CN110760058A - Production process and application method of cationic polyester melt - Google Patents

Abstract

The invention relates to the fiber processing field of melt direct spinning cation polyester filament and short fiber, in particular to the chemical synthesis technical field of processes of synthesizing polyester third monomer ethylene glycol isophthalate-5-sodium sulfonate by a direct esterification method, esterification synthesis, polycondensation synthesis and the like. The invention relates to a production process of a cationic polyester melt, which comprises the following steps: (1) to obtain esterified ester sodium ethylene glycol isophthalate-5-sulfonate; (2) obtaining esterified ethylene terephthalate; the preparation method comprises the following steps of (1), (3) obtaining a mixed esterification product, (4) completing a pre-polycondensation reaction by enabling the mixed esterification product obtained in the step (3) to reach a certain intrinsic viscosity to obtain a pre-polycondensation reaction product, and (5) enabling the pre-polycondensation reaction product to enter a final polycondensation reaction kettle, completing the final polycondensation reaction by enabling the intrinsic viscosity of a polymer under the action of further improving the reaction temperature and the vacuum degree, and obtaining a polyester melt meeting the requirements of production of melt direct spinning cationic polyester filaments and short fibers.

Description

Production process and application method of cationic polyester melt

Technical Field

The invention relates to the fiber processing field of melt direct spinning cation polyester filament and short fiber, in particular to the chemical synthesis technical field of processes of synthesizing polyester third monomer ethylene glycol isophthalate-5-sodium Sulfonate (SIPEG) by a direct esterification method, esterification synthesis, polycondensation synthesis and the like.

Background

Since the advent of the cationic polyester fiber, the cationic polyester fiber is widely used in the fields of textile clothing and home textiles due to the excellent dyeing property of the cationic polyester fiber, and the polyester fiber overcomes the difficulties that the polyester fiber is compact in structure and is difficult to dye due to the lack of dye-philic groups by introducing cationic dyeable sodium sulfonate groups into a macromolecular main chain, thereby providing a feasible production process route for improving the dyeing property of the polyester fiber. A cationic dye dyeable modified polyester (CDP) was internationally developed by DuPont in 1978, which generates sodium ethylene terephthalate-5-Sulfonate (SIPEG) by the ester exchange reaction of dimethyl isophthalate-5-Sulfonate (SIPM) with ethylene glycol, which is generally abbreviated as DMT process technology. In the polyester reaction process, SIPEG (third monomer for short) and esterified substances are fully mixed, then the polycondensation reaction is carried out between the esterified substances, the sulfonic acid group of the SIPEG is introduced into the molecular chain of the conventional polyester product, so as to prepare the cationic dyeable polymer (CDP for short), and further produce the cationic polyester fiber, and the uniform effect of the mixing of the SIPEG (third monomer for short) and the esterified substances has obvious influence on the spinnability and dyeing stability in the subsequent fiber processing process. The synthesis process of 5-sodium dimethyl isophthalate (SIPM) includes the first sulfonation of isophthalic acid and fuming sulfuric acid and the subsequent esterification of isophthalic acid and methanol to produce 5-sodium dimethyl isophthalate (SIPM). In the process route, a methyl functional group is introduced in the synthetic process of the cationic polyester fiber, and because methyl can generate the action of a chain stopper in the synthetic process of the polyester, the use of methanol is not beneficial to realizing the stable molecular bond forming process of linear polymer molecular chains, thus being not beneficial to the post-processing treatment of the fiber, and the fiber has the phenomenon of unstable dyeing in the post-processing process. Although methanol does not enter the chemical molecular structure of the final product in the whole synthesis process, the methanol enters a production system due to the participation of esterification reaction and ester exchange reaction, and the risk of entering the environment by volatile organic compounds brought by the methanol is increased. Because methanol has the characteristics of high volatility, extremely high flammability and explosiveness and harmfulness to human bodies, how to avoid the use of methanol to improve the environment and reduce the potential safety hazard becomes a problem that the production process of the cationic polyester fiber needs to pay high attention. However, because the direct esterification reaction of sodium 5-Sulfoisophthalate (SIPA) and ethylene glycol can also generate adverse factors in the use process of the product, the technology cannot be put into practical application in time delay, and the main reason is that after the sulfonation reaction of isophthalic acid and fuming sulfuric acid, the difficulty of the continuous esterification reaction with ethylene glycol is obviously increased because a sulfonic group with larger occupied space is introduced into the molecular structure, and the unstable esterification reaction in the synthesis process can influence the esterification rate, thereby influencing the stability of the polymerization degree of the subsequent polycondensation reaction, being not beneficial to the improvement of the spinnability in the fiber processing process and being not beneficial to the improvement of the final dyeing stability of the fiber product. Research shows that linear molecular chain instability can be generated after products of direct esterification reaction of isophthalic acid-5-sodium Sulfonate (SIPA) and ethylene glycol enter a polyester molecular chain, the phenomenon is very obvious in the polymerization reaction process, a large amount of yarn breakage is also shown in the spinning process, the strength and the elongation of the products are not regular, and even industrial production cannot be formed. Therefore, although DuPont in the United states has invented a method for producing cationic polyester fibers in 1978, moreover, the company, many scientific research institutions and manufacturing factories at home and abroad have not abandoned research and test on avoiding the use of methanol, hope to realize the synthesis of sodium ethylene glycol isophthalate-5-Sulfonate (SIPEG) by a direct esterification method of ethylene glycol, meanwhile, the polyester third monomer synthesized by the method can be applied to the production of melt direct spinning cationic polyester filaments and short fibers, finally obtaining the production mode of a large-capacity production device and fiber products with high spinnability and dyeing stability, but has not obtained substantial breakthrough so far, namely, the industrial production of the high-capacity high-spinnability and dyeing stability of the melt direct spinning cationic polyester fiber (filament and short fiber) which is synthesized into the third monomer based on the ethylene glycol direct esterification method can not be realized.

The present invention has been made based on this.

Disclosure of Invention

Aiming at the problems that the ester exchange method, namely DMT method technology, must use methanol, so that volatile organic matters are generated to influence the environment and increase the potential safety hazard of production, and simultaneously aiming at solving the problem that sodium m-phthalate-5-Sulfonate (SIPA) is directly subjected to esterification reaction with glycol but cannot be applied to the production of cationic polyester fibers, the invention provides a process formula for synthesizing a third monomer of sodium m-phthalate glycol ester-5-Sulfonate (SIPEG) based on a glycol direct esterification method and a corresponding production process, and can realize the industrial production of cationic polyester filaments and short fibers.

