Method for using ethylene glycol prepared from industrial exhaust gas to produce polyester chips and further prepare polyester industrial filaments, and prepared polyester industrial filaments

Abstract

A method for using ethylene glycol prepared from industrial exhaust gas to produce polyester chips and further prepare polyester industrial filaments, and prepared polyester industrial filaments. Specifically, ethylene glycol which is produced from industrial exhaust gas and has an ethylene glycol content of greater than or equal to 99.9% is selected as a raw material, and a slurry in which the molar ratio of EG to PTA is 1.0-1.3 is formulated; coal-based PET chips having an intrinsic viscosity of 0.6-0.8 dl / g and a carboxyl terminal group content of 25-30 mol / t are synthesized from an antimony-containing catalyst and 1-5 ppm of an acetic-acid-based inhibitor, and are then tackified to obtain coal-based high-viscosity chips having a viscosity of 1.00-1.2 dl / g, and the chips are then spun on an industrial yarn production line; the temperature of a screw is controlled, and the lengths of a feeding section and a metering section are adjusted, so that the chips are fully melted while the melt is protected from further chain scission along with thermal degradation due to the inclusion of a small amount of flexible chains, and the stability of the outlet pressure of the screw is also ensured; a multi-layer filter screen structure is selected for a spinning assembly, so as to ameliorate adverse effects caused by the presence of many impurities in the coal-based chips; and drawing and setting conditions are optimized and adjusted, so that the physical properties, fuzziness and spinnability all meet requirements.

Description

A method for producing polyester chips and preparing polyester industrial filaments by using industrial tail gas to produce ethylene glycol and the prepared polyester industrial filaments

[0001] Cross-reference to Related Applications

[0002] The present disclosure claims priority to the Chinese patent application No. 202411326908.1, filed on September 23, 2024, entitled "A method for producing polyester chips and preparing polyester industrial filaments by using industrial tail gas to produce ethylene glycol and the prepared polyester industrial filaments", to the State Intellectual Property Office of China, the entire contents of which are incorporated herein by reference. TECHNICAL FIELD

[0003] The present application belongs to the field of chemical fibers, and specifically relates to a method for producing polyester chips and preparing polyester industrial filaments by using industrial tail gas to produce ethylene glycol and the prepared polyester industrial filaments. BACKGROUND

[0004] About 94% of ethylene glycol on the market is used as a polyester raw material. The traditional production of ethylene glycol is to use a petroleum ethylene route as a production process. Due to the limitation of the lack of oil resources in China, this production process is greatly restricted in terms of resource utilization and production cost. However, China is rich in coal resources, so the process of synthesizing ethylene glycol based on coal-based synthesis gas has a wide range of raw material sources and low prices, and is high in technical and economic efficiency.

[0005] Chemical fiber production relies too much on petroleum chemicals, resulting in a large consumption of non-renewable resources such as oil, causing resource depletion and environmental pollution. According to reports, the world's oil resources can be exploited for about 40 years, while China's oil resources can be exploited for no more than 30 years.

[0006] Compared with petroleum-based ethylene glycol, using industrial tail gas as raw material to produce ethylene glycol not only realizes the resource utilization of tail gas, but also is environmentally friendly and low in cost, and has strong market competitiveness. However, in the prior art, the ethylene glycol prepared by using industrial tail gas as raw material has oxalic acid residues in the ethylene glycol due to reaction by-products, which cannot be completely removed from the top of the process column when entering the polyester production process, and then when entering the subsequent polycondensation process, the degree of polymerization increases and thermal degradation occurs, which directly reflects on the final analysis index of the polyester, that is, the increase of the terminal carboxyl content. The terminal carboxyl content of the polyester product can reflect the regularity of the polymer chain, which is generally controlled below 30 mol / t. If the terminal carboxyl content rises to more than 35 mol / t, it will cause changes in the processing performance of the polyester product after spinning, mainly the increase of the number of broken filaments, and the strength index of the fiber product will also decrease to different degrees. And a small amount of oxalic acid esterification with ethylene glycol may generate a small amount of flexible chain into the polyester product during the polycondensation reaction, which may further produce chain scission phenomenon with thermal degradation, resulting in sudden filament breakage during spinning, but the spinneret plate surface is very clean.

[0007] In the process of preparing polyester industrial filament from petroleum-based chips, a three-layer filter structure is used in the spinning assembly, with felt net in the middle and screen plate at the top and bottom. In the process of preparing polyester industrial filament from coal-based chips, there are relatively more impurities, and the impact of the melt on the filter net is larger, resulting in filter structure blockage and rapid spinning assembly pressure rise; and the orifice bulging phenomenon easily occurs during spinning, resulting in spinning sticking, broken filaments and many injection filaments.

[0008] Therefore, the present application needs to solve the following technical problems:

[0009] 1) How to use industrial tail gas ethylene glycol as raw material to carry out polyester process to obtain polyester chips;

[0010] 2) How to carry out solid phase tackifying process to improve the intrinsic viscosity of the polyester chips;

[0011] 3) How to ensure that the physical properties and broken filament index of the prepared polyester industrial filament are qualified. SUMMARY

[0012] A method for producing polyester chips and preparing polyester industrial filament by using industrial tail gas to produce ethylene glycol, comprising the following steps:

[0013] Step 1, adding p-phthalic acid (PTA), ethylene glycol (EG) made by industrial tail gas, catalyst preparation solution, 1-5 ppm acetic acid type inhibitor into a slurry preparation system to prepare 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 to perform pre-polycondensation reaction to obtain a polyester prepolymer; performing 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 obtained 0.6-0.8 dl / g PET polyester chips into a reaction kettle of a batch polymerization reactor to obtain 1.00-1.2 dL / g PET polyester chips;

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

[0016] Step 4, distributing the melt extruded by the screw extruder to a spinning beam to form a spinning melt, and spinning the melt from a spinneret after filtration under the condition of 295-305°C to obtain a melt flow;

[0017] Step 5, performing slow cooling treatment on the melt flow, and cooling the melt flow by ring blowing or side blowing to obtain a yarn body;

[0018] Step 6, conveying the cooled yarn body into a spinning duct to perform drawing setting and winding treatment to obtain a coal-based polyester chip prepared polyester industrial filament.

[0019] A polyester industrial filament prepared based on the above method. BRIEF DESCRIPTION OF DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following will briefly introduce the drawings needed to be used in the embodiments. It should be understood that the following drawings only show some embodiments of the present disclosure, and therefore should not be regarded as a limitation on the scope of the present disclosure.

[0021] FIG. 1 is a flow chart of a polyester process in an embodiment of the present application;

[0022] FIG. 2 is a schematic view of the cross-sectional structure of a single hole of a spinneret in an embodiment of the present application;

[0023] FIG. 3 is a schematic view of the partial structure of a spinning assembly in an embodiment of the present application;

[0024] In the figure: spinning assembly 1, spinning beam 2, heating cover 3, spinneret 4, heat insulation cylinder 5; a is the melt flow direction; b is the melt stream out of the filament direction; c is the cooling air direction. DETAILED DESCRIPTION

[0025] The embodiments of the present application will be described in detail below with examples, but those skilled in the art will understand that the following examples are only for illustration of the present application and should not be regarded as limiting the scope of the present application. If the specific conditions are not specified in the examples, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be obtained by commercial purchase.

[0026] The endpoints of the ranges and any values disclosed herein are not limited to the precise values stated. The ranges or values should be construed to be roughly around the ranges or values. The endpoints between each range of values, the endpoints and individual points between ranges of values, and the individual points themselves can be combined with one or more other points or ranges to form new ranges or values that are not expressly mentioned. The term "optional" or "optional" means that it can be included or not included (or can be present or not present). The term "and / or" in the present application is inclusive, for example, "A and / or B" means only A, or only B, or both A and B.

[0027] When the equivalent, concentration, or other value or parameter is expressed in a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, it should be understood that all ranges formed by any pair of an upper range limit or preferred value and any lower range limit or preferred value, whether or not the range is expressly mentioned, are specifically disclosed. For example, when the range "1-5" is disclosed, the described range should be interpreted as including the range "1-4", "1-3", "1-2", "1-2 and 4-5", "1-3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0028] In view of the 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 preparing polyester industrial filaments from industrial tail gas for producing ethylene glycol, and the prepared polyester industrial filaments.

[0029] To solve the above technical problems, the present application realizes the technical scheme as follows:

[0030] The present application provides a method for producing polyester chips and preparing polyester industrial filaments from industrial tail gas for producing ethylene glycol, characterized in that it comprises the following steps:

[0031] Step 1, adding terephthalic acid (PTA), ethylene glycol (EG) made by industrial tail gas, catalyst preparation solution, 1-5 ppm acetic acid inhibitor into a slurry preparation system to prepare a slurry with a molar ratio of EG:PTA of 1.0-1.3 under stirring; conveying the slurry into an esterification reactor to obtain an esterification initial product; conveying the esterification initial product into a pre-polycondensation reactor to perform pre-polycondensation reaction to obtain a polyester prepolymer; performing 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;

[0032] Step 2, placing the obtained 0.6-0.8 dl / g PET polyester chips into a reaction kettle of a batch polymerization reactor to obtain 1.00-1.2 dL / g PET polyester chips;

[0033] Step 3, conveying the 1.00-1.2 dL / g PET polyester chips into a screw extruder to extrude a melt through the screw extruder;

[0034] Step 4, distributing the melt extruded by the screw extruder into a spinning beam to form a spinning melt, and after filtration, the spinning melt is extruded from a spinneret to obtain a melt flow under the condition of 295-305 ℃;

[0035] Step 5, performing slow cooling treatment on the melt flow, and then cooling the melt flow by ring blowing or side blowing to obtain a yarn body;

[0036] Step 6, after cooling, the yarn body enters a spinning duct to perform drawing setting and winding treatment to obtain a coal-based polyester chip prepared polyester industrial filament.

