CN115232298A - Method for preparing regenerated cationic dyeable polyester chip from waste polyester material and product - Google Patents
Method for preparing regenerated cationic dyeable polyester chip from waste polyester material and product Download PDFInfo
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- CN115232298A CN115232298A CN202110435088.XA CN202110435088A CN115232298A CN 115232298 A CN115232298 A CN 115232298A CN 202110435088 A CN202110435088 A CN 202110435088A CN 115232298 A CN115232298 A CN 115232298A
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- 229920000728 polyester Polymers 0.000 title claims abstract description 109
- 239000002699 waste material Substances 0.000 title claims abstract description 49
- 238000000034 method Methods 0.000 title claims abstract description 47
- 239000000463 material Substances 0.000 title claims abstract description 41
- 125000002091 cationic group Chemical group 0.000 title claims abstract description 26
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims abstract description 311
- 238000006068 polycondensation reaction Methods 0.000 claims abstract description 60
- 238000001035 drying Methods 0.000 claims abstract description 28
- 238000007334 copolymerization reaction Methods 0.000 claims abstract description 27
- 238000002844 melting Methods 0.000 claims abstract description 26
- 230000008018 melting Effects 0.000 claims abstract description 26
- 239000012535 impurity Substances 0.000 claims abstract description 24
- 239000007788 liquid Substances 0.000 claims abstract description 17
- LLLVZDVNHNWSDS-UHFFFAOYSA-N 4-methylidene-3,5-dioxabicyclo[5.2.2]undeca-1(9),7,10-triene-2,6-dione Chemical compound C1(C2=CC=C(C(=O)OC(=C)O1)C=C2)=O LLLVZDVNHNWSDS-UHFFFAOYSA-N 0.000 claims abstract description 16
- 238000010438 heat treatment Methods 0.000 claims abstract description 16
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 15
- 239000002994 raw material Substances 0.000 claims abstract description 13
- 238000001704 evaporation Methods 0.000 claims abstract description 10
- 238000012691 depolymerization reaction Methods 0.000 claims abstract description 9
- 150000001768 cations Chemical class 0.000 claims abstract description 6
- 238000006243 chemical reaction Methods 0.000 claims description 26
- 239000000155 melt Substances 0.000 claims description 20
- 230000035484 reaction time Effects 0.000 claims description 20
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims description 16
- 230000009467 reduction Effects 0.000 claims description 14
- 238000001816 cooling Methods 0.000 claims description 11
- 238000002425 crystallisation Methods 0.000 claims description 11
- 230000008025 crystallization Effects 0.000 claims description 11
- 238000004821 distillation Methods 0.000 claims description 11
- 238000004064 recycling Methods 0.000 claims description 10
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 9
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 7
- 230000008020 evaporation Effects 0.000 claims description 6
- 238000011084 recovery Methods 0.000 claims description 6
- 238000004519 manufacturing process Methods 0.000 claims description 5
- 230000008569 process Effects 0.000 abstract description 15
- 238000005265 energy consumption Methods 0.000 abstract description 4
- 239000000178 monomer Substances 0.000 description 37
- 239000000243 solution Substances 0.000 description 23
- 238000001914 filtration Methods 0.000 description 12
- 239000000047 product Substances 0.000 description 12
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 description 6
- 239000000835 fiber Substances 0.000 description 5
- 238000000265 homogenisation Methods 0.000 description 5
- 239000011259 mixed solution Substances 0.000 description 5
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 4
- 238000009833 condensation Methods 0.000 description 4
- 230000005494 condensation Effects 0.000 description 4
- WOZVHXUHUFLZGK-UHFFFAOYSA-N dimethyl terephthalate Chemical compound COC(=O)C1=CC=C(C(=O)OC)C=C1 WOZVHXUHUFLZGK-UHFFFAOYSA-N 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 239000004753 textile Substances 0.000 description 4
- 230000000052 comparative effect Effects 0.000 description 3
- 238000000053 physical method Methods 0.000 description 3
- 150000003384 small molecules Chemical class 0.000 description 3
- QPFMBZIOSGYJDE-UHFFFAOYSA-N 1,1,2,2-tetrachloroethane Chemical compound ClC(Cl)C(Cl)Cl QPFMBZIOSGYJDE-UHFFFAOYSA-N 0.000 description 2
- RNFJDJUURJAICM-UHFFFAOYSA-N 2,2,4,4,6,6-hexaphenoxy-1,3,5-triaza-2$l^{5},4$l^{5},6$l^{5}-triphosphacyclohexa-1,3,5-triene Chemical compound N=1P(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP(OC=2C=CC=CC=2)(OC=2C=CC=CC=2)=NP=1(OC=1C=CC=CC=1)OC1=CC=CC=C1 RNFJDJUURJAICM-UHFFFAOYSA-N 0.000 description 2
- 239000002202 Polyethylene glycol Substances 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 235000013361 beverage Nutrition 0.000 description 2
- 239000006227 byproduct Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000003063 flame retardant Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000003973 paint Substances 0.000 description 2
- 229920001223 polyethylene glycol Polymers 0.000 description 2
- 238000007781 pre-processing Methods 0.000 description 2
- 238000007086 side reaction Methods 0.000 description 2
- 238000009987 spinning Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- SNWXBKXYECKHMT-UHFFFAOYSA-L C(C1=CC(C(=O)[O-])=CC=C1)(=O)[O-].C(CO)O.[Na+].[Na+] Chemical compound C(C1=CC(C(=O)[O-])=CC=C1)(=O)[O-].C(CO)O.[Na+].[Na+] SNWXBKXYECKHMT-UHFFFAOYSA-L 0.000 description 1
- 229920000742 Cotton Polymers 0.000 description 1
- ISWSIDIOOBJBQZ-UHFFFAOYSA-N Phenol Chemical compound OC1=CC=CC=C1 ISWSIDIOOBJBQZ-UHFFFAOYSA-N 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- -1 after pretreatment Substances 0.000 description 1
- 238000006136 alcoholysis reaction Methods 0.000 description 1
- 230000015556 catabolic process Effects 0.000 description 1
- 238000001311 chemical methods and process Methods 0.000 description 1
- 238000012824 chemical production Methods 0.000 description 1
