CN117487143A - Preparation method of bottle-grade regenerated polyester chips - Google Patents
Preparation method of bottle-grade regenerated polyester chips Download PDFInfo
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- CN117487143A CN117487143A CN202311536939.5A CN202311536939A CN117487143A CN 117487143 A CN117487143 A CN 117487143A CN 202311536939 A CN202311536939 A CN 202311536939A CN 117487143 A CN117487143 A CN 117487143A
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- 229920000728 polyester Polymers 0.000 title claims abstract description 118
- 238000002360 preparation method Methods 0.000 title claims abstract description 28
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims abstract description 263
- 239000007788 liquid Substances 0.000 claims abstract description 111
- 238000006136 alcoholysis reaction Methods 0.000 claims abstract description 77
- QPKOBORKPHRBPS-UHFFFAOYSA-N bis(2-hydroxyethyl) terephthalate Chemical compound OCCOC(=O)C1=CC=C(C(=O)OCCO)C=C1 QPKOBORKPHRBPS-UHFFFAOYSA-N 0.000 claims abstract description 63
- 239000000178 monomer Substances 0.000 claims abstract description 41
- 238000006068 polycondensation reaction Methods 0.000 claims abstract description 41
- 238000001704 evaporation Methods 0.000 claims abstract description 36
- 230000008020 evaporation Effects 0.000 claims abstract description 36
- 239000002699 waste material Substances 0.000 claims abstract description 31
- 238000007670 refining Methods 0.000 claims abstract description 25
- 230000005855 radiation Effects 0.000 claims abstract description 23
- 239000010409 thin film Substances 0.000 claims abstract description 23
- YIMQCDZDWXUDCA-UHFFFAOYSA-N [4-(hydroxymethyl)cyclohexyl]methanol Chemical compound OCC1CCC(CO)CC1 YIMQCDZDWXUDCA-UHFFFAOYSA-N 0.000 claims abstract description 20
- 238000000926 separation method Methods 0.000 claims abstract description 20
- 239000007790 solid phase Substances 0.000 claims abstract description 19
- 239000012535 impurity Substances 0.000 claims abstract description 15
- 238000000199 molecular distillation Methods 0.000 claims abstract description 13
- 239000003054 catalyst Substances 0.000 claims description 34
- 239000000126 substance Substances 0.000 claims description 33
- 239000003381 stabilizer Substances 0.000 claims description 32
- 239000000203 mixture Substances 0.000 claims description 31
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 29
- 229910052799 carbon Inorganic materials 0.000 claims description 25
- 239000000463 material Substances 0.000 claims description 22
- 238000004519 manufacturing process Methods 0.000 claims description 21
- 238000002156 mixing Methods 0.000 claims description 21
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 17
- 238000006243 chemical reaction Methods 0.000 claims description 16
- 238000001816 cooling Methods 0.000 claims description 16
- 238000012691 depolymerization reaction Methods 0.000 claims description 16
- 239000011261 inert gas Substances 0.000 claims description 15
- 238000010438 heat treatment Methods 0.000 claims description 14
- 239000006185 dispersion Substances 0.000 claims description 11
- 150000001450 anions Chemical class 0.000 claims description 10
- 238000009835 boiling Methods 0.000 claims description 10
- 150000001768 cations Chemical class 0.000 claims description 10
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 claims description 10
- NWUYHJFMYQTDRP-UHFFFAOYSA-N 1,2-bis(ethenyl)benzene;1-ethenyl-2-ethylbenzene;styrene Chemical compound C=CC1=CC=CC=C1.CCC1=CC=CC=C1C=C.C=CC1=CC=CC=C1C=C NWUYHJFMYQTDRP-UHFFFAOYSA-N 0.000 claims description 9
- 230000009471 action Effects 0.000 claims description 9
- 230000035484 reaction time Effects 0.000 claims description 9
- 239000003957 anion exchange resin Substances 0.000 claims description 8
- 239000003729 cation exchange resin Substances 0.000 claims description 8
- 238000001035 drying Methods 0.000 claims description 8
- 239000000706 filtrate Substances 0.000 claims description 8
- 238000001914 filtration Methods 0.000 claims description 8
- 150000002500 ions Chemical class 0.000 claims description 8
- 229910052757 nitrogen Inorganic materials 0.000 claims description 8
- 229920000642 polymer Polymers 0.000 claims description 8
- 239000000047 product Substances 0.000 claims description 8
- 238000003756 stirring Methods 0.000 claims description 8
- HVLLSGMXQDNUAL-UHFFFAOYSA-N triphenyl phosphite Chemical compound C=1C=CC=CC=1OP(OC=1C=CC=CC=1)OC1=CC=CC=C1 HVLLSGMXQDNUAL-UHFFFAOYSA-N 0.000 claims description 8
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 claims description 7
- CDBYLPFSWZWCQE-UHFFFAOYSA-L Sodium Carbonate Chemical compound [Na+].[Na+].[O-]C([O-])=O CDBYLPFSWZWCQE-UHFFFAOYSA-L 0.000 claims description 6
- VXUYXOFXAQZZMF-UHFFFAOYSA-N titanium(IV) isopropoxide Chemical compound CC(C)O[Ti](OC(C)C)(OC(C)C)OC(C)C VXUYXOFXAQZZMF-UHFFFAOYSA-N 0.000 claims description 6
- VMHLLURERBWHNL-UHFFFAOYSA-M Sodium acetate Chemical compound [Na+].CC([O-])=O VMHLLURERBWHNL-UHFFFAOYSA-M 0.000 claims description 5
- 238000002425 crystallisation Methods 0.000 claims description 5
- 230000008025 crystallization Effects 0.000 claims description 5
- 235000011056 potassium acetate Nutrition 0.000 claims description 5
- 239000001632 sodium acetate Substances 0.000 claims description 5
- 235000017281 sodium acetate Nutrition 0.000 claims description 5
- IHLDFUILQQSDCQ-UHFFFAOYSA-L C(C)(=O)[O-].[Ge+2].C(C)(=O)[O-] Chemical compound C(C)(=O)[O-].[Ge+2].C(C)(=O)[O-] IHLDFUILQQSDCQ-UHFFFAOYSA-L 0.000 claims description 4
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 claims description 4
- WVLBCYQITXONBZ-UHFFFAOYSA-N trimethyl phosphate Chemical compound COP(=O)(OC)OC WVLBCYQITXONBZ-UHFFFAOYSA-N 0.000 claims description 4
- XZZNDPSIHUTMOC-UHFFFAOYSA-N triphenyl phosphate Chemical compound C=1C=CC=CC=1OP(OC=1C=CC=CC=1)(=O)OC1=CC=CC=C1 XZZNDPSIHUTMOC-UHFFFAOYSA-N 0.000 claims description 4
- 239000004246 zinc acetate Substances 0.000 claims description 4
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 3
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 claims 1
- 229910052787 antimony Inorganic materials 0.000 claims 1
- WATWJIUSRGPENY-UHFFFAOYSA-N antimony atom Chemical compound [Sb] WATWJIUSRGPENY-UHFFFAOYSA-N 0.000 claims 1
- 229910052719 titanium Inorganic materials 0.000 claims 1
- 239000010936 titanium Substances 0.000 claims 1
- MTHSVFCYNBDYFN-UHFFFAOYSA-N diethylene glycol Chemical compound OCCOCCO MTHSVFCYNBDYFN-UHFFFAOYSA-N 0.000 abstract description 94
- 238000000034 method Methods 0.000 abstract description 48
- 230000008569 process Effects 0.000 abstract description 24
- 230000008901 benefit Effects 0.000 abstract description 10
- 238000004064 recycling Methods 0.000 abstract description 9
- 239000002994 raw material Substances 0.000 abstract description 7
- 238000007664 blowing Methods 0.000 abstract description 5
- 238000007334 copolymerization reaction Methods 0.000 abstract description 5
- 238000004806 packaging method and process Methods 0.000 abstract description 5
- 238000010924 continuous production Methods 0.000 abstract description 2
- 239000002861 polymer material Substances 0.000 abstract description 2
- 230000001939 inductive effect Effects 0.000 abstract 1
- IKHGUXGNUITLKF-UHFFFAOYSA-N Acetaldehyde Chemical compound CC=O IKHGUXGNUITLKF-UHFFFAOYSA-N 0.000 description 14
- 238000006116 polymerization reaction Methods 0.000 description 13
- 238000007086 side reaction Methods 0.000 description 11
- WOZVHXUHUFLZGK-UHFFFAOYSA-N dimethyl terephthalate Chemical compound COC(=O)C1=CC=C(C(=O)OC)C=C1 WOZVHXUHUFLZGK-UHFFFAOYSA-N 0.000 description 10
- 239000010408 film Substances 0.000 description 10
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 description 9
- 238000005516 engineering process Methods 0.000 description 9
- 230000000694 effects Effects 0.000 description 8
- 238000007790 scraping Methods 0.000 description 8
- 238000002844 melting Methods 0.000 description 7
- 230000008018 melting Effects 0.000 description 7
- 230000006872 improvement Effects 0.000 description 6
- 230000014759 maintenance of location Effects 0.000 description 6
- -1 polyethylene terephthalate Polymers 0.000 description 5
- 229920000139 polyethylene terephthalate Polymers 0.000 description 5
- 239000005020 polyethylene terephthalate Substances 0.000 description 5
- 238000005809 transesterification reaction Methods 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