[0037] In one or more embodiments, the catalyst preparation solution is a catalyst with an antimony content of 150-180 ppm;

[0038] And / or, the pressure of the esterification reactor is set to 0.06-0.1 Mpa, and the temperature is set to 253-273 ℃;

[0039] And / or, the vacuum degree of the pre-polycondensation reaction is 8-11 Kpa, and the temperature is 260-280 ℃;

[0040] And / or, the vacuum degree of the final polycondensation reaction is 150-250 Pa, and the temperature is 272-293 ℃.

[0041] In one or more embodiments, the esterification reactor comprises a first esterification kettle and a second esterification kettle, wherein the temperature of the first esterification kettle is set to 258-262 ℃; and the temperature of the second esterification kettle is set to 262-276 ℃.

[0042] In one or more embodiments, the vacuum degree in the reaction kettle of the batch polymerization reactor is less than or equal to 20 Pa, the temperature in the reaction kettle is uniformly raised to 90-120°C by heating the heat conducting oil pipe for 2-10 hours, then continuously raised to 130-180°C for 5-17 hours to obtain pre-crystallized chips, and then continuously uniformly raised to 200-240°C 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 of the final high-viscosity chips is less than or equal to 15 ppm.

[0043] In one or more embodiments, the screw outlet temperature of the screw extruder is ≥ 280°C; and / or, the length ratio of the feeding section, the melting section and the metering section of the screw extruder is 1:(1.0-3.0):(1.0-4.0). Preferably, the length ratio of the feeding section, the melting section and the metering section of the screw extruder is 1:(1.5-2.5):(2.5-4); more preferably, the length ratio of the feeding section, the melting section and the metering section of the screw extruder is 1:(1.8-2.2):(2.8-4).

[0044] In one or more embodiments, the screw diameter of the screw extruder is 75-170 mm, and the screw length-diameter ratio is 24-33.

[0045] In one or more embodiments, the filtration uses a multi-layer metal filter screen, the filtration precision of which decreases layer by layer along the direction of the spinning melt, and the spinning melt is uniformly distributed into the spinneret holes.

[0046] In one or more embodiments, the ratio of the length of the micro-pore channel of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; and / or, the filtration precision is 5-30 μm; preferably, the filtration precision is 20-30 μm.

[0047] In one or more embodiments, the slow cooling treatment is completed by a heating cover with a temperature of 300-330°C and a heat insulation cylinder with a height of 50-500 mm; the circular blowing temperature is 50-70°C, the dynamic pressure is 0.02-0.06 kPa, and the humidity is 50-70%; the side blowing temperature is 18-25°C, the wind speed is 0.4-0.6 m / s, and the humidity is 50-70%.

[0048] In one or more embodiments, the parameters of the drawing and setting include: the drawing speed is 300-4000 meters / minute; the total drawing multiple is 2.0-6.5; the setting temperature is 230°C-260°C; the total relaxation rate is 1.6-9%; and the winding speed is 2000-7000 meters / minute.

[0049] In one or more embodiments, the end carboxyl group content of the industrial off-gas polyester chip is 25-30 mol / t;

[0050] And / or, the color value L of the industrial off-gas polyester chip is ≥79;

[0051] And / or, the color value b of the industrial off-gas polyester chip is 1.5±2.0;

[0052] And / or, the moisture content of the industrial off-gas polyester chip is ≤0.40%;

[0053] And / or, the diethylene glycol content of the industrial off-gas polyester chip is 0.80-1.00%.

[0054] In one or more embodiments, the denier of the polyester industrial filament is 100-3300 dtex, preferably the denier of the polyester industrial filament is 167-3300 dtex;

[0055] And / or, the breaking strength of the polyester industrial filament is ≥7.15 cN / dtex;

[0056] And / or, the coefficient of variation of the breaking strength of the polyester industrial filament is ≤4.0%;

[0057] And / or, the elongation at break of the polyester industrial filament is 11.5-24%;

[0058] And / or, the intermediate elongation of the polyester industrial filament is 5-10%.

[0059] In one or more embodiments, the ethylene glycol content of the industrial off-gas ethylene glycol is greater than or equal to 99%.

[0060] In one or more embodiments, the ethylene glycol content of the industrial off-gas ethylene glycol is greater than or equal to 99.9%.

[0061] The application provides a polyester industrial filament prepared based on the above method.

[0062] In one or more embodiments, the polyester industrial filament is used to prepare tire cord, safety belt, airbag, or sewing thread.

[0063] Compared with the prior art, the application has the following technical effects:

[0064] The application selects industrial tail gas to produce ethylene glycol as raw material, and adjusts the slurry with the molar ratio of EG: PTA being 1.0-1.3, uses the catalyst containing antimony and the acetic acid series inhibitor, synthesizes the coal-based PET chip with the intrinsic viscosity being 0.6-0.8 dl / g and the end carboxyl content being 25-30 mol / t, and obtains the coal-based high-viscosity chip with the intrinsic viscosity being 1.00-1.2 dl / g after tackifying, and then spins on the industrial yarn production line; the screw temperature is controlled, the feeding section and the metering section length are adjusted, the chip is fully melted while ensuring that the melt does not further produce chain scission phenomenon due to the occurrence of thermal degradation and the stability of the screw outlet pressure is ensured; the filter is arranged in the spinning assembly to improve the problem that the spinning assembly pressure rises fast due to the many impurities of the coal-based chip; the stretching and setting conditions are optimized and adjusted, so that the physical properties, the hairiness and the spinnability can all meet the requirements.

[0065] The technical solutions in the embodiments of the application will be clearly and completely described below with reference to the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, rather than all the embodiments. Based on the embodiments in the application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the application.

[0066] The application uses industrial tail gas to produce ethylene glycol with the ethylene glycol content being greater than or equal to 99%, preferably greater than or equal to 99.9%, as raw material, specifically, the ethylene glycol is obtained by recovering the tail gas of a steel plant by the oxalic acid method, the slurry with the molar ratio of EG: PTA being 1.0-1.3 is adjusted, the ethylene glycol antimony with the antimony content being 150-180 ppm is used as the catalyst, the acetic acid series inhibitor with 1-5 ppm is used, the coal-based PET chip with the intrinsic viscosity being 0.6-0.8 dl / g and the end carboxyl content being 25-30 mol / t is synthesized through a five-kettle process, the coal-based chip is tackified to 1.00-1.2 dl / g through a suitable tackifying process, the melting and cooling temperatures matched with the coal-based chip produced from the industrial tail gas are designed, the spinning melt is stably extruded, and the stretching process parameters are optimized to obtain the polyester industrial yarn long filament prepared from the coal-based polyester chip produced from the industrial tail gas with qualified physical properties and hairiness.

[0067] A method for producing polyester chip and preparing polyester industrial yarn long filament from industrial tail gas to produce ethylene glycol, comprising the following steps:

[0068] Step 1, add PTA, EG made from industrial tail gas, catalyst preparation solution, 1-5 ppm acetic acid inhibitor into the slurry preparation system, under the action of stirring, prepare the slurry with the molar ratio of EG:PTA being 1.0-1.3; then pump the prepared slurry into the esterification reactor through the slurry pump, under the pressure of 0.06-0.1 MPa and the temperature of 253-273℃, obtain the esterification initial product; then pump the esterification initial product into the pre-polycondensation reactor through the pressure difference, under the vacuum degree of 8-11 KPa and the temperature of 260-280℃, carry out the pre-polycondensation reaction to obtain the polyester prepolymer; then pump the prepolymer into the final polycondensation reactor through the prepolymer pump, under the vacuum degree of 150-250 Pa and the temperature of 272-293℃, carry out the final polycondensation reaction to obtain the polyester melt; finally, cool and granulate the polyester melt to obtain the 0.6-0.8 dL / g PET polyester chip, as shown in FIG. 1.

[0069] When using EG made from industrial tail gas to react with PTA to prepare polyester chip, the prepared slurry is pumped into the esterification reactor through the slurry pump, the temperature of the first esterification reactor is controlled in the range of 258-262℃, and the temperature of the second esterification reactor is 262-276℃, which is about 3℃ higher than the temperature when using petroleum-based EG, i.e. 2℃ higher than the normal control range, so as to promote the forward reaction. The increase of the esterification temperature in the polyester process will lead to the acceleration of the reaction speed, so the esterification temperature is an important control parameter. Under the condition of a certain molar ratio of EG / PTA, the increase of the reaction temperature will also increase the reaction speed, accelerate the esterification reaction and shorten the time, but at the same time, it will also accelerate the side reactions in the system and increase the content of diethylene glycol (DEG), which will eventually lead to the increase of the DEG content in the chip product, which means that in the polyester production process, the temperature needs to be precisely controlled to ensure the product quality and yield. Otherwise, it will lead to the decrease of the melting point of the product and the deterioration of the color.

[0070] In order to prepare the chip with the same index, by changing the temperature, liquid level, catalyst and other process conditions, the content of the byproduct DEG is correspondingly increased, by selecting the appropriate acetic acid inhibitor and controlling the addition amount in the range of 1-5 ppm, the content of DEG is controlled in the normal range.

