Polymerization vessel for high viscosity PETG or PCTG and polymerization method for PETG or pctg

Abstract

The present invention relates to a polymerization vessel for high viscosity PETG or PCTG and a polymerization method for PETG or PCTG. The polymerization vessel is provided with front and rear dual parallel shafts, and a plurality of circular tray reactors are arranged on the dual shafts, which are separated into low viscosity zone, a medium high viscosity zone, and a high viscosity zone; the circular tray reactors in the high viscosity zone are single tray reactor that allow rapid disassembly; multiple scrapers are further installed on polymerization vessel walls between adjacent singular trays in the high-viscosity zone; the distance between each scraper and the adjacent trays varies, and a gradual reduction of the thickness of a high viscosity melt on the trays can be carried out; the present vessel reduces the load on a stirring motor, enhances devolatilization efficiency during polymerization, extends the operating period of a polymerization apparatus, and facilitates the cleaning of the inner walls of a reaction vessel. For the PETG / PCTG polymerization method, a proprietary germanium-based or titanium-germanium composite catalyst is utilized, and the described polymerization vessel serves as a final polymerization vessel. The polymerization vessel of the present invention can prepare high viscosity PETG or PCTG with excellent color.

Description

Polymerization kettle for high-viscosity PETG or PCTG, and polymerization method for PETG or PCTG Technical Field

[0001] The invention relates to a polymerization kettle for high-viscosity PETG or PCTG and a polymerization method for PETG or PCTG. Background Art

[0002] PETG and PCTG are both transparent, non-crystalline copolyesters. Both can be prepared through the esterification and polymerization of terephthalic acid (PTA), ethylene glycol (EG), and 1,4-cyclohexanedimethanol (CHDM) in the presence of an esterification catalyst and a polymerization catalyst. The two can be distinguished by the molar percentage of the CHDM segment relative to the total diol (CHDM and EG) segments in the copolyester. Generally, a polymer with a CHDM segment molar percentage of 31% to 32% is called PETG, while a polymer with a CHDM segment molar percentage of 60% to 62% is called PCTG. Both polymers exhibit high transparency, good toughness and impact strength, excellent low-temperature toughness, high tear resistance, good processability, and excellent chemical resistance. Both can be processed using traditional molding methods such as extrusion, injection molding, blow molding, and vacuum forming. They are widely used in the sheet and plate markets, high-performance shrink film, bottles, and profiles. They can also be used to produce toys, household utensils, and medical products.

[0003] Conventional PETG or PCTG synthesis typically utilizes a conventional horizontal polymerization kettle containing a conventional disc reactor. However, during polymerization, due to the high dynamic viscosity of the melt, the melt will climb the disc reactor, resulting in melt accumulation on the disc reactor discs. This excessive melt thickness on the reactor walls and the disc reactor slows mass transfer, hindering further polymerization. This adhered melt also places an increased load on the disc reactor's stirring motor, further reducing polymerization efficiency. Furthermore, the cleanup of the melt from the reactor and disc reactor is significantly hindered, significantly shortening the polymerization unit's operating cycle.

[0004] Moreover, for PETG or PCTG melt, in the polymer macromolecular chain segments, PETG contains 31% to 32% CHDM structural units, and PCTG contains 60% to 62% CHDM units. The rigid chain segments are combined with the cis-trans structure, and the steric hindrance is greatly increased. Therefore, the vibration and movement slip of the regional segments and chain segments of the polymer macromolecular chain are severely restricted when heated. Therefore, as the molecular weight of the polymer increases, the difficulty of the macromolecular chain movement increases rapidly. Macroscopically, it is manifested as a rapid increase in melt viscosity. It is very easy to coil under high viscosity. Moreover, because the melt elasticity is poor, it is easy to produce shear thinning under high temperature (278 to 285 ° C), and the film is very easy to break, making the polymerization reaction difficult to control. In addition, due to the slow mass transfer rate of the polymer material, the final melt viscosity is not large enough, and the color of the polymerization product PETG or PCTG is not excellent enough.

[0005] Summary of the Invention

[0006] The present invention aims to provide a high-viscosity PETG or PCTG polymerization kettle, which is used for preparing a high-viscosity PETG or PCTG melt. The high-viscosity PETG or PCTG melt prepared by the polymerization kettle has high viscosity, can significantly improve the hue and phase properties of the polymerized product while ensuring other excellent properties, and the polymerization kettle can extend the operating cycle of the polymerization device and is easy to clean.

[0007] Another object of the present invention is to provide a polymerization method for PETG or PCTG, which can produce a PETG or PCTG polymerization product with high viscosity and significantly improved hue and phase properties.

[0008] In order to achieve the above object, the technical solution adopted by the present invention is:

[0009] A polymerization kettle for preparing a PETG or PCTG melt, wherein the intrinsic viscosity of the PETG or PCTG melt is greater than 0.770, the polymerization kettle is a horizontal polymerization kettle, and comprises a main body containing a chamber therein, the main body comprising a low viscosity zone, a medium-high viscosity zone, and a high viscosity zone arranged in sequence along the axial direction of the polymerization kettle, wherein the viscosity of the PETG or PCTG melt in the low viscosity zone, the medium-high viscosity zone, and the high viscosity zone increases in sequence; the polymerization kettle further comprises two stirring shafts, one of which is arranged in the low viscosity zone and the other is arranged in the high viscosity zone. In the high viscosity zone and the medium-high viscosity zone; multiple disc reactors are arranged on the two stirring shafts, the disc reactors in the low viscosity zone are 6 to 8 groups of combined discs, each group is 3-10 discs; the disc reactors in the medium-high viscosity zone are 5 to 8 groups of double-disc or triple-disc combined discs; the disc reactors in the high viscosity zone are single discs, and the single discs are detachably arranged in the polymerization kettle; a scraper group is also arranged on the wall of the polymerization kettle between each two adjacent single discs in the high viscosity zone, and the scraper group includes multiple scrapers, and the distance between each scraper and the adjacent single disc is different.

[0010] In the present invention, PETG refers to a copolyester of terephthalic acid PTA, ethylene glycol EG, and 1,4-cyclohexanedimethanol CHDM, and in the copolyester, the chain segment corresponding to CHDM accounts for 31% to 32% by mole in the total glycol (CHDM and EG) chain segments; PCTG refers to a copolyester of terephthalic acid PTA, ethylene glycol EG, and 1,4-cyclohexanedimethanol CHDM, and in the copolyester, the chain segment corresponding to CHDM accounts for 60% to 62% by mole in the total glycol (CHDM and EG) chain segments.

[0011] In the present invention, the distance between each scraper and the adjacent monolithic disc refers to the distance from the contact position between the scraper and the polymerization reactor wall to the adjacent disc reactor.

[0012] In the present invention, the combined disc refers to two or more adjacent disc reactors fixedly connected together to form a combined disc.

[0013] In some embodiments, the disc reactor in the high viscosity zone includes a ring and a plurality of spokes arranged inside the ring, the ring includes a first part and a second part, the first part is fixedly connected to the plurality of spokes respectively, and the second part is detachably connected to the first part.

[0014] In some embodiments, the detachable connection is a threaded connection.

[0015] The threaded connection method can be, for example, to design screw holes at the ends of the first part and the second part, and the two are matched, and then the impact bolts are connected, so that the entire annular part forms a smooth integral disc, which can prevent dead corners from forming when the device is running.

[0016] In some embodiments, the plurality of spokes is 5 spokes.

[0017] In some embodiments, positioning screw holes are designed to extend left and right from the spoke top of the disc reactor in the high viscosity area, and the rings of adjacent spokes are designed as detachable segmented rings that cooperate with the screw holes at the spoke ends and are connected with impact bolts to form a smooth entire ring.

[0018] In some embodiments, the multiple scrapers are arranged vertically, with the ends of the scrapers pointing toward the axis of the stirring shaft, and the projections of the multiple scrapers on the plane where the disc reactor is located are located on the same circle.

[0019] In some embodiments, each scraper is the same length.

[0020] In some embodiments, the distance between the scraper and the adjacent previous single disk between each two adjacent monolithic disks in the high-viscosity zone is distributed in an arithmetic progression. Since the projections of the multiple scrapers on the plane of the disk reactor lie on the same circle, the scrapers are effectively installed in a spiral configuration between the two adjacent monolithic disks.

[0021] In some embodiments, in each scraper group, the distance between the first scraper and the adjacent previous single-piece disk is 30-100 mm, and the distance between the last scraper and the adjacent next single-piece disk is 30-100 mm, preferably 40-80 mm, and more preferably 50-70 mm.

[0022] In some embodiments, in each scraper set, the axial distance between each two adjacent scrapers is 15 to 25 mm, preferably 20 to 25 mm. In the present invention, the axial distance between each two adjacent scrapers refers to the distance between the projections of the two adjacent scrapers on the stirring shaft.

