CN114015112B - PET waste recycling and regenerating method and polyester material prepared by same - Google Patents
PET waste recycling and regenerating method and polyester material prepared by same Download PDFInfo
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- CN114015112B CN114015112B CN202111223764.3A CN202111223764A CN114015112B CN 114015112 B CN114015112 B CN 114015112B CN 202111223764 A CN202111223764 A CN 202111223764A CN 114015112 B CN114015112 B CN 114015112B
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- 239000002699 waste material Substances 0.000 title claims abstract description 82
- 229920000728 polyester Polymers 0.000 title claims abstract description 58
- 238000000034 method Methods 0.000 title claims abstract description 54
- 239000000463 material Substances 0.000 title claims abstract description 43
- 238000004064 recycling Methods 0.000 title claims abstract description 34
- 230000001172 regenerating effect Effects 0.000 title claims abstract description 20
- 239000002904 solvent Substances 0.000 claims abstract description 48
- 150000002736 metal compounds Chemical class 0.000 claims abstract description 20
- 239000003463 adsorbent Substances 0.000 claims abstract description 16
- 239000012535 impurity Substances 0.000 claims abstract description 13
- 239000004033 plastic Substances 0.000 claims abstract description 13
- 229920003023 plastic Polymers 0.000 claims abstract description 13
- 238000004806 packaging method and process Methods 0.000 claims abstract description 12
- 238000011084 recovery Methods 0.000 claims abstract description 10
- 239000000843 powder Substances 0.000 claims description 37
- 238000001556 precipitation Methods 0.000 claims description 19
- 238000007711 solidification Methods 0.000 claims description 17
- 238000010438 heat treatment Methods 0.000 claims description 16
- 230000008023 solidification Effects 0.000 claims description 16
- OKKJLVBELUTLKV-UHFFFAOYSA-N Methanol Chemical compound OC OKKJLVBELUTLKV-UHFFFAOYSA-N 0.000 claims description 15
- 238000000605 extraction Methods 0.000 claims description 13
- 238000001914 filtration Methods 0.000 claims description 13
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 12
- 238000006243 chemical reaction Methods 0.000 claims description 12
- SECXISVLQFMRJM-UHFFFAOYSA-N N-Methylpyrrolidone Chemical group CN1CCCC1=O SECXISVLQFMRJM-UHFFFAOYSA-N 0.000 claims description 11
- 238000002156 mixing Methods 0.000 claims description 11
- 239000003960 organic solvent Substances 0.000 claims description 11
- CSCPPACGZOOCGX-UHFFFAOYSA-N Acetone Chemical compound CC(C)=O CSCPPACGZOOCGX-UHFFFAOYSA-N 0.000 claims description 10
- 238000001035 drying Methods 0.000 claims description 9
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 claims description 8
- 150000001335 aliphatic alkanes Chemical group 0.000 claims description 7
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 claims description 5
- UXVMQQNJUSDDNG-UHFFFAOYSA-L Calcium chloride Chemical compound [Cl-].[Cl-].[Ca+2] UXVMQQNJUSDDNG-UHFFFAOYSA-L 0.000 claims description 4
- 239000001110 calcium chloride Substances 0.000 claims description 4
- 229910001628 calcium chloride Inorganic materials 0.000 claims description 4
- GUJOJGAPFQRJSV-UHFFFAOYSA-N dialuminum;dioxosilane;oxygen(2-);hydrate Chemical compound O.[O-2].[O-2].[O-2].[Al+3].[Al+3].O=[Si]=O.O=[Si]=O.O=[Si]=O.O=[Si]=O GUJOJGAPFQRJSV-UHFFFAOYSA-N 0.000 claims description 4
- 229910052901 montmorillonite Inorganic materials 0.000 claims description 4
- 150000001875 compounds Chemical class 0.000 claims description 3
- 230000001376 precipitating effect Effects 0.000 claims description 3
- 239000002994 raw material Substances 0.000 claims description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 claims description 2
- 229960000892 attapulgite Drugs 0.000 claims description 2
- 239000000440 bentonite Substances 0.000 claims description 2
- 229910000278 bentonite Inorganic materials 0.000 claims description 2
- SVPXDRXYRYOSEX-UHFFFAOYSA-N bentoquatam Chemical compound O.O=[Si]=O.O=[Al]O[Al]=O SVPXDRXYRYOSEX-UHFFFAOYSA-N 0.000 claims description 2
- 229910052791 calcium Inorganic materials 0.000 claims description 2
- 239000011575 calcium Substances 0.000 claims description 2
- 229910001622 calcium bromide Inorganic materials 0.000 claims description 2
- WGEFECGEFUFIQW-UHFFFAOYSA-L calcium dibromide Chemical compound [Ca+2].[Br-].[Br-] WGEFECGEFUFIQW-UHFFFAOYSA-L 0.000 claims description 2