[0071] Specifically, the reactor used for the final polycondensation reaction is a horizontal reactor of squirrel cage type, and the vacuum degree is adjusted by adjusting the suction steam amount of the ethylene glycol steam jet pump in control. The reactor jacket is heated by gas phase heat medium, and the gas phase heat medium is generated by heat medium evaporator. The temperature of the entire polymerization section will be from 274℃ to 293℃, and the temperature is one of the important means to control the polymerization degree. If the temperature fluctuates greatly during the entire process, it will affect the fluctuation of the polymerization degree, and too high temperature will also cause the antioxidant capacity of the ester particles to decrease, resulting in the increase of B value, affecting the quality of the final product. In order to ensure the polymerization degree and B value of the product at the same time, a liquid level meter is arranged at each of the inlet and outlet sides of the reactor, and the feed amount of the prepolymer conveying pump is adjusted by the two liquid level values to control the residence time of the material.

[0072] The content of antimony in the catalyst preparation liquid is 150-180 ppm; specifically, ethylene glycol antimony is used as the catalyst for polycondensation reaction in the production process, and the catalyst is controlled between 150-180 ppm when the chip is prepared by using industrial off-gas to prepare ethylene glycol, while the content of antimony in the catalyst preparation liquid used by petroleum-based is 170-200 ppm, and the content of antimony in the catalyst preparation liquid of the present application is averagely reduced by 20 ppm. If the amount of catalyst added is large and other conditions are the same, the polycondensation reaction rate will be fast and the viscosity will be high; if the amount of catalyst added is small and other conditions are the same, the polycondensation reaction rate will decrease and the viscosity will be low.

[0073] The intrinsic viscosity of the polyester chip prepared from industrial off-gas is 0.6-0.8 dl / g.

[0074] The end carboxyl content of the polyester chip prepared from industrial off-gas is 25-30 mol / t.

[0075] The color value L of the polyester chip prepared from industrial off-gas is ≥79.

[0076] The color value b of the polyester chip prepared from industrial off-gas is 1.5±2.0.

[0077] The moisture content of the polyester chip prepared from industrial off-gas is ≤0.40%.

[0078] The diethylene glycol content of the polyester chip prepared from industrial off-gas is 0.80-1.00%.

[0079] Step 2, the prepared 0.6-0.8 dL / g PET polyester chip is placed in the reaction kettle of the batch polymerization reactor, and stirring is carried out under the condition that the vacuum degree is less than or equal to 20 pa. The temperature in the reaction kettle is uniformly raised to 90-120°C by heating the heat conducting oil pipe, and heated for 2-10 hours. Then the temperature in the reaction kettle is uniformly raised to 130-180°C by heating the heat conducting oil pipe, and heated for 5-17 hours to obtain a pre-crystallized chip. Then the temperature in the reaction kettle is uniformly raised to 200-240°C by heating the heat conducting oil pipe, and continues to heat for 27-33 hours, so that the viscosity of the polyester chip is increased from 0.6-0.8 dl / g to 1.00-1.2 dL / g after solid-phase polymerization. The moisture of the final high-viscosity chip is less than or equal to 15 ppm.

[0080] Step 3, the high-viscosity chip after solid-phase polymerization is transported to a screw extruder, and then the melt is extruded through the screw extruder. The screw diameter of the screw extruder is 75-170 mm, and the screw length-diameter ratio is 24-33, and the screw outlet temperature is ≥280°C.

[0081] Because oxalic acid is a by-product of the reaction of industrial tail gas to produce ethylene glycol, and oxalic acid remains in ethylene glycol, the boiling point of oxalic acid is 150°C, which cannot be removed in the process column, and will be discharged with the ethylene glycol product at the bottom of the process column into the polymerization section production system. In the polymerization process, the phenomenon of increasing flexible chain will occur, which will cause the decrease of the thermal stability of the polyester product. Therefore, the length of each functional zone of the screw used for spinning of the industrial tail gas coal-based chip should be different from that of the petroleum-based chip. According to the bulk density and melting time of the dried industrial tail gas coal-based chip, by optimizing each functional section, such as increasing the length of the melting section and the metering section, and reducing the length of the feeding section, the stability of the screw extrusion amount and the extrusion pressure can be ensured, so as to ensure the normal spinning production.

[0082] Because oxalic acid is a by-product of the reaction of industrial tail gas to produce ethylene glycol, and oxalic acid remains in ethylene glycol, the boiling point of oxalic acid is 150°C, which cannot be removed in the process column, and will be discharged with the ethylene glycol product at the bottom of the process column into the polymerization section production system. In the polymerization process, the phenomenon of increasing flexible chain will occur, which will cause the decrease of the thermal stability of the polyester product. Therefore, the length of each functional zone of the screw used for spinning of the industrial tail gas coal-based chip should be different from that of the petroleum-based chip. According to the bulk density and melting time of the dried industrial tail gas coal-based chip, by optimizing each functional section, such as increasing the length of the melting section and the metering section, and reducing the length of the feeding section, the stability of the screw extrusion amount and the extrusion pressure can be ensured, so as to ensure the normal spinning production.

[0083] Step 4, the extruded melt is distributed to the melt duct of each spinning beam 2 through the melt manifold 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 sprayed from the spinneret 4 to obtain a melt stream, as shown in Figure 3. The spinning beam 2 comprises the metering pump and the spinning assembly 1, and the spinning assembly 1 comprises the filter screen and the spinneret 4. The number of the spinneret holes in the spinneret 4 is 28-960; the ratio of the length of the micro-pore channel of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0, as shown in Figure 2, L1 is the length of the micro-pore channel, and D1 is the diameter of the spinneret hole; the filter screen precision of the filter screen in the spinning assembly 1 is 5-30 μm, preferably 20-30 μm, so as to improve the uniformity of the yarn body. The spinning beam 2 is heated using a biphenyl temperature of 295-305 ℃, so as to maintain good melt fluidity and pressure.

[0084] The industrial tail gas-based tackifying chip has many impurities and is easy to degrade, and the orifice bulging phenomenon is prone to occur in the spinning process, which leads to many spinning sticking, hairiness and jet yarns. A suitable assembly filter is designed according to the characteristics of the industrial tail gas-based tackifying chip, and a multi-layer metal filter screen structure is used to improve the problem of rapid pressure rise of the assembly caused by many impurities of the coal-based chip, and to reduce the shear rate of the melt passing through the spinneret hole, so that the bulging phenomenon is obviously inhibited, the defects and jet yarns are greatly reduced, and the spinnability is greatly improved. At present, the highest spinning speed can reach 5600 m / min, which has reached the same level of petroleum-based melt spinning.

[0085] Step 5, after the slow cooling treatment of each group of melt streams, the melt streams are cooled by the form of ring blowing or side blowing to obtain the yarn body. The temperature of the ring blowing is 50-70℃, the dynamic pressure is 0.02-0.06kPa, and the humidity is 50-70%; the temperature of the side blowing is 18-25℃, the wind speed is 0.4-0.6m / s, and the humidity is 50-70%. The slow cooling device includes a heating cover 3 and an insulation cylinder 5, and the melt streams sprayed from the spinneret 4 enter the heating cover 3 and the insulation cylinder 5 in sequence; the temperature control point of the heating cover 3 is 300-330℃ to maintain good heat preservation effect. The function of the heating cover 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 rapidly. On the one hand, it can prevent the melt from breaking; on the other hand, it can eliminate the internal stress of macromolecules and improve the fiber stretching performance. The insulation cylinder 5 has a height of 50-500mm, i.e. the travel distance of the melt streams in the insulation cylinder 5 is 50-500mm of the height of the insulation cylinder 5, so as to improve the phenomenon of large CV value and many broken ends caused by uneven cooling. The melt streams from the insulation cylinder 5 enter the ring blowing or side blowing device. The function of the insulation cylinder 5 is to prolong the length of the windless zone, on the one hand to reduce the impact of the airflow below on the spinneret 4 and the un-solidified melt, and on the other hand to delay the cooling, so that the spinning stretching is completed before the melt solidifies, which is beneficial to the generation of straight-chain macromolecules and the uniformization of the orientation degree of each part. The length of the insulation cylinder 5 can be changed, which has a great influence on the breaking elongation of the fiber.

[0086] Step 6, after the yarn body is cooled, the yarn body is stretched, set and wound to obtain the polyester industrial filament prepared from the industrial tail gas coal-based polyester chip.

[0087] The industrial tail gas coal-based polyester chip prepared polyester industrial filament has a fineness of 100-3300dtex, preferably 167-3300dtex.

[0088] The industrial tail gas coal-based polyester chip prepared polyester industrial filament has a breaking strength greater than or equal to 7.15cN / dtex.

[0089] The industrial tail gas coal-based polyester chip prepared polyester industrial filament has a breaking strength variation coefficient less than or equal to 4.0%.

[0090] The industrial tail gas coal-based polyester chip prepared polyester industrial filament has an elongation at break of 11.5-24%.

[0091] The intermediate elongation of the terephthalic acid industrial filament prepared from the coal-based polyester chip prepared from the industrial tail gas is 5-10%.

[0092] The present application uses industrial tail gas as raw material to prepare ethylene glycol. Since by-products oxalic acid will remain in the product ethylene glycol, it cannot be completely removed from the top of the process column when entering the polyester production process, a small amount of oxalic acid will esterify with ethylene glycol, and a small amount of flexible chain may be generated in the polycondensation reaction to enter the polyester finished product, and after tackifying, a coal-based tackifying chip with a viscosity of 1.00-1.2 dl / g is obtained, which is spun on the existing industrial yarn production line; the screw temperature is controlled at 280-310℃, so that the chip is fully melted while ensuring that the melt does not further produce chain scission due to the presence of a small amount of flexible chain and the stability of the screw outlet pressure; the spinning assembly 1 is selected to have a multi-layer metal filter screen structure of 20-30μm to improve the problem of rapid pressure rise of the spinning assembly 1 caused by the high impurity content of the coal-based chip; the stretching and setting conditions are optimized and adjusted to meet the requirements of physical properties, lint and spinnability. The production process parameters suitable for coal-based chips are summarized, which can stabilize the coal-based terephthalic acid industrial filament, and the various indicators of the coal-based terephthalic acid industrial filament are close to those of the same specification petroleum-based filament.