- KRXBVZUTZPDWQI-UHFFFAOYSA-N ethane-1,2-diol;titanium Chemical compound [Ti].OCCO KRXBVZUTZPDWQI-UHFFFAOYSA-N 0.000 description 4
- 239000012071 phase Substances 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- 238000011069 regeneration method Methods 0.000 description 4
- 238000004040 coloring Methods 0.000 description 3
- 238000009833 condensation Methods 0.000 description 3
- 230000005494 condensation Effects 0.000 description 3
- 239000012634 fragment Substances 0.000 description 3
- 239000001257 hydrogen Substances 0.000 description 3
- 229910052739 hydrogen Inorganic materials 0.000 description 3
- 239000003607 modifier Substances 0.000 description 3
- 238000001953 recrystallisation Methods 0.000 description 3
- 230000008929 regeneration Effects 0.000 description 3
- 238000000859 sublimation Methods 0.000 description 3
- 230000008022 sublimation Effects 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- WSXIMVDZMNWNRF-UHFFFAOYSA-N antimony;ethane-1,2-diol Chemical compound [Sb].OCCO WSXIMVDZMNWNRF-UHFFFAOYSA-N 0.000 description 2
- 230000009286 beneficial effect Effects 0.000 description 2
- 238000004042 decolorization Methods 0.000 description 2
- 230000007547 defect Effects 0.000 description 2
- 238000004821 distillation Methods 0.000 description 2
- 230000032050 esterification Effects 0.000 description 2
- 238000005886 esterification reaction Methods 0.000 description 2
- 230000006698 induction Effects 0.000 description 2
- 229920002521 macromolecule Polymers 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 230000000750 progressive effect Effects 0.000 description 2
- 229920006395 saturated elastomer Polymers 0.000 description 2
- 238000009987 spinning Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 125000000129 anionic group Chemical group 0.000 description 1
- PYKYMHQGRFAEBM-UHFFFAOYSA-N anthraquinone Chemical group CCC(=O)c1c(O)c2C(=O)C3C(C=CC=C3O)C(=O)c2cc1CC(=O)OC PYKYMHQGRFAEBM-UHFFFAOYSA-N 0.000 description 1
- 150000004056 anthraquinones Chemical group 0.000 description 1
- 125000000751 azo group Chemical group [*]N=N[*] 0.000 description 1
- 230000033228 biological regulation Effects 0.000 description 1
- 230000000903 blocking effect Effects 0.000 description 1
- YHWCPXVTRSHPNY-UHFFFAOYSA-N butan-1-olate;titanium(4+) Chemical compound [Ti+4].CCCC[O-].CCCC[O-].CCCC[O-].CCCC[O-] YHWCPXVTRSHPNY-UHFFFAOYSA-N 0.000 description 1
- 125000002091 cationic group Chemical group 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 150000001875 compounds Chemical class 0.000 description 1
- 229920001577 copolymer Polymers 0.000 description 1
- 239000013078 crystal Substances 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 239000000539 dimer Substances 0.000 description 1
- 229910001873 dinitrogen Inorganic materials 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000011156 evaluation Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000004744 fabric Substances 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 239000012467 final product Substances 0.000 description 1
- 239000006261 foam material Substances 0.000 description 1
- 125000000524 functional group Chemical group 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 230000003301 hydrolyzing effect Effects 0.000 description 1
- 125000002887 hydroxy group Chemical group [H]O* 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- 239000003456 ion exchange resin Substances 0.000 description 1
- 229920003303 ion-exchange polymer Polymers 0.000 description 1
- 238000011031 large-scale manufacturing process Methods 0.000 description 1
- 238000012423 maintenance Methods 0.000 description 1
- 229910044991 metal oxide Inorganic materials 0.000 description 1
- 150000004706 metal oxides Chemical class 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- IEQIEDJGQAUEQZ-UHFFFAOYSA-N phthalocyanine Chemical group N1C(N=C2C3=CC=CC=C3C(N=C3C4=CC=CC=C4C(=N4)N3)=N2)=C(C=CC=C2)C2=C1N=C1C2=CC=CC=C2C4=N1 IEQIEDJGQAUEQZ-UHFFFAOYSA-N 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 239000010865 sewage Substances 0.000 description 1
- 150000003384 small molecules Chemical class 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000001629 suppression Effects 0.000 description 1
- 239000012780 transparent material Substances 0.000 description 1
Classifications
-
- 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
- C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
- C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
- C08G63/16—Dicarboxylic acids and dihydroxy compounds
- C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
- C08G63/181—Acids containing aromatic rings
- C08G63/183—Terephthalic acids
-
- 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
- C08G63/78—Preparation processes
Landscapes
- 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 relates to a preparation method of bottle-grade regenerated polyester chips, belonging to the technical field of preparation of high polymer materials for packaging bottles. According to the invention, waste Polyester (PET) products are used as main raw materials, ethylene Glycol (EG) depolymerization and pre-impurity removal are carried out to obtain alcoholysis liquid, and then microwave radiation is used for inducing thin film evaporation separation and molecular distillation refining continuous process to prepare monomer liquid with the content of bis (2-hydroxyethyl) terephthalate (BHET) being more than or equal to 98.0 wt percent and the content of diethylene glycol (DEG) being 1.3-1.7wt%; and then adding 1, 4-cyclohexanedimethanol serving as a copolymerization component, and performing pre-polycondensation, final polycondensation and solid-phase polycondensation to obtain the bottle-grade regenerated polyester chip with good transparency and blowing plasticity, wherein the performance index reaches the superior grade of the original bottle-grade polyester chip. Compared with the preparation process of bottle grade regenerated polyester chips with the same quality, the method has the advantages of mild overall process parameters, short flow, good continuity, clean process and low consumption, and meanwhile, the method has the advantages of convenient EG internal recycling and obvious comprehensive efficiency advantage.
Description
Technical Field
The invention relates to a preparation method of bottle-grade regenerated polyester chips, belonging to the technical field of preparation of high polymer materials for packaging bottles.
Background
Polyester bottles are the most common variety in plastic packaging bottles, and have a proportion of more than 70% and a annual consumption of more than 800 ten thousand tons. The main raw material for preparing the polyester bottle is bottle grade Polyester (PET) slice, which is mainly polymerized by terephthalic acid, glycol and a certain amount of modified monomers by a direct esterification method, and the main structure is polyethylene terephthalate (PET, polyester for short). However, as polyester bottles are mostly quick consumer products, and the polyester bottles are depended on petroleum and not easy to degrade, the corresponding environmental resource problem is more and more serious, so that the preparation technology of bottle-grade recycled polyester is in great attention of industry.
Because the polyester for the packaging bottle has very high requirements on molecular weight, transparency and food safety, the only chemical regeneration method for realizing the regeneration preparation of bottle-grade polyester by taking waste polyester as a raw material at present is to depolymerize PET macromolecules to specific monomers which can be effectively separated from impurities and refined by specific chemical reaction, and then to re-polymerize the finished product pair-standard original PET macromolecules by taking the refined monomers as raw materials. The existing depolymerization method for PET recycling mainly comprises three types of hydrolytic polymerization, methanol depolymerization and glycol depolymerization, wherein the two types of depolymerization are compared with the other two types of depolymerization, and the depolymerization method has obvious advantages in the aspects of mildness of reaction conditions, safety of reaction, equipment manufacturing cost and operation and maintenance cost, so that the depolymerization method is favored by industry.