- 125000004432 carbon atom Chemical group C* 0.000 claims description 2
- 239000004927 clay Substances 0.000 claims description 2
- 229910052625 palygorskite Inorganic materials 0.000 claims description 2
- 239000004575 stone Substances 0.000 claims description 2
- 238000005406 washing Methods 0.000 claims description 2
- 239000000047 product Substances 0.000 abstract description 23
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 13
- 239000000945 filler Substances 0.000 abstract description 8
- 230000000694 effects Effects 0.000 abstract description 7
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 abstract description 5
- 238000005265 energy consumption Methods 0.000 abstract description 4
- 238000002955 isolation Methods 0.000 abstract description 4
- 238000011069 regeneration method Methods 0.000 abstract description 3
- 239000000284 extract Substances 0.000 abstract description 2
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- 230000000052 comparative effect Effects 0.000 description 23
- 230000008569 process Effects 0.000 description 11
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- VLKZOEOYAKHREP-UHFFFAOYSA-N n-Hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 9
- 239000000126 substance Substances 0.000 description 9
- 238000012360 testing method Methods 0.000 description 9
- 241000196324 Embryophyta Species 0.000 description 8
- 238000011282 treatment Methods 0.000 description 8
- LYCAIKOWRPUZTN-UHFFFAOYSA-N Ethylene glycol Chemical compound OCCO LYCAIKOWRPUZTN-UHFFFAOYSA-N 0.000 description 7
- 239000007789 gas Substances 0.000 description 7
- 238000002834 transmittance Methods 0.000 description 7
- RTZKZFJDLAIYFH-UHFFFAOYSA-N Diethyl ether Chemical compound CCOCC RTZKZFJDLAIYFH-UHFFFAOYSA-N 0.000 description 6
- 238000004090 dissolution Methods 0.000 description 6
- 239000012459 cleaning agent Substances 0.000 description 5
- 239000005995 Aluminium silicate Substances 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- OFBQJSOFQDEBGM-UHFFFAOYSA-N Pentane Chemical compound CCCCC OFBQJSOFQDEBGM-UHFFFAOYSA-N 0.000 description 4
- 235000012211 aluminium silicate Nutrition 0.000 description 4
- 229910052799 carbon Inorganic materials 0.000 description 4
- NLYAJNPCOHFWQQ-UHFFFAOYSA-N kaolin Chemical compound O.O.O=[Al]O[Si](=O)O[Si](=O)O[Al]=O NLYAJNPCOHFWQQ-UHFFFAOYSA-N 0.000 description 4
- 239000007788 liquid Substances 0.000 description 4
- LQNUZADURLCDLV-UHFFFAOYSA-N nitrobenzene Chemical compound [O-][N+](=O)C1=CC=CC=C1 LQNUZADURLCDLV-UHFFFAOYSA-N 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000000746 purification Methods 0.000 description 4
- BHPQYMZQTOCNFJ-UHFFFAOYSA-N Calcium cation Chemical compound [Ca+2] BHPQYMZQTOCNFJ-UHFFFAOYSA-N 0.000 description 3
- 235000013361 beverage Nutrition 0.000 description 3
- 229910001424 calcium ion Inorganic materials 0.000 description 3
- 230000015556 catabolic process Effects 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 238000002425 crystallisation Methods 0.000 description 3
- 230000008025 crystallization Effects 0.000 description 3
- 238000004042 decolorization Methods 0.000 description 3
- 238000006731 degradation reaction Methods 0.000 description 3
- 238000005469 granulation Methods 0.000 description 3
- 230000003179 granulation Effects 0.000 description 3
- 239000000178 monomer Substances 0.000 description 3
- 239000003208 petroleum Substances 0.000 description 3
- 229920000642 polymer Polymers 0.000 description 3
- 239000000758 substrate Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 238000004140 cleaning Methods 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000002131 composite material Substances 0.000 description 2
- 239000008367 deionised water Substances 0.000 description 2
- 229910021641 deionized water Inorganic materials 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
- 239000012467 final product Substances 0.000 description 2
- 238000007306 functionalization reaction Methods 0.000 description 2
- 239000008187 granular material Substances 0.000 description 2
- WGCNASOHLSPBMP-UHFFFAOYSA-N hydroxyacetaldehyde Natural products OCC=O WGCNASOHLSPBMP-UHFFFAOYSA-N 0.000 description 2
- 230000001771 impaired effect Effects 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 238000003756 stirring Methods 0.000 description 2
- 239000004753 textile Substances 0.000 description 2
- 102000004190 Enzymes Human genes 0.000 description 1