[0093] The purity of ethylene glycol is close to the lower limit of the index, only 99.92%, which is significantly lower than the petroleum-based 99.99%; the moisture content is 3.4 times that of petroleum-based ethylene glycol, which increases the burden on the process column and also increases the burden on the vacuum, which will affect the viscosity and color value of the chip. Considering this influence, the esterification temperature is increased during the trial period, the liquid level of the polymerization section is increased, the residence time is increased, and the possible fluctuations are compensated; the increase in ash content will also increase the impurities in the entire system and affect the color value of the product, resulting in a decrease in L value. The ultraviolet light transmittance of the ethylene glycol product prepared from industrial tail gas is low, mainly due to the coking material produced during the rectification process entering the product. These impurities ultimately affect the L value of the product in the polyester synthesis. In view of the possible influence, the reaction temperature in the polymerization section is reduced to compensate for the color value change caused by high temperature.

[0094] The terephthalic acid industrial filament prepared from the coal-based polyester chip prepared from the industrial tail gas can be used to prepare tire cord, sewing thread, airbag or safety belt.

[0095] When used to prepare terephthalic acid industrial filament for tire cord, the steps are specifically as follows:

[0096] Step 1, in the slurry preparation system, add PTA, industrial tail gas to EG, catalyst preparation solution, 1-5ppm acetic acid inhibitor, under the action of stirring, prepare the slurry with the molar ratio of EG:PTA being 1.0-1.3, wherein the content of antimony in the catalyst preparation solution is 150-180ppm; then pump the prepared slurry into the esterification reactor through the slurry pump, and under the conditions of 0.06-0.1MPa pressure and 253-273℃ temperature, carry out stirring to obtain the esterification initial product; then transport the esterification initial product to the pre-polycondensation reactor through the pressure difference, and under the conditions of 8-11KPa vacuum degree and 260-280℃ temperature, carry out pre-polycondensation reaction to obtain polyester prepolymer; then transport the prepolymer to the final polycondensation reactor through the prepolymer pump, and under the conditions of 150-250Pa vacuum degree and 272-293℃ temperature, carry out final polycondensation reaction to obtain polyester melt; finally, the polyester melt is cooled and granulated to obtain 0.6-0.8dL / g PET polyester chip.

[0097] Step 2, place the prepared 0.6-0.8dL / g PET polyester chip in the reaction kettle of the batch polymerization reactor, and under the condition of less than or equal to 20pa vacuum degree, carry out stirring, and by the way of heating the heat conducting oil pipe, uniformly heat the temperature in the reaction kettle to 90-120℃ and heat for 2-10h, then continue to heat to 130-180℃ and heat for 5-17h to obtain pre-crystallized chip, then continue to heat the temperature in the reaction kettle to 200-240℃ by the way of heating the heat conducting oil pipe, and continue to heat for 27-33h, so that the viscosity of the polyester chip is increased from 0.6-0.8dl / g to 1.00-1.2dL / g after solid phase polymerization, and the moisture of the final high-viscosity chip is less than or equal to 15ppm.

[0098] Step 3, transport the high-viscosity chip after solid phase polymerization to the screw extruder, and then extrude the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170mm, the screw length-diameter ratio is 24-33, the screw outlet temperature is ≥280℃, and the length ratio of the feeding section, the melting section and the metering section in the screw extruder is 1:(1.0-3.0):(1.0-4.0), the feeding section temperature is 290-310℃, the melting section temperature is 300-310℃, and the metering section temperature is 280-295℃.

[0099] Step 4, the extruded melt is distributed to the melt duct of each spinning beam 2 through the melt manifold 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 sprayed 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 length of the micro-pore channel of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; the filter screen precision of the filter screen in the spinning assembly 1 is 5-30 μm to improve the uniformity of the yarn body. The temperature of the biphenyl is 295-305 ℃ to maintain good melt fluidity and pressure.

[0100] Step 5, after the slow cooling treatment of the melt stream, the melt stream is cooled in the form of ring blowing to obtain a yarn body. The temperature of the ring blowing is 50-70 ℃, the dynamic pressure is 0.02-0.06 kPa, and the humidity is 50-70%. The heating cover 3 has a temperature of 300-330 ℃ and the heat insulation cylinder 5 has a height of 50-120 mm during the slow cooling treatment.

[0101] Step 6, after the yarn body is cooled, the yarn body is stretched, set and wound in the spinning duct to obtain the industrial polyester filament prepared from the industrial tail gas coal-based polyester chip. Specifically, the yarn body is oiled, then stretched, set and wound. The stretching and setting are completed by six pairs of rollers. The temperature of the first pair of rollers is 80-95 ℃, the speed is 2700-3200 m / min, the temperature of the second pair of rollers is 90-100 ℃, the speed is 3700-4300 m / min, the temperature of the third, fourth, fifth pair of rollers is 240-260 ℃, the speed is 5600-6000 m / min, and the sixth pair of rollers is not heated, the speed is 5500-5900 m / min. The parameters of the stretching and setting are as follows: the total draw ratio is 2.0-3.0; the total relaxation rate is 2.0-5.0%, and the winding speed is 5000-6000 m / min to obtain the industrial polyester filament prepared from the industrial tail gas coal-based polyester chip.

[0102] The industrial polyester filament prepared from the industrial tail gas coal-based polyester chip has a fineness of 1100-3300 dtex.

[0103] The breaking strength of the industrial polyester filament prepared from the industrial tail gas coal-based polyester chip is greater than or equal to 7.15 cN / dtex.

[0104] The breaking strength variation coefficient of the industrial polyester filament prepared from the industrial tail gas coal-based polyester chip is less than or equal to 3.0%.

[0105] The breaking elongation of the industrial polyester filament prepared from the industrial tail gas coal-based polyester chip is 11.5-15.5%.

[0106] The intermediate elongation of the terylene industrial filament prepared from the coal-based polyester chip prepared from the industrial tail gas is 5-7%.

[0107] When used for preparing terylene industrial filament for sewing thread, the steps are specifically as follows:

[0108] Step 1, adding PTA, industrial tail gas EG, catalyst preparation liquid, 1-5 ppm acetic acid inhibitor into the slurry preparation system, and preparing the slurry with the molar ratio of EG:PTA being 1.0-1.3 under the stirring action, wherein the content of antimony in the catalyst preparation liquid is 150-180 ppm; then feeding the prepared slurry into the esterification reactor through a slurry conveying pump, and obtaining the esterification initial product under the pressure of 0.06-0.1 MPa and the temperature of 253-273℃; then feeding the esterification initial product into the pre-polycondensation reactor through the pressure difference, and obtaining the polyester prepolymer by pre-polycondensation reaction under the vacuum degree of 8-11 KPa and the temperature of 260-280℃; then feeding the prepolymer into the final polycondensation reactor through the prepolymer conveying pump, and obtaining the polyester melt by final polycondensation reaction under the vacuum degree of 150-250 Pa and the temperature of 272-293℃; finally, cooling and granulating the polyester melt to obtain the 0.6-0.8 dL / g PET polyester chip.

[0109] Step 2, placing the prepared 0.6-0.8 dL / g PET polyester chip into the reaction kettle of the batch polymerization reactor, and stirring under the condition of the vacuum degree being less than or equal to 20 Pa; uniformly heating the temperature in the reaction kettle to 90-120℃ through the heating of the heat conduction oil pipe, and heating for 2-10 h; then continuously heating to 130-180℃, and heating for 5-17 h to obtain the pre-crystallized chip; then continuously heating the temperature in the reaction kettle to 200-240℃ through the heating of the heat conduction oil pipe, and heating for 27-33 h, so that the viscosity of the polyester chip is increased from 0.6-0.8 dl / g to 1.00-1.2 dL / g after solid-phase polymerization, and the moisture of the final high-viscosity chip is less than or equal to 15 ppm.

[0110] Step 3, feeding the high-viscosity chip after solid-phase polymerization into the 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 length-diameter ratio is 24-33, the screw outlet temperature is greater than or equal to 280℃, and the length ratio of the feeding section, the melting section and the metering section in the screw extruder is 1:(1.0-3.0):(1.0-4.0), the feeding section temperature is 290-310℃, the melting section temperature is 300-310℃, and the metering section temperature is 280-295℃.

[0111] Step 4, the extruded melt is distributed to the melt pipe of each spinning beam 2 through the melt manifold 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 sprayed 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 length of the micro-pore channel of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; the filter screen precision of the filter screen in the spinning assembly 1 is 5-30 μm to improve the uniformity of the yarn body. The temperature of the biphenyl is 295-305 ℃ to maintain good melt fluidity and pressure.

[0112] Step 5, after the slow cooling treatment of the melt stream, the melt stream is cooled in the form of side blowing to obtain a yarn body. The temperature of the side blowing is 18-25 ℃, the wind speed is 0.4-0.6 m / s, and the humidity is 50-70%. The heating cover 3 with a temperature of 300-330 ℃ and the heat insulation cylinder 5 with a height of 100-300 mm are used in the slow cooling treatment.

[0113] Step 6, after the yarn body is cooled, the yarn body is stretched, set and wound in the spinning duct to obtain the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip, specifically, the yarn body is oiled, then stretched, set and wound; the stretching and setting are completed by five pairs of rollers; the temperature of the first pair of rollers is 80-95 ℃, the speed is 350-550 m / min, the temperature of the second pair of rollers is 100-125 ℃, the speed is 350-550 m / min, the temperature of the third pair of rollers is 100-125 ℃, the speed is 1400-1550 m / min, the temperature of the fourth pair of rollers is 230-255 ℃, the speed is 2400-2700 m / min, and the fifth pair of rollers is not heated, the speed is 2300-2500 m / min; the parameters of the stretching and setting are as follows: the total stretching multiple is 5-6.2; the total relaxation rate is 3-8%, and the winding speed is 2000-4000 m / min to obtain the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip.