- 238000000354 decomposition reaction Methods 0.000 description 1
- 238000006731 degradation reaction Methods 0.000 description 1
- 125000000118 dimethyl group Chemical group [H]C([H])([H])* 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005469 granulation Methods 0.000 description 1
- 230000003179 granulation Effects 0.000 description 1
- 238000009776 industrial production Methods 0.000 description 1
- 238000002074 melt spinning Methods 0.000 description 1
- 239000012785 packaging film Substances 0.000 description 1
- 229920006280 packaging film Polymers 0.000 description 1
- 238000005453 pelletization Methods 0.000 description 1
- 229920000642 polymer Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 238000000746 purification Methods 0.000 description 1
- 238000002791 soaking Methods 0.000 description 1
- 229910052708 sodium Inorganic materials 0.000 description 1
- 239000011734 sodium Substances 0.000 description 1
- BDHFUVZGWQCTTF-UHFFFAOYSA-M sulfonate Chemical compound [O-]S(=O)=O BDHFUVZGWQCTTF-UHFFFAOYSA-M 0.000 description 1
- 238000010998 test method Methods 0.000 description 1
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- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
- C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
- C08G63/68—Polyesters containing atoms other than carbon, hydrogen and oxygen
- C08G63/688—Polyesters containing atoms other than carbon, hydrogen and oxygen containing sulfur
- C08G63/6884—Polyesters containing atoms other than carbon, hydrogen and oxygen containing sulfur derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/6886—Dicarboxylic acids and dihydroxy compounds
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Polyesters Or Polycarbonates (AREA)
Abstract
The invention discloses a method for preparing regenerated cationic dyeable polyester chips from waste polyester materials and provides a product thereof, wherein the method comprises the following steps: s1, pretreatment: drying and dewatering the waste polyester material; s2, heating and melting: feeding the dried waste polyester material into a double-screw system, melting and extruding the raw materials, and performing devolatilization and impurity removal on the molten waste polyester material to obtain a polyester melt; s3, depolymerization: the filtered polyester melt enters a depolymerization kettle to carry out depolymerization reaction with ethylene glycol, depolymerization is carried out to obtain a depolymerization liquid mixed by ethylene terephthalate (BHET) and ethylene glycol EG, and the yield of the ethylene terephthalate (BHET) in the depolymerization liquid reaches more than 98%; s4, polymerization reaction: and (3) evaporating the depolymerization liquid in a pre-polycondensation kettle at normal pressure to remove redundant ethylene glycol, adding SIPE solution to carry out copolymerization reaction, and then sending the solution into the polycondensation kettle to carry out polycondensation reaction to obtain the regenerated cation dyeable polyester slice. The invention has short process flow, high product yield, low energy consumption and cost and high product quality.
Description
Technical Field
The invention belongs to the technical field of high polymer materials, and particularly relates to a method for preparing regenerated cationic dyeable polyester chips from waste polyester materials and a product.
Background
The recycled PET sources in China are mainly divided into the following three categories: waste polyester beverage bottles, waste polyester packaging films, waste polyester filaments and waste textiles. Wherein the proportion of the waste polyester beverage bottles is still more than 60 percent.
At present, the recycling of waste polyester materials is mainly divided into two main types, namely a chemical method and a physical method. The physical method is the main method adopted at present in China. Traditional physical processes include direct opening and pelletizing spinning processes. The direct opening method is to open the polyester textile into short fibers and then spin the short fibers to produce a mop or a low-grade woolen blanket, which belongs to the lowest value utilization; the granulation spinning method is to process the polyester textile into a cloth soaking material, and then carry out melt spinning to produce common cotton type short fibers, and is the most common method applied at present. However, the physical method is difficult to avoid thermal degradation of polyester in the recycling process to cause viscosity reduction, and can not effectively remove impurities, and the performance of the regenerated polyester fiber is obviously lower than that of the original fiber.
The chemical process depolymerizes the waste polyester to small molecules such as terephthalic acid (TPA), dimethyl terephthalate (DMT), ethylene terephthalate (BHET), ethylene Glycol (EG). The small molecules can be used as polyester raw materials for repolymerization after purification to obtain regenerated polyester which is comparable to the original polyester, but in the prior art, because of the complexity of the components of the raw materials such as waste polyester materials of the polyester, a plurality of depolymerized byproducts are generated; in addition, the depolymerization process is not in place, and can not be completely depolymerized, so that the subsequent polymerization is influenced, the product quality does not reach the standard, and the commercialization cannot be realized at present.
Therefore, the technical personnel in the field urgently need to develop a method for preparing cationic dyeable polyester chips by using waste polyester materials as raw materials, and the method requires short process flow, high product yield, low energy consumption and cost and high quality of prepared products.
Disclosure of Invention
Aiming at the problems in the prior art, the invention aims to provide a method for preparing a regenerated cationic dyeable polyester chip from waste polyester materials and a product, which are short in process flow, high in product yield and low in energy consumption cost.