- 108090000790 Enzymes Proteins 0.000 description 1
- 241000218378 Magnolia Species 0.000 description 1
- 230000009471 action Effects 0.000 description 1
- 230000032683 aging Effects 0.000 description 1
- 238000006136 alcoholysis reaction Methods 0.000 description 1
- 239000003963 antioxidant agent Substances 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 235000014171 carbonated beverage Nutrition 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000003086 colorant Substances 0.000 description 1
- 238000010668 complexation reaction Methods 0.000 description 1
- 238000004132 cross linking Methods 0.000 description 1
- 230000007547 defect Effects 0.000 description 1
- 229920006351 engineering plastic Polymers 0.000 description 1
- 238000003912 environmental pollution Methods 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 239000005452 food preservative Substances 0.000 description 1
- 235000019249 food preservative Nutrition 0.000 description 1
- 235000020510 functional beverage Nutrition 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000011159 matrix material Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 231100000956 nontoxicity Toxicity 0.000 description 1
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- 230000009467 reduction Effects 0.000 description 1
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- 229920005989 resin Polymers 0.000 description 1
- 238000000926 separation method Methods 0.000 description 1
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Classifications
-
- 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
- C08J11/06—Recovery or working-up of waste materials of polymers without chemical reactions
- C08J11/08—Recovery or working-up of waste materials of polymers without chemical reactions using selective solvents for polymer components
-
- 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
- C08J11/06—Recovery or working-up of waste materials of polymers without chemical reactions
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/16—Halogen-containing compounds
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/28—Nitrogen-containing compounds
-
- 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
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/16—Halogen-containing compounds
- C08K2003/162—Calcium, strontium or barium halides, e.g. calcium, strontium or barium chloride
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08K—Use of inorganic or non-macromolecular organic substances as compounding ingredients
- C08K3/00—Use of inorganic substances as compounding ingredients
- C08K3/28—Nitrogen-containing compounds
- C08K2003/287—Calcium, strontium or barium nitrates
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2201/00—Properties
- C08L2201/10—Transparent films; Clear coatings; Transparent materials
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L2201/00—Properties
- C08L2201/14—Gas barrier composition
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/62—Plastics recycling; Rubber recycling
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- Chemical & Material Sciences (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Separation, Recovery Or Treatment Of Waste Materials Containing Plastics (AREA)
Abstract
The invention discloses a method for recycling and regenerating PET waste and a polyester material prepared by the method, and belongs to the field of plastic recycling. The recovery and regeneration method of PET waste material of the invention extracts the primarily treated PET waste material to remove small molecular impurities in the waste material, then heats and dissolves the waste material fully by using good solvent NMP, uses adsorbent to decolorize and purify, introduces metal compound to complex with PET carboxyl end, uses specific kind and temperature poor solvent to solidify and precipitate the solution, so that the obtained polyester material has higher crystallinity, and further improves the intrinsic gas isolation performance and high transparency without introducing filler, and simultaneously has good appearance effect and high transparency; the method has no high energy consumption step, uses few reagents, is safe and environment-friendly, and the obtained product has high application value and wide application field. The invention also discloses the polyester material prepared by the method and further discloses a plastic product for food packaging.
