Method for producing polyester chips and preparing industrial polyester filaments by using ethylene glycol prepared from industrial tail gas and prepared industrial polyester filaments

Abstract

The invention discloses a method for producing polyester chips and preparing industrial polyester filaments by using ethylene glycol prepared from industrial tail gas and the prepared industrial polyester filaments. Industrial tail gas ethylene glycol with the ethylene glycol content larger than or equal to 99.9% is selected as a raw material, slurry with the molar ratio of EG to PTA being 1.0-1.3 is prepared, coal-based PET slices with the intrinsic viscosity being 0.6-0.8 dl / g and the terminal carboxyl group content being 25-30 mol / t are synthesized through an antimony-containing catalyst and 1-5 ppm of an acetic acid inhibitor, 1.0-1.2 dl / g coal-based high-viscosity slices are obtained after tackifying, and spinning is conducted on an industrial yarn production line; the temperature of the screw rod is controlled, and the lengths of a feeding section and a metering section are adjusted, so that the slices are fully fused, meanwhile, it is ensured that the melt does not further generate the chain breakage phenomenon along with thermal degradation due to the fact that the melt contains a small number of flexible chains, and the stability of the outlet pressure of the screw rod is ensured; the spinning assembly is of a multi-layer filter screen structure, so that the adverse effect caused by many impurities in the coal-based slice is improved; and the stretching and setting conditions are optimized and adjusted, so that the physical property, broken filaments and spinnability all meet the requirements.

Description

Technical Field

[0001] The present application belongs to the field of chemical fibers, and specifically relates to a method for producing polyester chips and polyester industrial filaments by using industrial tail gas to produce ethylene glycol, and the obtained polyester industrial filaments. Background Art

[0002] About 94% of ethylene glycol in the market is used as polyester raw material. The traditional production of ethylene glycol uses the petroleum ethylene route as the production process. Due to the scarcity of petroleum resources, the production process is greatly restricted in terms of resource utilization and production costs. However, my country has abundant coal resources, so the process of synthesizing ethylene glycol based on coal-based syngas has a wide range of raw materials, low prices, and high technical and economic efficiency.

[0003] The excessive reliance of chemical fiber production on petroleum-based chemicals has led to the massive consumption of non-renewable resources such as petroleum, causing resource depletion and environmental pollution.

[0004] Compared with petroleum-based ethylene glycol, using industrial tail gas as the raw material for producing ethylene glycol not only realizes the resource utilization of tail gas, but is also environmentally friendly and low-cost, and has strong market competitiveness. However, in the prior art, ethylene glycol produced with industrial tail gas as the raw material cannot be completely removed from the top of the process tower when entering the polyester production process because the reaction byproduct oxalic acid remains in the ethylene glycol. As a result, when entering the subsequent polycondensation process, the degree of polymerization increases while thermal degradation occurs, which is directly reflected in the final analytical index of the polyester, that is, the increase in the terminal carboxyl content. The terminal carboxyl content of polyester products can reflect the regularity of the polymer material chain, which is generally controlled below 30 mol / t. If the terminal carboxyl content rises to above 35 mol / t, it will cause changes in the processing performance of the polyester product after spinning, which is mostly manifested as an increase in the number of spinning breakages, and the strength index of the fiber product will also decline to varying degrees. In addition, a small amount of oxalic acid reacts with ethylene glycol to form an esterification reaction, and a small amount of flexible chains may be generated during the polycondensation reaction and enter the polyester product. As thermal degradation occurs, chain breaking may further occur, which is manifested as sudden fiber breakage during spinning, but the spinneret surface is very clean.

[0005] In the process of preparing polyester industrial filaments from petroleum-based chips, a three-layer filtration structure is used in the spinning assembly, with a felt mesh in the middle and supported by sieve plates at the top and bottom. In the process of preparing polyester industrial filaments from coal-based chips, there are relatively many impurities, and the melt has a greater impact on the filter mesh, resulting in clogging of the filtration structure and rapid pressure increase of the spinning assembly; the orifice expansion phenomenon is prone to occur during the spinning process, resulting in more spinning sticking to the spinning plate, hairy yarns, and injection head yarns.

[0006] Therefore, this application needs to solve the following technical problems:

[0007] 1) How to use industrial tail gas ethylene glycol as raw material for polyester process to obtain polyester chips;

[0008] 2) How to carry out solid phase viscosity enhancement process to improve the intrinsic viscosity of polyester chips;

[0009] 3) How to ensure that the physical properties, hairiness and other indicators of the produced polyester industrial filament meet the standards. Summary of the invention

[0010] In view of the above-mentioned shortcomings or deficiencies of the prior art, the technical problem to be solved by the present application is to provide a method for producing polyester chips and polyester industrial filaments by using industrial tail gas to produce ethylene glycol, and the prepared polyester industrial filaments.

[0011] To solve the above technical problems, this application is implemented through the following technical solutions:

[0012] The present application proposes a method for producing polyester chips and polyester industrial filaments by using industrial tail gas to produce ethylene glycol, comprising the following steps:

[0013] Step 1, adding p-phthalic acid (PTA), ethylene glycol (EG) obtained from industrial tail gas, catalyst preparation liquid, and 1-5 ppm acetic acid inhibitor into a slurry preparation system, and preparing a slurry with a molar ratio of EG:PTA of 1.0-1.3 under stirring; conveying the slurry to an esterification reactor to obtain an esterification primary product; conveying the esterification primary product to a pre-polycondensation reactor for pre-polycondensation reaction to obtain a polyester prepolymer; performing a final polycondensation reaction on the polyester prepolymer to obtain a polyester melt; cooling and granulating the polyester melt to obtain 0.6-0.8 dL / g PET polyester chips;

[0014] Step 2, placing the prepared 0.6-0.8 dl / g PET polyester chips in a reactor of a batch polymerization reactor to obtain 1.00-1.2 dL / g PET polyester chips;

[0015] Step 3, conveying 1.00-1.2 dL / g of PET polyester chips to a screw extruder, and extruding the melt through the screw extruder;

[0016] Step 4: The melt extruded by the screw extruder is distributed to the spinning manifold to form a spinning melt. The spinning melt is filtered and ejected from the spinneret at 295-305° C. to obtain a melt flow.

[0017] Step 5, subjecting the melt flow to a slow cooling treatment, and then cooling the melt flow by means of annular blowing or side blowing to obtain a wire strip body;

[0018] Step 6: After the cooling, the filament body enters the spinning tunnel for stretching, shaping and winding to obtain polyester industrial filaments prepared from coal-based polyester chips.

[0019] Furthermore, in the above method, the catalyst formulation liquid is a catalyst having an antimony content of 150 to 180 ppm;

[0020] And / or, the pressure of the esterification reaction kettle is set to 0.06-0.1Mpa, and the temperature is set to 253-273°C;

[0021] And / or, the vacuum degree of the pre-polycondensation reaction is 8-11 KPa, and the temperature is 260-280°C;

[0022] And / or, the vacuum degree of the final polycondensation reaction is 150-250 Pa, and the temperature is 272-293°C.

[0023] Furthermore, in the above method, the vacuum degree in the reactor of the intermittent polymerization reactor is stirred under the condition that the vacuum degree is less than or equal to 20 Pa, and the temperature in the reactor is uniformly raised to 90-120°C and heated for 2-10 hours by heating the heat transfer oil pipe, and then continued to be heated to 130-180°C and heated for 5-17 hours to obtain pre-crystallized sheets, and then continued to be uniformly heated to 200-240°C and continued to heat for 27-33 hours, so that the viscosity of the polyester chips is increased from 0.6-0.8dl / g to 1.00-1.2dL / g after solid-phase polymerization, and the moisture content is less than or equal to 15ppm.

[0024] Furthermore, in the above method, the screw outlet temperature of the screw extruder is ≥280°C; and / or the length ratio of the feed section, melting section and metering section of the screw extruder is 1:(1.0-3.0):(1.0-4.0); preferably, the length ratio of the feed section, melting section and metering section of the screw extruder is 1:(1.5-2.5):(2.5-4); more preferably, the length ratio of the feed section, melting section and metering section of the screw extruder is 1:(1.8-2.2):(2.8-4).

[0025] Furthermore, in the above method, the filtration uses a multi-layer metal filter screen, the filtration accuracy of the multi-layer metal filter screen decreases layer by layer along the traveling direction of the spinning melt, and the spinning melt is evenly distributed to the spinneret holes.

[0026] Furthermore, in the above method, the ratio of the micropore channel length of the spinneret hole to the diameter of the spinneret hole is 1.0 to 3.0; and / or the filtration accuracy is 20 to 30 μm.

[0027] Furthermore, in the above method, the slow cooling treatment is completed by a heating hood with a temperature of 300-330°C and an insulating cylinder with a height of 50-500mm; the ring blowing temperature is 50-70°C, the dynamic pressure is 0.02-0.06kPa, and the humidity is 50-70%; the side blowing temperature is 18-25°C, the wind speed is 0.4-0.6m / s, and the humidity is 50-70%.