The invention provides a method for preparing regenerated cationic dyeable polyester chips from waste polyester materials, which adopts the following technical scheme:
a method for preparing regenerated cationic dyeable polyester chips from waste polyester materials comprises the following steps:
s1, pretreatment:
drying and dewatering the waste polyester material;
s2, heating and melting:
feeding the dried waste polyester material into a double-screw system, melting and extruding the raw materials, additionally arranging a vacuum system at the front end of the double-screw system, and devolatilizing and removing impurities from the molten waste polyester material to obtain a polyester melt;
s3, depolymerization:
feeding the polyester PET melt subjected to precision filtration into a depolymerization kettle to perform a full decomposition polymerization reaction with ethylene glycol, and depolymerizing to obtain a depolymerization solution mixed by ethylene terephthalate (BHET) and Ethylene Glycol (EG), wherein the yield of the BHET in the depolymerization solution is more than 98%;
s4, polymerization reaction:
and (3) evaporating the depolymerization liquid in a pre-polycondensation kettle at normal pressure to remove redundant ethylene glycol, adding SIPE solution to carry out copolymerization reaction, and then sending the solution into the polycondensation kettle to carry out polycondensation reaction to obtain the regenerated cation dyeable polyester slice.
The technical scheme adopts waste polyester materials (including waste polyester bottle chips, polyester waste silk, polyester waste textiles and the like) as raw materials, after pretreatment, water removal and impurity removal, BHET monomers are obtained through thorough depolymerization reaction, SIPE solution is added, and high-quality cationic dyeable polyester chips are polymerized again; the method has the advantages of short overall process route, low energy consumption cost, few byproducts, and less raw material consumption and fresh ethylene glycol, and the quality of the prepared product completely reaches the quality of filament yarn. Wherein, SIPE (sodium ethylene glycol isophthalate) solution is prepared by reacting a third monomer SIPM (dimethyl phthalate-5-sodium sulfonate) with EG (ethylene glycol).
Preferably, in step S1: the water content of the waste polyester material is controlled to be below 100ppm or between 100 and 200ppm by controlling a pre-crystallization drying system, wherein the drying temperature of the pre-crystallization drying system is 140 to 175 ℃, and the drying time is 4 to 8 hours.
Preferably, in step S2: controlling the heating temperature of the screw to be 255-285 ℃; and the waste polyester material is ensured to fully form a PET melt.
Preferably, in step S2: melting waste polyester materials, injecting ethylene glycol into the double-screw system, and controlling the addition of the ethylene glycol to be 0.2-1.5wt% of the melt so that the melt is subjected to viscosity reduction and homogenization in a double-screw cavity; the low-viscosity polyester melt is formed, so that subsequent filtration and impurity removal are facilitated, for example, a melt filter with the filtration precision of 100um can be adopted for filtration, a large amount of various impurities in the melt are preliminarily removed, and the reaction efficiency and reliability of subsequent process preparation are promoted.
Preferably, in step S3: controlling the reaction temperature in the depolymerization kettle at 180-235 deg.C, the reaction time at 0.05-0.15MPa for about 30-120 min; and/or; the weight ratio of the ethylene glycol to the PET melt after impurity removal is controlled to be between 1.4.
The embodiment enables ester bonds of polyester chains to be more easily broken under the action of ethylene glycol, more 1, 2 and 3 monomers of BHET can be obtained in the depolymerization process, more than 96 percent of the 1, 2 and 3 monomers of BHET account for the total amount, the alcoholysis reaction of PET and ethylene glycol can be more effectively promoted, the PET is thoroughly degraded, and most of components of products are BHET and oligomers thereof.
Preferably, in step S4: the normal pressure evaporation temperature is controlled to be 240-265 ℃, and the time is 20-50 minutes.
Further, in step S4: and (3) condensing and recovering the redundant evaporated glycol in the depolymerization reaction and small molecules in the polymerization reaction by a condenser of a pre-polycondensation kettle, and then rectifying the condensed and recovered glycol in an ethylene glycol distillation recovery system, wherein the absolute pressure in the ethylene glycol distillation recovery system is controlled to be between 8 and 16kpa, the distillation temperature is controlled to be between 140 and 170 ℃, and the obtained high-purity ethylene glycol enters the depolymerization kettle for recycling again. And the bottom of the distillation still is periodically discharged with residues which are sold for polyester paint raw materials and the like. The condensation and rectification step can remove diethylene glycol and part of impurities in the process, and the purified ethylene glycol is sent into the depolymerization kettle for recycling again.
Preferably, in step S4: after removing the redundant ethylene glycol in the pre-polycondensation kettle, firstly adding the ethylene glycol to cool BHET, and then adding SIPE solution to carry out copolymerization reaction to obtain the prepolymer.
Further, in step S4: adding glycol to reduce the temperature of BHET to 220-235 ℃, adding glycol solution of SIPE with the concentration of 40wt% to carry out copolymerization reaction, controlling the copolymerization reaction time to be 30-60 minutes, and controlling the addition of SIPE to be 1.5-3.0 wt% of BHET melt.
In step S3, the temperature of the mixed solution of BHET and EG entering the pre-polycondensation kettle is lower than 240 ℃, and the temperature of the mixed solution is required to be increased to about 240-265 ℃ if the excess EG in the mixed solution is evaporated out in a certain time under normal pressure. The copolymerization reaction of SIPE and BHET needs to be controlled at 220-235 ℃, a small amount of cold EG is added to achieve the cooling effect, and meanwhile, BHET monomers do not have depolymerization side reaction with EG. Therefore, the method is more favorable for obtaining high-quality polyester chips.
