A mesogen-based method for alcoholysis regeneration of waste functionalized PET

Abstract

The application relates to a kind of waste functionalized PET alcoholysis regeneration methods based on oligomer, melt obtained by melting waste functionalized PET is transported to closed reactor, superheated dihydric alcohol steam is passed into closed reactor to make waste functionalized PET depolymerization to obtain oligomer, then functional monomer and dihydric alcohol are added in closed reactor and are co-esterified with oligomer, the product after co-esterification is sent to the polymerization stage of virgin polyester to carry out reaction, and functionalized regenerated polyester is prepared after reaction is finished;The degree of polymerization of oligomer is 3-30, and molecular weight distribution PDI is less than 3.The application can realize depolymerization in homogeneous state, avoid the process that solid phase PET gradually depolymerizes from surface layer to inner layer, can realize the degree of polymerization control of depolymerization product to prepare oligomer, and the uniformity increases after re-polymerization.

Description

[0001] The present application is a divisional application of the patent application "A Method for Regenerating Waste PET by Alcoholysis Based on Intermediates", the original application date of which is November 6, 2024, and the application number of which is 2024115698471. TECHNICAL FIELD

[0002] The present application belongs to the field of polymerization technology, and relates to a method for regenerating waste functionalized PET by alcoholysis based on intermediates. BACKGROUND

[0003] Polyethylene terephthalate (PET) is the most commonly used engineering plastic and fiber raw material, which has good chemical stability in the natural environment, but cannot be naturally degraded. The persistent accumulation of waste PET in the environment will cause microplastic and toxin pollution problems, so the recycling of PET has gradually become a research hotspot in recent years. Chemical recycling can depolymerize PET into terephthalic acid, ethylene glycol and other derived chemicals at the molecular level, which can realize "cyclic utilization" or "upgrading utilization" after separation and purification. Ethylene glycol, as one of the raw materials for polyester polymerization, can also be used as a nucleophilic agent to depolymerize polyester. After alcoholysis, no other chemical components are introduced, making it an ideal PET chemical depolymerization agent.

[0004] For example, patent CN113214458A discloses a method for preparing regenerated polyester by alcoholysis of waste polyester, which reports the use of oligomers and ethylene glycol to depolymerize PET to BHET and then polymerize it into regenerated polyester. Patent CN115141363A discloses a method for preparing regenerated cationic polyester from waste polyester, which depolymerizes PET to BHET copolymerization cationic regenerated polyester by using dihydric alcohol. Patent CN117999305A discloses a method for manufacturing regenerated polyester resin, which reports the use of one-step addition of polybasic acid and polyol for depolymerization and direct esterification, followed by polycondensation to prepare regenerated PET. By adding polybasic raw materials, direct regeneration after depolymerization is achieved.

[0005] Currently, PET alcoholysis recycling in the prior art is mainly through the depolymerization of PET in a dihydric alcohol solution. The depolymerization temperature is usually below the melting point of PET. Due to the different depolymerization efficiencies from the outside to the inside, in order to make the alcoholysis solution depolymerize uniformly, the final target of alcoholysis is mainly BHET and DMT, and the depolymerization is carried out in excess dihydric alcohol as a medium. If functionalized regenerated polyester is to be obtained, BHET or DMT is used as a raw material to polymerize with a functionalized monomer. Due to the limitations of complex components in the chemical method for functionalized PET, it is difficult to recycle functionalized PET. Because BHET or DMT obtained after depolymerization contains small molecules generated by the depolymerization of functional components, the purity of BHET or DMT is affected. Even if the purity of BHET or DMT is improved by purification, the process difficulty is increased, and the original functional components in the raw material are still wasted.

[0006] Therefore, it is of great significance to study a waste functionalized PET alcoholysis regeneration method based on mesopolymer to solve the problems of difficult control of polymer structure, wide molecular weight distribution, and limited large-scale popularization and application in the prior art. SUMMARY

[0007] The purpose of the present application is to solve the problems in the prior art and provide a waste functionalized PET alcoholysis regeneration method based on mesopolymer.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0009] A waste PET alcoholysis regeneration method based on mesopolymer, the melt obtained by melting the waste PET is transported to a closed reactor, superheated dihydric alcohol vapor is introduced into the closed reactor to depolymerize the waste PET to obtain mesopolymer, and then the mesopolymer is sent to the polymerization stage of virgin polyester for reaction, and the regenerated polyester is prepared after the reaction is completed.

[0010] The polymerization degree of the mesopolymer is 3-30, and the molecular weight distribution PDI is less than 3.

[0011] In the prior art, PET alcoholysis recovery is mainly through depolymerization of PET in dihydric alcohol solution, and the depolymerization temperature is usually below the melting point of PET. In order to make the alcoholysis solution depolymerize uniformly, the final target of alcoholysis is mainly BHET and DMT, and the depolymerization is carried out with excess dihydric alcohol as the medium. If the chemical recovery from PET to PET is carried out, the alcoholysis to BHET or DMT monomer is not the best recovery scheme, and the method from PET to mesopolymer and then to PET has the characteristics of short process, low energy consumption and high efficiency. The existing method of depolymerization with excess dihydric alcohol cannot realize the control of the polymerization degree of mesopolymer. The PET alcoholysis adopted in the present application is in the form of superheated dihydric alcohol vapor introduced into the polyester melt to realize alcoholysis. The superheated dihydric alcohol vapor is introduced into the closed reactor, the polyester melt is injected into the closed reactor, and the depolymerization is carried out at a certain temperature. The saturated vapor pressure can make the dihydric alcohol content in the melt consistent and uniformly distributed, so as to obtain mesopolymer with uniform molecular weight distribution, realize homogenization, and avoid the uneven phenomenon of depolymerization from the surface layer to the inner layer in the solid state.