[0028] Furthermore, in the above method, the parameters of the stretching and shaping include: a pulling speed of 300 to 4000 m / min; a total stretching multiple of 2.0 to 6.5; a shaping temperature of 230° C. to 260° C.; a total relaxation rate of 1.6 to 9%; and a winding speed of 2000 to 7000 m / min.

[0029] Furthermore, in the above method, the carboxyl end content of the polyester chips produced from industrial tail gas is 25 to 30 mol / t;

[0030] And / or, the color value L of the polyester chips produced from industrial tail gas is ≥79;

[0031] And / or, the color value b of the polyester chips produced from industrial tail gas is 1.5±2.0;

[0032] And / or, the moisture content of the polyester chips produced from industrial tail gas is ≤0.40%;

[0033] And / or, the content of diethylene glycol in the polyester chips produced from industrial tail gas is 0.80-1.00%.

[0034] Furthermore, in the above method, the polyester industrial filament has a fineness of 167 to 3300 dtex;

[0035] and / or, the breaking strength of the polyester industrial filament is ≥7.15 cN / dtex;

[0036] And / or, the coefficient of variation of the breaking strength of the polyester industrial filament is ≤4.0%;

[0037] And / or, the elongation at break of the polyester industrial filament is 11.5-24%;

[0038] And / or, the intermediate elongation of the polyester industrial filament is 5-10%.

[0039] The present application also proposes a polyester industrial filament prepared based on the above method.

[0040] Furthermore, the polyester industrial filament is used to prepare tire cord fabrics, safety belts, air bags or sewing threads.

[0041] Compared with the prior art, this application has the following technical effects:

[0042] The present application uses ethylene glycol prepared from industrial tail gas as raw material, formulates a slurry with a molar ratio of EG:PTA of 1.0 to 1.3, uses an antimony-containing catalyst and an acetic acid inhibitor, synthesizes coal-based PET chips with a characteristic viscosity of 0.6 to 0.8 dl / g and a terminal carboxyl content of 25 to 30 mol / t, and obtains 1.0 to 1.2 dl / g coal-based high-viscosity chips after viscosity increase, which are then spun on an industrial yarn production line; controls the screw temperature, and adjusts the length of the feed section and the metering section to fully melt the chips while ensuring that the melt does not further break due to the presence of a small amount of flexible chains as thermal degradation occurs, and ensures the stability of the screw outlet pressure; sets a filter element in the spinning assembly to improve the problem of rapid pressure increase in the spinning assembly due to the large number of impurities in the coal-based chips; optimizes and adjusts the stretching and shaping conditions to ensure that the physical properties, hair fibers, and spinnability meet the requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Other features, objects and advantages of the present application will become more apparent by reading the detailed description of non-limiting embodiments made with reference to the following drawings:

[0044] Figure 1 : Flow chart of the polyester process in one embodiment of the present application;

[0045] Figure 2 : A schematic diagram of the cross-sectional structure of a single hole of a spinneret in one embodiment of the present application;

[0046] Figure 3 : A schematic diagram of the partial structure of a spinning assembly in one embodiment of the present application;

[0047] In the figure: spinning assembly 1, spinning box 2, heating cover 3, spinneret 4, insulation cylinder 5; a is the melt flow direction; b is the melt flow direction; c is the cooling air direction. DETAILED DESCRIPTION

[0048] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0049] The present application uses ethylene glycol produced from industrial tail gas with an ethylene glycol content greater than or equal to 99.9% as a raw material, specifically, ethylene glycol is produced by the oxalic acid method using recycled steel plant tail gas, a slurry with a molar ratio of EG:PTA of 1.0 to 1.3 is prepared, ethylene glycol antimony with an antimony content of 150-180ppm is used as a catalyst, and 1 to 5ppm of acetic acid-based inhibitor is used, and a coal-based PET chip with a characteristic viscosity of 0.6 to 0.8dl / g and a terminal carboxyl content of 25 to 30mol / t is synthesized through a five-reactor process, and then a suitable viscosity-increasing process is used to increase the viscosity of the coal-based chip to 1.0 to 1.2dl / g, and the melting and cooling temperatures matching those of the industrial tail gas-based chip are designed to obtain a stable extruded spinning melt, and at the same time, the stretching process parameters are optimized to obtain polyester industrial filaments prepared from industrial tail gas-based polyester chips with qualified physical properties and hair.

[0050] A method for producing polyester chips and polyester industrial filaments by using industrial tail gas to produce ethylene glycol comprises the following steps:

[0051] Step 1, PTA, EG prepared from industrial tail gas, catalyst preparation liquid, and 1-5 ppm acetic acid inhibitor are added to the slurry preparation system, and a slurry with a molar ratio of EG:PTA of 1.0-1.3 is prepared under stirring; the prepared slurry is then sent to an esterification reactor through a slurry delivery pump, and stirred at a pressure of 0.06-0.1 MPa and a temperature of 253-273° C. to obtain an esterification initial product; the esterification initial product is then transported to a pre-polycondensation reactor with a vacuum degree of 8-11 KPa and a temperature of 260-280° C. through a pressure difference to perform a pre-polycondensation reaction to obtain a polyester prepolymer; the prepolymer is then transported to a vacuum degree of 150-250 Pa and a temperature of 272-293° C. through a prepolymer delivery pump to perform a final polycondensation reaction to obtain a polyester melt; finally, the polyester melt is cooled and granulated to obtain 0.6-0.8 dL / g PET polyester chips, such as Figure 1 shown.

[0052] When using ethylene glycol obtained from industrial tail gas to react with PTA to make polyester chips, the prepared slurry needs to be sent to the esterification reactor through a slurry delivery pump. The temperature of the first esterification reactor is controlled in the range of 258-262°C, and the temperature of the second esterification reactor is 262-276°C, which is about 3°C ​​higher than the normal use of petroleum-based ethylene glycol, and 2°C beyond the normal control range. The purpose is to promote the forward reaction. The increase in esterification temperature in the polyester process will lead to an increase in the reaction rate, so the esterification temperature is an important control parameter. The influence of temperature Under the condition of a certain EG / PTA molar ratio, the reaction rate will increase with the increase in reaction temperature, the esterification reaction will accelerate, and the time will be shortened, but it will also lead to the acceleration of side reactions in the system, the increase in diethylene glycol (DEG) content, and ultimately the increase in DEG content in the sliced ​​product, which means that in the polyester production process, the temperature needs to be carefully controlled to ensure product quality and output. Otherwise, the melting point of the product will be lower and the hue will be worse.

[0053] In order to obtain slices with the same indicators, the by-product DEG content increased accordingly by changing the process conditions such as temperature, liquid level, and catalyst. By selecting a suitable acetic acid-based inhibitor and controlling the added amount within the range of 1-5ppm, the DEG content was controlled within the normal range.

[0054] Specifically, the reactor used for the final polycondensation reaction is a squirrel cage horizontal reactor. The vacuum degree is adjusted by adjusting the amount of steam sucked into the ethylene glycol steam jet pump. The jacket of the reactor is heated by a gas phase heat medium, which is generated by a heat medium evaporator. The temperature of the entire polymerization section will be from 274°C to 293°C. Temperature is one of the important means to control the degree of polymerization. If the temperature fluctuates greatly during the entire process, it will affect the fluctuation of the degree of polymerization. In addition, too high a temperature will also cause the antioxidant capacity of the ester particles to decrease, resulting in an increase in the B value, affecting the quality of the final product. In order to simultaneously ensure the degree of polymerization and the B value of the product, a liquid level gauge is set on the inlet and outlet sides of the reactor. The feed amount of the prepolymer delivery pump is adjusted by the two liquid level values ​​to control the residence time of the material.

[0055] The antimony content in the catalyst formulation liquid is 150-180ppm; specifically, ethylene glycol antimony is used as a catalyst for the polycondensation reaction in the production process, and the catalyst is controlled between 150-180ppm when ethylene glycol is prepared from industrial tail gas to prepare slices, while the antimony content in the petroleum-based catalyst formulation liquid is 170-200ppm. The antimony content in the catalyst formulation liquid of the present application is reduced by an average of 20ppm. If the amount of catalyst added is large and other conditions are the same, the polycondensation reaction rate is fast and the viscosity is high; if the amount of catalyst added is small and other conditions are the same, the polycondensation reaction rate is reduced and the viscosity is low.

[0056] The intrinsic viscosity of the polyester chips prepared from industrial tail gas is 0.6-0.8 dl / g.

[0057] The terminal carboxyl content of the polyester chips prepared from industrial tail gas is 25-30 mol / t.

[0058] The color value L of the polyester chips made from industrial tail gas is ≥79.

[0059] The color value b of the polyester chips made from industrial tail gas is 1.5±2.0.

[0060] The moisture content of the polyester chips produced from industrial tail gas is ≤0.40%.

[0061] The content of diethylene glycol in the polyester chips prepared from industrial tail gas is 0.80-1.00%.

[0062] Step 2, placing the prepared 0.6-0.8dL / g PET polyester chips in a reactor of a batch polymerization reactor, stirring under a condition where the vacuum degree is less than or equal to 20pa, and uniformly raising the temperature in the reactor to 90-120°C and heating for 2-10h by heating the heat transfer oil pipe, and then continuing to heat to 130-180°C and heating for 5-17h to obtain pre-crystallized chips, and then continuing to heat the temperature in the reactor to 200-240°C by heating the heat transfer oil pipe, and continue heating for 27-33 hours, so that the viscosity of the polyester chips is increased from 0.6-0.8dl / g to 1.00-1.2dL / g after solid phase polymerization, and the moisture content of the final high-viscosity chips is less than or equal to 15ppm.

