A method for preparing in-situ polymerization regenerated functional polyester

Abstract

The present invention belongs to the technical field of polymer material preparation and recycling, and relates to a method for preparing in-situ polymerization regeneration functional polyester, wherein the melt obtained by melting waste PET is transported to a closed reactor, superheated diol steam is introduced into the closed reactor to depolymerize the waste PET to obtain a medium polymer, and then the functional powder is added to the closed reactor for in-situ mixing, and the mixed melt is transported to the synthesis stage of the original polyester for reaction, and the in-situ polymerization regeneration functional polyester is prepared after the reaction is completed; the degree of polymerization of the medium polymer is 4 to 30, and the molecular weight distribution PDI is less than 3. The present invention constructs an efficient PET alcoholysis functionalization reuse path, and the medium polymer melt with a certain molecular weight can better disperse the functional powder, and is combined with the original polyester polymerization route to realize partial or full in-situ polymerization functionalization regeneration.

Description

Technical Field

[0001] The invention belongs to the technical field of polymer material preparation and recovery, and relates to a method for preparing in-situ polymerization regeneration functional polyester. Background Art

[0002] Polyethylene terephthalate (PET) is the most commonly used engineering plastic and fiber raw material. In recent years, with the continuous improvement of people's living standards, the functional requirements for PET have gradually increased. Functionalized PET is mainly prepared by means of blending, in-situ polymerization and copolymerization. Blending and in-situ polymerization methods increase the functionality while ensuring the original physical and chemical properties of PET without changing the main chain structure of the PET molecule. However, when blending or in-situ polymerization, dispersion problems are usually faced, and many additives need to be introduced to disperse the powder. For PET in-situ polymerization, functional powders are usually dispersed in a slurry of PTA and ethylene glycol. Since PTA and functional powders are small molecular particles, they are easily agglomerated by electrostatic effects during the dispersion process, and further introduction of other dispersants for dispersion may affect the polymerization process.

[0003] For example, patent CN112458568B discloses a method for preparing a functionalized graphene intercalated in-situ polymerized polyester composite fiber, wherein graphite oxide is added to an N,N-dimethylformamide solvent to form a uniform dispersion, and then formed into a polymerization raw material with PTA and ethylene glycol. Patent CN111574698B discloses an organic microcapsule-encapsulated zinc borate in-situ polymerized flame-retardant and smoke-suppressing polyester and a preparation method thereof. After the zinc borate is treated with organic microencapsulation, in-situ polymerization addition can be achieved without affecting the polymerization reaction during polyester synthesis. Patent CN111269408B discloses a flame-retardant, anti-melting droplet anion health-care polyester based on in-situ polymerization and a preparation method thereof. The multifunctional polyester material is prepared by compounding the flame-retardant functional powder with Qibingshi in a PTA and EG slurry and dispersing them.

[0004] It can be seen from the above patents of in-situ polymerization of polyester that in-situ polymerization is currently carried out by dispersing PTA and EG at the initial stage of polymerization, mostly by adding dispersants, treating and compounding functional powders, etc. These methods not only increase the complexity of the production process, but also increase additional production costs and production instability.

[0005] Therefore, it is of great significance to study a method for preparing in-situ polymerization-regenerated functional polyester to solve the problem of uniform dispersion of functional powders in the polymerization system. Summary of the invention

[0006] The purpose of the present invention is to solve the problems existing in the prior art and provide a method for preparing in-situ polymerization regenerated functional polyester.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A method for preparing an in-situ polymerized regenerated functional polyester, comprising: conveying a melt obtained by melting waste PET through a twin-screw extruder to a closed reactor, introducing superheated diol steam into the closed reactor to depolymerize the waste PET to obtain a medium polymer, adding a functional powder into the closed reactor for in-situ mixing, conveying the mixed melt to a synthesis stage of virgin polyester for reaction (the synthesis process of virgin polyester is: PTA and EG are mixed into a slurry, and then subjected to esterification, pre-polycondensation, and final polycondensation reactions in sequence), and preparing the in-situ polymerized regenerated functional polyester after the reaction is completed;

[0009] The degree of polymerization of the mesopolymer is 3~30, and the molecular weight distribution PDI is <3.

[0010] In the prior art, in-situ polymerization of functional PET is mainly achieved by improving the dispersibility through functional powder modification, addition of dispersants and multi-component compounding in the preparation stage of PTA and EG slurry. Firstly, some components that affect the reaction of PET will be introduced, and secondly, it will cause production instability. The present invention introduces superheated diol vapor into a closed reactor, injects a polyester melt into the closed reactor, and performs depolymerization at a certain temperature. The saturated vapor pressure can make the diol content in the melt consistent and evenly distributed (at a certain temperature, the substance will form a saturated vapor pressure in the coexistence of gas and liquid, and the vapor pressure can be adjusted with the change of the external temperature, but does not change with the size of the container), thereby depolymerizing to obtain a mesopolymer with a uniform molecular weight distribution; the mesopolymer obtained by alcoholysis of waste polyester is used as a functional powder dispersion carrier. Compared with PTA and EG slurries, the mesopolymer with a certain molecular weight has better melt viscosity, can limit the thermal motion speed of functional molecules, reduce mutual contact, and avoid agglomeration caused by electrostatic effects. The polymerization degree (fluidity) of the mesopolymer generated during depolymerization can be regulated according to different functional components and addition amounts. After the corresponding dispersion is completed, it can be directly introduced into the original polyester preparation process without introducing other chemical structures. It has the characteristics of high dispersion, no addition, and easy matching, can simultaneously achieve the purpose of in-situ functionalization and recycled polyester, and can compound and add the functional powder according to actual needs.