[0012] As a preferred technical scheme:

[0013] The waste PET alcoholysis regeneration method based on the oligomer as described above, the waste PET is PET waste bottle pieces, polyester waste silk, polyester waste cloth or polyester-containing waste textiles; the melting temperature of the waste PET is 250-270 DEG C; the single-component waste PET such as PET waste bottle pieces, polyester waste silk, polyester waste cloth can be directly depolymerized and regenerated; the polyester-containing waste textiles include colored polyester textiles and polyester-cotton blended textiles, the colored polyester textiles need to be decolorized before being recycled to prepare the regenerated PET or to be blended with color master batches before spinning to prepare dark-colored regenerated PET, and the polyester-cotton blended textiles need to be filtered to remove the cotton components (three-stage filtration with filtration accuracy of 500 mesh, 200 mesh and 100 mesh) before being recycled and reused.

[0014] The waste PET alcoholysis regeneration method based on the oligomer as described above, the dihydric alcohol is ethylene glycol, 1,3-propanediol, 1,4-butanediol or 1,5-pentanediol.

[0015] The waste PET alcoholysis regeneration method based on the oligomer as described above, the temperature of the superheated dihydric alcohol vapor is 250-270 DEG C, the mass ratio of the superheated dihydric alcohol vapor to the melt is 2-10:1, and the depolymerization time is 10-30 min.

[0016] The waste PET alcoholysis regeneration method based on the oligomer as described above, the general structure of the oligomer is as follows:

[0017]

[0018] wherein x = 3-30, R is (CH2) z , and z = 2-5; by controlling the mass ratio of the superheated dihydric alcohol vapor to the melt and the depolymerization time, the value range of x can be controlled, so as to regulate the degree of polymerization of the oligomer.

[0019] The waste PET alcoholysis regeneration method based on the oligomer as described above, the specific process of the waste PET alcoholysis regeneration method based on the oligomer is as follows: the waste PET is conveyed to a closed reactor after being melted, then the superheated dihydric alcohol vapor is introduced into the closed container to depolymerize the waste PET to obtain the oligomer, and then the oligomer is sent to different polymerization stages of the virgin PET according to the degree of polymerization of the oligomer, so as to be polymerized to obtain the regenerated polyester; wherein the addition amount of the oligomer is 10-100 wt% of the regenerated polyester (when the addition amount is 100 wt%, there is no virgin PET);

[0020] By controlling the introduction flow and residence time of the superheated dihydric alcohol vapor, the PET can be controllably depolymerized into the oligomer with a certain degree of polymerization; according to different degrees of polymerization, the oligomer is conveyed to different polymerization stages of the virgin PET, so as to realize the regeneration of the polyester.

[0021] The method for regenerating waste PET by alcoholysis based on the intermediate polymer, the polymerization of the virgin PET comprises five polymerization stages, i.e., five-kettle polymerization, and the device used comprises a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle;

[0022] When x is 3-5, the intermediate polymer is sent to the first esterification kettle of the virgin PET;

[0023] When x is 6-12, the intermediate polymer is sent to the second esterification kettle of the virgin PET;

[0024] When x is 13-25, the intermediate polymer is sent to the first pre-polycondensation kettle of the virgin PET;

[0025] When x is 26-30, the intermediate polymer is sent to the second pre-polycondensation kettle of the virgin PET.

[0026] The method for regenerating waste PET by alcoholysis based on the intermediate polymer, the temperature of the first esterification kettle and the second esterification kettle is 240-260℃, and the pressure is 0-0.5MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 260-280℃, and the pressure is <200Pa.

[0027] The method for regenerating waste PET by alcoholysis based on the intermediate polymer, the polymerization degree of the regenerated PET obtained is 100-150, the intrinsic viscosity is 0.65-0.90dl / g, and the melting point is 250-260℃.

[0028] At present, the PET alcoholysis recovery in the prior art is mainly through the depolymerization of PET in a dihydric alcohol solution, and the depolymerization temperature is usually below the melting point of PET. In order to make the alcoholysis solution depolymerize uniformly, the final target of alcoholysis is mainly BHET and DMT, and the depolymerization is carried out by using excessive dihydric alcohol as a medium. If functional regenerated polyester is to be obtained, BHET or DMT is used as a raw material to carry out polymerization with a functional monomer. Since the chemical method of functional PET is limited by complex components, it is difficult to recycle the functional PET, because the BHET or DMT obtained after depolymerization will contain small molecules generated by the depolymerization of functional components, which affects the purity of BHET or DMT. Even if the purity of BHET or DMT is improved by purification, the process difficulty is also increased, and the original functional components are still wasted;

[0029] The PET alcoholysis adopted by the application is realized by passing superheated dihydric alcohol vapor into waste functionalized PET; the alcoholysis of the waste functionalized PET melt by directly passing the superheated dihydric alcohol vapor into a closed reactor can realize homogenization and avoid the uneven phenomenon of depolymerization from the surface layer to the inner layer in the solid state; at this time, the mesopolymer obtained by alcoholysis is a mesopolymer with functional components, and then functional monomers can be added according to the needs to control the proportion of the functional components (different functional monomers from the functional components in the raw materials can also be added), so as to obtain the functional regenerated polyester that the technical personnel want. Therefore, the method of the application not only effectively recycles the waste functionalized PET, shortens the process, but also fully utilizes the functional components therein.