In order to achieve the purpose, the technical scheme adopted by the invention is as follows:

a production process of a cationic polyester melt comprises the following steps:

(1) using sodium 5-Sulfoisophthalate (SIPA) as raw material, esterifying in phosphoric acid series and acid radical ion (H) in system⁺) The generated composite catalyst is catalyzed to carry out esterification reaction with glycol in an esterification reaction kettle, and the esterification product of ethylene glycol isophthalate-5-sodium Sulfonate (SIPEG) is finally obtained under the conditions of certain reaction temperature and uniform stirring;

(2) taking purified terephthalic acid as a raw material, carrying out esterification reaction with ethylene glycol in an esterification reaction kettle under the action of an antimony catalyst, and finally obtaining an esterified ethylene terephthalate (BHET) under the conditions of certain reaction temperature, reaction pressure and uniform stirring;

(3) esterified ethylene terephthalate (BHET) and sodium isophthalate-5-Sulfonate (SIPEG) are mixed in an esterification reaction kettle after being pre-alcoholyzed by ethylene glycol, the esterification rate is further improved after the materials are uniformly stirred and mixed, and a mixed esterified material which is fully and uniformly mixed is formed;

(4) putting the esterified substance obtained in the step (3) into an upper chamber of a pre-polycondensation reaction kettle, performing pre-polycondensation reaction under the combined action of an ethylene glycol spraying system and a vacuum unit, opening a regulating valve to enable the esterified substance to enter a lower chamber of the pre-polycondensation reaction kettle, uniformly stirring under the environment of obviously improving the vacuum degree to continue the polycondensation reaction, and finishing the pre-polycondensation reaction under the condition that the intrinsic viscosity reaches 0.20-0.28 to obtain a pre-polycondensation reactant;

in the process, a third monomer (sodium ethylene isophthalate-5-Sulfonate (SIPEG)) is uniformly dispersed under the condition of material mixing and is subjected to pre-polycondensation reaction, glycol removed by the polycondensation reaction and a small amount of low-molecular polymer enter a glycol spraying system, and are separated from the reaction system under the dual actions of the adsorption action of low-temperature glycol and vacuum power.

(5) And (3) conveying the pre-polycondensation reaction product obtained in the step (4) into a final polycondensation reaction kettle, and obtaining the cationic polyester melt under the condition that the intrinsic viscosity of the polymer is 0.55-0.59.

In the process, the third monomer is uniformly dispersed under the condition of material mixing and is subjected to final polycondensation, ethylene glycol and a small amount of low-molecular polymer removed by the polycondensation enter an ethylene glycol spraying system, and are separated from the reaction system under the dual actions of the adsorption action and the vacuum power of the low-temperature ethylene glycol.

And (3) continuously separating the byproduct water of the esterification reaction in the steps (1) and (2) from the reaction system through a rectifying tower. The esterification reaction is continuously carried out in the positive direction.

The pre-polycondensation reaction kettle in the step (5) comprises a stirrer. Under the action of a horizontal stirrer, the precondensate is provided with enhanced surface updating opportunity, and along with the continuous flowing of materials, the devolatilization effect of the glycol is more obvious, which shows that the viscosity of the materials is continuously improved, and the shearing load of the materials is continuously increased from the load data of the stirrer.

In the step (1), the mass of the composite catalyst added is 0.15-0.2% of that of the sodium ethylene glycol isophthalate-5-sulfonate, and the reaction temperature in the step (1) is 170-190 ℃.

The esterification reaction temperature in the step (2) is 258-262 ℃, the reaction pressure is 45-55 Kpa, and the material level of the esterification reaction kettle is 80-90%.

In the step (3), the mass ratio of esterified ethylene terephthalate (BHET) to sodium ethylene isophthalate-5-Sulfonate (SIPEG) is 47.0-49.0: 1.

the temperature of the upper pre-polycondensation chamber in the step (4) is 265-268 ℃, the temperature of the lower pre-polycondensation chamber is 272-278 ℃, the material level of the upper pre-polycondensation chamber in the step (4) is 35-45%, the material level of the lower pre-polycondensation chamber is 69-75%, the vacuum degree of the upper pre-polycondensation chamber in the step (4) is 15-18 KPa, and the vacuum degree of the lower pre-polycondensation chamber is 1.2-1.8 KPa.

In the step (5), the final polycondensation reaction temperature is 278-285 ℃, the material level is 18-22%, the vacuum degree is 250-350 Pa, and the speed of the stirrer is 2.95-3.20 rpm.

A production process of a cationic polyester melt is applied to the production of filaments, each filament production line firstly receives the cationic polyester melt from a polymerization production process through a melt heat-insulation high-pressure pipeline, the melt is metered through the high precision of a metering pump after entering a box body of each filament production line, and then is gradually crystallized and solidified in a slow cooling zone through the high precision filtration of a component and the stable cooling of side blowing, the number of holes of a spinneret plate is 36-144, namely the number of fiber of each strand of filament bundle is below 200, and a stable side blowing system can completely meet the requirement of fiber crystallization forming. The cationic polyester melt enters a winding system in a spinning shape after being solidified, and before entering, the cohesion performance of filament bundles after fiber forming must be increased through oiling. A winding system of fiber tows fully soaked by oil agent comprises a cylindrical cam type yarn guide mechanism, a yarn guide wheel, a winding machine and a winding machine, wherein the circumferential yarn path of the fiber is positioned by the cylindrical cam type yarn guide mechanism, the reasonable turning arc radius of the yarn guide wheel ensures that the impact vibration of the yarn tows is relieved and the package convex edge is avoided, during the period, the tension of each yarn is adjusted to be uniform, the yarn path gap is stable, each yarn cake is ensured to be accurately formed and positioned after entering the winding machine, finally, the yarn cake with fixed weight is regularly formed on the winding machine which runs at high speed, the manufacture of the final product cationic polyester filament yarn is finished, the winding speed is determined according to the characteristics of pre-oriented yarn POY, the crystallization area of a slow cooling area and a fiber collecting point during spinning are selected, the cationic polyester POY fiber capable of meeting post-processing is obtained by combining the control factors, particularly, the selection of the elongation must be moderate, which causes the breakage of the post-processing, and the too high tension adjustment of the post-processing is difficult to control, thereby producing the drawn yarn with uneven strength and elongation, which is not beneficial to the normal operation of the weaving process and can produce the quality hidden trouble of uneven fabric dyeing.

The heating temperature of the heat conducting oil of the spinning box body is 278-285 ℃, the side blowing temperature is 26-29 ℃, and the winding speed is 2850-3000 m/min.