The existing preparation method of the regenerated polyester of the standard primary bottle grade still has the problems of long production flow, low efficiency and high consumption. The key to the improvement is, in the first place, how to more efficiently prepare depolymerized monomeric bis (2-hydroxyethyl) terephthalate BHET that can meet the needs of bottle grade polymerization. BHET is separated and refined from the mixture after EG depolymerization of waste PET, and the composition of the mixed system comprises: EG. BHET, oligomers (mainly dimers) inevitable from depolymerization equilibrium, EG self-polymerization side reaction product diethylene glycol (DEG), coloring and modifier fragments (mainly small molecules containing phthalocyanine, azo, anthraquinone structures), anions and cations (mainly polymerization and depolymerization all catalysts), filterable impurities (inorganic powders, metal oxides, other hybrid non-depolymerizing polymers). The separation and refining technology of BHET in the recycled glycol depolymerization system of the polyester mainly comprises the following steps:
the separation and refining of the BHET mentioned in the invention patents US4609608, US6630601 and CN104710601B are mainly realized based on the control of the solubility of the BHET, namely, the BHET in a system is subjected to cooling crystallization coarse separation, and then water is introduced for recrystallization refining. Although the purity of the BHET can be improved by the method, the temperature required by the recrystallization of the water phase of the BHET is far lower than the room temperature, the working procedure is long in time consumption and high in energy consumption, and the recycling difficulty of the solvent is also high. Moreover, for the system with high coloring and modifier fragments and anionic and cationic impurities, it is difficult to obtain BHET meeting the bottle-grade polymerization requirement even by repeated water phase recrystallization.
The invention patent WO2002/010117 firstly filters and removes filterable impurities, then uses activated carbon to adsorb and remove coloring and modifier fragments in the system, uses ion exchange resin to remove anion and cation impurities in the system, and then reduces the temperature of the BHET in the system for crystallization and separation to obtain crude BHET. For crude BHET, three-stage progressive refining process is adopted, namely, partial EG is removed firstly by reduced pressure distillation, then low-boiling-point substances are thoroughly removed by thin film evaporation under a higher vacuum state, and finally BHET is collected by high vacuum molecular distillation and condensation to finish refining. The three-stage progressive refining process can effectively inhibit side reactions, and the obtained refined BHET can meet the bottle-grade polymerization requirement. However, the whole process is too long, the efficiency is low, the complexity of the whole optimization control is high, and EG recycling is difficult. In order to further inhibit side reactions, the invention patent WO2003/101929 further carries out grading treatment on the evaporation process in a three-stage step-by-step refining link on the basis of WO2002/010117, and increases the control of the fraction to residue ratio in a molecular distillation link, so that the purity of the obtained refined BHET is higher, but the efficiency is not improved. The invention patent WO2022/003990 is based on WO2003/101929, and ethylene glycol monoether or diether compound with carbon number of 4-12 is introduced for extraction and decolorization, although the decolorization efficiency can be improved by homogeneous phase, the decolorizer with the chemical structure also tends to increase the separation difficulty from the alcoholysis agent ethylene glycol, and the recycling of the ethylene glycol and the decolorizer in the system is hindered. And meanwhile, the efficiency of integral separation and refining is improved.
Compared with the above WO2002/010117, WO2003/101929 and WO2022/003990 patents, the invention patent CN1135846441B adopts a separation and refining route with a thicker line to improve the efficiency, and the refining of the crude BHET is divided into two steps of removing low-boiling substances at a low vacuum degree and collecting the BHET by flash evaporation and condensation at a high temperature under a high vacuum degree, but the method does not mention the control of side reaction in the process and the actual purity of the BHET, only the obtained polyester can be subjected to spinning processing, and whether the product with relevant quality can be subjected to the standard original spinning grade PET chips is not described. Similarly, the invention patent CN107189044B also mentions only rectification for BHET refining and then direct polymerization, but also points out the need for adding toner, so that it can be judged that the improvement in efficiency obtained by such simplification measures is at the expense of quality, and there is still a problem that side reaction suppression is difficult.
The invention patent CN115894223A, CN116284710A proposes a method for creating sublimation conditions of BHET crystals to realize refining, and the process flow of the method is short, but the saturated vapor pressure of the BHET is very low due to strong intermolecular hydrogen bonding action of the BHET, so that the process window of sublimation refining of the BHET in a strict thermodynamic sense is very narrow, and large-scale production is difficult to realize. Based on large-scale sublimation refining, the more practical operation route is to convert crude BHET into dimethyl terephthalate (DMT) through transesterification with methanol, because DMT has no intermolecular hydrogen bonding effect, the saturated vapor pressure of DMT is far higher than that of BHET, large-scale refining can be completed relatively smoothly, then the refined DMT is converted into BHET through transesterification with glycol again, and then the polymerization is carried out to prepare the regenerated bottle-grade PET with original quality pair. The invention patent WO/2003/033581A1 and CN109503818A, CN110964188B, CN114437328A, CN114044892B, CN114149574B both contain regenerated polyester preparation technology developed based on the thought, but the method has the most obvious common defect that two transesterification reactions are introduced, so that the use of a catalyst is increased, and the process also involves highly flammable and volatile methanol management and recycling, and has long flow and high production cost.
On the other hand, the preparation of bottle grade regenerated polyester chips has high requirements on the purity of regenerated BHET, and also has certain special requirements on the molecular structure of the final product, and the polyester applied to packaging bottles needs to have better blowing plasticity and transparency, and the blowing property needs to have high enough PET molecular weight and needs to be realized by solid phase polycondensation. In the aspect of transparency, a certain amount of crystallization-retarding structures are required to be contained in the PET macromolecular structure, and the preparation of the virgin bottle-grade polyester can realize specific adjustment of the PET macromolecular structure by jointly esterifying terephthalic acid, ethylene glycol and a modified monomer through a direct esterification process route and further copolycondensation. However, in the case of the regenerative production, high-purity BHET is usually used as a polymerization starting point, and since there is no process of co-esterifying with the modified monomer, it is difficult to form a copolymer structure satisfying the bottle demand even if the modified monomer is added for copolycondensation.
Disclosure of Invention
Aiming at the defects in the prior art, the invention aims to prepare a monomer liquid with the content of bis (2-hydroxyethyl) terephthalate (BHET) being more than or equal to 98.0 wt percent and the content of diethylene glycol (DEG) being 1.3-1.7wt% by taking waste Polyester (PET) products as main raw materials, depolymerizing Ethylene Glycol (EG) and pre-removing impurities to obtain alcoholysis liquid, and then carrying out microwave radiation-induced thin film evaporation separation and molecular distillation refining continuous processes. And adding 1, 4-cyclohexanedimethanol serving as a copolymerization component into the monomer liquid, and performing pre-polycondensation, final polycondensation and solid-phase polycondensation to obtain the bottle-grade regenerated polyester chip, wherein the performance index reaches the superior grade of the original bottle-grade polyester chip. Compared with the preparation process of bottle grade regenerated polyester chips with the same quality, the method has the advantages of mild overall process parameters, short flow, good continuity, clean process and low consumption, and meanwhile, the method has the advantages of convenient EG internal recycling and obvious comprehensive efficiency advantage.
The invention realizes the aim through the following technical scheme:
the preparation method of the bottle grade regenerated polyester chip is characterized by comprising the following steps:
1) Uniformly mixing waste polyester materials, EG, a catalyst, a stabilizer and active carbon according to a certain proportion, feeding the mixture to an alcoholysis device, uniformly stirring the mixture for depolymerization reaction for 2-5 hours under the protection of inert gas at the temperature of 185-200 ℃ and the pressure of 100-200 kPa, filtering the mixture at the temperature of 60-100 ℃ to remove the active carbon and other filterable impurities, maintaining the filtrate at the temperature of 60-100 ℃, sequentially flowing through cation exchange resin and anion exchange resin for ion removal and subtraction until the total concentration of anions and cations is less than or equal to 50 ppm, and recording the obtained liquid as alcoholysis liquid.
2) Preheating the alcoholysis solution obtained in the step 1) to 110-120 ℃ under the protection of inert gas, transferring the alcoholysis solution into a scraper type thin film evaporator with microwave radiation, and performing microwave radiation-induced thin film evaporation treatment to remove substances with boiling point lower than BHET in the alcoholysis solution; controlling the air pressure in the thin film evaporation cavity to be 200-300 Pa through a vacuum system, controlling the residence time of the alcoholysis liquid on the evaporation surface under the action of microwave irradiation to be 20-100 s through the feeding flow and the scraper rotating speed, and controlling the temperature of the finished liquid at 160-165 ℃ through a microwave power control concentration outlet to obtain concentrated finished liquid with EG less than 0.1wt% and DEG content of 0.8-1.2 wt% as separating liquid; meanwhile, condensing and collecting the low-boiling-point substances removed in the step, transferring the low-boiling-point substances to a conventional rectification separation device, and obtaining EG with purity more than or equal to 99.0 and wt% by conventional rectification separation, wherein the EG is recorded as recovered EG.