[0011] As the preferred technical solution:

[0012] In the above-mentioned method for preparing the in-situ polymerization regenerated functional polyester, the melt is pumped into and out of the closed reactor by a melt pump.

[0013] In the method for preparing the functional polyester by in-situ polymerization, the waste PET is waste PET bottle flakes, polyester waste yarn, polyester waste cloth or waste textiles containing polyester; single-component waste PET such as waste PET bottle flakes, polyester waste yarn, polyester waste cloth can be directly depolymerized and regenerated; waste textiles containing polyester include colored polyester textiles and polyester-cotton blended textiles, and the colored polyester textiles need to be decolorized before recycling to prepare recycled PET or blended with masterbatch before spinning to complement the color to prepare dark recycled PET, and the polyester-cotton blended textiles need to filter out the cotton component before the polymer melt is conveyed (the cotton filtration is a three-stage filtration with filtration precisions of 500 mesh, 200 mesh and 100 mesh respectively) for recycling and reuse;

[0014] The melting temperature of waste PET is 250~270℃.

[0015] In the above-mentioned method for preparing the in-situ polymerization regenerated functional polyester, the diol is ethylene glycol, propylene glycol, butanediol or pentanediol.

[0016] In the above-mentioned method for preparing an in-situ polymerization regenerated functional polyester, the temperature of the superheated diol vapor is 250-270° C., the mass ratio of the superheated diol vapor to the melt is 2-10:1, and the depolymerization time is 10-30 min.

[0017] The above-mentioned method for preparing an in-situ polymerization regeneration functional polyester, the general structural formula of the intermediate polymer is , where R is (CH2) z , z=2~5, x=3~30.

[0018] As described above, the preparation method of in-situ polymerization regenerated functional polyester, the functional powder is one or more of carbon black, graphene, carbon nanotubes, jade powder, mica powder, tungsten oxide, ferrous oxide, zinc oxide and silver oxide, wherein carbon black, graphene and carbon nanotubes are carbon materials, jade powder and mica powder are cooling materials, tungsten oxide and ferrous oxide are heat storage and warmth preservation materials, zinc oxide and silver oxide are antibacterial materials, and the functional powder addition amount is 5~10wt% of the intermediate polymer.

[0019] According to the preparation method of in-situ polymerization regenerated functional polyester as described above, the synthesis of native polyester adopts a five-reactor polymerization process, and the mixed melt is conveyed to one or more of the first esterification kettle, the second esterification kettle, the first precondensation kettle and the second precondensation kettle. The polymerization degrees of the intermediate polymers in the melt conveyed to the first esterification kettle, the second esterification kettle, the first precondensation kettle and the second precondensation kettle are 3-5, 6-12, 12-25 and 25-30 respectively; the total addition amount of the intermediate polymer is 10-100wt% of the native polyester esterification liquid.

[0020] In the method for preparing in-situ polymerization regenerated functional polyester 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 precondensation kettle, the second precondensation kettle and the final polycondensation kettle is 260~280℃, and the pressure is <200Pa.

[0021] The method for preparing the in-situ polymerized regenerated functional polyester as described above has a polymerization degree of 100-150, an intrinsic viscosity of 0.65-0.90 dl / g, a melting point of 240-260°C, and the regenerated functional polyester can be applied to the fields of plastics and fibers.

[0022] Commonly used polyesters also include polytrimethylene terephthalate (PTT) and polybutylene terephthalate (PBT). The preparation of functional polyesters through functional masterbatches is the main means of preparing functional plastics and fibers. Because functional masterbatches have high content characteristics, all functional masterbatches usually require the matrix material to have sufficient fluidity to meet the needs of melt processing after functionalization. At present, high fluidity is achieved by branching or multi-polymerization to weaken the intermolecular forces, thereby increasing the fluidity of the melt. However, the direct addition of branched copolymerization modification will greatly change the rational properties of the polymer. At the same time, the dispersion of inorganic powders in the in-situ polymerization process is still carried out at the small molecule stage, and it is still difficult to achieve a dispersion effect if the melt viscosity is too low.