A production process of a cationic polyester melt is applied to the production of short fibers and comprises the following steps: the method comprises the steps that a short fiber production line receives a cationic polyester melt from a polymerization production process through a melt heat-insulation high-pressure pipeline, the melt enters a box body of the short fiber production line and is measured by a metering pump at high precision, and then is crystallized gradually in a slow cooling area to be in a solidification state through high-precision filtering of a component and stable cooling of circular blowing air, and the requirements on stable air supply and temperature control of a circular blowing air system are high due to the fact that the number of holes of a spinneret plate is as high as about 4000, and each fiber can be ensured to be crystallized and solidified slowly from a melting state. The cationic polyester melt enters a winding system in a spinning shape after being solidified, the number of spinning holes of each position of short fibers is very high, the tows of 32 or 48 positions of a production line are finally gathered into one tow, the number of the fibers is as high as 12-20 ten thousand, so the cohesion performance of the fibers needs to be improved through two oiling processes, the oil can eliminate the electrostatic action between the fibers and improve the smoothness performance of the fibers, the friction negative effect of the fibers and metal parts is relieved, slit type tow infiltration is adopted during circular blowing cooling forming in the first oiling process, the oil infiltration is ensured to be uniform, oil is adopted for each position to be circularly infiltrated by an oil tanker before the tows enter the stranding winding process in the second oiling process, and the requirement on the stable operation of the tows in a yarn channel is very high. The tows of each position are provided with pulp block detectors to ensure that unqualified tows cannot enter the plied yarns, the single-strand tows of each spinning position form the plied yarns after changing the moving direction through the godet, the plied tows are drawn to the feeding wheel by the seven-roller and five-roller tractors, and the tows are fully tensioned under the reasonable action of gaps and can be smoothly stripped from the lower part of the feeding wheel to enter the yarn containing barrel. The pre-spinning of the short fiber is received by a yarn containing barrel, and the short fiber is produced on a packaging machine through bundling, water bath drafting, first drafting, second drafting, tension heat setting, third drafting, curling, relaxation heat setting, traction tension and cutting, and finally the short fiber package with fixed weight is produced, thus finishing the manufacture of the final product of the cationic polyester short fiber. The bundling function is to enable the tows with the total denier of about 350 ten thousand decitex to enter a drafting process with uniform tension and certain tow width, so that the uniformity of each fiber index in subsequent processing is ensured; the water bath drafting is to further adjust the pre-crystallization performance of the tows by playing a role in swelling and plasticizing the fibers so as to stably thermally stretch the tows; because the stress of the short fiber is larger when the short fiber is subjected to hot stretching by steam heating, three hot stretching steps are adopted to improve the stability of the strength and the elongation index; although the short fiber subjected to hot drawing obtains higher orientation degree, the regularity of a high molecular structure is still unstable, eighteen steam-heated tension heat setting rollers are generally adopted to improve the crystallinity of the fiber and fix the orientation structure of the fiber so as to ensure that the short fiber obtains higher strength and lower elongation in order to avoid the occurrence of polymer structure de-orientation in subsequent processing, the first hot rollers are used for removing water brought in the process of drawing the filament bundle and improving the temperature of the filament bundle, and the second hot rollers are used for further crystallizing the filament bundle; the short fiber subjected to hot stretching and hot setting has poor holding force, the friction coefficient between the fibers needs to be improved through curling processing so as to improve the holding effect, meanwhile, the elasticity of the short fiber is increased, so that the fibers have good holding and warm-keeping performance, the curling is formed by enabling tows to pass through a pair of rotary curling wheels, enabling the tows to enter a curling box through clamping, and after the curling box is filled with the tows, the tows are bent due to obstruction, so that the curling effect is generated; the crimped short fibers also need to reduce the water content in a free relaxed state and further eliminate the internal stress generated when the hot-stretched buckles are crimped, so that the thermal shrinkage of the short fibers is reduced and the dimensional stability is improved, namely, the loose heat setting is generally carried out by three parts of chain plate type wire feeding, wire loading and hot air blowing; the short fiber tows after loose heat setting pass through a knot catcher to detect the knot of the tows, then the tension of the tows is adjusted through a traction machine and a tension bracket, the tows are fed into a cutting machine through a yarn guide compression roller to be formed, and finally the tows are packaged into finished products.

The circular blowing temperature is 28-30 ℃, the water bath drafting temperature is 65-70 ℃, the first drafting speed is 70-75 m/min, the first drafting temperature is 80-90 ℃, the second drafting speed is 190-210 m/min, the second drafting temperature is 100-120 ℃, the third drafting speed is 200-215 m/min, the third drafting temperature is 150-170 ℃, the tension heat setting temperature is 175-190 ℃, the curling forming speed is 210-220 m/min, the curling preheating temperature is 90-100 ℃, the curling main pressure is 300-350 Kpa, and the relaxation heat setting temperature is 120-130 ℃.

The isophthalic acid-5-sodium Sulfonate (SIPA) has white powder appearance, purity of more than or equal to 99 percent, acid value of 418 +/-3 mgKOH/g and sulfate (SO 4)^2-) Less than or equal to 500ppm, iron content (Fe) less than or equal to 10ppm, chloride (Cl)^-) Less than or equal to 10ppm, transmittance more than or equal to 90 percent, water solubility of 100 percent and chroma (20 percent water solution platinum)Cobalt is less than or equal to 20APHA, water content is less than or equal to 0.2 percent

The Purified Terephthalic Acid (PTA) has the appearance of white powder, the purity is more than or equal to 99 percent, the acid value is 675 +/-2 mgKOH/g, the content of p-toluic acid (PT acid) is less than or equal to 150ppm, 4-hydroxybenzaldehyde (4-CBA) is less than or equal to 25ppm, the hue b value is less than or equal to 1.5, the ash content is less than or equal to 8ppm, the total metal content is less than or equal to 5ppm, the iron content is less than or equal to 1ppm, the chroma (20 percent aqueous solution platinum-cobalt) is less than or equal to 10APHA, and the water content

The initial boiling point of the ethylene glycol (MEG) is more than or equal to 196 ℃, the water content is less than or equal to 0.1 percent, the acidity (calculated by acetic acid) is less than or equal to 0.002 percent, the iron content is less than or equal to 0.1ppm, the ash content is less than or equal to 10ppm, the aldehyde content (calculated by formaldehyde) is less than or equal to 10ppm, the contents of diethylene glycol and triethylene glycol are less than or equal to 0.1 percent, and in addition, the light transmittance is more than or equal to 70(220nm), more than or equal to 90(275nm)

Refined phthalic acid (PTA), ethylene glycol (MEG) and sodium 5-Sulfoisophthalate (SIPA) are three monomers for synthesizing cationic polyester fibers, and the production processes of the monomers are respectively explained as follows.

The process for preparing the isophthalic acid-5-sodium Sulfonate (SIPA) comprises the following steps: performing electrophilic substitution sulfonation reaction on isophthalic acid (IPA) and fuming sulfuric acid at 70-80 ℃, dissolving and cleaning the mixture by desalted water, filtering impurities, decoloring the mixture by activated carbon, crystallizing and separating out the mixture, and finally drying the mixture by using steam at 180 ℃ to obtain a finished product.