3) Transferring the separating liquid obtained in the step 2) to a molecular distillation device, and maintaining the mass ratio of distillate to residue at 6.9:3.1-7.4:2.6 by controlling the residence time of the separating liquid on a heating surface at the temperature of 210-215 ℃ and the pressure of less than or equal to 25 Pa and the temperature of a condensing surface at 110-120 ℃; the main component of the obtained residue is oligomer, which is marked as alcoholysis refining residue, and the alcoholysis refining residue is collected and transferred to the alcoholysis device in the step 1) to participate in depolymerization reaction in the next production period; the distillate is recorded as monomer liquid, the BHET content of the monomer liquid is more than or equal to 98.0wt% and the DEG content is 1.3-1.7 wt%.
4) Uniformly mixing the monomer liquid obtained in the step 3) with a 1, 4-cyclohexanedimethanol dispersion liquid containing a certain amount of catalyst and stabilizer at 170 ℃ according to a certain proportion under the protection of nitrogen at the temperature of 170-180 ℃ and the pressure of 101kPa, transferring the mixture to a pre-polycondensation reaction kettle at the temperature of 250-255 ℃ for 1.5-2.5 hours, keeping the pressure in the kettle at 101kPa at the beginning, keeping the pressure unchanged for 0.5-1 hour, and then linearly reducing the pressure to 1kPa from 101kPa along with the reaction time; then transferring the mixture into a final shrinkage reaction kettle, reacting for 1.5-2.0 h at the temperature of 270-290 ℃ and the pressure of 20-50 Pa, cooling, granulating and drying the obtained melt, and obtaining a basic slice with the intrinsic viscosity of 0.60-0.62 dL/g; and (3) the basic slice is subjected to pre-crystallization and preheating to the solid phase polycondensation reaction temperature, then is transferred to a solid phase polycondensation reactor, is reacted for 12-24 hours at the temperature of 200-220 ℃, and is cooled to finish the reaction, so that the bottle-grade regenerated polyester slice is obtained.
As described aboveThe preparation method of the regenerated polyethylene terephthalate comprises the steps that in the step 1), the waste polyester material is a post-consumer polyester product or production waste with PET component content more than or equal to 85wt%, preferably 95 wt percent; the EG is a mixture of polyester polymer grade EG and recovered EG obtained in the step 2) according to the ratio of 1:0.1-1:1; the catalyst is one of sodium carbonate, zinc acetate, tetrabutyl titanate and tetraisopropyl titanate; the stabilizer is one of sodium acetate and potassium acetate; the specific proportion is that based on the mass of PET contained in the waste polyester material, the EG addition amount is 200-400 wt%, the catalyst addition amount is 0.5-1.5 wt% and the stabilizer addition amount is 0.5-5 multiplied by 10 -2 The weight percentage of the active carbon is 1-5wt%.
The method for preparing bottle grade regenerated polyethylene terephthalate, wherein the scraper type thin film evaporator with microwave radiation in the step 2) is characterized in that: the microwave is generated by a microwave generator with adjustable power and is transmitted into the cavity of the evaporator through the waveguide connected with the inner wall of the evaporator, the inner wall of the evaporator and the rotor scraping plate are made of microwave transparent materials, the gap between the rotor scraping plate and the inner wall of the evaporator is 0.5-2 mm, the microwave reflection blocking and heat insulation treatment are respectively carried out on each interface part and the outer wall of the inner wall, and the evaporation gas phase condensation system and the concentrated solution collection system which are communicated through the interfaces are all positioned outside the cavity formed by the liquid film and are not affected by microwave radiation.
The preparation method of the bottle grade regenerated polyethylene terephthalate comprises the following steps: the catalyst is 100-1000 ppm, and the stabilizer is 200-1000 ppm; the catalyst is one of ethylene glycol titanium, ethylene glycol antimony or germanium acetate; the stabilizer is one of trimethyl phosphate, triphenyl phosphate or triphenyl phosphite; the mixing ratio of the monomer liquid to the 1, 4-cyclohexanedimethanol dispersion liquid at 170 ℃ is 93:7-98:2; the evaluation of the performance quality of the obtained bottle grade recycled polyester was performed according to the national standard of the people's republic of China GB/T179331-2018 (polyester chip for bottle (PET)).
The essential features and related principles of the present invention are described below:
the invention provides a preparation method of bottle-grade regenerated polyethylene terephthalate (PET), which is mainly characterized in that: the method can be used for efficiently obtaining high-purity BHET from alcoholysis liquid obtained by a glycol depolymerization method, and simultaneously controlling the DEG content to be just in the high-purity BHET so that the BHET and 1, 4-cyclohexanedimethanol with the addition amount of 2-7wt% form a more sufficient copolymerization structure, and ensuring that a chain segment has better activity and thermal stability under solid-phase polycondensation so as to meet the application requirements of bottle processing, namely efficiently preparing monomer liquid with the BHET content of more than or equal to 98.0wt% and the DEG content of 1.3-1.7wt%. On the basis, the copolymerization component 1, 4-cyclohexanedimethanol is added into the monomer liquid, and after the processes of pre-polycondensation, final polycondensation and solid phase polycondensation, the preparation of the bottle grade regenerated polyester chips with the standard original quality can be realized.
The reason that the monomer liquid can be efficiently and stably prepared is that: firstly, the basic components (components are: EG. DEG, BHET and oligomer), on the basis of which the combined advantages are formed by combining film evaporation with microwave radiation induction in the step 2), according to the fact that molecules with different polarities have different wave absorption capacities and kinetic energy conversion characteristics, the comprehensive improvement of separability and separability controllability of each component in the alcoholysis liquid is realized by combining film evaporation which can minimize diffusion limitation. Meanwhile, as the microwave can promote the relaxation and fracture of hydrogen bonds among molecules, separation and entrainment among EG, DEG and BHET components can be effectively avoided in the process, and side reactions such as self-polymerization of EG into DEG, transesterification between DEG and BHET and the like in the separation process are inhibited. Compared with the conventional thin film evaporation treatment, the method does not need to undergo time-consuming processes such as stepwise gradual evaporation and the like to avoid entrainment and side reactions, and can realize the efficient and controllable removal of low-boiling-point substances in one step. And then separating the oligomer by molecular distillation in the step 3), and extracting light components in the process to realize high-efficiency refining of the monomer. Based on the principle, the efficient and stable preparation of the monomer liquid can be realized under the comprehensive control of the process parameter ranges of the step 1), the step 2) and the step 3) by combining the practice of the system.
On the other hand, the DEG content of 1.3-1.7wt% is favorable for the BHET to form a more sufficient copolymerization structure with the 1, 4-cyclohexanedimethanol with the addition amount of 2-7wt%, and the reason for ensuring that the chain segment has better activity and thermal stability under solid phase polycondensation is that: in principle, during transesterification, DEG and EG are closer in terms of functional group activity, and can enter the main chain more easily and uniformly than 1, 4-cyclohexanedimethanol, while the DEG segment entering the molecular chain has higher flexibility than the EG segment, and can enable the ester bond of the main chain to form better contact with the hydroxyl group of 1, 4-cyclohexanedimethanol, so that DEG can better help 1, 4-cyclohexanedimethanol enter the main chain uniformly, and further high transparency is obtained; meanwhile, the existence of the DEG chain segment also increases the activity capability of a molecular chain, is more beneficial to the improvement of the solid-phase polycondensation quality, and obtains better blowing plasticity. In effect, the system practice determines that DEG must be in the content range to properly exert the ideal effect, namely, the success rate and uniformity of the 1, 4-cyclohexanedimethanol in the addition amount range entering a macromolecular chain can be obviously improved, and high transparency is obtained; and the basic slice obtained after the pre-polycondensation and the final polycondensation has proper molecular activity and thermal stability (when DEG is lower than the value, the solid phase polycondensation speed is slow, the intrinsic viscosity cannot reach the standard, and when DEG is higher than the value, the stability is reduced, the melting point, the hue and the acetaldehyde content cannot reach the standard), the efficient and stable tackifying of the solid phase polycondensation is ensured, the final slice has good transparency and blowing plasticity, and the performance index reaches the superior grade of the original bottle grade polyester slice. Therefore, the preparation of the bottle-grade regenerated polyester chips with the standard original quality can be finally realized through the step 4) on the basis that the monomer liquid can be efficiently and stably prepared, which cannot be achieved by the prior regeneration polymerization process.