[0023] Furthermore, in order to solve the problem of uniform dispersion of functional powders in the polymerization system, developing a new fluidity adjustment strategy to optimize the performance of functional masterbatch is of great significance for promoting the functionalization process of polyester materials. Therefore, the present invention provides a method for preparing high-fluidity recycled polyester functional masterbatch, and the technical scheme adopted is as follows:

[0024] A method for preparing a high-fluidity recycled polyester functional masterbatch comprises the following steps: conveying a melt obtained by melting waste polyester to a closed reactor, introducing superheated mixed alcohol steam into the closed reactor to depolymerize the waste polyester to obtain a middle polymer, introducing the superheated mixed alcohol steam to achieve depolymerization in a homogeneous state, avoiding a solid-phase depolymerization process in which the depolymerization gradually depolymerizes from the surface layer to the inner layer, achieving control of the polymerization degree of the depolymerization product (middle polymer), and simultaneously achieving the introduction of a branched molecular chain structure, adding a functional powder into the closed reactor for in-situ mixing, conveying the mixed melt to a synthesis stage of virgin polyester for reaction, and preparing a high-fluidity recycled functional polyester masterbatch after the reaction is completed;

[0025] The mixed alcohol steam is a mixed steam of diols and polyols, the diols are ethylene glycol, propylene glycol or butanediol, and the polyols are glycerol or pentaerythritol;

[0026] The polymerization degree of the mesopolymer is 3~30, and the molecular weight distribution PDI is less than 3. The mesopolymer has a certain polymerization degree, which can limit the thermal movement speed of the functional powder, reduce the contact between each other, avoid agglomeration caused by electrostatic effect, and can match mesopolymers with different polymerization degrees according to the polarity and compound form of different functional powders to achieve the blending and addition of a high proportion of functional powders.

[0027] The existing high-fluidity polyester preparation technology is to add one or more branches at the synthetic raw material end (PTA / EG) stage or to improve the branch fluidity through reactive blending at the polyester chip processing stage. The method of improving fluidity of the present invention is to introduce mixed alcohol vapor into the waste polyester during depolymerization for depolymerization. After depolymerization, multiple functional groups are linked to the two ends of the intermediate polymer, and then mixed with the functional powder. First, when the intermediate polymer with a certain degree of polymerization is mixed with the functional powder, the melt viscosity will increase the adhesion ability with the functional powder, thereby avoiding agglomeration between the powders to achieve high dispersibility; secondly, after polycondensation, the branched end group structure will branch the macromolecular chain, thereby increasing the melt fluidity, and finally preparing a high-fluidity masterbatch. Since the source is waste polyester, the process can also achieve functional regeneration of polyester. Intermediates with different degrees of polymerization can be combined with the original polymerization process to achieve regeneration;

[0028] In the prior art, alcoholysis recovery of PET also involves depolymerizing waste PET using one or more diols and polyols as solvents; wherein PET is generally depolymerized in the solid phase, depolymerization occurs from the surface, the degree of polymerization of the alcoholysis solution is difficult to control, and the molecular weight distribution is wide; while in the present invention, superheated mixed alcohol vapor is introduced into a sealed container, so that every part of the polymer is superheated mixed alcohol vapor, and the depolymerization effect of every part of the polymer is the same, therefore, even if the present invention uses mixed alcohol vapor, the molecular weight distribution is still very narrow.

[0029] As the preferred technical solution:

[0030] In the method for preparing a high-fluidity recycled polyester functional masterbatch as described above, the proportion of polyols in the mixed alcohol vapor is 50-80wt%.

[0031] A method for preparing a high-fluidity recycled polyester functional masterbatch as described above, wherein the waste polyester is waste polyethylene terephthalate (PET), waste polypropylene terephthalate (PTT) or waste polybutylene terephthalate (PBT), and the waste polyester is in the form of bottle flakes, foam materials, friction materials or textiles;

[0032] The melting temperature of waste PET is 160~270℃.

[0033] In the method for preparing a high-fluidity recycled polyester functional masterbatch as described above, the temperature of the superheated mixed alcohol vapor is 250-270°C (blending of multiple different alcohols to form an azeotrope will lower the boiling point of the system), the mass ratio of the superheated mixed alcohol vapor to the melt is 2-7:1, and the depolymerization time is 10-30 min.

[0034] The method for preparing a high-fluidity recycled polyester functional masterbatch as described above, wherein the general structural formula of the intermediate polymer is and , where R is (CH2) z , z=2~4, x=3~30, R0 is a propylene glycol or pentaerythritol structure, and R1 is an ethylene glycol, propylene glycol or butanediol structure.

[0035] As described above, the preparation method of in-situ polymerization regenerated functional polyester, the functional powder is one or more of carbon black, graphene, carbon nanotubes, jade powder, mica powder, tungsten oxide, ferrous oxide, zinc oxide and silver oxide, wherein carbon black, graphene and carbon nanotubes are carbon materials, jade powder and mica powder are cooling materials, tungsten oxide and ferrous oxide are heat storage and warmth preservation materials, zinc oxide and silver oxide are antibacterial materials, and the functional powder addition amount is 30~40wt% of the intermediate polymer.

[0036] According to the method for preparing a high-fluidity recycled polyester functional masterbatch as described above, the synthesis of the original polyester adopts a five-reactor polymerization process, and the mixed melt is conveyed to one or more of the first esterification kettle, the second esterification kettle, the first precondensation kettle and the second precondensation kettle, and the melt is conveyed to the first esterification kettle, the second esterification kettle, the first precondensation kettle and the second precondensation kettle. The polymerization degrees of the intermediate polymers are 3-5, 6-12, 12-25 and 25-30 respectively; the total addition amount of the intermediate polymer is 30-100wt% of the original polyester esterification liquid.

