CN116284710B - Method for preparing polyester chips by chemical recycling of waste polyester fibers - Google Patents
Method for preparing polyester chips by chemical recycling of waste polyester fibers Download PDFInfo
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- CN116284710B CN116284710B CN202310573612.9A CN202310573612A CN116284710B CN 116284710 B CN116284710 B CN 116284710B CN 202310573612 A CN202310573612 A CN 202310573612A CN 116284710 B CN116284710 B CN 116284710B
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- Prior art keywords
- polyester
- waste
- bhet
- heating
- cooling
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- 229920000728 polyester Polymers 0.000 title claims abstract description 160
- 239000002699 waste material Substances 0.000 title claims abstract description 68
- 238000000034 method Methods 0.000 title claims abstract description 38
- 239000000835 fiber Substances 0.000 title claims abstract description 27
- 238000004064 recycling Methods 0.000 title claims abstract description 23
- 239000000126 substance Substances 0.000 title claims abstract description 22
- 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 55
- 238000010438 heat treatment Methods 0.000 claims abstract description 41
- 239000007788 liquid Substances 0.000 claims abstract description 34
- 238000001816 cooling Methods 0.000 claims abstract description 32
- 238000006243 chemical reaction Methods 0.000 claims abstract description 28
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims abstract description 26
- 239000000463 material Substances 0.000 claims abstract description 25
- 238000001914 filtration Methods 0.000 claims abstract description 22
- 239000002904 solvent Substances 0.000 claims abstract description 20
- 239000000843 powder Substances 0.000 claims abstract description 17
- 238000001035 drying Methods 0.000 claims abstract description 11
- 239000003999 initiator Substances 0.000 claims abstract description 11
- 238000000859 sublimation Methods 0.000 claims abstract description 11
- 230000008022 sublimation Effects 0.000 claims abstract description 11
- 238000012691 depolymerization reaction Methods 0.000 claims abstract description 10
- 239000000178 monomer Substances 0.000 claims abstract description 9
- 239000002245 particle Substances 0.000 claims abstract description 9
- 238000002156 mixing Methods 0.000 claims abstract description 7
- 238000000926 separation method Methods 0.000 claims abstract description 7
- 230000000379 polymerizing effect Effects 0.000 claims abstract description 4
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 claims description 92
- DNIAPMSPPWPWGF-UHFFFAOYSA-N Propylene glycol Chemical compound CC(O)CO DNIAPMSPPWPWGF-UHFFFAOYSA-N 0.000 claims description 27
- QPFMBZIOSGYJDE-UHFFFAOYSA-N 1,1,2,2-tetrachloroethane Chemical compound ClC(Cl)C(Cl)Cl QPFMBZIOSGYJDE-UHFFFAOYSA-N 0.000 claims description 20
- CTQNGGLPUBDAKN-UHFFFAOYSA-N O-Xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 20
- VZGDMQKNWNREIO-UHFFFAOYSA-N tetrachloromethane Chemical compound ClC(Cl)(Cl)Cl VZGDMQKNWNREIO-UHFFFAOYSA-N 0.000 claims description 18
- 239000003054 catalyst Substances 0.000 claims description 13
- QTBSBXVTEAMEQO-UHFFFAOYSA-N Acetic acid Chemical compound CC(O)=O QTBSBXVTEAMEQO-UHFFFAOYSA-N 0.000 claims description 12
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 claims description 12
- -1 nitrogen-containing compound Chemical class 0.000 claims description 12
- 229910001220 stainless steel Inorganic materials 0.000 claims description 11
- 239000010935 stainless steel Substances 0.000 claims description 11
- 238000002425 crystallisation Methods 0.000 claims description 10
- 230000008025 crystallization Effects 0.000 claims description 10
- YXFVVABEGXRONW-UHFFFAOYSA-N Toluene Chemical compound CC1=CC=CC=C1 YXFVVABEGXRONW-UHFFFAOYSA-N 0.000 claims description 9
- FJBFPHVGVWTDIP-UHFFFAOYSA-N dibromomethane Chemical compound BrCBr FJBFPHVGVWTDIP-UHFFFAOYSA-N 0.000 claims description 9
- ZWEHNKRNPOVVGH-UHFFFAOYSA-N 2-Butanone Chemical compound CCC(C)=O ZWEHNKRNPOVVGH-UHFFFAOYSA-N 0.000 claims description 8
- IAZDPXIOMUYVGZ-UHFFFAOYSA-N Dimethylsulphoxide Chemical compound CS(C)=O IAZDPXIOMUYVGZ-UHFFFAOYSA-N 0.000 claims description 8
- JUJWROOIHBZHMG-UHFFFAOYSA-N Pyridine Chemical compound C1=CC=NC=C1 JUJWROOIHBZHMG-UHFFFAOYSA-N 0.000 claims description 8
- DIKBFYAXUHHXCS-UHFFFAOYSA-N bromoform Chemical compound BrC(Br)Br DIKBFYAXUHHXCS-UHFFFAOYSA-N 0.000 claims description 8
- JHIVVAPYMSGYDF-UHFFFAOYSA-N cyclohexanone Chemical compound O=C1CCCCC1 JHIVVAPYMSGYDF-UHFFFAOYSA-N 0.000 claims description 8
- XBDQKXXYIPTUBI-UHFFFAOYSA-N dimethylselenoniopropionate Natural products CCC(O)=O XBDQKXXYIPTUBI-UHFFFAOYSA-N 0.000 claims description 8
- 238000001291 vacuum drying Methods 0.000 claims description 7
- FERIUCNNQQJTOY-UHFFFAOYSA-N Butyric acid Chemical compound CCCC(O)=O FERIUCNNQQJTOY-UHFFFAOYSA-N 0.000 claims description 6
- YNQLUTRBYVCPMQ-UHFFFAOYSA-N Ethylbenzene Chemical compound CCC1=CC=CC=C1 YNQLUTRBYVCPMQ-UHFFFAOYSA-N 0.000 claims description 6
- WSXIMVDZMNWNRF-UHFFFAOYSA-N antimony;ethane-1,2-diol Chemical group [Sb].OCCO WSXIMVDZMNWNRF-UHFFFAOYSA-N 0.000 claims description 6
- MVPPADPHJFYWMZ-UHFFFAOYSA-N chlorobenzene Chemical compound ClC1=CC=CC=C1 MVPPADPHJFYWMZ-UHFFFAOYSA-N 0.000 claims description 6
- BDAGIHXWWSANSR-UHFFFAOYSA-N methanoic acid Natural products OC=O BDAGIHXWWSANSR-UHFFFAOYSA-N 0.000 claims description 6
- 238000006068 polycondensation reaction Methods 0.000 claims description 6
- ZMXDDKWLCZADIW-UHFFFAOYSA-N N,N-Dimethylformamide Chemical compound CN(C)C=O ZMXDDKWLCZADIW-UHFFFAOYSA-N 0.000 claims description 5
- 150000002576 ketones Chemical class 0.000 claims description 5
- 229910052757 nitrogen Inorganic materials 0.000 claims description 5
- 150000007524 organic acids Chemical class 0.000 claims description 5
- PIICEJLVQHRZGT-UHFFFAOYSA-N Ethylenediamine Chemical compound NCCN PIICEJLVQHRZGT-UHFFFAOYSA-N 0.000 claims description 4
- FXHOOIRPVKKKFG-UHFFFAOYSA-N N,N-Dimethylacetamide Chemical compound CN(C)C(C)=O FXHOOIRPVKKKFG-UHFFFAOYSA-N 0.000 claims description 4
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical compound CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 4
- 235000011054 acetic acid Nutrition 0.000 claims description 4
