An industrial continuous manufacturing method for easily dyeable cationic polyester chips under normal pressure

Abstract

The present invention discloses an industrialized continuous manufacturing method of normal pressure cationic easy-dyeing (ECDP) polyester chips. The method comprises: mixing ethylene glycol solution containing titanium catalyst, terephthalic acid and ethylene glycol to prepare slurry; after the first step of esterification reaction, mixing with the third and fourth monomers and anti-ether agent, and carrying out the second step of esterification reaction; after the esterification oligomer is mixed with ethylene glycol containing titanium and antimony catalysts, heat stabilizer, etc., and then carrying out two steps of prepolymerization reaction and one step of final polymerization reaction, finally pelletizing to obtain ECDP polyester chips. The normal pressure cationic easy-dyeing polyester chips produced by the present invention have the advantages of stable product quality, good uniformity, good spinnability, good thermal stability, etc., and can provide a new polyester product that is easy to dye and environmentally friendly for subsequent printing and dyeing.

Description

Technical Field

[0001] The invention relates to the technical field of polymer synthetic materials, and in particular to an industrialized continuous manufacturing method of normal pressure cationic easy-to-dye polyester chips. Background Art

[0002] As a high polymer, polyester products have special molecular structural properties, and the fabrics made of them have excellent properties such as firmness, stiffness, wear resistance and dimensional stability. Polyester has been widely used as a fabric, but due to the dense structure of conventional polyester fibers, polyester fibers have the prominent disadvantage of poor dyeability. In the post-processing process of polyester fibers, there have always been problems such as poor dyeability and color fastness, high energy consumption in the dyeing process, large dye loss, and severe environmental pollution.

[0003] Cationic dyeable polyester (CDP) refers to a modified copolymer formed by copolymerizing 1,3-bis(hydroxyethyl)-5-sulfonate sodium (SIPE) with PET by adding a third monomer to the polyester macromolecular chain. The presence of -SO3Na groups in this fiber increases its affinity with cationic dyes, and its dyeability and color fastness are improved. Normal pressure cationic easy-dye polyester (ECDP) is a polyester dyeable polyester (CDP) that introduces a polyether-type flexible chain segment to reduce the regularity of PET macromolecules, thereby reducing crystallinity, lowering the glass transition temperature, and increasing fiber voids, achieving dyeing conditions at room temperature and pressure. ECDP fiber soon solved the dyeing problem of polyester fiber, and has broad application prospects in product diversification development, energy conservation and environmental protection, etc.

[0004] The patent "A polyester dyeable with cationic dyes under normal pressure, its production method and use (CN107474231A)" discloses a polyester dyeable with cationic dyes under normal pressure, its production method and use. It is mainly prepared by copolymerization of aromatic dibasic acid or its esterified derivative, aliphatic diol, polyalkylene glycol and aromatic dibasic acid or its esterified derivative with metal sulfonate group under the action of soluble catalyst.

[0005] Although this patent can realize the production of polyester dyeable with cationic dyes at normal pressure, it is only suitable for small-scale, intermittent / semi-continuous production and does not solve the problem of industrial continuous large-scale production. At the same time, the types and categories of catalysts and additives are also quite different from those of the present invention.

[0006] In the patent "A method for preparing normal pressure cation dyeable polyester fiber (CN107541803A)", a method for preparing normal pressure cation dyeable polyester is disclosed. The preparation method is as follows: firstly, dimethyl isophthalate-5-benzenesulfonate sodium, ethylene glycol, a catalyst and an anti-ether agent are mixed and then subjected to an ester exchange reaction, after the reaction is completed, ethylene glycol and sodium ethylene glycol are added for modulation, then terephthalic acid, ethylene glycol and a catalyst are mixed and then subjected to an esterification reaction, then the modulated product obtained after the ester exchange reaction and polyethylene glycol are added to the esterification reaction system that has reached the end point of the esterification reaction for polycondensation reaction to obtain a spinning melt, and finally the spinning melt is subjected to metering, extrusion, cooling, oiling, stretching, heat setting and winding to obtain a normal pressure cation dyeable polyester fiber.