In the disclosed bottle grade recycled polyester preparation technologies CN111138641a, CN112759746B, and the related PET alcoholysis monomer purification technologies described above, the use of microwave radiation induction is not involved, and the specific regulation and control of DEG content in the bottle grade recycled polymerization is not synchronously realized in the process of purifying the monomers. In the next-related polyester ethylene glycol depolymerization method, only patent CN108602974B, CN112940344a mentions the utilization of microwave radiation means, the aim is only to accelerate the depolymerization process, no operation related to microwaves is involved in the depolymerization monomer purification link, and the technical scheme of the invention is essentially different from that of the invention, so the technical scheme of the invention in the prior art has no technical teaching.
Compared with the background technology, the method has a shorter and more efficient flow, the process does not need to undergo complicated and time-consuming steps such as cooling crystallization, crude BHET multistage evaporation gradual concentration and the like which are necessary to avoid the problems of evaporation separation entrainment, side reaction and the like, and based on the remarkable improvement of the separation precision and the adjustable performance of substances in alcoholysis liquid, the method can synchronously realize the blind improvement of the purity of the BHET, and is changed into film-oriented base material application, and the DEG content in the BHET is controlled specifically, so that the method is more economical, efficient and stable. In addition, because the distillation of low boiling point substances is concentrated and the side reaction is small in the process, the EG can be recycled in the system more easily compared with the background technology, and the raw material consumption is low; the alcoholysis refining residues generated in the step 3) are transferred to an alcoholysis device to participate in the operation of depolymerization reaction in the next production cycle, so that on one hand, the solubility of the waste polyester material in a depolymerization system can be improved due to similar compatibility, the reaction can be more quickly brought into a homogeneous state, the reaction time required by depolymerization in the step 1) is obviously shortened, side reactions are reduced, and meanwhile, the recycling yield can be improved.
The beneficial effects of the invention are as follows:
(1) The preparation method of the regenerated bottle-grade PET provided by the invention can solve the problems of long flow, poor continuity, more side reactions and low purity and yield in the direct separation and refining process of BHET in alcoholysis liquid based on a gas-liquid equilibrium separation method at present. Meanwhile, the content of the monomer liquid BHET of the refining link product can be controlled to be more than or equal to 98.0wt%, the DEG content is 1.3-1.7 wt%, the specific requirements of bottle-grade PET preparation are just met, and compared with the background technology, the production process can be obviously shortened under the condition of ensuring high-quality output of the product, and the method is more efficient and economical.
(2) Compared with the background technology, the preparation method of the regenerated bottle-grade PET provided by the invention is easier to realize high-efficiency and full recycling of EG and oligomer residues in the production process. Meanwhile, the separation precision and the adjustable performance of substances in the alcoholysis liquid are obviously improved based on the invention, and the conversion from blind high-purity monomer purification to controllable monomer purification aiming at the specific requirement of bottle-level regeneration is realized. The method can obviously reduce the cost of raw materials and sewage disposal, and is cleaner and lower in consumption.
(3) The preparation method of the regenerated bottle-grade PET provided by the invention has the advantages of mild overall technological parameter requirements, short flow, good continuity, moderate investment cost of production equipment, obvious comprehensive performance advantage and good industrial application prospect.
The technical scheme of the invention is further described below in connection with specific embodiments.
Example 1
1) Uniformly mixing waste polyester material, EG, a catalyst, a stabilizer and active carbon according to a certain proportion, feeding the mixture to an alcoholysis device, uniformly stirring the mixture to react for 5 h under the protection of nitrogen gas at 185 ℃ and 100kPa, filtering the mixture at 75 ℃ to remove active carbon and other filterable impurities, maintaining the filtrate at 75 ℃, sequentially flowing through cation exchange resin and anion exchange resin to carry out ion removal, wherein the total concentration of anions and cations in the obtained liquid is 25 ppm, and marking the obtained liquid as alcoholysis liquid.
Wherein the waste polyester material is waste polyester bottle flakes with the PET component content of 98.5 weight percent; the EG is polyester polymer grade EG and EG recovered in the step 2) according to a mixture of 1:0.1; the catalyst is tetra-n-butyl titanate; the stabilizer is potassium acetate; the proportion is based on PET mass, EG addition amount is 400 wt%, catalyst addition amount is 1.5 wt%, stabilizer addition amount is 5×10 -2 The addition amount of the activated carbon is 1 wt percent by weight.
2) And (2) preheating the alcoholysis solution obtained in the step (1) to 120 ℃ under the protection of inert gas, transferring the alcoholysis solution into a scraper type thin film evaporator with microwave radiation, and performing microwave radiation-induced thin film evaporation treatment to remove substances with boiling point lower than BHET in the alcoholysis solution, wherein the gap between a rotor scraper and the inner wall of the evaporator is 2 mm. In the treatment, the air pressure in the film evaporation cavity is controlled to be 200 Pa through a vacuum system, the retention time of an evaporation surface of the alcoholysis liquid under the action of microwave irradiation is controlled to be 100 s through the feeding flow and the rotating speed of a scraping plate, the temperature of the finished liquid at a concentration outlet is controlled to be 160 ℃ through microwave power, the EG content in the concentrated finished liquid is 0.04 wt%, the DEG content is 1.2 wt%, and the concentrated finished liquid is recorded as a separating liquid; and condensing and collecting the low-boiling-point substances removed in the step, and transferring the low-boiling-point substances to a conventional rectifying and separating device to obtain EG with purity of 99.2 and wt percent, which is recorded as recovered EG.
3) Transferring the separating liquid obtained in the step 2) to a molecular distillation device, and controlling the residence time of the separating liquid on a heating surface to be 100 s at the temperature of 215 ℃ on the heating surface and the pressure of 16 Pa and the temperature of 110 ℃ on a condensing surface so as to stabilize the mass ratio of distillate to residue at 7.4:2.6. The main component of the obtained residue is oligomer, which is marked as alcoholysis refined residue, collected and transferred into an alcoholysis device to participate in depolymerization reaction of the next production period; the distillate obtained was designated as monomer liquid, which had a BHET content of 98.0wt% and a DEG content of 1.7. 1.7 wt%.
4) Uniformly mixing the monomer liquid obtained in the step 3) with a dispersion liquid of 1, 4-cyclohexanedimethanol containing 100 ppm of ethylene glycol titanium and 1000ppm of triphenyl phosphate at 170 ℃ according to the mass ratio of 93:7, uniformly mixing at 170 ℃, under the protection of 101 kPa and nitrogen, maintaining the temperature, transferring to a pre-polycondensation reaction kettle, reacting at 250 ℃ for 2.5h, firstly maintaining the pressure of 1 h at 101 kPa at the beginning, and then linearly reducing the pressure to 1 kPa along with the reaction time from 101 kPa; then transferring into a final polycondensation reaction kettle, cooling, granulating and drying the obtained melt at 270 ℃ and 20Pa for reaction 2 h to obtain a basic slice with the intrinsic viscosity of 0.60 dL/g; the basic slice is transferred to a solid phase polycondensation reactor after being pre-crystallized and preheated to 200 ℃, reacts for 24 hours at 200 ℃, and after cooling, the bottle grade regenerated polyester slice is obtained, wherein the intrinsic viscosity is 0.852+/-0.008 dL/g, the melting point is 241.3+/-1.0 ℃, the hue L/b value is 81.3/1.94+/-0.09, and the acetaldehyde content is 0.37 mug/g.
Example 2
1) Uniformly mixing waste polyester material, EG, a catalyst, a stabilizer and active carbon according to a certain proportion, feeding the mixture to an alcoholysis device, carrying out depolymerization reaction 2 h under the protection of inert gas and uniform stirring at the temperature of 200 ℃ and the pressure of 200kPa, filtering at the temperature of 85 ℃ to remove active carbon and other filterable impurities, maintaining the filtrate at the temperature of 85 ℃, sequentially flowing through cation exchange resin and anion exchange resin to carry out ion removal, wherein the total concentration of anions and cations in the obtained liquid is 50 ppm, and marking the obtained liquid as alcoholysis liquid.
Wherein the waste polyester material is waste polyester bottle flakes with the PET component content of 95.8 wt%; the EG is polyester polymerization grade EG and EG recovered in the step 2) according to a 1:1 mixture; the catalyst is sodium carbonate; the stabilizer is sodium acetate; the proportion is based on PET mass, EG addition amount is 200 wt%, catalyst addition amount is 0.5 wt%, stabilizer addition amount is 0.5×10 -2 The weight percent of the active carbon is 3 weight percent.
