Production system and method of multi-copolymerized petg

Abstract

This invention discloses a production system and method for multi-component copolymerized PETG. The top of the slurry preparation tank is connected to feed pipes for PTA, EG, and additives. The bottom outlets of the pre-melting reactors for CHDM and NPG are respectively connected to intermediate tanks. The bottom outlets of the two intermediate tanks are connected to the top inlet of the slurry preparation tank via transfer pumps. The outlet of the slurry preparation tank is connected to the inlet of the first esterification reactor via a slurry transfer pump. The bottom outlet of the first esterification reactor is connected to the inlet of the second esterification reactor. The outlet of the second esterification reactor is connected to the inlet of the pre-condensation reactor, the outlet of the pre-condensation reactor is connected to the inlet of the second condensation reactor, and the outlet of the second condensation reactor is connected to the inlet of the final condensation reactor. The production method sequentially includes the following steps: preparing a quaternary slurry of PTA, EG, CHDM, and NPG in a molar ratio; esterification reaction; pre-condensation reaction; condensation reaction; and final condensation reaction. This invention has low raw material costs and produces PETG products with good performance.

Description

Technical Field

[0001] This invention relates to the preparation of a polymer material, and more particularly to a production system for multi-component copolymer PETG. This invention also relates to a production method for multi-component copolymer PETG, belonging to the field of polyester material manufacturing technology. Background Technology

[0002] PETG is a transparent plastic, an amorphous copolyester, officially named polyethylene terephthalate-1,4-cyclohexanediethanol ester. The commonly used comonomer for PETG is 1,4-cyclohexanediethanol (CHDM). Current PETG technology involves the direct esterification and subsequent polycondensation of terephthalic acid (PTA), ethylene glycol (EG), and 1,4-cyclohexanediethanol (CHDM). PETG sheets offer advantages such as high light transmittance, high gloss, good chemical resistance, high impact strength, and environmental friendliness. They are widely used in advertising, machinery, food, and packaging industries, and can be used to make medical equipment, advertising signs, high-transparency price tags, machine covers, baffles, observation windows, picture frames, etc.

[0003] In the existing technology, most PETG production uses terephthalic acid, 1,4-cyclohexanediethanol (CHDM), and ethylene glycol ternary monomers as raw materials.

[0004] Chinese invention patent CN 102558517B discloses an eco-friendly multifunctional ternary copolymer PETG polyester, its preparation method, and a method for preparing a uniaxially stretched heat-shrinkable film from the polyester. It is copolymerized from terephthalic acid, neopentyl glycol, and ethylene glycol, with a molar ratio of terephthalic acid, neopentyl glycol, and ethylene glycol of 1:(0.1–0.65):(1.2–1.75). The preparation method includes esterification and polymerization reactions. The esterification reaction is carried out at a temperature of 200℃–255℃, the polymerization reaction at a temperature of 270℃–280℃, and the vacuum degree of the polymerization reaction is 0.098MPa–0.1MPa.

[0005] The existing technology for preparing PETG has the following problems: 1. It uses three monomers, terephthalic acid (PTA), ethylene glycol (EG) and 1,4-cyclohexanediethanol (CHDM), as raw materials. Due to the high price of 1,4-cyclohexanediethanol (CHDM), the product cost is very high. Moreover, the supply of raw materials has long been restricted by foreign suppliers, which restricts the application scope and cost-effectiveness and inhibits the development of the industry.

[0006] 2. The Chinese invention patent with publication number CN 102558517B uses terephthalic acid, neopentyl glycol (NPG), and ethylene glycol ternary monomers as raw materials. Neopentyl glycol (NPG) is inexpensive and can produce PETG products, but the products have poor transparency and toughness, and the product quality varies, making it difficult to meet the application needs of high-end fields such as high temperature resistance, baby products, and medical applications.

[0007] 3. Chinese invention patent application with publication number CN 110684184A uses a single antimony or titanium as a catalyst in the production process, resulting in poor product color and high catalyst consumption.

[0008] 4. Chinese invention patent application with publication number CN 111484607A uses cobalt acetate as a colorant in the production process, which introduces the heavy metal cobalt into the product, which is detrimental to health and the environment.

[0009] 5. High energy consumption during the production process increases production costs. Summary of the Invention

[0010] The primary objective of this invention is to overcome the problems existing in the prior art and provide a production system for multi-component copolymerized PETG that meets the requirements of direct esterification and polycondensation of quaternary monomers. This system can reduce raw material costs and produce PETG products with high elongation at break, high transparency, high gloss, impact resistance, and chemical resistance.

[0011] To address the above technical problems, the present invention provides a multi-component copolymer PETG production system, comprising a slurry preparation tank, a CHDM premelting kettle, and an NPG premelting kettle. The top of the slurry preparation tank is connected to a PTA feed pipe, an EG feed pipe, and an additive feed pipe. The outlet of the slurry preparation tank is connected to the inlet of an esterification reactor I via a slurry transfer pump. The bottom outlet of the CHDM premelting kettle is connected to the top inlet of a CHDM intermediate tank, and the bottom outlet of the CHDM intermediate tank is connected to the CHDM feed pipe via a CHDM transfer pump. The bottom outlet of the NPG premelting kettle is connected to the top inlet of the NPG intermediate tank, and the bottom outlet of the NPG intermediate tank is connected to the NPG feed pipe via an NPG transfer pump. The CHDM feed pipe and the NPG feed pipe are respectively connected to the top inlet of the slurry preparation tank via flow meters and regulating valves. The bottom outlet of the esterification reactor I is connected to the inlet of an esterification reactor II.

[0012] As an improvement of the present invention, the outlet of the esterification reactor is connected to the inlet of the prepolymerization reactor, the outlet of the prepolymerization reactor is connected to the inlet of the polycondensation reactor, and the outlet of the polycondensation reactor is connected to the inlet of the final polycondensation reactor.

[0013] As a further improvement of the present invention, the top exhaust ports of the first esterification reactor and the second esterification reactor are respectively connected to the lower inlet of the process tower, the bottom outlet of the process tower is connected to the inlet of the bottom transfer pump, the outlet of the bottom transfer pump is connected to the EG reflux pipe of the esterification reactor and the ethylene glycol recycling tank, and the outlet of the EG reflux pipe of the esterification reactor is respectively connected to the top reflux port of the first esterification reactor and the second esterification reactor.

[0014] As a further improvement of the present invention, the outlet of the bottom delivery pump is also connected to the inlet of the heat medium heating pipe through the heated EG pipe, the outlet of the heat medium heating pipe is connected to the inlet of the heating coil of the CHDM premelting kettle and the NPG premelting kettle respectively, and the outlet of the heating coil of the CHDM premelting kettle and the NPG premelting kettle is connected to the reflux EG pipe of the process tower.

[0015] As a further improvement of the present invention, the top outlet of the process tower is connected to the top tail gas output pipe and the top tail gas heating pipe, and the outlet of the top tail gas heating pipe is also connected to the inlet of the heat medium heating pipe; the heating coil outlets of the CHDM premelting kettle and the NPG premelting kettle are also connected to the condensate discharge pipe.

[0016] As a further improvement of the present invention, the outlet of the heat medium heating pipe is connected to the heating jacket inlet of the CHDM premelting kettle, CHDM intermediate tank, NPG premelting kettle, NPG intermediate tank and slurry preparation tank respectively, and the heating jacket outlet of the CHDM premelting kettle, CHDM intermediate tank, NPG premelting kettle, NPG intermediate tank and slurry preparation tank is connected to the process tower reflux EG pipe and condensate discharge pipe respectively through a three-way valve.

[0017] As a further improvement of the present invention, the bottom of the esterification reactor, the top of the esterification reactor, and the bottom of the prepolymerization reactor are respectively connected to the auxiliary agent feed pipe, and the inlet of the auxiliary agent feed pipe is connected to the catalyst feed pipe and the stabilizer feed pipe respectively.

