Method for improving quality of fine denier splinter type polyester-nylon composite yarn

Abstract

The invention belongs to the technical field of spinning processing, and relates to a method for improving the quality of fine-denier split-type polyester-nylon composite filaments, and the fine-denier split-type polyester-nylon composite filaments comprise 10-30 wt% of nylon; the preparation process comprises the following steps: conveying a polyester melt and a chinlon melt into a spinning box body through respective pipelines, then respectively feeding the polyester melt and the chinlon melt into respective sand cups through respective channels, carrying out pressure filtration, then feeding the polyester melt and the chinlon melt into a distribution plate, converging and fusing the polyester melt and the chinlon melt according to a designed splinter shape after passing through the distribution plate, and extruding the polyester melt and the chinlon melt into filaments from spinneret orifices; finally, cooling, oiling, stretching, heat setting and winding forming are sequentially conducted on the filaments, and the fine denier splinter type polyester and nylon composite filaments are formed. The temperature difference between the chinlon melt and the polyester melt is controlled to be D when the chinlon melt enters a spinneret orifice, the splitting rate of the prepared product after splitting is larger than 99%, the dyeing M rate is larger than 99.5%, and the broken filament rate is smaller than 0.5%. By means of the method, the fine denier splinter type polyester-nylon composite yarn with the clear interface and the section free of deformation can be obtained.

Description

Technical Field

[0001] The present invention belongs to the technical field of spinning processing, and relates to a method for improving the quality of fine-denier split-type polyester-polyamide composite filaments. Background Art

[0002] The split-type polyester-polyamide composite filament is a circular cross-section fiber in which nylon is in a "starfish" shape and polyester is embedded between the star angles of the "starfish", and the polyester and nylon are fused together. After post-treatment fibrillation, the nylon and polyester are separated to form ultrafine fibers, and the finished fabric has the advantages of delicate wool feeling, soft hand feeling, strong hygroscopicity, good drapability, etc.

[0003] As Figure 1 shown, in the one-step production of split-type polyester-polyamide composite fibers, two polymer melts of polyester and nylon are respectively transported into the spinning box through the polyester melt pipeline and the nylon melt pipeline. The spinning box is composed of a main polyester box 2 and an auxiliary nylon box 1. Since the properties of the two polymer melts are different, the two boxes are respectively insulated by heat transfer media with different properties, and a heat insulation layer 3 is provided between the main and auxiliary boxes for heat insulation. The polyester metering pump 5 and the nylon metering pump 4 in their respective boxes accurately meter the two melts according to the process ratio, and then the polyester and nylon melts respectively enter the spinning assembly 8 insulated by the main polyester box through the connecting pipe 7 connected to the output end of the polyester metering pump and the connecting pipe 6 connected to the output end of the nylon metering pump. As Figure 3 、 Figure 5 shown, the polyester and nylon respectively enter their respective sand cups through the polyester melt main channel 10 and the nylon melt main channel 9 on the upper cover of the assembly, and after being filtered, pressurized by metal sand and a filter screen, they enter the distribution plate for splitting. The distribution plate is composed of the first, second, and third distribution plates from top to bottom. Along the upper edges of the first, second, and third distribution plates, the polyester and nylon melts are annularly arrayed and split into several thin streams in their respective channels, and finally converge and fuse at the lower edge of the third distribution plate according to the designed split shape, and are extruded into filaments from the spinneret holes. After cooling, oiling, stretching, and heat setting, they are wound into shape to form split-type polyester-polyamide composite fibers. After post-treatment fibrillation, the polyester and nylon are separated to finally form ultrafine fibers.

[0004] The main problems existing in the current production of fine-denier split-type polyester-polyamide composite filaments are as follows: Since the temperature difference between the melt boxes and the melt temperature difference of the two melts are both about 20 °C, the proportion of polyamide is small (generally 10-30 wt%), the flow rate is slow, and the polyamide melt and the polyester melt entering the component are adjacent to each other. Especially in the distribution plate, the channels of the two are narrow and arranged adjacent to each other in a circular array. There is always high-low temperature transfer between polyamide and polyester, and between polyamide and the main box body (even if there is a gap between the component and the box body, according to tests, the temperature difference between the outer wall of the component and the groove wall of the box body component is within 10 °C, and there is still a high temperature difference of more than 10 °C for polyamide). If the time is long enough, the heat transfer will be more sufficient. The viscosity of the polyamide melt will change in an over-temperature environment, and thermal degradation will occur after a long time, affecting the melt quality, and cross-sectional deformation will occur when it is fused with polyester, affecting the quality of the finished fiber.

[0005] In Document 1 (Discussion on the influencing factors of the dyeing of DTY finished filaments by POY spinning of cross-shaped split polyester-polyamide composite filaments [J]. Polyester Industry, 2018, 31(4):4.), the melting point of polyester with an intrinsic viscosity of 0.67 dl / g is 260 °C, the melting point of polyamide with a relative viscosity of 2.75 is 235 °C, the polyester box body temperature is 287-290 °C, and the polyamide box body temperature is 265-270 °C, all 25-35 °C higher than the melting point. Polyamide is easily degraded, and the melt uniformity becomes poor after degradation, affecting the cross-sectional stability and causing cross-sectional deformation.

[0006] In Document 2 (Discussion on the uses and production processes of polyester-polyamide composite filaments [J]. Synthetic Fibers, 2012(5):2.), the spinning temperature of the polyester-polyamide composite filaments must ensure that the melting temperature difference between the two chips is controlled within 15 °C to ensure good fiber cross-sectional images (because a large temperature difference makes it easy to form hairy filaments in the subsequent drawing and difficult to process). However, when the melting temperature difference is small, the two components are easily adhered and not easily peeled off.

