Production method of colored polyethylene glycol terephthalate
Through the polycondensation reaction of bishydroxyethyl terephthalate, non-colored polyethylene terephthalate is synthesized in situ, solving the problems of high dyeing process costs and environmental pollution in the existing technology, and simplifying the production process and improving efficiency.
Patent Information
- Application Number
- CN202510575439.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-05-06
- Publication Date
- 2025-08-08
AI Technical Summary
In the prior art, when preparing colored PET, the dyeing process is expensive and pollutes the environment, and requires two steps of reaction generation and coloring.
Using polycondensation reaction of bishydroxyethyl terephthalate, colored polyethylene terephthalate is directly prepared by adding dyes in the pre-preparation stage and performing in-situ synthesis, simplifying the production process and combining synthesis and dyeing into one process.
Reduces production steps, saves time and costs, reduces the demand for water and other chemicals, reduces the emission of harmful volatile organic compounds, improves production efficiency and flexibility, and meets customized needs.
Smart Images
Figure CN120441820A_ABST
Abstract
Description
Technical Field
[0001] The present application relates to the technical field of polymer materials, and in particular to a method for producing colored polyethylene terephthalate. Background Art
[0002] Polyethylene terephthalate (PET) is a common plastic material used extensively in industry and daily life. PET is commonly used to make beverage bottles, food packaging, fibers, engineering plastics, carpet fibers, and more. PET is also commonly used as a 3D printing material and medical sutures.
[0003] Currently, the majority of colored PET produced domestically and internationally uses direct esterification and melt polycondensation of 1,4-dicarboxybenzene (PTA) and ethylene glycol (EG), or transesterification and melt polycondensation. The PET is then colored through molding, blending, or dyeing and impregnation. However, this method requires two steps: the reaction to form the PET and then coloring. The dyeing process also requires the use of large amounts of water and other chemicals, resulting in high costs and environmental pollution. Summary of the Invention
[0004] The purpose of the present application is to provide a method for producing colored polyethylene terephthalate, which adopts the condensation reaction of dihydroxyethyl terephthalate to prepare polyethylene terephthalate, and adds dye in the early stage of preparation to directly prepare colored polyethylene terephthalate through in situ synthesis, thereby solving the problems of high cost and environmental pollution caused by the dyeing process in the prior art and simplifying the production process.
[0005] In order to achieve one of the above-mentioned objectives of the invention, one embodiment of the present application provides a method for producing colored polyethylene terephthalate, comprising the following steps:
[0006] Pretreatment: A reaction system is constructed using terephthalic acid, a first catalyst, and ethylene glycol in which a first organic dye is dissolved. The reaction system is heated to 240-260° C. and stirred to produce bis(hydroxyethyl)terephthalate having a chromophoric group. The first organic dye has a group that reacts with the terminal hydroxyl group of the bis(hydroxyethyl)terephthalate.
[0007] Pre-polycondensation: add bis(hydroxyethyl) terephthalate, the second catalyst and the stabilizer to the above reaction system, continue stirring, heat and evacuate, maintain the temperature at 240-270°C, and evacuate until the pressure of the reaction system is less than 400 Pa;
[0008] Final polycondensation: After the gas pressure of the reaction system is less than 400 Pa, stir and heat to 270-300°C, react for 2-8 hours, and then terminate the reaction.
[0009] As a further improvement of one embodiment of the present application, the first organic dye contains at least one group selected from -COOH, -OH, -NH2, -Cl, -Br, -I, -POCl3, -PCl3, and -SH.
[0010] As a further improvement of one embodiment of the present application, the first catalyst is one or more of a metal salt catalyst, a protonic acid catalyst, a condensation agent catalyst, a metal organic catalyst, a nucleophilic substitution reaction catalyst, and a transition metal complex catalyst.
[0011] As a further improvement of one embodiment of the present application, the first catalyst is one or more of antimony ethylene glycol, 2,6-di-tert-butyl-p-cresol, tetrabutyl titanate, p-toluenesulfonic acid, N,N'-dicyclohexylcarbodiimide, cuprous halide, and cuprous iodide.