[0007] Although this patent can realize the production of polyester dyeable with cationic dyes at normal pressure, it is also only suitable for small-scale, intermittent production and does not solve the problem of industrial continuous large-scale production. At the same time, the types and types of equipment, catalysts, and additives are also quite different from those of the present invention.

[0008] In the patent "A Copolymer Flame-retardant ECDP Polyester Chip and Its Preparation Method (CN 107129567A)", a copolymer flame-retardant ECDP polyester chip and its preparation method are disclosed. The preparation method is to use PTA, EG, SIPM, PEG, and CEPPA as the main raw materials, and adopt an intermittent 4-reactor process: first esterification, second esterification, pre-polycondensation, and final polycondensation to obtain the copolymer flame-retardant ECDP polyester chips.

[0009] Although this patent can realize the production of flame-retardant ECDP polyester chips, it adopts an intermittent four-reactor process, and the product is flame-retardant ECDP, which does not solve the problem of industrial continuous large-scale production. At the same time, the products, equipment, catalysts, additives and types are also quite different from the present invention.

[0010] In the document “Preparation of Cationic Dyeable Copolyesters and Study on Their Structural Properties (Doctoral Dissertation, Tianjin Polytechnic University, 2008)”, relevant research on the synthesis of cationic dyeable copolyesters was also conducted. First, ether-type and ester-type fourth monomer modifiers of different structures were synthesized, and the optimal process conditions were found. Then, on the basis of terephthalic acid (PTA) and ethylene glycol (EG), the third monomer sodium dihydroxyethyl isophthalate-5-sulfonate (SIPE) and various synthesized fourth monomer modifiers were added to carry out copolymerization reactions to obtain conventional PET, CDP, ether-type and ester-type ECDP copolyesters, respectively.

[0011] In the document “Development of Production Technology of Cationic Dye-Easy-Dyeing Polyester (Master’s Thesis, Dalian University of Technology, 2006)”, the process of developing the production technology of cationic dye-easy-dyeing polyester is carried out by using DMT (dimethyl terephthalate) and EG (ethylene glycol) as the main raw materials, manganese acetate as the ester exchange catalyst, and antimony trioxide as the polycondensation catalyst, and adding appropriate amounts of the third and fourth monomers.

[0012] In the journal article "Research on Thermal Properties of Cationic Easily Dyeable Copolyesters (Synthetic Fiber Industry, January 2011)", a cationic easily dyeable copolyester (ECDP) containing the third monomer sodium isophthalate-5-sulfonate (SIPE) and the fourth monomer polyethylene glycol (PEG) was synthesized on a semi-continuous large-scale device; the thermal properties of ECDP were studied by thermogravimetric analysis and differential scanning calorimetry, and the intrinsic viscosity drop of ECDP slices during drying and melting was tested. The results show that: with the increase of PEG content, the thermal decomposition temperature of ECDP decreases, the glass transition temperature decreases accordingly, while the cold crystallization temperature and melting point are affected by SIPE and PEG; with the increase of PEG content, the influence of ECDP melt residence time on the melt intrinsic viscosity drop increases; ECDP with high PEG content should choose a relatively low drying temperature and a longer residence time to ensure the quality of dried slices.

[0013] The above three documents are mainly experimental studies and cannot break through the difficulties of industrial continuous large-scale production.

[0014] Although there are a large number of companies at home and abroad that can produce ECDP, their production mode is still mainly intermittent small-batch production, and the problem of industrial continuous large-scale production has not been effectively broken through. The main shortcomings are easy self-polymerization of monomers, easy clogging of the system, poor overall quality, unstable dyeing performance between batches, poor product spinnability and thermal stability, etc. In fact, few domestic manufacturers have fully mastered the core technology of industrial continuous production of ECDP.