Preferably, in step S4: feeding the prepolymer after the copolymerization reaction into a polycondensation kettle, starting a low vacuum mode for the polycondensation kettle through a vacuum system, controlling the temperature to be 270-275 ℃, controlling the vacuum pressure to be 1-1.5 kpa absolute pressure, and controlling the reaction time in the polycondensation kettle to be 30-60 minutes to obtain a polycondensate;
and then starting a high vacuum mode for the polycondensate, controlling the temperature reduction point between 270 and 280 ℃ according to the final reaction temperature, and carrying out polycondensation reaction to obtain the regenerated cationic dyeable polyester chip when the viscosity in the polycondensation kettle reaches 0.56dl/g and the reaction temperature finally reaches 295-300 ℃.
The low vacuum mode is used for preventing excessive oligomer from being entrained into a vacuum pipeline to influence the operation of a vacuum system in the initial reaction stage. In the high vacuum mode, the temperature reduction point is the temperature of the polycondensation kettle when the heating medium temperature-raising valve of the polycondensation kettle is closed, that is, the temperature in the polycondensation kettle starts to be reduced, and the higher the vacuum degree in the high vacuum state is, the better the vacuum degree is.
In the embodiment, the prepolymer is subjected to continuous polycondensation to obtain the regenerated cationic dyeable polyester melt with high purity.
The invention also provides a regenerated cation dyeable polyester slice prepared by the method, which comprises the following components:
an intrinsic viscosity of 0.56 to 0.60dl/g (measured by a test method in which phenol: tetrachloroethane is 3;
the melting point is more than or equal to 249 ℃;
the content of terminal carboxyl is less than or equal to 35mol/t;
the L value is more than or equal to 70;
b is 2 to 4;
ash content is less than or equal to 0.4 percent.
The polyester chip prepared by the chemical method has higher quality, and the product performance has reliable guarantee.
In addition, in the preparation method provided by the invention, the flame retardant is added in the step S4, and the preparation method can also be applied to producing flame-retardant slices; in addition, the method can also be used for producing low-viscosity slices; the addition of the third monomer SIPM and the fourth monomer polyethylene glycol (PEG) in step S4 can also be applied to the production of low temperature cationic slices (ECDP).
The invention can bring the following beneficial effects:
1) The invention maintains the continuity and the simplicity of production through the sequential coordination of the steps of pretreatment, melting, viscosity reduction, filtration, depolymerization and polymerization; the ethylene glycol depolymerization process is adopted, so that depolymerization is more complete, most of products are BHET and oligomers thereof, the quality of products prepared by subsequent polymerization reaction is improved, and the method is suitable for large-scale commercial industrial production and has obvious economic value.
2) The process can also realize the repeated recycling of the raw material glycol, improves the recycling rate of resources, and is more energy-saving and environment-friendly.
3) The slice produced by the invention has excellent quality and lower cost, and the manufacturing cost of the chemical production process is further reduced.
Drawings
FIG. 1 is a schematic flow chart of the preparation method of the present invention.
The notations in the figures have the following meanings:
1-a pre-crystallization drying system; 2-a twin screw system; 3-a vacuum system; 4-depolymerization kettle; 5-pre-polycondensation kettle; 6-polycondensation kettle.
Detailed Description
The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.
The invention provides a method for preparing regenerated cationic dyeable polyester chips from waste polyester materials, which comprises the following steps:
s1, pretreatment:
drying and dewatering the waste polyester material;
s2, heating and melting:
feeding the dried waste polyester material into a double-screw system, melting and extruding the raw materials, additionally arranging a vacuum system (the vacuum degree can be preferentially set to be-0.98 MPa) at the front end of the double-screw system, and devolatilizing and removing impurities from the molten waste polyester material to obtain a polyester melt;
s3, depolymerization:
the reaction formula is as follows: PET + (n-1) EG → n BHET
The polyester melt after the precise filtration enters a depolymerization kettle to carry out full depolymerization reaction with ethylene glycol, depolymerization is carried out to obtain a depolymerization liquid mixed by ethylene terephthalate (BHET) and ethylene glycol EG, and the yield of the BHET in the depolymerization liquid reaches more than 98 percent;
s4, polymerization reaction:
the reaction formula is as follows: SIPE + BHET → CDP
And (3) evaporating the depolymerization liquid in a pre-polycondensation kettle at normal pressure to remove redundant ethylene glycol, adding SIPE solution to carry out copolymerization reaction, and then sending the solution into the polycondensation kettle to carry out polycondensation reaction to obtain the regenerated cation dyeable polyester slice.
As a preferred embodiment, in the step S1, the water content of the waste polyester material is controlled to be below 100ppm or between 100 and 200ppm by a pre-crystallization drying system, wherein the drying temperature of the pre-crystallization drying system is 140-175 ℃, and the drying time is 4-8 hours.
As another preferred embodiment, in step S2: the heating temperature of the screw is controlled to be 255-285 ℃.
As another preferred embodiment, in step S2: and injecting ethylene glycol into the double-screw system after the waste polyester material is molten, and controlling the addition of the ethylene glycol to be 0.2-1.5wt% of the melt so as to reduce and homogenize the viscosity of the melt in the double-screw cavity.
As another preferred embodiment, in step S3: controlling the reaction temperature in the depolymerization kettle at 180-235 deg.C, the reaction time at about 30-120min, and the pressure at 0.05-0.15MPa. And controlling the weight ratio of the ethylene glycol to the PET melt after impurity removal to be 1.4.