[0012] As a further improvement of one embodiment of the present application, the mass ratio of the first organic dye to terephthalic acid is (0-0.25):1, and the molar ratio of terephthalic acid to the first catalyst is 1:(0.01-0.0001).
[0013] As a further improvement of one embodiment of the present application, in the final polycondensation step, a first inorganic dye is added to the reaction system, and the first inorganic dye reacts with the terminal hydroxyl groups of polyethylene terephthalate.
[0014] As a further improvement of one embodiment of the present application, in the pretreatment step, a second organic dye and / or a second inorganic dye is also dispersed in the reaction system, and the second organic dye and / or the second inorganic dye are dispersed by ultrasound, wherein neither the second organic dye nor the second inorganic dye participates in the chemical reaction.
[0015] As a further improvement of one embodiment of the present application, in the pretreatment step, the gas pressure in the reaction system is controlled to be 1 to 5 bar; in the pre-polycondensation step, the reaction time is controlled to be 0.5 to 4 hours.
[0016] As a further improvement of one embodiment of the present application, the molar ratio of the second catalyst to bis(hydroxyethyl) terephthalate in the pre-polycondensation is (0.01-0.00001):1, and the molar ratio of the stabilizer to bis(hydroxyethyl) terephthalate is also (0.01-0.00001):1.
[0017] As a further improvement of one embodiment of the present application, the second catalyst in the pre-condensation includes an acidic catalyst, an alkaline catalyst, a metal catalyst, an enzyme catalyst, and an organic peroxide catalyst; the stabilizer includes an antioxidant, a light stabilizer, a heat stabilizer, and a chelating agent.
[0018] One or more technical solutions provided in this application have at least the following technical effects or advantages:
[0019] 1. Reduce production steps: In situ synthesis combines the synthesis and dyeing steps into one process, which simplifies the production process, saves time and cost, and improves production efficiency.
[0020] 2. Flexibility and customization: Using the in-situ synthesis method, the amount and ratio of dyes can be adjusted according to specific needs to obtain specific colors and meet the customized needs of different customers.
[0021] 3. Reduce costs and resource consumption: In situ synthesis reduces the demand for water and other chemicals, which is conducive to resource conservation.
[0022] 4. Prevent the release of volatile organic compounds (VOCs): Traditional dyeing processes may release harmful volatile organic compounds. Through in-situ synthesis, the emission of these harmful substances can be greatly reduced and green manufacturing can be promoted. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 This is a physical picture of the colored polyethylene terephthalate prepared in Example 1 of the present application.
[0024] Figure 2 This is the DSC chart of the colored polyethylene terephthalate prepared in Example 1 of the present application.
[0025] Figure 3 This is a physical picture of the colored polyethylene terephthalate prepared in Example 2 of the present application.
[0026] Figure 4 This is the DSC chart of the colored polyethylene terephthalate prepared in Example 2 of the present application.
[0027] Figure 5 This is a physical picture of the colored polyethylene terephthalate prepared in Example 3 of the present application.
[0028] Figure 6 This is the DSC chart of the colored polyethylene terephthalate prepared in Example 3 of the present application.
[0029] Figure 7 This is a physical picture of the colored polyethylene terephthalate prepared in Example 4 of the present application.
[0030] Figure 8 This is the DSC chart of the colored polyethylene terephthalate prepared in Example 4 of the present application. DETAILED DESCRIPTION
[0031] The present invention will be described in detail below with reference to specific embodiments, but these embodiments do not limit the present invention. Changes in reaction conditions, reactants, or raw material amounts made by ordinary technicians in this field according to these embodiments are all included in the scope of protection of the present invention.