[0030] A waste functionalized PET alcoholysis regeneration method based on mesopolymer, the melt obtained by melting the waste functionalized PET is transported to a closed reactor, superheated dihydric alcohol vapor is passed into the closed reactor to depolymerize the waste functionalized PET to obtain mesopolymer, then functional monomers and dihydric alcohol are added in the closed reactor to co-esterify with the mesopolymer, the product after co-esterification is sent to the polymerization stage of virgin polyester for reaction, and the functional regenerated polyester is prepared after the reaction is completed.

[0031] The polymerization degree of the mesopolymer is 3-30, and the molecular weight distribution PDI is less than 3.

[0032] As a preferred technical solution:

[0033] The waste functionalized PET is flame-retardant PET or cationic dyeable PET.

[0034] The dihydric alcohol is one or more of ethylene glycol, 1,3-propanediol, 1,4-butanediol and 1,5-pentanediol.

[0035] The functional monomer is sodium 5-sulfonate isophthalic acid, 3-hydroxyphenyl phosphonyl propionic acid, [(6-oxo-6H-dibenzo-(C,E)(1,2)-oxaphosphorin-6-keto)-methyl]-succinic acid or isophthalic acid.

[0036] The alcoholysis regeneration method of waste functionalized PET based on the intermediate polymer, the temperature of the superheated dihydric alcohol vapor is 250-270℃, the mass ratio of the superheated dihydric alcohol vapor to the melt is 2-10:1, the depolymerization time is 10-30min; the co-esterification temperature is 220-240℃, the co-esterification time is 2-4h, the co-esterification pressure is 0.2-0.5MPa, the addition amount of the functional monomer is 5-10wt% of the intermediate polymer, and the alcohol-acid ratio of the dihydric alcohol and the functional monomer added after the depolymerization of the intermediate polymer is 1.1-1.3:1.

[0037] The alcoholysis regeneration method of waste functionalized PET based on the intermediate polymer, the general structure of the intermediate polymer is:

[0038]

[0039] Wherein, x=3-30, by controlling the mass ratio of the superheated dihydric alcohol vapor to the melt and the depolymerization time, the value range of x can be controlled, so as to regulate the degree of polymerization of the intermediate polymer, R is (CH2) z , z=2-5, R0 is a functional component, the raw material corresponding to the functional component is a functional monomer, and the functional monomer corresponding to the functional component in the intermediate polymer can be the same substance as the functional monomer added after the depolymerization of the intermediate polymer, or not.

[0040] The alcoholysis regeneration method of waste functionalized PET based on the intermediate polymer, the specific process of the alcoholysis regeneration method of waste functionalized PET based on the intermediate polymer is: the waste functionalized PET is melted and then conveyed into a closed reactor, then the superheated dihydric alcohol vapor is introduced into the closed container to depolymerize the waste PET to obtain the intermediate polymer, then the functional monomer and dihydric alcohol are added into the closed reactor to co-esterify with the intermediate polymer, and then according to the degree of polymerization of the intermediate polymer, the co-esterification product is sent to different polymerization stages of the virgin PET to polymerize to obtain the regenerated functionalized polyester; wherein the addition amount of the intermediate polymer is 10-100wt% of the functionalized regenerated polyester, and when the addition amount is 100wt%, there is no virgin PET.

[0041] By controlling the flow rate and residence time of the superheated dihydric alcohol vapor, the PET is controllably depolymerized into the intermediate polymer with a certain degree of polymerization; according to different degrees of polymerization, the intermediate polymer is conveyed to the same polymerization stage of the virgin PET to realize polyester regeneration.

[0042] The alcoholysis regeneration method of waste functionalized PET based on the intermediate polymer, the polymerization of the virgin PET includes five polymerization stages, which is five-kettle polymerization, and the device used includes a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle.

[0043] When x is 3-5, the intermediate polymer is sent to the first esterification kettle of the virgin PET.

[0044] When x is 6-12, the intermediate polymer is sent to the second esterification kettle of virgin PET;

[0045] When x is 13-25, the intermediate polymer is sent to the first pre-polycondensation kettle of virgin PET;

[0046] When x is 26-30, the intermediate polymer is sent to the second pre-polycondensation kettle of virgin PET.

[0047] The method for regenerating waste functionalized PET by alcoholysis based on an intermediate polymer as described above, the temperature of the first esterification kettle and the second esterification kettle is 240-260℃, and the pressure is 0-0.5MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 260-280℃, and the pressure is <200Pa.