[0114] The fineness of the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip is 100-1110 dtex.

[0115] The breaking strength of the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip is greater than or equal to 7.5 cN / dtex.

[0116] The breaking strength variation coefficient of the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip is less than or equal to 4.0%.

[0117] The breaking elongation of the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip is 13-19%.

[0118] When used for preparing airbag polyester industrial filaments, the steps are as follows:

[0119] Step 1, add PTA, industrial tail gas for EG, catalyst preparation solution, 1-5 ppm acetic acid inhibitor into the slurry preparation system, and under the action of stirring, prepare a slurry with a molar ratio of EG:PTA of 1.0-1.3, wherein the content of antimony in the catalyst preparation solution is 150-180 ppm; then pump the prepared slurry into an esterification reactor through a slurry pump, and under the conditions of a pressure of 0.06-0.1 MPa and a temperature of 253-273℃, stir to obtain an esterification primary product; then transport the esterification primary product to a pre-polycondensation reactor under a pressure difference, and under the conditions of a vacuum degree of 8-11 KPa and a temperature of 260-280℃, carry out pre-polycondensation reaction to obtain a polyester prepolymer; then transport the prepolymer to a final polycondensation reactor under the conditions of a vacuum degree of 150-250 Pa and a temperature of 272-293℃, and carry out final polycondensation reaction to obtain a polyester melt; finally, cool and granulate the polyester melt to obtain 0.6-0.8 dL / g PET polyester chips.

[0120] Step 2, place the prepared 0.6-0.8 dL / g PET polyester chips in the reaction kettle of a batch polymerization reactor, and under the condition of a vacuum degree less than or equal to 20 Pa, stir, uniformly heat the temperature in the reaction kettle to 90-120℃ by heating the heat conduction oil pipe, and heat for 2-10 h, then continue to heat to 130-180℃ and heat for 5-17 h to obtain pre-crystallized chips, then continue to uniformly heat the temperature in the reaction kettle to 200-240℃ by heating the heat conduction oil pipe, and continue to heat for 27-33 h, 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 of the final high-viscosity chips is less than or equal to 15 ppm.

[0121] Step 3, transport the high-viscosity chips after solid-phase polymerization to a screw extruder, and then extrude the melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw length-diameter ratio is 24-33, the screw outlet temperature is ≥280℃, and the length ratio of the feeding section, the melting section, and the metering section in the screw extruder is 1:(1.0-3.0):(1.0-4.0), the feeding section temperature is 290-310℃, the melting section temperature is 300-310℃, and the metering section temperature is 280-295℃.

[0122] Step 4, the extruded melt is distributed to the melt duct of each spinning beam 2 through the melt manifold 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 sprayed from the spinneret 4 to obtain a melt stream. The number of spinneret holes in the spinneret 4 is 72-300; the ratio of the length of the micro-pore channel of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; the filter screen precision of the filter screen in the spinning assembly 1 is 5-30 μm to improve the uniformity of the yarn body. The temperature of the biphenyl is 295-305 ℃ to maintain good melt fluidity and pressure.

[0123] Step 5, after the slow cooling treatment of each group of melt streams, the melt streams are cooled in the form of side blowing to obtain a yarn body. The temperature of the side blowing is 18-25 ℃, the wind speed is 0.4-0.6 m / s, and the humidity is 50-70%. The heating cover 3 has a temperature of 300-330 ℃ and the heat insulation cylinder 5 has a height of 200-400 mm during the slow cooling treatment.

[0124] Step 6, after the yarn body is cooled, the yarn body is stretched, set and wound in the spinning duct to obtain the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip, specifically, the yarn body is oiled, then stretched, set and wound; the stretching and setting are completed by six pairs of rollers; the temperature of the first pair of rollers is 80-95 ℃, the speed is 300-600 m / min, the temperature of the second pair of rollers is 100-135 ℃, the speed is 300-600 m / min, the temperature of the third pair of rollers is 100-135 ℃, the speed is 1400-1600 m / min, the temperature of the fourth pair of rollers is 230-255 ℃, the speed is 2500-2700 m / min, the temperature of the fifth pair of rollers is 230-255 ℃, the speed is 2400-2600 m / min, the sixth pair of rollers is not heated, and the speed is 2000-2600 m / min; the parameters of the stretching and setting are as follows: the total stretching multiple is 5-6.2; the total relaxation rate is 7-9%, and the winding speed is 2000-4000 m / min to form a wound product to obtain the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip.

[0125] The industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip has a fineness of 350-2220 dtex.

[0126] The breaking strength of the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip is greater than or equal to 7.8 cN / dtex.

[0127] The breaking strength variation coefficient of the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip is less than or equal to 3.0%.

[0128] The elongation at break of the terylene industrial filament prepared from the coal-based polyester chip prepared from the industrial off-gas is 18-24%.

[0129] When used for preparing terylene industrial filament for safety belt, the steps are specifically as follows:

[0130] Step 1, adding PTA, industrial off-gas for EG, catalyst preparation liquid, 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, wherein the content of antimony in the catalyst preparation liquid is 150-180 ppm; then feeding the prepared slurry into an esterification reactor through a slurry conveying pump, and stirring under a pressure of 0.06-0.1 MPa and a temperature of 253-273 ℃ to obtain an esterification initial product; then conveying the esterification initial product into a pre-polycondensation reactor under a vacuum degree of 8-11 KPa and a temperature of 260-280 ℃ through pressure difference to carry out pre-polycondensation reaction to obtain a polyester prepolymer; then conveying the prepolymer into a terminal polycondensation reactor under a vacuum degree of 150-250 Pa and a temperature of 272-293 ℃ to carry out terminal polycondensation reaction to obtain a polyester melt; and finally cooling and granulating the polyester melt to obtain 0.6-0.8 dL / g PET polyester chip.

[0131] Step 2, placing the prepared 0.6-0.8 dL / g PET polyester chip into a reaction kettle of a batch polymerization reactor, and stirring under a vacuum degree of less than or equal to 20 Pa, uniformly heating the temperature in the reaction kettle to 90-120 ℃ through a heating conduction oil pipe, and heating for 2-10 h, then continuously heating to 130-180 ℃ and heating for 5-17 h to obtain a pre-crystallized chip, and then continuously uniformly heating the temperature in the reaction kettle to 200-240 ℃ through the heating conduction oil pipe, and continuously heating for 27-33 h to make the viscosity of the polyester chip increase from 0.6-0.8 dl / g to 1.00-1.2 dL / g after solid-phase polymerization, and the moisture of the final high-viscosity chip is less than or equal to 15 ppm.

[0132] Step 3, conveying the high-viscosity chip after solid-phase polymerization to a screw extruder, and then extruding a melt through the screw extruder, wherein the screw diameter of the screw extruder is 75-170 mm, the screw length-diameter ratio is 24-33, the screw outlet temperature is ≥280 ℃, and the length ratio of the feeding section, the melting section and the metering section in the screw extruder is 1:(1.0-3.0):(1.0-4.0), the feeding section temperature is 290-310 ℃, the melting section temperature is 300-310 ℃, and the metering section temperature is 280-295 ℃.

[0133] Step 4, the extruded melt is distributed to the melt duct of each spinning beam 2 through the melt manifold 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 sprayed 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 length of the micro-pore channel of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; the filter screen precision of the filter screen in the spinning assembly 1 is 5-30 μm to improve the uniformity of the yarn body. The temperature of the biphenyl is 295-305 ℃ to maintain good melt fluidity and pressure.

[0134] Step 5, after the slow cooling treatment of each group of melt streams, the melt streams are cooled in the form of side blowing to obtain a yarn body. The temperature of the side blowing is 18-25 ℃, the wind speed is 0.4-0.6 m / s, and the humidity is 50-70%. The heating cover 3 has a temperature of 300-330 ℃ and the heat insulation cylinder 5 has a height of 300-500 mm during the slow cooling treatment.

[0135] Step 6, after the yarn body is cooled, the yarn body is stretched, set and wound in the spinning duct to obtain the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip, specifically, the yarn body is oiled, then stretched, set and wound; the stretching and setting are completed by five pairs of rollers; the temperature of the first pair of rollers is 85-100 ℃, the speed is 300-500 m / min, the temperature of the second pair of rollers is 110-140 ℃, the speed is 300-500 m / min, the temperature of the third pair of rollers is 100-140 ℃, the speed is 1200-1500 m / min, the temperature of the fourth pair of rollers is 220-250 ℃, 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 the stretching and setting are as follows: the total stretching multiple is 5-6.5; the total relaxation rate is 1-5%, and the winding speed is 2000-4000 m / min to form the industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip.

[0136] The industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip has a fineness of 555-2220 dtex.

[0137] The industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip has a breaking strength greater than or equal to 7.9 cN / dtex.

[0138] The industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip has a breaking strength variation coefficient less than or equal to 3.0%.

[0139] The industrial polyester industrial filament prepared from the industrial tail gas coal-based polyester chip has an elongation at break of 11.5-16.5%.

[0140] The intermediate elongation of the polyester industrial filament prepared from the coal-based polyester chip made from the industrial off-gas is 5-7%.