[0032] The present invention provides a method for producing colored polyethylene terephthalate, comprising the following steps:
[0033] Pretreatment: A reaction system is constructed using terephthalic acid, a first catalyst, and ethylene glycol in which a first organic dye is dissolved. The reaction system is heated to 240-260° C. and stirred to produce bis(hydroxyethyl)terephthalate having a chromophoric group. The first organic dye has a group that reacts with the terminal hydroxyl group of the bis(hydroxyethyl)terephthalate.
[0034] Pre-polycondensation: add bis(hydroxyethyl) terephthalate, the second catalyst and the stabilizer to the above reaction system, continue stirring, heat and evacuate, maintain the temperature at 240-270°C, and evacuate until the pressure of the reaction system is less than 400 Pa;
[0035] Final polycondensation: After the gas pressure of the reaction system is less than 400 Pa, stir and heat to 270-300°C, react for 2-8 hours, and then terminate the reaction.
[0036] Because terephthalic acid is solid at room temperature and difficult to disperse the first organic dye, the first organic dye is dissolved in ethylene glycol, which is liquid at room temperature. At a temperature of 240-260°C, the terephthalic acid and ethylene glycol react in the presence of a first catalyst to form bis(hydroxyethyl)terephthalate. The first organic dye then chemically reacts with the hydroxyl groups of the bis(hydroxyethyl)terephthalate, imparting chromophoric groups to the bis(hydroxyethyl)terephthalate.
[0037] Preferably, the first organic dye has at least one group selected from -COOH, -OH, -NH2, -Cl, -Br, -I, -POCl3, -PCl3, and -SH, and these groups can react with the hydroxyl group of bis(hydroxyethyl) terephthalate.
[0038] After the first organic dye is pretreated, the reaction raw material bis(hydroxyethyl) terephthalate is added into the reaction system for polycondensation reaction, and the second catalyst and stabilizer required for the polycondensation reaction are added at the same time.
[0039] The bis(hydroxyethyl) terephthalate) undergoes polycondensation to form a polymer, which includes bis(hydroxyethyl) terephthalate with chromophoric groups after reaction with the first organic dye in the pretreatment step, and produces ethylene glycol as a byproduct. This results in the final polyethylene terephthalate with chromophoric groups, and the first organic dye is chemically bonded to the polyethylene terephthalate molecular chain, resulting in more stable coloration.
[0040] The unreacted terephthalic acid and ethylene glycol in the pretreatment step, the by-products in the pretreatment step, and the condensation by-product ethylene glycol are extracted by vacuum. When the pre-condensation step reaches the end, the gas pressure in the reaction vessel is stabilized below 400 Pa.
[0041] During the final polycondensation step, the polymers continue to react by heating to a higher temperature. As the molecular chains grow, the product viscosity increases. The degree of the final polycondensation reaction can be determined by the resistance of the stirring motor and the current drawn by the motor. When the resistance or current remains constant, the reaction is complete, ultimately forming polyethylene terephthalate.
[0042] During the production process, the stirring speed is controlled between 100 and 1000 rpm.
[0043] In some embodiments, the first catalyst is one or more of a metal salt catalyst, a protonic acid catalyst, a condensation agent catalyst, a metal organic catalyst, a nucleophilic substitution reaction catalyst, and a transition metal complex catalyst.
[0044] Preferably, the first catalyst is one or more of antimony ethylene glycol, 2,6-di-tert-butyl-p-cresol, tetrabutyl titanate, p-toluenesulfonic acid, N,N'-dicyclohexylcarbodiimide, cuprous halide, and cuprous iodide.
[0045] In some embodiments, the mass ratio of the first organic dye to terephthalic acid is (0-0.25):1, and the molar ratio of terephthalic acid to the first catalyst is 1:(0.01-0.0001).
[0046] The amount of the first organic dye added is related to the target color, but there is an upper limit. Otherwise, it may affect the degree of polymerization of the polyethylene terephthalate or the first organic dye may only physically adhere to the polymer surface, causing it to easily fade. If the first organic dye is not added, the product polyethylene terephthalate will retain its original color.