[0063] Step 3: conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw aspect ratio is 24-33, and the screw outlet temperature is ≥280°C.

[0064] Since oxalic acid is a byproduct of the reaction of industrial tail gas to ethylene glycol, and oxalic acid will remain in ethylene glycol, the boiling point of oxalic acid is 150°C, and it cannot be removed in the process tower. At the bottom of the process tower, it will be discharged together with the ethylene glycol product and enter the polymerization section production system. During the polymerization process, the phenomenon of increased flexible chains will appear, resulting in a decrease in the thermal stability of the polyester product. Therefore, the length of each functional zone of the screw used for spinning industrial tail gas coal-based chips should be different from that of petroleum-based chips. According to the bulk density and melting time of industrial tail gas coal-based chips after drying, by optimizing each functional section, such as increasing the length of the melting section and metering section, and reducing the length of the feed section, the stability of the screw extrusion volume and extrusion pressure can be guaranteed, thereby ensuring the normal spinning production.

[0065] Since oxalic acid, another byproduct of oxalic acid, cannot be completely removed from the process tower during the polyester production process, the composition of industrial tail gas coal-based chips is complex, and the melting rates of different components and particles of different shapes vary greatly. Therefore, compared with the spinning of petroleum-based chips, the melting process of industrial tail gas coal-based chips should adopt relatively mild melting conditions, that is, appropriately lengthen the melting section or metering section to extend the residence time, increase the viscosity to improve the mechanical properties of coal-based polyester filaments, and appropriately reduce the temperature of the melting section and metering section to reduce melt degradation. According to the above-mentioned differences in the characteristics of industrial tail gas coal-based chips and petroleum-based chips, the length of the metering section can also be appropriately increased to increase its residence time, effectively stabilize the screw extrusion pressure, and also play an important role in stabilizing spinning.

[0066] Step 4: The extruded melt is distributed to the melt pipes of each spinning box 2 through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly 1 through the metering pump and is filtered through the filter screen in the spinning assembly 1. The melt is ejected from the spinneret 4 to obtain a thin melt flow, such as Figure 3 The spinning manifold 2 includes the metering pump and the spinning assembly 1, and the spinning assembly 1 includes a filter screen and a spinneret 4. The number of spinneret holes in the spinneret 4 is 28-960; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0, as shown in FIG. Figure 2 As shown, L1 is the microporous channel length, D1 is the spinneret diameter; the filter screen in the spinning assembly 1 has a filter screen accuracy of 5 to 30 μm to improve the uniformity of the filament body. The spinning manifold 2 is heated using a biphenyl temperature of 295 to 305°C to maintain good melt fluidity and pressure.

[0067] Industrial tail gas-made thickening slices have many impurities and are easy to degrade. During the spinning process, the orifice expansion phenomenon is prone to occur, resulting in many spinning sticky plates, hairy fibers, and injection head fibers. According to the characteristics of industrial tail gas-made thickening slices, suitable component filters are designed, with a multi-layer metal filter structure to improve the problem of coal-based slices with many impurities leading to fast component pressure increase, reduce the shear rate of the melt passing through the spinneret hole, significantly suppress the expansion phenomenon, greatly reduce defects and injection head fibers, and greatly improve spinnability. At present, the maximum spinning speed can reach 5600m / min, which has reached the same level as petroleum-based melt spinning.

[0068] Step 5, after slow cooling treatment of each group of melt streams, cool the melt streams by ring blowing or side blowing to obtain the wire body. Among them, the temperature of the ring blowing is 50-70°C, the dynamic pressure is 0.02-0.06 kPa, and the humidity is 50-70%; the temperature of the side blowing is 18-25°C, the wind speed is 0.4-0.6 m / s, and the humidity is 50-70%. The slow cooling device includes a heating hood 3 and an insulating tube 5. The melt streams ejected from the spinneret 4 enter the heating hood 3 and the insulating tube 5 successively; the temperature control point of the heating hood 3 is 300-330°C to maintain a good thermal insulation effect. The function of the heating hood 3 is to heat the internal air so that the melt stays in the hot air for a period of time and does not cool down rapidly. On the one hand, it can make the melt less likely to break; on the other hand, it can eliminate the internal stress of macromolecules and improve the tensile properties of fibers. The heat-insulating cylinder 5 with a height of 50 to 500 mm is used, that is, the distance traveled by the melt stream in the heat-insulating cylinder 5 is 50 to 500 mm of the height of the heat-insulating cylinder 5, so as to improve the phenomenon of large CV value of physical properties and many broken fibers caused by uneven cooling. The melt stream coming out of the heat-insulating cylinder 5 enters the ring blowing or side blowing device. The heat-insulating cylinder 5 has the following functions: extending the length of the windless belt, on the one hand, reducing the impact of the airflow below on the spinneret 4 and the unsolidified melt; on the other hand, it also plays the role of delaying cooling, so that the spinning stretching is completed before the melt solidifies, which is conducive to the formation of macromolecular straight chains and the uniformity of orientation of each part; its length is variable, which has a great influence on the elongation at break of the fiber.

[0069] Step 6, the cooled filament body is passed through a spinning tunnel for stretching, shaping and winding to obtain polyester industrial filaments prepared from industrial tail gas coal-making based polyester chips, wherein the stretching and shaping parameters are: a pulling speed of 300 to 4000 m / min; oiling on the surface of the filament body; a total stretching multiple of 2.0 to 6.5; a shaping temperature of 230°C to 260°C; a total relaxation rate of 1.6 to 9%, and the winding is carried out at a winding speed of 2000 to 7000 m / min to obtain polyester industrial filaments prepared from industrial tail gas coal-making based polyester chips.

[0070] The polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips have a fineness of 100-3300 dtex.

[0071] The breaking strength of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is greater than or equal to 7.15 cN / dtex.

[0072] The coefficient of variation of breaking strength of the polyester industrial filament prepared from the industrial tail gas coal-based polyester chips is less than or equal to 4.0%.

[0073] The breaking elongation of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is 11.5-24%.

[0074] The intermediate elongation of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is 5-10%.

[0075] The present application uses industrial tail gas as raw material to produce ethylene glycol. Since the reaction by-product oxalic acid will remain in the product ethylene glycol, it cannot be completely removed from the top of the process tower when entering the polyester production process. A small amount of oxalic acid reacts with ethylene glycol for esterification, and a small amount of flexible chains may be generated during the polycondensation reaction and enter the polyester finished product. After viscosity enhancement, 1.0-1.2dl / g coal-based viscosity enhanced chips are obtained and spun on the existing industrial yarn production line; the screw temperature is controlled at 280-310°C to fully melt the chips while ensuring that the melt does not further break due to the presence of a small amount of flexible chains as thermal degradation occurs, and the screw outlet pressure is guaranteed to be stable; the spinning assembly 1 uses a multi-layer metal filter structure of 20-30μm to improve the problem of fast pressure increase of the spinning assembly 1 due to the large number of impurities in the coal-based chips; the stretching and shaping conditions are optimized and adjusted so that the physical properties, hair fibers and spinnability can meet the requirements. The production process parameters suitable for coal-based chips were summarized, which can stabilize coal-based polyester industrial filaments, and the various indicators of coal-based polyester industrial filaments are close to those of petroleum-based filaments of the same specifications.

[0076] The purity of ethylene glycol is close to the lower limit of the index, only 99.92%, which is significantly lower than the 99.99% of petroleum-based ethylene glycol; the water content is 3.4 times that of petroleum-based ethylene glycol, which increases the burden on the process tower and the vacuum, and affects the viscosity and color value of the slices. Taking this influence into account, the esterification temperature will be increased during the trial period, the liquid level in the polymerization section will be increased, and the retention time will be increased to compensate for possible fluctuations; the increase in ash content will also lead to an increase in impurities in the entire system, affecting the color value of the product and causing the L value to decrease. The ultraviolet transmittance of ethylene glycol products made from industrial tail gas is low, mainly because the coke produced during the distillation process of ethylene glycol enters the product. These impurities eventually affect the L value of the product in polyester synthesis. In view of the possible influence, the reaction temperature will be lowered in the polymerization section to compensate for the color value changes caused by high temperature.

[0077] Polyester industrial filaments prepared from coal-based polyester chips produced using industrial tail gas can be used to prepare tire cord fabrics, sewing threads, air bags or seat belts.