- QARVLSVVCXYDNA-UHFFFAOYSA-N bromobenzene Chemical compound BrC1=CC=CC=C1 QARVLSVVCXYDNA-UHFFFAOYSA-N 0.000 claims description 4
- 229950005228 bromoform Drugs 0.000 claims description 4
- 235000019260 propionic acid Nutrition 0.000 claims description 4
- UMJSCPRVCHMLSP-UHFFFAOYSA-N pyridine Natural products COC1=CC=CN=C1 UMJSCPRVCHMLSP-UHFFFAOYSA-N 0.000 claims description 4
- IUVKMZGDUIUOCP-BTNSXGMBSA-N quinbolone Chemical compound O([C@H]1CC[C@H]2[C@H]3[C@@H]([C@]4(C=CC(=O)C=C4CC3)C)CC[C@@]21C)C1=CCCC1 IUVKMZGDUIUOCP-BTNSXGMBSA-N 0.000 claims description 4
- 239000008096 xylene Substances 0.000 claims description 4
- UOCLXMDMGBRAIB-UHFFFAOYSA-N 1,1,1-trichloroethane Chemical compound CC(Cl)(Cl)Cl UOCLXMDMGBRAIB-UHFFFAOYSA-N 0.000 claims description 3
- SCYULBFZEHDVBN-UHFFFAOYSA-N 1,1-Dichloroethane Chemical compound CC(Cl)Cl SCYULBFZEHDVBN-UHFFFAOYSA-N 0.000 claims description 3
- APQIUTYORBAGEZ-UHFFFAOYSA-N 1,1-dibromoethane Chemical compound CC(Br)Br APQIUTYORBAGEZ-UHFFFAOYSA-N 0.000 claims description 3
- OSWFIVFLDKOXQC-UHFFFAOYSA-N 4-(3-methoxyphenyl)aniline Chemical compound COC1=CC=CC(C=2C=CC(N)=CC=2)=C1 OSWFIVFLDKOXQC-UHFFFAOYSA-N 0.000 claims description 3
- CYTYCFOTNPOANT-UHFFFAOYSA-N Perchloroethylene Chemical group ClC(Cl)=C(Cl)Cl CYTYCFOTNPOANT-UHFFFAOYSA-N 0.000 claims description 3
- XSTXAVWGXDQKEL-UHFFFAOYSA-N Trichloroethylene Chemical group ClC=C(Cl)Cl XSTXAVWGXDQKEL-UHFFFAOYSA-N 0.000 claims description 3
- 235000019253 formic acid Nutrition 0.000 claims description 3
- CATSNJVOTSVZJV-UHFFFAOYSA-N heptan-2-one Chemical compound CCCCCC(C)=O CATSNJVOTSVZJV-UHFFFAOYSA-N 0.000 claims description 3
- VHHHONWQHHHLTI-UHFFFAOYSA-N hexachloroethane Chemical compound ClC(Cl)(Cl)C(Cl)(Cl)Cl VHHHONWQHHHLTI-UHFFFAOYSA-N 0.000 claims description 3
- BNIXVQGCZULYKV-UHFFFAOYSA-N pentachloroethane Chemical compound ClC(Cl)C(Cl)(Cl)Cl BNIXVQGCZULYKV-UHFFFAOYSA-N 0.000 claims description 3
- 238000006116 polymerization reaction Methods 0.000 claims description 3
- 150000003839 salts Chemical class 0.000 claims description 3
- 229950011008 tetrachloroethylene Drugs 0.000 claims description 3
- UBOXGVDOUJQMTN-UHFFFAOYSA-N trichloroethylene Natural products ClCC(Cl)Cl UBOXGVDOUJQMTN-UHFFFAOYSA-N 0.000 claims description 3
- 150000003863 ammonium salts Chemical class 0.000 claims description 2
- 159000000007 calcium salts Chemical class 0.000 claims description 2
- 159000000003 magnesium salts Chemical class 0.000 claims description 2
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 claims description 2
- 235000005985 organic acids Nutrition 0.000 claims description 2
- XAEFZNCEHLXOMS-UHFFFAOYSA-M potassium benzoate Chemical compound [K+].[O-]C(=O)C1=CC=CC=C1 XAEFZNCEHLXOMS-UHFFFAOYSA-M 0.000 claims description 2
- 159000000000 sodium salts Chemical class 0.000 claims description 2
- 150000003751 zinc Chemical class 0.000 claims description 2
- 239000004744 fabric Substances 0.000 abstract description 32
- 238000005516 engineering process Methods 0.000 abstract description 5
- 239000000243 solution Substances 0.000 description 32
- 239000005020 polyethylene terephthalate Substances 0.000 description 21
- 229920004933 Terylene® Polymers 0.000 description 20
- 239000000049 pigment Substances 0.000 description 17
- 229920002334 Spandex Polymers 0.000 description 15
- 239000004759 spandex Substances 0.000 description 15
- 239000012535 impurity Substances 0.000 description 14
- 239000004033 plastic Substances 0.000 description 13
- 229920003023 plastic Polymers 0.000 description 13
- 239000004677 Nylon Substances 0.000 description 11
- 229920001778 nylon Polymers 0.000 description 11
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 description 10
- 238000007639 printing Methods 0.000 description 10
- 239000013078 crystal Substances 0.000 description 9
- 239000012046 mixed solvent Substances 0.000 description 8
- 238000006136 alcoholysis reaction Methods 0.000 description 5
- 238000005056 compaction Methods 0.000 description 5
- 238000004043 dyeing Methods 0.000 description 5
- 239000004615 ingredient Substances 0.000 description 5
- 238000003756 stirring Methods 0.000 description 5
- 239000004753 textile Substances 0.000 description 5
- 239000004408 titanium dioxide Substances 0.000 description 5
- 229920006052 Chinlon® Polymers 0.000 description 4
- 229910001385 heavy metal Inorganic materials 0.000 description 4
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 4
- 150000002500 ions Chemical class 0.000 description 4
- 239000006224 matting agent Substances 0.000 description 4
- 239000003960 organic solvent Substances 0.000 description 4
- 238000005191 phase separation Methods 0.000 description 4
- 239000004800 polyvinyl chloride Substances 0.000 description 4
- 238000004321 preservation Methods 0.000 description 4
- 230000009286 beneficial effect Effects 0.000 description 3
- 239000003292 glue Substances 0.000 description 3
- 239000000047 product Substances 0.000 description 3
- 239000007787 solid Substances 0.000 description 3
- 229920000742 Cotton Polymers 0.000 description 2
- KKEYFWRCBNTPAC-UHFFFAOYSA-N Terephthalic acid Chemical compound OC(=O)C1=CC=C(C(O)=O)C=C1 KKEYFWRCBNTPAC-UHFFFAOYSA-N 0.000 description 2
- 150000001335 aliphatic alkanes Chemical class 0.000 description 2
- WOZVHXUHUFLZGK-UHFFFAOYSA-N dimethyl terephthalate Chemical compound COC(=O)C1=CC=C(C(=O)OC)C=C1 WOZVHXUHUFLZGK-UHFFFAOYSA-N 0.000 description 2
- 229910001873 dinitrogen Inorganic materials 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000002349 favourable effect Effects 0.000 description 2
- 230000001788 irregular Effects 0.000 description 2
- 239000010985 leather Substances 0.000 description 2
- 239000000203 mixture Substances 0.000 description 2
- 238000000053 physical method Methods 0.000 description 2
- SCVFZCLFOSHCOH-UHFFFAOYSA-M potassium acetate Chemical compound [K+].CC([O-])=O SCVFZCLFOSHCOH-UHFFFAOYSA-M 0.000 description 2
- 238000007781 pre-processing Methods 0.000 description 2
- 239000002994 raw material Substances 0.000 description 2
- 238000011160 research Methods 0.000 description 2
- 229920001169 thermoplastic Polymers 0.000 description 2
- 239000004416 thermosoftening plastic Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- XRBXGZZMKCBTFP-UHFFFAOYSA-N 4-(2,2-dihydroxyethoxycarbonyl)benzoic acid Chemical compound OC(O)COC(=O)C1=CC=C(C(O)=O)C=C1 XRBXGZZMKCBTFP-UHFFFAOYSA-N 0.000 description 1