[0037] In the method for preparing in-situ polymerization regenerated functional polyester 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 precondensation kettle, the second precondensation kettle and the final polycondensation kettle is 260~280℃, and the pressure is <200Pa.

[0038] The method for preparing a high-fluidity recycled polyester functional masterbatch as described above has a polymerization degree of 100-150, an intrinsic viscosity of 0.60-0.80 dl / g, and a melting point of 200-230°C.

[0039] Beneficial effects:

[0040] (1) The method for preparing the in-situ polymerization regenerated functional polyester of the present invention comprises firstly melting the waste PET and conveying it to a reactor, and then introducing the superheated diol into the melt, so as to realize depolymerization in a homogeneous state, avoid the process of solid phase depolymerization gradually depolymerizing from the surface layer to the inner layer, and realize the control of the polymerization degree of the depolymerization product (intermediate polymer);

[0041] (2) In the preparation method of the in-situ polymerization regeneration functional polyester of the present invention, diol as a depolymerizing agent does not affect the molecular chain structure, and the intermediate polymer has a certain degree of polymerization, which can limit the thermal movement speed of the functional powder, reduce the contact between each other, avoid agglomeration caused by electrostatic effect, and can match intermediate polymers with different degrees of polymerization according to the polarity and compound form of different functional powders;

[0042] (3) The method for preparing a functional polyester by in-situ polymerization regeneration of the present invention constructs an efficient PET alcoholysis functionalization and recycling path. After the functional powder is dispersed by the intermediate polymer, it can be directly added to the preparation process of the original polyester according to the polymerization degree of the intermediate polymer. It has the characteristics of high process matching and strong adaptability, and the addition ratio and regeneration ratio of the functional components can be flexibly adjusted during the polymerization stage. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 The schematic diagram is a method for preparing a functional polyester by in-situ polymerization regeneration;

[0044] Figure 2 This is a schematic diagram of a method for preparing a high-fluidity recycled polyester functional masterbatch. DETAILED DESCRIPTION

[0045] The present invention will be further described below in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it 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 within the scope limited by the appended claims of the application equally.

[0046] The test methods involved in the performance indicators in the embodiments and comparative examples of the present invention are as follows:

[0047] Degree of polymerization: Calculated by viscosity-average molecular weight; calculation 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 relative viscosity of the test, M is the viscosity-average molecular weight of the mesopolymer. When the mesopolymer relative viscosity is 0.0545, correspondingly, x=3.86, the mesopolymer degree of polymerization is 4; when the mesopolymer relative viscosity is 0.0996, correspondingly, x=8.04, the mesopolymer degree of polymerization is 8; when the mesopolymer relative viscosity is 0.2392, correspondingly, x=23.42, the mesopolymer degree of polymerization is 23. 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, and completely dissolve it in a 60~70℃ water bath, then put the prepared solution into a 25℃ constant temperature water bath for 10 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, and take the average of three tests for each sample as the final result. The calculation process is based on the following formula.

[0048] Formula (1);

[0049] Formula (2);

[0050] Formula (3);

[0051] Where: —Relative viscosity; —Solution flow time (s); —Solvent flow time (s); — specific viscosity; ]—Intrinsic viscosity.

[0052] Molecular weight distribution PDI: The number average molecular weight and molecular weight distribution (PDI) of the samples were tested using a GPC-50 gel permeation chromatograph produced by PL Company of the United Kingdom. The equipment was equipped with a differential refractometer and a PL gel column (5µm mixed-C), with 1,1,1,3,3,3-hexafluoro-2-propanol as the eluent and a flow rate of 1mL / min. During the test, the sample was dried and dissolved in hexafluoroisopropanol to prepare a 1.0mg / mL solution, and the test was carried out when the column temperature reached 40±1℃.

[0053] Example 1

[0054] A method for preparing in-situ polymerization regeneration functional polyester, such as Figure 1 As shown, the specific steps are as follows:

[0055] (1) Preparation of raw materials:

[0056] Waste PET: Waste PET bottle flakes;

[0057] Diol: ethylene glycol;

[0058] Functional powder: carbon black;

[0059] (2) Melting the waste PET at a temperature of 250° C., and pumping the melt obtained by melting into a closed reactor through a melt pump;

[0060] (3) Superheated diol steam at a temperature of 250°C is introduced into a closed reactor to depolymerize the waste PET for 30 minutes to obtain a polymer with a degree of polymerization of 3 and a molecular weight distribution (PDI) of 1.3, and then the functional powder is added to the closed reactor for in-situ mixing. The mixed melt is pumped out by a melt pump to the first esterification kettle of the original polyester for reaction. The synthesis of the original polyester adopts a five-kettle polymerization process. The temperature of the first esterification kettle and the second esterification kettle is 240°C and the pressure is 0.5MPa; the temperature of the first precondensation kettle, the second precondensation kettle and the final condensation kettle is 260°C and the pressure is 100Pa. After the reaction is completed, the in-situ polymerization regenerated functional polyester is prepared;

[0061] The mass ratio of superheated diol vapor to melt is 10:1; the amount of functional powder added is 10wt% of the intermediate polymer; the structural formula of the intermediate polymer is ; The amount of the polymer added is 10wt% of the original polyester esterification liquid.