[0078] When used to prepare polyester industrial filament for tire cord fabric, the specific steps are:

[0079] Step 1: Add PTA, EG prepared from industrial tail gas, catalyst preparation liquid, and 1-5 ppm acetic acid inhibitor into the slurry preparation system, and prepare a slurry with a molar ratio of EG:PTA of 1.0-1.3 under stirring, wherein the antimony content in the catalyst preparation liquid is 150-180 ppm; then, the prepared slurry is sent into the esterification reactor through a slurry delivery pump, and stirred at a pressure of 0.06-0.1 MPa and a temperature of 253-273° C. The initial esterification product can be obtained; then the initial esterification product is transported to a pre-polycondensation reactor with a vacuum degree of 8-11 KPa and a temperature of 260-280° C. through a pressure difference to carry out a pre-polycondensation reaction to obtain a polyester prepolymer; then the prepolymer is transported to a reactor with a vacuum degree of 150-250 Pa and a temperature of 272-293° C. through a prepolymer transport pump to carry out a final polycondensation reaction to obtain a polyester melt; finally, the polyester melt is cooled and granulated to obtain 0.6-0.8 dL / g PET polyester chips.

[0080] Step 2, placing the prepared 0.6-0.8dL / g PET polyester chips in a reactor of a batch polymerization reactor, stirring under a condition where the vacuum degree is less than or equal to 20pa, and uniformly raising the temperature in the reactor to 90-120°C and heating for 2-10h by heating the heat transfer oil pipe, and then continuing to heat to 130-180°C and heating for 5-17h to obtain pre-crystallized chips, and then continuing to heat the temperature in the reactor to 200-240°C by heating the heat transfer oil pipe, and continue heating for 27-33 hours, so that the viscosity of the polyester chips is increased from 0.6-0.8dl / g to 1.00-1.2dL / g after solid phase polymerization, and the moisture content of the final high-viscosity chips is less than or equal to 15ppm.

[0081] Step 3, conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw aspect ratio is 24-33, the screw outlet temperature is ≥280°C, and the length ratio of the feed section, the melting section, and the metering section in the screw extruder is 1: (1.0-3.0): (1.0-4.0), the feed section temperature is 290-310°C, the melting section temperature is 300-310°C, and the metering section temperature is 280-295°C.

[0082] Step 4: The extruded melt is distributed to the melt pipes of each spinning manifold 2 through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly 1 through a metering pump and is filtered through the filter screen in the spinning assembly 1. The melt is ejected from the spinneret 4 to obtain a melt stream. The number of spinneret holes in the spinneret 4 is 192-960; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; the filter screen accuracy of the filter screen in the spinning assembly 1 is 5-30 μm to improve the uniformity of the filament body. A biphenyl temperature of 295-305°C is used to maintain good melt fluidity and pressure.

[0083] Step 5: After the melt stream is subjected to slow cooling treatment, the melt stream is cooled by annular blowing to obtain the filament body. The annular blowing temperature is 50-70°C, the dynamic pressure is 0.02-0.06 kPa, and the humidity is 50-70%. During the slow cooling treatment, a heating cover 3 with a temperature of 300-330°C and a heat insulation tube 5 with a height of 50-120 mm are used.

[0084] Step 6: After the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips. Specifically, oil is applied on the surface of the filament body, and then stretched, shaped and wound; wherein the stretching and shaping is completed by six pairs of rollers; the temperature of the first pair of rollers is 80-95°C, the speed is 2700-3200 m / min, the temperature of the second pair of rollers is 90-100°C, the speed is 3700-4300 m / min, and the second pair of rollers is 100-2000 m / min. m / min, the temperature of the third, fourth and fifth pairs of rollers is 240-260°C, the speed is 5600-6000 m / min, the sixth pair of rollers is not heated, and the speed is 5500-5900 m / min; the parameters of stretching and shaping are: total stretching multiple is 2.0-3.0; total relaxation rate is 2.0-5.0%, and winding is carried out at a winding speed of 5000-6000 m / min to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips.

[0085] The polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips have a fineness of 1100-3300 dtex.

[0086] The breaking strength of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is greater than or equal to 7.15 cN / dtex.

[0087] The coefficient of variation of the breaking strength of the polyester industrial filament prepared from the industrial tail gas coal-based polyester chips is less than or equal to 3.0%.

[0088] The breaking elongation of the polyester industrial filament prepared from the industrial tail gas coal-based polyester chips is 11.5-15.5%.

[0089] The intermediate elongation of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is 5-7%.

[0090] When used to prepare polyester industrial filament for sewing thread, the specific steps are:

[0091] Step 1: Add PTA, EG prepared from industrial tail gas, catalyst preparation liquid, and 1-5 ppm acetic acid inhibitor into the slurry preparation system, and prepare a slurry with a molar ratio of EG:PTA of 1.0-1.3 under stirring, wherein the antimony content in the catalyst preparation liquid is 150-180 ppm; then, the prepared slurry is sent into the esterification reactor through a slurry delivery pump, and stirred at a pressure of 0.06-0.1 MPa and a temperature of 253-273° C. The initial esterification product can be obtained; then the initial esterification product is transported to a pre-polycondensation reactor with a vacuum degree of 8-11 KPa and a temperature of 260-280° C. through a pressure difference to carry out a pre-polycondensation reaction to obtain a polyester prepolymer; then the prepolymer is transported to a reactor with a vacuum degree of 150-250 Pa and a temperature of 272-293° C. through a prepolymer transport pump to carry out a final polycondensation reaction to obtain a polyester melt; finally, the polyester melt is cooled and granulated to obtain 0.6-0.8 dL / g PET polyester chips.

[0092] Step 2, placing the prepared 0.6-0.8dL / g PET polyester chips in a reactor of a batch polymerization reactor, stirring under a condition where the vacuum degree is less than or equal to 20pa, and uniformly raising the temperature in the reactor to 90-120°C and heating for 2-10h by heating the heat transfer oil pipe, and then continuing to heat to 130-180°C and heating for 5-17h to obtain pre-crystallized chips, and then continuing to heat the temperature in the reactor to 200-240°C by heating the heat transfer oil pipe, and continue heating for 27-33 hours, so that the viscosity of the polyester chips is increased from 0.6-0.8dl / g to 1.00-1.2dL / g after solid phase polymerization, and the moisture content of the final high-viscosity chips is less than or equal to 15ppm.

[0093] Step 3, conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw aspect ratio is 24-33, the screw outlet temperature is ≥280°C, and the length ratio of the feed section, the melting section, and the metering section in the screw extruder is 1: (1.0-3.0): (1.0-4.0), the feed section temperature is 290-310°C, the melting section temperature is 300-310°C, and the metering section temperature is 280-295°C.

[0094] Step 4: The extruded melt is distributed to the melt pipes of each spinning manifold 2 through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly 1 through a metering pump and is filtered through the filter screen in the spinning assembly 1. The melt is ejected from the spinneret 4 to obtain a melt stream. The number of spinneret holes in the spinneret 4 is 28-144; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; the filter screen accuracy of the filter screen in the spinning assembly 1 is 5-30 μm to improve the uniformity of the filament body. A biphenyl temperature of 295-305°C is used to maintain good melt fluidity and pressure.

[0095] Step 5: After the melt stream is subjected to slow cooling treatment, the melt stream is cooled by side blowing to obtain the wire body. The side blowing temperature is 18-25°C, the wind speed is 0.4-0.6 m / s, and the humidity is 50-70%. During the slow cooling treatment, a heating cover 3 with a temperature of 300-330°C and a heat insulation cylinder 5 with a height of 100-300 mm are used.

[0096] Step 6: After the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips. Specifically, oil is applied on the surface of the filament body, and then stretched, shaped and wound; wherein the stretching and shaping is completed by five pairs of rollers; the temperature of the first pair of rollers is 80-95°C, the speed is 350-550 m / min, the temperature of the second pair of rollers is 100-125°C, the speed is 350-550 m / min, the temperature of the third pair of rollers is 1 The temperature of the fourth pair of rollers is 230-255°C, the speed is 2400-2700 m / min, the fifth pair of rollers is not heated, and the speed is 2300-2500 m / min; the parameters of stretching and shaping are: total stretching multiple is 5-6.2; total relaxation rate is 3-8%, and winding is carried out at a winding speed of 2000-4000 m / min to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips.

[0097] The polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips have a fineness of 100-1110 dtex.

[0098] The breaking strength of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is greater than or equal to 7.5 cN / dtex.

[0099] The coefficient of variation of breaking strength of the polyester industrial filament prepared from the industrial tail gas coal-based polyester chips is less than or equal to 4.0%.

[0100] The breaking elongation of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is 13-19%.

[0101] When used to prepare polyester industrial filament for airbags, the specific steps are:

[0102] Step 1: Add PTA, EG prepared from industrial tail gas, catalyst preparation liquid, and 1-5 ppm acetic acid inhibitor into the slurry preparation system, and prepare a slurry with a molar ratio of EG:PTA of 1.0-1.3 under stirring, wherein the antimony content in the catalyst preparation liquid is 150-180 ppm; then, the prepared slurry is sent into the esterification reactor through a slurry delivery pump, and stirred at a pressure of 0.06-0.1 MPa and a temperature of 253-273° C. The initial esterification product can be obtained; then the initial esterification product is transported to a pre-polycondensation reactor with a vacuum degree of 8-11 KPa and a temperature of 260-280° C. through a pressure difference to carry out a pre-polycondensation reaction to obtain a polyester prepolymer; then the prepolymer is transported to a reactor with a vacuum degree of 150-250 Pa and a temperature of 272-293° C. through a prepolymer transport pump to carry out a final polycondensation reaction to obtain a polyester melt; finally, the polyester melt is cooled and granulated to obtain 0.6-0.8 dL / g PET polyester chips.