- USFZMSVCRYTOJT-UHFFFAOYSA-N Ammonium acetate Chemical compound N.CC(O)=O USFZMSVCRYTOJT-UHFFFAOYSA-N 0.000 description 1
- 239000005695 Ammonium acetate Substances 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- ZOIORXHNWRGPMV-UHFFFAOYSA-N acetic acid;zinc Chemical compound [Zn].CC(O)=O.CC(O)=O ZOIORXHNWRGPMV-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 229910052783 alkali metal Inorganic materials 0.000 description 1
- 150000001340 alkali metals Chemical class 0.000 description 1
- 235000019257 ammonium acetate Nutrition 0.000 description 1
- 229940043376 ammonium acetate Drugs 0.000 description 1
- 230000004888 barrier function Effects 0.000 description 1
- IOTVKDRBFCMSMM-UHFFFAOYSA-N bromobenzene ethane-1,2-diol Chemical compound BrC1=CC=CC=C1.C(CO)O IOTVKDRBFCMSMM-UHFFFAOYSA-N 0.000 description 1
- VSGNNIFQASZAOI-UHFFFAOYSA-L calcium acetate Chemical compound [Ca+2].CC([O-])=O.CC([O-])=O VSGNNIFQASZAOI-UHFFFAOYSA-L 0.000 description 1
- 239000001639 calcium acetate Substances 0.000 description 1
- 235000011092 calcium acetate Nutrition 0.000 description 1
- 229960005147 calcium acetate Drugs 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000000576 coating method Methods 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000005260 corrosion Methods 0.000 description 1
- 230000007797 corrosion Effects 0.000 description 1
- 239000007857 degradation product Substances 0.000 description 1
- 239000008157 edible vegetable oil Substances 0.000 description 1
- 230000032050 esterification Effects 0.000 description 1
- 238000005886 esterification reaction Methods 0.000 description 1
- 238000002474 experimental method Methods 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 238000009413 insulation Methods 0.000 description 1
- UEGPKNKPLBYCNK-UHFFFAOYSA-L magnesium acetate Chemical compound [Mg+2].CC([O-])=O.CC([O-])=O UEGPKNKPLBYCNK-UHFFFAOYSA-L 0.000 description 1
- 239000011654 magnesium acetate Substances 0.000 description 1
- 229940069446 magnesium acetate Drugs 0.000 description 1
- 235000011285 magnesium acetate Nutrition 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Chemical class 0.000 description 1
- 239000002184 metal Chemical class 0.000 description 1
- 229910021645 metal ion Inorganic materials 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 235000010755 mineral Nutrition 0.000 description 1
- 239000011259 mixed solution Substances 0.000 description 1
- 238000004806 packaging method and process Methods 0.000 description 1
- 238000012856 packing Methods 0.000 description 1
- 229920001225 polyester resin Polymers 0.000 description 1
- 239000004645 polyester resin Substances 0.000 description 1
- 229920000139 polyethylene terephthalate Polymers 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 239000004814 polyurethane Substances 0.000 description 1
- 229920002635 polyurethane Polymers 0.000 description 1
- 229920000915 polyvinyl chloride Polymers 0.000 description 1
- 235000011056 potassium acetate Nutrition 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 238000010926 purge Methods 0.000 description 1
- 238000011084 recovery Methods 0.000 description 1
- 230000001172 regenerating effect Effects 0.000 description 1
- 229920006395 saturated elastomer Polymers 0.000 description 1
- 229920006126 semicrystalline polymer Polymers 0.000 description 1
- 239000002689 soil Substances 0.000 description 1
- 238000009987 spinning Methods 0.000 description 1
- 230000002194 synthesizing effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
- 238000005809 transesterification reaction Methods 0.000 description 1
- 239000004246 zinc acetate 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
- C08G63/78—Preparation processes
-
- C—CHEMISTRY; METALLURGY
- C07—ORGANIC CHEMISTRY
- C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07C67/00—Preparation of carboxylic acid esters
- C07C67/03—Preparation of carboxylic acid esters by reacting an ester group with a hydroxy group
-
- 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
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J11/00—Recovery or working-up of waste materials
- C08J11/04—Recovery or working-up of waste materials of polymers
- C08J11/10—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation
- C08J11/18—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material
- C08J11/22—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material by treatment with organic oxygen-containing compounds
- C08J11/24—Recovery or working-up of waste materials of polymers by chemically breaking down the molecular chains of polymers or breaking of crosslinks, e.g. devulcanisation by treatment with organic material by treatment with organic oxygen-containing compounds containing hydroxyl groups
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
- C08J2367/00—Characterised by the use of polyesters obtained by reactions forming a carboxylic ester link in the main chain; Derivatives of such polymers
- C08J2367/02—Polyesters derived from 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
Landscapes
- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
Abstract
The application belongs to the technical field of recycling of waste materials, and particularly relates to a method for preparing polyester chips by chemical recycling of waste polyester fibers, which is characterized by comprising the following steps: A. pretreating waste polyester fibers to obtain a polyester reclaimed material; B. mixing the polyester reclaimed material with an initiator, dihydric alcohol and an alkane-like solvent, and heating and pressurizing to carry out depolymerization reaction to obtain a polyester depolymerization solution; C. cooling and filtering the polyester depolymerization liquid, cooling and crystallizing, and carrying out solid-liquid separation to obtain polyester monomer BHET particles; D. drying the polyester monomer BHET particles, and performing sublimation desublimation to obtain BHET powder; E. and polymerizing the BHET powder to obtain the colorless transparent polyester chip. The application solves the problems that the recycling rate of the existing regenerated polyester technology is low, the reaction is incomplete, and the existing regenerated polyester technology cannot be applied to waste cloth.