[0062] The degree of polymerization of the finally obtained recycled functional polyester is 100, the intrinsic viscosity is 0.65 dl / g, and the melting point is 257°C.

[0063] Example 2

[0064] A method for preparing in-situ polymerization regeneration functional polyester, the specific steps are as follows:

[0065] (1) Preparation of raw materials:

[0066] Waste PET: Waste polyester yarn;

[0067] Diol: Propylene glycol;

[0068] Functional powder: jade powder;

[0069] (2) Melting the waste PET at a temperature of 255°C, and pumping the melt obtained by melting into a closed reactor through a melt pump;

[0070] (3) Superheated diol steam at a temperature of 255°C is introduced into a closed reactor to depolymerize the waste PET for 25 minutes to obtain a polymer with a degree of polymerization of 8 and a molecular weight distribution (PDI) of 1.6, and then the functional powder is added to the closed reactor for in-situ mixing. The mixed melt is pumped out by a melt pump to the second esterification kettle of the original polyester for reaction. The synthesis of the original polyester adopts a five-kettle polymerization process. The temperature of the first esterification kettle and the second esterification kettle is 245°C and the pressure is 0.5MPa; the temperature of the first precondensation kettle, the second precondensation kettle and the final condensation kettle is 265°C and the pressure is 100Pa. After the reaction is completed, the in-situ polymerization regenerated functional polyester is prepared;

[0071] The mass ratio of superheated diol vapor to melt is 6:1; the amount of functional powder added is 8wt% of the intermediate polymer; the structural formula of the intermediate polymer is ; The amount of polymer added is 30wt% of the original polyester esterification liquid.

[0072] The final obtained recycled functional polyester has a degree of polymerization of 115, an intrinsic viscosity of 0.75 dl / g and a melting point of 250°C.

[0073] Example 3

[0074] A method for preparing in-situ polymerization regeneration functional polyester, the specific steps are as follows:

[0075] (1) Preparation of raw materials:

[0076] Waste PET: Waste polyester fabric;

[0077] Diol: Butanediol;

[0078] Functional powder: tungsten oxide;

[0079] (2) Melting the waste PET at a temperature of 260°C, and pumping the melt obtained by melting into a closed reactor through a melt pump;

[0080] (3) Superheated diol steam at a temperature of 260°C is introduced into a closed reactor to depolymerize the waste PET for 20 minutes to obtain a polymer with a degree of polymerization of 21 and a molecular weight distribution PDI of 2.4, and then the functional powder is added to the closed reactor for in-situ mixing. The mixed melt is pumped out by a melt pump to the first pre-condensation kettle of the virgin polyester for reaction. The synthesis of the virgin polyester adopts a five-kettle polymerization process. The temperature of the first esterification kettle and the second esterification kettle is 250°C and the pressure is 0.3MPa; the temperature of the first pre-condensation kettle, the second pre-condensation kettle and the final condensation kettle is 270°C and the pressure is 100Pa. After the reaction is completed, the in-situ polymerization regenerated functional polyester is prepared;

[0081] The mass ratio of superheated diol vapor to melt is 4:1; the amount of functional powder added is 7wt% of the intermediate polymer; the structural formula of the intermediate polymer is ; The amount of polymer added is 50wt% of the original polyester esterification liquid.

[0082] The final obtained recycled functional polyester has a degree of polymerization of 125, an intrinsic viscosity of 0.8 dl / g, and a melting point of 245°C.

[0083] Example 4

[0084] A method for preparing in-situ polymerization regeneration functional polyester, the specific steps are as follows:

[0085] (1) Preparation of raw materials:

[0086] Waste PET: Colored polyester waste textiles;

[0087] Diol: Pentylene glycol;

[0088] Functional powder: zinc oxide;

[0089] (2) Melting the waste PET at a temperature of 265°C, and pumping the melt obtained by melting into a closed reactor through a melt pump;

[0090] (3) Superheated diol steam at a temperature of 270°C is introduced into a closed reactor to depolymerize the waste PET for 15 minutes to obtain a polymer with a degree of polymerization of 27 and a molecular weight distribution (PDI) of 2.7, and then the functional powder is added to the closed reactor for in-situ mixing. The mixed melt is pumped out by a melt pump to the second pre-condensation kettle of the original polyester for reaction. The synthesis of the original polyester adopts a five-kettle polymerization process. The temperature of the first esterification kettle and the second esterification kettle is 255°C and the pressure is 0.1MPa; the temperature of the first pre-condensation kettle, the second pre-condensation kettle and the final condensation kettle is 275°C and the pressure is 150Pa. After the reaction is completed, the in-situ polymerization regenerated functional polyester is prepared;

[0091] The mass ratio of superheated diol vapor to melt is 2:1; the amount of functional powder added is 6wt% of the intermediate polymer; the structural formula of the intermediate polymer is ; The amount of the polymer added is 100wt% of the original polyester esterification liquid.