Description
Technical Field
The invention relates to the field of plastic recycling, in particular to a PET waste recycling and regenerating method and a polyester material prepared by the PET waste recycling and regenerating method.
Background
PET (dimethyl terephthalate) is an important engineering plastic with good mechanical properties, wear resistance, creep resistance, chemical resistance and the like, and is widely used in the fields of food packaging, fiber, film and the like, wherein a large market share is concentrated in the food packaging industry, and general mineral water, carbonated beverage and functional beverage bottles are manufactured by adopting the material because of no toxicity, no smell, low price and permeation resistance, so that the annual waste is huge, and serious environmental pollution is caused. Plastic recycling is the most important way to solve plastic pollution, and at present, in the field of plastic recycling, PET beverage bottle recycling is the product with the highest recycling rate, but a huge gap still exists in high-end PET reclaimed materials in the market; more importantly, the domestic high-end recycled PET industry is still in a starting stage, a recycling system is incomplete, a recycling process is extensive, most of recycled PET products are poor in quality and performance, the product performance is greatly attenuated, the functionalization level is low, and the method can only be applied to the field of low-value production, and the high-end recycled PET products are quite rare.
At present, two methods for recycling PET in China mainly exist: chemical depolymerization and mechanical recovery.
The chemical depolymerization method is that the PET is depolymerized under the action of heating and a catalyst to generate a low molecular weight product or synthetic monomer, and then can be used as the monomer to participate in the polyester synthesis again to obtain the regenerated PET with high purity and high performance. In the prior art disclosed in CN107459788A, polyester reclaimed materials and polyester oligomer melt are subjected to reactive melt blending, then ethylene glycol is added for mixing and alcoholysis reaction to obtain depolymerized melt, and then the depolymerized melt is subjected to filtration and purification and polycondensation to obtain regenerated polyester melt, and then the regenerated polyester melt is subjected to cooling and granulation to obtain regenerated polyester chips; the technical scheme of CN102532815A uses glycol to depolymerize waste polyester textile, and the depolymerized monomer is purified and then polymerized to obtain regenerated polyester; in the technical scheme of CN110734578A, waste polyester material is firstly foamed and granulated to obtain waste polyester granules with a micropore structure, other easily soluble impurities are removed by using a solvent, and then the waste polyester granules are subjected to glycol depolymerization and repolymerization to obtain the regenerated polyester. However, as described in the above prior art, the chemical depolymerization method is complicated in process, and requires a step such as high-temperature depolymerization or high-temperature melting in the process, which is energy-consuming and costly.
The mechanical recovery method is to obtain the regenerated PET by directly blending, melt blending, extruding granulation and other simple physical and mechanical treatments of waste PET materials, and the recovery process is generally simpler than the chemical depolymerization method, but the PET is generally degraded in the process of the scheme, contains more impurities and has poor performance, and can only be applied to recycling in low-value products. In order to realize functionalization of products prepared by the methods, for example, for PET materials with high barrier property requirements, one generally uses a modifier to compound or use a composite film layer in the preparation process, for example, CN105622974A covers a PET substrate film with a coating so as to realize high barrier and high transparency effects, however, the method has certain requirements on the shape of the substrate, and meanwhile, the possibility of falling off exists between the coating and the PET substrate, so that the application range is narrow; CN109467895a is obtained by adding PEN resin and modified filler to a PET material matrix, so that the prepared composite material has intrinsic high barrier property, but the product has low transparency, light grey color and poor appearance effect.
Disclosure of Invention
Based on the defects existing in the prior art, the invention aims to provide a PET waste recycling and regenerating method, which is different from the traditional chemical depolymerization method and the mechanical recycling method, and the PET waste is purified, recycled and regenerated by an extraction-dissolution-solidification precipitation method, so that high energy consumption steps such as high-temperature melting and the like are not required to be introduced, the recycling and regenerating cost is saved, and the degradation of PET polymer chains is avoided; introducing a metal compound to be complexed with the end carboxyl of the PET before the solidification and precipitation process, so that the crystallinity of the PET is obviously improved during solidification and precipitation, and further high gas barrier property is obtained; the gas barrier property of the recycled and regenerated product is not improved by introducing barrier filler, and the obtained product has good appearance performance and high transparency.