Description
Technical Field
The application belongs to the technical field of recycling of waste materials, and particularly relates to a method for preparing polyester chips by chemical recycling of waste polyester fibers.
Background
Polyethylene terephthalate (polyester for short) is a semi-crystalline polymer material, and is the most main variety of thermoplastic polyester, commonly called polyester resin. The catalyst is prepared by the steps of synthesizing dihydroxyethyl terephthalate by the transesterification of dimethyl terephthalate and glycol or the esterification of terephthalic acid and glycol, and then carrying out polycondensation reaction. Together with PBT, are collectively referred to as thermoplastic polyesters, or saturated polyesters. The method is mainly used in the fields of textiles and plastics. The polyester raw material characteristics for spinning and plastics are different: such as viscosity, molecular weight, crystallinity, transparency, etc., both of which have been used in parallel. With the wide application of polyester materials in the fields of textile and plastics, waste textiles and waste packaging bottles formed after consumption are more and more used polyester materials. In China, about 2600 tens of thousands of tons of waste textiles are produced each year. About 200 ten thousand tons of the produced 950 ten thousand tons of old polyester bottle materials are low-value and low-quality bottles, boxes, sheets, shells, barrels, printing waste films and the like with miscellaneous colors, abnormal intrinsic viscosity, low melting point and the like. Because of complex components and large characteristic difference, no advanced scientific method for realizing high-value recycling is available at present. Because of its irreducibility, it places a great burden on the environment. At present, some low-end utilization and resource waste are caused, and waste textiles (mainly polyester clothes, leftover materials and the like), low-value low-quality old polyesters and other waste materials such as mineral water bottles, edible oil bottles, waste printing films, packing belts and the like are utilized to prepare regenerated colorless transparent Polyester (PET) slices, but the components of the old polyester waste materials are complex, the impurity content is high, and the intrinsic viscosity difference is large (0.4-0.9 dl/g).
The conventional method for regenerating the polyester is a pure physical method for sorting, crushing, cleaning and dehydrating and drying the waste polyester, and obviously, the physical method cannot remove the inherent non-polyester components and cannot modulate the intrinsic viscosity. At present, the preparation of the partially regenerated polyester chips generally adopts a micro-alcoholysis method, namely, a very small amount of ethylene glycol is adopted to carry out alcoholysis on polyester waste, but the addition amount of the ethylene glycol has great influence on the alcoholysis of the polyester waste: micro-alcoholysis is carried out on the regenerated polyester by adding ethylene glycol (0.5%) in a trace amount, and the effects of filtering out large insoluble external impurities and fine adjustment of intrinsic viscosity can be only achieved; for the polyurethane, nylon, cotton, printing ink on the printing film, nylon in the middle of the gas barrier bottle, PVC mixed in the sheet, a glue film and other materials contained in the waste cloth cannot be utilized. After the pretreatment of adding dihydric alcohol which is several times of the raw materials, the waste Polyester (PET) plastic is completely depolymerized, filtered, crystallized, sublimated (impurities such as spandex, chinlon, cotton, PVC, glue, heavy metal ions and the like are thoroughly removed), esterified and polymerized in a mode of completely depolymerizing the dihydric alcohol and alkane mixed solvent, and the high-purity colorless transparent polyester chip can be prepared, so that the search of a proper depolymerization method has important significance for recycling the waste polyester.
The inventor researches recycling waste Polyester (PET) from 2000, and searches a large amount of literature data and tests for a plurality of times, and finds that the yield of the polymerization after the depolymerization by a chemical method is not high, the yield is difficult to reach 70%, the cost is too high, so that the recovery by the chemical method is not economical, the improvement of the yield becomes particularly important, and the yield is not high.
Disclosure of Invention
The application aims to solve the problems that the recycling rate of the existing regenerated polyester technology is low, the reaction is incomplete, and the existing regenerated polyester technology cannot be applied to waste cloth. In view of the above, the present application provides a method for preparing waste Polyester (PET) plastic, which makes the purity of polyester chips high and can prepare various high-quality polyester plastic products.
In order to solve the technical problems, the application adopts the following technical scheme:
a method for preparing polyester chips by chemical recycling of waste polyester fibers comprises the following steps:
A. pretreating waste polyester fibers to obtain a polyester reclaimed material;
B. mixing the polyester reclaimed material with an initiator, dihydric alcohol and an alkane-like solvent, and heating and pressurizing to carry out depolymerization reaction to obtain a polyester depolymerization solution;
C. cooling and filtering the polyester depolymerization liquid, cooling and crystallizing, and carrying out solid-liquid separation to obtain polyester monomer BHET particles;
D. drying the polyester monomer BHET particles, and performing sublimation desublimation to obtain BHET powder;
E. and polymerizing the BHET powder to obtain the colorless transparent polyester chip.
Through intensive research and repeated experiments, the application can remove attachments and spandex on the surface of Polyester (PET) waste, nylon, PVC, pigment, printing ink, gray soil and the like without damaging and losing the Polyester (PET) material through simple pretreatment, and secondly, the application prevents reverse reaction in the depolymerization process by mixing excessive alkane-like solvent in dihydric alcohol, and at high temperature, part of depolymerized BHET is continuously transferred into alkane-like solvent phase along with the progress of the reaction, the proportion of PET-oligomer/EG is reduced, and balance is transferred to depolymerization. An additional advantage of the alkane-like solvent is the ease of separation of excess EG and purity of the product, since most degradation products dissolve in the alkane-like solvent phase. The product was extracted with hot water and then crystallized to obtain mainly monomeric BHET, which showed that the yield reached 97% to complete the present application.