In addition, in the step S3, the normal pressure evaporation temperature is controlled to be 240-265 ℃, the time is 20-50 minutes, and the redundant glycol is convenient to evaporate and recycle. Preferably, the redundant evaporated glycol in the depolymerization reaction and the micromolecule formed in the polymerization reaction are condensed and recovered by a condenser of the pre-polycondensation kettle, and then enter an ethylene glycol distillation recovery system for rectification, the absolute pressure is controlled to be between 8kpa and 16kpa, the distillation temperature is controlled to be between 140 ℃ and 170 ℃, and the obtained high-purity ethylene glycol enters the depolymerization kettle for recycling again. And the bottom of the distillation still is periodically discharged with residues which are sold for polyester paint raw materials and the like. The condensation and rectification step can remove diethylene glycol and part of impurities in the process, and the purified ethylene glycol is sent into a depolymerization kettle for recycling again.
As another preferred embodiment, in step S4, 250ml to 450ml of ethylene glycol is added into the pre-polycondensation kettle for cooling, and SIPE solution is added after cooling for copolymerization reaction to obtain the prepolymer.
Preferably, in step S4: and cooling the pre-polycondensation kettle to 220-235 ℃, adding 40wt% of SIPE glycol solution for copolymerization, and controlling the copolymerization time to be 30-60 minutes, wherein the addition amount of SIPE is 1.5-3.0% of BHET melt.
As another preferred embodiment, the prepolymer after the copolymerization reaction is finished is sent into a polycondensation kettle, a low vacuum mode is started through a vacuum system, the temperature is controlled to be 270-275 ℃, the vacuum pressure is 1-1.5 kpa absolute, and the reaction time in the polycondensation kettle is controlled to be 30-60 minutes to obtain a polycondensate;
and starting a high vacuum mode for the polycondensate, controlling the temperature reduction point to be 270-280 ℃ according to the final reaction temperature, and carrying out polycondensation reaction to obtain the regenerated cationic dyeable polyester chip when the viscosity in the polycondensation kettle reaches 0.58dl/g and the reaction temperature finally reaches 295-300 ℃.
The quality indexes of the regenerated cationic dyeable polyester chip prepared by the method of the embodiment are as follows: the intrinsic viscosity is 0.58dl/g;
the melting point is more than or equal to 249 ℃;
the content of terminal carboxyl is less than or equal to 35mol/t;
the L value is more than or equal to 70;
b is 2 to 4;
ash content is less than or equal to 0.4.
Example 1
Referring to fig. 1, this embodiment is a method for preparing regenerated cationic dyeable polyester chips from waste polyester materials, including the following steps:
s1, pretreatment:
drying and dewatering the waste polyester material through a pre-crystallization drying system 1, wherein the drying temperature in the pre-crystallization drying system is 160 ℃, and the drying time is 6 hours, so as to control the water content of the waste polyester material to be below 100 ppm;
s2, heating and melting:
feeding the dried waste polyester material into a double-screw system 2, controlling the heating temperature of screws to be 265 ℃, melting and extruding the raw materials, additionally arranging a vacuum system 3 (the vacuum degree can be preferentially set to be-0.98 MPa) at the front end of the double screws, and performing devolatilization and impurity removal on the melted waste polyester material; melting waste polyester materials, then forcibly injecting Ethylene Glycol (EG), and controlling the addition of the ethylene glycol to be 0.7wt% of the melt, so that the melt is forcedly subjected to viscosity reduction (from 0.75 to about 0.35) and homogenization in a double-screw cavity to obtain a low-viscosity polyester melt, and more efficient filtration and impurity removal are conveniently carried out after the melt is discharged from a screw;
s3, depolymerization:
the low-viscosity polyester melt after the precise filtration enters a depolymerization kettle 4 to be subjected to full depolymerization reaction with ethylene glycol, the reaction temperature in the depolymerization kettle is controlled at 210 ℃, the reaction time is about 60min, and the pressure is controlled at 0.1Mpa; and controlling the weight ratio of the ethylene glycol to the PET melt after impurity removal to be 1.1; depolymerizing to obtain a depolymerized liquid mixed by ethylene terephthalate (BHET) and Ethylene Glycol (EG), wherein the yield of the ethylene terephthalate (BHET) in the depolymerized liquid reaches 100 percent, wherein one, two and three monomers of the BHET account for 96 percent of the total weight, and four, five and six monomers account for 4 percent of the total weight;
s4, polymerization reaction:
the depolymerization liquid is evaporated in a pre-polycondensation kettle at normal pressure, the normal pressure evaporation temperature is controlled to be 260 ℃, the time is 30 minutes, after redundant ethylene glycol is removed, BHET melt after the ethylene glycol is evaporated is further filtered and decontaminated through a monomer filter and enters a pre-polycondensation kettle 5, 350ml of ethylene glycol is added into the pre-polycondensation kettle for cooling, 60wt% of SIPE/ethylene glycol solution is added after the temperature is reduced to 228 ℃ for copolymerization reaction, the copolymerization reaction time is controlled to be 45 minutes, the addition amount of SIPE is 2% of the BHET melt, and a prepolymer is obtained through reaction; in step S3, the temperature of the mixed solution of BHET and EG in the pre-polycondensation reactor is about 210 ℃, and the temperature of the mixed solution is increased to about 260 ℃ if the excess EG is evaporated at normal pressure for a certain period of time. The copolymerization reaction of SIPE and BHET needs to be controlled at 228 ℃, a small amount of cold EG is added to achieve the cooling effect, and meanwhile, BHET monomer and EG do not have depolymerization side reaction. Thereby being more beneficial to obtaining high-quality polyester chips; feeding the prepolymer after the copolymerization reaction into a polycondensation kettle 6, starting a low vacuum mode through a vacuum system, controlling the temperature to be 272 ℃, controlling the vacuum pressure to be absolute pressure of 1.2kpa, and controlling the reaction time in the polycondensation kettle to be 45 minutes to obtain a polycondensate;
and starting a high vacuum mode for the polycondensate, controlling the temperature reduction point to be 275 ℃ according to the final reaction temperature, and carrying out polycondensation reaction to obtain the regenerated cationic dyeable polyester slice when the viscosity in the polycondensation kettle reaches 0.58dl/g and the reaction temperature finally reaches 298 ℃.