[0007] Therefore, it is of great significance to study a method for improving the quality of fine-denier split-type polyester-polyamide composite filaments to solve the problems existing in the prior art. Summary of the Invention

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

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

[0010] A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments, where the proportion of polyamide in the fine-denier split-type polyester-polyamide composite filaments is 10-30 wt%; the preparation process flow of the fine-denier split-type polyester-polyamide composite filaments is as follows: the polyester melt and the polyamide melt are transported through their respective pipelines into the spinning box. The spinning box consists of a main polyester box and a sub polyamide box. The two boxes are independently temperature-controlled. The metering pumps in their respective boxes accurately measure the two melts according to the process ratio and then enter the same spinning component in the main polyester box. In the spinning component, the polyester melt and the polyamide melt enter their respective sand cups through their respective channels on the upper cover of the component, 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 holes. Finally, the filaments are successively cooled, oiled, stretched, heat-set, and wound into shape to obtain the fine-denier split-type polyester-polyamide composite filaments; control the temperature difference D between the polyamide melt and the polyester melt when entering the spinneret holes. After the fine-denier split-type polyester-polyamide composite filaments are opened, the polyester and the polyamide are separated to form ultrafine fibers. The opening rate > 99%, the dyeing M rate > 99.5%, and the hairiness rate < 0.5%.

[0011] ;

[0012] where Tm a is the melting point of polyester, Tm b is the melting point of polyamide, Tm a +A is the set temperature range of the box body of the polyester melt. A refers to the difference between the box body temperature of the polyester melt and the melting point of polyester. The value range of A is 25-30 °C, Tm b +B is the set temperature range of the box body of the polyamide melt. B refers to the difference between the box body temperature of the polyamide melt and the melting point of polyamide. The value range of B is 30-35 °C, and K is a coefficient obtained through a large number of experiments. The value range of K is 0.45-0.55.

[0013] In split-type polyester-nylon composite monofilaments, the nylon component primarily splits the polyester into six arc-shaped triangles. Nylon raw material is more expensive than polyester (typically twice as expensive), so the smaller the nylon content, the better. Currently, the percentage is typically 10-30% by weight. Due to the low nylon content in this type of product, especially for fine-denier yarns, the nylon melt's residence time within the component is significantly prolonged. This allows for more efficient heat transfer between the polyester and nylon, and between the component and the nylon within the main housing, compared to other types. This results in a smaller temperature difference between the polyester and nylon during fusion than with other types. Furthermore, this temperature difference has a greater impact on split-type products than on other types, significantly affecting cross-sectional deformation. At present, for other types of this type (split type) (such as split-type polyester-nylon composite yarn with nylon accounting for more than 30%, and coarse denier split-type polyester-nylon composite yarn), the nylon melt has a short residence time in the component (the melt capacity in the component is a constant value, and the residence time of the melt in the component = melt capacity / the amount of melt ejected from the component per unit time. The amount of fine denier yarn ejected per unit time is less than that of coarse denier yarn, and the residence time is longer; the proportion of nylon in the polyester-nylon composite yarn is small, and the amount of melt ejected from the component per unit time is even less, and the residence time is longer), and the high and low temperature heat transfer in the component is insufficient. According to the existing technology, simply adjusting the box temperature can control the temperature difference when the two melts merge within an acceptable range without affecting the cross-sectional deformation; or for other types (such as skin-core type and island-in-sea type), the influence of the temperature difference during fusion on the cross-sectional deformation is much lower than that of the split type, and simply adjusting the box temperature can also produce high-quality products.

[0014] During the production of fine-denier split-polyester / nylon composite yarn, when the two melts fuse, if the nylon temperature is too high, the nylon melt viscosity and surface tension decrease. This leads to excessive penetration of the polyester melt, which squeezes the shrinkage space of the nylon melt, causing adhesion between the polyester fibers (arc-shaped triangles), resulting in an unclear interface and a deformed cross-section. When the nylon is thermally degraded after prolonged overheating, the nylon melt becomes less uniform, seriously affecting the dispersion morphology of the melt. When fused with the polyester, this creates a more chaotic cross-sectional configuration and affects the longitudinal continuity of the yarn, resulting in poor spinnability and breakage. When the temperature drops too low, the nylon melt viscosity and surface tension increase, resulting in reduced adhesion when the polyester and nylon fuse, separation at the interface, poor fiber cohesion, and the generation of fuzz during stretching, which makes processing difficult.

[0015] The present invention controls the temperature difference D of polyester and nylon melts during fusion within a set value range, thereby ensuring that the polyester and nylon have a stable temperature difference, the melt viscosity does not fluctuate, the melt surface tension is stable, and when the two melts are fused, the shrinkage space of the other melt will not be squeezed out due to excessive infiltration of one melt; the two melts maintain a certain adhesion, no interface separation occurs, a stable cross-sectional configuration can be formed, and the continuity of the filaments in the length direction is maintained.

[0016] As the preferred technical solution:

[0017] A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments as described above, the specification of the fine-denier split-type polyester-polyamide composite filaments is 22~55 dtex / 12~48 f, and the single-filament fineness < 2.3 dtex.

[0018] A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments as described above, the intrinsic viscosity of polyester is 0.6~0.68 dL / g, and the melting point is 255~265 °C; the relative viscosity of the nylon melt is 2.4~2.75, and the melting point is 220~235 °C.

[0019] A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments as described above, the value range of D is 5~25 °C.

[0020] A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments as described above, the main polyester box body and the auxiliary nylon box body are connected left and right through a heat insulation layer to form a composite spinning box with a cubic structure;

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

[0022] The auxiliary nylon box body is an L-shaped box body composed of the auxiliary nylon box body B on the left and the auxiliary nylon box body A on the right. Both the auxiliary nylon box body A and the auxiliary nylon box body B are cubic structures, and the upper surfaces of the auxiliary nylon box body B and the auxiliary nylon box body A are on the same horizontal plane;

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

[0024] A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments as described above, the lower surface of the main polyester box body is provided with a component groove, and a part of the bottom area of the component groove is the heat insulation layer of the lower surface of the auxiliary nylon box body B; the component groove is used to install the spinneret plate assembly;

[0025] The composite spinning box is provided with a nylon connection port. One end of the nylon connection port is located at the bottom inside the auxiliary nylon box body 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 auxiliary nylon box body;

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

[0027] The upper cover is provided with through hole I and through hole II; a sleeve I is arranged inside through hole II; the sleeve I is a hollow structure with openings at both ends, and the two ends of the sleeve I are respectively and independently fixedly connected to one end of through hole II, thereby forming a jacket structure I; as Figure 3 shown, the only difference between the prior art upper cover and the present invention is that it does not include the jacket structure I.