Preferably, in the step B, the addition amount of the initiator is 0.2-0.5wt% of the polyester reclaimed material, and the mass ratio of the total amount of the dihydric alcohol and the alkane-like solvent to the polyester reclaimed material is 2-8:1; the mass ratio of the dihydric alcohol to the alkane-like solvent is 1:3-5.
Preferably, in step a, the preprocessing includes: and (3) carrying out contact reaction on the waste polyester fibers and the pretreatment solution in a heating state to obtain the polyester reclaimed material.
Heating the mixed solution of the waste polyester fibers, the dihydric alcohol and the nitrogen-containing compound, contacting for a certain time, dissolving pigments, coatings, glue, spandex, chinlon and other dirt impurities on the surface of the waste polyester materials into the dihydric alcohol, cooling, and then carrying out solid-liquid separation to obtain wet waste Polyester (PET) plastics with clean and colorless surfaces. The glycol solution comprises spandex, chinlon, pigment and other dirt impurities, wherein the impurities comprise one or more of metal ions and dye pigments.
In the method for chemically recycling the waste Polyester (PET) plastic, firstly, the waste polyester material and the dihydric alcohol are heated to a certain time, pigment, spandex, chinlon and other dirt impurities on the surface of the waste polyester material are dissolved into the dihydric alcohol, and then the temperature is reduced, the solid and the liquid are separated, so that wet waste Polyester (PET) plastic with clean and colorless surface is obtained; mixing a small amount of initiator with dihydric alcohol and alkane solvent, heating and depolymerizing to obtain polyester depolymerization liquid, cooling, filtering, cooling and crystallizing, filtering to obtain polyester monomer BHET particles, drying, sublimating and sublimating the dried BHET by a sublimator to obtain high-purity BHET powder, heating the powder and polymerizing into colorless transparent polyester chips by a known method. The initiator is a well known initiator to those skilled in the art and may be selected from one or more of alkali metals and metal salts. The pretreatment is that waste Polyester (PET) plastic is in countercurrent contact with dihydric alcohol, organic acid ketone and nitrogen-containing compound solvent in a closed pipeline, wherein the dihydric alcohol is selected from ethylene glycol, propylene glycol and the like in a specific embodiment. The organic acid is formic acid, acetic acid, propionic acid and butyric acid, the ketone is butanone, heptanone and cyclohexanone, the nitrogen-containing compound is N-methylpyrrolidone, pyridine, ethylenediamine, dimethyl sulfoxide, N, N-dimethylformamide and N, N-dimethylacetamide, and the alkane-like solvent is a hydrocarbon-like organic solvent or a halogenated hydrocarbon-like organic solvent, more specifically, carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, pentachloroethane, hexachloroethane, tetrachloroethylene, dibromomethane, bromoform, dibromoethane, bromoform, toluene, ethylbenzene, xylene, chlorobenzene or trichloroethylene; in a specific embodiment, the depolymerization is selected from tetrachloroethane. The technical means of the depolymerization, the filtration and the cooling crystallization are well known to those skilled in the art, and the present application is not particularly limited. The mixed depolymerization liquid comprises a very small amount of polyester oligomer and impurities, wherein the impurities comprise one or more of heavy metal ions, and the impurities are impurities brought by the waste polyester material and can have adverse effects on recycling the polyester chips.
Preferably, in step a, the specific operation of the pretreatment is as follows: putting the waste polyester fibers into a pipeline, compacting, reserving small holes at the bottom of the pipeline, heating the pretreatment solution, injecting the heated pretreatment solution into the pipeline, and carrying out countercurrent contact reaction on the pretreatment solution and the waste polyester fibers to obtain the polyester reclaimed material.
Preferably, in the step A, the mass ratio of the waste polyester fibers to the pretreatment solution is 1:2-10; the heating state is 130-198 ℃; the pretreatment solution comprises one or more of dihydric alcohol, organic acids, ketones and nitrogen-containing compounds; the pipeline is a stainless steel pipe.
For reasons of reason, in an ideal case of a yield of 100%, 1kg of pure PET can be converted entirely into 1.32 kg of BHET. However, the temperature and the type of the pretreatment solution can cause corrosion to the polyester material to different degrees in the pretreatment process, so that even in the depolymerization process, the alkane-like solvent is used to drive the reaction to the forward direction as much as possible, and the actual yield cannot reach 100%. Nevertheless, the yield of the process of the application is much higher than that of the conventional depolymerization process by about 70% at maximum.
Preferably, in the step A, the mass ratio of the waste polyester fibers to the pretreatment solution is 1:3-5; the heating state is 140-195 ℃; the dihydric alcohol comprises one or more of ethylene glycol and propylene glycol; the organic acid comprises one or more of formic acid, acetic acid, propionic acid and butyric acid; the ketone comprises one or more of butanone, heptanone and cyclohexanone; the nitrogen-containing compound comprises one or more of N-methylpyrrolidone, pyridine, ethylenediamine, dimethyl sulfoxide, N-dimethylformamide and N, N-dimethylacetamide; the diameter of the stainless steel tube is 10cm.
Preferably, in the step B, the heating temperature is 150-260 ℃, and the pressurizing pressure is 2-6 kg/cm 2 The depolymerization reaction is carried out under the protection of nitrogen for 3 hours; in the step C, the temperature after cooling is 50-120 ℃; in step D, the drying includes vacuum drying; in step E, the specific polymerization operation includes: adding the BHET powder into a closed container, adding a catalyst, heating and pumpingAnd (5) vacuum, and then continuously heating to perform polycondensation reaction to obtain the colorless transparent polyester chip.
Preferably, in the step B, the heating temperature is 190-210 ℃; in the step C, the temperature after cooling is 60-80 ℃; in the step D, the drying temperature is 80 ℃; in the step E, the closed container is a reaction kettle, the catalyst is ethylene glycol antimony, the catalyst is heated to 220 ℃ and vacuumized to 50Pa, and the catalyst is continuously heated to 300 ℃ for polycondensation reaction.
Preferably, in the step B, the initiator comprises one or more of potassium salt, calcium salt, sodium salt, magnesium salt, zinc salt, ammonium salt and ferric salt, the dihydric alcohol comprises one or more of ethylene glycol and propylene glycol, and the alkane-like solvent comprises one or more of hydrocarbon-like organic solvent and halogenated hydrocarbon-like organic solvent; in the step C, the specific operation of cooling and filtering includes: cooling to 80deg.C, filtering with 60 mesh filter to obtain insoluble substances, cooling to 60deg.C, and filtering with 0.5 μm filter element; in step D, the sublimation and desublimation includes sublimation using a sublimator, desublimation using a sublimator.