[0018] As a further improvement of the present invention, the polycondensation reactor includes a horizontal cylindrical body, with a stirring shaft arranged along the axis of the inner cavity of the cylinder. One end of the stirring shaft passes through the center of the end cover and is supported in the end cover sealing seat by a bearing. A sealing liquid sealing section and a lubricating oil sealing section are arranged from the inside to the outside between the inner cavity of the end cover sealing seat and the stirring shaft. The outer end of the stirring shaft is connected to the output shaft of the reducer. The feature is that: an auxiliary oil tank is fixed on the housing of the reducer, and a cooling coil is arranged in the inner cavity of the auxiliary oil tank; a shaft end pump is installed at the shaft end of the input shaft of the reducer, the inlet of the shaft end pump is connected to the oil outlet of the auxiliary oil tank, the outlet of the shaft end pump is connected to the oil inlet of the lubricating oil sealing section, and the oil outlet of the lubricating oil sealing section is connected to the oil return port of the auxiliary oil tank; the liquid inlet of the sealing liquid sealing section is connected to the sealing EG supply pipe, and the liquid outlet of the sealing liquid sealing section is connected to the EG recycling system through the sealing EG recovery pipe.

[0019] As a further improvement of the present invention, the final polycondensation reactor includes a horizontal cylindrical body. A rotor shaft is axially mounted in the inner cavity of the cylindrical body. Multiple parallel annular disks are fixed along the axial direction of the rotor shaft. Multiple rotating scrapers extending beyond the outer edge of the annular disk are uniformly provided on each annular disk. The rotating scrapers extend along the axial direction of the cylindrical body and the blades point towards the inner wall of the cylindrical body. Baffles are provided between adjacent annular disks. The bottom of each baffle is fixed to the inner wall of the cylindrical body. A disc scraper is fixed to the upper edge of each baffle. The blades on both sides of the disc scraper point towards the side wall of the adjacent annular disk.

[0020] As a further improvement of the present invention, a rotating shaft scraper is fixed at the upper center of each baffle, and each rotating shaft scraper extends along the axial direction of the cylinder with the blade pointing towards the outer periphery of the rotor shaft; a thickened baffle beam is provided at the upper edge of each baffle, and the root of each disc scraper and rotating shaft scraper is welded to the corresponding baffle beam.

[0021] Another objective of this invention is to overcome the problems existing in the prior art and provide a method for producing multi-component copolymerized PETG that meets the requirements of direct esterification and polycondensation of quaternary monomers. This method can reduce raw material costs and produce PETG products with high elongation at break, high transparency, high gloss, impact resistance, and chemical resistance.

[0022] To solve the above technical problems, the present invention provides a method for producing multi-component copolymerized PETG, comprising the following steps in sequence:

[0023] S1. Slurry preparation: Terephthalic acid, ethylene glycol, 1,4-cyclohexanediol, neopentyl glycol, catalyst, stabilizer and colorant are added to the slurry preparation tank in a certain proportion and mixed thoroughly.

[0024] S2, Esterification reaction: The slurry in the slurry preparation tank is transported to the first esterification reactor by the slurry transfer pump for esterification reaction. The esterified material in the first esterification reactor enters the second esterification reactor under the action of position difference and pressure difference for further esterification reaction.

[0025] S3. Prepolymerization reaction: The esterified material in the esterification reactor enters the prepolymerization reactor under the action of position difference and pressure difference to carry out the prepolymerization reaction and obtain the prepolymer.

[0026] S4. Polycondensation reaction: The prepolymer in the prepolymerization reactor enters the second polycondensation reactor under the action of position difference and pressure difference, and further undergoes the polycondensation reaction.

[0027] S5. Final polycondensation reaction: The prepolymer in the second polycondensation reactor is pumped into the final polycondensation reactor by the prepolymer transfer pump to further carry out the polycondensation reaction and obtain PETG melt.

[0028] As an improvement of the present invention, the molar ratio of the quaternary monomers is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediol: neopentyl glycol = 1: (0.5-0.9): (0.2-0.5): (0.15-0.7); the catalyst is a composite catalyst composed of tetrabutyl titanate, antimony acetate and ethyl silicate, wherein the amount of tetrabutyl titanate relative to terephthalic acid is 40-100 ppm, the amount of antimony acetate relative to terephthalic acid is 9-23 ppm, and the amount of ethyl silicate relative to terephthalic acid is 4.5-11 ppm.

[0029] As a further improvement of the present invention, the stabilizer is triphenyl phosphite or triethyl phosphite, wherein the amount of triphenyl phosphite added relative to terephthalic acid is 30-68 ppm, and the amount of triethyl phosphite added relative to terephthalic acid is 28-41 ppm; the colorant is red or blue pigment, and the amount added relative to terephthalic acid is 0.5-2 ppm.

[0030] As a further improvement of the present invention, the molar ratio of the quaternary monomers is as follows: phthalic acid: ethylene glycol: 1,4-cyclohexanediethanol: neopentyl glycol = 1:0.7:0.4:0.2; the intrinsic viscosity IV value of the product is ≥0.8 dl / g, the color value L value is ≥87, the color value b value is ≤2.1, the elongation at break is ≥220%, the yield strength is ≥48MPa, and the tensile modulus of elasticity is ≥920MPa.

[0031] As a further improvement of the present invention, the 1,4-cyclohexanediethanol and neopentyl glycol are melted in separate pre-melting kettles, and after melting, they are discharged to the corresponding finished product tanks and continuously added to the slurry preparation tank after being metered by a flow meter.

[0032] As a further improvement of the present invention, the reaction pressure in the first esterification reactor is 100-300 kPa, the reaction temperature is 185-240°C, and the residence time is 2.0-4 h; the reaction pressure in the second esterification reactor is 5-50 kPa, the reaction temperature is 241-245°C, and the residence time is 1.0-2 h; the reaction pressure in the prepolymerization reactor is 5-20 kPa, the reaction temperature is 246-258°C, and the residence time is 0.5-1 h; the reaction pressure in the second polymerization reactor is 0.5-2 kPa, the reaction temperature is 259-268°C, and the residence time is 1-2 h; and the reaction pressure in the final polymerization reactor is 50-400 kPa, the reaction temperature is 269-278°C, and the residence time is 2-3 h.

[0033] As a further improvement of the present invention, catalysts are added from the bottom of the first esterification reactor and the prepolymerization reactor respectively; the mixed vapors generated by the first esterification reactor and the second esterification reactor are sent to the bottom of the process tower for distillation and separation; the ethylene glycol at the bottom of the process tower is pumped out and divided into three paths; the first path is metered by a flow meter and added to the first esterification reactor and the second esterification reactor respectively; the second path is sent to the ethylene glycol recycling tank; and the third path is sent to the jacket or coil of the CHDM premelting reactor, NPG premelting reactor, CHDM intermediate tank, NPG intermediate tank and slurry preparation tank as a heat source.

[0034] As a further improvement of the present invention, the water vapor discharged from the top of the process tower is used as a heat source for the jacket or coil of the CHDM premelting kettle, NPG premelting kettle, CHDM intermediate tank, NPG intermediate tank and slurry preparation tank, or as a heat source for the refrigeration unit, or as a power source for the steam turbine to generate electricity.

[0035] Compared with the prior art, the present invention has achieved the following beneficial effects: 1. Using terephthalic acid, ethylene glycol, 1,4-cyclohexanediol and neopentyl glycol as quaternary monomers as raw materials, the raw material ratio is optimized, which not only reduces the raw material cost, but also produces PETG products that meet the requirements of high elongation at break, high transparency, gloss, impact resistance and chemical resistance.

[0036] 2. Using titanium, antimony, and silicon as a composite catalyst not only improves the catalytic reaction activity but also solves the problem of poor color.

[0037] 3. Triphenyl phosphate is used as a stabilizer, and red and blue pigments are used as colorants. The heavy metal cobalt is not used as a colorant, which avoids environmental pollution and makes the product healthier and more environmentally friendly.

[0038] 4. The heating is achieved by using high-temperature EG at the bottom of the process tower or water vapor at the top of the process tower, and the melting temperature of the raw materials is precisely controlled by a temperature regulating valve, which solves the heating problem and reduces energy consumption. Attached Figure Description

[0039] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The drawings are provided for reference and illustration only and are not intended to limit the present invention.

[0040] Figure 1 This is a flowchart of the production system for multi-component copolymerized PETG of the present invention;

[0041] Figure 2 This is a front view of the polycondensation reactor in this invention;

[0042] Figure 3 This is a top view of the polycondensation reactor in this invention;

[0043] Figure 4 This is a front view of the final polycondensation reactor in this invention;

[0044] Figure 5 This is a cross-sectional view of the final polycondensation reactor in this invention;

[0045] Figure 6 This is a schematic diagram of the baffle in the final polycondensation reactor.