[0103] Step 2, placing the prepared 0.6-0.8dL / g PET polyester chips in a reactor of a batch polymerization reactor, stirring under a condition where the vacuum degree is less than or equal to 20pa, and uniformly raising the temperature in the reactor to 90-120°C and heating for 2-10h by heating the heat transfer oil pipe, and then continuing to heat to 130-180°C and heating for 5-17h to obtain pre-crystallized chips, and then continuing to heat the temperature in the reactor to 200-240°C by heating the heat transfer oil pipe, and continue heating for 27-33 hours, so that the viscosity of the polyester chips is increased from 0.6-0.8dl / g to 1.00-1.2dL / g after solid phase polymerization, and the moisture content of the final high-viscosity chips is less than or equal to 15ppm.

[0104] Step 3, conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw aspect ratio is 24-33, the screw outlet temperature is ≥280°C, and the length ratio of the feed section, the melting section, and the metering section in the screw extruder is 1: (1.0-3.0): (1.0-4.0), the feed section temperature is 290-310°C, the melting section temperature is 300-310°C, and the metering section temperature is 280-295°C.

[0105] Step 4: The extruded melt is distributed to the melt pipes of each spinning manifold 2 through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly 1 through a metering pump and is filtered through the filter screen in the spinning assembly 1. The melt is ejected from the spinneret 4 to obtain a melt stream. The number of spinneret holes in the spinneret 4 is 72 to 300; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.0 to 3.0; the filter screen accuracy of the filter screen in the spinning assembly 1 is 5 to 30 μm to improve the uniformity of the filament body. A biphenyl temperature of 295 to 305°C is used to maintain good melt fluidity and pressure.

[0106] Step 5: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by side blowing to obtain the wire body. The side blowing temperature is 18-25°C, the wind speed is 0.4-0.6m / s, and the humidity is 50-70%. During the slow cooling treatment, a heating cover 3 with a temperature of 300-330°C and a heat insulation cylinder 5 with a height of 200-400mm are used.

[0107] Step 6: After the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips. Specifically, oil is applied on the surface of the filament body, and then stretched, shaped and wound; wherein the stretching and shaping are completed by six pairs of rollers; the temperature of the first pair of rollers is 80-95°C, the speed is 300-600 m / min, the temperature of the second pair of rollers is 100-135°C, the speed is 300-600 m / min, the temperature of the third pair of rollers is 100-135°C, the speed is 1400-1 The temperature of the fourth pair of rollers is 230-255°C, and the speed is 2500-2700 m / min, the temperature of the fifth pair of rollers is 230-255°C, and the speed is 2400-2600 m / min, and the sixth pair of rollers is not heated, and the speed is 2000-2600 m / min; the parameters of stretching and shaping are: total stretching multiple is 5-6.2; total relaxation rate is 7-9%, and winding is carried out at a winding speed of 2000-4000 m / min to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips.

[0108] The polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips have a fineness of 350-2220 dtex.

[0109] The breaking strength of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is greater than or equal to 7.8 cN / dtex.

[0110] The coefficient of variation of the breaking strength of the polyester industrial filament prepared from the industrial tail gas coal-based polyester chips is less than or equal to 3.0%.

[0111] The breaking elongation of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is 18-24%.

[0112] When used to prepare polyester industrial filament for safety belts, the specific steps are:

[0113] Step 1: Add PTA, EG prepared from industrial tail gas, catalyst preparation liquid, and 1-5 ppm acetic acid inhibitor into the slurry preparation system, and prepare a slurry with a molar ratio of EG:PTA of 1.0-1.3 under stirring, wherein the antimony content in the catalyst preparation liquid is 150-180 ppm; then, the prepared slurry is sent into the esterification reactor through a slurry delivery pump, and stirred at a pressure of 0.06-0.1 MPa and a temperature of 253-273° C. The initial esterification product can be obtained; then the initial esterification product is transported to a pre-polycondensation reactor with a vacuum degree of 8-11 KPa and a temperature of 260-280° C. through a pressure difference to carry out a pre-polycondensation reaction to obtain a polyester prepolymer; then the prepolymer is transported to a reactor with a vacuum degree of 150-250 Pa and a temperature of 272-293° C. through a prepolymer transport pump to carry out a final polycondensation reaction to obtain a polyester melt; finally, the polyester melt is cooled and granulated to obtain 0.6-0.8 dL / g PET polyester chips.

[0114] Step 2, placing the prepared 0.6-0.8dL / g PET polyester chips in a reactor of a batch polymerization reactor, stirring under a condition where the vacuum degree is less than or equal to 20pa, and uniformly raising the temperature in the reactor to 90-120°C and heating for 2-10h by heating the heat transfer oil pipe, and then continuing to heat to 130-180°C and heating for 5-17h to obtain pre-crystallized chips, and then continuing to heat the temperature in the reactor to 200-240°C by heating the heat transfer oil pipe, and continue heating for 27-33 hours, so that the viscosity of the polyester chips is increased from 0.6-0.8dl / g to 1.00-1.2dL / g after solid phase polymerization, and the moisture content of the final high-viscosity chips is less than or equal to 15ppm.

[0115] Step 3, conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw aspect ratio is 24-33, the screw outlet temperature is ≥280°C, and the length ratio of the feed section, the melting section, and the metering section in the screw extruder is 1: (1.0-3.0): (1.0-4.0), the feed section temperature is 290-310°C, the melting section temperature is 300-310°C, and the metering section temperature is 280-295°C.

[0116] Step 4: The extruded melt is distributed to the melt pipes of each spinning manifold 2 through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly 1 through a metering pump and is filtered through the filter screen in the spinning assembly 1. The melt is ejected from the spinneret 4 to obtain a melt stream. The number of spinneret holes in the spinneret 4 is 72-192; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; the filter screen accuracy of the filter screen in the spinning assembly 1 is 5-30 μm to improve the uniformity of the filament body. A biphenyl temperature of 295-305°C is used to maintain good melt fluidity and pressure.

[0117] Step 5: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by side blowing to obtain the wire body. The side blowing temperature is 18-25°C, the wind speed is 0.4-0.6m / s, and the humidity is 50-70%. During the slow cooling treatment, a heating cover 3 with a temperature of 300-330°C and a heat insulation cylinder 5 with a height of 300-500mm are used.

[0118] Step 6: After the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips. Specifically, oil is applied on the surface of the filament body, and then stretched, shaped and wound; wherein the stretching and shaping is completed by five pairs of rollers; the temperature of the first pair of rollers is 85-100°C, the speed is 300-500 m / min, the temperature of the second pair of rollers is 110-140°C, the speed is 300-500 m / min, and the temperature of the third pair of rollers is The temperature of the fourth pair of rollers is 100-140°C, the speed is 1200-1500 m / min, the temperature of the fourth pair of rollers is 220-250°C, the speed is 2300-2600 m / min, the fifth pair of rollers is not heated, and the speed is 2300-4000 m / min; the parameters of stretching and shaping are: total stretching multiple is 5-6.5; total relaxation rate is 1-5%, and winding is carried out at a winding speed of 2000-4000 m / min to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips.

[0119] The polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips have a fineness of 555-2220 dtex.

[0120] The breaking strength of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is greater than or equal to 7.9 cN / dtex.

[0121] The coefficient of variation of the breaking strength of the polyester industrial filament prepared from the industrial tail gas coal-based polyester chips is less than or equal to 3.0%.

[0122] The breaking elongation of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is 11.5-16.5%.

[0123] The intermediate elongation of the polyester industrial filaments prepared from the industrial tail gas coal-based polyester chips is 5-7%.

[0124] Example 1

[0125] Polyester industrial filament for tire cord fabric is a high modulus low shrinkage yarn. The preparation steps of the polyester industrial filament used are as follows:

[0126] Step 1, PTA, EG prepared from industrial tail gas, catalyst preparation liquid, and 2.5ppm acetic acid inhibitor are added to a slurry preparation system, and a slurry with a molar ratio of EG:PTA of 1.06 is prepared under stirring, wherein the catalyst antimony content is 180ppm; the prepared slurry is then sent to an esterification reactor through a slurry delivery pump, and stirred at a pressure of 0.06-0.08MPa and a temperature of 258-273°C to obtain an esterification primary product; the esterification primary product is then transported to a pre-polycondensation reactor with a vacuum degree of 9.5KPa and a temperature of 269-277°C through a pressure difference to perform a pre-polycondensation reaction to obtain a polyester prepolymer; the prepolymer is then transported to a pre-polycondensation reactor with a vacuum degree of 200Pa and a temperature of 274-293°C through a prepolymer delivery pump to perform a final polycondensation reaction to obtain a polyester melt; and finally, the polyester melt is cooled and granulated to obtain 0.67dL / g PET polyester chips.