[0015] Therefore, accelerating the development of the ECDP industry and breaking through the bottleneck of industrial continuous large-scale production have important economic and strategic value for promoting the structural adjustment and upgrading of my country's polyester industry and supply-side structural reform and replacing imported products. Summary of the invention

[0016] The purpose of the present invention is to provide an industrialized continuous manufacturing method for normal pressure cationic easy-to-dye polyester chips. The present invention conducts production research on a 50,000-ton / year five-reactor process, adopts a unique process formula and process package, and distributes the degree of polymerization of each reactor in stages, so that the reaction conditions are milder, which can solve the problems faced by the industrialized continuous large-scale production of normal pressure cationic easy-to-dye polyester, such as easy self-polymerization of monomers, easy clogging of the system, poor overall quality, and unstable dyeing performance between batches. The produced normal pressure cationic easy-to-dye polyester chips have the advantages of stable product quality, strong dyeing performance, good uniformity, good spinnability, and good thermal stability. It can provide new polyester products that are easy to dye and environmentally friendly for subsequent printing and dyeing, and adapt to the market demand of the increasingly stringent environmental protection situation in the new era.

[0017] The technical solution of the present invention is as follows:

[0018] The present invention provides an industrialized continuous manufacturing method of normal pressure cationic easy-dyeing polyester chips, comprising:

[0019] (1) stirring terephthalic acid (PTA), ethylene glycol (EG), and a titanium catalyst ethylene glycol solution to form a slurry; wherein the molar ratio of terephthalic acid (PTA) to ethylene glycol (EG) is controlled to be 1: (0.8-1.6);

[0020] (2) injecting the slurry prepared in step (1) into a first esterification reaction kettle, carrying out the first esterification reaction at a temperature of 250 to 280° C. and a gauge pressure of 0.04 to 0.12 MPa, controlling the reaction residence time to be 1.0 to 3.0 h or terminating the reaction when the esterification rate of the first esterification product reaches 90% or above, to obtain a first esterification product;

[0021] (3) After the first esterification product enters the second esterification kettle, the third monomer, the fourth monomer and the anti-ether agent are injected at low temperature, and the esterification reaction is further carried out under the reaction conditions of a gauge pressure of 0.01 to 0.08 MPa and a temperature of 220 to 260° C., and the reaction residence time is controlled to be 0.8 to 2.2 hours or the reaction is terminated when the esterification rate reaches 94% or above, to obtain a second esterification product; wherein the third monomer accounts for 1.5 to 5.0 wt% in the finally obtained ECDP polyester chips; and the addition amount of the fourth monomer accounts for 0.5 to 4.0 wt% in the finally obtained ECDP polyester chips;

[0022] (4) mixing a titanium-based catalyst ethylene glycol solution, an antimony-based catalyst ethylene glycol solution, and a heat stabilizer with the second esterification product to obtain a prepolymerization reaction material, injecting the prepolymerization reaction material into a first prepolymerization reaction kettle, and conducting a first polycondensation reaction under the reaction conditions of an absolute pressure of 600 to 3000 Pa and a temperature of 260 to 285° C., controlling the reaction residence time to 0.5 to 1.5 h, to obtain a first prepolymer with an intrinsic viscosity of 0.15 to 0.45 dl / g;

[0023] (5) After the first prepolymer enters the second prepolymerization reactor, a second prepolymerization reaction is carried out under the reaction conditions of an absolute pressure of 50 to 1000 Pa and a temperature of 265 to 285° C., and the reaction residence time is controlled to be 0.5 to 1.5 h to obtain a second prepolymer with an intrinsic viscosity of 0.3 to 0.6 dl / g;

[0024] (6) After the second prepolymer enters the final polycondensation reaction kettle, a final polycondensation reaction is carried out under the reaction conditions of an absolute pressure of 10 to 500 Pa and a temperature of 255 to 285° C., and the reaction residence time is controlled to be 0.5 to 1.5 h to obtain a final polycondensation melt with an intrinsic viscosity of 0.45 to 0.75 dl / g;

[0025] (7) Pelletizing system: The final polymerized melt is subjected to belt casting, water cooling, underwater pelletizing and drying processes to obtain ECDP polyester chips.