[0141] Example 1

[0142] The polyester industrial filament for tire cord is a high modulus and low shrinkage filament, and the preparation steps of the polyester industrial filament used are as follows:

[0143] Step 1, add PTA, EG made from industrial off-gas, catalyst preparation solution, 2.5 ppm acetic acid inhibitor into the slurry preparation system, and under the action of stirring, a slurry with a molar ratio of EG:PTA of 1.06 is prepared, wherein the catalyst antimony content is 180 ppm; then the prepared slurry is pumped into the esterification reactor through the slurry conveying pump, and under the conditions of a pressure of 0.06-0.08 MPa and a temperature of 258-273℃, stirring is carried out to obtain an esterification primary product; then the esterification primary product is transported to a pre-polycondensation reactor under a vacuum degree of 9.5 KPa and a temperature of 269-277℃ through pressure difference to carry out pre-polycondensation reaction to obtain a polyester prepolymer; then the prepolymer is transported to a terminal polycondensation reactor under a vacuum degree of 200 Pa and a temperature of 274-293℃ to carry out terminal polycondensation reaction to obtain a polyester melt; finally, the polyester melt is cooled and granulated to obtain 0.67 dL / g PET polyester chip.

[0144] Step 2, place the industrial off-gas coal-based polyester chip with a viscosity of 0.67 dl / g into a batch-type drum reactor, i.e., into a batch-type solid-phase polymerization reactor, and rotate under a vacuum degree of 10 Pa; then uniformly heat the temperature in the reactor to 100℃ through a heating conduction oil pipe and heat for 3 h, then continue to heat to 160℃ and heat for 6 h to obtain a pre-crystallized piece; then continue to uniformly heat the temperature in the reactor to 223℃ through a heating conduction oil pipe and continue to heat for 30 h, so that the viscosity of the polyester chip is increased from 0.67 dl / g to 1.13 dL / g after solid-phase polymerization, and a high-viscosity chip is formed.

[0145] Step 3, transport the high-viscosity chip after solid-phase polymerization to a screw extruder, and then extrude the melt through the screw extruder, wherein the screw diameter of the screw extruder is 130 mm, and the length and temperature of the feeding 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.

[0146] Step 4, the extruded melt is distributed to the melt ducts of each spinning beam 2 through the melt manifold 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 sprayed 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 length of the micro-pore channel of the spinneret hole to the diameter of the spinneret hole is 1.3, the length of the micro-pore channel refers to the length of the spinneret hole in the direction of the melt flow; the maximum precision of the filter screen in the spinning assembly 1 is 25 μm, which refers to the maximum precision of the four layers of metal filter screen, so as to improve the uniformity of the yarn body. The temperature of the biphenyl is 298℃, so as to maintain good melt fluidity and pressure.

[0147] Step 5, after the slow cooling treatment of each group of melt streams, the melt streams are cooled through the form of circular blowing to obtain the yarn body. The temperature of the circular blowing is 60℃, 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℃, and the height of the heat insulation cylinder 5 is 80 mm, so as to improve the phenomenon of large CV value of physical properties, many broken ends and the like caused by uneven cooling.

[0148] Step 6, after the yarn body is cooled, the yarn body is stretched, shaped and wound in the spinning duct to obtain the polyester industrial filament prepared from the industrial tail gas coal-based polyester chip, specifically, the yarn body is oiled, then stretched, shaped and wound; wherein the stretching and shaping is completed through six pairs of rollers; the temperature of the first pair of rollers is 90℃, the speed is 2911 m / min, the temperature of the second pair of rollers is 95℃, the speed is 4075 m / min, the temperature of the third, fourth, fifth pair of rollers is 247℃, the speed is 5821 m / min, and the temperature of the sixth pair of rollers is not heated, the speed is 5600 m / min; the parameters of the stretching and shaping are: the total stretching multiple is 2.0; the total relaxation rate is 3.95%, and the winding speed is 5600 m / min to form the polyester industrial filament prepared from the industrial tail gas coal-based polyester chip.

[0149] Example 2

[0150] Preparation steps of the polyester industrial filament for sewing thread:

[0151] Step 1, add PTA, industrial tail gas for EG, catalyst preparation solution, 2.5ppm acetic acid inhibitor into the slurry preparation system, under the action of stirring, prepare the slurry with the molar ratio of EG:PTA at 1.06, wherein the catalyst antimony content is 180ppm; then pump the prepared slurry into the esterification reactor through the slurry pump, under the pressure of 0.06-0.08MPa and the temperature of 258-273℃, stir to obtain the esterification initial product; then transport the esterification initial product to the pre-polycondensation reactor under the pressure of 9.5KPa and the temperature of 269-277℃ through the pressure difference to carry out the pre-polycondensation reaction to obtain the polyester prepolymer; then transport the prepolymer to the final polycondensation reactor under the condition of the vacuum degree of 200Pa and the temperature of 274-293℃ through the prepolymer pump to carry out the final polycondensation reaction to obtain the polyester melt; finally, the polyester melt is cooled and granulated to obtain 0.67dL / g PET polyester chip.

[0152] Step 2, place the industrial tail gas coal-based polyester chip with the viscosity of 0.67dl / g into the intermittent drum reaction kettle, i.e. into the intermittent solid-phase polymerization reaction kettle, under the condition of the vacuum degree of 10pa, rotate, then uniformly heat the temperature in the reaction kettle to 100℃ through the heating conduction oil pipe and heat for 3h, continue to heat to 160℃ and heat for 6h to obtain the pre-crystallized chip, then uniformly heat the temperature in the reaction kettle to 220℃ through the heating conduction oil pipe and continue to heat for 29h, so that the viscosity of the polyester chip is increased from 0.67dl / g to 1.12dL / g after the solid-phase polymerization, and the high-viscosity chip is formed.

[0153] Step 3, transport the high-viscosity chip after the solid-phase polymerization to the screw extruder, then extrude the melt through the screw extruder, wherein the screw diameter of the screw extruder is 125mm, the length and temperature of the feeding 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.

[0154] Step 4, the extruded melt is distributed to the melt pipe of each spinning beam 2 through the melt manifold to form the spinning melt, the spinning melt enters the spinning assembly 1 through the metering pump, is filtered through the filter screen in the spinning assembly 1, is extruded from the spinneret 4 to obtain the melt stream. The number of the spinneret holes in the spinneret 4 is shown in Table 2; the ratio of the micro-pore channel length of the spinneret hole to the diameter of the spinneret hole is 2.0, the micro-pore channel length refers to the length of the spinneret hole in the direction of the melt advancement; the maximum precision of the filter screen in the spinning assembly 1 is 20μm to improve the uniformity of the yarn body. The temperature of the biphenyl is 296℃ to maintain good melt fluidity and pressure.

[0155] Step 5, after the slow cooling treatment of each group of melt streams, the melt streams are cooled by side blowing to obtain the yarn body. The side blowing temperature is 25°C, the wind speed is 0.5 m / 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 heat insulation cylinder 5 is 150 mm, so as to improve the phenomenon of large CV value of physical properties and many broken ends due to uneven cooling.

[0156] Step 6, after the above cooled yarn body enters the spinning duct, the yarn body is stretched, shaped and wound to obtain the industrial polyester filament prepared from the industrial tail gas coal-based polyester chip. Specifically, the yarn body is oiled, then stretched, shaped and wound. The stretching and shaping are completed by five pairs of rollers. The temperature of the first pair of rollers is 85°C, the speed is 449 m / min, the temperature of the second pair of rollers is 115°C, the speed is 456 m / min, the temperature of the third pair of rollers is 115°C, the speed is 1464 m / min, the temperature of the fourth pair of rollers is 240°C, the speed is 2540 m / min, and the fifth pair of rollers is not heated, the speed is 2410 m / min. The total stretching multiple is 5.66, and the total relaxation rate is 5.83%. The yarn is wound at a speed of 2400 m / min to form the industrial polyester filament prepared from the industrial tail gas coal-based polyester chip.

[0157] Example 3

[0158] Preparation steps of the airbag polyester industrial filament:

[0159] Step 1, in the slurry preparation system, PTA, industrial tail gas EG, catalyst preparation liquid and 2.5 ppm acetic acid inhibitor are added, and under the action of stirring, a slurry with a EG:PTA molar ratio of 1.06 is prepared, wherein the catalyst antimony content is 180 ppm. Then the prepared slurry is pumped into an esterification reactor by a slurry pump, and under the conditions of a pressure of 0.06-0.08 MPa and a temperature of 258-273°C, stirring is carried out to obtain an esterification primary product. Then the esterification primary product is transported to a pre-polycondensation reactor with a vacuum degree of 9.5 KPa and a temperature of 269-277°C by pressure difference to carry out pre-polycondensation reaction to obtain a polyester prepolymer. Then the prepolymer is transported to a terminal polycondensation reactor under the conditions of a vacuum degree of 200 Pa and a temperature of 274-293°C to carry out terminal polycondensation reaction to obtain a polyester melt. Finally, the polyester melt is cooled and granulated to obtain 0.67 dL / g PET polyester chip.

[0160] Step 2, the industrial tail gas coal-based polyester chip with viscosity of 0.67 dl / g is placed in a batch drum reaction kettle, i.e. in a batch solid phase polymerization reaction kettle, and rotated under the condition of vacuum degree of 10 pa, and then the temperature in the reaction kettle is uniformly raised to 100 ℃ by heating the heat conducting oil pipe, and heated for 3 h, then continuously raised to 160 ℃ and heated for 6 h to obtain pre-crystallized chips, and then the temperature in the reaction kettle is uniformly raised to 220 ℃ by heating the heat conducting oil pipe, and continuously heated for 29 h, so that the viscosity of the polyester chip is increased from 0.67 dl / g to 1.12 dL / g after solid phase polymerization, and high viscosity chip is formed.

[0161] Step 3, the high viscosity chip after solid phase polymerization is transported to a screw extruder, and then the melt is extruded by the screw extruder, wherein the screw diameter of the screw extruder is 130 mm, the length and temperature of the feeding 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.