[0046] Figure 7 for Figure 6 Enlarged sectional view along the middle AA line;

[0047] In the diagram: 1. CHDM premelting kettle; 2. CHDM intermediate tank; 3. NPG premelting kettle; 4. NPG intermediate tank; 5. Slurry preparation tank; 6. Esterification kettle 1; 7. Esterification kettle 2; 8. Prepolymerization kettle; 9. Polycondensation kettle 2; 9a. Shell; 9b. End cap; 9c. End cap sealing seat; c1. Sealing liquid inlet; c2. Sealing liquid outlet; c3. Lubricating oil inlet; c4. Lubricating oil outlet; 9d. Stirring shaft; 9e. Reducer; 9f. Shaft-end pump; 9g. Auxiliary... Oil tank; 9h. Torque arm; 10. Final polycondensation reactor; 10a. Cylinder; 10a1. Gas phase outlet; 10a2. Melt outlet; 10a3. Heating jacket; 10b. Rotor shaft; 10c. Annular disc; 10d. Baffle; 10d1. Baffle beam; 10d2. Baffle flow groove; 10d3. Baffle fixing point; 10e. Rotary shaft scraper; 10f. Spoke; 10g. Rotary scraper; 10h. Disc scraper; 11. Pelletizer; 12. Downstream user; 13. Process Tower; 14. Ethylene glycol recycling tank; B1. CHDM transfer pump; B2. NPG transfer pump; B3. Slurry transfer pump; B4. Prepolymer transfer pump; B5. Melt transfer pump; B6. Bottom transfer pump; w1. Process tower reflux EG pipe; w2. Condensate drain pipe; G1. PTA feed pipe; G2. EG feed pipe; G3. CHDM feed pipe; G4. NPG feed pipe; G5. Additive feed pipe; G6. Esterification reactor reflux EG pipe; G7. Heated EG pipe; G8 G9. Tower top tail gas heating pipe; G10. Tower top tail gas output pipe; G11. Heat medium heating pipe; G12. Sealed EG supply pipe; G13. Sealed EG recovery pipe; G14. Lubricating oil supply pipe; G15. Lubricating oil return pipe; G16. Cooling water supply pipe; G17. Cooling water return pipe; V1. EG supply regulating valve; V2. EG recovery regulating valve; Q1. EG supply flow meter; Q2. EG recovery flow meter; P1. EG supply pressure gauge; P2. EG outlet pressure gauge. Detailed Implementation

[0048] In the following description of the present invention, the terms "upper," "lower," "front," "rear," "left," "right," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not mean that the device must have a specific orientation. All pressures mentioned herein refer to absolute pressure.

[0049] To make the technical means, creative features, objectives and effects of this invention easier to understand, the invention will be further described below with reference to specific illustrations.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of the invention.

[0051] like Figure 1 As shown, the production system for multi-component copolymerized PETG of the present invention includes a CHDM premelting kettle 1, a CHDM intermediate tank 2, an NPG premelting kettle 3, an NPG intermediate tank 4, a slurry preparation tank 5, an esterification kettle 1 6, an esterification kettle 2 7, a prepolymerization kettle 8, a polycondensation kettle 2 9, and a final polycondensation kettle 10.

[0052] 1,4-Cyclohexanediethanol (CHDM) is melted separately in CHDM pre-melting reactor 1. The bottom outlet of CHDM pre-melting reactor 1 is connected to the top inlet of CHDM intermediate tank 2. The bottom outlet of CHDM intermediate tank 2 is connected to CHDM feed pipe G3 via CHDM transfer pump B1. CHDM feed pipe G3 is connected to the top inlet of slurry preparation tank 5 via CHDM flow meter and regulating valve. The temperature regulating valve of CHDM pre-melting reactor 1 is opened to heat it. After CHDM melts, it is mixed evenly by the action of a stirrer, and then discharged into CHDM intermediate tank 2 for temporary storage. Then, it is sent out by CHDM transfer pump B1, accurately metered by CHDM flow meter, and continuously added to slurry preparation tank 5 through CHDM feed pipe G3.

[0053] Neopentyl glycol (NPG) is melted separately in NPG pre-melting reactor 3. The bottom outlet of NPG pre-melting reactor 3 is connected to the top inlet of NPG intermediate tank 4. The bottom outlet of NPG intermediate tank 4 is connected to NPG feed pipe G4 via NPG transfer pump B2. NPG feed pipe G4 is connected to the top inlet of slurry preparation tank 5 via a flow meter and regulating valve. The temperature regulating valve of NPG pre-melting reactor 3 is opened to heat it. After the NPG melts, it is mixed evenly by the action of a stirrer, and then discharged into NPG intermediate tank 4 for temporary storage. Then, it is sent out by NPG transfer pump B2, accurately measured by the NPG flow meter, and continuously added to slurry preparation tank 5 through NPG feed pipe G4.

[0054] The slurry preparation tank 5 has a powder inlet at the top, which is connected to the PTA feed pipe G1, allowing PTA to be directly added into the slurry preparation tank 5. A spray column is also installed at the top of the slurry preparation tank 5. The top of the spray column is connected to the air inlet of a cyclone separator via an exhaust pipe. The top outlet of the cyclone separator is drawn in by an induced draft fan, and the powder settling at the bottom of the cyclone separator is returned to the top of the slurry preparation tank 5.

[0055] The inner cavity of the spray column is equipped with EG nozzles and additive nozzles from top to bottom. The EG nozzles are connected to the EG feed pipe G2, and the additive nozzles are connected to the additive feed pipe G5.

[0056] The outlet of the slurry preparation tank 5 is connected to the inlet of the esterification reactor 6 via the slurry transfer pump B3, and the bottom outlet of the esterification reactor 6 is connected to the inlet of the esterification reactor 7.

[0057] A solution of catalysts, stabilizers, colorants, and other additives in a certain proportion with PTA is sprayed downwards from the lower part of the spray column, while EG in a certain proportion with PTA is sprayed downwards from the upper part of the spray column. During the downward spraying process, EG is mixed with the catalyst, stabilizer, and colorant solution and then enters the slurry preparation tank 5 together.

[0058] The slurry preparation tank 5 is equipped with a stirrer and an insulation jacket. The quaternary raw materials PTA, EG, CHDM and NPG, along with catalysts, stabilizers, colorants, etc., are introduced into the slurry preparation tank 5 according to the production capacity and molar ratio. Through the action of the stirrer, PTA, EG, CHDM, NPG, catalysts, stabilizers, colorants, etc. are fully mixed and uniform. Then, the slurry is sent to the esterification reactor 6 through the slurry transfer pump B3 for esterification reaction.

[0059] The bottom of the esterification reactor 6 is connected to an auxiliary agent feed pipe G5, the inlet of which is connected to both the catalyst feed pipe and the stabilizer feed pipe. Adding a portion of the catalyst from the bottom of the esterification reactor reduces catalyst hydrolysis and consumption. The top exhaust port of the esterification reactor 6 is connected to the lower inlet of the process column 13, and the mixed vapor generated in the esterification reactor 6 is sent to the bottom of the process column 13 for distillation and separation.

[0060] The esterified material in esterification reactor 6 enters esterification reactor 7 under the influence of position and pressure differences. The top of esterification reactor 7 is connected to an auxiliary agent feed pipe G5, allowing for the addition of catalysts and other materials for further esterification. The top exhaust port of esterification reactor 7 is also connected to the lower inlet of process tower 13. The mixed vapor generated in esterification reactor 7 is also sent to the bottom of the shared process tower 13, where it is distilled and separated.

[0061] The bottom outlet of process tower 13 is connected to the inlet of bottom transfer pump B6. The outlet of bottom transfer pump B6 is divided into three paths. The first path is connected to the top reflux ports of esterification reactor 6 and esterification reactor 7 via esterification reactor reflux EG pipe G6. The second path is connected to ethylene glycol recycling tank 14. The third path is connected to the inlet of heat medium heating pipe G10 via heating EG pipe G7. The outlet of heat medium heating pipe G10 is connected to the inlet of heating coil of CHDM premelting reactor 1 and NPG premelting reactor 3. The outlet of heating coil of CHDM premelting reactor 1 and NPG premelting reactor 3 is connected to process tower reflux EG pipe w1.