[0028] There are 2 sand cup inner cavities inside the sand cup, which are respectively denoted as sand cup inner cavity I and sand cup inner cavity II; a sleeve II is arranged inside sand cup inner cavity II; the sleeve II is a hollow structure with openings at both ends, and the two ends of the sleeve II are respectively and independently fixedly connected to one end of sand cup inner cavity II, thereby forming a jacket structure II; as Figure 5 shown, the only difference between the prior art sand cup and the present invention is that it does not include the jacket structure II.

[0029] 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 insulation coating;

[0030] Through hole I, sand cup inner cavity I and the polyester melt channel are connected in sequence from top to bottom, and form a total polyester melt channel, and the total polyester melt channel is used for the polyester melt to flow through;

[0031] The inside of the sleeve I, the inside of the sleeve II and the nylon melt channel are connected in sequence from top to bottom, and form a total nylon melt channel, and the total nylon melt channel is used for the nylon melt to flow through;

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

[0033] As described above, a method for improving the quality of fine-denier split-type polyester-polyamide composite filaments, the distribution plate includes a first distribution plate, a second distribution plate and a third distribution plate connected from top to bottom. The first distribution plate, the second distribution plate, the third distribution plate and the spinneret are made of stainless steel, and the heat transfer coefficient of the stainless steel is 14 - 19 W / (m·k), and the heat transfer coefficient of carbon steel is 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, there are many channel branches in the distribution plate, the channels are narrow and mainly distributed in an array, and heat is easily transferred. As Figure 7 shown is a schematic diagram of the positions of the prior art distribution plate and the spinneret. The difference between the present invention and the prior art is that by adding a heat insulation coating in the nylon channel of the distribution plate, the transfer of high temperature from the main body to the nylon melt is reduced.

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

[0035] Temperature difference test method:

[0036] When the polyester and nylon melts fill the entire component and are extruded in combination through the spinneret holes, close the polyester metering pump. The temperature sensor measures the temperature when the nylon melt just enters the spinneret hole. Then close the nylon metering pump, open the polyester metering pump, and the temperature sensor measures the temperature when the polyester melt just enters the spinneret hole. Then calculate the difference between the two.

[0037] For a method of improving the quality of fine-denier split-type polyester-nylon composite filaments as described above, the heat-insulating coating is Al2O3 ceramic, which can withstand high temperatures above 1200 °C, and its heat transfer coefficient is 8.7 W / (m·k), lower than that of stainless steel.

[0038] For a method of improving the quality of fine-denier split-type polyester-nylon composite filaments as described above, a polyester metering pump is provided on the main polyester body, and the output end of the polyester metering pump is connected to the upper orifice of the through-hole I through a connecting pipe;

[0039] A nylon metering pump is provided on the auxiliary nylon body, and 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] For a method of improving the quality of fine-denier split-type polyester-nylon composite filaments as described above, the shape inside the sleeve I is exactly the same as the shape inside the through-hole I; the shape inside the sleeve II is exactly the same as the shape inside the inner cavity I of the sand cup;

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

[0042] For a method of improving the quality of fine-denier split-type polyester-nylon composite filaments as described above, the spinneret assembly further includes Ring I, Ring II, Ring III, and Ring IV;

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

[0044] The upper end of the sleeve I is fixedly connected to the upper end of the through-hole II through Ring I, and the lower end of the sleeve I is fixedly connected to the lower end of the through-hole II through Ring II;

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

[0046] For a method of improving the quality of fine-denier split-type polyester-nylon composite filaments as described above, the spinneret assembly further includes a housing, a disc spring, and a locking ring;

[0047] The spinneret plate, distribution plate, sand cup and upper cover are placed in the housing from bottom to top. The housing cooperates with the disc spring and locking ring to fix the spinneret plate, distribution plate, sand cup and upper cover in the housing. The shape and structure of the housing, disc spring and locking ring, as well as the connection relationship among the three and the upper cover, etc., are all prior arts.

[0048] Principle of the invention:

[0049] For the split-type polyester-polyamide composite filament, the polyester and polyamide melts enter from different channels along the lower edge of the third distribution plate and fuse in the spinneret holes to form a special cross-sectional shape. Its single-filament cross-section contains two components, polyester and polyamide. The polyamide is in the shape of a "starfish", and the polyester is divided into 6 arc-shaped triangles by the polyamide and embedded between the star angles of the "starfish". The single filament composed of polyester and polyamide is in a circular structure as a whole. Compared with other forms, the post-processing of the split-type polyester-polyamide composite filament also requires a fibrillating step, that is, physical or chemical methods are used to split the polyester and polyamide in the single filament into finer multi-filament profiled fibers, so that the fabric presents extremely superior tactile and visual effects. In order to fibrillate smoothly in the subsequent process and have high dyeing uniformity of the fibers after fibrillation (that is, the 6 polyester arc-shaped triangles have uniform shapes), it is required that the two melts have a clearer interface when fusing, and one melt should not occupy the shrinkage space of the other melt due to too strong infiltration. The two melts also need a certain adhesive force. If the adhesive force is too low, they will separate from each other with a little tension during the production process (premature fibrillation), affecting the fiber strength and prone to hairiness. When the viscosity fluctuates during the fusion of the two melts and the surface tension of the melt changes, it will affect the single ratio of the two components in the cross-section and the continuity of the filament in the length direction. Especially for fine-denier filaments, the unstable cross-sectional deformation caused by this influence has a greater impact on the product quality.

[0050] Because nylon has a starfish-like structure and a large specific surface area, while polyester forms six arc-shaped triangles, with two sides of each triangle in contact with the nylon, this type of nylon-polyester contact surface is significantly increased compared to other types. This significantly increases the contact surface area between the nylon and polyester, significantly increasing the nylon melt's exposure to high-temperature heat transfer even before fusion. If the temperature difference is too small (the nylon temperature is too high), the nylon melt's viscosity and surface tension decrease, leading to excessive penetration of the polyester melt, which squeezes the shrinkage space of the nylon melt and causes adhesion between the polyester fibers (the arc-shaped triangles), resulting in unclear interfaces and deformed cross-sections. When the nylon is subjected to prolonged overheating and thermal degradation, the nylon melt's uniformity deteriorates, severely affecting its dispersion. Fusion with the polyester results in a more chaotic cross-sectional configuration, affecting the longitudinal continuity of the yarn, and deteriorating spinnability, leading to yarn breakage. However, if the temperature difference is too large (the nylon temperature is too low), the nylon melt viscosity and surface tension increase, resulting in a decrease in the bonding strength when the polyester and nylon are fused. This can also cause cross-sectional deformation, interface separation, poor fiber cohesion, and the generation of fuzz during subsequent drawing, making processing difficult. Therefore, compared to the production of other types of polyester-nylon composite yarns, the production of split-type polyester-nylon composite yarns requires controlling the temperature of the two melts at fusion within a specific range.