[0127] Step 2, placing the industrial tail gas coal-based polyester chips with a viscosity of 0.67 dl / g in an intermittent drum reactor, that is, in an intermittent solid-phase polymerization reactor, and rotating it under a vacuum of 10 Pa, and then heating the temperature in the reactor to 100°C and heating for 3 hours by heating the heat transfer oil pipe, and then continue to heat it to 160°C and heat it for 6 hours to obtain pre-crystallized sheets, and then continue to heat the temperature in the reactor to 223°C by heating the heat transfer oil pipe, and continue to heat it for 30 hours, so that the viscosity of the polyester chips is increased from 0.67 dl / g to 1.13 dL / g after solid-phase polymerization, and high-viscosity chips are formed.

[0128] Step 3, the high-viscosity slices after solid phase polymerization are transported to a screw extruder, and then the melt is extruded through the screw extruder, wherein the screw diameter of the screw extruder is 130 mm, and the length and temperature of the feed section, the length and temperature of the melting section, the length and temperature of the metering section, and the screw outlet temperature are shown in Table 1.

[0129] Step 4: The extruded melt is distributed to the melt pipes of each spinning manifold 2 through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly 1 through a metering pump and is filtered through the filter screen in the spinning assembly 1. The melt is ejected from the spinneret 4 to obtain a melt stream. The number of spinneret holes in the spinneret 4 is shown in Table 2; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 1.3, and the microporous channel length refers to the length of the spinneret hole corresponding to the forward direction of the melt; the maximum accuracy of the filter screen in the spinning assembly 1 is 25μm, which refers to the maximum accuracy in the four-layer metal filter screen to improve the uniformity of the filament body. A biphenyl temperature of 298°C is used to maintain good melt fluidity and pressure.

[0130] Step 5: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by annular blowing to obtain the filament body. The annular blowing temperature is 60°C, the dynamic pressure is 0.03 kPa, and the humidity is 60%. The temperature of the heating cover 3 in the slow cooling device is 330°C, and the height of the insulation cylinder 5 is 80 mm, so as to improve the phenomenon of large CV value of physical properties and many broken filaments caused by uneven cooling.

[0131] Step 6, after the cooled silk strip body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips. Specifically, oil is applied on the surface of the silk strip body, and then it is stretched, shaped and wound; wherein the stretching and shaping are completed by six pairs of rollers; the temperature of the first pair of rollers is 90°C and the speed is 2911 m / min, the temperature of the second pair of rollers is 95°C and the speed is 4075 m / min, the temperature of the third, fourth and fifth pairs of rollers is 247°C and the speed is 5821 m / min, and the sixth pair of rollers is not heated and the speed is 5600 m / min; the parameters of stretching and shaping are: total stretching multiple is 2.0; total relaxation rate is 3.95%, and winding is carried out at a winding speed of 5600 m / min to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips.

[0132] Example 2

[0133] Preparation steps of polyester industrial filament for sewing thread:

[0134] Step 1, PTA, EG prepared from industrial tail gas, catalyst preparation liquid, and 2.5ppm acetic acid inhibitor are added to a slurry preparation system, and a slurry with a molar ratio of EG:PTA of 1.06 is prepared under stirring, wherein the catalyst antimony content is 180ppm; the prepared slurry is then sent to an esterification reactor through a slurry delivery pump, and stirred at a pressure of 0.06-0.08MPa and a temperature of 258-273°C to obtain an esterification primary product; the esterification primary product is then transported to a pre-polycondensation reactor with a vacuum degree of 9.5KPa and a temperature of 269-277°C through a pressure difference to perform a pre-polycondensation reaction to obtain a polyester prepolymer; the prepolymer is then transported to a pre-polycondensation reactor with a vacuum degree of 200Pa and a temperature of 274-293°C through a prepolymer delivery pump to perform a final polycondensation reaction to obtain a polyester melt; and finally, the polyester melt is cooled and granulated to obtain 0.67dL / g PET polyester chips.

[0135] Step 2, placing the industrial tail gas coal-based polyester chips with a viscosity of 0.67 dl / g in an intermittent drum reactor, that is, in an intermittent solid-phase polymerization reactor, and rotating it under a vacuum of 10 Pa, and then heating the temperature in the reactor to 100°C and heating for 3 hours by heating the heat transfer oil pipe, and then continue to heat it to 160°C and heat it for 6 hours to obtain pre-crystallized sheets, and then continue to heat the temperature in the reactor to 220°C by heating the heat transfer oil pipe, and continue to heat it for 29 hours, so that the viscosity of the polyester chips is increased from 0.67 dl / g to 1.12 dL / g after solid-phase polymerization, and high-viscosity chips are formed.

[0136] Step 3, conveying the high-viscosity slices after solid phase polymerization to a screw extruder, and then extruding the melt through the screw extruder, wherein the screw diameter of the screw extruder is 125 mm, and the length and temperature of the feed section, the length and temperature of the melting section, the length and temperature of the metering section, and the screw outlet temperature are shown in Table 1.

[0137] Step 4: The extruded melt is distributed to the melt pipes of each spinning manifold 2 through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly 1 through a metering pump and is filtered through the filter screen in the spinning assembly 1. The melt is ejected from the spinneret 4 to obtain a melt stream. The number of spinneret holes in the spinneret 4 is shown in Table 2; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 2.0, and the microporous channel length refers to the length of the spinneret hole corresponding to the forward direction of the melt; the maximum accuracy of the filter screen in the spinning assembly 1 is 20μm to improve the uniformity of the filament body. A biphenyl temperature of 296°C is used to maintain good melt fluidity and pressure.

[0138] Step 5: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by side blowing to obtain the wire body. The side blowing temperature is 25°C, the wind speed is 0.5m / s, and the humidity is 60%. The temperature of the heating cover 3 in the slow cooling device is 330°C, and the height of the insulation cylinder 5 is 150mm, so as to improve the phenomenon of large CV value of physical properties and many broken ends and hairy wires caused by uneven cooling.

[0139] Step 6, after the above-mentioned cooled silk strip body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips. Specifically, oil is applied on the surface of the silk strip body, and then it is stretched, shaped and wound; wherein the stretching and shaping are completed by five pairs of rollers; the temperature of the first pair of rollers is 85°C and the speed is 449 meters / minute, the temperature of the second pair of rollers is 115°C and the speed is 456 meters / minute, the temperature of the third pair of rollers is 115°C and the speed is 1464 meters / minute, the temperature of the fourth pair of rollers is 240°C and the speed is 2540 meters / minute, and the fifth pair of rollers is not heated and the speed is 2410 meters / minute; wherein the parameters of stretching and shaping are: the total stretching multiple is 5.66; the total relaxation rate is 5.83%, and the winding is carried out at a winding speed of 2400 meters / minute to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips.

[0140] Example 3

[0141] Preparation steps of polyester industrial filament for airbags:

[0142] Step 1, PTA, EG prepared from industrial tail gas, catalyst preparation liquid, and 2.5ppm acetic acid inhibitor are added to a slurry preparation system, and a slurry with a molar ratio of EG:PTA of 1.06 is prepared under stirring, wherein the catalyst antimony content is 180ppm; the prepared slurry is then sent to an esterification reactor through a slurry delivery pump, and stirred at a pressure of 0.06-0.08MPa and a temperature of 258-273°C to obtain an esterification primary product; the esterification primary product is then transported to a pre-polycondensation reactor with a vacuum degree of 9.5KPa and a temperature of 269-277°C through a pressure difference to perform a pre-polycondensation reaction to obtain a polyester prepolymer; the prepolymer is then transported to a pre-polycondensation reactor with a vacuum degree of 200Pa and a temperature of 274-293°C through a prepolymer delivery pump to perform a final polycondensation reaction to obtain a polyester melt; and finally, the polyester melt is cooled and granulated to obtain 0.67dL / g PET polyester chips.

[0143] Step 2, placing the industrial tail gas coal-based polyester chips with a viscosity of 0.67 dl / g in an intermittent drum reactor, that is, in an intermittent solid-phase polymerization reactor, and rotating it under a vacuum of 10 Pa, and then heating the temperature in the reactor to 100°C and heating for 3 hours by heating the heat transfer oil pipe, and then continue to heat it to 160°C and heat it for 6 hours to obtain pre-crystallized sheets, and then continue to heat the temperature in the reactor to 220°C by heating the heat transfer oil pipe, and continue to heat it for 29 hours, so that the viscosity of the polyester chips is increased from 0.67 dl / g to 1.12 dL / g after solid-phase polymerization, and high-viscosity chips are formed.

[0144] Step 3, the high-viscosity slices after solid phase polymerization are transported to a screw extruder, and then the melt is extruded through the screw extruder, wherein the screw diameter of the screw extruder is 130 mm, and the length and temperature of the feed section, the length and temperature of the melting section, the length and temperature of the metering section, and the screw outlet temperature are shown in Table 1.

[0145] Step 4: The extruded melt is distributed to the melt pipes of each spinning manifold 2 through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly 1 through a metering pump and is filtered through the filter screen in the spinning assembly 1. The melt is ejected from the spinneret 4 to obtain a melt stream. The number of spinneret holes in the spinneret 4 is shown in Table 2; the ratio of the microporous channel length of the spinneret hole to the diameter of the spinneret hole is 2.0, and the microporous channel length refers to the length of the spinneret hole corresponding to the forward direction of the melt; the maximum accuracy of the filter screen in the spinning assembly 1 is 20μm to improve the uniformity of the filament body. A biphenyl temperature of 296°C is used to maintain good melt fluidity and pressure.