2) And (2) preheating the alcoholysis solution obtained in the step (1) to 110 ℃ under the protection of inert gas, transferring the alcoholysis solution into a scraper type thin film evaporator with microwave radiation, and performing microwave radiation-induced thin film evaporation treatment to remove substances with boiling point lower than BHET in the alcoholysis solution, wherein the gap between a rotor scraper and the inner wall of the evaporator is 0.5 mm. In the treatment, the air pressure in the film evaporation cavity is controlled to be 300 Pa through a vacuum system, the retention time of an evaporation surface of the alcoholysis liquid under the action of microwave irradiation is controlled to be 20 s through the feeding flow and the rotating speed of a scraping plate, the temperature of the finished liquid at a concentration outlet is controlled to be 165 ℃ through microwave power, the EG content in the concentrated finished liquid is 0.01 wt%, the DEG content is 0.8 wt%, and the concentrated finished liquid is recorded as a separating liquid; and condensing and collecting the low-boiling-point substances removed in the step, and transferring the low-boiling-point substances to a conventional rectifying and separating device to obtain EG with purity of 99.4 and wt percent, which is recorded as recovered EG.
3) Transferring the separating liquid obtained in the step 2) to a molecular distillation device, and controlling the residence time of the separating liquid on a heating surface to be 80 s at the temperature of 210 ℃ and the pressure of 23 Pa on the heating surface and the temperature of 120 ℃ on a condensing surface so as to stabilize the mass ratio of distillate to residue at 6.9:3.1. The main component of the obtained residue is oligomer, which is marked as alcoholysis refined residue, collected and transferred into an alcoholysis device to participate in depolymerization reaction of the next production period; the distillate obtained was designated as monomer liquid, which had a BHET content of 98.5wt% and a DEG content of 1.3 wt%.
4) Uniformly mixing the monomer liquid obtained in the step 3) with a dispersion liquid of 1, 4-cyclohexanedimethanol containing 1000 ppm of germanium acetate and 200ppm of trimethyl phosphate at 170 ℃ according to the mass ratio of 98:2 under the protection of 180 ℃ and 101 kPa and nitrogen, transferring the mixture to a pre-polycondensation reaction kettle at the temperature of 255 ℃ for 1.5 hours, keeping the pressure of 0.5 h at 101 kPa at the beginning, and then linearly reducing the pressure to 1 kPa along with the reaction time from 101 kPa; then transferring into a final polycondensation reaction kettle, cooling, granulating and drying the obtained melt at 290 ℃ and 50Pa for reaction of 1.5 and h to obtain a basic slice with the intrinsic viscosity of 0.62 dL/g; the basic slice is transferred to a solid phase polycondensation reactor after being pre-crystallized and preheated to 220 ℃, reacts for 12 hours at 220 ℃, and after cooling, the bottle grade regenerated polyester slice is obtained, wherein the intrinsic viscosity is 0.849+/-0.007 dL/g, the melting point is 247.8+/-1.1 ℃, the hue L/b value is 84.5/0.84+/-0.05, and the acetaldehyde content is 0.25 mug/g.
Example 3
1) Uniformly mixing waste polyester material, EG, a catalyst, a stabilizer and active carbon according to a certain proportion, feeding the mixture to an alcoholysis device, carrying out depolymerization reaction for 3.5 h under the protection of inert gas and uniform stirring at the temperature of 195 ℃ and the pressure of 150kPa, filtering to remove active carbon and other filterable impurities at the temperature of 60 ℃, maintaining the filtrate at the temperature of 60 ℃, sequentially passing through cation exchange resin and anion exchange resin to carry out ion removal, wherein the total concentration of anions and cations in the obtained liquid is 22 ppm, and recording as alcoholysis liquid.
Wherein the waste polyester material is waste polyester bottle flakes with the PET component content of 97.4 weight percent; the EG is polyester polymer grade EG and EG recovered in the step 2) according to a mixture of 1:0.5; the catalyst is zinc acetate; the stabilizer is potassium acetate; the proportion is based on PET mass, EG addition amount is 300wt%, catalyst addition amount is 0.8wt%, and stabilizer addition amount is 4×10 -2 The weight percent of the active carbon is 4 weight percent.
2) And (2) preheating the alcoholysis solution obtained in the step (1) to 116 ℃ under the protection of inert gas, transferring the alcoholysis solution into a scraper type thin film evaporator with microwave radiation, and performing microwave radiation-induced thin film evaporation treatment to remove substances with boiling point lower than BHET in the alcoholysis solution, wherein the gap between a rotor scraper and the inner wall of the evaporator is 1.5 mm. In the treatment, the air pressure in the film evaporation cavity is controlled to be 250Pa through a vacuum system, the retention time of an alcoholysis solution on an evaporation surface under the action of microwave irradiation is controlled to be 60 s through the feeding flow and the rotating speed of a scraping plate, the temperature of a finished solution at a concentration outlet is controlled to be 162 ℃ through microwave power, the EG content in the concentrated finished solution is 0.03wt%, the DEG content is 1.0wt%, and the concentrated finished solution is recorded as a separating solution; and condensing and collecting the low-boiling-point substances removed in the step, and transferring the low-boiling-point substances to a conventional rectifying and separating device to obtain EG with the purity of 99.3wt%, and recording the EG as recovered EG.
3) Transferring the separating liquid obtained in the step 2) to a molecular distillation device, and controlling the residence time of the separating liquid on a heating surface to be 90 s at the temperature of 213 ℃ on the heating surface, the pressure to be 20 Pa and the temperature of 115 ℃ on a condensing surface, so that the mass ratio of distillate to residue can be stabilized at 7.2:2.8. The main component of the obtained residue is oligomer, which is marked as alcoholysis refined residue, collected and transferred into an alcoholysis device to participate in depolymerization reaction of the next production period; the distillate obtained was designated as monomer liquid, the BHET content of which was 98.4wt% and DEG content was 1.4wt%.
4) Uniformly mixing the monomer liquid obtained in the step 3) with a 1, 4-cyclohexanedimethanol dispersion liquid containing 500 ppm of ethylene glycol antimony and 600ppm of triphenyl phosphite at 170 ℃ according to the mass ratio of 95:5 under the protection of nitrogen at 175 ℃ and 101 kPa, transferring the mixture to a pre-polycondensation reaction kettle at the temperature of 253 ℃ for 2 hours, firstly keeping the pressure of 0.8 h at 101 kPa at the beginning, and then linearly reducing the pressure to 1 kPa along with the reaction time from 101 kPa; then transferring into a final polycondensation reaction kettle, cooling, granulating and drying the obtained melt at 280 ℃ and 30Pa for reaction 2h to obtain a basic slice with the intrinsic viscosity of 0.61 dL/g; the basic slice is transferred to a solid phase polycondensation reactor after being pre-crystallized and preheated to 210 ℃, reacts for 19 hours at 210 ℃, and after cooling, the bottle grade regenerated polyester slice is obtained, wherein the intrinsic viscosity is 0.853+/-0.009 dL/g, the melting point is 244.5+/-0.9 ℃, the hue L/b value is 82.5/1.14+/-0.06, and the acetaldehyde content is 0.42 mug/g.
Example 4
1) Uniformly mixing waste polyester material, EG, a catalyst, a stabilizer and active carbon according to a certain proportion, feeding the mixture to an alcoholysis device, carrying out depolymerization reaction for 3.5 h under the protection of inert gas and uniform stirring at the temperature of 195 ℃ and the pressure of 120kPa, filtering to remove active carbon and other filterable impurities at the temperature of 100 ℃, maintaining the filtrate at the temperature of 100 ℃, sequentially passing through cation exchange resin and anion exchange resin to carry out ion removal, wherein the total concentration of anions and cations in the obtained liquid is 26 ppm, and recording as alcoholysis liquid.
Wherein the waste polyester material is a colored cloth foam material with PET component content of 85.7wt%; the EG is polyester polymer grade EG and EG recovered in the step 2) according to a mixture of 1:0.5; the catalyst is tetraisopropyl titanate; the stabilizer is sodium acetate; the proportion is based on PET mass, EG addition amount is 300wt%, catalyst addition amount is 0.8wt%, and stabilizer addition amount is 4×10 -2 The weight percent of the active carbon is 5 weight percent.