[0051] After a lot of experimental verification, the formula designed by the present invention By controlling the range of the temperature difference D between the nylon melt and the polyester melt when entering the spinneret, it can be ensured that the two melts are uniform and have stable surface tension when they are fused, and a polyester-nylon composite yarn with a clear interface and no cross-section deformation can be obtained.

[0052] Reference 3 (Study on Calculation Method of Surface Tension of Polymer Melts [J]. Chemical Engineering and Equipment, 2012(9):2.) mentioned that the surface tension of polymer melts during polymer blending will affect the dispersion morphology of polymers. Polymers are prone to oxidative degradation when melted at higher temperatures. Therefore, experimental testing of the surface tension of polymer melts 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 melt is not accurately tested during temperature fluctuations. Testing the temperature difference when the two melts merge is more accurate than testing the temperature difference when the spinneret hole and in the box. Moreover, by controlling the temperature difference when the two melts merge, it is easier to obtain fine-denier split-type polyester-nylon composite yarns with clear interfaces and no cross-section deformation. The reasons are as follows:

[0053] (1) The quality of the two melts at the time of fusion determines the cross-sectional shape of the fusion of the two components. The two melts undergo sufficient heat conduction when entering the spinneret, and are closer to the fusion position of the two melts. That is, the temperature difference between the two melts when entering 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 quality degradation caused by cross-sectional deformation.

[0054] (2) In the box, the two melts have their own independent heat insulation, and the setting of the temperature of each box can maintain the best quality of each melt. When the nylon component is subjected to the high temperature transfer of the main box in the component, if the temperature of the nylon box is reduced to lower the melt temperature of the nylon in advance, then: the temperature of the nylon box is supplied by the nylon heat medium furnace, and the heat medium continues to be supplied upward 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 the long-distance pipeline conveying after it comes out of the screw; the adjustment of the box temperature is limited. When the nylon melt enters the component, rapid heat conduction occurs, offsetting the adjustment of the box temperature before the two components are fused.

[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 of the heat transfer surface. The melt has sufficient heat conduction with the heating heat medium in the box and the conveying pipeline, and the change in the melt temperature is very small as the time t increases. However, due to the large temperature difference between the nylon melt and the main box in the component, the heat conduction is greatly affected by the conduction time t. When producing different varieties of fibers, the residence time of the melt in the component is different. For example, when producing 30 dtex and 90 dtex fibers with the same component, the residence time t of the melt in the component increases by two times. Assuming 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 filaments than when producing coarse denier filaments. When the temperature difference exceeds a certain range, the fusion cross-section of the two components deforms.

[0056] The present invention increases the distance d of the heat transfer surface and reduces the thermal conductivity K by adding a jacket structure and a heat insulation coating, reduces the amount of heat conduction from the main box in the component to the nylon melt, controls the temperature difference when the polyester and nylon melts are fused, reduces cross-section deformation, and improves the product quality.

[0057] Beneficial effects:

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

[0059] (2) A method for improving the quality of fine denier split-type polyester-polyamide composite filaments of the present invention is simple, reduces cross-section deformation, and improves the product quality. Description of the drawings

[0060] Figure 1 It is a schematic diagram of the flow direction of the melt in the box for the one-step production of fine denier split-type polyester-polyamide composite filaments;

[0061] Figure 2 Cross-sectional view of the split-type polyester-polyamide composite filament assembly of the present invention;

[0062] Figure 3 Schematic diagram of the upper cover of the assembly of the prior art;

[0063] Figure 4 Schematic diagram of the upper cover of the assembly of the present invention;

[0064] Figure 5 Schematic diagram of the sand cup of the assembly of the prior art;

[0065] Figure 6 Schematic diagram of the sand cup of the assembly of the present invention;

[0066] Figure 7 Schematic diagram of the positions of the distribution plate and the spinneret plate of the prior art;

[0067] Figure 8 Schematic diagram of the fiber cross-section of the split-type polyester-polyamide composite filament monofilament under normal conditions;

[0068] Figure 9 Schematic diagram of the fiber cross-section of the split-type polyester-polyamide composite filament monofilament after complete fiber splitting under normal conditions;

[0069] Figure 10 Schematic diagram of the fiber cross-section of the split-type polyester-polyamide composite filament monofilament in the case of abnormality in Comparative Example 1;

[0070] Figure 11 Schematic diagram of the fiber cross-section of the split-type polyester-polyamide composite filament monofilament after complete fiber splitting in the case of abnormality in Comparative Example 1;

[0071] Figure 12 When producing fine-denier split-type polyester-polyamide composite filaments using the assembly with d2 being 1 mm and d1 being 3 mm, the Q b -(Ta3 - Tb3) curve detected and generated by the computer;

[0072] Among them, 1 - secondary box body, 2 - main box body, 3 - heat 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 - assembly, 9 - total nylon melt channel, 10 - total polyester melt channel, 11 - sand cup, 12 - first distribution plate, 13 - second distribution plate, 14 - third distribution plate, 15 - spinneret plate, 16 - spinneret holes, 17 - jacket structure I, 18 - jacket structure II, 19 - polyester, 20 - nylon, 21 - temperature sensor I, 22 - temperature sensor II. Specific embodiments

[0073] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and not to limit the scope of the present invention. In addition, it should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of this application.

[0074] The test methods related to the performance indicators of the present invention are as follows:

[0075] (1) Fiber cross-section detection method: Use the RX50M microscope produced by Ningbo Sunny Optical Instrument Co., Ltd. and the supporting fiber cross-section detection system for detection.

[0076] (2) Fiber opening method for split-type polyester-polyamide composite filaments: Put the finished fiber into a 1.5 wt% NaOH aqueous solution, heat it to boiling and boil for 45 minutes, take it out, dry it, and then check the fiber cross-section.

[0077] (3) Fiber opening rate of split-type polyester-polyamide composite filaments = number of single filaments of polyester completely peeled off from the polyamide component / total number of polyester single filaments × 100%.