[0162] Step 4, the extruded melt is distributed to the melt pipe of each spinning beam 2 through the melt manifold to form a spinning melt, the spinning melt enters the spinning assembly 1 through the metering pump, and is filtered by the filter screen in the spinning assembly 1, the melt is extruded 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 length of the micro-pore channel of the spinneret hole to the diameter of the spinneret hole is 2.0, the length of the micro-pore channel refers to the length of the spinneret hole in the direction of the melt advancing; the maximum precision of the filter screen in the spinning assembly 1 is 20 μm to improve the uniformity of the yarn body. The temperature of the biphenyl is 296 ℃ to maintain good melt fluidity and pressure.

[0163] Step 5, after the slow cooling treatment of each group of melt streams, the melt streams are cooled by side blowing to obtain a yarn body. The side blowing temperature is 25 ℃, the wind speed is 0.55 m / s, and the humidity is 60%. The temperature of the heating cover 3 in the slow cooling device is 330 ℃, and the height of the heat insulation cylinder 5 is 250 mm, to improve the phenomenon of large CV value of physical properties and many broken ends due to uneven cooling.

[0164] Step 6, after the above cooled filament body enters the spinning duct, the stretching setting and winding treatment are carried out, and the industrial polyester filament prepared from the industrial tail gas coal-based polyester chip is obtained. Specifically, the surface of the filament body is oiled, and then stretched, set and wound; wherein the stretching setting is completed by six pairs of rollers; the temperature of the first pair of rollers is 85℃, the speed is 441m / min, the temperature of the second pair of rollers is 120℃, the speed is 542m / min, the temperature of the third pair of rollers is 120℃, the speed is 1764m / min, the temperature of the fourth pair of rollers is 237℃, the speed is 2603m / min, the temperature of the fifth pair of rollers is 237℃, the speed is 2500m / min, and the sixth pair of rollers is not heated, the speed is 2400m / min; wherein the parameters of the stretching setting are: the total stretching multiple is 5.9; the total relaxation rate is 8.46%, and the winding is carried out at a winding speed of 2400m / min to form the industrial polyester filament prepared from the industrial tail gas coal-based polyester chip.

[0165] Example 4

[0166] Preparation steps of the polyester industrial filament for safety belt:

[0167] Step 1, in the slurry preparation system, PTA, industrial tail gas EG, catalyst preparation liquid and 2.5ppm acetic acid inhibitor are added, and under the action of stirring, a slurry with a molar ratio of EG:PTA of 1.06 is prepared, wherein the content of catalyst antimony is 180ppm; then the prepared slurry is pumped into the esterification reactor by a slurry pump, and under the conditions of a pressure of 0.06-0.08MPa and a temperature of 258-273℃, stirring is carried out to obtain an esterification primary product; then the esterification primary product is transported to a pre-polycondensation reactor under a pressure difference, and pre-polycondensation reaction is carried out under the conditions of a vacuum degree of 9.5KPa and a temperature of 269-277℃ to obtain a polyester prepolymer; then the prepolymer is transported to a final polycondensation reactor under the conditions of a vacuum degree of 200Pa and a temperature of 274-293℃ to carry out final polycondensation reaction and obtain a polyester melt; finally, the polyester melt is cooled and granulated to obtain 0.67dL / g PET polyester chip.

[0168] Step 2, the industrial tail gas coal-based polyester chip with a viscosity of 0.67dl / g is placed in a batch-type drum reaction kettle, i.e. in a batch-type solid-phase polymerization reaction kettle, and rotated under a vacuum degree of 10pa; then the temperature in the reaction kettle is uniformly raised to 100℃ by heating the heat conduction oil pipe, and heated for 3h; then the temperature in the reaction kettle is uniformly raised to 160℃ by heating the heat conduction oil pipe, and heated for 6h to obtain pre-crystallized chips; then the temperature in the reaction kettle is uniformly raised to 223℃ by heating the heat conduction oil pipe, and heated for 30h, so that the viscosity of the polyester chip is increased from 0.67dl / g to 1.13dL / g after solid-phase polymerization, and high-viscosity chips are formed.

[0169] Step 3, the high-viscosity cut piece after solid-phase polymerization is 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, the length and temperature of the feeding section, the length and temperature of the melting section, the length and temperature of the metering section, and the temperature of the screw outlet are shown in Table 1.

[0170] Step 4, the extruded melt is distributed to the melt pipe of each spinning beam 2 through the melt manifold 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 sprayed 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 length of the micro-pore channel of the spinneret hole to the diameter of the spinneret hole is 2.0, the length of the micro-pore channel refers to the length of the spinneret hole in the direction of the melt advancement; the maximum precision of the filter screen in the spinning assembly 1 is 25 μm to improve the uniformity of the yarn body. The temperature of the biphenyl is 296 ℃ to maintain good melt fluidity and pressure.

[0171] Step 5, after the slow cooling treatment of each group of melt streams, the melt streams are cooled in the form of side blowing to obtain a yarn body. The temperature of the side blowing is 25 ℃, the wind speed is 0.55 m / s, and the humidity is 60%. The temperature of the heating cover 3 in the slow cooling device is 310 ℃, and the height of the heat insulation cylinder 5 is 450 mm to improve the phenomenon of large CV value of physical properties and many broken ends due to uneven cooling.

[0172] Step 6, after the yarn body is cooled, the yarn body is stretched, shaped, and wound in the spinning duct to obtain the polyester industrial filament prepared from the coal-based polyester chip of industrial tail gas, specifically, the yarn body is oiled, then 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 ℃, the drawing speed is 403 m / min, the temperature of the second pair of rollers is 120 ℃, the drawing speed is 413 m / min, the temperature of the third pair of rollers is 120 ℃, the drawing speed is 1314 m / min, the temperature of the fourth pair of rollers is 230 ℃, the drawing speed is 2457 m / min, and the fifth pair of rollers is not heated, and the drawing speed is 2400 m / min; wherein the parameters of the stretching and shaping are: the total drawing multiple is 6.09; the total relaxation rate is 2.34%, and the winding speed is 2400 m / min to form a wound product, thereby obtaining the polyester industrial filament prepared from the coal-based polyester chip of industrial tail gas.

[0173] Comparative Examples 1-4

[0174] The coal-based chip in Examples 1-4 is replaced by 0.67 dl / g petroleum-based PET chip, and the polyester industrial filament for producing different products is produced by the petroleum-based chip according to the method of Examples 1-4. The relevant parameters in the steps are shown in Tables 1-4.

[0175] In Examples 1-4 and Comparative Examples 1-4, the filter screen in the spinning assembly 1 uses four layers of metal filter screens, which have good high-temperature oxidation resistance, melt scouring and corrosion resistance, and good structural stability; and the filtration precision is gradually reduced layer by layer, which can remove impurities and gel particles that may be present in the coal-based chip melt, prevent the spinning orifice of the spinning assembly 1 from being blocked, and establish a stable spinning pressure, which is conducive to uniformly distributing the melt to all the spinning orifices on the spinning plate and making the melt have the same flow path, flow rate and pressure. For example, from top to bottom, the first layer of metal filter screen has a precision of 20 μm or 25 μm, the second layer of metal filter screen has a precision of 15 μm, the third layer of metal filter screen has a precision of 10 μm, and the fourth layer of metal filter screen has a precision of 5 μm. The four layers of metal filter screens are pressed into an integrated structure.

[0176] Table 1: Screw extruder related parameters

[0177] Table 2: Spinning related parameters I

[0178] Table 3: Spinning related parameters II

[0179] Table 4: Stretching related parameters

[0180] The related performance parameters of the polyester industrial filaments obtained in Examples 1-4 and Comparative Examples 1-4 are shown in Tables 5-7.

[0181] Table 5: Related performance parameters of polyester industrial filaments

[0182] Table 6: Related performance parameters of polyester industrial filaments

[0183] Table 7: Related performance parameters of polyester industrial filaments

[0184] 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 rate are determined according to GB / T 16604 standard. The oil content is determined according to GB / T6504-NMR standard. The network degree is determined according to the crochet method.

[0185] The related performance parameters of the petroleum-based chips used in Comparative Examples 1-4 are shown in Table 8 below, and the related performance parameters of the coal-based chips used in Example 3 are also shown in Table 8 below.

[0186] Table 8 Performance comparison of petroleum-based chips and tail gas coal-based chips

[0187] The L value and the B value are determined by Lab color analysis.

[0188] Comparative Example 5

[0189] Adjusting the esterification reaction temperature, the polycondensation reaction temperature, the amount of catalyst, and the use of inhibitors will affect the performance of the chips, as shown in Table 9.

[0190] Table 9 Performance parameters of industrial tail gas coal-based chips prepared by different polyester reaction process conditions

[0191] The viscosity and DEG are determined according to GB / T 14190 standard, and the terminal carboxyl group is determined by a potentiometric titrator.

[0192] As can be seen from the data in Table 9, after adding the inhibitor, the other performance of the chips does not change much, but the diethylene glycol (DEG) content decreases significantly. The content of DEG in the polyester is essentially the content of its ether bond. The presence of ether bonds to some extent destroys the regularity of the orderly arrangement of macromolecules, making it difficult to crystallize, and the corresponding fiber strength decreases and the dry heat shrinkage increases. Moreover, the ether bond in diethylene glycol can change the ethylene glycol segment in the polyester macromolecule, thereby increasing the ether bond in the macromolecule. Since the ether bond is a dye-philic group, it will affect the dyeing performance of the polyester fiber.