[0047] The amount of catalyst added is usually small, and the specific molar ratio varies depending on the relative molecular mass of the selected catalyst. The smaller the relative molecular mass of the first catalyst, the larger the molar ratio is selected, and the larger the relative molecular mass of the first catalyst, the smaller the molar ratio is selected.
[0048] In some embodiments, in the final polycondensation step, a first inorganic dye is added to the reaction system, and the first inorganic dye reacts with the terminal hydroxyl groups of polyethylene terephthalate.
[0049] In addition to adding organic dyes, inorganic dyes can also be added, such as the first inorganic dye that can react with the terminal hydroxyl groups of polyethylene terephthalate. The first inorganic dye can also participate in the chemical reaction, like the first organic dye, to make the dye color adhere more firmly.
[0050] Preferably, the first inorganic dye may be a metal complex inorganic dye, such as cobalt (II) phthalocyanine, MIL-101, titanium bismuth yellow, titanium nickel yellow, and cobalt green.
[0051] In some embodiments, in the pretreatment step, a second organic dye and / or a second inorganic dye is further dispersed in the reaction system, and the second organic dye and / or the second inorganic dye are dispersed by ultrasound, wherein neither the second organic dye nor the second inorganic dye participates in the chemical reaction.
[0052] In addition to the dye that participates in the chemical reaction, a dye that does not participate in the reaction can also be added in the pretreatment step. This can be the aforementioned second organic dye, the aforementioned second inorganic dye, or both. Ultrasonic dispersion is used to enhance the dispersion uniformity of the second organic dye and the second inorganic dye. The second organic dye and / or the second inorganic dye are added to the reaction system in the pretreatment step. Under stirring during the reaction process, the second organic dye and / or the second inorganic dye can be uniformly dispersed in the polymer product, polyethylene terephthalate. Compared to the current process of polymerizing first and then dyeing, this process does not require the use of large amounts of water or other organic solvents, and simplifies the production process.
[0053] Preferably, the second organic dye and the second inorganic dye are first dispersed and stirred using a high-speed dispersant, a planetary mixer or a homogenizer.
[0054] Preferably, the second organic dye may be an azo disperse dye, an anthraquinone dye, a heterocyclic dye, etc.; the second inorganic dye may be a metal oxide or a metal sulfide, etc.
[0055] More preferably, the second organic dye may be acid orange II, disperse orange, disperse yellow 23, fluorescent yellow 8GFF, etc.; the second inorganic dye may be titanium dioxide, cadmium sulfide, copper oxide, etc.
[0056] In some embodiments, in the pretreatment step, the gas pressure in the reaction vessel is controlled to be 1 to 5 bar; in the pre-polycondensation step, the reaction time is controlled to be 0.5 to 4 hours.
[0057] Because the esterification reaction of terephthalic acid and ethylene glycol is reversible, appropriately increasing the pressure can increase the frequency of collisions between the reactant molecules, favoring the reaction toward the formation of bis(hydroxyethyl) terephthalate, thereby improving the reaction rate and yield. Furthermore, a specific pressure can ensure that the reactants are in a suitable physical state, for example, preventing excessive volatilization at high temperatures, maintaining the stability of the reaction system, and controlling the state of the reactants.
[0058] Vacuuming is started based on the air pressure of 1 to 5 bar in the pretreatment step, and the air pressure in the reaction system is reduced to below 400 Pa within the reaction time of 0.5 to 4 hours in the pre-condensation step. That is, the vacuuming rate needs to be controlled in the pre-condensation step to ensure that the by-product ethylene glycol in the reaction system can be completely extracted.
[0059] In some embodiments, the molar ratio of the second catalyst to bis(hydroxyethyl) terephthalate in the pre-polycondensation is (0.01-0.00001):1, and the molar ratio of the stabilizer to bis(hydroxyethyl) terephthalate is also (0.01-0.00001):1. The amount of catalyst and stabilizer added is typically small, and the specific molar ratio varies depending on the relative molecular weight of the selected catalyst / stabilizer. A larger molar ratio is selected for a smaller relative molecular weight of the catalyst / stabilizer, while a smaller molar ratio is selected for a larger relative molecular weight of the catalyst / stabilizer.