Preferably, in step B, the alkane-like solvent comprises one or more of carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, pentachloroethane, hexachloroethane, tetrachloroethylene, dibromomethane, bromoform, dibromoethane, bromobenzene, toluene, ethylbenzene, xylene, chlorobenzene, or trichloroethylene; in the step C, the temperature of cooling crystallization is 4-6 ℃; in the step D, the sublimation and desublimation concrete operation comprises the following steps: and drying the polyester monomer BHET particles, heating to 190 ℃ in a sublimator, heating to a vacuum pressure of below 50pa and above 0.2pa, sublimating, and then sublimating in a sublimator to obtain the BHET powder.
Compared with the prior art, the implementation of the application has the following beneficial effects:
in view of the problems of low purity and low yield after alcoholysis of dihydric alcohol in the prior art, the application provides a method for removing heavy metal ions, pigments and impurities in depolymerization liquid by crystallization after pretreatment and depolymerization of waste Polyester (PET) plastic. Specifically, the embodiment of the application discloses a method for removing heavy metal ions, pigments and impurities in depolymerization liquid by sublimation by utilizing waste Polyester (PET) plastics through pretreatment, mixing and depolymerization by dihydric alcohol and alkane-like solvent and then crystallizing.
The depolymerization technology of the application can obtain the liquid of the small molecular unit of the polyester, is convenient for subsequent operations such as filtration, crystallization, sublimation and the like to remove internal non-polyester and impurities, is favorable for obtaining colorless transparent polyester chips with extremely high purity, and is favorable for improving the quality of regenerated polyester chips finally.
The application provides a method for recycling waste Polyester (PET) plastics, which comprises the steps of simply preprocessing waste polyester, mixing the waste polyester with glycol and an alkane-like solvent, and depolymerizing the waste polyester in the presence of an initiator.
Detailed Description
In order to make the objects, technical solutions and advantages of the present application more apparent, the present application will be described in detail with reference to the following specific examples, and the scope of the present application is not limited by the following examples.
Example 1
1kg of waste terylene colored cloth (containing 6% of spandex, 2% of nylon, 5% of pigment ingredients during cloth printing and dyeing and the like) is put into a section of stainless steel tube with the diameter of 10cm for compaction, small holes are reserved at two ends, 10 kg of pretreatment solution (ethylene glycol and N-methylpyrrolidone are mixed according to the mass ratio of 3:2) with the temperature of 195 ℃ is added on the stainless steel tube for countercurrent contact with the terylene colored cloth, pigment, spandex, nylon and the like on the surface of the terylene cloth flow out along with the hot pretreatment solution, the color of the pretreatment solution which starts to flow out is very deep, the color of the pretreatment solution which flows out later becomes lighter to colorless, the wet white terylene cloth is put into a pressure-resistant reaction kettle with the weight of 8 liters, 3 g of calcium acetate and 5.5 kg of mixed solvent of ethylene glycol xylene (the mass ratio of 1:4) are added, the depolymerization reaction is completed after the temperature is raised to 210 ℃ in a sealed way by nitrogen purge, the pressure is 3.4 kg, the thermal insulation stirring reaction is carried out for 3 hours, filtering the insoluble substances with 60 meshes to obtain a polyester micromolecule BHET depolymerization liquid, cooling the polyester micromolecule BHET depolymerization liquid to 60 ℃, filtering the liquid by a 0.5 micron filter element to remove insoluble substances such as titanium dioxide matting agent and the like in the cloth, wherein the ethylene glycol is mutually insoluble with the dimethylbenzene, the depolymerized polyester micromolecule BHET is easily dissolved in the dimethylbenzene in the depolymerization process, and the BHET is not involved in the reverse reaction after being dissolved in the dimethylbenzene, so that the problem of the reverse reaction in the single ethylene glycol depolymerization process is solved, the viscosity of the ethylene glycol is much higher than that of the dimethylbenzene and is not beneficial to the subsequent cooling crystallization, the ethylene glycol is heavier than that of the dimethylbenzene, the dimethylbenzene is on the liquid due to the incompatibility of the ethylene glycol and the dimethylbenzene, carrying out phase separation, cooling the rest single dimethylbenzene depolymerization liquid to about 5 ℃ in a crystallizer, solid-liquid separation to obtain pale yellow 3-8 mm long irregular transparent BHET crystals, vacuum drying at 80deg.C, heating the dried BHET crystals to 190 deg.C, vacuum pressure below 50Pa, 0.2Pa or above, collecting snow-white BHET powder 1.073kg in a sublimator, adding 1kg of BHET into a 3 liter reaction kettle, adding ethylene glycol antimony catalyst, heating to 220deg.C, removing ethylene glycol, vacuumizing to 50Pa, heating to 300 deg.C, and polycondensing for 2.5 hr to obtain colorless transparent polyester with viscosity of 0.71 dl/g.
Example 2
1kg of waste terylene colored cloth (containing 7% of spandex, 8% of nylon, 4% of pigment ingredients during cloth printing and dyeing and the like) is put into a section of stainless steel tube with the diameter of 10cm for compaction, small holes are reserved at two ends, 4 kg of pretreatment solution (ethylene glycol, acetic acid and ethylenediamine are mixed according to the mass ratio of 3:1:1) with the temperature of 170 ℃ is added to be in countercurrent contact with the terylene colored cloth, pigment, spandex, nylon and the like on the surface of the terylene cloth flow out along with the hot pretreatment solution, the color of the pretreatment solution which starts to flow out is very deep, the color of the pretreatment solution which flows out later becomes lighter to colorless, the wet white terylene cloth is put into a pressure-resistant reaction kettle with the weight of 8 liters, 3 g of zinc acetate and 5.5 kg of ethylene glycol tetrachloroethane (the mass ratio of 1:4) mixed solvent are added, the mixture is purged with nitrogen gas and heated to 196 ℃ in a sealed state, the pressure is 3.4 kg, the depolymerization reaction is completed after 3 hours of heat preservation and stirring, filtering the insoluble substances with 60 meshes to obtain a polyester small molecular BHET depolymerized liquid, cooling the polyester small molecular BHET depolymerized liquid to 60 ℃, filtering the liquid by a 0.5 micron filter element to remove insoluble substances such as titanium dioxide matting agent and the like in the cloth, wherein ethylene glycol is mutually insoluble with tetrachloroethane, the depolymerized polyester small molecular BHET is easily dissolved in the tetrachloroethane in the depolymerization process, and the BHET can not participate in the reverse reaction after being dissolved in the tetrachloroethane, so that the problem of the reverse reaction in the single ethylene glycol depolymerization process is solved, the viscosity of ethylene glycol is much higher than that of tetrachloroethane and is unfavorable for the subsequent cooling crystallization, the ethylene glycol is lighter than that of tetrachloroethane and is above, the phase separation is carried out, the rest single tetrachloroethane depolymerized liquid is cooled to about 5 ℃ in a crystallizer for crystallization, solid-liquid separation to obtain pale yellow 3-8 mm long irregular transparent BHET crystal, vacuum drying at 80deg.C, heating the dried BHET crystal to 190 deg.C, vacuum pressure below 50Pa, 0.2Pa or above, collecting snow-white BHET powder 1.042kg in the sublimator, adding BHET1kg into 3 liter reactor, adding ethylene glycol antimony catalyst, heating to 220 deg.C, vacuumizing to 50Pa, heating to 300 deg.C, and polycondensing for 2.5 hr to obtain colorless transparent polyester with viscosity of 0.70 dl/g.