[0026] Furthermore, the titanium-based catalyst in step (1) is tetrabutyl titanate, tetraisopropyl titanate or titanium ethylene glycol.

[0027] The concentration of the titanium catalyst ethylene glycol solution in step (1) is 1 to 6 wt %; the content of titanium atoms in the slurry is 0.01 to 1.5 ppm.

[0028] Furthermore, the first esterification kettle in step (2) adopts vertical stirring to ensure that the reaction materials are fully mixed and uniform.

[0029] Furthermore, the third monomer in step (3) is injected in the form of a stock solution, and the third monomer stock solution is a stock solution of bis(hydroxyethyl)isophthalate-5-sulfonate; wherein the concentration of bis(hydroxyethyl)isophthalate-5-sulfonate is 30-50wt%.

[0030] Furthermore, the third monomer is bis(hydroxyethyl)isophthalate-5-sulfonate; specifically, it can be sodium bis(hydroxyethyl)isophthalate-5-sulfonate, potassium bis(hydroxyethyl)isophthalate-5-sulfonate or lithium bis(hydroxyethyl)isophthalate-5-sulfonate, etc. The preferred third monomer is sodium bis(hydroxyethyl)isophthalate-5-sulfonate.

[0031] Furthermore, the fourth monomer in step (3) is a polyether compound; specifically, it may be polyethylene glycol with a molecular weight distribution range of 500 to 5000.

[0032] Furthermore, the anti-etherification agent in step (3) is an acetate, which can be sodium acetate or potassium acetate, etc. The anti-etherification agent is used to help control the degree of etherification side reactions, control the DEG content in the product, and improve the spinning performance of the product; the addition amount is 5 to 120 ppm.

[0033] Furthermore, the second esterification kettle in step (3) adopts vertical stirring to ensure that the reaction materials are fully mixed and uniform.

[0034] Furthermore, the concentration of the antimony-based catalyst ethylene glycol solution in the step (4) is 2 to 8 wt%, and the content of antimony atoms in the prepolymerization reaction material is 1 to 100 ppm; the concentration of the titanium-based catalyst ethylene glycol solution is 1 to 6 wt%, and the content of titanium atoms in the prepolymerization reaction material is 0.02 to 3.0 ppm; the thermal stabilizer is a phosphorus compound thermal stabilizer, and the amount of the thermal stabilizer added to the prepolymerization reaction material is 0.5 to 30 ppm.

[0035] Furthermore, the antimony catalyst in step (4) is antimony glycol, antimony trioxide or antimony triacetate.

[0036] Furthermore, the titanium-based catalyst in step (4) is tetrabutyl titanate, tetraisopropyl titanate or titanium ethylene glycol.

[0037] Furthermore, the heat stabilizer in step (4) is phosphoric acid, trimethyl phosphate or phosphorous acid.

[0038] Furthermore, the first prepolymerization kettle in step (4) adopts vertical stirring to ensure that the reaction materials are fully mixed and uniform.

[0039] Furthermore, the second prepolymerization kettle in step (5) is stirred by horizontal disc-shaped blades to ensure that the reaction materials are fully mixed and uniform.

[0040] Furthermore, the final polycondensation reactor in step (6) is stirred by horizontal disc-shaped blades to ensure that the reaction materials are fully mixed and uniform.

[0041] Furthermore, the final polymerized melt in step (6) is filtered through a melt filter to remove impurities and then enters a subsequent pelletizing system.

[0042] The present invention also provides a normal pressure cationic easy-dyeing polyester chip obtained by the above manufacturing method.

[0043] Furthermore, the normal pressure cationic easy-to-dye polyester chips have a melting point range of 230° C. to 265° C., a diethylene glycol content of less than 2.0 wt %, and an intrinsic viscosity of 0.45 to 0.75 dl / g.