The process for preparing purified phthalic acid (PTA) comprises the following steps: carrying out oxidation reaction on p-xylene (PX) and oxygen in air at 185-195 ℃, wherein acetic acid is used as a solvent, cobalt acetate and manganese acetate are used as catalysts, hydrogen bromide or tetrabromoethane is used as an accelerator, and the reaction pressure is 0.9-1.1 MPa. Refining the crude product through catalytic hydrogenation reduction reaction, reducing 4-hydroxybenzaldehyde (4-BCA) which is not completely reacted in the oxidation process of p-xylene into water-soluble p-toluic acid (PT acid) under the conditions of 6.8MPa pressure and 280 ℃, then removing the PT acid through water washing, crystallizing and drying to obtain the finished product.

The process for preparing ethylene glycol (MEG) is: carrying out heterogeneous catalysis direct hydration reaction on ethylene oxide and water at the temperature of 80-130 ℃ and under the pressure of 0.8-1.6 MPa, wherein the reaction molar ratio of the water to the ethylene oxide is 3-7: 1, the conversion rate of the ethylene oxide is 96-98 percent, and the selectivity of the ethylene glycol is 97-98 percent

The direct esterification synthesis process of the third monomer of sodium ethylene glycol isophthalate-5-Sulfonate (SIPEG) adopts an esterification reaction kettle, and a filler type rectifying tower is used for separating the reaction by-product water and the glycol which is one of the raw materials. The esterification reaction kettle comprises a reactor serving as a pressure container (the volume is 8.6m3, the height is 2.952m, the design pressure is-0.1-0.30 MPa, the design temperature is 220 ℃), a stirrer, a transmission motor (the motor power is 7.5 kilowatts, the three-phase four-wire system, the insulation grade is IP65, the output rotating speed of a reduction gearbox is 84rpm), a conduction oil heating coil system (the design pressure is 1.2MPa, the design temperature is 300 ℃), the connecting part of the stirrer and the reactor is a reactor sealing device (double-end-face mechanical seal with a dynamic ring and a static ring), the inner wall of the reactor is made of 316L high-corrosion-resistant stainless steel material, a filler type rectifying tower is made of stainless steel filler (the filler height is 5.5 m, the cylinder body design pressure is-0.1-0.35 MPa, the design temperature is 220 ℃), the gas phase composition enters a tubular condenser (the shell side design pressure is 0.6MPa, the design temperature is 70 ℃), the tube side design pressure is-0.1-0.35 MPa, design temperature 120 deg.C), the esterification water was received in a collection tank and metered (volume 0.8m3, height 2.275 m). The method comprises the steps of carrying out esterification reaction on isophthalic acid-5-sodium Sulfonate (SIPA), ethylene glycol and an auxiliary agent (a catalyst and an anti-etherifying agent) in a reactor, wherein activation energy required by the reaction and heat energy for heating and separating materials are provided by a heat conduction oil secondary system of a polymerization device, the heat energy is transferred to the materials in the reactor through a heat conduction oil circulating system heated by a boiler and a stainless steel coil in the reactor, the heat transfer area of the coil is designed to be 20m2, a two-layer three-blade CBY type stirrer (the diameter of a blade is 1050mm) is combined with two phase materials, so that the isophthalic acid-5-sodium Sulfonate (SIPA) and the ethylene glycol are subjected to high-efficiency mass and heat transfer, the esterification reaction is carried out at the reaction activation energy reaching temperature (about 180 ℃), and the formal reaction start can be judged from the temperature change of the top of a rectifying. The reaction temperature is set by a DCS control system of a central control room, the heat conducting oil pneumatic thin film valve is automatically adjusted under the action of preset PID parameters, the reaction temperature is accurately measured and controlled, temperature and pressure information in the reactor are measured in situ by a fixed instrument, and remote monitoring is realized by the DCS system. The gas phase mixture of byproduct esterified water and glycol generated by the reaction is separated after entering a rectifying tower, the esterified water is extracted from the top of the rectifying tower, preliminary cooling condensation is realized through a dephlegmator arranged at the top of the rectifying tower, the esterified water mixed with gas phase and liquid phase enters a tubular condenser to realize complete condensation, and the liquid esterified water enters a collecting tank for storage. The collecting tank is provided with a magnetic turning plate liquid level meter and a pressure diaphragm type liquid level meter, the magnetic turning plate liquid level meter is used for field observation, and the pressure diaphragm type liquid level meter is remotely transmitted to a DCS system of a central control room through data acquisition, so that an operator can master the amount of generated esterification water in time, and the conversion degree of the esterification reaction is effectively judged.

The concentration of the solution of the 5-sodium sulfoethylene glycol isophthalate (SIPEG) obtained by the esterification reaction is 35%, the solution is conveyed to a first reaction chamber of a second esterification reactor of a polymerization device through a shielding pump, and materials in the reaction chamber are further uniformly dispersed by a third monomer through a homogenizer, so that the improvement of the dyeing stability after the fiber processing is facilitated. Fully mixing the mixture to reach a specified esterification rate, feeding the mixed esterified substance into a pre-polycondensation reaction kettle and a final polycondensation reaction kettle in sequence, controlling the polymerization degree, namely the viscosity of polyester melt, which reaches the requirement of the cationic polyester fiber by a production process after repeated optimization, and feeding the polyester melt into a spinning production system through a melt conveying pipeline to finally obtain a formed fiber product.

Compared with the prior art, the invention has the advantages that:

1) compared with the prior art of ester exchange method, namely DMT method, the invention has the following technical effects: the method can solve the problem of difficult chemical reaction when the isophthalic acid-5-sodium Sulfonate (SIPA) is directly subjected to esterification reaction with ethylene glycol, has stable product purity, effectively controlled side reaction, stable polymerization reaction and effectively controlled polymerization degree of a cationic polymer, reduces the phenomenon of instability of molecular chains in the cationic polyester fiber, controls the strength and the elongation of the fiber product stably, and has higher first-class yield in the fiber manufacturing process, thereby realizing industrial production. Because methanol is not used in the production process of the raw material sodium 5-Sulfoisophthalate (SIPA), a methyl functional group is not introduced in the synthesis process of the cationic polyester fiber, and because methyl can generate the action of a chain stopper in the synthesis process of the polyester, the methanol is not used, so that the stable molecular bond forming process of a linear polymer molecular chain is realized, the post-processing treatment of the fiber is facilitated, and the spinnability and the dyeing property of the fiber are improved.