[0060] Preferably, the second catalyst is one or a combination of acidic catalyst, alkaline catalyst, metal catalyst, enzyme catalyst, and organic peroxide catalyst.
[0061] More preferably, the second catalyst is selected from one or more of antimony trioxide, antimony glycol, 2,6-di-tert-butyl-p-cresol, titanium dioxide, tetrabutyl titanate, sodium hydroxide, and potassium hydroxide.
[0062] Preferably, the stabilizer is one or a combination of antioxidants, light stabilizers, heat stabilizers, and chelating agents.
[0063] More preferably, the stabilizer is selected from one or more of phenol, catechol, ethylenediaminetetraacetic acid, triethyl phosphate, triphenyl phosphite, pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], benzoic acid compounds, organophosphorus heat stabilizers, and metal salt heat stabilizers.
[0064] In some embodiments, during the pretreatment step, a protective gas is used to replace the air in the reaction system. Preferably, the protective gas can be nitrogen, an inert gas, or other gas that does not react with the substances in the reaction vessel.
[0065] In order to prevent oxygen in the air from affecting the substances in the reaction system, the air in the reaction vessel is replaced with a protective gas before heating.
[0066] The technical solution of the present application is further described below with reference to some specific embodiments.
[0067] Example 1
[0068] Pretreatment: Dissolve 11.28g of Disperse Blue 3GR, 12.92g of Reactive Black 5 and 9.45g of Reactive Violet KN-4R in 150g of ethylene glycol. Then add 150g of terephthalic acid, 0.53g of catalyst antimony glycol and ethylene glycol dissolved with the above-mentioned organic dyes into a 5L reactor. Then replace the air in the reactor with nitrogen three times, maintain the pressure in the reactor at 2 bar, and heat to 240°C.
[0069] Pre-polycondensation: 2700g of bis(hydroxyethyl) terephthalate, 0.72g of catalyst antimony ethylene glycol, and 0.116g of stabilizer triethyl phosphate were added to the reactor. The temperature was raised from 240°C to 270°C within 1.5 hours, and the pressure in the reactor was gradually adjusted to a vacuum state. Finally, it was stabilized at a high vacuum state of less than 400Pa, and the pre-polycondensation reaction was completed.
[0070] Final polycondensation: The reaction temperature is stabilized at 270°C and controlled under a high vacuum degree of less than 400 Pa. The final polycondensation reaction lasts for 4.5 hours to obtain colored recycled polyethylene terephthalate (rPET).
[0071] The obtained polymer had an intrinsic viscosity of 0.722 dL / g, a terminal carboxyl group of 8.2 mol / t, a diethylene glycol content of 1.21%, a melting point of 252.5° C., and color values L: 13.7, a: -0.2, and b: -1.7.
[0072] Example 2
[0073] Pretreatment: Dissolve 16g of Acid Yellow 36 in 80g of ethylene glycol. Add 120g of terephthalic acid, 0.22g of the catalyst 2,6-di-tert-butyl-p-cresol, and the ethylene glycol containing Acid Yellow 36 to a 5L reactor. Replace the air in the reactor with nitrogen three times while maintaining the pressure at 2 bar and heating to 240°C. Then, add 28g of nano-copper oxide, which has been dispersed sequentially using a planetary mixer and ultrasonic technology.
[0074] Pre-polycondensation: 2800g of bis(hydroxyethyl) terephthalate, 0.72g of catalyst 2,6-di-tert-butyl-p-cresol, and 0.116g of stabilizer triethyl phosphate were added to the reactor. The temperature was raised from 240°C to 270°C within 1.5 hours, and the pressure in the reactor was gradually adjusted to a vacuum state. Finally, it was stabilized at a high vacuum state of less than 200Pa, and the pre-polycondensation reaction was completed.