[0044] The invention prepares slurry by mixing ethylene glycol solution containing titanium catalyst, terephthalic acid (PTA) and ethylene glycol (EG); after the first step of esterification reaction, the slurry is mixed with the third and fourth monomers and an anti-ether agent to carry out the second step of esterification reaction; the esterified oligomer is mixed with ethylene glycol containing titanium and antimony catalysts, a heat stabilizer and the like, and then two steps of prepolymerization reaction and one step of final polymerization reaction are carried out, and finally the ECDP polyester chips are obtained by pelletizing.

[0045] The beneficial effects of the present invention are:

[0046] The present invention adopts a unique process formula and process package, which can be used for industrialized continuous mass production of ECDP in a 50,000-ton five-reactor process, breaking through the bottleneck of industrialized continuous mass production, and achieving stable quality and good uniformity between batches of products. At the same time, the process solves the problem of easy self-polymerization of monomers such as the third monomer and easy blockage of the reaction system in the ECDP production process.

[0047] The manufacturing method of the present invention uses fewer types of additives with lower content, and adopts a composite catalyst, which can reduce the use of antimony catalysts, making the product cleaner and more stable in performance.

[0048] In the manufacturing method of the present invention, the catalyst is added in a combination of pre-addition and post-addition, and the residence time and reaction temperature of each reactor are controlled to achieve a stepwise distribution of the reaction polymerization degrees of the five reactors, so that the reaction conditions are milder, thereby controlling the reaction degree and the reaction stability, making the reaction system more adaptable to PTA raw materials of different qualities, and the performance indicators of the product such as DEG content are more stable, and the spinnability and thermal stability are good;

[0049] In addition, by adjusting the ratio of different monomers, the content of additives and the reaction conditions, high-quality ECDP polyester chips with a melting point range of 230°C to 265°C, a diethylene glycol content of less than 2.0wt%, an intrinsic viscosity of 0.45 to 0.75dl / g and a high coloring rate can be produced on a single production line. DETAILED DESCRIPTION

[0050] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, some adjustments and improvements can also be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0051] Examples 1-9

[0052] (1) PTA, EG, and titanium catalyst ethylene glycol solution are mixed and stirred to form a slurry;

[0053] (2) injecting the slurry prepared in step (1) into a first esterification reaction kettle, controlling the temperature, gauge pressure and reaction time, and performing the first esterification reaction to obtain a first esterified product;

[0054] (3) After the first esterification product enters the second esterification reactor, the prepared third monomer (sodium bis(hydroxyethyl)isophthalate-5-sulfonate), fourth monomer (polyethylene glycol with a molecular weight of 3000) and anti-ether agent (sodium acetate) are injected, and the temperature, gauge pressure and reaction time are controlled to carry out the second step esterification reaction to obtain the second esterification product;

[0055] (4) mixing the antimony-based catalyst ethylene glycol solution, the titanium-based catalyst ethylene glycol solution and trimethyl phosphate with the second esterification product to obtain a prepolymerization reaction material, injecting the prepolymerization reaction material into a first prepolymerization reaction kettle, controlling the pressure, temperature and reaction time, and performing a first polycondensation reaction to obtain a first prepolymer;

[0056] (5) After the first prepolymer enters the second prepolymerization reactor, the pressure, temperature and reaction time are controlled to carry out a second prepolymerization reaction to obtain a second prepolymer;

[0057] (6) After the second prepolymer enters the final polycondensation reactor, the pressure, temperature and reaction time are controlled to obtain a final polycondensation melt;

[0058] (7) Pelletizing system: The final polymerized melt is subjected to belt casting, water cooling, underwater pelletizing and drying processes to obtain ECDP polyester chips.

[0059] The reaction raw material ratios of the above Examples 1-9 are shown in Table 1.

[0060] The reaction conditions and parameters of the first and second esterification reaction kettles of the above Examples 1-9 are shown in Table 2.