In order to achieve the above purpose, the invention adopts the following technical scheme:
a PET waste recycling and regenerating method comprises the following steps:
(1) Washing and drying PET waste, and then crushing to obtain waste powder A;
(2) Heating and extracting the waste powder A by using an organic solvent, and then filtering and drying to obtain waste powder B;
(3) Adding the waste powder B into a good solvent, heating to 60-120 ℃ for mixing and dissolving, introducing an adsorbent to adsorb impurities, and filtering to obtain a purified polyester solution C; the good solvent is N-methyl pyrrolidone (NMP);
(4) Adding a metal compound into the purified polyester solution C, and mixing and dissolving to obtain a modified polyester solution D; the metal compound is a soluble calcium-containing compound;
(5) Adding the modified polyester solution D into a poor solvent, performing solidification and precipitation reaction, and filtering and precipitating to obtain the polyester material; the poor solvent is alkane with 5-6 carbon atoms, and the temperature of the poor solvent in the solidification and precipitation reaction is 30-50 ℃.
Preferably, the metal compound includes at least one of calcium chloride, calcium nitrate, and calcium bromide.
In the recovery and regeneration method of PET waste, firstly, the primarily treated PET waste is extracted to remove small molecular impurities in the waste, then the waste is fully heated and dissolved by using a good solvent NMP (instead of depolymerization, the macromolecular chain structure of PET is reserved, and the molecular chain or chemical bond breakage of PET is not involved), insoluble impurities are removed by using an adsorbent (decolorization and purification), and then a metal compound is introduced, calcium ions in the metal compound can be connected with two carboxyl end groups in the PET through complexation, so that the interaction between PET macromolecular chains is stronger, and then a specific poor solvent alkane is used for carrying out solidification and precipitation treatment on the solution, so that the obtained polyester material has remarkable high crystallinity and further shows excellent gas isolation; the method has low application cost, and under the condition of no filler, the degradation micromolecules and impurities which partially affect the appearance in the raw materials are further removed through decolorization and purification, and the obtained product has good appearance and high transparency.
In addition, the poor solvent alkane must be selected to be liquid and have strong fluidity under processing conditions, and alkanes with high carbon number are often viscous and have poor fluidity; while alkanes with low carbon number are mostly gaseous, and the mixed polyester solution is difficult to infiltrate under the process conditions of the invention.
Preferably, the alkane is any one of hexane, pentane, petroleum ether (a mixture of pentane and hexane).
In addition, the inventor also discusses the parameters of the dissolution and solidification precipitation processes in the process of the method, when the waste powder is added into a good solvent for dissolution, the waste powder needs to be heated to a certain temperature, if the temperature is too low, the dissolution rate of the waste powder is low, the waste powder cannot be fully dissolved, the subsequent decolorization and purification cannot be well performed, and the recovery rate of PET waste is low; if the dissolution temperature is too high, however, the PET in the scrap powder undergoes degradation by aging during dissolution, resulting in a significant reduction in the appearance of the final product.
Preferably, the temperature of the poor solvent at the time of the solidification precipitation reaction is 40 to 45 ℃.
When the temperature of the poor solvent in solidification and precipitation directly influences the non-isothermal crystallization kinetics process in the PET precipitation process, the crystallization rate and the crystallinity of PET are further changed; when the temperature of the poor solvent is too high, the PET precipitation efficiency is low, the yield is low, and when the temperature is too low, the polymer is precipitated too fast, and the crystallization effect of the polymer is affected, so that the cost performance is optimal when the temperature is 40-45 ℃ in the range of 30-50 ℃ comprehensively considered.
Preferably, the PET waste material in the step (1) is cleaned by at least one of a zwitterionic cleaning agent, an alkaline cleaning agent and a biological enzyme cleaning agent.
Preferably, the vacuum degree in the drying process in the step (1) is less than or equal to 0.1kPa, the temperature is 45-70 ℃, and the time is 1-4 hours.
Preferably, the average particle diameter of the waste powder A after the crushing treatment in the step (1) is 10 to 300. Mu.m.
After the PET waste is processed into the powder with the preferable particle size, the processing efficiency can be improved in the subsequent extraction process, and simultaneously, small molecular impurities and insoluble substances in the waste can be removed more effectively.