[0062] The mixed vapors generated by esterification reactor 6 and esterification reactor 7 are sent to the bottom of process tower 13 for distillation and separation. The ethylene glycol at the bottom of process tower 13 is pumped out and divided into three streams. The first stream is metered by a flow meter and added to esterification reactor 6 and esterification reactor 7 respectively. The second stream is sent to ethylene glycol recycling tank 14. The third stream is sent to the jacket or coil of CHDM premelting reactor 1, NPG premelting reactor 3, CHDM intermediate tank 2, NPG intermediate tank 4 and slurry preparation tank 5 as a heat source.

[0063] The top outlet of process tower 13 is connected to the top tail gas outlet pipe G9 and the top tail gas heating pipe G8. The outlet of the top tail gas heating pipe G8 is also connected to the inlet of the heat medium heating pipe G10. The heating coil outlets of CHDM premelting kettle 1 and NPG premelting kettle 3 are also connected to the condensate drain pipe W2.

[0064] The outlet of the heat transfer medium heating pipe G10 is also connected to the heating jacket inlet of CHDM premelting kettle 1, CHDM intermediate tank 2, NPG premelting kettle 3, NPG intermediate tank 4 and slurry preparation tank 5 respectively. The heating jacket outlets of CHDM premelting kettle 1, CHDM intermediate tank 2, NPG premelting kettle 3, NPG intermediate tank 4 and slurry preparation tank 5 are respectively connected to the process tower reflux EG pipe w1 and condensate discharge pipe w2 through three-way valves.

[0065] The steam discharged from the top of process tower 13 serves as a heat source for the jackets or coils of the CHDM premelting vessel 1, NPG premelting vessel 3, CHDM intermediate tank 2, NPG intermediate tank 4, and slurry preparation tank 5, or as a heat source for the refrigeration unit, or as a power source for the steam turbine generator. The heat transfer medium in this patent can preferably be hot ethylene glycol or steam.

[0066] The outlet of the esterification reactor 7 is connected to the inlet of the prepolymerization reactor 8, the outlet of the prepolymerization reactor 8 is connected to the inlet of the polycondensation reactor 9, and the outlet of the polycondensation reactor 9 is connected to the inlet of the final polycondensation reactor 10.

[0067] The esterified material in esterification reactor 7 enters the prepolymerization reactor 8 from the bottom under the influence of position and pressure differences. An auxiliary agent feed pipe G5 is connected to the esterified material pipeline, allowing for the online addition of catalysts or other auxiliary agents as needed. Adding catalyst from the bottom of the prepolymerization reactor 8 also reduces catalyst hydrolysis and consumption. The esterified material undergoes a prepolymerization reaction in the prepolymerization reactor 8. The mixed vapor generated during the prepolymerization reaction is first cooled and collected by ethylene glycol spraying, and the remaining tail gas is removed by a vacuum system.

[0068] The prepolymer output from the prepolymerization reactor 8 is fed into the second polymerization reactor 9 under the action of position difference and pressure difference. The polymerization reaction is further carried out in the second polymerization reactor 9. The mixed vapor generated by the reaction is first cooled and captured by ethylene glycol spraying, and the remaining tail gas is also removed by the vacuum system.

[0069] The prepolymer material in the second polycondensation reactor 9 is conveyed by a gear pump, filtered by a prepolymer filter, and then sent to the final polycondensation reactor 10. Further polycondensation occurs in the final polycondensation reactor 10. The mixed vapors generated by the reaction are first cooled and captured by ethylene glycol spraying, and the remaining tail gas is removed by a vacuum system. The melt in the final polycondensation reactor 10 is conveyed by a melt transfer pump B5, filtered by a melt filter, and then sent to a pelletizer 11 for pelletizing and downstream user 12.

[0070] like Figure 2 , Figure 3 As shown, the polycondensation reactor 9 of the present invention includes a horizontal cylindrical body 9a, the two ends of which are closed by end caps 9b. A stirring shaft 9d is provided along the axis of the inner cavity of the cylinder. One end of the stirring shaft 9d passes through the center of the end cap and is supported in the end cap sealing seat 9c by a bearing. A sealing liquid sealing section and a lubricating oil sealing section are provided between the inner cavity of the end cap sealing seat 9c and the stirring shaft 9d. The sealing liquid sealing section is located in the part of the end cap sealing seat 9c near the end cap, and the lubricating oil sealing section is on the axial outer side of the sealing liquid sealing section.

[0071] Multiple sealing devices are installed between the inner cavity of the sealing fluid sealing section and the stirring shaft 9d. Typically, labyrinth seals and multiple pairs of skeleton oil seals are installed sequentially from the inside out to prevent leakage from the reactor. Each pair of skeleton oil seals is separated from the other by an oil separator ring. Each oil separator ring has radial through holes communicating with the sealing fluid channel. The inlet end of the sealing fluid channel communicates with the sealing fluid inlet c1 on the outer wall of the end cap sealing seat 9c, and the outlet end communicates with the sealing fluid outlet c2 on the outer wall of the end cap sealing seat 9c. The inlet of the sealing fluid sealing section is connected to the sealing EG supply pipe G11, and the outlet of the sealing fluid sealing section is connected to the EG recycling system through the sealing EG recovery pipe G12.

[0072] This polymerization reactor does not use traditional methyl silicone oil as a sealing fluid; instead, it uses ethylene glycol (EG), the raw material for this production line, as the sealing fluid. Ethylene glycol flows out from the sealing EG supply pipe G11 and enters the inner cavity of the sealing section through the sealing fluid inlet c1. It flows through each of the oil seals in the sealing section, causing the lips of each oil seal to open and tightly grip the stirring shaft 9d, preventing ethylene glycol leakage and carrying away the heat conducted from the stirring shaft 9d, thus extending the service life of each oil seal. Ethylene glycol flowing out from the sealing fluid outlet c2 enters the EG recycling system through the sealing EG recovery pipe G12 for recovery, and is then sent to the slurry preparation system to continue participating in production. This achieves both material recovery and heat recovery from the ethylene glycol, reducing the energy consumption of the polymerization system.

[0073] The sealed EG supply pipe G11 is connected to the sealing liquid inlet c1 via the EG supply regulating valve V1 and the EG supply flow meter Q1. The opening of the EG supply regulating valve V1 is adjusted according to the EG inlet flow detected by the EG supply flow meter Q1. An EG supply pressure gauge P1 can also be installed at the sealing liquid inlet c1 to display the pressure of the sealed EG supply pipe G11 and monitor for ethylene glycol leakage.

[0074] An EG recovery regulating valve V2 and an EG recovery flow meter Q2 are installed on the sealed EG recovery pipe G12. By comparing the flow rate of the EG recovery flow meter Q2 with that of the EG supply flow meter Q1, it is easy to determine whether there is a leak in the sealing section of the sealing fluid.

[0075] The outlet of the sealing fluid sealing section is also equipped with an EG outlet pressure gauge P2. By comparing the pressure difference displayed by the EG outlet pressure gauge P2 and the EG supply pressure gauge P1, the resistance of the sealing fluid sealing section can be determined, and it can also be determined whether there is a leak.

[0076] Even if a certain amount of ethylene glycol leakage from the sealing section of the sealing fluid into the reactor is found during the production process, since ethylene glycol is one of the main raw materials in the slurry preparation, a small amount of ethylene glycol leaking into the reactor will not cause material contamination like methyl silicone oil sealing fluid. Production can continue, and maintenance can be carried out at an appropriate time to avoid production line shutdown losses.

[0077] A bearing is installed between the inner cavity of the lubricating oil sealing section and the stirring shaft 9d, and a skeleton oil seal is installed on both sides of the bearing. The lower part of the outer wall of the end cover sealing seat 9c is provided with a lubricating oil inlet c3, and the upper part is provided with a lubricating oil outlet c4, both of which communicate with the space where the bearing is located.

[0078] A secondary oil tank 9g is fixed to the housing of the reducer 9e. It stores the lubricating oil in the sealing section separately and also acts as a buffer. The inner cavity of the secondary oil tank 9g is equipped with a cooling coil. The two ends of the cooling coil extend out of the housing of the secondary oil tank 9g. The inlet of the cooling coil is connected to the cooling water supply pipe G15, and the outlet of the cooling coil is connected to the cooling water return pipe G16. This is used to control the temperature of the lubricating oil.

[0079] The outer end of the stirring shaft 9d is connected to the output shaft of the reducer 9e. A shaft-end pump 9f is installed on the input shaft of the reducer 9e. The input shaft of the reducer 9e is driven by a main motor. The input shaft transmits power to the output shaft via a gear reduction mechanism, achieving speed reduction. The output shaft drives the stirring shaft 9d to rotate, agitating the melt and accelerating its devolatilization. The reducer 9e is fixed to the base via a torque arm 9h to secure the reducer housing and withstand the reaction force generated by the drive.