[0078] A device for preparing the quality of fine-denier split-type polyester-polyamide composite filaments, the spinning box body includes a main polyester box body and a secondary polyamide box body; the main polyester box body and the secondary polyamide box body are connected left and right through a heat insulation layer to form a composite spinning box body with a cubic structure;

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

[0080] The secondary polyamide box body is an L-shaped box body composed of the secondary polyamide box body B on the left and the secondary polyamide box body A on the right. Both the secondary polyamide box body A and the secondary polyamide box body B are cubic structures, and the upper surfaces of the secondary polyamide box body B and the secondary polyamide box body A are on the same horizontal plane;

[0081] The lower surface of the main polyester box body is provided with a component groove, and a part of the bottom of the component groove is the heat insulation layer of the lower surface of the secondary polyamide box body B; the component groove is used to install the spinneret plate component;

[0082] The composite spinning box body is provided with a polyamide connection port. One end of the polyamide connection port is located at the bottom inside the secondary polyamide box body B, and the other end of the polyamide connection port is located at the bottom of the component groove. The polyamide connection port is used to connect the inside of the component groove with the inside of the secondary polyamide box body;

[0083] The spinneret assembly includes 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, which are connected in sequence from top to bottom;

[0084] As Figure 4 shown, the upper cover is provided with a through hole I and a through hole II; a sleeve I is arranged inside the through hole II; the sleeve I is a hollow structure with both ends open, and both ends of the sleeve I are respectively and independently fixedly connected to one end of the through hole II, thereby forming a jacket structure I17;

[0085] As Figure 6 shown, there are 2 sand cup inner cavities inside the sand cup, which are respectively denoted as sand cup inner cavity I and sand cup inner cavity II; a sleeve II is arranged inside the sand cup inner cavity II; the sleeve II is a hollow structure with both ends open, and both ends of the sleeve II are respectively and independently fixedly connected to one end of the sand cup inner cavity II, thereby 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 insulation coating;

[0087] A temperature sensor I 21 is installed in the nylon melt channel above the first distribution plate, which is used to detect the temperature of the nylon melt when it just enters the first distribution plate after leaving the sand cup; starting from the first distribution plate, it is annularly divided, flowing and squeezing in respective fine channels without communicating with each other, and only starts to converge and flow into each spinneret single hole together at the lower edge of the third distribution plate. A temperature sensor II 22 is installed in the spinneret single hole, which is used to detect the temperature when the polyester and nylon melts just enter the spinneret hole 16 and fuse;

[0088] The through hole I, the sand cup inner cavity I, and the polyester melt channel are connected in sequence from top to bottom, and form a polyester melt total channel 10, and the polyester melt total channel 10 is used for the polyester melt to flow through;

[0089] The inside of the sleeve I, the inside of the sleeve II, and the nylon melt channel are connected in sequence from top to bottom, and form a nylon melt total channel 9, and the nylon melt total channel 9 is used for the nylon melt to flow through;

[0090] The ring I, the ring II, the ring III, and the ring IV are all horizontally placed;

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

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

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

[0094] In the present invention, the calculation formula of the temperature difference D between the nylon melt and the polyester melt when entering the spinneret holes is as follows:

[0095] ;

[0096] In the formula, Tm a is the melting point of polyester, Tm b is the melting point of nylon, Tm a +A is the set temperature range of the polyester melt in the tank, A refers to the difference between the temperature of the polyester melt in the tank and the melting point of polyester, and the value range of A is 25-30 °C, Tm b +B is the set temperature range of the nylon melt in the tank, B refers to the difference between the temperature of the nylon melt in the tank and the melting point of nylon, and the value range of B is 30-35 °C, K is a coefficient, and the value range of K is 0.45-0.55;

[0097] When the melting point of polyester is 255-265 °C and the melting point of nylon is 220-235 °C, the value range of D is 5-25 °C.

[0098] The specific control steps of the above temperature difference are as follows:

[0099] Step 1: The temperature of the nylon melt when it reaches the spinneret holes through the distribution plate is Tb3. By adding a heat insulation coating with a lower heat transfer coefficient to the nylon channel, the thickness of the heat insulation coating is d2, and 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 of the nylon melt when it just enters the distribution plate after leaving the sand cup. By selecting different thicknesses of the jacket structure II with a thickness of d1, Tb2 is reduced.

[0101] The temperature sensors detect Ta3 (Ta3: the temperature of the polyester melt when it enters the spinneret holes), Tb2, and Tb3. By continuously adjusting and data analysis, the values of d2 and d1 are determined, and finally it is ensured that the temperature difference Ta3-Tb3 when the two melts are fused is within the value range.

[0102] When producing polyester-nylon composite filaments with different specifications and different proportions, the discharge amount Q of the nylon b is different. Since ρV is a fixed quantity, Q b can be used to characterize the residence time t, and the computer calculates the data and generates Q b-(Ta3 - Tb3) curve, used to determine the range of the split-type polyester-polyamide composite filament Q that can be simultaneously produced by using this component when both d2 and d1 are fixed values b (nylon discharge amount).

[0103] The specific adjustment process is as follows:

[0104] When performing Step 1 and not performing Step 2 (i.e., not adding the jacket structure II to the nylon sand cup and only adjusting the heat-insulating coating thickness d2 of the distribution plate), if 5°C < Ta3 - Tb3 < 25°C can be achieved, then determine the d2 value and the adjustment is completed.

[0105] When only performing Step 1 and the coating thickness has reached the maximum process requirement thickness (1 mm) but still does not satisfy 5°C < Ta3 - Tb3 < 25°C, then use the maximum coating thickness in Step 1 and also perform Step 2, that is, replace the nylon sand cup with the one having the jacket structure II. After Steps 1 and 2, analyze the Ta3, Tb2, and Tb3 data detected by the computer, select the appropriate thickness d1 of the jacket structure II to make 5°C < Ta,3 - Tb3 < 25°C, then determine the d1 and d2 values and the adjustment is completed.

[0106] After the d1 and d2 values of this component are determined, by adjusting the Q b value, detect Ta3, Tb2, and Tb3 correspondingly, and the computer calculates and generates the Q b -(Ta3 - Tb3) curve to make 5°C < Ta3 - Tb3 < 25°C, and obtain the value range of Q b from the curve, that is: the split-type polyester-polyamide composite filament Q within this range can be simultaneously produced by using the component with fixed values of d1 and d2 b of this range.