[0048] The method for regenerating waste functionalized PET by alcoholysis based on an intermediate polymer as described above, the polymerization degree of the regenerated PET prepared is 100-150, the intrinsic viscosity is 0.65-0.85dl / g, and the melting point is 230-250℃.

[0049] Advantages:

[0050] (1) The method for regenerating waste PET by alcoholysis based on an intermediate polymer, first melts the waste PET and then sends it to a reactor, and then passes overheated dihydric alcohol into the melt, so that depolymerization can be realized in a homogeneous state, avoiding the process of gradually depolymerizing from the surface to the inner layer of solid-phase PET, and the polymerization degree of the depolymerization product can be controlled to prepare an intermediate polymer, and the uniformity increases after re-polymerization.

[0051] (2) The method for regenerating waste PET by alcoholysis based on an intermediate polymer, dihydric alcohol is one of the raw materials for polyester synthesis, and the introduction of the molecular chain as a depolymerizing agent does not affect its re-polymerization, and the chemical structure of the alcoholysis product is mainly alcohol structure with hydroxyl groups, so that ester exchange can be directly performed to realize polycondensation reaction.

[0052] (3) The method for regenerating waste PET by alcoholysis based on an intermediate polymer, dihydric alcohol is not directly used as a medium, but is directly passed into the melt in the form of overheated steam, and the polymerization degree of the intermediate polymer is controlled by flow and time, and under the overheated condition, the excess dihydric alcohol steam overflowing from the melt can be directly collected at the upper end of the reactor and reused after recovery, thereby greatly reducing the cost.

[0053] (4) The method for regenerating waste PET by alcoholysis based on an intermediate polymer, intermediate polymers with different polymerization degrees can be added to the first esterification kettle, the second esterification kettle, the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle, and the process is connected with the preparation process of virgin polyester, so that partial addition or complete regeneration process can be realized, and the addition ratio of the regenerated polyester can be adjusted according to actual needs. BRIEF DESCRIPTION OF THE DRAWINGS

[0054] Figure 1 The schematic diagram of a method for alcoholysis regeneration of waste PET based on intermediate polymer;

[0055] Figure 2 The schematic diagram shows a method for alcoholysis regeneration of waste functionalized PET based on intermediate polymers; where y is the original degree of polymerization of the functionalized PET before depolymerization. DETAILED DESCRIPTION

[0056] Below in conjunction with specific embodiment, further set forth the present invention.Should be understood that these embodiments are only used to illustrate the present invention and are not used in limiting the scope of the present invention.In addition, should be understood that after reading the content taught by the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms fall equally within the scope limited by the appended claims of the application.

[0057] The test methods involved in the performance indicators of the present invention are as follows:

[0058] Degree of polymerization: Calculated by viscosity-average molecular weight; formula: [η] = KM α , x = M / 228; where K and α are solvent constants; the test solvent is phenol / tetrachloroethane with a mass ratio of 1:1; at 25 °C, K = 2.1 × 10 -4 , α=0.82), [η] is the test relative viscosity, M is the viscosity-average molecular weight of the polymer, and x is the degree of polymerization. Intrinsic viscosity: tested using an Ubbelohde viscometer with a capillary diameter of 0.7-0.8mm. Use an electronic balance to take 0.25g of the sample to be tested and dissolve it in a phenol-tetrachloroethane solvent with a mass ratio of 1:1. Use a 50ml volumetric flask to prepare a solution with a concentration of 0.005g / ml. Dissolve it completely in a 60-70℃ water bath, and then place the prepared solution in a 25℃ constant temperature water bath for ten minutes; the temperature of the constant temperature water bath is 25±0.1℃. Observe and record the solution flowing through the upper and lower scale lines of the Ubbelohde viscometer, take the average of three tests for each sample as the final result, and the calculation process is according to the following formula.

[0059]

[0060] Where: η r —relative viscosity; t1—solution flow time (s); t0—solvent flow time (s); η sp —Specific viscosity; [η]—Intrinsic viscosity.

[0061] Molecular weight distribution PDI: the number average molecular weight and molecular weight distribution (PDI) of the sample were tested by using a GPC-50 type gel permeation chromatograph of British PL company, the equipment was equipped with a differential refractive detector and a PL gel column (5 μm mixed-C), 1,1,1,3,3,3-hexafluoro-2-propanol was used as an eluent, and the flow rate was 1 mL / min; when testing, the sample was dried and dissolved in hexafluoroisopropanol to prepare a 1.0 mg / mL solution, and the test was carried out when the column temperature reached 40±1℃.

[0062] The raw material in the embodiment of the application is from a bulk chemical raw material.