[0023] In some embodiments, the scraper has a wedge-shaped cross section, with the thick end of the wedge facing the rotation direction of the disc reactor.

[0024] In some embodiments, five scrapers are provided between each two adjacent monolithic discs. The number of scrapers is set to be the same as the number of spokes, facilitating quick disassembly or cleaning.

[0025] In some embodiments, the total number of disc reactors in the low viscosity zone is 30 to 45, the total number of disc reactors in the medium-high viscosity zone and the high viscosity zone is 13 to 20, the total number of disc reactors in the high viscosity zone is 8 to 12, and 8 to 12 scraper groups are provided in the high viscosity zone.

[0026] In some embodiments, the length of the low viscosity zone is half of the length of the polymerization kettle, the total length of the medium-high viscosity zone and the high viscosity zone is half of the length of the polymerization kettle; and the length ratio of the medium-high viscosity zone to the high viscosity zone is 1:2.

[0027] In the present invention, half does not refer to the exact mathematical value of half, but refers to a value approximately at or around half, and is approximately equal to half.

[0028] In some embodiments, the polymerization kettle further includes a support base fixedly disposed on the inner wall of the main body for supporting two stirring shafts.

[0029] In some embodiments, the polymerization kettle further comprises a prepolymer inlet located at the bottom of the front end of the low viscosity zone and a high viscosity melt outlet located at the bottom of the rear end of the high viscosity zone, and the high viscosity melt outlet is in a bell-mouth shape.

[0030] In some embodiments, the diameters of the single disks in the high-viscosity zone decrease from front to back, and the diameter of the last single disk in the high-viscosity zone is 90% to 92% of the diameter of the first single disk.

[0031] In some embodiments, the distance between the disc reactor and the top of the polymerization kettle is 200-300 mm.

[0032] In some embodiments, the distance between the disc reactor and the bottom of the polymerization vessel is 20 to 50 mm.

[0033] The polymerization kettle of the present invention is provided with a single-piece disc combination in the high-viscosity zone to form a controllable film-forming structure in the high-viscosity zone, and a combined progressive scraper group in the high-viscosity zone is installed on the wall of the polymerization kettle. Preferably, each group of scrapers includes five scrapers (five split blades), and more preferably, the five split blades are spirally evenly distributed and installed between two adjacent single-piece discs. Each group of scrapers starts from the first split blade from the front to the back (material advancement direction) and gradually decreases the distance between the scraper and the previous single-piece disc along the inner circle of the polymerization kettle wall to the fifth split blade from the front to the back, thereby gradually reducing the thickness of the thickened high-viscosity melt film on the rotating rising disc of the material, ensuring that the material surface on the disc is updated five times in each rotation cycle, and can complete two mixing effects at the lower two scraper split blades. Compared to existing integrated scrapers, the evenly distributed, split-type combined scraper provides more precise control over film thickness for highly viscous melts, significantly reducing scraper load. Furthermore, intermittent stressing allows gravitational settling of the highly viscous material in the center of the disc, maintaining a good devolatilization channel in the disc reactor's center. This avoids the melt flooding the scraper and clogging the central devolatilization channel under high-viscosity conditions, which can occur with existing integrated scrapers. Therefore, the specific combined progressive scraper arrangement of the present invention effectively improves devolatilization efficiency in the high-viscosity zone.

[0034] The present invention also provides a polymerization method for preparing PETG or PCTG by using the aforementioned polymerization kettle for preparing a PETG or PCTG melt, wherein the intrinsic viscosity of the PETG or PCTG is greater than 0.770. The polymerization method comprises the steps of sequentially subjecting terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol to an esterification reaction in a first esterification kettle and a second esterification kettle, and then subjecting the prepolymer to a prepolymerization reaction in a first prepolymerization kettle and a second prepolymerization kettle to obtain a prepolymer, and finally subjecting the prepolymer to a polymerization reaction in a final polymerization kettle to obtain the PETG or PCTG.

[0035] In some embodiments, the intrinsic viscosity of the PETG is 0.770-0.820, and the intrinsic viscosity of the PCTG is 0.790-0.820.

[0036] In some embodiments, the preparation method further comprises the step of adding an esterification catalyst to the first esterification kettle before the esterification reaction, wherein the esterification catalyst is selected from tetrabutyl titanate, tetraisopropyl titanate or tetra(2-ethylhexyloxy) titanate.

[0037] In some embodiments, the mass of the titanium element in the esterification catalyst accounts for 1 to 3 ppm of the mass of the PETG or PCTG.

[0038] In some embodiments, the esterification reaction in the first esterification kettle is carried out at a pressure of 70-80 kPa.

[0039] In some embodiments, the esterification reaction in the first esterification kettle is carried out at 255-257°C.

[0040] In some embodiments, the prepolymerization reaction in the first prepolymerization kettle is carried out under a vacuum degree of 9-12 kPa.

[0041] In some embodiments, the prepolymerization reaction in the first prepolymerization kettle is carried out under a vacuum degree of 9-12 kPa.

[0042] In some embodiments, the prepolymerization reaction in the first prepolymerization kettle is carried out at 258-266°C.

[0043] In some embodiments, the prepolymerization reaction in the second prepolymerization kettle is carried out under a vacuum degree of 0.9-1.3 kPa.

[0044] In some embodiments, the prepolymerization reaction in the second prepolymerization kettle is carried out at 260-267°C.

[0045] In some embodiments, the polymerization reaction in the final polymerization kettle is carried out under a vacuum degree of 100-130 Pa.

[0046] In some embodiments, the polymerization reaction in the final polymerization kettle is carried out at 265-275°C.

[0047] In some embodiments, the esterification reaction in the second esterification kettle is carried out under normal pressure.

[0048] In some embodiments, the second esterification kettle is a horizontal reactor and includes three compartments arranged in sequence from front to back. The preparation method further includes the step of injecting a polymerization catalyst into the third compartment from the front to the back of the second esterification kettle.

[0049] In some embodiments, the polymerization catalyst is selected from a germanium dioxide aqueous solution, a suspension of germanium dioxide dispersed in a mixed solvent of water and ethylene glycol, a surface-deposited supported germanium-based catalyst, and a surface-deposited supported titanium-germanium-based composite catalyst.

[0050] In some embodiments, the surface-deposited supported germanium-based catalyst and the surface-deposited supported titanium-germanium-based composite catalyst include a carrier, a supported deposition layer and an active component. The carrier is an inorganic porous material coated and modified by silicate. The supported deposition layer is located on the carrier and has a porous structure. The active component is deposited on the supported deposition layer.

[0051] In some embodiments, the surface-deposited supported germanium-based catalyst is prepared by a preparation method comprising the following steps: subjecting a suspension of a carrier, a water-soluble calcium salt, a water-soluble aluminum salt, a water-soluble zirconium salt to a precipitation reaction with a water-soluble hydroxide and a base, filtering, and calcining to form the supported deposition layer on the carrier; the base is selected from carbonates and / or bicarbonates; the specific surface area of ​​the carrier containing the supported deposition layer is greater than the specific surface area of ​​the carrier; the carrier containing the supported deposition layer is dispersed in water to obtain a suspension of the carrier containing the supported deposition layer; the suspension of the carrier containing the supported deposition layer is subjected to a hydrolysis reaction with a germanium source to obtain a catalyst precursor; the catalyst precursor is subjected to a coating reaction with a silicate and water to load an active component on the supported deposition layer to obtain a surface-deposited supported germanium-based catalyst.

[0052] In some embodiments, the surface-deposited supported titanium-germanium-based catalyst is prepared by a preparation method comprising the following steps: subjecting a suspension of a carrier, a water-soluble calcium salt, a water-soluble aluminum salt, a water-soluble zirconium salt to a precipitation reaction with a water-soluble hydroxide and a base, filtering, and calcining to form the supported deposition layer on the carrier; the base is selected from carbonates and / or bicarbonates; the specific surface area of ​​the carrier containing the supported deposition layer is greater than the specific surface area of ​​the carrier; the carrier containing the supported deposition layer is dispersed in water to obtain a suspension of the carrier containing the supported deposition layer; the suspension of the carrier containing the supported deposition layer is subjected to a hydrolysis reaction with a hydrochloric acid solution of a germanium source and a titanium source to obtain a catalyst precursor; the catalyst precursor is subjected to a coating reaction with a silicate and water to load an active component on the supported deposition layer to obtain a surface-deposited supported titanium-germanium-based composite catalyst.