2) Methanol is not used in the synthesis process of the raw material of the isophthalic acid-5-sodium Sulfonate (SIPA), and a methanol byproduct is not generated when the isophthalic acid-5-sodium Sulfonate (SIPA) is directly esterified with the ethylene glycol, so that the adverse effects of the methanol on the environment, the safe production and the protection of workers are avoided due to the change of the synthesis process route, and because the methanol is a high-volatility organic matter, the methanol has extremely high flammability and explosiveness, the toxicity of the methanol has great influence on the nervous system and the blood system of a human body, and the green and environment-friendly production of the synthesis process of the cationic polyester fiber is realized by using the technology of the invention.

3) The production process of the filament and the short fiber under the prior technical scheme is changed: the isophthalic acid-5-sodium Sulfonate (SIPA) directly carries out esterification reaction with ethylene glycol, methanol is not used any more, the linear polymer molecular chain is beneficial to realizing stable molecular bond, the synthetic technology breaks through the solution that ethylene glycol macromolecules are difficult to enter the isophthalic acid-5-sodium Sulfonate (SIPA) macromolecular structure, the generated cationic polyester has completely different linear high polymer crystallization performance from the prior art, and the ion exchange performance of the subsequent cationic dye is changed due to the change of the form and the process that the ethylene glycol macromolecules enter the isophthalic acid-5-sodium Sulfonate (SIPA) macromolecular structure. Based on these changes, the spinning conditions of the filaments and the staple fibers, the post-drawing processability and the dyeing stability of the final product also change significantly to different degrees. For the filament, the slow cooling zone is determined again according to the change of the crystalline property of the cationic polyester, the beam-concentrating point of the fiber is adjusted, so that the spinning forming effect is improved, meanwhile, the spinning speed is changed, the pre-orientation degree is comprehensively adjusted, the strength and the elongation of the cationic polyester POY are controlled, the requirement of post-processing drafting yarn is met, meanwhile, the post-processing drafting temperature of the fiber is adjusted by coordinating users, the processing drafting property of the filament is obviously improved, and the dyeing stability is also obviously improved. The method comprises the steps of (1) adjusting short fibers by dividing the short fibers into two parts, wherein firstly, a slow cooling area is re-determined according to the change of the crystalline property of cationic polyester and the spinning characteristic of the short fibers, the temperature and the air volume of circular blowing are changed, the ratio of two effective components in an oiling agent is adjusted according to the change of the cohesive property of the fibers, and the slit oiling of the oiling agent is correspondingly adjusted (the slit oiling is realized by fully utilizing an inner circular blowing device, oiling is obtained at the initial stage of spinning forming, and the oiling effect can be ensured for a spinneret plate with 4000 pores, and the oiling is carried out during subsequent winding), the angle and the oiling amount are adjusted, meanwhile, the spinning speed is changed, the pre-orientation degree is adjusted, and the crystallization property of the fibers is; and secondly, the water bath temperature and the three-pass drafting temperature are changed in the drafting stage, the proportion of two effective components in the oiling agent is readjusted according to the change of the cohesion property and the smoothness property of the fiber, the oiling position and the oiling amount of the oiling agent are correspondingly adjusted, the curling temperature, the curling main pressure and the oil spraying angle are also adjusted according to the change of the cohesion property and the elasticity of the fiber, the hot air temperature and the air supply amount of subsequent relaxation heat setting are optimized, the heat shrinkage property of the fiber is optimized, the dimensional stability of the fiber is improved, meanwhile, the tension adjustment before cutting is facilitated, and the drafting property of the short fiber is obviously improved. Due to the fact that the crystallization performance of the cationic polyester changes and the forming process of the molecular structure influencing dyeing is changed obviously, the spinnability and the dyeing style of the short fiber applied to yarn processing are changed obviously by adjusting the spinning forming condition of the short fiber, changing the hot stretching process, adapting the curling performance and optimizing tension and relaxation heat setting, and the comprehensive requirements of a user on dyeing and fiber hand feeling are met.

4) By changing the prior process technology of a third monomer of the cationic polyester, namely, sodium ethylene glycol isophthalate-5-Sulfonate (SIPEG), the synthesized raw material is changed from dimethyl isophthalate-5-Sulfonate (SIPM) to sodium isophthalic acid-5-Sulfonate (SIPA), and the raw material consumption in the production of the polyester is also reduced to 20kg/t from 23 kg/t. The main reason is that the cationic dyeable sulfonic acid groups are counted in number, i.e. in mole number, in the polyester molecular chain, so that the raw material consumption is calculated differently. In the case of consistent dyeing depth, the consumption of the raw material is measured by mass number, the molecular weight of SIPM is 296.23, while the molecular weight of SIPA is 268.18, the molecular weight of SIPA is smaller than that of SIPM, and the consumption of the mass number of the raw material is reduced.

5) Because the synthesis process route of the ethylene glycol isophthalate-5-sodium Sulfonate (SIPEG) is changed, the production process of the raw material of the sodium sulfoisophthalate-5-Sulfonate (SIPA) only carries out sulfonation reaction of fuming sulfuric acid, and methanol is not used for esterification reaction, the reaction heat in the production process of the raw material is reduced, the problem of chemical reaction conversion rate of the esterification reaction of the sodium sulfoisophthalate-5-Sulfonate (SIPA) and the methanol is avoided, and the low consumption of the raw material production is realized. Therefore, the double consumption of energy and materials is reduced through the change of a chemical synthesis process route, and the aim of reducing the production cost of an industrial chain is further fulfilled.

Drawings

FIG. 1 is a flow chart of the production process of the cationic polyester melt production process applied to short fibers or filaments.

Detailed Description

Example 1 (production of cationic polyester melt)

(1) Using sodium 5-Sulfoisophthalate (SIPA) as raw material, esterifying in phosphoric acid series and acid radical ion (H) in system⁺) The generated composite catalyst is catalyzed to carry out esterification reaction with glycol in an esterification reaction kettle, and the esterification product of ethylene glycol isophthalate-5-sodium Sulfonate (SIPEG) is finally obtained under the conditions of certain reaction temperature and uniform stirring; the mass of the added composite catalyst is 0.2% of the mass of the isophthalic acid glycol ester-5-sodium sulfonate, and the reaction temperature in the step (1) is 170-190 ℃.

(2) Taking purified terephthalic acid as a raw material, carrying out esterification reaction with ethylene glycol in an esterification reaction kettle under the action of an antimony catalyst, and finally obtaining an esterified ethylene terephthalate (BHET) under the conditions of certain reaction temperature, reaction pressure and uniform stirring; the esterification reaction temperature in the step (2) is 258-262 ℃, the reaction pressure is 45-55 Kpa, and the material level of the esterification reaction kettle is 80-90%.