More preferably, the crushing treatment is a cryogenic crushing treatment, and the temperature of the PET waste is between-50 ℃ and-78 ℃ in the crushing treatment.
Preferably, the organic solvent heating extraction in the step (2) is as follows: sequentially using methanol, acetone and cyclohexane as organic solvents to respectively carry out heating extraction on waste powder A, wherein the volume ratio of the mass of the waste powder A to the organic solvent added each time is 1g: (5-30) mL, the temperature is 70-100 ℃, and the time for heating and extracting each time by adding the organic solvent is 0.5-4 h.
Under the conditions, small molecular impurities in the materials can be fully extracted through the specific organic solvent, and meanwhile, the solvent is not wasted excessively or PET in the materials is degraded due to improper conditions.
Preferably, the ratio of the volume of the good solvent to the mass of the waste powder B in step (3) is (5-10) mL:1g, and the dissolution time is 0.5-4 h.
Preferably, the adsorbent comprises at least one of active carbon, bentonite, montmorillonite, activated clay, medical stone and attapulgite powder, and the mass ratio of the adsorbent to the waste powder B is 1: (3-40).
Under the conditions, PET in the extracted waste powder can be fully dissolved in a good solvent NMP, and impurities, such as antioxidants, colorants and the like, which exude or are insoluble, can be fully removed by the adsorbent, so that the purity is improved.
Preferably, the mass ratio of the volume of the purified polyester solution C of step (4) to the added metal compound is 1mL: (0.0025 to 0.005 g).
The calcium ions in the metal compound can be complexed with the carboxyl end groups of two PET to improve the binding force between PET molecular chains, however, insufficient addition can not effectively improve the crosslinking degree of PET, and excessive addition can affect the processability of the material.
Preferably, the volume ratio of the modified polyester solution D to the poor solvent in the step (5) is 1: (10-20).
The use of the poor solvent is the key of the solidification precipitation reaction, if the amount of the poor solvent is too small, PET in the polyester solution cannot be sufficiently precipitated, so that the yield of a final product is not high, and if the excessive poor solvent is adopted, the recovery of subsequent waste liquid and the separation difficulty of system precipitated solids are increased.
The invention also aims at providing the polyester material prepared by the PET waste recycling and regenerating method.
It is still another object of the present invention to provide a plastic product for food packaging, the raw material for producing the plastic product for food packaging comprising the polyester material of the present invention.
Preferably, the plastic product for food packaging comprises a food preservative plastic film, a food packaging bag and a beverage packaging bottle.
The PET waste recycling and regenerating method has the advantages that the polyester material prepared under the condition of no filler is introduced is high in performance and low in production energy consumption; the PET regenerated material has higher intrinsic barrier property and transparency, has good appearance effect, has wider application range compared with PET regenerated material prepared by the prior art, and is particularly suitable for preparing plastic products in the field of food packaging with higher requirements on appearance, transparency and isolation.
The invention has the beneficial effects that the invention provides a recovery and regeneration method of PET waste, the method extracts the primarily treated PET waste to remove small molecular impurities in the waste, then fully heats and dissolves the waste by using good solvent NMP, uses an adsorbent to decolorize and purify, introduces metal compounds, adopts a poor solvent with specific type and temperature to carry out solidification and precipitation treatment on the solution, so that the obtained polyester material has higher crystallinity, further improves the intrinsic gas isolation performance of the polyester material under the condition of not introducing filler, and has good appearance effect and high transparency; the method has no high energy consumption step, uses few reagents, is safe and environment-friendly, and the obtained product has high application value and wide application field. The invention also provides the polyester material prepared by the method and further provides a plastic product for food packaging.
Detailed Description
The present invention will be further described with reference to specific examples and comparative examples for better illustrating the objects, technical solutions and advantages of the present invention, and the object of the present invention is to be understood in detail, not to limit the present invention. All other embodiments, which can be made by those skilled in the art without the inventive effort, are intended to be within the scope of the present invention. The experimental reagents and instruments designed in the practice and comparative examples of the present invention are common reagents and instruments unless otherwise specified.