Wherein, after the depolymerization in the step S3, the ethylene glycol is evaporated, the redundant evaporated ethylene glycol and the micromolecules formed by the polymerization reaction are condensed and recovered by a condenser of the pre-polycondensation kettle 5, and then enter an ethylene glycol distillation recovery system (not shown in the figure) for rectification, the absolute pressure is controlled between 8kpa and 16kpa, the rectification temperature is controlled between 140 ℃ and 170 ℃, and the high-purity ethylene glycol is obtained and sent to the depolymerization kettle for recycling again.
The performance parameters of the obtained regenerated cationic dyeable polyester chip are as follows:
the intrinsic viscosity is 0.58dl/g; the melting point is 249 ℃; the content of terminal carboxyl groups is 31mol/t; l value is 75; the value of b is 2.5; the ash content was 0.1%.
Example 2
This example is substantially the same as example 1 except that:
s1, preprocessing: the drying temperature in the pre-crystallization drying system is 140 ℃, and the drying time is 8 hours, so that the water content of the waste polyester material is controlled to be below 100 ppm;
s2, during heating and melting: controlling the heating temperature of the screw to be 255 ℃; controlling the addition of the ethylene glycol to be 0.2wt% of the melt, so that the melt is forcedly subjected to viscosity reduction (from 0.75 to about 0.45) and homogenization in a double-screw cavity to obtain a low-viscosity polyester melt, and more efficient filtration and impurity removal are conveniently carried out after the melt is discharged from a screw;
s3, during depolymerization: controlling the reaction temperature in the depolymerization kettle at 180 ℃, the reaction time at about 120min and the pressure at 0.08Mpa; and controlling the weight ratio of the ethylene glycol to the PET melt after impurity removal to be 1.4; depolymerizing to obtain a depolymerization solution mixed by ethylene terephthalate (BHET) and Ethylene Glycol (EG), wherein the yield of the ethylene terephthalate (BHET) in the depolymerization solution reaches 100%, wherein the first monomer, the second monomer and the third monomer of the BHET account for 95% of the total amount, and the fourth monomer, the fifth monomer and the sixth monomer account for 5% of the total amount;
s4, in the polymerization reaction: controlling the normal pressure evaporation temperature of the depolymerization liquid to be 240 ℃ for 50 minutes, removing redundant ethylene glycol, then feeding the ethylene glycol into a pre-polycondensation kettle 5, adding 250ml of ethylene glycol into the pre-polycondensation kettle for cooling, adding 60wt% of SIPE/ethylene glycol solution after cooling to 220 ℃ for copolymerization reaction, controlling the copolymerization reaction time to be 60 minutes, controlling the addition of SIPE to be 1.5wt% of BHET melt, and reacting to obtain a prepolymer;
feeding the prepolymer after the copolymerization reaction into a polycondensation kettle 6, starting a low vacuum mode through a vacuum system, controlling the temperature to be 270 ℃, controlling the vacuum pressure to be absolute pressure of 1kpa, and controlling the reaction time in the polycondensation kettle to be 30 minutes to obtain a polycondensate;
and starting a high vacuum mode for the polycondensate, controlling the temperature reduction point at 270 ℃ according to the final reaction temperature, and carrying out polycondensation reaction to obtain the regenerated cationic dyeable polyester chip when the viscosity in the polycondensation kettle reaches 0.56dl/g and the reaction temperature finally reaches 295 ℃.
The performance parameters of the obtained regenerated cationic dyeable polyester chip are as follows:
the intrinsic viscosity is 0.56dl/g; the melting point is 248 ℃; the content of terminal carboxyl groups is 29mol/t; the value of L is 74; b is 4; the ash content was 0.1%.
Example 3
This example is substantially the same as example 1 except that:
s1, preprocessing: the drying temperature in the pre-crystallization drying system is 175 ℃, and the drying time is 4 hours, so that the water content of the waste polyester material is controlled to be below 100 ppm;
s2, in heating and melting: controlling the heating temperature of the screw to be 285 ℃; the addition amount of the ethylene glycol is controlled to be 1.5wt% of the melt amount, so that the melt is forcedly subjected to viscosity reduction (from 0.75 to about 0.3) and homogenization in a double-screw cavity to obtain a low-viscosity polyester melt, and more efficient filtration and impurity removal are facilitated after the melt is discharged from a screw;
s3, during depolymerization: controlling the reaction temperature in the depolymerization kettle at 235 ℃, the reaction time at about 30min, and the pressure at 0.15Mpa; and controlling the weight ratio of the ethylene glycol to the PET melt after impurity removal to be 0.8; depolymerizing to obtain a depolymerization solution mixed by ethylene terephthalate (BHET) and Ethylene Glycol (EG), wherein the yield of the ethylene terephthalate (BHET) in the depolymerization solution reaches 100%, wherein the first monomer, the second monomer and the third monomer of the BHET account for 97% of the total amount, and the fourth monomer, the fifth monomer and the sixth monomer account for 3% of the total amount;
s4, in the polymerization reaction: controlling the normal pressure evaporation temperature of the depolymerization liquid to be 265 ℃ for 20 minutes, removing redundant ethylene glycol, then feeding the ethylene glycol into a pre-polycondensation kettle 5, adding 450ml of ethylene glycol into the pre-polycondensation kettle for cooling, adding 60wt% of SIPE/ethylene glycol solution after cooling to 235 ℃ for copolymerization reaction, controlling the copolymerization reaction time to be 60 minutes, controlling the addition of SIPE to be 3wt% of BHET melt, and reacting to obtain a prepolymer;
feeding the prepolymer after the copolymerization reaction into a polycondensation kettle 6, starting a low vacuum mode through a vacuum system, controlling the temperature to be 275 ℃, controlling the vacuum pressure to be absolute pressure of 1.5kpa, and controlling the reaction time in the polycondensation kettle to be 60 minutes to obtain a polycondensate;
and starting a high vacuum mode for the condensation polymer, controlling the temperature reduction point at 270 ℃ according to the final reaction temperature, and carrying out polycondensation reaction to obtain the regenerated cationic dyeable polyester slice when the viscosity in the condensation kettle reaches 0.60dl/g and the reaction temperature finally reaches 300 ℃.