[0092] The final obtained recycled functional polyester has a degree of polymerization of 140, an intrinsic viscosity of 0.85 dl / g and a melting point of 240°C.

[0093] Example 5

[0094] A method for preparing in-situ polymerization regeneration functional polyester, the specific steps are as follows:

[0095] (1) Preparation of raw materials:

[0096] Waste PET: polyester-cotton blended waste textiles (polyester / cotton ratio is 80 / 20);

[0097] Diol: ethylene glycol;

[0098] Functional powder: tungsten oxide and silver oxide in a mass ratio of 1:1;

[0099] (2) Melting the waste PET at a temperature of 270°C, and pumping the melt obtained by melting into a closed reactor through a melt pump;

[0100] (3) preparing mesopolymer a and mesopolymer b respectively;

[0101] (3.1) Superheated diol vapor at a temperature of 250°C was introduced into a closed reactor I to depolymerize the waste PET for 30 min to obtain a polymer a having a degree of polymerization of 4 and a molecular weight distribution (PDI) of 1.4;

[0102] (3.2) Superheated diol vapor at 250°C was introduced into the closed reactor II to depolymerize the waste PET for 15 min to obtain a polymer b having a degree of polymerization of 9 and a molecular weight distribution (PDI) of 1.6;

[0103] (4) adding a portion of the functional powder to the closed reactor I for in-situ mixing, the amount of the functional powder added being 5wt% of the intermediate polymer a, and the mixed melt being pumped out to the first esterification kettle of the original polyester by a melt pump for reaction; adding another portion of the functional powder to the closed reactor II for in-situ mixing, the amount of the functional powder added being 5wt% of the intermediate polymer b, and the mixed melt being pumped out to the second esterification kettle of the original polyester by a melt pump for reaction, and preparing the in-situ polymerized regenerated functional polyester after the reaction is completed; the synthesis of the original polyester adopts a five-reactor polymerization process, the temperature of the first esterification kettle and the second esterification kettle is 260°C, and the pressure is 0MPa; the temperature of the first pre-polycondensation kettle, the second pre-polycondensation kettle and the final polycondensation kettle is 280°C, and the pressure is 150Pa, and preparing the in-situ polymerized regenerated functional polyester after the reaction is completed;

[0104] The mass ratio of superheated diol vapor to melt is 9:1; the structural formulas of mesopolymer a and mesopolymer b are: ; The addition amounts of mesopolymer a and mesopolymer b are 25 wt% and 50 wt% of the original polyester esterification liquid, respectively.

[0105] The final obtained recycled functional polyester has a degree of polymerization of 150, an intrinsic viscosity of 0.9 dl / g and a melting point of 260°C.

[0106] Example 6

[0107] A method for preparing a high-fluidity recycled polyester functional masterbatch, such as Figure 2 As shown, the specific steps are as follows:

[0108] (1) Preparation of raw materials:

[0109] Waste polyester: waste polyethylene terephthalate bottle flakes;

[0110] Mixed alcohol steam: mixed steam of diol and polyol, diol is ethylene glycol, polyol is propylene glycol, and the volume ratio of diol to polyol is 1:5;

[0111] Functional powder: carbon black;

[0112] (2) Melting the waste polyester at a temperature of 250° C., and pumping the melt obtained by melting into a closed reactor through a melt pump;

[0113] (3) Superheated mixed alcohol steam at a temperature of 260°C is introduced into the closed reactor to depolymerize the waste polyester for 30 minutes to obtain a polymer with a degree of polymerization of 4 and a molecular weight distribution PDI of 1.6, and then the functional powder is added to the closed reactor for in-situ mixing. The mixed melt is transported to the first esterification kettle of the original polyester for reaction. The synthesis of the original polyester adopts a five-kettle polymerization process. The temperature of the first esterification kettle and the second esterification kettle is 240°C and the pressure is 0.5MPa; the temperature of the first precondensation kettle, the second precondensation kettle and the final condensation kettle is 260°C and the pressure is 150Pa. After the reaction is completed, a high-fluidity recycled polyester functional masterbatch is prepared;

[0114] The mass ratio of superheated mixed alcohol vapor to melt is 10:1; the amount of functional powder added is 10wt% of the intermediate polymer; the structural formula of the intermediate polymer is ; The amount of the polymer added is 100wt% of the original polyester esterification liquid.

[0115] The final obtained recycled functional polyester has a degree of polymerization of 150, an intrinsic viscosity of 0.8 dl / g and a melting point of 230°C.