[0080] The inlet of the shaft-end pump 9f is connected to the outlet of the auxiliary oil tank 9g, and the outlet of the shaft-end pump 9f is connected to the inlet of the lubricating oil sealing section. The outlet of the lubricating oil sealing section is connected to the return port of the auxiliary oil tank 9g through the lubricating oil return pipe G14. On the other hand, the input shaft drives the shaft-end pump 9f to operate. The shaft-end pump 9f draws lubricating oil from the auxiliary oil tank 9g and sends it through the lubricating oil supply pipe G13 to the lubricating oil inlet c3 of the lubricating oil sealing section. After entering the bearing space, the bearing is lubricated and cooled. Then, the lubricating oil flows out from the lubricating oil outlet c4 and returns to the auxiliary oil tank 9g through the lubricating oil return pipe G14 for circulation.

[0081] During normal operation, the temperature inside the polycondensation reactor is very high, which will cause the temperature of the lubricating oil to rise. Cooling water is sent to the cooling coil through the cooling water supply pipe G15 to indirectly cool the lubricating oil. The heated cooling water flows out from the cooling water return pipe G16.

[0082] like Figures 4 to 7 As shown, the final polycondensation reactor 10 of this invention includes a horizontal cylindrical body 10a. A heating jacket 10a3 is provided on the outer periphery of the cylindrical body 10a to heat the melt inside the inner cavity of the cylindrical body. A rotor shaft 10b is axially mounted inside the inner cavity of the cylindrical body 10a. Both ends of the rotor shaft 10b extend from the end cover of the cylindrical body and are supported on the frame by bearing seats. Multiple seals are provided where the rotor shaft passes through the end cover of the cylindrical body. A gas phase outlet 10a1 is provided at the top of the cylindrical body 10a, and a melt outlet 10a2 is provided at the bottom of the discharge end of the cylindrical body 10a.

[0083] Multiple parallel annular disks 10c are fixed along the axial direction of the rotor shaft 10b. Each annular disk 10c is fixed to the free end of multiple spokes 10f, and the number of spokes 10f can be five or six depending on the situation. The spokes 10f are evenly distributed radially and their roots are fixed to the rotor shaft 10b. A rotating scraper 10g is welded to the free end of each spoke 10f. The rotating scraper 10g extends beyond the outer edge of the annular disks 10c and extends along the axial direction of the cylinder. The blade of each rotating scraper 10g points towards the inner wall of the cylinder, and the distance GAP1 between the scraper and the bottom wall of the cylinder is 40±2mm.

[0084] Since the melt is only located in the bottom area of ​​the cylinder 10a, and the upper part of the inner cavity of the cylinder is a devolatilization space with no assembly requirements with the rotor, the rotor shaft 10b is eccentrically set in the inner cavity of the cylinder, with the rotor shaft axis located directly below the cylinder axis, so as to accurately control the gap between the rotating scraper 10g and the bottom wall of the cylinder.

[0085] The rotor shaft 10b drives each annular disk 10c to rotate via spokes 10f. The bottom of the annular disk 10c is immersed in the melt at the bottom of the cylinder, and then rotates to the upper devolatilization space. The melt forms a film on both sides of the annular disk 10c, increasing the specific surface area of ​​the melt, which is conducive to the overflow of small molecules and their extraction from the gas phase outlet 10a1. The melt undergoes condensation polymerization, increasing its molecular weight. Since the temperature of the inner wall of the cylinder is the highest, the melt adhering to the inner wall for a long time can easily cause overheating or even carbonization, producing black spots and affecting product quality. When the annular disk 10c rotates, the rotating scraper 10g continuously refreshes the material on the bottom wall of the cylinder to prevent overheating.

[0086] Baffles 10d are provided between adjacent annular disks 10c. The bottom of each baffle 10d is fixed to the inner wall of the cylinder, and a disc scraper 10h is fixed to the upper edge of each baffle 10d. The two blades of the disc scraper 10h point to the side walls of the adjacent annular disks 10c, and the gaps GAP3 and GAP4 between the disc scraper 10h and the two annular disks 10c are controlled at 30±2mm. When the annular disks 10c rotate with the rotor shaft 10b, the film on both sides of the annular disks 10c undergoes devolatilization in the gas phase space. Just as it is about to re-enter below the melt surface, the disc scraper 10h scrapes off the film exceeding 30±2mm. After scraping, the annular disks 10c are transferred into the melt to re-attach film, thereby achieving forced renewal of the melt film on the annular disks 10c.

[0087] Each baffle 10d has a rotating scraper 10e at its upper center. Each rotating scraper 10e extends axially along the cylinder body, with its blade pointing towards the outer periphery of the rotor shaft 10b. The distance GAP2 between the scraper 10e and the outer periphery of the rotor shaft 10b is 30±2mm. The molten film from the annular disk 10c continuously falls onto the rotor shaft 10b, causing a film to form on the outer periphery of the rotor shaft 10b. As the rotor shaft 10b rotates, the blade of the rotating scraper 10e continuously removes the molten film from it, achieving continuous renewal.

[0088] Since the baffle 10d is relatively thin and has low strength, the upper edge of each baffle 10d is provided with a thickened baffle beam 10d1, and the roots of each disc scraper 10h and rotating shaft scraper 10e can be welded to the corresponding baffle beam 10d1.

[0089] For high-viscosity melts, as each annular disk 10c cuts into the melt and continues to rotate, it carries the melt backward and upward, causing the melt surface to exhibit a noticeable tilt. Therefore, tilting the upper edge of each baffle 10d along the melt surface better matches the actual operating conditions of the equipment. The disc scraper 10h is positioned at the lower edge of the baffle 10d, scraping off the old film before the annular disk 10c enters the melt, allowing the new melt to form a film.

[0090] Each baffle 10d has multiple baffle flow channels 10d2 at its bottom to facilitate the flow of the melt towards the discharge end, and finally out from the melt outlet 10a2. Between adjacent baffle flow channels 10d2 are baffle fixing points 10d3, and each baffle fixing point 10d3 is supported on the inner wall of the cylinder.

[0091] A baffle 10d is also provided between the melt outlet 10a2 and the adjacent annular disk 10c to maintain a certain liquid level of the melt at the bottom of the cylinder.

[0092] Each rotating scraper 10g has a pushing angle with the rotor shaft axis that pushes the material toward the discharge end of the reactor. While updating the material on the bottom wall of the cylinder, each rotating scraper 10g also pushes the melt, making it easier for the melt to flow toward the melt outlet 10a2.

[0093] The method for producing multi-component copolymer PETG of the present invention comprises the following steps in sequence:

[0094] S1. Slurry preparation: Terephthalic acid, ethylene glycol, 1,4-cyclohexanediethanol, neopentyl glycol, catalyst, stabilizer, and colorant are added to slurry preparation tank 5 in a certain proportion and mixed thoroughly. 1,4-cyclohexanediethanol and neopentyl glycol are melted separately in separate pre-melting kettles. After melting, they are discharged to their respective finished product tanks and continuously added to slurry preparation tank 5 after being metered by a flow meter.

[0095] S2, Esterification reaction: The slurry in the slurry preparation tank is transported to the esterification reactor 6 through the slurry transfer pump B3 for esterification reaction. The esterified material in the esterification reactor 6 enters the esterification reactor 7 under the action of position difference and pressure difference for further esterification reaction.

[0096] S3, Prepolymerization reaction: The esterified material in the esterification reactor 7 enters the prepolymerization reactor 8 under the action of position difference and pressure difference to carry out the prepolymerization reaction and obtain the prepolymer.

[0097] S4. Polycondensation reaction: The prepolymer in the prepolymerization reactor 8 enters the second polycondensation reactor 9 under the action of position difference and pressure difference, and further undergoes the polycondensation reaction;

[0098] S5. Final polycondensation reaction: The prepolymer in the polycondensation reactor 9 is sent to the final polycondensation reactor 10 by the prepolymer transfer pump B4 for further polycondensation reaction to obtain PETG melt.