(3) Esterified ethylene terephthalate (BHET) and sodium isophthalate-5-Sulfonate (SIPEG) are mixed in an esterification reaction kettle after being pre-alcoholyzed by ethylene glycol, the esterification rate is further improved after the materials are uniformly stirred and mixed, and an esterified material which is fully and uniformly mixed is formed; in the step (3), the mass ratio of esterified ethylene terephthalate (BHET) to sodium ethylene isophthalate-5-Sulfonate (SIPEG) is 47.0-49.0: 1.

(4) putting the esterified substance obtained in the step (3) into an upper chamber of a pre-polycondensation reaction kettle, carrying out pre-polycondensation reaction under the combined action of an ethylene glycol spraying system and a vacuum unit, opening a regulating valve to enable the esterified substance to enter a lower chamber of the pre-polycondensation reaction kettle, stirring uniformly under the environment of obviously improving the vacuum degree to continue the polycondensation reaction, and finishing the pre-polycondensation reaction under the condition that the inherent viscosity of a prepolymer reaches 0.25 to obtain a pre-polycondensation reactant; the temperature of the upper pre-polycondensation chamber in the step (4) is 265-268 ℃, the temperature of the lower pre-polycondensation chamber is 272-278 ℃, the material level of the upper pre-polycondensation chamber in the step (4) is 35-45%, the material level of the lower pre-polycondensation chamber is 69-75%, the vacuum degree of the upper pre-polycondensation chamber in the step (4) is 15-18 KPa, and the vacuum degree of the lower pre-polycondensation chamber is 1.2-1.8 KPa.

In the process, a third monomer (sodium ethylene isophthalate-5-Sulfonate (SIPEG)) is uniformly dispersed under the condition of material mixing and is subjected to pre-polycondensation reaction, glycol removed by the polycondensation reaction and a small amount of low-molecular polymer enter a glycol spraying system, and are separated from the reaction system under the dual actions of the adsorption action of low-temperature glycol and vacuum power.

(5) And (3) conveying the pre-polycondensation reaction product obtained in the step (4) into a final polycondensation reaction kettle to obtain the cationic polyester melt under the condition that the intrinsic viscosity of the polymer is 0.58. In the step (5), the final polycondensation reaction temperature is 278-285 ℃, the material level is 18-22%, the vacuum degree is 250-350 Pa, and the speed of the stirrer is 2.95-3.20 revolutions per minute.

Examples 2 to 6

The procedure is as in example 1 except that the catalyst or the amount of catalyst added in step 1 is different, as specified in the following table:

the key to the research on the synthesis of the sodium ethylene glycol isophthalate-5-sulfonate is to select a proper catalyst, because some side reactions can be generated in the chemical reaction process, and the control of the side reactions is not facilitated due to the excessively long reaction time. Analysis of the mechanism of esterification reaction, acid ion (H)⁺) The method plays a role in catalysis, but a large amount of reaction heat is generated in the actual process of the reaction, and the method is not beneficial to the effective control of the esterification reaction, so that certain chemical reagents are required to be selected for compounding the catalyst, and the catalytic effect is optimized. Through repeated experimental comparison, phosphate ester is preferably selected from phosphate, phosphate ester and antimony compound. The index for measuring the effect of the catalyst is to detect the purity of the final product within 1 hour of reaction time, the purity can be determined by the acid value of the product, the esterification rate is continuously improved along with the proceeding of the esterification reaction, the acid value in SIPA molecules is continuously reduced, namely, the acid (SIPA) and the alcohol (glycol) are continuously subjected to the esterification reaction to generate esterified ethylene glycol isophthalate-5-sodium Sulfonate (SIPEG), the low acid value indicates that the conversion rate of the esterification reaction is high, and also indicates that the purity of the product is high, thereby being more beneficial to the subsequent polycondensation reaction to produce the polyester melt suitable for spinning. As can be seen from the relevant tables of examples 2 to 6, the data of the acid value is 8mgKOH/g at the lowest, from the practical analysis of the condition of producing polyester melt by the subsequent polycondensation reaction, the too low acid value causes the phenomenon of poor spinning condition, and through the theoretical analysis, the theoretical analysis shows that the too high amount (0.3%) of the composite catalyst promotes the side reaction in the esterification reaction process, and some heterocyclic organic compounds generated by the side reaction are not good for the normal production control of spinning. Therefore, the content of the composite catalyst is optimized to be 0.15-0.20%, and in the range, the polyester melt with excellent spinning condition can be obtained through polycondensation.

Examples 7 to 10

The procedure is as in example 1 except that the intrinsic viscosity of the prepolymer in stage 4 is different, as specified in the following table:

the intrinsic viscosity of the materials in the pre-polycondensation reaction kettle can influence the further chemical reaction of final polycondensation, and the polymer is degraded in the continuous chain forming process, namely, the molecular chain of the high molecular compound can generate chemical decomposition under the influence of chemical reaction heat or a very small amount of oxygen, the molecular chain is broken, the chain is continuously formed, and the broken chain is broken at the same time, which is a special phenomenon in the polymer forming process. Therefore, polymers with too high polymerization degree can be generated due to too high reaction temperature or vacuum degree (the high polymerization degree is reflected by the intrinsic viscosity data), the polymers with too high polymerization degree and partial thermal decomposition are generated and enter the final polymerization kettle to aggravate thermal degradation or oxidative degradation, and finally the spinning performance of the polyester melt is negatively influenced, so that the proper data of the material intrinsic viscosity of the pre-polycondensation reaction kettle is obtained by optimization and is 0.20-0.28, and the polyester melt with excellent spinning condition can be obtained through the final polycondensation reaction in the range.

Examples 11 to 14

The procedure is as in example 1 except that the intrinsic viscosity of the polymer in step 5 is different, as specified in the following table:

the intrinsic viscosity of the material in the final polycondensation reaction kettle directly influences the spinning performance of the polyester melt, the polymer is partially degraded in the process of fast chain formation in the final polycondensation stage, the chemical reaction in the final polycondensation stage is further strengthened, a large amount of reaction heat is released in the process, and under the influence of the reaction heat, the high molecular compound is chemically decomposed to enable the molecular chain to generate a fracture phenomenon, namely, a special phenomenon that the molecular chain is fractured while continuously growing is generated in the final polycondensation stage, the decomposition degree can be judged by detecting the terminal carboxyl of the material in the final polycondensation reaction kettle, and the thermal degradation phenomenon of the material is obvious on the high side of the terminal carboxyl data. Thus, too high a reaction temperature or vacuum level may result in polymers with too high a degree of polymerization (as evidenced by the high degree of polymerization passing through the data for intrinsic viscosity), which may cause partially thermally decomposed polymers to enter the spinning system, which may exacerbate thermal degradation of the polyester melt, ultimately negatively affecting the spinning performance of the polyester melt. Too high reaction temperature or vacuum level may even cause strong thermal degradation of the degree of polymerization, manifested by a higher content of terminal carboxyl groups, and even a decrease in the intrinsic viscosity of the polyester melt, which may result in fibers of low strength and low elongation at the spinning stage, making post-processing of the fibers very difficult. Therefore, the proper data of the intrinsic viscosity of the material of the final polycondensation reaction kettle obtained through optimization is 0.55-0.59, and in the range, the polyester melt with excellent spinning condition can be obtained through the final polycondensation reaction.