2) And (3) preheating the alcoholysis solution obtained in the step (1) to 113 ℃ under the protection of inert gas, transferring the alcoholysis solution into a scraper type thin film evaporator with microwave radiation, and performing microwave radiation-induced thin film evaporation treatment to remove substances with boiling point lower than BHET in the alcoholysis solution, wherein the gap between a rotor scraper and the inner wall of the evaporator is 1 mm. In the treatment, the air pressure in the film evaporation cavity is controlled to be 250Pa through a vacuum system, the retention time of an alcoholysis liquid on an evaporation surface under the action of microwave irradiation is controlled to be 60 s through the feeding flow and the rotating speed of a scraping plate, the temperature of a finished liquid at a concentration outlet is controlled to be 161 ℃ through microwave power, the EG content in the concentrated finished liquid is 0.03wt%, the DEG content is 1.1wt%, and the concentrated finished liquid is recorded as a separating liquid; and condensing and collecting the low-boiling-point substances removed in the step, and transferring the low-boiling-point substances to a conventional rectifying and separating device to obtain EG with the purity of 99.0wt percent, which is recorded as recovered EG.
3) Transferring the separating liquid obtained in the step 2) to a molecular distillation device, and controlling the residence time of the separating liquid on a heating surface to be 95 s at the temperature of 214 ℃ on the heating surface, the pressure to be 20 Pa and the temperature of 113 ℃ on a condensing surface so as to stabilize the mass ratio of distillate to residue to be 7.3:2.7. The main component of the obtained residue is oligomer, which is marked as alcoholysis refined residue, collected and transferred into an alcoholysis device to participate in depolymerization reaction of the next production period; the distillate obtained was designated as monomer liquid, the BHET content of which was 98.2wt% and DEG content was 1.6wt%.
4) Uniformly mixing the monomer liquid obtained in the step 3) with a dispersion liquid of 1, 4-cyclohexanedimethanol containing 400 ppm of ethylene glycol titanium and 200ppm of trimethyl phosphate at 170 ℃ according to the mass ratio of 94:6, uniformly mixing at 175 ℃, under the protection of 101 kPa and nitrogen, maintaining the temperature, transferring to a pre-polycondensation reaction kettle, reacting at 255 ℃ for 1.8 hours, firstly maintaining the pressure of 1h at 101 kPa at the beginning, and then linearly reducing the pressure from 101 kPa to 1 kPa along with the reaction time; then transferring into a final polycondensation reaction kettle, cooling, granulating and drying the obtained melt at 275 ℃ under 25Pa and 2-h reaction, and obtaining a basic slice with the intrinsic viscosity of 0.60 dL/g; the basic slice is transferred into a solid phase polycondensation reactor after being pre-crystallized and preheated to 205 ℃, reacts for 21 hours at 205 ℃, and after cooling, the bottle grade regenerated polyester slice is obtained, wherein the intrinsic viscosity is 0.851+/-0.011 dL/g, the melting point is 243.9 +/-1.3 ℃, the hue L/b value is 84.1/1.01+/-0.05, and the acetaldehyde content is 0.56 mug/g.
Example 5
1) Uniformly mixing waste polyester material, EG, a catalyst, a stabilizer and active carbon according to a certain proportion, feeding the mixture to an alcoholysis device, carrying out depolymerization reaction for 4.5 h under the protection of inert gas and uniform stirring at the temperature of 192 ℃ and the pressure of 160kPa, filtering to remove the active carbon and other filterable impurities at the temperature of 85 ℃, maintaining the filtrate at the temperature of 85 ℃, sequentially passing through cation exchange resin and anion exchange resin to carry out ion removal, wherein the total concentration of anions and cations in the obtained liquid is 30 ppm, and recording as alcoholysis liquid.
Wherein the waste polyester material is a waste film compact material with PET component content of 90.1 wt%; the EG is polyester polymer grade EG and EG recovered in the step 2) according to a mixture of 1:0.5; the catalyst is zinc acetate; the stabilizer is sodium acetate; the proportion is based on PET mass, EG addition amount is 350wt%, catalyst addition amount is 1wt%, and stabilizer addition amount is 2×10 -2 The weight percent of the active carbon is 2 weight percent.
2) And (2) preheating the alcoholysis solution obtained in the step (1) to 118 ℃ under the protection of inert gas, transferring the alcoholysis solution into a scraper type thin film evaporator with microwave radiation, and performing microwave radiation-induced thin film evaporation treatment to remove substances with boiling point lower than BHET in the alcoholysis solution, wherein the gap between a rotor scraper and the inner wall of the evaporator is 1.5 mm. In the treatment, the air pressure in the film evaporation cavity is controlled to be 220Pa through a vacuum system, the retention time of an alcoholysis liquid on an evaporation surface under the action of microwave irradiation is controlled to be 75 s through the feeding flow and the rotating speed of a scraping plate, the temperature of a finished liquid at a concentration outlet is controlled to be 162 ℃ through microwave power, the EG content in the concentrated finished liquid is 0.02wt%, the DEG content is 1.1wt%, and the concentrated finished liquid is recorded as a separating liquid; and condensing and collecting the low-boiling-point substances removed in the step, and transferring the low-boiling-point substances to a conventional rectifying and separating device to obtain EG with the purity of 99.2wt%, and recording the EG as recovered EG.
3) Transferring the separating liquid obtained in the step 2) to a molecular distillation device, and controlling the residence time of the separating liquid on a heating surface to be 85 s at the temperature of 214 ℃ on the heating surface and the pressure to be 25 Pa on the condensing surface to be 115 ℃ so as to stabilize the mass ratio of distillate to residue to be 7:3. The main component of the obtained residue is oligomer, which is marked as alcoholysis refined residue, collected and transferred into an alcoholysis device to participate in depolymerization reaction of the next production period; the distillate obtained was designated as monomer liquid, the BHET content of which was 98.3wt% and DEG content was 1.5wt%.
4) Uniformly mixing the monomer liquid obtained in the step 3) with a dispersion liquid of 1, 4-cyclohexanedimethanol containing 400 ppm of germanium acetate and 600ppm of triphenyl phosphate at 170 ℃ according to the mass ratio of 96:4 under the protection of nitrogen at 175 ℃ and 101 kPa, transferring the mixture to a pre-polycondensation reaction kettle at the temperature of 252 ℃ for 2 hours, keeping the pressure of 0.8 h at 101 kPa at the beginning, and then linearly reducing the pressure to 1 kPa along with the reaction time from 101 kPa; then transferring into a final polycondensation reaction kettle, cooling, granulating and drying the obtained melt at 285 ℃ and 35Pa for reaction of 1.8 and h to obtain a basic slice with the intrinsic viscosity of 0.61 dL/g; the basic slice is transferred to a solid phase polycondensation reactor after being pre-crystallized and preheated to 210 ℃, reacts for 16 hours at 210 ℃, and after cooling, the bottle-grade regenerated polyester slice is obtained, wherein the intrinsic viscosity is 0.856+/-0.009 dL/g, the melting point is 245.9 +/-1.1 ℃, the hue L/b value is 83.5/0.95+/-0.06, and the acetaldehyde content is 0.45 mug/g.
Example 6
1) Uniformly mixing waste polyester material, EG, a catalyst, a stabilizer and active carbon according to a certain proportion, feeding the mixture to an alcoholysis device, carrying out depolymerization reaction for 4.5 h under the protection of inert gas and uniform stirring at the temperature of 192 ℃ and the pressure of 125kPa, filtering to remove the active carbon and other filterable impurities at the temperature of 85 ℃, maintaining the filtrate at the temperature of 85 ℃, sequentially passing through cation exchange resin and anion exchange resin to carry out ion removal, wherein the total concentration of anions and cations in the obtained liquid is 28 ppm, and recording as alcoholysis liquid.
Wherein the waste polyester material is waste polyester bottle flakes with the PET component content of 94.3 weight percent; the EG is polyester polymer grade EG and EG recovered in the step 2) according to a mixture of 1:0.5; the catalyst is tetra-n-butyl titanate; the stabilizer is potassium acetate; the proportion is based on PET mass, EG addition amount is 350wt%, catalyst addition amount is 1wt%, and stabilizer addition amount is 1×10 -2 The weight percent of the active carbon is 2 weight percent.