[0053] In some embodiments, the inorganic porous material is selected from a combination of one or more of nanoporous alumina, nanoporous alumina-zirconia, nanoporous silica, and nanoporous barium sulfate, and has a particle size of 20 to 80 nm, preferably 25 to 60 nm, more preferably 30 to 45 nm, and a specific surface area of ​​220 to 400 m 2 / g, preferably 230-320m 2 / g.

[0054] In some embodiments, the water-soluble calcium salt, water-soluble aluminum salt, and water-soluble zirconium salt used to prepare the carrier-loaded deposition layer are respectively selected from sulfates, acetates, or chlorides of the corresponding metal elements; and / or, the water-soluble hydroxide is selected from one or both of sodium hydroxide and potassium hydroxide.

[0055] In some embodiments, the carbonate is selected from a combination of one or more of sodium carbonate, potassium carbonate, and ammonium carbonate.

[0056] In some embodiments, the bicarbonate is selected from a combination of one or more of sodium bicarbonate, potassium bicarbonate, and ammonium bicarbonate.

[0057] In some embodiments, the molar ratio of the water-soluble calcium salt, the water-soluble aluminum salt, and the water-soluble zirconium salt used to prepare the carrier-loaded deposition layer is 0.5-2.5:1.0-2.0:0.8-3.5.

[0058] In some embodiments, the water-soluble calcium salt, water-soluble aluminum salt, and water-soluble zirconium salt are added dropwise to the suspension of the carrier in the form of aqueous solutions; the water-soluble hydroxide and alkali are added dropwise to the suspension of the carrier in the form of aqueous solutions; and the preparation method controls the simultaneous addition of the two.

[0059] In some embodiments, the molar concentration of the water-soluble calcium salt in the aqueous solution is 0.1 to 3.0 mol / L.

[0060] In some embodiments, the molar concentration of the water-soluble aluminum salt in the aqueous solution is 0.5 to 2.5 mol / L.

[0061] In some embodiments, the molar concentration of the water-soluble zirconium salt in the aqueous solution is 0.1 to 3.5 mol / L.

[0062] In some embodiments, the total molar concentration of the water-soluble hydroxide and the base in the aqueous solution is 0.1 to 2.0 mol / L.

[0063] In some embodiments, when forming the supported deposition layer on the support, the precipitation reaction is performed at a pH of 10-12.

[0064] In some embodiments, the precipitation reaction time is 8-11 hours.

[0065] In some embodiments, the precipitation reaction temperature is 70-100°C.

[0066] In some embodiments, the preparation method further includes the steps of continuing to stir the suspension for 1.0-4 hours after the precipitation reaction is completed, then pressurizing it to 0.7-1.2 MPa, stirring and heating it to 180-200° C., balancing it for 2-4 hours, then rapidly releasing the pressure to normal pressure, cooling the suspension to room temperature, filtering, washing, drying, and crushing.

[0067] In some embodiments, the preparation method further includes a step of forming pores in the carrier after the precipitation reaction and before filtration; preferably, the step of forming pores in the carrier includes the steps of pressurizing and heating the reaction system after the precipitation reaction and reducing the pressure to normal pressure.

[0068] In some embodiments, the pressurized pressure is 0.7-1.2 MPa.

[0069] In some embodiments, heating to a temperature of 180-200° C. is used to decompose the carbonate hydroxide generated by the precipitation reaction, thereby increasing the specific surface area of ​​the carrier.

[0070] In some embodiments, when forming the supported deposition layer on the support, the temperature of the heat treatment is 290-310°C.

[0071] In some embodiments, the heating treatment time is 2-6 hours.

[0072] In some embodiments, the supported deposited layer is further dehydrated and made porous, and the specific surface area of ​​the supported powder containing the supported deposited layer after treatment is 600 to 900 m 2 / g, and the powder particle size is 20-50nm, and a large number of nanopores are formed on the powder surface.

[0073] In some embodiments, the germanium source is selected from one or both of germanium tetrachloride and tetraethylgermanium.

[0074] In some embodiments, the silicate is selected from a combination of one or more of tetraethyl silicate, tetrabutyl silicate, and tetrapropyl silicate.

[0075] In some embodiments, the germanium source is added dropwise to the suspension of the support containing the supported deposition layer to perform a hydrolysis reaction.

[0076] In some embodiments, the mass ratio of the silicate to the germanium source is 1:0.2-0.5.

[0077] In some embodiments, the surface-deposited supported germanium-based catalyst has a mass ratio of effective germanium in the support, supported deposited layer, and active component of 72.5-87.5:7.5-12.5:5.0-15.0. In the present invention, the effective germanium in the active component refers to the amount of germanium in the active component calculated by converting the germanium element in the active component to germanium dioxide on an equimolar basis.

[0078] In some embodiments, the preparation method further includes preparing a surface-deposited supported germanium-based catalyst in ethylene glycol under stirring conditions to form a suspension with a mass concentration of 10%-20%, stirring evenly, grinding and filtering to prepare a catalyst suspension, wherein the catalyst suspension has an effective germanium element content (as germanium dioxide) of 1.0% to 3.0%, and is a stable suspension that can be stored for 3.0 to 5.0 months without sedimentation.

[0079] For germanium-based catalysts, in some embodiments, the preparation method further includes the steps of filtering, washing, and drying after loading the active component on the loaded deposition layer, and the loaded catalyst is in a powder state; preferably, the effective germanium content in the powdered loaded catalyst is 5.0% to 15.0%.

[0080] For titanium-germanium based catalysts, in some embodiments, the preparation method further includes the steps of filtering, washing, and drying after loading the active component on the loaded deposition layer, and the loaded catalyst is in a powder state; preferably, the loaded catalyst in the powder state has an effective germanium content of 2.5% to 7.5%, and an effective titanium content of 0.6% to 1.9%.

[0081] In some embodiments, the germanium source is selected from one or both of germanium tetrachloride and tetraethylgermanium.

[0082] In some embodiments, the titanium source is selected from a combination of one or more of tetraisopropyl titanate, tetrabutyl titanate, and titanium tetrachloride.

[0083] In some embodiments, the silicate is selected from a combination of one or more of tetraethyl silicate, tetrabutyl silicate, and tetrapropyl silicate.

[0084] In some embodiments, a hydrochloric acid solution of a germanium source and a titanium source are added dropwise to the suspension of the support containing the supported deposition layer to perform a hydrolysis reaction.

[0085] In some embodiments, the ratio of the mass of the silicate to the total mass of the germanium source and the titanium source is 1:0.2-0.5.

[0086] For titanium-germanium catalysts, in some embodiments, the mass ratio of the support, supported deposited layer, and effective germanium to effective titanium in the active component in the surface-deposited supported titanium-germanium-based catalyst is 78.1-89.4:7.5-12.5:2.5-7.5 (based on germanium dioxide):0.6-1.9 (based on titanium dioxide). In the present invention, effective titanium refers to the titanium element in the active component calculated as titanium dioxide on an equimolar basis.

[0087] In some embodiments, the molar ratio of titanium to germanium in the active component is 1:1.5 to 4.5.

[0088] For germanium-based catalysts, in some embodiments, the preparation method further includes the steps of filtering, washing, and adding a mixed solvent of water and ethylene glycol to disperse after loading the active component on the supported deposition layer, and the supported catalyst is in a suspension state.

[0089] For titanium-germanium based catalysts, in some embodiments, the preparation method further comprises the steps of filtering, washing, and adding a mixed solvent of water and ethylene glycol to disperse after loading the active component on the supported deposition layer, and the supported catalyst is in a suspension state.

[0090] In some embodiments, the particle size of the supported germanium-based catalyst and the titanium-germanium-based composite catalyst are both 60 to 150 nm; and the specific surface area is 100 to 280 m 2 / g, the catalyst particle size is between nanometers and sub-nanometers, and the catalytic active centers on the catalyst particle surface can fully contact with oligomers in nanometer state, thereby improving the efficiency of the polymerization catalytic reaction.

[0091] When preparing the aforementioned surface-deposited nano-supported germanium-based or titanium-germanium-based catalyst, a load deposition layer is first prepared on the carrier through a co-precipitation reaction of metal salts such as calcium, aluminum, and zirconium. The load deposition layer is a basic carbonate of three metals and provides a load deposition site for the active component. After calcination, the basic carbonate decomposes carbon dioxide gas, so that the load deposition layer has a porous structure, and the specific surface area of ​​the layer is greater than the specific surface area of ​​the carrier. That is, the present invention expands the specific surface area of ​​the carrier by precipitating a load deposition layer on the carrier, and at the same time, the carrier has more microporous structures, which is more conducive to the effective loading of the active component. Among them, the zirconium element in the load deposition layer can increase the strength of the carrier, and the calcium element and the aluminum element are conducive to forming the porous structure of the load deposition layer. When used to catalyze the synthesis of PETG or PCTG polyester, the in-situ deposited germanium element or the composite element of germanium and titanium element has a larger specific surface area, which can obtain better catalytic activity and reaction efficiency.