[0107] Example 1

[0108] A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments, using the above-mentioned preparation device, the specific process is as follows:

[0109] The preparation process flow of the fine-denier split-type polyester-polyamide composite filament is as follows: The polyester melt and the polyamide melt are transported through their respective pipelines into the main polyester housing and the auxiliary polyamide housing. The intrinsic viscosity of the polyester is 0.68 dL / g, and the melting point is 265 °C; the relative viscosity of the polyamide melt is 2.75, and the melting point is 235 °C; the two housings are independently temperature-controlled. After the metering pumps located in their respective housings meter the two melts, they enter the same spinning pack located in the main polyester housing. In the spinning pack, the polyester melt and the polyamide melt respectively enter their respective sand cups through the respective channels on the upper cover of the pack, are pressurized and filtered, then enter the distribution plate, converge and fuse according to the designed split shape after passing through the distribution plate, and are extruded into filaments from the spinneret holes. The temperature difference D between the polyamide melt and the polyester melt when entering the spinneret holes is controlled to be 11 °C (since 55 dtex / 48f is not very fine among fine-denier filaments and does not require too high a housing temperature to increase the fluidity of the melt, so A is taken as 25 °C and B is taken as 30 °C; since the number of single filaments is large and the distance between the polyester melt channel and the polyamide melt channel in the distribution plate is close, and there is more heat transfer, it is easier to achieve with a smaller K value, so K is taken as 0.45); finally, the filaments are successively cooled, oiled, drawn, heat-set and wound into shape to obtain the fine-denier split-type polyester-polyamide composite filament;

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

[0111] As Figures 8 - 9 shown, the specification of the finally obtained fine-denier split-type polyester-polyamide composite filament is 55 dtex / 48f, and the single-filament fineness is 1.15 dtex; the proportion of polyamide in the fine-denier split-type polyester-polyamide composite filament is 30 wt%, and the polyester 19 is in the shape of 6 arc triangles, and each arc triangle has two surfaces in contact with the polyamide 20; the polyamide discharge amount is 5.94 g / min; the fibrillation rate of the fine-denier split-type polyester-polyamide composite filament after fibrillation is 99.3%, the dyeing M rate is 99.8%, and the hairiness rate is 0.35%.

[0112] Comparative Example 1

[0113] A method for improving the quality of polyester-polyamide composite filaments is basically the same as that in Example 1, except that the components of the prior art as Figure 3 、 Figure 5 shown are used.

[0114] During the production process, the polyester metering pump was opened, and the nylon metering pump was closed. The temperature of the polyester melt when it just entered the spinneret holes was measured to be 275 °C; the polyester metering pump was closed, and the nylon metering pump was opened. The temperature of the nylon melt when it just entered the spinneret holes was measured to be 268 °C. The temperature difference between the polyester and nylon melts when they entered the spinneret holes was 7 °C.

[0115] The specifications of the finally produced split-type polyester-nylon composite filaments were 55 dtex / 48 f. The fibrillation rate of the fibers after fibrillation was 94.3%, the dyeing M rate was 91.3%, and the hairiness rate was 0.55%.

[0116] By comparing Comparative Example 1 with Example 1, it can be found that the fibrillation rate in Example 1 increased by 5.0%, the dyeing M rate increased by 8.5%, and the hairiness rate increased by 0.2%. This is because when producing split-type polyester-nylon composite filaments with a specification of 55 dtex / 48 f, the fibers are relatively fine, the nylon melt flow rate is relatively low, and the residence time in the assembly is relatively long, resulting in a decrease in the viscosity of the nylon melt and a decrease in the surface tension of the melt. The strong infiltration of the polyester melt squeezes the shrinkage space of the nylon melt, causing adhesion between the polyesters (arc triangles), making it difficult to fibrillate the finished fibers and affecting the dyeing uniformity.

[0117] As Figure 10 shown, when producing fine-denier split-type polyester-nylon composite filaments using the components of the prior art, due to the relatively low nylon melt flow rate and the too long residence time in the total channels of the assembly, and sufficient heat transfer from the high temperature of the polyester main body and the high temperature of the polyester melt, the temperature difference becomes smaller when the two melts reach the lower edge of the third spinneret plate and fuse. The temperature of the nylon melt increases, resulting in a decrease in the viscosity of the nylon melt and a decrease in the surface tension of the melt. The strong infiltration of the polyester melt squeezes the shrinkage space of the nylon melt, causing adhesion between some polyesters (arc triangles) and forming a deformed cross-section with a disordered polyester and nylon composition.

[0118] As Figure 11 shown, when producing fine-denier split-type polyester-nylon composite filaments using the components of the prior art, after the cross-section is deformed, during the subsequent fibrillation, the adhered polyesters cannot be fibrillated into uniform arc triangles, affecting the dyeing uniformity.

[0119] Example 2

[0120] A method for improving the quality of fine-denier split-type polyester-nylon composite filaments, using the above-mentioned preparation device, and the specific process is as follows:

[0121] The preparation process flow of the fine-denier split-type polyester-polyamide composite filament is as follows: The polyester melt and the polyamide melt are transported into the main polyester box body and the auxiliary polyamide box body through their respective pipelines. The intrinsic viscosity of polyester is 0.68 dL / g, and the melting point is 265 °C; the relative viscosity of the polyamide melt is 2.75, and the melting point is 235 °C; the two box bodies are independently temperature-controlled. After the metering pumps in their respective box bodies meter the two melts, they enter the same spinning pack in the main polyester box body. In the spinning pack, the polyester melt and the polyamide melt respectively enter their respective sand cups through their respective channels on the upper cover of the pack, are pressurized and filtered, then enter the distribution plate, converge and fuse according to the designed split shape after passing through the distribution plate, and are extruded into filaments from the spinneret holes. Control the temperature difference D between the polyamide melt and the polyester melt when entering the spinneret holes to be 12.5 °C (since 55 dtex / 24f is not very fine among fine-denier filaments and does not require too high a box body temperature to increase the flow state of the melt, so A is taken as 25 °C and B is taken as 30 °C; the number of monofilaments is moderate, the distance between the polyester melt channel and the polyamide melt channel in the distribution plate is moderate, and the heat transfer is moderate, K is taken as 0.5); finally, the filaments are successively cooled, oiled, drawn, heat-set and wound into shape to obtain the fine-denier split-type polyester-polyamide composite filament;