[0061] The dosage ratios of the third monomer, the fourth monomer and the ether-proofing agent in the above-mentioned Examples 1-9 are shown in Table 3.

[0062] The reaction conditions and parameters of the first prepolymerization reactor of Examples 1-9 are shown in Table 4.

[0063] The catalysts used in the first prepolymerization reactor of the above Examples 1-9 are shown in Table 5.

[0064] The reaction conditions and parameters of the second prepolymerization reactor and the final polycondensation reactor of the above Examples 1-9 are shown in Table 6.

[0065] The performance data of the final melt and ECDP polyester chips obtained in the above Examples 1-9 are shown in Table 7.

[0066] Table 1 Raw material ratio table

[0067]

[0068]

[0069] Table 2 Reaction conditions and parameters of the first and second esterification reactors

[0070]

[0071] Table 3 Dosage ratio of the third monomer, the fourth monomer and the ether-proofing agent

[0072]

[0073] Table 4 Reaction conditions and parameters of the first prepolymerization reactor

[0074]

[0075]

[0076] Table 5 Catalyst used in the first prepolymerization reactor

[0077] Example Antimony catalyst Titanium Catalysts Example 1 Antimony glycolate Tetrabutyl titanate Example 2 Antimony trioxide + antimony glycol Tetraisopropyl titanate Example 3 Antimony triacetate Titanium glycolate Example 4 Antimony glycol + antimony trioxide Tetrabutyl titanate + tetraisopropyl titanate Example 5 Antimony trioxide + antimony triacetate Tetraisopropyl titanate + tetrabutyl titanate + ethylene glycol titanium Example 6 Antimony triacetate + antimony glycol Titanium glycolate Example 7 Antimony glycol + antimony trioxide + antimony triacetate Tetrabutyl titanate + ethylene glycol titanium Example 8 Antimony trioxide + antimony glycol Tetraisopropyl titanate + ethylene glycol titanium Example 9 Antimony triacetate + antimony glycol Titanium glycolate

[0078] Table 6 Reaction conditions and parameters of the second prepolymerization reactor and the final polycondensation reactor

[0079]

[0080] Table 7 Performance data of final melt and ECDP polyester chips

[0081]

[0082] The preferred embodiments of the present invention have been specifically described above, but the present invention is not limited to the described embodiments. Those skilled in the art may make various equivalent modifications or substitutions without violating the spirit of the present invention. These equivalent modifications or substitutions are all included in the scope defined by the claims of this application.