2) And (2) preheating the alcoholysis solution obtained in the step (1) to 118 ℃ under the protection of inert gas, transferring the alcoholysis solution into a scraper type thin film evaporator with microwave radiation, and performing microwave radiation-induced thin film evaporation treatment to remove substances with boiling point lower than BHET in the alcoholysis solution, wherein the gap between a rotor scraper and the inner wall of the evaporator is 1 mm. In the treatment, the air pressure in the film evaporation cavity is controlled to be 220Pa through a vacuum system, the retention time of an alcoholysis solution on an evaporation surface under the action of microwave irradiation is controlled to be 75 s through the feeding flow and the rotating speed of a scraping plate, the temperature of a finished solution at a concentration outlet is controlled to be 162 ℃ through microwave power, the EG content in the concentrated finished solution is 0.03wt%, the DEG content is 1.0wt%, and the concentrated finished solution is recorded as a separating solution; and condensing and collecting the low-boiling-point substances removed in the step, and transferring the low-boiling-point substances to a conventional rectifying and separating device to obtain EG with the purity of 99.2wt%, and recording the EG as recovered EG.
3) Transferring the separating liquid obtained in the step 2) to a molecular distillation device, and controlling the residence time of the separating liquid on a heating surface to 88 s at the temperature of 213 ℃ on the heating surface, the pressure to 23 Pa and the temperature of 115 ℃ on a condensing surface, so that the mass ratio of distillate to residue can be stabilized at 7.1:2.9. The main component of the obtained residue is oligomer, which is marked as alcoholysis refined residue, collected and transferred into an alcoholysis device to participate in depolymerization reaction of the next production period; the distillate obtained was designated as monomer liquid, the BHET content of which was 98.3wt% and DEG content was 1.4wt%.
4) Uniformly mixing the monomer liquid obtained in the step 3) with a 1, 4-cyclohexanedimethanol dispersion liquid containing 500 ppm of ethylene glycol titanium and 600ppm of triphenyl phosphite at 170 ℃ according to the mass ratio of 97:3, uniformly mixing at 175 ℃, under the protection of 101 kPa and nitrogen, maintaining the temperature, transferring to a pre-polycondensation reaction kettle, reacting at 250 ℃ for 2.2h, firstly maintaining the pressure of 0.8 h at 101 kPa at the beginning, and then linearly reducing the pressure to 1 kPa from 101 kPa along with the reaction time; then transferring into a final polycondensation reaction kettle, cooling, granulating and drying the obtained melt at 285 ℃ and 35Pa for reaction of 1.8 and h to obtain a basic slice with the intrinsic viscosity of 0.62 dL/g; the basic slice is transferred to a solid phase polycondensation reactor after being pre-crystallized and preheated to 215 ℃, reacts for 14 hours at 215 ℃, and after cooling, the bottle grade regenerated polyester slice is obtained, wherein the intrinsic viscosity is 0.854+/-0.007 dL/g, the melting point is 246.6+/-0.9 ℃, the hue L/b value is 82.9/0.89+/-0.06, and the acetaldehyde content is 0.38 mug/g.
The above description is merely a preferred embodiment of the present invention, and the above illustration is not to be construed as limiting the spirit of the present invention in any way, and any simple modification or variation of the above embodiments according to the technical spirit of the present invention, and equivalent embodiments that may be changed or modified to equivalent variations using the above disclosed technical spirit of the present invention, will still fall within the scope of the technical solutions of the present invention, without departing from the spirit and scope of the present invention.
Claims (5)
1. The preparation method of the bottle grade regenerated polyester chip is characterized by comprising the following steps:
1) Uniformly mixing waste polyester materials, EG, a catalyst, a stabilizer and active carbon according to a certain proportion, feeding the mixture to an alcoholysis device, uniformly stirring the mixture for depolymerization reaction for 2-5 hours under the protection of inert gas at the temperature of 185-200 ℃ and the pressure of 100-200 kPa, filtering the mixture at the temperature of 60-100 ℃ to remove the active carbon and other filterable impurities, maintaining the filtrate at the temperature of 60-100 ℃, sequentially flowing through cation exchange resin and anion exchange resin for ion removal and subtraction until the total concentration of anions and cations is less than or equal to 50 ppm, and recording the obtained liquid as alcoholysis liquid;
2) Preheating the alcoholysis solution obtained in the step 1) to 110-120 ℃ under the protection of inert gas, transferring the alcoholysis solution into a scraper type thin film evaporator with microwave radiation, and performing microwave radiation-induced thin film evaporation treatment to remove substances with boiling point lower than BHET in the alcoholysis solution; controlling the air pressure in the thin film evaporation cavity to be 200-300 Pa through a vacuum system, controlling the residence time of the alcoholysis liquid on the evaporation surface under the action of microwave irradiation to be 20-100 s through the feeding flow and the scraper rotating speed, and controlling the temperature of the finished liquid at 160-165 ℃ through a microwave power control concentration outlet to obtain concentrated finished liquid with EG less than 0.1wt% and DEG content of 0.8-1.2 wt% as separating liquid; meanwhile, condensing and collecting the low-boiling-point substances removed in the step, transferring the low-boiling-point substances to a conventional rectification separation device, and obtaining EG with purity more than or equal to 99.0 and wt% by conventional rectification separation, wherein the EG is recorded as recovered EG;
3) Transferring the separating liquid obtained in the step 2) to a molecular distillation device, and maintaining the mass ratio of distillate to residue at 6.9:3.1-7.4:2.6 by controlling the residence time of the separating liquid on a heating surface at the temperature of 210-215 ℃ and the pressure of less than or equal to 25 Pa and the temperature of a condensing surface at 110-120 ℃; the main component of the obtained residue is oligomer, which is marked as alcoholysis refining residue, and the alcoholysis refining residue is collected and transferred to the alcoholysis device in the step 1) to participate in depolymerization reaction in the next production period; the distillate is recorded as monomer liquid, the BHET content of the monomer liquid is more than or equal to 98.0wt percent, and the DEG content is 1.3-1.7 wt percent;
4) Uniformly mixing the monomer liquid obtained in the step 3) with a 1, 4-cyclohexanedimethanol dispersion liquid containing a certain amount of catalyst and stabilizer at 170 ℃ according to a certain proportion under the protection of nitrogen at the temperature of 170-180 ℃ and the pressure of 101kPa, transferring the mixture to a pre-polycondensation reaction kettle at the temperature of 250-255 ℃ for 1.5-2.5 hours, keeping the pressure in the kettle at 101kPa at the beginning, keeping the pressure unchanged for 0.5-1 hour, and then linearly reducing the pressure to 1kPa from 101kPa along with the reaction time; then transferring the mixture into a final shrinkage reaction kettle, reacting for 1.5-2.0 h at the temperature of 270-290 ℃ and the pressure of 20-50 Pa, cooling, granulating and drying the obtained melt, and obtaining a basic slice with the intrinsic viscosity of 0.60-0.62 dL/g; and (3) the basic slice is subjected to pre-crystallization and preheating to the solid phase polycondensation reaction temperature, then is transferred to a solid phase polycondensation reactor, is reacted for 12-24 hours at the temperature of 200-220 ℃, and is cooled to finish the reaction, so that the bottle-grade regenerated polyester slice is obtained.
2. The preparation method of the bottle grade regenerated polyester chips, according to claim 1, is characterized in that the waste polyester material in the step 1) is a post-consumer polyester product or production waste with PET component content more than or equal to 85wt%, and the catalyst is one of sodium carbonate, zinc acetate, tetra-n-butyl titanate and tetra-isopropyl titanate; the stabilizer is one of sodium acetate and potassium acetate; the waste polyester material, EG, catalyst, stabilizer and active carbon are in a certain proportion, wherein the mass of PET contained in the waste polyester material is taken as a reference, the EG addition amount is 200-400 wt%, the catalyst addition amount is 0.5-1.5 wt%, and the stabilizer addition amount is 0.5-5 multiplied by 10 -2 The weight percentage of the active carbon is 1-5wt%.
3. The method for producing bottle grade recycled polyester chips according to claim 1, wherein the EG in step 1) is a mixture of polyester polymer grade EG and recycled EG obtained in step 2) of the present invention in a ratio of 1:0.1 to 1:1.
4. The method for producing bottle grade recycled polyester chips as defined in claim 1, wherein the contents of the respective substances in the 1, 4-cyclohexanedimethanol dispersion liquid of 170 ℃ containing a certain amount of catalyst and stabilizer in the step 4) are as follows: the catalyst is 100-1000 ppm, and the stabilizer is 200-1000 ppm; the mixing ratio of the monomer liquid to the 1, 4-cyclohexanedimethanol dispersion liquid at 170 ℃ is 93:7-98:2.
5. The method for producing bottle grade recycled polyester chips of claim 1, wherein the catalyst in step 4) is one of titanium glycol, antimony glycol or germanium acetate; the stabilizer is one of trimethyl phosphate, triphenyl phosphate or triphenyl phosphite.
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