[0063] Example 1

[0064] A waste PET alcoholysis regeneration method based on a mesopolymer, as shown in the figure, the specific steps are as follows: Figure 1

[0065] (1) Preparation of raw materials:

[0066] Waste PET: PET waste bottle pieces;

[0067] Diol: ethylene glycol;

[0068] (2) The melt obtained by melting the waste PET at a temperature of 250℃ is transported to a closed reactor, and then the superheated diol vapor at 250℃ is introduced into the closed container to depolymerize the waste PET for 30 min to obtain a mesopolymer with a polymerization degree of 3 and a molecular weight distribution PDI of 1.3;

[0069] The mass ratio of superheated diol vapor to melt is 10:1; the structural formula of the mesopolymer is:

[0070]

[0071] (3) According to the polymerization degree of the mesopolymer, the mesopolymer is sent to the first esterification kettle of virgin PET for polymerization reaction, the polymerization of virgin PET includes five polymerization stages, and the device used includes a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle, and the regenerated polyester is prepared after the reaction is completed;

[0072] The addition amount of the mesopolymer is 100wt% of the regenerated polyester; the temperature of the first esterification kettle and the second esterification kettle is 240℃, and the pressure is 0.5MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 260℃, and the pressure is 100Pa.

[0073] The polymerization degree of the finally prepared regenerated PET is 150, the intrinsic viscosity is 0.9 dl / g, and the melting point is 260℃.

[0074] Example 2 ​

[0075] A mesomer-based waste PET alcoholysis regeneration method, the specific steps are as follows:

[0076] (1) Preparation of raw materials:

[0077] Waste PET: polyester waste silk;

[0078] Diol: 1,3-propanediol;

[0079] (2) The melt obtained by melting the waste PET at a temperature of 255℃ is transported to a closed reactor, and then 255℃ superheated diol vapor is introduced into the closed container to depolymerize the waste PET for 25min to obtain a mesomer with a polymerization degree of 8 and a molecular weight distribution PDI of 1.7;

[0080] Wherein, the mass ratio of superheated diol vapor to melt is 6:1; the structural formula of the mesomer is:

[0081]

[0082] (3) According to the polymerization degree of the mesomer, the mesomer is sent to the second esterification kettle of virgin PET for polymerization reaction. The polymerization of virgin PET includes 5 polymerization stages, and the devices used include a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle. The reaction is completed to prepare a regenerated polyester;

[0083] Wherein, the addition amount of the mesomer is 75wt% of the regenerated polyester; the temperature of the first esterification kettle and the second esterification kettle is 245℃, and the pressure is 0.4MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 265℃, and the pressure is 100Pa.

[0084] The final prepared regenerated PET has a polymerization degree of 130, an intrinsic viscosity of 0.82dl / g, and a melting point of 257℃.

[0085] Example 3

[0086] A mesomer-based waste PET alcoholysis regeneration method, the specific steps are as follows:

[0087] (1) Preparation of raw materials:

[0088] Waste PET: polyester waste cloth;

[0089] Diol: 1,4-butanediol;

[0090] (2) The melt obtained by melting the waste PET at a temperature of 260℃ is transported to a closed reactor, and then 260℃ superheated diol vapor is introduced into the closed container to depolymerize the waste PET for 20min to obtain a mesomer with a polymerization degree of 21 and a molecular weight distribution PDI of 2.3;

[0091] wherein the mass ratio of the superheated diol vapor to the melt is 4:1; the structural formula of the intermediate polymer is:

[0092]

[0093] (3) According to the polymerization degree of the intermediate polymer, the intermediate polymer is sent to the first pre-polycondensation kettle of the virgin PET for polymerization reaction, the polymerization of the virgin PET includes five polymerization stages, the devices used include a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle, and a regenerated polyester is prepared at the end of the reaction;

[0094] wherein the addition amount of the intermediate polymer is 50wt% of the regenerated polyester; the temperature of the first esterification kettle and the second esterification kettle is 250℃, and the pressure is 0.2MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 270℃, and the pressure is 100Pa.

[0095] The polymerization degree of the finally prepared regenerated PET is 125, the intrinsic viscosity is 0.78dl / g, and the melting point is 255℃.

[0096] Example 4

[0097] A waste PET alcoholysis regeneration method based on an intermediate polymer, the specific steps are as follows:

[0098] (1) Preparation of raw materials:

[0099] Waste PET: colored polyester waste textiles;

[0100] Diol: 1,5-pentanediol;

[0101] (2) The melt obtained by melting the waste PET at a temperature of 265℃ is transported to a closed reactor, and then superheated diol vapor at 270℃ is introduced into the closed container to depolymerize the waste PET for 15min to obtain an intermediate polymer with a polymerization degree of 28 and a molecular weight distribution PDI of 2.7;

[0102] wherein the mass ratio of the superheated diol vapor to the melt is 2:1; the structural formula of the intermediate polymer is:

[0103]

[0104] (3) According to the polymerization degree of the intermediate polymer, the intermediate polymer is sent to the second pre-polycondensation kettle of the virgin PET for polymerization reaction, the polymerization of the virgin PET includes five polymerization stages, the devices used include a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle, and a regenerated polyester is prepared at the end of the reaction;

[0105] The addition amount of the intermediate polymer is 25wt% of the regenerated polyester; the temperature of the first esterification kettle and the second esterification kettle is 255℃, and the pressure is 0.1MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 275℃, and the pressure is 150Pa.

[0106] The polymerization degree of the finally prepared regenerated PET is 110, the intrinsic viscosity is 0.71dl / g, and the melting point is 253℃.