Example 15 (production of filament)

A production process of a cationic polyester melt is applied to the production of filaments, each filament production line firstly receives the cationic polyester melt from a polymerization production process through a melt heat-insulation high-pressure pipeline, the melt is metered through the high precision of a metering pump after entering a box body of each filament production line, and then is crystallized gradually in a slow cooling zone to be in a solidification state through the high precision filtration of a component and the stable cooling of lateral blowing, the number of holes of a spinneret plate is 36-144, namely the number of fiber of each strand of filament bundle is below 200, and a stable lateral blowing system (the lateral blowing temperature is 26-28 ℃) can completely meet the requirement of fiber crystallization forming. The cationic polyester melt enters a winding system in a spinning shape after being solidified, and before entering, the cohesion performance of filament bundles after fiber forming must be increased through oiling. A winding system of fiber tows fully soaked by oil agent comprises a cylindrical cam type yarn guide mechanism, a yarn guide wheel, a winding machine and a winding machine, wherein the circumferential yarn path of the fiber is positioned by the cylindrical cam type yarn guide mechanism, the reasonable turning arc radius of the yarn guide wheel ensures that the impact vibration of the yarn tows is relieved and the package convex edge is avoided, during the period, the tension of each yarn is adjusted to be uniform, the yarn path gap is stable, each yarn cake is ensured to be accurately formed and positioned after entering the winding machine, finally, the yarn cake with fixed weight is regularly formed on the winding machine which runs at high speed, the manufacture of the final product cationic polyester filament yarn is finished, the winding speed is determined according to the characteristics of pre-oriented yarn POY, the crystallization area of a slow cooling area and a fiber collecting point during spinning are selected, the cationic polyester POY fiber capable of meeting post-processing is obtained by combining the control factors, particularly, the selection of elongation (the elongation is 138-140%) must be moderate, which causes yarn breakage in post-processing, and when the elongation is too high, the tension adjustment of post-processing is difficult to control, so that drawn yarns with uneven strength and elongation are generated, which is not favorable for normal weaving process, and potential quality hazards of uneven fabric dyeing are generated.

Wherein the heating temperature of the spinning box body heat conducting oil is 278-285 ℃, the side blowing temperature is 26-29 ℃, and the winding speed is 2850-3000 m/min.

Example 16 (short fiber production)

A production process of a cationic polyester melt is applied to the production of short fibers and comprises the following steps: the method comprises the steps that a short fiber production line receives a cationic polyester melt from a polymerization production process through a melt heat-insulation high-pressure pipeline, the melt enters a box body of the short fiber production line and is measured by a metering pump at high precision, and then is crystallized gradually in a slow cooling area to be in a solidification state through high-precision filtering of a component and stable cooling of circular blowing air, and the requirements on stable air supply and temperature control of a circular blowing air system are high due to the fact that the number of holes of a spinneret plate is as high as about 4000, and each fiber can be ensured to be crystallized and solidified slowly from a melting state. The cationic polyester melt enters a winding system in a spinning shape after being solidified, because the number of spinning holes of each position of short fibers is very high, and the tows of 32 or 48 positions of a production line are finally gathered into one tow, the number of the fibers is as high as 12-20 ten thousand, the cohesion performance of the fibers needs to be improved by oiling at two times, the short fiber oiling agent can eliminate the electrostatic action between the fibers and improve the smoothness performance of the fibers, the friction negative effect of the fibers and metal parts is relieved, slit type filament bundle infiltration is adopted during circular blowing cooling forming in the first oiling process, the oiling agent infiltration is ensured to be uniform, oil is adopted for each position to be circularly infiltrated by an oil tanker before the filament bundles enter the stranding winding process in the second oiling process, and the requirement on the stable operation of the filament bundles in a filament channel is very high. The tows of each position are provided with pulp block detectors to ensure that unqualified tows cannot enter the plied yarns, the single-strand tows of each spinning position form the plied yarns after changing the moving direction through the godet, the plied tows are drawn to the feeding wheel by the seven-roller and five-roller tractors, and the tows are fully tensioned under the reasonable action of gaps and can be smoothly stripped from the lower part of the feeding wheel to enter the yarn containing barrel. The pre-spinning of the short fiber is received by a yarn containing barrel, and the short fiber is produced on a packaging machine through bundling, water bath drafting, first drafting, second drafting, tension heat setting, third drafting, curling, relaxation heat setting, traction tension and cutting, and finally the short fiber package with fixed weight is produced, thus finishing the manufacture of the final product of the cationic polyester short fiber. The bundling function is to enable the tows with the total denier of about 350 ten thousand decitex to enter a drafting process with uniform tension and certain tow width, so that the uniformity of each fiber index in subsequent processing is ensured; the water bath drafting is to further adjust the pre-crystallization performance of the tows by playing a role in swelling and plasticizing the fibers so as to stably thermally stretch the tows; because the stress of the short fiber is larger when the short fiber is subjected to hot stretching by steam heating, three hot stretching steps are adopted to improve the stability of the strength and the elongation index; although the short fiber subjected to hot drawing obtains higher orientation degree, the regularity of a high molecular structure is still unstable, eighteen steam-heated tension heat setting rollers are generally adopted to improve the crystallinity of the fiber and fix the orientation structure of the fiber so as to ensure that the short fiber obtains higher strength and lower elongation in order to avoid the occurrence of polymer structure de-orientation in subsequent processing, the first hot rollers are used for removing water brought in the process of drawing the filament bundle and improving the temperature of the filament bundle, and the second hot rollers are used for further crystallizing the filament bundle; the short fiber subjected to hot stretching and hot setting has poor holding force, the friction coefficient between the fibers needs to be improved through curling processing so as to improve the holding effect, meanwhile, the elasticity of the short fiber is increased, so that the fibers have good holding and warm-keeping performance, the curling is formed by enabling tows to pass through a pair of rotary curling wheels, enabling the tows to enter a curling box through clamping, and after the curling box is filled with the tows, the tows are bent due to obstruction, so that the curling effect is generated; the crimped short fibers also need to reduce the water content in a free relaxed state and further eliminate the internal stress generated when the hot-stretched buckles are crimped, so that the thermal shrinkage of the short fibers is reduced and the dimensional stability is improved, namely, the loose heat setting is generally carried out by three parts of chain plate type wire feeding, wire loading and hot air blowing; the short fiber tows after loose heat setting pass through a knot catcher to detect the knot of the tows, then the tension of the tows is adjusted through a traction machine and a tension bracket, the tows are fed into a cutting machine through a yarn guide compression roller to be formed, and finally the tows are packaged into finished products.