[0075] Final polycondensation: The reaction temperature is stabilized at 270°C and controlled under a high vacuum degree of less than 200 Pa. The final polycondensation reaction is continued for 4 hours to obtain colored recycled polyethylene terephthalate (rPET).
[0076] The obtained polymer had an intrinsic viscosity of 0.698 dL / g, a terminal carboxyl group of 6.9 mol / t, a diethylene glycol content of 1.61%, a melting point of 252.17° C., and color values L: 15.5, a: 9.6, and b: 2.4.
[0077] Example 3
[0078] Pretreatment: Dissolve 8.85g of azo blue and 9.5g of disperse blue 3GR in 75g of ethylene glycol. Then add 250g of terephthalic acid, 0.27g of catalyst antimony glycol, and ethylene glycol dissolved with the above-mentioned organic dye to a 5L reactor. Then replace the air in the reactor with nitrogen three times while maintaining the pressure in the reactor at 2 bar and raising the temperature to 240°C.
[0079] Pre-polycondensation: 2700g of bis(hydroxyethyl) terephthalate, 0.72g of catalyst antimony ethylene glycol, and 0.116g of stabilizer triethyl phosphate were added to the reactor. The temperature was raised from 240°C to 270°C within 1.5 hours, and the pressure in the reactor was gradually adjusted to a vacuum state. Finally, it was stabilized at a high vacuum state of less than 200Pa, and the pre-polycondensation reaction was completed.
[0080] Final polycondensation: The reactor was restored to normal pressure, and an ethylene glycol dispersion containing 6 g of cobalt phthalocyanine (II) was quickly added. The vacuum degree in the reactor was then increased and heated to a higher temperature. The reaction temperature was stabilized at 278°C and controlled at a high vacuum degree of less than 200 Pa. The final polycondensation reaction lasted for 4 hours to obtain colored recycled polyethylene terephthalate (rPET).
[0081] The obtained polymer had an intrinsic viscosity of 0.715 dL / g, a terminal carboxyl group of 4.2 mol / t, a diethylene glycol content of 1.27%, a melting point of 254.17° C., and color values L: 22.7, a: -16.6, and b: -35.1.
[0082] Example 4
[0083] Pretreatment: Dissolve 6.30g of Acid Mordant Black T and 5.50g of Disperse Blue 3GR in 75g of ethylene glycol. Add 250g of terephthalic acid, 0.27g of the catalyst antimony glycol, and the ethylene glycol containing the aforementioned organic dye to a 5L reactor. Displace the air in the reactor three times with nitrogen while maintaining the pressure at 2 bar and heating to 240°C. Then, add 16g of nano-titanium dioxide, dispersed sequentially using a planetary mixer and ultrasonic technology.
[0084] Pre-polycondensation: 2700g of bis(hydroxyethyl) terephthalate, 0.72g of catalyst antimony ethylene glycol, and 0.116g of stabilizer triethyl phosphate were added to the reactor. The temperature was raised from 240°C to 270°C within 1.5 hours, and the pressure in the reactor was gradually adjusted to a vacuum state. Finally, it was stabilized at a high vacuum state of less than 200Pa, and the pre-polycondensation reaction was completed.
[0085] Final polycondensation: The reactor was restored to normal pressure, and an ethylene glycol dispersion containing 6 g of MIL-101 was quickly added. The vacuum degree in the reactor was then increased and heated to a higher temperature. The reaction temperature was stabilized at 278°C and controlled at a high vacuum degree of less than 200 Pa. The final polycondensation reaction lasted for 4 hours to obtain colored recycled polyethylene terephthalate (rPET).
[0086] The obtained polymer had an intrinsic viscosity of 0.715 dL / g, a terminal carboxyl group content of 4.0 mol / t, a diethylene glycol content of 1.48%, a melting point of 256.50° C., and color values L: 34.7, a: 22.6, and b: -37.9.