[0107] Example 5

[0108] An intermediate polymer-based waste PET alcoholysis regeneration method, the specific steps are as follows:

[0109] (1) Preparation of raw materials:

[0110] Waste PET: polyester-cotton blended waste textiles (the ratio of polyester / cotton is 80 / 20);

[0111] Diol: ethylene glycol;

[0112] (2) The melt obtained by melting the waste PET at a temperature of 270℃ is transported to a closed reactor, and the superheated diol vapor at 250℃ is introduced into the closed container to depolymerize the waste PET for 10min to obtain an intermediate polymer with a polymerization degree of 15 and a molecular weight distribution PDI of 2.0;

[0113] Wherein, the mass ratio of superheated diol vapor to melt is 8:1; the structural formula of the intermediate polymer is:

[0114]

[0115] (3) According to the polymerization degree of the intermediate polymer, the intermediate polymer is sent to the first pre-polycondensation kettle of the virgin PET for polymerization reaction, the polymerization of the virgin PET includes 5 polymerization stages, and the device used includes the first esterification kettle, the second esterification kettle, the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle, and the regenerated polyester is prepared after the reaction is completed;

[0116] Wherein, the addition amount of the intermediate polymer is 25wt% of the regenerated polyester; the temperature of the first esterification kettle and the second esterification kettle is 255℃, and the pressure is 0.1MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 275℃, and the pressure is 150Pa.

[0117] The polymerization degree of the finally prepared regenerated PET is 100, the intrinsic viscosity is 0.65dl / g, and the melting point is 250℃.

[0118] Example 6

[0119] An intermediate polymer-based waste functionalized PET alcoholysis regeneration method, as shown in Figure 2 The specific steps are as follows:

[0120] (1) Preparation of raw materials:

[0121] Waste functionalized PET: flame-retardant PET;

[0122] Diol: ethylene glycol;

[0123] Functional monomer: 3-hydroxyphenyl phosphonyl propionic acid;

[0124] (2) The melt obtained by melting the waste functionalized PET at 230°C is transported to a closed reactor, and superheated diol vapor at 250°C is introduced into the closed container to depolymerize the waste PET for 30 min to obtain a mesopolymer with a polymerization degree of 3 and a molecular weight distribution PDI of 1.6, and then the functional monomer and diol are added to the mesopolymer in the closed reactor, and the co-esterification of the mesopolymer is carried out at 220°C and 0.2 MPa for 4 h;

[0125] Wherein, the mass ratio of superheated diol vapor to melt is 10:1; the amount of functional monomer added is 8wt% of the mesopolymer, and the alcohol to acid ratio of diol and functional monomer added after depolymerization to obtain the mesopolymer is 1.15:1; the structural formula of the mesopolymer is:

[0126] R0 is a functional component, and the raw material corresponding to the functional component is a functional monomer;

[0127] (3) According to the polymerization degree of the mesopolymer, the product after co-esterification is sent to the first esterification kettle of virgin PET for polymerization reaction, and the polymerization of virgin PET includes five polymerization stages, and the devices used include a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle, and a functionalized regenerated polyester is prepared after the reaction is completed;

[0128] Wherein, the addition amount of the mesopolymer is 50wt% of the functionalized regenerated polyester; the temperature of the first esterification kettle and the second esterification kettle is 240°C, and the pressure is 0.5 MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 260°C, and the pressure is 100 Pa.

[0129] The polymerization degree of the finally prepared regenerated PET is 100, the intrinsic viscosity is 0.65 dl / g, and the melting point is 240°C.

[0130] Example 7

[0131] A waste functionalized PET alcoholysis regeneration method based on mesopolymer, the specific steps are as follows:

[0132] (1) Preparation of raw materials:

[0133] Waste functionalized PET: cationic dyeable PET;

[0134] Diol: 1,3-propanediol;

[0135] Functional monomer: sodium 5-sulfoisophthalate;

[0136] (2) The melt obtained by melting the waste functionalized PET at 240°C is transported into a closed reactor, and then superheated diol vapor at 255°C is introduced into the closed container to depolymerize the waste PET for 25 min to obtain a mesopolymer with a polymerization degree of 6 and a molecular weight distribution PDI of 1.9, and then the functional monomer and diol are added into the closed reactor, and the co-esterification of the mesopolymer, the functional monomer and the diol is carried out at 225°C and 0.3 MPa for 3.5 h;

[0137] wherein the mass ratio of superheated diol vapor to melt is 7:1; the addition amount of functional monomer is 10% of the mesopolymer, and the alcohol-acid ratio of diol to functional monomer added after obtaining the mesopolymer is 1.1:1; the structural formula of the mesopolymer is:

[0138] R0 is a functional component, and the raw material corresponding to the functional component is a functional monomer;

[0139] (3) According to the polymerization degree of the mesopolymer, the product after co-esterification is sent to the second esterification kettle of the virgin PET for polymerization reaction, and the polymerization of the virgin PET includes five polymerization stages, and the devices used include a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle, and a functionalized regenerated polyester is prepared after the reaction is completed;

[0140] wherein the addition amount of the mesopolymer is 70% of the functionalized regenerated polyester; the temperature of the first esterification kettle and the second esterification kettle is 245°C, and the pressure is 0.1 MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 265°C, and the pressure is 100 Pa.