Example 3
1kg of waste terylene colored cloth (containing 8% of spandex and 5% of pigment ingredients and the like in PCV leather 6% cloth printing and dyeing) is put into a section of stainless steel tube with the diameter of 10cm for compaction, small holes are reserved at two ends, 5 kg of pretreatment solution (ethylene glycol, butanone and pyridine are mixed according to the mass ratio of 8:1:1) with the temperature of 198 ℃ is added on the stainless steel tube for countercurrent contact with the terylene colored cloth, pigment, spandex, PVC leather and the like on the surface of the terylene cloth flow out along with the hot pretreatment solution, the color of the pretreatment solution which starts to flow out is very deep, the color of the pretreatment solution which flows out later becomes lighter and lighter, the wet white terylene cloth is put into a pressure-resistant reaction kettle of 8 liters after being dried, 3 g of magnesium acetate and 5.5 kg of mixed solvent of ethylene glycol bromobenzene (the mass ratio of 1:4) are added, the mixed solvent is purged by nitrogen gas and heated to 190 ℃ in a sealed state, the pressure is 3.4 kg, the depolymerization reaction is completed after the heat preservation and stirring reaction is carried out for 3 hours, cooling to 80deg.C, filtering with 60 mesh filter to obtain depolymerized liquid of small molecular weight BHET, cooling to 60deg.C, filtering with 0.5 micrometer filter core to remove insoluble substances such as titanium dioxide matting agent, phase separating, cooling to about 5deg.C, crystallizing, solid-liquid separating to obtain pale yellow 3-8 mm long crystal of BHET, vacuum drying at 80deg.C, heating to 190 deg.C under vacuum pressure of 50Pa or below and 0.2Pa, collecting snow-white BHET powder 1.037 kg in the sublimator, adding 1kg of BHET into 3 liter reactor, heating to 220deg.C, vacuumizing to 50Pa, continuously heating to 300 deg.C, polycondensing for 2.5 hr, a colorless transparent polyester having a viscosity of 0.683dl/g was obtained.
Example 4
1kg of waste terylene colored cloth (containing 6% of spandex, 2% of nylon, 6% of pigment ingredients during cloth printing and dyeing and the like) is put into a section of stainless steel tube with the diameter of 10cm for compaction, small holes are reserved at two ends, 2kg of pretreatment solution (propylene glycol, propionic acid and dimethyl sulfoxide are mixed according to the mass ratio of 1:1:1) at the temperature of 140 ℃ is added to be in countercurrent contact with the terylene colored cloth, pigment, spandex, nylon and the like on the surface of the terylene cloth flow out along with the hot pretreatment solution, the color of the pretreatment solution which starts to flow out is very deep, the color of the pretreatment solution which flows out later becomes lighter to be colorless, the wet white terylene cloth is put into a pressure-resistant reaction kettle with the weight of 8 liters, 2 g of ammonium acetate and 8 kg of mixed solvent of propylene glycol carbon tetrachloride (the mass ratio of 1:3) are added, the mixture is purged with nitrogen, the temperature is increased to 260 ℃ in a sealed manner, the pressure is 2kg, the depolymerization reaction is completed for 3 hours under the condition of heat preservation and stirring, the temperature is reduced to 80 ℃, the insoluble matters are filtered by 60 meshes to obtain a polyester micro-molecular BHET depolymerization liquid, the temperature of the polyester micro-molecular BHET depolymerization liquid is reduced to 60 ℃, insoluble matters such as titanium dioxide flatting agent and the like in cloth are removed by filtering through a 0.5 micron filter element, because propylene glycol and carbon tetrachloride are mutually insoluble, the depolymerized polyester micro-molecular BHET is easy to dissolve in carbon tetrachloride in the depolymerization process, the BHET can not participate in the reverse reaction after dissolving in the carbon tetrachloride, thus solving the problem of the reverse reaction in the depolymerization process of single dihydric alcohol, the viscosity of propylene glycol is much higher than that of the carbon tetrachloride and is unfavorable for the subsequent cooling crystallization, the propylene glycol is lighter than the carbon tetrachloride, thus carrying out phase separation, and the rest single carbon tetrachloride depolymerization liquid is cooled to about 5 ℃ in a crystallizer, crystallizing, separating solid and liquid to obtain pale yellow crystals with a length of 3-8 mm, vacuum drying at 80deg.C, heating the dried crystals to 190 deg.C, vacuum pressure below 50Pa and over 0.2Pa, collecting snow-white BHET powder 1.050kg in a sublimator, adding 1kg of BHET into a 3 liter reaction kettle, adding ethylene glycol antimony catalyst, heating to 220 deg.C, vacuumizing to 50Pa, heating to 300 deg.C, and polycondensing for 2.5 hr to obtain colorless transparent polyester with viscosity of 0.72 dl/g.
Example 5
1kg of waste terylene colored cloth (containing 7% of spandex, 4% of nylon, 4% of pigment ingredients during cloth printing and dyeing and the like) is put into a section of stainless steel tube with the diameter of 10cm for compaction, small holes are reserved at two ends, 10 kg of pretreatment solution (ethylene glycol, cyclohexanone and N, N-dimethylacetamide are mixed according to the mass ratio of 2:2:1) with the terylene colored cloth is in countercurrent contact, pigment, spandex, nylon and the like on the surface of the terylene cloth flow out along with the hot pretreatment solution, the color of the pretreatment solution which flows out is very deep, the color of the pretreatment solution which flows out is lighter and lighter until the color of the pretreatment solution which flows out later is more and more colorless, the wet white terylene cloth is put into a pressure-resistant reaction kettle with the diameter of 8 liters, 5 g of potassium acetate and 2kg of mixed solvent of ethylene glycol dibromomethane (the mass ratio of 1:5) are added, the mixed solvent is purged with nitrogen, the temperature is increased to 150 ℃ in a sealed manner, the pressure is 6kg, the depolymerization reaction is completed for 3 hours under the condition of heat preservation and stirring, the temperature is reduced to 80 ℃, the insoluble matters are filtered by 60 meshes to obtain a polyester micro-molecular BHET depolymerization liquid, the polyester micro-molecular BHET depolymerization liquid is cooled to 60 ℃, insoluble matters such as titanium dioxide matting agent and the like in cloth are removed by filtering through a 0.5 micron filter element, because ethylene glycol and dibromomethane are mutually insoluble, the depolymerized polyester micro-molecular BHET is easy to dissolve in the dibromomethane in the depolymerization process, the BHET can not participate in the reverse reaction after dissolving in the dibromomethane, thus solving the problem of the reverse reaction in the single ethylene glycol depolymerization process, the viscosity of the ethylene glycol is much higher than that of the dibromomethane and is not beneficial to the subsequent cooling crystallization, the ethylene glycol is lighter than that of the dibromomethane, the ethylene glycol is on the upper side, the phase separation is carried out, the rest single dibromomethane depolymerization liquid is cooled to about 5 ℃ in a crystallizer, crystallizing, separating solid and liquid to obtain pale yellow crystals with a length of 3-8 mm, vacuum drying at 80deg.C, heating the dried crystals to 190 deg.C, vacuum pressure below 50Pa and above 0.2Pa, collecting 1.051kg of white BHET powder in a sublimator, adding 1kg of BHET into a 3 liter reaction kettle, adding ethylene glycol antimony catalyst, heating to 220 deg.C, vacuumizing to 50Pa, and continuously heating to 300 deg.C for polycondensation for 2.5h to obtain colorless transparent polyester with a viscosity of 0.71 dl/g.