The performance parameters of the obtained regenerated cationic dyeable polyester chip are as follows:
the intrinsic viscosity is 0.60dl/g; the melting point is 252 ℃; the content of terminal carboxyl groups is 28mol/t; l is 78; b is 2.0; the ash content was 0.1%.
Comparative example 1
This example is substantially the same as example 1 except that:
s2, in heating and melting: controlling the heating temperature of the screw to be 250 ℃; the addition of the ethylene glycol is controlled to be 0.7wt% of the melt, so that the melt is forcedly subjected to viscosity reduction (from 0.75 to about 0.5) and homogenization in a double-screw cavity to obtain a low-viscosity polyester melt, and more efficient filtration and impurity removal are facilitated after the melt is discharged from a screw;
s3, during depolymerization: the low-viscosity polyester melt after the precise filtration enters a depolymerization kettle 4 to carry out full depolymerization reaction with ethylene glycol, the reaction temperature in the depolymerization kettle is controlled at 210 ℃, the reaction time is about 60min, and the pressure is controlled at 0.1Mpa; and controlling the weight ratio of the ethylene glycol to the PET melt after impurity removal to be 1.1; the depolymerization is carried out to obtain a depolymerization liquid mixed by the ethylene terephthalate BHET and the ethylene glycol EG, and the yield of the ethylene terephthalate BHET in the depolymerization liquid reaches 100 percent, wherein the first, second and third monomers of the BHET account for 92 percent of the total weight, and the fourth, fifth and sixth monomers account for 8 percent of the total weight.
The performance parameters of the obtained regenerated cationic dyeable polyester chip are as follows:
the intrinsic viscosity is 0.53dl/g; the melting point is 249 ℃; the content of terminal carboxyl groups is 30mol/t; the value of L is 70; the b value is 3.5; the ash content was 0.1%.
Comparative example 2
This example is substantially the same as example 2 except that:
s3, during depolymerization: controlling the reaction temperature in the depolymerization kettle at 180 ℃, the reaction time at about 120min and the pressure at 0.08MPa; and controlling the weight ratio of the ethylene glycol to the PET melt after impurity removal to be 1.5; depolymerizing to obtain a depolymerized liquid mixed by the BHET and the ethylene glycol EG, wherein the yield of the BHET in the depolymerized liquid reaches 100 percent, the first monomer, the second monomer and the third monomer of the BHET account for 95 percent of the total amount, and the fourth monomer, the fifth monomer and the sixth monomer account for 5 percent of the total amount.
The performance parameters of the obtained regenerated cationic dyeable polyester chip are as follows:
the intrinsic viscosity is 0.56dl/g; the melting point is 249 ℃; the content of terminal carboxyl groups is 31mol/t; the value of L is 71; the b value is 4.0; the ash content was 0.1%.
Comparative example 3
This example is substantially the same as example 3 except that:
step S3, depolymerization: controlling the reaction temperature in the depolymerization kettle at 235 ℃, the reaction time at about 90min, and the pressure at 0.15MPa; and controlling the weight ratio of the ethylene glycol to the PET melt after impurity removal to be 0.7; depolymerization is carried out to obtain a depolymerization solution mixed by the ethylene terephthalate BHET and the ethylene glycol EG, and the yield of the ethylene terephthalate BHET in the depolymerization solution reaches 100 percent, wherein the first monomer, the second monomer and the third monomer of the BHET account for 90 percent of the total weight, and the fourth monomer, the fifth monomer and the sixth monomer account for 10 percent of the total weight.
The performance parameters of the obtained regenerated cationic dyeable polyester chip are as follows:
the intrinsic viscosity is 0.52dl/g; the melting point is 248 ℃; the content of terminal carboxyl groups is 28mol/t; l value is 73; the b value is 3.8; the ash content was 0.1%.
It should be noted that the above embodiments can be freely combined as necessary. The foregoing is only a preferred embodiment of the present invention, and it should be noted that those skilled in the art can make various modifications and improvements without departing from the principle of the present invention, and these modifications and improvements should be considered as the protection scope of the present invention.