[0116] Example 7

[0117] A method for preparing a high-fluidity recycled polyester functional masterbatch, the specific steps are as follows:

[0118] (1) Preparation of raw materials:

[0119] Waste polyester: waste polytrimethylene terephthalate foam;

[0120] Mixed alcohol steam: mixed steam of diol and polyol, the diol is propylene glycol, the polyol is pentaerythritol, and the volume ratio of diol to polyol is 1:3;

[0121] Functional powder: graphene;

[0122] (2) Melting the waste polyester at a temperature of 260° C., and pumping the melt obtained by melting into a closed reactor through a melt pump;

[0123] (3) Superheated mixed alcohol steam at a temperature of 250°C is introduced into the closed reactor to depolymerize the waste polyester for 25 minutes to obtain a polymer with a degree of polymerization of 9 and a molecular weight distribution PDI of 1.8, and then the functional powder is added to the closed reactor for in-situ mixing. The mixed melt is transported to the second esterification kettle of the original polyester for reaction. The synthesis of the original polyester adopts a five-kettle polymerization process. The temperature of the first esterification kettle and the second esterification kettle is 250°C and the pressure is 0.2MPa; the temperature of the first precondensation kettle, the second precondensation kettle and the final condensation kettle is 265°C and the pressure is 100Pa. After the reaction is completed, a high-fluidity recycled polyester functional masterbatch is prepared;

[0124] The mass ratio of superheated mixed alcohol vapor to melt is 8:1; the amount of functional powder added is 9wt% of the intermediate polymer; the structural formula of the intermediate polymer is ; The amount of polymer added is 60wt% of the original polyester esterification liquid.

[0125] The final obtained recycled functional polyester has a polymerization degree of 100, an intrinsic viscosity of 0.6 dl / g and a melting point of 200°C.

[0126] Example 8

[0127] A method for preparing a high-fluidity recycled polyester functional masterbatch, the specific steps are as follows:

[0128] (1) Preparation of raw materials:

[0129] Waste polyester: waste polybutylene terephthalate friction material;

[0130] Mixed alcohol steam: mixed steam of diol and polyol, the diol is butanediol, the polyol is propylene glycol, and the volume ratio of diol to polyol is 1:4.5;

[0131] Functional powder: carbon nanotubes;

[0132] (2) Melting the waste polyester at a temperature of 270°C, and pumping the melt obtained by melting into a closed reactor through a melt pump;

[0133] (3) Superheated mixed alcohol steam at a temperature of 260°C is introduced into the closed reactor to depolymerize the waste polyester for 20 minutes to obtain a polymer with a degree of polymerization of 17 and a molecular weight distribution PDI of 2.0, and then the functional powder is added to the closed reactor for in-situ mixing. The mixed melt is transported to the first precondensation kettle of the virgin polyester for reaction. The synthesis of the virgin polyester adopts a five-kettle polymerization process. The temperature of the first esterification kettle and the second esterification kettle is 260°C and the pressure is 0MPa; the temperature of the first precondensation kettle, the second precondensation kettle and the final condensation kettle is 270°C and the pressure is 150Pa. After the reaction is completed, a high-flowability recycled polyester functional masterbatch is prepared;

[0134] The mass ratio of superheated mixed alcohol vapor to melt is 6:1; the amount of functional powder added is 7wt% of the intermediate polymer; the structural formula of the intermediate polymer is ; The amount of polymer added is 40wt% of the original polyester esterification liquid.

[0135] The final obtained recycled functional polyester has a degree of polymerization of 135, an intrinsic viscosity of 0.76 dl / g, and a melting point of 225°C.

[0136] Example 9

[0137] A method for preparing a high-fluidity recycled polyester functional masterbatch, the specific steps are as follows:

[0138] (1) Preparation of raw materials:

[0139] Waste polyester: waste polyethylene terephthalate textiles;

[0140] Mixed alcohol steam: mixed steam of diol and polyol, the diol is ethylene glycol, the polyol is pentaerythritol, and the volume ratio of diol to polyol is 1:3.5;

[0141] Functional powder: jade powder;

[0142] (2) Melting the waste polyester at a temperature of 255°C, and pumping the melt obtained by melting into a closed reactor through a melt pump;

[0143] (3) Superheated mixed alcohol steam at a temperature of 270°C is introduced into a closed reactor to depolymerize the waste polyester for 20 minutes to obtain a polymer with a degree of polymerization of 26 and a molecular weight distribution PDI of 2.9, and then the functional powder is added to the closed reactor for in-situ mixing. The mixed melt is transported to the second precondensation kettle of the original polyester for reaction. The synthesis of the original polyester adopts a five-kettle polymerization process. The temperature of the first esterification kettle and the second esterification kettle is 245°C and the pressure is 0.4MPa; the temperature of the first precondensation kettle, the second precondensation kettle and the final condensation kettle is 275°C and the pressure is 100Pa. After the reaction is completed, a high-flowability recycled polyester functional masterbatch is prepared;

[0144] The mass ratio of superheated mixed alcohol vapor to melt is 2:1; the amount of functional powder added is 6wt% of the intermediate polymer; the structural formula of the intermediate polymer is ; The amount of the polymer added is 10wt% of the original polyester esterification liquid.

[0145] The degree of polymerization of the finally obtained recycled functional polyester is 130, the intrinsic viscosity is 0.71 dl / g, and the melting point is 205°C.