The foregoing disclosure is merely illustrative of the preferred embodiments of the present application and is not intended to limit the scope of the claims herein, as equivalent changes may be made in the claims herein without departing from the scope of the application.
Claims (8)
1. The method for preparing the polyester chips by chemical recycling of the waste polyester fibers is characterized by comprising the following steps of:
A. pretreating waste polyester fibers to obtain a polyester reclaimed material; the pretreatment is as follows: the waste polyester fiber and the pretreatment solution are contacted and reacted in a heating state to obtain the polyester reclaimed material;
B. mixing the polyester reclaimed material with an initiator, dihydric alcohol and an alkane-like solvent, and heating and pressurizing to carry out depolymerization reaction to obtain a polyester depolymerization solution;
C. cooling and filtering the polyester depolymerization liquid, cooling and crystallizing, and carrying out solid-liquid separation to obtain polyester monomer BHET particles;
D. drying the polyester monomer BHET particles, and performing sublimation desublimation to obtain BHET powder;
E. polymerizing the BHET powder to obtain colorless transparent polyester chips;
in the step A, the specific operation of the pretreatment is as follows: putting the waste polyester fibers into a pipeline, compacting, reserving small holes at the bottom of the pipeline, heating the pretreatment solution, injecting the heated pretreatment solution into the pipeline, and carrying out countercurrent contact reaction on the pretreatment solution and the waste polyester fibers to obtain the polyester reclaimed material; in the step B, the alkane-like solvent comprises one or more of carbon tetrachloride, dichloroethane, trichloroethane, tetrachloroethane, pentachloroethane, hexachloroethane, tetrachloroethylene, dibromomethane, bromoform, dibromoethane, bromobenzene, toluene, ethylbenzene, xylene, chlorobenzene or trichloroethylene.
2. The method for preparing polyester chips by chemical recycling of waste polyester fibers according to claim 1, wherein in the step B, the addition amount of the initiator is 0.2-0.5wt% of the polyester reclaimed material, the mass ratio of the total amount of the dihydric alcohol and the alkane-like solvent to the polyester reclaimed material is 2-8:1, and the mass ratio of the dihydric alcohol to the alkane-like solvent is 1:3-5.
3. The method for preparing polyester chips by chemical recycling of waste polyester fibers according to claim 1, wherein in the step A, the mass ratio of the waste polyester fibers to the pretreatment solution is 1:2-10; the heating state is 130-198 ℃; the pretreatment solution comprises one or more of dihydric alcohol, organic acids, ketones and nitrogen-containing compounds; the pipeline is a stainless steel pipe.
4. The method for preparing polyester chips by chemical recycling of waste polyester fibers according to claim 3, wherein in the step A, the mass ratio of the waste polyester fibers to the pretreatment solution is 1:3-5; the heating state is 140-195 ℃; the dihydric alcohol comprises one or more of ethylene glycol and propylene glycol; the organic acid comprises one or more of formic acid, acetic acid, propionic acid and butyric acid; the ketone comprises one or more of butanone, heptanone and cyclohexanone; the nitrogen-containing compound comprises one or more of N-methylpyrrolidone, pyridine, ethylenediamine, dimethyl sulfoxide, N-dimethylformamide and N, N-dimethylacetamide; the diameter of the stainless steel tube is 10cm.
5. The method for preparing polyester chips by chemical recycling of waste polyester fibers according to claim 1, wherein in the step B, the heating temperature is 150-260 ℃, and the pressurizing pressure is 2-6 kg/cm 2 The depolymerization reaction is carried out under the protection of nitrogen for 3 hours; in the step C, the temperature after cooling is 50-120 ℃; in step D, the drying includes vacuum drying; in step E, the specific polymerization operation includes: adding the BHET powder into a closed container, adding a catalyst, heating, vacuumizing, and continuing heating to perform polycondensation reaction to obtain the colorless transparent polyester chip.
6. The method for preparing polyester chips by chemical recycling of waste polyester fibers according to claim 5, wherein in the step B, the heating temperature is 190-210 ℃; in the step C, the temperature after cooling is 60-80 ℃; in the step D, the drying temperature is 80 ℃; in the step E, the closed container is a reaction kettle, the catalyst is ethylene glycol antimony, the catalyst is heated to 220 ℃ and vacuumized to 50Pa, and the catalyst is continuously heated to 300 ℃ for polycondensation reaction.
7. The method for preparing polyester chips by chemical recycling of waste polyester fibers according to claim 1, wherein in the step B, the initiator comprises one or more of potassium salt, calcium salt, sodium salt, magnesium salt, zinc salt, ammonium salt and ferric salt, and the dihydric alcohol comprises one or more of ethylene glycol and propylene glycol; in the step C, the specific operation of cooling and filtering includes: cooling to 80deg.C, filtering with 60 mesh filter to obtain insoluble substances, cooling to 60deg.C, and filtering with 0.5 μm filter element; in step D, the sublimation and desublimation includes sublimation using a sublimator, desublimation using a sublimator.
8. The method for preparing polyester chips by chemical recycling of waste polyester fibers according to claim 1, wherein in the step C, the temperature of cooling crystallization is 4-6 ℃; in the step D, the sublimation and desublimation concrete operation comprises the following steps: and drying the polyester monomer BHET particles, heating to 190 ℃ in a sublimator, heating to a vacuum pressure of below 50pa and above 0.2pa, sublimating, and then sublimating in a sublimator to obtain the BHET powder.
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| CN202310573612.9A CN116284710B (en) | 2023-05-22 | 2023-05-22 | Method for preparing polyester chips by chemical recycling of waste polyester fibers |
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