[0146] Step 5: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by side blowing to obtain the wire body. The side blowing temperature is 25°C, the wind speed is 0.55m / s, and the humidity is 60%. The temperature of the heating cover 3 in the slow cooling device is 330°C, and the height of the insulation cylinder 5 is 250mm, so as to improve the phenomenon of large CV value of physical properties and many broken ends and hairy wires caused by uneven cooling.

[0147] Step 6: After the cooled filament body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips. Specifically, oil is applied on the surface of the filament body, and then stretched, shaped and wound; wherein the stretching and shaping is completed by six pairs of rollers; the temperature of the first pair of rollers is 85°C and the speed is 441 m / min, the temperature of the second pair of rollers is 120°C and the speed is 542 m / min, the temperature of the third pair of rollers is 120°C and the speed is The temperature of the fourth pair of rollers is 237°C and the speed is 2603 m / min, the temperature of the fifth pair of rollers is 237°C and the speed is 2500 m / min, and the sixth pair of rollers is not heated and the speed is 2400 m / min; wherein, the parameters for stretching and shaping are: the total stretching multiple is 5.9; the total relaxation rate is 8.46%, and the winding forming is carried out at a winding speed of 2400 m / min to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips.

[0148] Example 4

[0149] Preparation steps of polyester industrial filament for seat belts:

[0150] Step 1, PTA, EG prepared from industrial tail gas, catalyst preparation liquid, and 2.5ppm acetic acid inhibitor are added to a slurry preparation system, and a slurry with a molar ratio of EG:PTA of 1.06 is prepared under stirring, wherein the catalyst antimony content is 180ppm; the prepared slurry is then sent to an esterification reactor through a slurry delivery pump, and stirred at a pressure of 0.06-0.08MPa and a temperature of 258-273°C to obtain an esterification primary product; the esterification primary product is then transported to a pre-polycondensation reactor with a vacuum degree of 9.5KPa and a temperature of 269-277°C through a pressure difference to perform a pre-polycondensation reaction to obtain a polyester prepolymer; the prepolymer is then transported to a pre-polycondensation reactor with a vacuum degree of 200Pa and a temperature of 274-293°C through a prepolymer delivery pump to perform a final polycondensation reaction to obtain a polyester melt; and finally, the polyester melt is cooled and granulated to obtain 0.67dL / g PET polyester chips.

[0151] Step 2, placing the industrial tail gas coal-based polyester chips with a viscosity of 0.67 dl / g in an intermittent drum reactor, that is, in an intermittent solid-phase polymerization reactor, and rotating it under a vacuum of 10 Pa, and then heating the temperature in the reactor to 100°C and heating for 3 hours by heating the heat transfer oil pipe, and then continue to heat it to 160°C and heat it for 6 hours to obtain pre-crystallized sheets, and then continue to heat the temperature in the reactor to 223°C by heating the heat transfer oil pipe, and continue to heat it for 30 hours, so that the viscosity of the polyester chips is increased from 0.67 dl / g to 1.13 dL / g after solid-phase polymerization, and high-viscosity chips are formed.

[0152] Step 3, the high-viscosity slices after solid phase polymerization are transported to a screw extruder, and then the melt is extruded through the screw extruder, wherein the screw diameter of the screw extruder is 130 mm, and the length and temperature of the feed section, the length and temperature of the melting section, the length and temperature of the metering section, and the screw outlet temperature are shown in Table 1.

[0153] Step 4: The extruded melt is distributed to the melt pipes of each spinning manifold 2 through the melt main pipe to form a spinning melt. The spinning melt enters the spinning assembly 1 through a metering pump and is filtered through the filter screen in the spinning assembly 1. The melt is ejected from the spinneret 4 to obtain a melt stream. The number of spinnerets in the spinneret 4 is shown in Table 2; the ratio of the microporous channel length of the spinneret to the diameter of the spinneret is 2.0, and the microporous channel length refers to the length of the spinneret corresponding to the forward direction of the melt; the maximum accuracy of the filter screen in the spinning assembly 1 is 25 μm to improve the uniformity of the filament body. A biphenyl temperature of 296°C is used to maintain good melt fluidity and pressure.

[0154] Step 5: After each group of melt streams are subjected to slow cooling treatment, the melt streams are cooled by side blowing to obtain the wire body. The side blowing temperature is 25°C, the wind speed is 0.55m / s, and the humidity is 60%. The temperature of the heating cover 3 in the slow cooling device is 310°C, and the height of the insulation cylinder 5 is 450mm, so as to improve the phenomenon of large CV value of physical properties and many broken ends and hairy wires caused by uneven cooling.

[0155] Step 6, after the above-mentioned cooled silk strip body enters the spinning tunnel, it is stretched, shaped and wound to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips. Specifically, oil is applied on the surface of the silk strip body, and then it is stretched, shaped and wound; wherein the stretching and shaping are completed by five pairs of rollers; the temperature of the first pair of rollers is 90°C, the drawing speed is 403 meters / minute, the temperature of the second pair of rollers is 120°C, the drawing speed is 413 meters / minute, the temperature of the third pair of rollers is 120°C, the drawing speed is 1314 meters / minute, the temperature of the fourth pair of rollers is 230°C, the drawing speed is 2457 meters / minute, and the fifth pair of rollers is not heated, and the drawing speed is 2400 meters / minute; wherein the parameters of stretching and shaping are: the total stretching multiple is 6.09; the total relaxation rate is 2.34%, and the winding is carried out at a winding speed of 2400 meters / minute to obtain polyester industrial filaments prepared from industrial tail gas coal-based polyester chips.

[0156] Comparative Examples 1-4

[0157] 0.67 dl / g petroleum-based PET chips were used to replace the coal-based chips in Examples 1-4, and the petroleum-based chips were used to produce polyester industrial filaments for different products according to the methods of Examples 1-4. The relevant parameters in the steps are shown in Tables 1-4.

[0158] In Examples 1-4 and Comparative Examples 1-4, the filter screen in the spinning assembly 1 uses a four-layer metal filter screen, which has good high-temperature oxidation resistance, resistance to melt scouring and corrosion, and good structural stability; and the filtering accuracy is reduced layer by layer, which can remove impurities and gel particles that may remain in the coal-based slice melt, prevent clogging of the spinneret holes of the spinning assembly 1, and establish a stable spinning pressure, which is conducive to evenly distributing the melt to all the spinneret holes on the spinning plate, and making the melt have the same flow path, flow rate and pressure. For example, from top to bottom, the accuracy of the first layer of metal filter screen is 20μm or 25μm, the accuracy of the second layer of metal filter screen is 15μm, the accuracy of the third layer of metal filter screen is 10μm, and the accuracy of the fourth layer of metal filter screen is 5μm. The four layers of metal filter screens are pressed into an integrated structure.

[0159] Table 1 Screw extruder related parameters

[0160]

[0161] Table 2 Spinning related parameters 1

[0162]

[0163]

[0164] Table 3 Spinning related parameters II

[0165]

[0166] Table 4 Parameters related to the stretching part

[0167] Serial number Winding speed m / min Total stretch ratio Relaxation rate Example 1 5600 2.00 3.95％ Comparative Example 1 5600 1.97 5.08％ Example 2 2400 5.66 5.83％ Comparative Example 2 2400 5.61 3.38％ Example 3 2400 5.90 8.46％ Comparative Example 3 2400 5.92 8.54％ Example 4 2400 6.09 2.34％ Comparative Example 4 2400 6.14 1.96％

[0168] The relevant performance parameters of the polyester industrial filaments obtained in Examples 1-4 and Comparative Examples 1-4 are shown in Tables 5 to 7.

[0169] Table 5 Relevant performance parameters of polyester industrial filament

[0170]

[0171]

[0172] Table 6 Relevant performance parameters of polyester industrial filament

[0173]

[0174]

[0175] Table 7 Relevant performance parameters of polyester industrial filament

[0176]

[0177] Among them, the fineness, fineness variation coefficient CV, breaking strength, breaking strength, breaking strength variation coefficient CV, breaking elongation, breaking elongation CV, intermediate elongation, and dry heat shrinkage are measured according to GB / T 16604. The oil content is measured according to GB / T6504-NMR. The network degree is measured according to the hook method.

[0178] The relevant performance parameters of the petroleum-based slices used in Comparative Examples 1-4 are shown in Table 8 below, and the relevant performance parameters of the coal-based slices used in Example 3 are also shown in Table 8 below.

[0179] Table 8 Performance comparison of petroleum-based chips and tail gas coal-based chips

[0180]

[0181] The L value and the B value were measured by Lab color analysis.

[0182] Comparative Example 5

[0183] The chip performance can be affected by adjusting the esterification reaction temperature, polycondensation reaction temperature, catalyst dosage and the use of inhibitors, as shown in Table 9.

[0184] Table 9 Performance parameters of industrial tail gas coal-based chips prepared under different polyester reaction process conditions

[0185]

[0186] Among them, viscosity and DEG are determined by GB / T 14190 standard, and the terminal carboxyl group is determined by potentiometric titrator.