[0141] The polymerization degree of the finally prepared regenerated PET is 120, the intrinsic viscosity is 0.7 dl / g, and the melting point is 245°C.

[0142] Example 8

[0143] A waste functionalized PET alcoholysis regeneration method based on a mesopolymer, and the specific steps are as follows:

[0144] (1) Preparation of raw materials:

[0145] Waste functionalized PET: flame-retardant PET;

[0146] Diol: 1,4-butanediol;

[0147] Functional monomer: [(6-oxo-6H-dibenzo-(C,E)(1,2)-oxaphosphorin-6-yl)-methyl]-succinic acid;

[0148] (2) The melt obtained by melting the waste functionalized PET at 220℃ is transported to a closed reactor, and then superheated dihydric alcohol vapor at 260℃ is introduced into the closed container to depolymerize the waste PET for 20 min to obtain a mesopolymer with a polymerization degree of 26 and a molecular weight distribution PDI of 2.9, and then functional monomers and dihydric alcohol are added to the mesopolymer in the closed reactor, and the co-esterification of the mesopolymer, dihydric alcohol and functional monomers is carried out at 230℃ and 0.35MPa for 3h;

[0149] The mass ratio of superheated dihydric alcohol vapor to melt is 2:1; the addition amount of functional monomers is 5wt% of the mesopolymer, and the alcohol to acid ratio of dihydric alcohol and functional monomers added after the mesopolymer is obtained is 1.3:1; the structural formula of the mesopolymer is:

[0150] R0 is a functional component, and the raw material corresponding to the functional component is a functional monomer;

[0151] (3) According to the polymerization degree of the mesopolymer, the product after co-esterification is sent to the second pre-polycondensation kettle of the virgin PET for polymerization reaction, and the polymerization of the virgin PET includes five polymerization stages, and the device used includes a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle, and the functionalized regenerated polyester is prepared after the reaction is completed;

[0152] The addition amount of the mesopolymer is 25wt% of the functionalized regenerated polyester; the temperature of the first esterification kettle and the second esterification kettle is 250℃, and the pressure is 0.4MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 270℃, and the pressure is 100Pa.

[0153] The polymerization degree of the finally prepared regenerated PET is 135, the intrinsic viscosity is 0.78dl / g, and the melting point is 235℃.

[0154] Example 9

[0155] A waste functionalized PET alcoholysis regeneration method based on a mesopolymer, and the specific steps are as follows:

[0156] (1) Preparation of raw materials:

[0157] Waste functionalized PET: cationic dyeable PET;

[0158] Dihydric alcohol: 1,5-pentanediol;

[0159] Functional monomer: isophthalic acid;

[0160] (2) the melt obtained by melting the waste functionalized PET at 230℃ is transported into a closed reactor, and then superheated dihydric alcohol vapor at 270℃ is introduced into the closed container to depolymerize the waste PET for 15 min to obtain a mesopolymer with a polymerization degree of 19 and a molecular weight distribution PDI of 2.4, and then the functional monomer and dihydric alcohol are added into the closed reactor, and the mesopolymer, the functional monomer and dihydric alcohol are subjected to co-esterification at 235℃ and 0.4 MPa for 2.5 h;

[0161] wherein the mass ratio of superheated dihydric alcohol vapor to melt is 6:1; the addition amount of functional monomer is 6wt% of the mesopolymer, and the alcohol-acid ratio of dihydric alcohol to functional monomer added after obtaining the mesopolymer is 1.25:1; the structural formula of the mesopolymer is:

[0162] R0 is a functional component, and the raw material corresponding to the functional component is a functional monomer;

[0163] (3) according to the polymerization degree of the mesopolymer, the product after co-esterification is transported to the first pre-polycondensation kettle of virgin PET for polymerization, the polymerization of virgin PET includes 5 polymerization stages, and the device used includes a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle, and the functionalized regenerated polyester is prepared after the reaction is completed;

[0164] wherein the addition amount of the mesopolymer is 10wt% of the functionalized regenerated polyester; the temperature of the first esterification kettle and the second esterification kettle is 255℃, and the pressure is 0.2 MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 275℃, and the pressure is 150 Pa.

[0165] The polymerization degree of the finally prepared regenerated PET is 145, the intrinsic viscosity is 0.83 dl / g, and the melting point is 250℃.

[0166] Example 10

[0167] A waste functionalized PET alcoholysis regeneration method based on a mesopolymer, and the specific steps are as follows:

[0168] (1) preparation of raw materials:

[0169] waste functionalized PET: flame-retardant PET;

[0170] dihydric alcohol: a mixed solution of 1,4-butanediol and 1,5-pentanediol with a volume ratio of 1:1;

[0171] functional monomer: 3-hydroxyphenyl phosphonyl propionic acid;

[0172] (2) the melt obtained by melting the waste functionalized PET at 225℃ is transported into a closed reactor, then superheated dihydric alcohol vapor at 260℃ is introduced into the closed container to depolymerize the waste PET for 25 min to obtain a mesopolymer with a polymerization degree of 15 and a molecular weight distribution PDI of 2.1, then functional monomers and dihydric alcohol are added into the closed reactor, and the mesopolymer, the functional monomers and the dihydric alcohol are subjected to co-esterification at 240℃ and 0.5 MPa for 2 h;