Claims (10)
1. A method for preparing regenerated cationic dyeable polyester chips from waste polyester materials is characterized by comprising the following steps:
s1, pretreatment:
drying and dewatering the waste polyester material;
s2, heating and melting:
feeding the dried waste polyester material into a double-screw system, melting and extruding the raw materials, additionally arranging a vacuum system at the front end of the double screws, and devolatilizing and removing impurities from the molten waste polyester material to obtain a polyester melt;
s3, depolymerization:
the filtered polyester PET melt enters a depolymerization kettle to carry out full depolymerization reaction with ethylene glycol, depolymerization is carried out to obtain a depolymerization solution mixed by ethylene terephthalate (BHET) and Ethylene Glycol (EG), and the yield of the BHET in the depolymerization solution is more than 98%;
s4, polymerization reaction:
and (3) evaporating the depolymerization liquid in a pre-polycondensation kettle at normal pressure to remove redundant ethylene glycol, adding SIPE solution to carry out copolymerization reaction, and then sending the solution into the polycondensation kettle to carry out polycondensation reaction to obtain the regenerated cation dyeable polyester slice.
2. The method according to claim 1, wherein in step S1:
the water content of the waste polyester material is controlled to be below 100ppm or between 100ppm and 200ppm by controlling a pre-crystallization drying system, wherein the drying temperature of the pre-crystallization drying system is 140 ℃ to 175 ℃, and the drying time is 4 to 8 hours.
3. The method according to claim 1, wherein in step S2:
controlling the heating temperature of the screw to be 255-285 ℃;
and/or;
and after melting the waste polyester material, injecting glycol into the double-screw system, and controlling the addition of the glycol to be 0.2-1.5wt% of the melt so as to reduce and homogenize the viscosity of the melt in the double-screw cavity.
4. The method according to claim 1, wherein in step S3:
controlling the reaction temperature in the depolymerization kettle at 180-235 deg.C, the reaction time at about 30-120min, and the pressure at 0.05-0.15MPa;
and/or;
the weight ratio of the ethylene glycol to the PET melt after impurity removal is controlled to be between 1.4 and 1 and 0.8.
5. The method of claim 1, wherein:
in step S4, the normal pressure evaporation temperature is controlled to be 240-265 ℃, and the time is 20-50 minutes.
6. The production method according to claim 5, characterized in that:
and (3) condensing and recovering redundant evaporated glycol in the depolymerization reaction and micromolecules in the polymerization reaction through a condenser of the pre-polycondensation kettle, and then rectifying in a glycol distillation recovery system, wherein the absolute pressure in the glycol distillation recovery system is controlled to be between 8 and 16kpa, the distillation temperature is controlled to be between 140 and 170 ℃, and the obtained high-purity glycol enters the depolymerization kettle for recycling again.
7. The method according to claim 1, wherein in step S4:
after removing the redundant ethylene glycol in the pre-polycondensation kettle, firstly adding the ethylene glycol to cool the BHET, and adding SIPE solution to carry out copolymerization reaction after cooling to obtain the prepolymer.
8. The method according to claim 7, wherein in step S4:
adding glycol to reduce the temperature of BHET to 220-235 ℃, adding glycol solution of SIPE with the concentration of 40wt% to carry out copolymerization reaction, controlling the copolymerization reaction time to be 30-60 minutes, and controlling the addition of SIPE to be 1.5-3.0 wt% of BHET melt.
9. The production method according to claim 1, characterized in that: in step S4:
feeding the prepolymer after the copolymerization reaction into a polycondensation kettle, starting a low vacuum mode on the polycondensation kettle through a vacuum system, controlling the temperature to be 270-275 ℃, controlling the vacuum pressure to be 1-1.5 kpa absolute pressure, and controlling the reaction time in the polycondensation kettle to be 30-60 minutes to obtain a polycondensate;
and starting a high vacuum mode for the polycondensate, controlling the temperature reduction point between 270 and 280 ℃ according to the final reaction temperature, and carrying out polycondensation reaction to obtain the regenerated cationic dyeable polyester chip when the viscosity in the polycondensation kettle reaches 0.56dl/g and the reaction temperature finally reaches 295 to 300 ℃.
10. A recycled cationic-dyeable polyester chip produced by the method of any one of claims 1 to 9, wherein the chip has:
the intrinsic viscosity is 0.56-0.60dl/g;
the melting point is more than or equal to 249 ℃;
the content of terminal carboxyl is less than or equal to 35mol/t;
the L value is more than or equal to 70;
b is 2 to 4;
ash content is less than or equal to 0.4.
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| CN107189044A (en) * | 2017-06-28 | 2017-09-22 | 树业环保科技股份有限公司 | A kind of method that discarded yarn fabric is prepared to the fiber polyester chip that can be applied to textile processing |
| CN107652422A (en) * | 2017-09-18 | 2018-02-02 | 浙江理工大学 | A kind of method that Waste Polyester alcoholysis method prepares cation regenerant dyeable polyester |
| CN108641120A (en) * | 2018-08-14 | 2018-10-12 | 上海聚友化工有限公司 | A kind of method and its recovery system of the recycling of waste and old polyester textile |
| CN110483279A (en) * | 2019-07-10 | 2019-11-22 | 福建赛隆科技有限公司 | A kind of recovery method of waste and old polyester material |
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| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN107189044A (en) * | 2017-06-28 | 2017-09-22 | 树业环保科技股份有限公司 | A kind of method that discarded yarn fabric is prepared to the fiber polyester chip that can be applied to textile processing |
| CN107652422A (en) * | 2017-09-18 | 2018-02-02 | 浙江理工大学 | A kind of method that Waste Polyester alcoholysis method prepares cation regenerant dyeable polyester |
| CN108641120A (en) * | 2018-08-14 | 2018-10-12 | 上海聚友化工有限公司 | A kind of method and its recovery system of the recycling of waste and old polyester textile |
| CN110483279A (en) * | 2019-07-10 | 2019-11-22 | 福建赛隆科技有限公司 | A kind of recovery method of waste and old polyester material |
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