[0187] From the data in Table 9, it can be seen that after adding the inhibitor, other properties of the slices did not change much, but the content of diethylene glycol (DEG) decreased significantly. The content of DEG in polyester actually refers to its ether bond content. The existence of ether bonds destroys the regularity of the neat arrangement of macromolecules to a certain extent, making crystallization difficult, and the corresponding fiber strength decreases, and the dry heat shrinkage rate increases; and the ether bonds in diethylene glycol can change the ethylene glycol chain segments in the polyester macromolecule, thereby increasing the ether bonds in the macromolecule. Since the ether bonds are dye-affinity groups, they will affect the dyeing properties of polyester fibers.

[0188] Comparative Example 6

[0189] Compared with Example 4, the only difference in Comparative Example 6 is that the four-layer metal filter is replaced with a three-layer filter structure commonly used for petroleum-based slices, with a felt mesh in the middle and supported by sieve plates at the top and bottom, and the filtration accuracy is 20 μm.

[0190] Comparative Example 7

[0191] Compared with Example 4, the only difference in Comparative Example 7 is that the length ratio of the feeding section, the melting section, and the metering section is 1:1:1, and the lengths of the feeding section, the melting section, and the metering section are all 864 mm.

[0192] The polyester industrial filaments prepared in Comparative Examples 6 and 7 were tested, and the results are shown in Table 10 below. During the preparation of polyester industrial filaments in Comparative Examples 6, 7, Example 4 and Comparative Example 4, the number of broken ends and the amount of hairy fibers were tested and shown in Table 11 below.

[0193] Table 10 Test results of polyester industrial filaments obtained in Comparative Examples 6 and 7

[0194]

[0195] Table 11 Detection data of the number of broken ends and the amount of hair in comparative example 6, comparative example 7, embodiment 4 and comparative example 4

[0196] Serial number Number of beheadings / day Hair content ppm Comparative Example 6 5.8 34 Comparative Example 7 5.2 24 Example 4 2.1 12 Comparative Example 4 0.3 3

[0197] In summary, since the filter screen structure used in Comparative Example 6 is a felt screen, there are relatively more impurities in the process of preparing polyester industrial filaments from coal-based slices, which leads to blockage of the filter structure and rapid pressure rise in the spinning component 1. As the pressure of the component rises, the efficiency of the metering pump decreases, the fineness decreases, the melt is severely degraded, the strength and elongation decrease, and the number of hairy threads and broken ends increases significantly.

[0198] Since oxalic acid is a by-product of the reaction of producing ethylene glycol from waste industrial exhaust gas, and oxalic acid will remain in ethylene glycol, and the boiling point of oxalic acid is 150°C, it cannot be removed in the process tower. Oxalic acid will be discharged at the bottom of the process tower together with the ethylene glycol product and enter the polymerization stage production system. During the polymerization process, an increase in flexible chains will occur, resulting in a decrease in the thermal stability of the polyester product. Therefore, high screw temperature will lead to a large amount of degradation. However, when the temperature is low and the length of the metering section is not increased, the melt fluidity is poor, the mixing is uneven, the spinnability deteriorates, and the stretching uniformity is affected. Therefore, the fineness of Example 7 decreases, the fineness CV increases, the strength and elongation decrease, the strength CV increases, and the number of filaments and broken ends increases significantly.

[0199] The present application controls the end carboxyl content, characteristic viscosity, and viscosity increase of coal-based chips, appropriately lengthens the melting section or metering section to extend the residence time, and sets a multi-layer metal filter, so that the performance parameters of polyester industrial filaments prepared from coal-based chips are closer to those of polyester industrial filaments prepared from petroleum-based chips.

[0200] The above embodiments are only used to illustrate the technical solution of the present application but not to limit it. The present application is described in detail with reference to the preferred embodiments. It should be understood by those skilled in the art that the technical solution of the present application can be modified or replaced by equivalents without departing from the spirit and scope of the technical solution of the present application, and should be included in the scope of the claims of the present application.

Claims

1. A method for producing polyester chips and polyester industrial filaments by using industrial tail gas to produce ethylene glycol, characterized in that: The steps include: Step 1, adding PTA, EG obtained from industrial tail gas, catalyst preparation liquid, and 1-5 ppm acetic acid inhibitor into a slurry preparation system, and preparing a slurry with a molar ratio of EG:PTA of 1.0-1.3 under stirring; conveying the slurry to an esterification reactor to obtain an esterification initial product; conveying the esterification initial product to a pre-polycondensation reactor for pre-polycondensation reaction to obtain a polyester prepolymer; performing a final polycondensation reaction on the polyester prepolymer to obtain a polyester melt; cooling and granulating the polyester melt to obtain 0.6-0.8 dL / g PET polyester chips; Step 2, placing the prepared 0.6-0.8 dl / g PET polyester chips in a reactor of a batch polymerization reactor to obtain 1.00-1.2 dL / g PET polyester chips; Step 3, conveying 1.00-1.2 dL / g of PET polyester chips to a screw extruder, and extruding the melt through the screw extruder; Step 4: The melt extruded by the screw extruder is distributed to the spinning manifold to form a spinning melt. The spinning melt is filtered and ejected from the spinneret at 295-305° C. to obtain a melt flow. Step 5, subjecting the melt flow to a slow cooling treatment, and then cooling the melt flow by means of annular blowing or side blowing to obtain a wire body; Step 6: After the cooling, the filament body enters the spinning tunnel for stretching, shaping and winding to obtain polyester industrial filaments prepared from coal-based polyester chips.

2. The method according to claim 1, characterized in that The catalyst formulation liquid is a catalyst having an antimony content of 150 to 180 ppm; And / or, the pressure of the esterification reaction kettle is set to 0.06-0.1Mpa, and the temperature is set to 253-273°C; And / or, the vacuum degree of the preliminary polycondensation reaction is 8-11 KPa, and the temperature is 260-280°C; and / or, the vacuum degree of the final polycondensation reaction is 150-250 Pa, and the temperature is 272-293°C.

3. The method according to claim 1, characterized in that: The batch polymerization reactor is stirred under the condition that the vacuum degree in the reactor is less than or equal to 20 Pa, and the temperature in the reactor is uniformly raised to 90-120° C. and heated for 2-10 hours by heating the heat transfer oil pipe, and then continued to be heated to 130-180° C. and heated for 5-17 hours to obtain a pre-crystallized sheet, and then continued to be uniformly heated to 200-240° C. and continued to heat for 27-33 hours, so that the viscosity of the polyester chips is increased from 0.6-0.8 dl / g to 1.00-1.2 dL / g after solid phase polymerization, and the moisture content of the final high-viscosity chips is less than or equal to 15 ppm.

4. The method according to claim 1, characterized in that The screw outlet temperature of the screw extruder is ≥280°C; and / or the length ratio of the feed section, melting section and metering section of the screw extruder is 1:(1.0-3.0):(1.0-4.0).

5. The method according to claim 1, characterized in that The filtration adopts a multi-layer metal filter screen, in which the filtration accuracy decreases layer by layer along the traveling direction of the spinning melt, and the spinning melt is evenly distributed to the spinneret holes.

6. The method according to claim 5, characterized in that The ratio of the micropore channel length of the spinneret hole to the diameter of the spinneret hole is 1.0 to 3.0; and / or the filtering accuracy is 20 to 30 μm.

7. The method according to claim 1, characterized in that The slow cooling treatment is completed by a heating cover with a temperature of 300-330°C and an insulating cylinder with a height of 50-500mm; the ring blowing temperature is 50-70°C, the dynamic pressure is 0.02-0.06kPa, and the humidity is 50-70%; the side blowing temperature is 18-25°C, the wind speed is 0.4-0.6m / s, and the humidity is 50-70%.

8. The method according to claim 1, characterized in that: The parameters of the stretch setting include: The pulling speed is 300-4000 m / min; the total stretching multiple is 2.0-6.5; the setting temperature is 230-260°C; the total relaxation rate is 1.6-9%; and the winding speed is 2000-7000 m / min.

9. The method according to any one of claims 1 to 8, characterized in that: The terminal carboxyl content of the polyester chips made from industrial tail gas is 25 to 30 mol / t; And / or, the color value L of the polyester chips produced from industrial tail gas is ≥79; And / or, the color value b of the polyester chips produced from industrial tail gas is 1.5±2.0; And / or, the moisture content of the polyester chips produced from industrial tail gas is ≤0.40%; And / or, the content of diethylene glycol in the polyester chips produced from industrial tail gas is 0.80-1.00%.

10. The method according to any one of claims 1 to 8, characterized in that: The polyester industrial filament has a fineness of 167 to 3300 dtex; and / or, the breaking strength of the polyester industrial filament is ≥7.15 cN / dtex; And / or, the coefficient of variation of the breaking strength of the polyester industrial filament is ≤4.0%; And / or, the elongation at break of the polyester industrial filament is 11.5-24%; And / or, the intermediate elongation of the polyester industrial filament is 5-10%.

11. A polyester industrial filament prepared by the method according to any one of claims 1 to 10.

12. The polyester industrial filament according to claim 11, characterized in that: The polyester industrial filament is used for preparing tire cord fabric, safety belt, air bag or sewing thread.

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