Wherein the circular blowing temperature is 28-30 ℃, the water bath drafting temperature is 65-70 ℃, the first drafting speed is 70-75 m/min, the first drafting temperature is 80-90 ℃, the second drafting speed is 190-210 m/min, the second drafting temperature is 100-120 ℃, the third drafting speed is 200-215 m/min, the third drafting temperature is 150-170 ℃, the tension heat setting temperature is 175-190 ℃, the curling forming speed is 210-220 m/min, the curling preheating temperature is 90-100 ℃, the curling main pressure is 300-350 Kpa, and the relaxation heat setting temperature is 120-130 ℃.

Claims (10)

1. The production process of the cationic polyester melt is characterized by comprising the following steps:

(1) using m-phthalic acid-5-sodium sulfonate as raw material, and making it pass through phosphate series esterified substance and acid radical ion (H) of system⁺) The generated composite catalyst is catalyzed to carry out esterification reaction with glycol in an esterification reaction kettle, and the esterification product of the ethylene glycol isophthalate-5-sodium sulfonate is finally obtained under the conditions of certain reaction temperature and uniform stirring;

(2) taking purified terephthalic acid as a raw material, carrying out esterification reaction with ethylene glycol in an esterification reaction kettle under the action of an antimony catalyst, and finally obtaining an esterified ethylene glycol terephthalate under the conditions of certain reaction temperature, reaction pressure and uniform stirring;

(3) the esterification product ethylene glycol terephthalate and sodium isophthalate-5-sulfonate are mixed after being pre-alcoholyzed by ethylene glycol in an esterification reaction kettle, the esterification rate is further improved after the mixture is stirred and uniformly mixed, and the esterification product which is fully and uniformly mixed is formed;

(4) putting the esterified substance obtained in the step (3) into an upper chamber of a pre-polycondensation reaction kettle, performing pre-polycondensation reaction under the combined action of an ethylene glycol spraying system and a vacuum unit, opening a regulating valve to enable the esterified substance to enter a lower chamber of the pre-polycondensation reaction kettle, uniformly stirring under the environment of obviously improving the vacuum degree to continue the polycondensation reaction, and finishing the pre-polycondensation reaction under the condition that the intrinsic viscosity reaches 0.20-0.28 to obtain a pre-polycondensation reactant;

and (3) conveying the pre-polycondensation reaction product obtained in the step (4) into a final polycondensation reaction kettle to obtain the cationic polyester melt under the condition that the intrinsic viscosity of the polymer is 0.55-0.59.

2. A process for producing the cationic polyester melt according to claim 1, wherein: in the step (1), the mass of the composite catalyst added is 0.15-0.20% of that of the sodium ethylene glycol isophthalate-5-sulfonate, and the reaction temperature in the step (1) is 170-190 ℃.

3. A process for producing the cationic polyester melt according to claim 1, wherein: the esterification reaction temperature in the step (2) is 258-262 ℃, the reaction pressure is 45-55 Kpa, and the material level of the esterification reaction kettle is 80-90%.

4. A process for producing the cationic polyester melt according to claim 1, wherein: in the step (3), the mass ratio of esterified ethylene terephthalate (BHET) to sodium ethylene isophthalate-5-Sulfonate (SIPEG) is 47.0-49.0: 1.

5. a process for producing the cationic polyester melt according to claim 1, wherein: the temperature of the upper pre-polycondensation chamber in the step (4) is 265-268 ℃, the temperature of the lower pre-polycondensation chamber is 272-278 ℃, the material level of the upper pre-polycondensation chamber in the step (4) is 35-45%, the material level of the lower pre-polycondensation chamber is 69-75%, the vacuum degree of the upper pre-polycondensation chamber in the step (4) is 15-18 KPa, and the vacuum degree of the lower pre-polycondensation chamber is 1.2-1.8 KPa.

6. A process for producing the cationic polyester melt according to claim 1, wherein: in the step (5), the final polycondensation reaction temperature is 278-285 ℃, the material level is 18-22%, the vacuum degree is 250-350 Pa, and the speed of the stirrer is 2.95-3.20 revolutions per minute.

7. The process for producing a cationic polyester melt according to claim 1, applied to the production of filaments, comprising the steps of: the method comprises the following steps of (1) measuring a cationic polyester melt, filtering, stably cooling by cross air blowing, gradually crystallizing to be in a solidification state, enabling the cationic polyester melt to enter a winding system in a spinning shape after solidification, and oiling before entering to increase the cohesion performance of tows after fiber forming; and positioning and forming the oiled filament bundle to produce a spinning cake with a fixed weight, and finishing the manufacture of the final product, namely the cationic polyester filament.

8. A process for producing a filament using the process for producing a cationic polyester melt according to claim 7, wherein: the heating temperature of the heat conducting oil of the spinning box body is 278-285 ℃, the side blowing temperature is 26-29 ℃, and the winding speed is 2850-3000 m/min.

9. The process for producing a cationic polyester melt as claimed in claim 1, applied to the production of staple fibers, comprising the steps of: the method comprises the steps of metering a cationic polyester melt, performing stable cooling through filtering and circular blowing, gradually crystallizing to be in a solidification state, performing first oiling, performing slit type strand infiltration during circular blowing cooling forming of the first oiling, ensuring uniform oiling of an oiling agent, performing second oiling, performing circulating infiltration of an oil tanker before strand entering stranding winding of the second oiling, setting a size detector for each strand, performing pre-spinning on fibers subjected to twice oiling treatment, bundling, water bath drafting, first drafting, second drafting, tension heat setting, third drafting, curling, relaxation heat setting, traction tension, cutting off, and finally producing short fiber packages with fixed weight on a packaging machine.

10. A process for producing a cationic polyester melt according to claim 9 for use in the production of staple fibers, wherein: the circular blowing temperature is 28-30 ℃, the water bath drafting temperature is 65-70 ℃, the first drafting speed is 70-75 m/min, the first drafting temperature is 80-90 ℃, the second drafting speed is 190-210 m/min, the second drafting temperature is 100-120 ℃, the third drafting speed is 200-215 m/min, the third drafting temperature is 150-170 ℃, the tension heat setting temperature is 175-190 ℃, the curling forming speed is 210-220 m/min, the curling preheating temperature is 90-100 ℃, the curling main pressure is 300-350 Kpa, and the relaxation heat setting temperature is 120-130 ℃.