[0099] The molar ratio of the quaternary monomers is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediol: neopentyl glycol = 1:0.9:0.2:0.15, and the total alcohol-acid ratio is 1.25:1;

[0100] The stabilizer is triphenyl phosphite, added at a rate of 30 ppm relative to terephthalic acid;

[0101] The colorant is a red and blue pigment, added at a rate of 0.5 ppm relative to terephthalic acid;

[0102] The catalyst is a composite catalyst composed of tetrabutyl titanate, antimony acetate and ethyl silicate, wherein the amount of tetrabutyl titanate relative to terephthalic acid is 40 ppm, the amount of antimony acetate relative to terephthalic acid is 9 ppm, and the amount of ethyl silicate relative to terephthalic acid is 4.5 ppm.

[0103] The reaction pressure in esterification reactor 6 was 100 kPa, the reaction temperature was 185 °C, and the residence time was 2.0 h.

[0104] The reaction pressure in reactor 7 of the esterification reactor was 5 kPa, the reaction temperature was 241 °C, and the residence time was 1.0 h.

[0105] The reaction pressure in the prepolymerization reactor 8 is 5 kPa, the reaction temperature is 246 °C, and the residence time is 0.5 h.

[0106] The reaction pressure in the second polycondensation reactor 9 was 0.5 kPa, the reaction temperature was 259 °C, and the residence time was 1 h.

[0107] The reaction pressure in the final polycondensation reactor 10 is 50 Pa, the reaction temperature is 269 °C, and the residence time is 2 h.

[0108] The intrinsic viscosity IV of the melt at the outlet of the final polycondensation reactor 10 is 0.681 dl / g (decyl / gram), the color value L is 84, and the color value b is 3.2. The mechanical properties of the melt after pelleting and injection molding are as follows: elongation at break is 123%, yield strength is 49 MPa, and tensile modulus of elasticity is 953 MPa.

[0109] The molar ratio of the quaternary monomers is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediol: neopentyl glycol = 1:0.8:0.2:0.3, and the total alcohol-acid ratio is 1.3:1;

[0110] The stabilizer is triphenyl phosphite, added at a rate of 30 ppm relative to terephthalic acid;

[0111] The colorant is a red and blue pigment, added at a rate of 0.5 ppm relative to terephthalic acid;

[0112] The catalyst is a composite catalyst composed of tetrabutyl titanate, antimony acetate and ethyl silicate, wherein the amount of tetrabutyl titanate relative to terephthalic acid is 40 ppm, the amount of antimony acetate relative to terephthalic acid is 9 ppm, and the amount of ethyl silicate relative to terephthalic acid is 4.5 ppm.

[0113] The reaction pressure in esterification reactor 6 was 200 kPa, the reaction temperature was 200 °C, and the residence time was 2.5 h.

[0114] The reaction pressure in reactor 7 of the esterification reactor was 20 kPa, the reaction temperature was 243 °C, and the residence time was 1.5 h.

[0115] The reaction pressure in the prepolymerization reactor 8 is 10 kPa, the reaction temperature is 250°C, and the residence time is 0.75 h.

[0116] The reaction pressure in the second polycondensation reactor (reactor 9) was 0.8 kPa, the reaction temperature was 260 °C, and the residence time was 1.5 h.

[0117] The reaction pressure in the final polycondensation reactor 10 is 200 Pa, the reaction temperature is 270 °C, and the residence time is 2.5 h.

[0118] The intrinsic viscosity IV of the melt at the outlet of the final polycondensation reactor 10 is 0.685 dl / g, the color value L is 85, and the color value b is 3.5. The mechanical properties of the melt after pelleting and injection molding are as follows: elongation at break is 189%, yield strength is 48 MPa, and tensile modulus of elasticity is 964 MPa.

[0119] The molar ratio of the quaternary monomers is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediol: neopentyl glycol = 1:0.7:0.3:0.3, and the total alcohol-acid ratio is 1.3:1;

[0120] The stabilizer is triethyl phosphite, added at a rate of 28 ppm relative to terephthalic acid;

[0121] The colorant is a red and blue pigment, and the amount added relative to terephthalic acid is 1 ppm;

[0122] The catalyst is a composite catalyst composed of tetrabutyl titanate, antimony acetate and ethyl silicate, wherein the amount of tetrabutyl titanate relative to terephthalic acid is 65 ppm, the amount of antimony acetate relative to terephthalic acid is 15 ppm, and the amount of ethyl silicate relative to terephthalic acid is 7 ppm.

[0123] The reaction pressure in esterification reactor 6 was 150 kPa, the reaction temperature was 195 °C, and the residence time was 3 h.

[0124] The reaction pressure in reactor 7 of the esterification reactor was 30 kPa, the reaction temperature was 242 °C, and the residence time was 1.5 h.

[0125] The reaction pressure in the prepolymerization reactor 8 is 15 kPa, the reaction temperature is 248 °C, and the residence time is 0.5 h.

[0126] The reaction pressure in the second polycondensation reactor 9 was 1 kPa, the reaction temperature was 265 °C, and the residence time was 1.5 h.

[0127] The reaction pressure in the final polycondensation reactor 10 is 150 Pa, the reaction temperature is 275 °C, and the residence time is 2 h.

[0128] The intrinsic viscosity IV of the melt at the outlet of the final polycondensation reactor 10 is 0.786 dl / g, the color value L is 82, and the color value b is 2.6. The mechanical properties of the melt after pelleting and injection molding are as follows: elongation at break is 202%, yield strength is 50 MPa, and tensile modulus of elasticity is 950 MPa.

[0129] The molar ratio of the quaternary monomers is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediol: neopentyl glycol = 1:0.7:0.4:0.2, and the total alcohol-acid ratio is 1.3:1;

[0130] The stabilizer is triphenyl phosphite, added at a rate of 53 ppm relative to terephthalic acid;

[0131] The colorant is a red and blue pigment, and the amount added relative to terephthalic acid is 1 ppm;

[0132] The catalyst is a composite catalyst composed of tetrabutyl titanate, antimony acetate and ethyl silicate, wherein the amount of tetrabutyl titanate relative to terephthalic acid is 70 ppm, the amount of antimony acetate relative to terephthalic acid is 16 ppm, and the amount of ethyl silicate relative to terephthalic acid is 8 ppm.

[0133] The reaction pressure in esterification reactor 6 was 250 kPa, the reaction temperature was 220 °C, and the residence time was 3 h.

[0134] The reaction pressure in reactor 7 of the esterification reactor was 40 kPa, the reaction temperature was 245 °C, and the residence time was 1.75 h.

[0135] The reaction pressure in the prepolymerization reactor 8 is 10 kPa, the reaction temperature is 252 °C, and the residence time is 0.75 h.

[0136] The reaction pressure in the second polycondensation reactor 9 was 1.5 kPa, the reaction temperature was 260 °C, and the residence time was 1.75 h.

[0137] The reaction pressure in the final polycondensation reactor 10 is 300 Pa, the reaction temperature is 270 °C, and the residence time is 2.5 h.

[0138] The intrinsic viscosity IV of the melt at the outlet of the final polycondensation reactor 10 is 0.82 dl / g, the color value L is 87, and the color value b is 2.1. The mechanical properties of the melt after pelleting and injection molding are as follows: elongation at break is 228%, yield strength is 48 MPa, and tensile modulus of elasticity is 920 MPa.

[0139] The molar ratio of the quaternary monomers is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediol: neopentyl glycol = 1:0.5:0.5:0.6, and the total alcohol-acid ratio is 1.6:1;

[0140] The stabilizer is triphenyl phosphite, with an addition amount of 68 ppm relative to terephthalic acid;

[0141] The colorant is a red and blue pigment, and the amount added relative to terephthalic acid is 2 ppm;

[0142] The catalyst is a composite catalyst composed of tetrabutyl titanate, antimony acetate and ethyl silicate, wherein the amount of tetrabutyl titanate relative to terephthalic acid is 90 ppm, the amount of antimony acetate relative to terephthalic acid is 20 ppm, and the amount of ethyl silicate relative to terephthalic acid is 10 ppm.

[0143] The reaction pressure in esterification reactor 6 was 240 kPa, the reaction temperature was 230 °C, and the residence time was 3.5 h.

[0144] The reaction pressure in reactor 7 of the esterification reactor was 45 kPa, the reaction temperature was 245 °C, and the residence time was 1.5 h.

[0145] The reaction pressure in the prepolymerization reactor 8 is 15 kPa, the reaction temperature is 255 °C, and the residence time is 1 h.