[0122] The spinning process parameters are as follows: the cooling temperature is 19 °C, the oiling rate is 1.08%, the draw ratio is 3.29 times, the heat-setting temperature is 130 °C, the temperature of the main polyester box body is 290 °C, the temperature of the auxiliary polyamide box body is 265 °C, the monomer suction pressure is 0.5 bar, the side blowing wind speed is 0.4 m / min, and the winding speed is 3500 m / min;

[0123] As Figure 12 shown, when the temperature of the main polyester box body is 290 °C, the temperature of the auxiliary polyamide box body is 265 °C, the thickness d2 of the heat-insulating coating reaches the maximum value of 1 mm, and the thickness d1 of the jacket structure II of the polyamide sand cup is taken as 3 mm, adjust the polyamide discharge volume Q b value, detect the Ta3 and Tb3 values, generate the Q b -(Ta3 - Tb3) curve. When the curve is within the rectangular frame, 11 °C < Ta3 - Tb3 < 14 °C (K is taken as 0.45 - 0.55), and the corresponding Q b value is 1.7 - 2.3 g / min, indicating that a component with d2 of 1 mm and d1 of 3 mm can be used to produce split-type polyester-polyamide composite filaments with a polyamide discharge volume of 1.7 - 2.3 g / min, meeting the requirement that the cross-section does not deform.

[0124] The specifications of the finally obtained fine-denier split-type polyester-polyamide composite filaments are 55 dtex / 24 f, and the fineness of the single filament is 2.29 dtex; the proportion of polyamide in the fine-denier split-type polyester-polyamide composite filaments is 10 wt%; the polyamide discharge is 1.93 g / min; after the fine-denier split-type polyester-polyamide composite filaments are opened, the opening rate is 99.1%, the dyeing M rate is 99.6%, and the hairiness rate is 0.43%.

[0125] Example 3

[0126] A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments, using the above-mentioned preparation device, the specific process is as follows:

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

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

[0129] The specifications of the finally obtained fine-denier split-type polyester-polyamide composite filaments are 22 dtex / 24 f, and the fineness of the single filament is 0.92 dtex; the proportion of polyamide in the fine-denier split-type polyester-polyamide composite filaments is 20 wt%; the polyamide discharge is 1.32 g / min; after the fine-denier split-type polyester-polyamide composite filaments are opened, the opening rate is 99.4%, the dyeing M rate is 99.7%, and the hairiness rate is 0.32%.

[0130] Example 4

[0131] A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments, using the above-mentioned preparation device, the specific process is as follows:

[0132] The preparation process flow of the fine-denier split-type polyester-polyamide composite filaments is as follows: The polyester melt and the polyamide melt are transported into the polyester main box body and the polyamide auxiliary box body through their respective pipelines. The intrinsic viscosity of the polyester is 0.6 dL / g, and the melting point is 255 °C; the relative viscosity of the polyamide melt is 2.4, and the melting point is 220 °C; the two box bodies are independently temperature-controlled. After the metering pumps in their respective box bodies meter the two melts, they enter the same spinning component in the polyester main box body. In the spinning component, the polyester melt and the polyamide melt respectively enter their respective sand cups through the respective channels on the upper cover of the component, 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 holes. Control the temperature difference D between the polyamide melt and the polyester melt when entering the spinneret holes to be 14.5 °C (since 33 dtex / 36f is of moderate thickness in fine-denier filaments, the box body temperature is appropriately selected, so A is taken as 27 °C and B is taken as 33 °C; the number of monofilaments is moderate, the distance between the polyester melt channel and the polyamide melt channel in the distribution plate is moderate, and the heat transfer is moderate, so K is taken as 0.5); finally, the filaments are successively cooled, oiled, drawn, heat-set and wound into shape to obtain the fine-denier split-type polyester-polyamide composite filaments;

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

[0134] The final specifications of the obtained fine-denier split-type polyester-polyamide composite filaments are 33 dtex / 36f, and the fineness of the monofilament is 0.92 dtex; the proportion of polyamide in the fine-denier split-type polyester-polyamide composite filaments is 20 wt%; the polyamide output is 2.11 g / min; the fibrillation rate of the fine-denier split-type polyester-polyamide composite filaments after fibrillation is 99.3%, the dyeing M rate is 99.7%, and the hairiness rate is 0.25%.

[0135] Example 5

[0136] A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments, using the above-mentioned preparation device, the specific process is as follows:

[0137] The preparation process flow of the fine-denier split-type polyester-polyamide composite filament is as follows: The polyester melt and the polyamide melt are transported through their respective pipelines into the main polyester box body and the auxiliary polyamide box body. The intrinsic viscosity of the polyester is 0.6 dL / g, and the melting point is 255 °C; the relative viscosity of the polyamide melt is 2.4, and the melting point is 220 °C; the two box bodies are independently temperature-controlled. After the metering pumps located in their respective box bodies meter the two melts, they enter the same spinning pack located in the main polyester box body. In the spinning pack, the polyester melt and the polyamide melt respectively enter their respective sand cups through the respective channels on the upper cover of the pack, are pressurized and filtered, then enter the distribution plate, converge and fuse according to the designed split shape after passing through the distribution plate, and are extruded into filaments from the spinneret holes. Control the temperature difference D between the polyamide melt and the polyester melt when entering the spinneret holes to be 16.5 °C (since 22 dtex / 12f is very fine in fine-denier filaments and a higher box body temperature is required to increase the fluidity of the melt, so A is taken as 30 °C and B is taken as 35 °C; due to the small number of monofilaments, the distance between the polyester melt channel and the polyamide melt channel in the distribution plate is far, and the heat transfer is less, so even if K takes a large value, it is easy to achieve, and K is taken as 0.55); finally, the filaments are successively cooled, oiled, drawn, heat-set and wound into shape to obtain the fine-denier split-type polyester-polyamide composite filament;

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

[0139] The specification of the finally obtained fine-denier split-type polyester-polyamide composite filament is 22 dtex / 12f, and the fineness of the monofilament is 1.83 dtex; the proportion of polyamide in the fine-denier split-type polyester-polyamide composite filament is 30 wt%; the polyamide output is 1.85 g / min; the fibrillation rate of the fine-denier split-type polyester-polyamide composite filament after fibrillation is 99.6%, the dyeing M rate is 99.8%, and the hairiness rate is 0.21%.