[0092] In some embodiments, the polymerization catalyst is selected from a germanium dioxide aqueous solution or a suspension of germanium dioxide dispersed in a mixed solvent of water and ethylene glycol, and the mass of germanium dioxide in the polymerization catalyst accounts for 100-150 ppm of the mass of PETG or PCTG.

[0093] In some embodiments, the polymerization catalyst is selected from a surface-deposited supported germanium-based catalyst, and the mass of the germanium element (calculated as germanium dioxide) in the polymerization catalyst accounts for 50 to 75 ppm of the mass of PETG or PCTG, preferably 40 to 90 ppm; more preferably 50 to 75 ppm.

[0094] In some embodiments, the polymerization catalyst is selected from the surface-deposited supported titanium-germanium based composite catalyst, and the mass of the titanium element and the germanium element (calculated as germanium dioxide) in the polymerization catalyst accounts for 8-12 ppm and 25-50 ppm of the mass of PETG or PCTG.

[0095] In some embodiments, the polymerization method further comprises the steps of pre-melting 1,4-cyclohexanedimethanol and transferring the melted 1,4-cyclohexanedimethanol to the first esterification kettle.

[0096] In some embodiments, the polymerization kettle further includes steam feed ports for introducing superheated ethylene glycol steam, which are arranged at the top of the main body at the rear end of the low viscosity zone, the rear end of the medium and high viscosity zone, and the rear end of the high viscosity zone. The polymerization method further includes a step of using a metering system to meter the superheated ethylene glycol steam and introducing it into the final polymerization kettle.

[0097] In some embodiments, when preparing PETG, the molar ratio of terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol is 1: 0.92-0.93: 0.325-0.315; or, when preparing PCTG, the molar ratio of terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol is 1: 0.63-0.64: ​​0.610-0.615.

[0098] The present invention also provides PETG or PCTG prepared by the polymerization method of PETG or PCTG.

[0099] In some embodiments, the intrinsic viscosity of the PETG is 0.780-0.820 (phenol:tetrachloroethane 3:2).

[0100] In some embodiments, the PETG has a hue L value of ≥62.0 and a b value of ≤1.0, and has high chroma.

[0101] In some embodiments, the intrinsic viscosity of the PCTG is 0.800-0.820 (phenol:tetrachloroethane 3:2).

[0102] In some embodiments, the PCTG has a hue L value of ≧62.0 and a b value of ≦1.0, and has high chroma.

[0103] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0104] The polymerization kettle of the present invention is designed to quickly disassemble a single disk in the high-viscosity area and is equipped with a combined progressive scraper group, which can gradually reduce the thickness of the high-viscosity melt on the disk, greatly reduce the load of the stirring motor, and improve the polymerization reaction efficiency. In particular, its detachable design greatly facilitates the manufacture of the reactor, overhaul of the device and cleaning of the inner wall of the reactor.

[0105] A detachable single-piece disc is provided in the high-viscosity area of ​​the polymerization kettle, which is matched with a combined progressive split scraper group, thereby greatly reducing the difficulty of installing the internal parts of the final polymerization kettle. In addition, a gel carbonization layer is easily formed in the upper part of the polymerization kettle during the operation of the final polymerization kettle. When using a conventional disc reactor for high-pressure cleaning of the reactor, it is difficult to clean due to the small space. The detachable single-piece disc of the present invention can remove the detachable part, which greatly facilitates the construction operation.

[0106] By adopting the polymerization kettle of the present invention, PTEG or PCTG can be polymerized at a relatively low temperature (260-270°C). At this relatively low temperature, the PETG or PCTG melt has a higher dynamic viscosity, and the two high-viscosity melts can be evenly adhered to the disc reactor. At the same time, by designing a combined progressive scraper, the film-forming melt on the disc reactor disk surface can be cut to control the film thickness and improve the polymerization efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0107] FIG1 is a schematic structural diagram of a final polymerization reactor used in the embodiment;

[0108] FIG2 is a schematic diagram of a disc reactor in the high viscosity zone of the final polymerization reactor;

[0109] FIG3 is a schematic diagram of multiple disc reactors in the high viscosity zone of the final polymerization reactor;

[0110] FIG4 is a schematic diagram of the projection of the scraper in the high viscosity zone of the final polymerization kettle on the disc reactor;

[0111] Figure 5 is a schematic diagram of the scraper structure in the high viscosity area of ​​the final polymerization reactor;

[0112] FIG6 is a perspective schematic diagram of the scraper structure in the high viscosity area of ​​the final polymerization reactor;

[0113] FIG7 is another perspective schematic diagram of the scraper structure in the high viscosity area of ​​the final polymerization reactor;

[0114] Among them, 1-low viscosity area, 2-medium and high viscosity area, 3-high viscosity area, 4-scraper, 5-ring, 6-first part, 7-second part, 8-spoke, 9-disc reactor, 10-stirring shaft, 11-support seat, 12-positioning screw hole. DETAILED DESCRIPTION

[0115] The above scheme is further described below with reference to specific examples. It should be understood that these examples are intended to illustrate the basic principles, main features, and advantages of the present invention, and the present invention is not limited in scope by the following examples. The implementation conditions used in the examples can be further adjusted according to specific requirements. The implementation conditions not specified are generally those used in routine experiments. Unless otherwise specified in the following examples, all raw materials were purchased commercially or prepared by conventional methods in the art.

[0116] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the contents of the present invention and implement them accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent changes or modifications made in accordance with the spirit of the present invention are intended to be covered by the scope of protection of the present invention.

[0117] The present invention will be further described below in conjunction with the accompanying drawings and preferred embodiments of the present invention. In the following embodiments, it should be noted that the "front" and "rear" directions in the terms are based on the flow direction of the material, and the direction in which the material flows first is the front, and the direction in which the material flows later is the rear. For example, in Figure 1, the "front" in the term refers to the right side in Figure 1, and the "rear" in the term refers to the left side in Figure 1. Therefore, the directions and positional relationships described in the present invention are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, only have a specific direction, be constructed and operated in a specific direction, and therefore should not be understood as limiting the present invention.

[0118] As shown in Figures 1-7, the polymerization kettle for preparing a PETG or PCTG melt of the present invention is a horizontal polymerization kettle and includes a main body containing a chamber therein, the main body including a low viscosity area 1, a medium-high viscosity area 2, and a high viscosity area 3 arranged in sequence along the axial direction of the polymerization kettle, and the viscosity of the PETG or PCTG melt in the low viscosity area 1, the medium-high viscosity area 2, and the high viscosity area 3 increases in sequence; the polymerization kettle also includes two stirring shafts 10, one of which is arranged in the low viscosity area 1, and the other stirring shaft 10 is arranged in the high viscosity area 3 and the medium-high viscosity area 2; the two stirring shafts 10 are arranged in the low viscosity area 1, and the other stirring shaft 10 is arranged in the high viscosity area 3 and the medium-high viscosity area 2; A plurality of disc reactors 9 are arranged on each stirring shaft 10. The disc reactors 9 in the low-viscosity zone 1 are composed of 6 to 8 groups of combined discs, with each group consisting of 3 to 10 discs. The disc reactors 9 in the medium- and high-viscosity zone 2 are composed of 5 to 8 groups of double- or triple-disc combined discs. The disc reactors 9 in the high-viscosity zone 3 are single discs, which are detachably arranged in the polymerization kettle. A scraper group is also arranged on the wall of the polymerization kettle between each adjacent two single discs in the high-viscosity zone 3. The scraper group includes multiple scrapers 4, and the distance between each scraper 4 and the adjacent single disc is different.

[0119] The distance between each scraper 4 and the adjacent monolithic disc refers to the distance from the contact position of the scraper 4 with the polymerizer wall to the adjacent disc reactor 9 .

[0120] As shown in Figures 2-5, the disc reactor 9 in the high viscosity zone 3 includes a ring 5 and a plurality of spokes 8 disposed inside the ring 5. The ring 5 includes a first portion 6 and a second portion 7. The first portion 6 is fixedly connected to the plurality of spokes 8, and the second portion 7 is detachably connected to the first portion 6. The detachable connection may be a threaded connection.

[0121] The threaded connection method can be, for example, to design screw holes at the ends of the first part 6 and the second part 7, and the two are matched, and then the impact bolts are connected, so that the entire ring 5 part forms a smooth integral disc, which can prevent dead corners from forming when the device is running.

[0122] As shown in Figure 2-3, the spokes 8 of the disc reactor 9 in the high viscosity area are designed with positioning screw holes 12 extending to the left and right of the top, and the rings 5 ​​of the adjacent spokes 8 are designed with detachable segmented rings 5, which cooperate with the positioning screw holes 12 at the ends of the spokes 8 and are connected with impact bolts to form a smooth entire ring 5.

