, and the other end of the nylon connection port is located at the bottom of the component groove. The spinneret assembly includes, from top to bottom, a top cover, a sand cup, a distribution plate, and a spinneret; The top cover has a through hole I and a through hole II; a sleeve I is provided inside the through hole II; the sleeve I is a hollow structure with openings at both ends, and each end of the sleeve I is fixedly connected to one end of the through hole II, thereby forming a jacket structure I; The sand cup has two inner cavities, referred to as sand cup cavity I and sand cup cavity II respectively; a sleeve II is provided inside sand cup cavity II; the sleeve II is a hollow structure with open ends, and each end of the sleeve II is fixedly connected to one end of sand cup cavity II, thus forming a jacket structure II; The distribution plate is equipped with nylon melt channels and polyester melt channels; the inner wall of the nylon melt channel is equipped with a heat-insulating coating. Through hole I, sand cup inner cavity I, and polyester melt channel are connected sequentially from top to bottom to form the total polyester melt channel; The interior of sleeve I, the interior of sleeve II, and the nylon melt channel are connected sequentially from top to bottom to form the main nylon melt channel.

7. A method for improving the quality of fine denier split polyester-nylon composite yarn according to claim 6, characterized in that, The distribution board includes a first distribution board, a second distribution board, and a third distribution board connected from top to bottom.

8. A method for improving the quality of fine denier split polyester-nylon composite yarn according to claim 7, characterized in that, The heat insulation coating is made of Al2O3 ceramic.

9. A method for improving the quality of fine denier split polyester-nylon composite yarn according to claim 8, characterized in that, The polyester main housing is equipped with a polyester metering pump, and the output end of the polyester metering pump is connected to the upper opening of through hole I through a connecting pipe. The nylon auxiliary housing is equipped with a nylon metering pump. The output end of the nylon metering pump is connected to one end of a connecting pipe, and the other end of the connecting pipe passes through the nylon connection port and is connected to the upper end of the sleeve I.

10. A method for improving the quality of fine denier split polyester-nylon composite yarn according to claim 9, characterized in that, The shape inside sleeve I is exactly the same as the shape inside through hole I; the shape inside sleeve II is exactly the same as the shape inside the inner cavity I of the sand cup. The outer surface of sleeve I is equidistant from the inner wall of through hole II, and the outer surface of sleeve II is equidistant from the inner wall of sand cup cavity II.

11. A method for improving the quality of fine denier split polyester-nylon composite yarn according to claim 10, characterized in that, The spinneret assembly also includes ring I, ring II, ring III and ring IV; Rings I, II, III, and IV are all placed horizontally; The upper end of sleeve I is fixedly connected to the upper end of through hole II via ring I, and the lower end of sleeve I is fixedly connected to the lower end of through hole II via ring II. The upper end of sleeve II is fixedly connected to the upper end of the inner cavity II of the sand cup via ring III, and the lower end of sleeve II is fixedly connected to the lower end of the inner cavity II of the sand cup via ring IV.

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