[0173] wherein the mass ratio of the superheated dihydric alcohol vapor to the melt is 4:1; the addition amount of the functional monomers is 8wt% of the mesopolymer, the alcohol-acid ratio of the dihydric alcohol and the functional monomers added after the mesopolymer is obtained is 1.2:1; and the structural formula of the mesopolymer is:

[0174] R0 is a functional component, and the raw material corresponding to the functional component is a functional monomer;

[0175] (3) according to the polymerization degree of the mesopolymer, the product after the co-esterification is transported into a first pre-polycondensation kettle of virgin PET for polymerization, the polymerization of the virgin PET includes five polymerization stages, and the device used includes a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle, and the functionalized regenerated polyester is prepared after the reaction is completed;

[0176] wherein the addition amount of the mesopolymer is 100wt% of the functionalized regenerated polyester; the temperature of the first esterification kettle and the second esterification kettle is 260℃, and the pressure is 0 MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 280℃, and the pressure is 150 Pa.

[0177] The polymerization degree of the finally prepared regenerated PET is 150, the intrinsic viscosity is 0.90 dl / g, and the melting point is 230℃.

Claims

1. A meso-mer based method for alcoholysis of waste functionalized PET for regeneration, characterized by: The melt obtained by melting the waste functionalized PET is transported to a closed reactor, superheated dihydric alcohol vapor is introduced into the closed reactor to depolymerize the waste functionalized PET to obtain a mesopolymer, then functional monomers and dihydric alcohol are added into the closed reactor to co-esterify the mesopolymer, and the co-esterified product is sent to the polymerization stage of virgin polyester to be polymerized to obtain the functionalized regenerated polyester. The general structure of the mesopolymer is: wherein x = 3 to 30, R is (CH2) z , z = 2 to 5, R0 is a functional component, and the raw material corresponding to the functional component is a functional monomer; The molecular weight distribution PDI of the mesopolymer is less than 3. The dihydric alcohol is one or more of ethylene glycol, 1,3-propanediol, 1,4-butanediol and 1,5-pentanediol. The functional monomer is sodium 5-sulfonate isophthalic acid, 3-hydroxyphenyl phosphonyl propionic acid, [(6-oxo-6H-dibenzo-(C,E)(1,2)-oxaphosphorinane-6-keto)-methyl]-succinic acid or isophthalic acid. The temperature of the superheated dihydric alcohol vapor is 250-270℃, the mass ratio of the superheated dihydric alcohol vapor to the melt is 2-10:1, the depolymerization time is 10-30min; the co-esterification temperature is 220-240℃, the co-esterification time is 2-4h, the co-esterification pressure is 0.2-0.5MPa, the amount of the functional monomer added is 5-10wt% of the mesopolymer, and the alcohol to acid ratio of the dihydric alcohol and the functional monomer added after the mesopolymer is obtained is 1.1-1.3:

1.

2. The meso-mer based method for alcoholysis of waste functionalized PET for recycling according to claim 1, wherein, The waste functionalized PET is flame-retardant PET or cationic dyeable PET; the melting temperature of the waste functionalized PET is 220-240℃.

3. The meso-mer based method for alcoholysis of waste functionalized PET for recycling according to claim 1, wherein, The specific process of the waste functionalized PET alcoholysis regeneration method based on the mesopolymer is as follows: the waste functionalized PET is melted and then transported to a closed reactor, superheated dihydric alcohol vapor is introduced into the closed reactor to depolymerize the waste PET to obtain a mesopolymer, then functional monomers and dihydric alcohol are added into the closed reactor to co-esterify the mesopolymer, and the co-esterified product is sent to different polymerization stages of virgin PET according to the polymerization degree of the mesopolymer to be polymerized to obtain a functionalized regenerated polyester; wherein the amount of the mesopolymer added is 10-100wt% of the functionalized regenerated polyester.

4. The meso-mer based method for alcoholysis regeneration of waste functionalized PET according to claim 3, characterized in that, The polymerization of the virgin PET includes five polymerization stages, i.e. five-kettle polymerization, and the devices used include a first esterification kettle, a second esterification kettle, a first pre-polycondensation kettle, a second pre-polycondensation kettle and a final polycondensation kettle. When x is 3-5, the mesopolymer is sent to the first esterification kettle of the virgin PET; When x is 6-12, the mesopolymer is sent to the second esterification kettle of the virgin PET; When x is 13-25, the mesopolymer is sent to the first pre-polycondensation kettle of the virgin PET; When x is 26-30, the mesopolymer is sent to the second pre-polycondensation kettle of the virgin PET.

5. The meso-mer based method for alcoholysis of waste functionalized PET for regeneration according to claim 4, wherein, The temperature of the first esterification kettle and the second esterification kettle is 240-260℃, and the pressure is 0-0.5MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 260-280℃, and the pressure is <200Pa.

6. The meso-mer based method for alcoholysis of waste functionalized PET for recycling according to any one of claims 1 to 5, characterized in that, The polymerization degree of the regenerated PET obtained is 100-150, the intrinsic viscosity is 0.65-0.85dl / g, and the melting point is 230-250℃.

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