[0123] As shown in Figures 6-7, the multiple scrapers 4 are arranged vertically, the ends of the scrapers 4 point to the axis of the stirring shaft 10, and the projections of the multiple scrapers 4 on the plane where the disc reactor 9 is located are located on the same circle.

[0124] Each scraper 4 has the same length. Between each pair of adjacent monolithic discs in the high-viscosity zone 3, the distance between a scraper 4 and the preceding disc follows an arithmetic progression. Since the projections of the multiple scrapers 4 onto the plane of the disc reactor 9 lie on the same circle, the scrapers 4 are effectively installed in a spiral configuration between the adjacent monolithic discs.

[0125] In each set of scrapers (4), the distance between the first scraper (4) and the adjacent preceding monolithic disk is 30-100 mm, and the distance between the last scraper (4) and the adjacent succeeding monolithic disk is 30-100 mm, preferably 40-80 mm, and more preferably 50-70 mm. In each set of scrapers (4), the axial distance between each pair of adjacent scrapers (4) is 15-25 mm, preferably 20-25 mm. The scrapers (4) have a wedge-shaped cross-section, with the thick end of the wedge facing the direction of rotation of the disc reactor 9.

[0126] The plurality of spokes 8 are 5 spokes 8. Five scrapers 4 are provided between every two adjacent monolithic discs. The number of scrapers 4 is the same as the number of spokes 8, for the purpose of rapid disassembly or cleaning.

[0127] As shown in Figure 1, the total number of disc reactors 9 in low-viscosity zone 1 is 30 to 45, the total number of disc reactors 9 in medium-high viscosity zone 2 and high viscosity zone 3 is 13 to 20, and the total number of disc reactors 9 in high viscosity zone 3 is 8 to 12. The high viscosity zone is equipped with 4 to 12 groups of scrapers. The length of low-viscosity zone 1 is half the length of the polymerization kettle, and the combined length of medium-high viscosity zone 2 and high viscosity zone 3 is half the length of the polymerization kettle. The length ratio of medium-high viscosity zone 2 to high viscosity zone 3 is 1:2.

[0128] The polymerization kettle further includes a support base 11 fixedly arranged on the inner wall of the main body for supporting two stirring shafts 10.

[0129] The polymerization kettle further comprises a prepolymer inlet located at the front bottom of the low viscosity zone 1 and a high viscosity melt outlet located at the rear bottom of the high viscosity zone 3, and the high viscosity melt outlet is in a bell-mouth shape.

[0130] The diameter of the discs in high-viscosity zone 3 decreases from front to back, with the diameter of the last disc in high-viscosity zone 3 being 90% to 92% of the diameter of the first disc. The distance between the disc reactor 9 and the top of the polymerization kettle is 200 to 300 mm, and the distance between the disc reactor 9 and the bottom of the polymerization kettle is 20 to 50 mm.

[0131] The polymerization device of the present invention may also include a CHDM melt conveying system, a slurrying system, a catalyst synthesis and preparation system, a composite stabilizer preparation system, an EG recovery system, a colorant preparation system, and a melt pump post-additive injection system (for example, adding antioxidants, lubricants, anti-UV masterbatch, etc.).

[0132] Example 1

[0133] This embodiment provides a polymerization method for PETG or PCTG. The high-viscosity final polymerization kettle used in the polymerization method adopts the aforementioned structure. The specific steps of the polymerization method are as follows:

[0134] PETG polymerization:

[0135] Continuous polymerization is carried out on a 30,000 tons / year PETG continuous polymerization unit, which includes a first esterification kettle, a second esterification kettle (three-chamber structure), a first prepolymerization kettle, a second prepolymerization kettle, and a high-viscosity final polymerization kettle.

[0136] First, purified terephthalic acid (PTA), ethylene glycol (EG) and molten 1,4-cyclohexanedimethanol (CHDM) were added in a molar ratio of PTA:EG:CHDM = 1:0.93:0.32 (where EG is an excess feed ratio, and all CHDM enters the corresponding segments in the copolyester, and the molar percentage of the segments corresponding to CHDM in the total segments of the diol is 32%), with a total molar ratio of PTA:(EG+CHDM) = 1:1.25. The slurry was accurately measured and tetrabutyl titanate was injected into the slurry delivery pipeline as an esterification catalyst, accounting for 3ppm of the total mass of the melt (in terms of titanium element). The prepared slurry is transported to the first esterification kettle via a screw metering pump, and the temperature in the first esterification kettle is controlled at 254-255°C, and the process tower pressure is 70-80kPa (positive pressure). The second esterification kettle is a multi-chamber design with three sub-chambers, which is convenient for adding various additives. A germanium dioxide aqueous solution is added to the second chamber of the second esterification kettle (which is prepared by the following method: adding germanium dioxide powder to distilled water, performing a reflux reaction, and reacting for 8-10 hours to allow germanium dioxide to react with water to form germanic acid. The mass concentration of germanium dioxide is 0.8%) as a polymerization catalyst (addition in the second chamber is conducive to evaporating the catalyst). Water), the polymerization catalyst accounts for 120ppm of the total mass of the melt (calculated as germanium dioxide), the second esterification kettle three chambers add toner and stabilizer (phosphate, etc.), the second esterification kettle is a normal pressure reactor, the esterification temperatures of the three chambers are controlled as follows: 255-256°C for the first chamber, 253-254°C for the second chamber, and 257-258°C for the third chamber; the esterified material after the esterification reaction is completed is introduced into the first prepolymerization kettle, the first prepolymerization kettle is a vertical stirring structure with an inner and outer chamber design, the reaction temperature of the first prepolymerization kettle is controlled at 258-260°C, the vacuum degree is 9.0Kpa, and the oligomers polymerized in the first prepolymerization kettle are introduced into the second prepolymerization kettle. The polymerization kettle and the second prepolymerization kettle are uniaxial horizontal disc reactors. The reaction temperature of the second prepolymerization kettle is controlled at 260-262°C. The prepolymer after the reaction in the second prepolymerization kettle is introduced into the high-viscosity final polymerization kettle via a prepolymer melt pump and a prepolymer filter. The high-viscosity final polymerization reactor adopts the aforementioned specific structure, and its reactor outlet temperature is controlled at 265-268°C, the vacuum degree is 80-110 Pa, the outlet melt dynamic viscosity is controlled at 635-650 Pa.s, and the outlet PETG intrinsic viscosity is controlled at 0.781 (measured in a mixed solvent of phenol and tetrachloroethane with a volume ratio of 3:2). The PETG chip indicators are shown in Table 1 below. In the present invention, all melt chip properties are tested according to the GB / T 14190-2017 standard, where the intrinsic viscosity is measured in a mixed solvent of phenol and tetrachloroethane with a volume ratio of 3:2. The moisture, ash, iron, and agglomerated particles refer to the mass fractions of water, ash, Fe element, and agglomerated particles in the polyester, respectively.

[0137] Or PCTG polymerization:

[0138] Continuous polymerization is carried out on a 30,000 ton / year PCTG continuous polymerization unit, which includes a first esterification kettle, a second esterification kettle (three-chamber structure), a first prepolymerization kettle, a second prepolymerization kettle, and a high-viscosity final polymerization kettle.

[0139] First, purified terephthalic acid (PTA), ethylene glycol (EG), and molten 1,4-cyclohexanedimethanol (CHDM) were mixed in a molar ratio of PTA:EG:CHDM = 1:0.63:0.63 (where EG is an excess feed ratio, and the molar percentage of the CHDM corresponding segment in the copolyester is 62%), with a total molar ratio of PTA:(EG+CHDM) = 1:1.26. The slurry was accurately measured and tetrabutyl titanate was injected into the slurry conveying pipeline as an esterification catalyst, with a mass dosage of 3 ppm (in terms of titanium element) accounting for the total mass of the melt. The prepared slurry was conveyed to the first esterification kettle via a screw metering pump. The temperature in the first esterification kettle was controlled at 256-257°C, and the process tower pressure was 70-80 kPa (positive pressure). The second esterification kettle was a multi-chamber design with three compartments for easy addition of various additives. In the second chamber of the second esterification kettle, a germanium dioxide aqueous solution (the preparation method is the same as above. The mass concentration of germanium dioxide is 0.8%) is added as a polymerization catalyst (addition in the second chamber is conducive to evaporating the water in the catalyst). The polymerization catalyst accounts for 120ppm (calculated as germanium dioxide) of the total mass of the melt. Toner and stabilizer (phosphate ester, etc.) are added to the third esterification chamber. The second esterification kettle is a normal pressure reactor. The esterification temperatures of the three chambers are controlled as follows: 255-256°C in the first chamber, 253-254°C in the second chamber, and 260-262°C in the third chamber. The esterified material after the esterification reaction is completed is introduced into the first prepolymerization kettle. The first prepolymerization kettle has a vertical stirring structure with an inner and outer chamber design. The reaction temperature of the first prepolymerization kettle is controlled at 266-268°C. Vacuum degree: 9.0KPa, the oligomer polymerized in the first prepolymerization kettle is introduced into the second prepolymerization kettle, the second prepolymerization kettle is a single-axis horizontal disc reactor, and the reaction temperature of the second prepolymerization kettle is controlled at 272-274°C. The prepolymer after the reaction in the second prepolymerization kettle is introduced into the high-viscosity final polymerization kettle through a prepolymer melt pump and a prepolymer filter. The high-viscosity final polymerization reactor is a front and rear double-axis horizontal disc reactor, and its reactor outlet temperature is controlled at 280-282°C, vacuum degree: 90-110Pa, outlet melt dynamic viscosity is controlled at 600-620Pa.s, and outlet PCTG intrinsic viscosity is controlled at 0.801 (measured in a mixed solvent of phenol: tetrachloroethane with a volume ratio of 3:2). The PCTG slice indicators are shown in Table 2 below.