[0146] The reaction pressure in the second polycondensation reactor 9 was 1 kPa, the reaction temperature was 263 °C, and the residence time was 2 h.

[0147] The reaction pressure in the final polycondensation reactor 10 is 350 Pa, the reaction temperature is 272 °C, and the residence time is 2.5 h.

[0148] The intrinsic viscosity IV of the melt at the outlet of the final polycondensation reactor 10 is 0.83 dl / g, the color value L is 86, and the color value b is 1.8.

[0149] The mechanical properties of the melt pellet injection molding are as follows: elongation at break is 192%, yield strength is 47 MPa, and tensile modulus of elasticity is 853 MPa.

[0150] The molar ratio of the quaternary monomers is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediol: neopentyl glycol = 1:0.5:0.5:0.7, and the total alcohol-acid ratio is 1.7:1;

[0151] The stabilizer is triethyl phosphite, added at a rate of 41 ppm relative to terephthalic acid;

[0152] The colorant is a red and blue pigment, and the amount added relative to terephthalic acid is 2 ppm;

[0153] The catalyst is a composite catalyst composed of tetrabutyl titanate, antimony acetate and ethyl silicate, wherein the amount of tetrabutyl titanate relative to terephthalic acid is 100 ppm, the amount of antimony acetate relative to terephthalic acid is 23 ppm, and the amount of ethyl silicate relative to terephthalic acid is 11 ppm.

[0154] The reaction pressure in esterification reactor 6 was 300 kPa, the reaction temperature was 240 °C, and the residence time was 4 h.

[0155] The reaction pressure in esterification reactor 7 was 50 kPa, the reaction temperature was 245 °C, and the residence time was 2 h.

[0156] The reaction pressure in the prepolymerization reactor 8 is 20 kPa, the reaction temperature is 258 °C, and the residence time is 1 h.

[0157] The reaction pressure in the second polycondensation reactor 9 was 2 kPa, the reaction temperature was 268°C, and the residence time was 2 h.

[0158] The reaction pressure in the final polycondensation reactor 10 is 400 Pa, the reaction temperature is 278 °C, and the residence time is 3 h.

[0159] The intrinsic viscosity (IV) of the melt at the outlet of the final polycondensation reactor 10 is 0.86 dl / g, the color value (L) is 83, and the color value (b) is 2.3.

[0160] The mechanical properties of the melt pellet injection molding are as follows: elongation at break is 190%, yield strength is 49 MPa, and tensile modulus of elasticity is 868 MPa.

[0161] The molar ratio of the raw materials is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediethanol: neopentyl glycol = 1:1:0:0.8, the total alcohol-acid ratio is 1.8:1, and no stabilizers or colorants are added;

[0162] The catalyst used was antimony acetate, added at a rate of 429 ppm relative to terephthalic acid, with the rest being the same as in Example 1.

[0163] The intrinsic viscosity IV of the melt at the outlet of the final polycondensation reactor 10 is 0.68 dl / g, the color value L is 75, and the color value b is 6.

[0164] The mechanical properties of the melt pellet injection molding are as follows: elongation at break is 102%, yield strength is 46 MPa, and tensile modulus of elasticity is 813 MPa.

[0165] The molar ratio of the raw materials is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediethanol: neopentyl glycol = 1:1.2:0.6:0, the total alcohol-acid ratio is 1.8:1, and no stabilizers or colorants are added;

[0166] The catalyst used was tetrabutyl titanate, added at a rate of 150 ppm relative to terephthalic acid, and otherwise the same as in Example 2.

[0167] The intrinsic viscosity IV of the melt at the outlet of the final polycondensation reactor 10 is 0.862 dl / g, the color value L is 70, and the color value b is 8.

[0168] The mechanical properties of the melt pellet injection molding are as follows: elongation at break is 173%, yield strength is 44 MPa, and tensile modulus of elasticity is 734 MPa.

[0169] The molar ratio of the raw materials is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediethanol: neopentyl glycol = 1:0.4:0.7:0.8, the total alcohol-acid ratio is 1.9:1, and no stabilizers or colorants are added;

[0170] The catalyst used was antimony acetate, added at a rate of 547 ppm relative to terephthalic acid, with the rest being the same as in Example 3.

[0171] The intrinsic viscosity IV of the melt at the outlet of the final polycondensation reactor 10 is 0.8 dl / g, the color value L is 73, and the color value b is 7.

[0172] The mechanical properties of the melt pellet injection molding are as follows: elongation at break is 183%, yield strength is 55 MPa, and tensile modulus of elasticity is 803 MPa.

[0173] The performance parameters of Examples 1 to 6 and Comparative Examples 1 to 3 are summarized below:

[0174]

[0175] As can be seen from Examples 1 to 6 and Comparative Examples 1 to 3, the elongation at break of the product gradually increases with the increase of CHDM and NPG content. After the molar ratio of CHDM+NPG to PTA reaches 0.6, the elongation at break of the product decreases with the increase of CHDM and NPG content. The elongation at break and tensile modulus of elasticity of the Examples are significantly better than those of the Comparative Examples.

[0176] Examples 1 to 6, which use a composite catalyst composed of tetrabutyl titanate, antimony acetate, and ethyl silicate, have significantly lower usage amounts than Comparative Examples 1 and 3, which use antimony acetate alone, and lower usage amounts than Comparative Example 2, which uses tetrabutyl titanate alone. The products using the composite catalyst have excellent color values, characterized by high L values ​​and low b values.

[0177] The products in Examples 1, 2, 4, and 5, which used triphenyl phosphite as a stabilizer, had better color than those in Examples 3 and 6, which used triethyl phosphite, showing a slightly higher L value and a slightly lower b value.

[0178] The above description is merely a preferred embodiment of the present invention, showing and describing the basic principles, main features, and advantages of the present invention. It is not intended to limit the scope of patent protection of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. In addition to the above embodiments, the present invention may have other implementations without departing from the spirit and scope of the invention. Various changes and modifications to the present invention are possible, and all technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by the present invention. The scope of protection of the present invention is defined by the appended claims and their equivalents. Technical features not described in the present invention can be implemented by or using existing technology, and will not be elaborated here.

Claims

1. A production system for multi-component copolymerized PETG, comprising a slurry preparation tank, wherein the top of the slurry preparation tank is connected to a PTA feed pipe, an EG feed pipe, and an auxiliary agent feed pipe, and the outlet of the slurry preparation tank is connected to the inlet of an esterification reactor via a slurry transfer pump, characterized in that: It also includes a CHDM premelting kettle and an NPG premelting kettle. The bottom outlet of the CHDM premelting kettle is connected to the top inlet of the CHDM intermediate tank, and the bottom outlet of the CHDM intermediate tank is connected to the CHDM feed pipe via a CHDM transfer pump. The bottom outlet of the NPG premelting kettle is connected to the top inlet of the NPG intermediate tank, and the bottom outlet of the NPG intermediate tank is connected to the NPG feed pipe via an NPG transfer pump. The CHDM feed pipe and the NPG feed pipe are respectively connected to the top inlet of the slurry preparation tank via flow meters and regulating valves. The bottom outlet of the first esterification kettle is connected to the inlet of the second esterification kettle. The outlet of the esterification reactor is connected to the inlet of the prepolymerization reactor, the outlet of the prepolymerization reactor is connected to the inlet of the polycondensation reactor, and the outlet of the polycondensation reactor is connected to the inlet of the final polycondensation reactor. The final polycondensation reactor includes a horizontal cylindrical body. A rotor shaft is installed axially in the inner cavity of the cylindrical body. Multiple parallel annular disks are fixed along the axial direction of the rotor shaft. Each annular disk is fixed to the rotor shaft by spokes that are radially and evenly distributed. A rotating scraper is fixed to the free end of each spoke. The rotating scraper extends beyond the outer edge of the annular disk and the blade points towards the inner wall of the cylindrical body. A baffle fixed to the inner wall of the cylinder is provided between adjacent annular discs. A disc scraper is fixed to the upper edge of each baffle. The two blades of the disc scraper point to the side walls of the adjacent annular discs on both sides, and the disc scraper is located at the lower end of the baffle that is inclined along the bottom of the cylinder to the molten liquid surface. Each of the baffles has multiple baffle flow channels at its bottom for the melt to pass through, and the baffle fixing points between adjacent baffle flow channels are connected to the inner wall of the cylinder. Each baffle has a rotating scraper fixed at its upper center. Each rotating scraper extends along the cylinder axis with its blade pointing towards the outer periphery of the rotor shaft. Each baffle has a thickened baffle beam at its upper edge. The roots of each disc scraper and rotating scraper are welded to the corresponding baffle beam.