[0193] Comparative Example 6

[0194] Comparative Example 6 differs from Example 4 only in that the four-layer metal filter screen is replaced by a three-layer filter structure commonly used for petroleum-based chips, with a felt screen in the middle and supported by sieve plates on the top and bottom, and the filter precision is 20 μm.

[0195] Comparative Example 7

[0196] Comparative Example 7 differs from Example 4 only in that the length ratio of the feeding section, the melting section, and the metering section is 1:1:1, and the length of each section is 864 mm.

[0197] The polyester industrial filaments prepared in Comparative Examples 6 and 7 were tested, and the results are shown in Table 10. The number of broken ends and the amount of lint during the preparation of the polyester industrial filaments in Comparative Examples 6 and 7, Comparative Example 7, Example 4, and Comparative Example 4 are shown in Table 11.

[0198] Table 10 Test results of the polyester industrial filaments prepared in Comparative Examples 6 and 7

[0199] Table 11 Breakage frequency and lint amount detection data of Comparative Example 6, Comparative Example 7, Example 4 and Comparative Example 4

[0200] In summary, Comparative Example 6 uses a felt screen structure, and during the process of preparing polyester industrial filaments from coal-based chips, there are relatively many impurities, which causes the filter structure to be blocked and the spinning assembly 1 to rise quickly. As the assembly pressure rises, the efficiency of the metering pump decreases, the fineness decreases, the melt degrades severely, the strength and elongation decrease, and the lint and breakage increase significantly.

[0201] Since the by-product of the waste industrial tail gas to ethylene glycol is oxalic acid, which remains in ethylene glycol, the boiling point of oxalic acid is 150°C, which cannot be removed in the process column. Oxalic acid at the bottom of the process column will be discharged together with the ethylene glycol product into the polymerization section production system, and during the polymerization process, the phenomenon of increasing flexible chains will occur, which will cause the thermal stability of the polyester product to decrease. Therefore, high screw temperature will cause a large amount of degradation, but under the condition of low temperature and no increase in the length of the metering section, the melt flowability is poor and the mixture is not uniform, the spinnability is poor, and the uniformity of stretching is affected. Therefore, the fineness of Comparative Example 7 decreases, the fineness CV increases, the strength and elongation decrease, the strength CV increases, and the lint and breakage increase significantly.

[0202] The present application controls the carboxyl content, intrinsic viscosity, and tackiness of coal-based chips, appropriately lengthens the melting section or the metering section to extend the residence time, and sets multiple layers of metal screens, so that the performance parameters of the polyester industrial filaments prepared from coal-based chips are closer to those of the polyester industrial filaments prepared from petroleum-based chips.

[0203] The above examples are only used to illustrate the technical solutions of the present application and are not limited. The present application has been described in detail with reference to the preferred embodiments. Those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the spirit and scope of the technical solutions of the present application, and all should be included in the scope of the claims of the present application. Industrial applicability

[0204] The application selects industrial tail gas to produce ethylene glycol as raw material, and adjusts the slurry of EG: PTA molar ratio of 1.0-1.3, uses catalyst containing antimony and acetic acid series inhibitor, synthesizes coal-based PET chip with intrinsic viscosity of 0.6-0.8 dl / g, carboxyl end group content of 25-30 mol / t, after tackifying, coal-based high tack chip of 1.00-1.2 dl / g is obtained, and then spinning is carried out on an industrial yarn production line; the screw temperature is controlled, the length of the feeding section and the metering section is adjusted, the chip is fully melted while ensuring that the melt does not further produce chain scission phenomenon due to the occurrence of thermal degradation because of containing a small amount of flexible chain, and the stability of the screw outlet pressure is ensured; a filter is arranged in the spinning assembly to improve the problem that the spinning assembly pressure rises quickly due to the high impurity content of the coal-based chip; the stretching and setting conditions are optimized and adjusted, so that the physical properties, hairiness and spinnability can all meet the requirements.

[0205] In addition, the polyester chip produced by the method and the polyester industrial filament prepared by the method can be applied to various industrial applications. For example, the polyester chip produced by the method and the polyester industrial filament prepared by the method can be applied to the field of chemical fibers.

Claims

1. A method for producing polyester chips and preparing polyester industrial filaments by using industrial tail gas to produce ethylene glycol, characterized in that, Comprising the following steps: Step 1, adding terephthalic acid (PTA), industrial tail gas made of ethylene glycol (EG), catalyst preparation solution, 1-5 ppm acetic acid inhibitor in the slurry preparation system, and preparing the slurry with the molar ratio of EG:PTA being 1.0-1.3 under the action of 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 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 the reaction kettle of a batch polymerization reactor to obtain 1.00-1.2 dL / g PET polyester chips; Step 3, conveying the 1.00-1.2 dL / g PET polyester chips to a screw extruder to extrude a melt through the screw extruder; Step 4, the melt extruded by the screw extruder is distributed to a spinning beam to form a spinning melt, which is filtered and then sprayed from a spinneret under the condition of 295-305 ℃ to obtain a melt flow; Step 5, performing slow cooling treatment on the melt flow, and then cooling the melt flow by ring blowing or side blowing to obtain a yarn body; Step 6, the cooled yarn body enters a spinning duct to perform drawing setting and winding treatment to obtain a coal-based polyester chip prepared polyester industrial filament.

2. The method of claim 1, wherein, The catalyst preparation solution is a catalyst with an antimony content of 150-180 ppm; And / or, the pressure of the esterification reactor is set to 0.06-0.1 Mpa, and the temperature is set to 253-273 ℃; And / or, the vacuum degree of the pre-polycondensation reaction is 8-11 Kpa, and the temperature is 260-280 ℃; And / or, the vacuum degree of the final polycondensation reaction is 150-250 Pa, and the temperature is 272-293 ℃.

3. The method according to claim 1 or 2, characterized in that, The esterification reactor comprises a first esterification kettle and a second esterification kettle, wherein the temperature of the first esterification kettle is set to 258-262 ℃; and the temperature of the second esterification kettle is set to 262-276 ℃.

4. The method according to any one of claims 1 to 3, characterized in that, The reaction kettle of the batch polymerization reactor is stirred under the condition that the vacuum degree is less than or equal to 20 Pa, the temperature in the reaction kettle is uniformly raised to 90-120 ℃ by heating the heat conducting oil pipe for 2-10 h, then continuously raised to 130-180 ℃ for 5-17 h to obtain a pre-crystallized sheet, and then uniformly raised to 200-240 ℃ for 27-33 h, so that the viscosity of the polyester chip is increased from 0.6-0.8 dl / g to 1.00-1.2 dL / g after solid phase polymerization, and the moisture of the final high-viscosity chip is less than or equal to 15 ppm.

5. The method according to any one of claims 1 to 4, characterized in that, The screw outlet temperature of the screw extruder is ≥280℃; and / or, the length ratio of the feeding 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 feeding 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 feeding section, melting section and metering section of the screw extruder is 1:(1.8-2.2):(2.8-4).

6. The method according to any one of claims 1 to 5, characterized in that, The screw diameter of the screw extruder is 75-170mm, and the screw length-diameter ratio is 24-33.

7. The method according to any one of claims 1 to 6, characterized in that, The filtration adopts a multi-layer metal filter screen, the filtration precision of which decreases layer by layer along the running direction of the spinning melt, and the spinning melt is uniformly distributed into the spinneret holes.

8. The method of claim 7, wherein, The ratio of the micro-pore channel length of the spinneret hole to the diameter of the spinneret hole is 1.0-3.0; and / or, the filtration precision is 5-30μm; preferably, the filtration precision is 20-30μm.

9. The method according to any one of claims 1 to 8, characterized in that, The slow cooling treatment is completed by a heating cover with a temperature of 300-330℃ and a heat insulation cylinder with a height of 50-500mm; the ring blowing temperature is 50-70℃, the dynamic pressure is 0.02-0.06kPa, and the humidity is 50-70%; the side blowing temperature is 18-25℃, the wind speed is 0.4-0.6m / s, and the humidity is 50-70%.

10. The method according to any one of claims 1 to 9, characterized in that, The parameters of the drawing setting include: the drawing speed is 300-4000m / min; the total drawing multiple is 2.0-6.5; the setting temperature is 230-260℃; the total relaxation rate is 1.6-9%; and the winding speed is 2000-7000m / min.

11. The method according to any one of claims 1 to 10, characterized in that, The end carboxyl group content of the polyester chip made from industrial tail gas is 25-30mol / t; and / or, the color value L of the polyester chip made from industrial tail gas is ≥79; and / or, the color value b of the polyester chip made from industrial tail gas is 1.5±2.0; and / or, the moisture content of the polyester chip made from industrial tail gas is ≤0.40%; and / or, the diethylene glycol content of the polyester chip made from industrial tail gas is 0.80-1.00%.

12. The method according to any one of claims 1 to 11, characterized in that, The fineness of the polyester industrial filament is 100-3300dtex, preferably, the fineness of the polyester industrial filament is 167-3300dtex; and / or, the breaking strength of the polyester industrial filament is ≥7.15cN / dtex; and / or, the breaking strength variation coefficient of the polyester industrial filament is ≤4.0%; and / or, the breaking elongation of the polyester industrial filament is 11.5-24%; and / or, the intermediate elongation of the polyester industrial filament is 5-10%.

13. The method according to any one of claims 1 to 12, characterized in that, The ethylene glycol content of the ethylene glycol made from industrial tail gas is greater than or equal to 99%.

14. The method according to any one of claims 1 to 12, characterized in that, The ethylene glycol content of the ethylene glycol made from industrial tail gas is greater than or equal to 99.9%.

15. A polyester industrial filament prepared based on the method of any one of claims 1 to 14.

16. The polyester industrial filament according to claim 15, characterized in that, The polyester industrial filament is used for preparing tire cord, safety belt, air bag or sewing thread.

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