[0140] Example 2

[0141] This embodiment provides a polymerization method for PETG or PCTG. The high-viscosity final polymerization reactor employed in the polymerization method adopts the aforementioned structure. The specific steps of the polymerization method are substantially the same as those of Example 1, with the only difference being that the polymerization catalyst is first vacuum distilled from a germanium dioxide aqueous solution. After half of the total water mass is distilled off, an equal mass of fresh ethylene glycol (EG) is added under stirring to prepare a solution in which germanium dioxide is dispersed in a mixed solvent of water and ethylene glycol. The mass concentration of germanium dioxide is also 0.8%, and the mass ratio of water to ethylene glycol is 1:1. The polymerization results are shown in Tables 1-2 below.

[0142] Example 3

[0143] This embodiment provides a polymerization method for PETG or PCTG. The high-viscosity final polymerization reactor used in the polymerization method adopts the aforementioned structure. The specific steps of the polymerization method are basically the same as those in Example 1, with the only difference being that the polymerization catalyst is replaced by a surface-deposited supported germanium-based catalyst (the carrier is nanoporous barium sulfate) instead of a germanium dioxide aqueous solution.

[0144] The preparation method of the catalyst is specifically as follows:

[0145] 1) Ethylene glycol is heated to 50° C., and accurately measured barium hydroxide octahydrate is slowly added to the reactor under high-speed stirring conditions (high-speed homogenizer: speed: 3000-6000 rpm) and stirred until completely dissolved. Then, 10% mass concentration of dilute sulfuric acid is quickly added to the reactor according to the molar ratio of barium ions, and high-speed stirring is maintained for 1.0 hour. The reaction heat causes the suspension to be heated to about 90° C., and the pH of the suspension is adjusted to be stable at 7.0. The suspension is then heated and refluxed to evaporate water, and the temperature is lowered to 170° C. Ethylene glycol is then added to make the mass content of barium sulfate powder 20%, and then stirred for 0.5 hour. The pH value is measured again until the pH value of the suspension is completely stable at 7.0. The obtained barium sulfate powder has a particle size of 20 nm and a specific surface area of ​​350 m 2 / g.

[0146] 2) Tetraethyl silicate and sodium hydroxide were added dropwise to a pH 7.0 suspension of barium sulfate in ethylene glycol to coat the barium sulfate powder with a silicon dioxide layer. After aging for 6 hours, a pre-prepared mixed aqueous solution of calcium chloride, aluminum chloride, and zirconium acetate (wherein the molar concentration of calcium chloride was 2.5 mol / L, the molar concentration of aluminum chloride was 0.5 mol / L, and the molar concentration of zirconium acetate was 0.8 mol / L) and a mixed aqueous solution of sodium hydroxide and sodium bicarbonate with a total molar concentration of 0.5 mol / L were simultaneously added dropwise to the reactor under high-speed stirring, in amounts such that the total valence of the three metal ions was equal to the total valence of the hydroxide and carbonate ions. The pH of the suspension was strictly controlled to be between 10.0 and 10.2 during the addition process. The addition time was controlled to 11 hours and the reaction temperature was controlled to 80°C to allow the three metals to deposit on the support surface. The obtained suspension was stirred and aged for 1.0 hour, then stirred under pressure (the pressure was 0.7 MPa) and heated to 180°C at the same time. After equilibration for 2.0 hours, the pressure was quickly released to normal pressure, and the suspension was cooled to room temperature. After filtering, washing, drying and crushing with an ultrafine grinder, the suspension was placed in a muffle furnace for calcination at a temperature of 290°C for 6 hours. The metal basic carbonate deposited on the surface of the carrier was dehydrated and made porous, so that a loaded deposition layer with a porous structure was formed on the surface of the carrier. The specific surface area of ​​the carrier containing the loaded deposition layer is 600 to 900 m 2 / g.

[0147] 3) The carrier containing the loaded deposition layer obtained in step 2) is added with distilled water under stirring to prepare a suspension with a mass percentage of 20%. After grinding the suspension twice with an ultrafine grinder, the suspension is heated to 90°C. A certain amount of germanium tetrachloride is slowly added dropwise to the above suspension under stirring over 4.0 hours. The germanium tetrachloride and water undergo a hydrolysis reaction to generate germanium dioxide, which is deposited on the surface of the loaded deposition layer. During the dropwise addition, the pH of the suspension is adjusted with sodium hydroxide so that the pH is maintained between 10.0 and 10.2. After the dropwise addition is completed, the suspension is stirred and aged for 1.5 hours at 90°C, and then a certain amount of silicate is slowly added dropwise to the suspension over 2.0 hours. After the dropwise addition is completed, the suspension is aged for another 1.0 hour to obtain a suspension of the catalyst. The mass ratio of silicate to germanium tetrachloride is 1:0.2.

[0148] 4) The catalyst suspension is filtered, washed with distilled water, dried, and crushed to obtain a supported germanium-based catalyst powder, which can be directly packaged and stored. When used in a polymerization reaction, the powder is dispersed in ethylene glycol to obtain a suspension, in which the mass percentage of the catalyst powder is 20%. The specific surface area of ​​the catalyst powder is 280 m 2 / g, with a particle size of 100nm. In the catalyst powder, the mass ratio of effective germanium in the carrier, the supported deposition layer, and the active component is 72.5:7.5:5.0.

[0149] The aggregation results are shown in Table 1-2 below.

[0150] Example 4

[0151] This embodiment provides a polymerization method for PETG or PCTG. The high-viscosity final polymerization kettle used in the polymerization method adopts the aforementioned structure. The specific steps of the polymerization method are basically the same as those in Example 3, except that the polymerization catalyst carrier is different. Specifically, when preparing the polymerization catalyst, step 1) is not performed, and the ethylene glycol suspension of barium sulfate with a pH value of 7.0 in step 2) is replaced with an aqueous suspension of γ-nanoporous alumina with a pH value of 7.0, wherein the particle size of the γ-nanoporous alumina is 35 nm and the specific surface area is 240 m 2 / g.

[0152] The aggregation results are shown in Table 1-2 below.

[0153] Example 5

[0154] This embodiment provides a polymerization method for PETG or PCTG. The high-viscosity final polymerization kettle used in the polymerization method adopts the aforementioned structure. The specific steps of the polymerization method are basically the same as those in Example 3, except that the polymerization catalyst carrier is different. Specifically, when preparing the polymerization catalyst, step 1) is not performed, and the ethylene glycol suspension of barium sulfate with a pH value of 7.0 in step 2) is replaced with an aqueous suspension of nanoporous alumina-zirconia powder with a pH value of 7.0. The nanoporous alumina-zirconia powder has a particle size of 60 nm and a specific surface area of ​​300 m 2 / g.

[0155] The aggregation results are shown in Table 1-2 below.

[0156] Example 6

[0157] This embodiment provides a polymerization method for PETG or PCTG. The high-viscosity final polymerization reactor used in the polymerization method adopts the aforementioned structure. The specific steps of the polymerization method are basically the same as those in Example 1, except that the polymerization catalyst is replaced by a surface-deposited supported germanium-based catalyst (the support is nanoporous barium sulfate) with a surface-deposited supported titanium-germanium-based composite catalyst (the support is nanoporous barium sulfate).