[0146] Example 10

[0147] A method for preparing a high-fluidity recycled polyester functional masterbatch, the specific steps are as follows:

[0148] (1) Preparation of raw materials:

[0149] Waste polyester: waste polytrimethylene terephthalate bottle flakes;

[0150] Mixed alcohol steam: mixed steam of diol and polyol, the diol is propylene glycol, the polyol is glycerol, and the volume ratio of diol to polyol is 1:5;

[0151] Functional powder: tungsten oxide and silver oxide in a mass ratio of 1:1;

[0152] (2) Melting the waste polyester at a temperature of 265°C, and pumping the melt obtained by melting into a closed reactor through a melt pump;

[0153] (3) preparing mesopolymer a and mesopolymer b respectively;

[0154] (3.1) Superheated mixed alcohol vapor at a temperature of 270° C. was introduced into the closed reactor I to depolymerize the waste polyester for 30 min to obtain a polymer a having a degree of polymerization of 4 and a molecular weight distribution (PDI) of 1.5;

[0155] (3.1) Superheated diol vapor at 260°C was introduced into the closed reactor II to depolymerize the waste PET for 25 min to obtain a polymer b having a degree of polymerization of 8 and a molecular weight distribution (PDI) of 1.8;

[0156] (4) A portion of the functional powder is added to the closed reactor I for in-situ mixing, the amount of the functional powder added is 5wt% of the intermediate polymer a, and the mixed melt is transported to the first esterification kettle of the original polyester for reaction; another portion of the functional powder is added to the closed reactor II for in-situ mixing, the amount of the functional powder added is 5wt% of the intermediate polymer b, and the mixed melt is transported to the second esterification kettle of the original polyester for reaction. The synthesis of the original polyester adopts a five-kettle polymerization process, the temperature of the first esterification kettle and the second esterification kettle is 255°C, and the pressure is 0.1MPa; the temperature of the first pre-condensation kettle, the second pre-condensation kettle and the final condensation kettle is 280°C, the pressure is 100Pa, and the reaction is completed to prepare a high-fluidity recycled polyester functional masterbatch;

[0157] The mass ratio of superheated mixed alcohol vapor to melt is 6:1; the structural formulas of mesopolymer a and mesopolymer b are: ; The addition amounts of mesopolymer a and mesopolymer b are 10wt% and 15wt% of the original polyester esterification liquid respectively.

[0158] The final obtained recycled functional polyester has a degree of polymerization of 115, an intrinsic viscosity of 0.64 dl / g, and a melting point of 220°C.

Claims

1. A method for preparing in-situ polymerization regeneration functional polyester, characterized in that: The melt obtained by melting waste PET is transported to a closed reactor, superheated diol steam is introduced into the closed reactor to depolymerize the waste PET to obtain a polymer, and then the functional powder is added to the closed reactor for in-situ mixing. The mixed melt is transported to the synthesis stage of the original polyester for reaction, and the in-situ polymerization regenerated functional polyester is prepared after the reaction is completed; The degree of polymerization of the mesopolymer is 3 to 30, and the molecular weight distribution PDI is less than 3; The temperature of the superheated glycol vapor is 250-270°C, the mass ratio of the superheated glycol vapor to the melt is 2-10:1, and the depolymerization time is 10-30 minutes; The functional powder is one or more of carbon black, graphene, carbon nanotubes, jade powder, mica powder, tungsten oxide, ferrous oxide, zinc oxide and silver oxide, and the added amount of the functional powder is 5-10wt% of the intermediate polymer.

2. The method for preparing an in-situ polymerization regenerated functional polyester according to claim 1, characterized in that: The melt is pumped into and out of the closed reactor by a melt pump.

3. The method for preparing an in-situ polymerization regenerated functional polyester according to claim 1, characterized in that: Waste PET refers to waste PET bottle flakes, waste polyester yarn, waste polyester cloth or waste textiles containing polyester; The melting temperature of waste PET is 250-270℃.

4. The method for preparing an in-situ polymerization regenerated functional polyester according to claim 1, characterized in that: The diol is ethylene glycol, propylene glycol, butylene glycol or pentylene glycol.

5. The method for preparing an in-situ polymerization regenerated functional polyester according to claim 1, characterized in that: The general structural formula of the mesopolymer is Where R is (CH2) z , z=2~4, x=3~30.

6. The method for preparing an in-situ polymerization regenerated functional polyester according to claim 1, characterized in that: The synthesis of the original polyester adopts a five-pot polymerization process, and the mixed melt is transported to one or more of the first esterification kettle, the second esterification kettle, the first precondensation kettle and the second precondensation kettle; the polymerization degrees of the intermediate polymers in the melts transported to the first esterification kettle, the second esterification kettle, the first precondensation kettle and the second precondensation kettle are 3-5, 6-12, 12-25 and 25-30 respectively; the total addition amount of the intermediate polymer is 10-100wt% of the original polyester esterification liquid.

7. The method for preparing an in-situ polymerization regenerated functional polyester according to claim 1, characterized in that: The temperature of the first esterification kettle and the second esterification kettle is 240-260°C, 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°C, and the pressure is <200Pa.

8. The method for preparing an in-situ polymerization regenerated functional polyester according to claim 1, characterized in that: The polymerization degree of the recycled functional polyester is 100-150, the intrinsic viscosity is 0.65-0.90 dl / g, and the melting point is 240-260°C.

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