2. The production system for multi-component copolymerized PETG according to claim 1, characterized in that: The top exhaust ports of the first and second esterification reactors are connected to the lower inlet of the process tower, the bottom outlet of the process tower is connected to the inlet of the bottom transfer pump, the outlet of the bottom transfer pump is connected to the EG reflux pipe of the esterification reactor and the ethylene glycol recycling tank, and the outlet of the EG reflux pipe of the esterification reactor is connected to the top reflux port of the first and second esterification reactors.

3. The production system for multi-component copolymerized PETG according to claim 2, characterized in that: The outlet of the bottom pump is also connected to the inlet of the heat medium heating pipe via a heated EG pipe. The outlet of the heat medium heating pipe is connected to the inlet of the heating coil of the CHDM premelting kettle and the NPG premelting kettle, respectively. The outlet of the heating coil of the CHDM premelting kettle and the NPG premelting kettle is connected to the reflux EG pipe of the process tower.

4. The production system for multi-component copolymerized PETG according to claim 3, characterized in that: The top outlet of the process tower is connected to the top tail gas output pipe and the top tail gas heating pipe, and the outlet of the top tail gas heating pipe is also connected to the inlet of the heat medium heating pipe; the outlet of the heating coil of the CHDM premelting kettle and the NPG premelting kettle is also connected to the condensate discharge pipe.

5. The production system for multi-component copolymerized PETG according to claim 3, characterized in that: The outlet of the heat transfer medium heating pipe is connected to the heating jacket inlet of the CHDM premelting kettle, CHDM intermediate tank, NPG premelting kettle, NPG intermediate tank and slurry preparation tank respectively. The heating jacket outlet of the CHDM premelting kettle, CHDM intermediate tank, NPG premelting kettle, NPG intermediate tank and slurry preparation tank is connected to the process tower reflux EG pipe and condensate discharge pipe respectively through a three-way valve.

6. The production system for multi-component copolymerized PETG according to claim 1, characterized in that: The bottom of the esterification reactor, the top of the esterification reactor, and the bottom of the prepolymerization reactor are respectively connected to the auxiliary agent feed pipes, and the inlets of the auxiliary agent feed pipes are respectively connected to the catalyst feed pipe and the stabilizer feed pipe.

7. The production system for multi-component copolymerized PETG according to claim 1, characterized in that: The polycondensation reactor includes a horizontal cylindrical body. A stirring shaft is arranged along the axis of the inner cavity of the cylinder. One end of the stirring shaft extends from the center of the end cover and is supported by a bearing in the end cover sealing seat. A sealing fluid sealing section and a lubricating oil sealing section are arranged from the inside out between the inner cavity of the end cover sealing seat and the stirring shaft. The outer end of the stirring shaft is connected to the output shaft of a reducer. The reducer is characterized by: a secondary oil tank fixed to its housing; a cooling coil installed in the inner cavity of the secondary oil tank; a shaft-end pump installed at the input shaft end of the reducer; the inlet of the shaft-end pump connected to the outlet of the secondary oil tank; the outlet of the shaft-end pump connected to the inlet of the lubricating oil sealing section; and the outlet of the lubricating oil sealing section connected to the return port of the secondary oil tank. The inlet of the sealing fluid sealing section is connected to a sealing EG supply pipe, and the outlet of the sealing fluid sealing section is connected to an EG recycling system via a sealing EG recovery pipe.

8. A method for producing multi-component copolymerized PETG, characterized in that, The steps are as follows: S1. Slurry preparation: Terephthalic acid, ethylene glycol, 1,4-cyclohexanediol, neopentyl glycol, catalyst, stabilizer and colorant are added to the slurry preparation tank in a certain proportion and mixed thoroughly. S2, Esterification reaction: The slurry in the slurry preparation tank is transported to the first esterification reactor by the slurry transfer pump for esterification reaction. The esterified material in the first esterification reactor enters the second esterification reactor under the action of position difference and pressure difference for further esterification reaction. S3. Prepolymerization reaction: The esterified material in the esterification reactor enters the prepolymerization reactor under the action of position difference and pressure difference to carry out the prepolymerization reaction and obtain the prepolymer. S4. Polycondensation reaction: The prepolymer in the prepolymerization reactor enters the second polycondensation reactor under the action of position difference and pressure difference, and further undergoes the polycondensation reaction. S5. Final polycondensation reaction: The prepolymer in the second polycondensation reactor is sent to the final polycondensation reactor by the prepolymer transfer pump for further polycondensation reaction to obtain PETG melt. The molar ratio of the quaternary monomers is as follows: terephthalic acid: ethylene glycol: 1,4-cyclohexanediethanol: neopentyl glycol = 1: (0.5-0.9): (0.2-0.5): (0.15-0.7). The catalyst is a composite catalyst composed of tetrabutyl titanate, antimony acetate and ethyl silicate, wherein the amount of tetrabutyl titanate relative to terephthalic acid is 40-100 ppm, the amount of antimony acetate relative to terephthalic acid is 9-23 ppm, and the amount of ethyl silicate relative to terephthalic acid is 4.5-11 ppm.

9. The method for producing multi-component copolymerized PETG according to claim 8, characterized in that, The stabilizer is triphenyl phosphite or triethyl phosphite, wherein the amount of triphenyl phosphite relative to terephthalic acid is 30-68 ppm, and the amount of triethyl phosphite relative to terephthalic acid is 28-41 ppm. The colorant is a red or blue pigment, and the amount added relative to terephthalic acid is 0.5 to 2 ppm.

10. The method for producing multi-component copolymerized PETG according to claim 8, characterized in that, The molar ratio of the quaternary monomers is as follows: phthalic acid: ethylene glycol: 1,4-cyclohexanediethanol: neopentyl glycol = 1:0.7:0.4:0.2; the intrinsic viscosity (IV) of the product is ≥0.8 dl / g, the color value (L) is ≥87, the color value (b) is ≤2.1, the elongation at break is ≥220%, the yield strength is ≥48 MPa, and the tensile modulus of elasticity is ≥920 MPa.

11. The method for producing multi-component copolymerized PETG according to claim 8, characterized in that, The 1,4-cyclohexanediethanol and neopentyl glycol are melted in separate pre-melting kettles, and after melting, they are discharged to their respective finished product tanks. After being metered by a flow meter, they are continuously added to the slurry preparation tank.

12. The method for producing multi-component copolymerized PETG according to claim 8, characterized in that, The reaction pressure in the esterification reactor is 100–300 kPa, the reaction temperature is 185–240 °C, and the residence time is 2.0–4 h. The reaction pressure in the esterification reactor is 5–50 kPa, the reaction temperature is 241–245 °C, and the residence time is 1.0–2 h. The reaction pressure in the prepolymerization reactor is 5–20 kPa, the reaction temperature is 246–258 °C, and the residence time is 0.5–1 h. The reaction pressure in the polycondensation reactor is 0.5–2 kPa, the reaction temperature is 259–268 °C, and the residence time is 1–2 h. The reaction pressure in the final polycondensation reactor is 50–400 Pa, the reaction temperature is 269–278 °C, and the residence time is 2–3 h.

13. The method for producing multi-component copolymerized PETG according to claim 8, characterized in that, Catalysts are added from the bottom of the esterification reactor and the prepolymerization reactor, respectively. The mixed vapors generated by the esterification reactor and the prepolymerization reactor are sent to the bottom of the process tower for distillation and separation. The ethylene glycol at the bottom of the process tower is pumped out and divided into three streams. The first stream is metered by a flow meter and added to the esterification reactor and the prepolymerization reactor, respectively. The second stream is sent to the ethylene glycol recycling tank. The third stream is sent to the jacket or coil of the CHDM premelting reactor, the NPG premelting reactor, the CHDM intermediate tank, the NPG intermediate tank and the slurry preparation tank as a heat source.

14. The method for producing multi-component copolymerized PETG according to claim 13, characterized in that, The steam discharged from the top of the process tower serves as a heat source for the jackets or coils of the CHDM premelting kettle, NPG premelting kettle, CHDM intermediate tank, NPG intermediate tank and slurry preparation tank, or as a heat source for the refrigeration unit, or as a power source for the steam turbine generator.

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