[0158] The preparation method of this catalyst is essentially the same as that of Example 3, except that a titanium source and a germanium source are simultaneously added in step 3) during the preparation of the catalyst. Step 3) is specifically as follows: the carrier containing the supported deposit layer obtained in step 2) is added to distilled water under stirring to form a 20% by weight suspension. The suspension is ground twice using an ultrafine grinder, and then the suspension is heated to 90°C. A certain amount of a dilute hydrochloric acid solution of germanium tetrachloride and a certain amount of tetrabutyl titanate are simultaneously and dropwise added to the suspension under stirring over 4.0 hours. The germanium tetrachloride and water undergo hydrolysis to produce germanium dioxide, and the tetrabutyl titanate undergoes hydrolysis to produce titanium dioxide. Both are deposited on the surface of the supported deposit layer. During the addition, the pH of the suspension is adjusted with sodium hydroxide to maintain a pH between 10.0 and 10.2. After the addition was complete, the suspension was stirred and aged at 90°C for 1.5 hours. A certain amount of silicate was then slowly added to the suspension over 2 hours. After the addition was complete, the suspension was aged for another 1 hour to obtain a catalyst suspension. The ratio of the silicate mass to the combined mass of germanium tetrachloride and tetrabutyl titanate was 1:0.2. The molar ratio of tetrabutyl titanate to germanium tetrachloride was 1:1.5.

[0159] The specific surface area of ​​the catalyst powder obtained in step 4) is 280m 2 / g, with a particle size of 100 nm. In the catalyst powder, the mass ratio of the support, the supported deposited layer, the effective germanium in the active component, and the effective titanium in the active component is 78.1:7.5:2.5:1.25. The EG catalyst suspension obtained in step 4) is a stable suspension that can be stored for 5 months without sedimentation.

[0160] The aggregation results are shown in Table 1-2 below.

[0161] Example 7

[0162] This embodiment provides a polymerization method for PETG or PCTG. The high-viscosity final polymerization kettle used in the polymerization method adopts the aforementioned structure. The specific steps of the polymerization method are basically the same as those in Example 6, with the only difference being that the polymerization catalyst is replaced by a surface-deposited supported titanium-germanium-based composite catalyst (the support is nanoporous barium sulfate) with a surface-deposited supported titanium-germanium-based composite catalyst (the support is γ-nanoporous alumina powder). Step 1) is not performed when preparing the catalyst, and the ethylene glycol suspension of barium sulfate with a pH value of 7.0 in step 2) is replaced with an aqueous suspension of γ-nanoporous alumina with a pH value of 7.0, wherein the particle size of the γ-nanoporous alumina is 35 nm and the specific surface area is 240 m 2 / g.

[0163] The aggregation results are shown in Table 1-2 below.

[0164] Example 8

[0165] This embodiment provides a polymerization method for PETG or PCTG. The high-viscosity final polymerization kettle used in the polymerization method adopts the aforementioned structure. The specific steps of the polymerization method are basically the same as those in Example 6, with the only difference being that the polymerization catalyst is replaced by a surface-deposited supported titanium-germanium-based composite catalyst (the carrier is nanoporous barium sulfate) with a surface-deposited supported titanium-germanium-based composite catalyst (the carrier is nanoporous alumina-zirconia powder). Step 1) is not performed when preparing the catalyst, and the ethylene glycol suspension of barium sulfate with a pH value of 7.0 in step 2) is replaced with an aqueous suspension of nanoporous alumina-zirconia powder with a pH value of 7.0, wherein the particle size of the nanoporous alumina-zirconia powder is 60 nm and the specific surface area is 300 m 2 / g.

[0166] The aggregation results are shown in Table 1-2 below.

[0167] Comparative Example 1

[0168] This comparative example provides a polymerization method for PETG or PCTG. The high-viscosity final polymerization kettle used in this polymerization method is a conventional horizontal front-to-back biaxial polymerization kettle. The front-to-back biaxial arrangement and the disc reactor arrangement within the polymerization kettle are the same as those of the polymerization kettle described above. A scraper is also provided between each adjacent disc reactor in the high-viscosity zone, but the scraper is integrally provided on the wall of the polymerization kettle, rather than being provided with multiple separate scrapers. The specific steps of the polymerization method in Comparative Example 1 are the same as those in Example 1. The polymerization results are shown in Tables 1-2 below.

[0169] The polyester melts obtained in each embodiment and comparative example were sliced, and various properties of the slices were tested using the GB / T 14190-2017 standard. The results are shown in Tables 1-2 below, where IV refers to intrinsic viscosity, which is measured in a mixed solvent of phenol and tetrachloroethane in a volume ratio of 3:2. DEG, H2O, ash, Fe, and agglomerated particles refer to the mass fractions of diethylene glycol, water, ash, Fe element, and agglomerated particles in the polyester, respectively.

[0170] Table 1 Physical and chemical indicators of PETG

[0171] Table 2 Physical and chemical indicators of PCTG

[0172] As can be seen, the specific high-viscosity polymerization kettle of the present invention can produce a high-viscosity PETG or PCTG melt. Furthermore, while ensuring excellent other properties, the hue and color properties of the polymerized product can be significantly improved. Furthermore, the polymerization kettle can extend the operating cycle of the polymerization apparatus and is easy to clean.

[0173] The above embodiments are intended only to illustrate the technical concepts and features of the present invention. Their purpose is to enable those skilled in the art to understand the present invention and implement it accordingly. They are not intended to limit the scope of protection of the present invention. Any equivalent variations or modifications based on the spirit and essence of the present invention are intended to be encompassed by the scope of protection of the present invention.

Claims

1. A polymerization kettle for preparing a PETG or PCTG melt having an intrinsic viscosity of 0.770 or more, characterized in that: The polymerization kettle is a horizontal polymerization kettle and includes a main body containing a chamber therein. The main body includes a low-viscosity zone, a medium-high-viscosity zone, and a high-viscosity zone arranged in sequence along the axial direction of the polymerization kettle. The viscosity of the PETG or PCTG melt in the low-viscosity zone, the medium-high-viscosity zone, and the high-viscosity zone increases in sequence; the polymerization kettle also includes two stirring shafts, one of which is arranged in the low-viscosity zone, and the other is arranged in the high-viscosity zone and the medium-high-viscosity zone; multiple disc reactors are arranged on the two stirring shafts, the disc reactor in the low-viscosity zone is 6 to 8 groups of combined discs, each group has 3 to 10 discs; the disc reactor in the medium-high-viscosity zone is 5 to 8 groups of double-disc or triple-disc combined discs; the disc reactor in the high-viscosity zone is a single disc, and the single disc is detachably arranged in the polymerization kettle; a scraper group is also provided on the wall of the polymerization kettle between each two adjacent single discs in the high-viscosity zone, the scraper group includes multiple scrapers, and the distance between each scraper and the adjacent single disc is different.

2. The polymerizer for preparing a PETG or PCTG melt according to claim 1, wherein: The disc reactor in the high viscosity zone includes a ring and a plurality of spokes arranged inside the ring. The ring includes a first part and a second part. The first part is fixedly connected to the plurality of spokes respectively, and the second part is detachably connected to the first part.

3. The polymeric kettle for preparing PETG or PCTG melt according to claim 2, wherein: The detachable connection is a threaded connection; and / or the plurality of spokes is 5 spokes.

4. The polymeric kettle for preparing a PETG or PCTG melt according to claim 2, wherein: Positioning screw holes are designed to extend left and right from the spoke top of the disc reactor in the high viscosity area. The rings of adjacent spokes are designed with detachable segmented rings, which cooperate with the positioning screw holes at the spoke ends and are connected with impact bolts to form a smooth entire ring.

5. The polymeric kettle for preparing a PETG or PCTG melt according to claim 1, wherein: The multiple scrapers are all arranged vertically, with the ends of the scrapers pointing to the axis of the stirring shaft, and the projections of the multiple scrapers on the plane where the disc reactor is located are located on the same circle.

6. The polymerizer for preparing a PETG or PCTG melt according to claim 5, wherein: The length of each scraper is the same; and / or, between each two adjacent single-piece discs in the high-viscosity area, the distance between the scraper and the adjacent previous single-piece disc is distributed in an arithmetic progression; preferably, in each scraper group, the distance between the first scraper and the adjacent previous single-piece disc is 30 to 100 mm, and the distance between the last scraper and the adjacent next single-piece disc is 30 to 100 mm; and / or, in each scraper group, the axial distance between each two adjacent scrapers is 15 to 25 mm.

7. The polymerizer for preparing a PETG or PCTG melt according to claim 1, wherein: The cross section of the scraper is wedge-shaped; the thick end of the wedge faces the rotation direction of the disc reactor; and / or, five scrapers are arranged between every two adjacent single discs.