[0087] It should be understood that although this specification is described in terms of implementation methods, not every implementation method contains only one independent technical solution. This narrative method of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each implementation method can also be appropriately combined to form other implementation methods that can be understood by those skilled in the art.
[0088] The series of detailed descriptions listed above are only specific descriptions of feasible implementation methods of this application. They are not intended to limit the scope of protection of this application. Any equivalent implementation methods or changes that do not deviate from the technical spirit of this application should be included in the scope of protection of this application.
Claims
1. A method for producing colored polyethylene terephthalate, characterized in that: The steps include: Pretreatment: A reaction system is constructed using terephthalic acid, a first catalyst, and ethylene glycol in which a first organic dye is dissolved. The reaction system is heated to 240-260° C. and stirred to produce bis(hydroxyethyl)terephthalate having a chromophoric group. The first organic dye has a group that reacts with the terminal hydroxyl group of the bis(hydroxyethyl)terephthalate. Pre-polycondensation: add bis(hydroxyethyl) terephthalate, the second catalyst and the stabilizer to the above reaction system, continue stirring, heat and evacuate, maintain the temperature at 240-270°C, and evacuate until the pressure of the reaction system is less than 400 Pa; Final polycondensation: After the gas pressure of the reaction system is less than 400 Pa, stir and heat to 270-300°C, react for 2-8 hours, and then terminate the reaction.
2. The method for producing colored polyethylene terephthalate according to claim 1, characterized in that: The first organic dye has at least one group selected from -COOH, -OH, -NH2, -Cl, -Br, -I, -POCl3, -PCl3, and -SH.
3. The method for producing colored polyethylene terephthalate according to claim 1, characterized in that: The first catalyst is one or more of a metal salt catalyst, a protonic acid catalyst, a condensation agent catalyst, a metal organic catalyst, a nucleophilic substitution reaction catalyst, and a transition metal complex catalyst.
4. The method for producing colored polyethylene terephthalate according to claim 3, characterized in that: The first catalyst is one or more of antimony ethylene glycol, 2,6-di-tert-butyl-p-cresol, tetrabutyl titanate, p-toluenesulfonic acid, N,N'-dicyclohexylcarbodiimide, cuprous halide, and cuprous iodide.
5. The method for producing colored polyethylene terephthalate according to claim 1, characterized in that: The mass ratio of the first organic dye to terephthalic acid is (0-0.25):1, and the molar ratio of terephthalic acid to the first catalyst is 1:(0.01-0.0001).
6. The method for producing colored polyethylene terephthalate according to claim 1, characterized in that: In the final polycondensation step, a first inorganic dye is added to the reaction system, and the first inorganic dye reacts with the terminal hydroxyl groups of polyethylene terephthalate.
7. The method for producing colored polyethylene terephthalate according to claim 1 or 6, characterized in that: In the pretreatment step, a second organic dye and / or a second inorganic dye is further dispersed in the reaction system. The second organic dye and / or the second inorganic dye are dispersed by ultrasound, wherein the second organic dye and the second inorganic dye do not participate in the chemical reaction.
8. The method for producing colored polyethylene terephthalate according to claim 1, characterized in that: In the pretreatment step, the gas pressure in the reaction system is controlled to be 1 to 5 bar; in the pre-polycondensation step, the reaction time is controlled to be 0.5 to 4 hours.
9. The method for producing colored polyethylene terephthalate according to claim 1, wherein: The molar ratio of the second catalyst to bis(hydroxyethyl) terephthalate in the pre-polycondensation is (0.01-0.00001):1, and the molar ratio of the stabilizer to bis(hydroxyethyl) terephthalate is also (0.01-0.00001):
1.
10. The method for producing colored polyethylene terephthalate according to claim 9, characterized in that: The second catalyst in the pre-condensation includes an acidic catalyst, an alkaline catalyst, a metal catalyst, an enzyme catalyst, and an organic peroxide catalyst; the stabilizer includes an antioxidant, a light stabilizer, a heat stabilizer, and a chelating agent.