Claims

1. An industrialized continuous production method of normal pressure cationic easy-dyeing polyester chips, comprising: (1) stirring terephthalic acid (PTA), ethylene glycol (EG), and a titanium-based catalyst ethylene glycol solution to form a slurry; wherein the molar ratio of terephthalic acid (PTA) to ethylene glycol (EG) is controlled at 1: (0.8-1.6); the concentration of the titanium-based catalyst ethylene glycol solution is 1-6 wt %; and the content of titanium atoms in the slurry is 0.01-1.5 ppm; (2) injecting the slurry prepared in step (1) into the first esterification reaction kettle, carrying out the first esterification reaction at a temperature of 250 to 280° C. and a gauge pressure of 0.04 to 0.12 MPa, controlling the reaction residence time to be 1.0 to 3.0 h or terminating the reaction when the esterification rate of the first esterification product reaches 90% or above, to obtain the first esterification product; (3) After the first esterification product enters the second esterification reactor, the third monomer, the fourth monomer and the anti-ether agent are injected at low temperature, and the esterification reaction is further carried out under the reaction conditions of a gauge pressure of 0.01 to 0.08 MPa and a temperature of 220 to 260° C. The reaction residence time is controlled to be 0.8 to 2.2 h or the reaction is terminated when the esterification rate reaches 94% or above to obtain a second esterification product; wherein the third monomer accounts for 1.5 to 5.0 wt% of the final ECDP polyester chips; and the addition amount of the fourth monomer accounts for 0.5 to 4.0 wt% of the final ECDP polyester chips; (4) A titanium catalyst ethylene glycol solution, an antimony catalyst ethylene glycol solution, a heat stabilizer, and the second esterification product are mixed to obtain a prepolymerization reaction material, the prepolymerization reaction material is injected into a first prepolymerization reaction kettle, and a first polycondensation reaction is carried out under the reaction conditions of an absolute pressure of 600 to 3000 Pa and a temperature of 260 to 285° C., the reaction residence time is controlled to be 0.5 to 1.5 h, and a first prepolymer with an intrinsic viscosity of 0.15 to 0.45 dl / g is obtained; wherein the concentration of the antimony catalyst ethylene glycol solution is 2 to 8 wt %, and the content of antimony atoms in the prepolymerization reaction material is 1 to 100 ppm; the concentration of the titanium catalyst ethylene glycol solution is 1 to 6 wt %, and the content of titanium atoms in the prepolymerization reaction material is 0.02 to 3.0 ppm; (5) After the first prepolymer enters the second prepolymerization reactor, a second prepolymerization reaction is carried out under the reaction conditions of an absolute pressure of 50 to 1000 Pa and a temperature of 265 to 285° C., and the reaction residence time is controlled to be 0.5 to 1.5 h to obtain a second prepolymer with an intrinsic viscosity of 0.3 to 0.6 dl / g; (6) After the second prepolymer enters the final polycondensation reaction kettle, a final polycondensation reaction is carried out under the reaction conditions of an absolute pressure of 10 to 500 Pa and a temperature of 255 to 285° C., and the reaction residence time is controlled to be 0.5 to 1.5 h to obtain a final polycondensation melt with an intrinsic viscosity of 0.45 to 0.75 dl / g; (7) Pelletizing system: The final polymerized melt is subjected to belt casting, water cooling, underwater pelletizing and drying processes to obtain ECDP polyester chips.

2. The industrialized continuous production method of a normal pressure cationic easy-dyeing polyester chip according to claim 1, characterized in that: The titanium-based catalyst in step (1) is tetrabutyl titanate, tetraisopropyl titanate or ethylene glycol titanium.

3. The industrialized continuous production method of normal pressure cationic easy-dyeing polyester chips according to claim 1 is characterized in that: The third monomer in step (3) is injected in the form of a stock solution, and the third monomer stock solution is a stock solution of bis(hydroxyethyl)isophthalate-5-sulfonate; wherein the concentration of bis(hydroxyethyl)isophthalate-5-sulfonate is 30-50 wt%.

4. The industrialized continuous production method of normal pressure cationic easy-dyeing polyester chips according to claim 1 is characterized in that: The third monomer is dihydroxyethyl isophthalate-5-sulfonate; the fourth monomer is polyethylene glycol with a molecular weight distribution range of 500-5000.

5. The industrialized continuous production method of normal pressure cationic easy-dyeing polyester chips according to claim 1 is characterized in that: The heat stabilizer in step (4) is a phosphorus compound heat stabilizer, and the amount of the heat stabilizer added to the prepolymerization reaction material is 0.5 to 30 ppm.

6. The industrialized continuous production method of normal pressure cationic easy-dyeing polyester chips according to claim 1 is characterized in that: The antimony catalyst in step (4) is antimony glycolate, antimony trioxide or antimony triacetate; the titanium catalyst is tetrabutyl titanate, tetraisopropyl titanate or titanium glycolate.

7. A normal pressure cationic easy-dyeing polyester chip produced by the production method according to any one of claims 1 to 6.

8. The normal pressure cationic easy-dyeing polyester chip according to claim 7, characterized in that: The normal pressure cationic easy-dyeing polyester chips have a melting point range of 230° C. to 265° C., a diethylene glycol content of less than 2.0 wt%, and an intrinsic viscosity of 0.45 to 0.75 dl / g.

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