8. The polymerizer for preparing a PETG or PCTG melt according to claim 1, wherein: The total number of disc reactors in the low viscosity zone is 30 to 45, the total number of disc reactors in the medium and high viscosity zones and the high viscosity zone is 13 to 20, the total number of disc reactors in the high viscosity zone is 8 to 12, and the high viscosity zone is equipped with 8 to 12 scraper groups.

9. The polymerizer for preparing a PETG or PCTG melt according to claim 1, wherein: The length of the low viscosity zone is half of the length of the polymerization kettle, and the total length of the medium-high viscosity zone and the high viscosity zone is half of the length of the polymerization kettle; the length ratio of the medium-high viscosity zone to the high viscosity zone is 1:

2.

10. The polymerizer for preparing a PETG or PCTG melt according to claim 1, wherein: The polymerization kettle also includes a support base fixedly arranged on the inner wall of the main body for supporting two stirring shafts; and / or, the polymerization kettle also includes a prepolymer inlet located at the bottom of the front end of the low viscosity zone and a high viscosity melt outlet located at the bottom of the rear end of the high viscosity zone, and the high viscosity melt outlet is in a bell-mouth shape.

11. The polymerizer for preparing a PETG or PCTG melt according to claim 1, wherein: The diameter of the single disc in the high viscosity zone decreases from front to back, and the diameter of the last single disc in the high viscosity zone is 90% to 92% of the diameter of the first single disc; and / or, the distance between the disc reactor and the top of the polymerization kettle is 200 to 300 mm; and / or, the distance between the disc reactor and the bottom of the polymerization kettle is 20 to 50 mm.

12. A method for polymerizing PETG or PCTG, wherein the intrinsic viscosity of the PETG or PCTG is greater than 0.770, characterized in that: The polymerization method comprises the steps of sequentially subjecting terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol to an esterification reaction in a first esterification kettle and a second esterification kettle, and then to a prepolymerization reaction in a first prepolymerization kettle and a second prepolymerization kettle to obtain a prepolymer, and the step of subjecting the prepolymer to a polymerization reaction in a final polymerization kettle to obtain the PETG or PCTG. The final polymerization kettle is the polymerization kettle for preparing a PETG or PCTG melt according to any one of claims 1 to 10.

13. The polymerization method of PETG or PCTG according to claim 11, characterized in that: The intrinsic viscosity of the PETG is 0.770-0.820, and the intrinsic viscosity of the PCTG is 0.790-0.

820.

14. The polymerization method of PETG or PCTG according to claim 11, characterized in that: The preparation method further includes the step of adding an esterification catalyst to the first esterification kettle before the esterification reaction, wherein the esterification catalyst is selected from tetrabutyl titanate, tetraisopropyl titanate or tetra(2-ethylhexyloxy) titanate; preferably, the mass of the titanium element in the esterification catalyst accounts for 1 to 3 ppm of the mass of the PETG or PCTG.

15. The polymerization method of PETG or PCTG according to claim 11, characterized in that: The esterification reaction in the first esterification kettle is carried out at a pressure of 70 to 80 kPa; and / or, the esterification reaction in the first esterification kettle is carried out at 255 to 257° C.; and / or, the prepolymerization reaction in the first prepolymerization kettle is carried out at a vacuum degree of 9 to 12 kPa; and / or, the prepolymerization reaction in the first prepolymerization kettle is carried out at a vacuum degree of 9 to 12 kPa; and / or, the prepolymerization reaction in the first prepolymerization kettle is carried out at a vacuum degree of 9 to 12 kPa; and / or, the prepolymerization reaction in the first prepolymerization kettle is carried out at 258 to 266° C.; and / or, the prepolymerization reaction in the second prepolymerization kettle is carried out at a vacuum degree of 0.9 to 1.3 kPa; and / or, the prepolymerization reaction in the second prepolymerization kettle is carried out at 260 to 267° C.; and / or, the polymerization reaction in the final polymerization kettle is carried out at a vacuum degree of 100 to 130 Pa; and / or, the polymerization reaction in the final polymerization kettle is carried out at 265 to 275° C.

16. The polymerization method of PETG or PCTG according to claim 11, characterized in that: The esterification reaction in the second esterification kettle is carried out under normal pressure; and / or the second esterification kettle is a horizontal reactor and includes three compartments arranged in sequence from front to back, and the preparation method further includes the step of injecting a polymerization catalyst into the third compartment from the front to the rear of the second esterification kettle.

17. The polymerization method of PETG or PCTG according to claim 16, wherein: The polymerization catalyst is selected from a germanium dioxide aqueous solution, a suspension of germanium dioxide dispersed in a mixed solvent of water and ethylene glycol, a surface-deposited supported germanium-based catalyst, and a surface-deposited supported titanium-germanium-based composite catalyst; The surface-deposited supported germanium-based catalyst and the surface-deposited supported titanium-germanium-based composite catalyst comprise a carrier, a supported deposition layer, and an active component. The carrier is an inorganic porous material coated and modified by silicate. The supported deposition layer is located on the carrier and has a porous structure. The active component is deposited on the supported deposition layer. The surface-deposited supported germanium-based catalyst is prepared by a preparation method comprising the following steps: subjecting a suspension of a carrier, a water-soluble calcium salt, a water-soluble aluminum salt, a water-soluble zirconium salt, a water-soluble hydroxide, and an alkali to a precipitation reaction, filtering, and calcining to form the supported deposition layer on the carrier; the alkali is selected from carbonates and / or bicarbonates; the specific surface area of the carrier containing the supported deposition layer is greater than the specific surface area of the carrier; and dispersing the carrier containing the supported deposition layer in water to obtain a suspension of the carrier containing the supported deposition layer. The suspension of the carrier containing the supported deposition layer is subjected to a hydrolysis reaction with a germanium source to obtain a catalyst precursor; the catalyst precursor is subjected to a coating reaction with a silicate and water to load an active component on the supported deposition layer to obtain a surface-deposited supported germanium-based catalyst; The surface-deposited supported titanium-germanium-based catalyst is prepared by a preparation method comprising the following steps: subjecting a suspension of a support, a water-soluble calcium salt, a water-soluble aluminum salt, a water-soluble zirconium salt, a water-soluble hydroxide, and an alkali to a precipitation reaction, filtering, and calcining to form the supported deposition layer on the support; the alkali is selected from carbonates and / or bicarbonates; the specific surface area of the support containing the supported deposition layer is greater than the specific surface area of the support; and dispersing the support containing the supported deposition layer in water to obtain a suspension of the support containing the supported deposition layer; The suspension of the carrier containing the loaded deposition layer is subjected to a hydrolysis reaction with a hydrochloric acid solution of a germanium source and a titanium source to obtain a catalyst precursor; the catalyst precursor is subjected to a coating reaction with a silicate and water, and an active component is loaded on the loaded deposition layer to obtain a surface-deposited loaded titanium-germanium-based composite catalyst.

18. The polymerization method of PETG or PCTG according to claim 17, characterized in that: The polymerization catalyst is selected from a germanium dioxide aqueous solution or a suspension of germanium dioxide dispersed in a mixed solvent of water and ethylene glycol, and the mass of the germanium dioxide in the polymerization catalyst accounts for 100-150 ppm of the mass of PETG or PCTG; or, the polymerization catalyst is selected from a surface-deposited supported germanium-based catalyst, and the mass of the germanium element (calculated as germanium dioxide) in the polymerization catalyst accounts for 50-75 ppm of the mass of PETG or PCTG; or, the polymerization catalyst is selected from the surface-deposited supported titanium-germanium-based composite catalyst, and the masses of the titanium element and the germanium element (calculated as germanium dioxide) in the polymerization catalyst account for 8-12 ppm and 25-50 ppm of the mass of PETG or PCTG.

19. The polymerization method of PETG or PCTG according to claim 12, characterized in that: The polymerization method further includes the steps of pre-melting 1,4-cyclohexanedimethanol and conveying the melted 1,4-cyclohexanedimethanol to the first esterification kettle.

20. The polymerization method of PETG or PCTG according to claim 12, characterized in that: The polymerization kettle further includes steam feed ports for introducing superheated ethylene glycol steam, which are arranged at the top of the main body at the rear end of the low viscosity zone, the rear end of the medium and high viscosity zone, and the rear end of the high viscosity zone. The polymerization method further includes the step of using a metering system to meter the superheated ethylene glycol steam and introducing it into the final polymerization kettle.

21. The polymerization method of PETG or PCTG according to claim 12, wherein: When preparing PETG, the feeding molar ratio of the terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol is 1:0.92-0.93:0.325-0.315; or, when preparing PCTG, the feeding molar ratio of the terephthalic acid, ethylene glycol, and 1,4-cyclohexanedimethanol is 1:0.63-0.64:0.610-0.

615.

22. PETG or PCTG prepared by the polymerization method of PETG or PCTG according to any one of claims 12 to 21.

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