[0140] The following Table 1 shows the comparison of the residence time of the polyamide melt in the component for different specifications of polyester-polyamide composite filaments (the finer the fiber, the more suitable for low vehicle speed) when the polyester-polyamide ratio is 70:30 during the actual production process:

[0141] Table 1

[0142]

[0143] As can be seen from the comparison in Table 1 above, when producing polyester-polyamide composite filaments of different specifications, there is a huge difference in the residence time of the polyamide melt in the spinneret pack. At 22 dtex, it stays in the spinneret pack for 1160 seconds, while when producing 198 dtex, it only stays in the spinneret pack for 75 seconds. When producing thick denier filaments, the melt flow rate is fast and the two melts do not have enough time for sufficient heat transfer, and both mainly retain the melt temperature at the time in the melt box, resulting in a large temperature difference during fusion; while when producing fine denier filaments, the two melts have enough time for heat transfer, and the temperature difference during fusion is small. After sufficient heat transfer time, the temperatures of polyester and polyamide during fusion are shown in Table 2 below. Among them, the polyester melt box temperature is 290 °C, and the polyamide melt box temperature is 265 °C.

[0144] Table 2

[0145]

[0146] The effects to be achieved by using the technical solution of the present invention for fine denier polyester-polyamide composite filaments are shown in Table 3 below.

[0147] Table 3

[0148]

Claims

1. A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments, where the proportion of polyamide in the fine-denier split-type polyester-polyamide composite filaments is 10-30 wt%; the preparation process flow of the fine-denier split-type polyester-polyamide composite filaments is as follows: the polyester melt and the polyamide melt are transported through their respective pipelines into the spinning box, the spinning box consists of a main polyester box and a secondary polyamide box, after the metering pumps in their respective boxes meter the two melts, they enter the same spinning component in the main polyester box. In the spinning component, the polyester melt and the polyamide melt respectively enter their respective sand cups through their respective channels on the upper cover of the component, are pressurized and filtered, then enter the distribution plate, converge and fuse according to the designed split shape after passing through the distribution plate, and are extruded into filaments from the spinneret holes. Finally, the filaments are successively cooled, oiled, drawn, heat-set and wound into shape to obtain the fine-denier split-type polyester-polyamide composite filaments; the characteristics are as follows: The temperature difference D between the nylon melt and the polyester melt when entering the spinneret holes is controlled. The fine-denier split-type polyester-nylon composite filaments prepared have an opening rate > 99% after fibrillating, a dyeing M rate > 99.5%, and a hairiness rate < 0.5%. ； Where, Tm a is the melting point of polyester, Tm b is the melting point of polyamide, Tm a +A is the set temperature range of the box body for the polyester melt, the value range of A is 25~30°C, Tm b +B is the set temperature range of the box body for the polyamide melt, the value range of B is 30~35°C, K is a coefficient, and the value range of K is 0.45~0.

55.

2. A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments according to claim 1, characterized in that The fine-denier split-type polyester-nylon composite filaments have a specification of 22 - 55 dtex / 12 - 48 f, and the single-filament fineness < 2.3 dtex.

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

4. A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments according to claim 3, characterized in that, The value range of D is 5 - 25 °C.

5. A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments according to claim 1, characterized in that The main polyester box body and the auxiliary nylon box body are connected left and right through a heat-insulating layer to form a composite spinning box with a cubic structure. The main polyester box body is an L-shaped box body composed of the main polyester box body A on the left and the main polyester box body B on the right. Both the main polyester box body A and the main polyester box body B are cubic structures, and the lower surfaces of the main polyester box body A and the main polyester box body B are on the same horizontal plane. The auxiliary nylon box body is an L-shaped box body composed of the auxiliary nylon box body B on the left and the auxiliary nylon box body A on the right. Both the auxiliary nylon box body A and the auxiliary nylon box body B are cubic structures, and the upper surfaces of the auxiliary nylon box body B and the auxiliary nylon box body A are on the same horizontal plane.

6. A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments according to claim 5, characterized in that, The lower surface of the main polyester box body is provided with a component groove, and a partial area at the bottom of the component groove is the heat-insulating layer of the lower surface of the auxiliary nylon box body B; the component groove is used for installing the spinneret plate component. The composite spinning box is provided with a nylon connection port. One end of the nylon connection port is located at the bottom inside the auxiliary nylon box body B, and the other end of the nylon connection port is located at the bottom of the component groove. The spinneret plate component includes an upper cover, a sand cup, a distribution plate, and a spinneret plate connected in sequence from top to bottom. The upper cover is provided with through hole I and through hole II; a sleeve I is arranged inside through hole II; the sleeve I is a hollow structure with both ends open, and both ends of the sleeve I are respectively and separately fixedly connected to one end of through hole II, thus forming a jacket structure I. There are 2 sand cup inner cavities inside the sand cup, denoted as sand cup inner cavity I and sand cup inner cavity II respectively; a sleeve II is arranged inside the sand cup inner cavity II; the sleeve II is a hollow structure with both ends open, and both ends of the sleeve II are respectively and separately fixedly connected to one end of the sand cup inner cavity II, thus forming a jacket structure II. 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. Through hole I, sand cup inner cavity I, and the polyester melt channel are connected in sequence from top to bottom and form a total polyester melt channel. The inside of sleeve I, the inside of sleeve II, and the nylon melt channel are connected in sequence from top to bottom and form a total nylon melt channel.

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

8. A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments according to claim 7, characterized in that The heat-insulating coating is Al2O3 ceramic.

9. A method for improving the quality of fine-denier split-type polyester-polyamide composite filaments according to claim 8, characterized in that, A polyester metering pump is provided on the main polyester box body, and the output end of the polyester metering pump is connected to the upper orifice of through hole I through a connecting pipe. A nylon metering pump is provided on the auxiliary nylon box body, the output end of the nylon metering pump is connected to one end of a connecting pipe, and the other end of this connecting pipe passes through the nylon connection port and is connected to the upper end of sleeve I.

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

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

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