The reagents used in the examples and comparative examples of the present invention are shown below:
PET waste: the Hongyu textile technology Co., ltd, the beverage bottle sheet material reclaimed materials, the PET content is about 97-99%;
methanol: guangzhou chemical reagent plant, analytical grade;
acetone: guangzhou chemical reagent plant, analytical grade;
cyclohexane: guangzhou chemical reagent plant, analytical grade;
n-methylpyrrolidone (NMP): guangdong Weng Jiang chemical company, ind., analytically pure;
nitrobenzene: guangzhou chemical reagent plant, analytical grade;
adsorbent (activated carbon): 20-50 mesh Shanghai Miclin Biochemical technology Co., ltd;
adsorbent (montmorillonite): 200-300 mesh Shanghai Miclin Biochemical technology Co., ltd;
commercial PET regrind: guangzhou city Mingmbh, model PETBG80;
kaolin: kaolin is purchased from Shanghai Michelia Biochemical technology Co., ltd., 200-300 mesh.
N-hexane: guangzhou chemical reagent plant, analytical grade;
petroleum ether: guangzhou chemical reagent plant, industrial purity;
calcium nitrate: guangzhou chemical reagent plant, analytical grade;
calcium chloride: guangzhou chemical reagent plant, analytical grade.
Example 1
An embodiment of the method for recycling and regenerating PET waste and the polyester material prepared by the method comprises the following steps:
(1) Cleaning 100g of PET waste by using an alkaline cleaning agent, drying in a drying oven at 65 ℃ for 2 hours (the vacuum degree is less than or equal to 0.1 kPa), and then crushing (cooling by liquid nitrogen) at-50 ℃ to-78 ℃ by using a cryogenic crusher to obtain waste powder A with the average particle diameter of 200 mu m;
(2) Adding the waste powder A into a first-stage high-temperature autoclave, introducing 700mL of methanol, heating and stirring at 80 ℃ for 2h for extraction, and filtering; 700mL of acetone is introduced, heated and stirred at 90 ℃ for 2h of extraction and filtration; 1000mL of cyclohexane is introduced, heated and stirred at 100 ℃ for 3h for extraction and filtration; drying to obtain waste powder B;
(3) Transferring the waste powder B into a second-stage high-pressure reaction kettle, adding 800mL of good solvent NMP, heating to 80 ℃, mixing and stirring for 2 hours until the waste powder B is fully dissolved, introducing 5g of adsorbent activated carbon to adsorb impurities, transferring the adsorbent activated carbon into a filter for filtration, and obtaining purified polyester solution C;
(4) Adding 3.0g of calcium chloride into the purified polyester solution C, and mixing and dissolving to obtain 800mL of modified polyester solution D;
(5) And adding the modified polyester solution D into 8L of poor solvent n-hexane with the temperature of 40 ℃, maintaining the temperature of the poor solvent to perform solidification and precipitation reaction, and filtering and precipitating to obtain the polyester material.
Example 2
The difference between this example and example 1 is only that the temperature of the poor solvent at the time of the solidification precipitation reaction is 50 ℃.
Example 3
The difference between this example and example 1 is only that the temperature of the poor solvent at the time of the solidification precipitation reaction is 30 ℃.
Example 4
The only difference between this example and example 1 is that the metal compound is calcium nitrate.
Example 5
The present example differs from example 1 only in that the amount of the metal compound added is 3.6g.
Example 6
The present example differs from example 1 only in that the amount of the metal compound added is 2.0g.
Example 7
The present example differs from example 1 only in that the amount of the metal compound added is 4.0g.
Example 8
The difference between this example and example 1 is that the good solvent addition amount is 750mL; the adsorbent is 10g of montmorillonite, and the poor solvent is petroleum ether.
Example 9
The difference between this example and example 1 is that the amount of methanol added was 500mL, the extraction temperature was 80℃and the extraction time was 1.5h; the addition amount of the acetone is 500mL, the extraction temperature is 80 ℃, and the extraction time is 1.5h; the cyclohexane addition amount is 1000mL, the temperature is 120 ℃, and the extraction time is 3h; the addition amount of the good solvent is 1000mL, and the heating temperature of the waste powder B when the waste powder B is dissolved in the good solvent is 90 ℃; the adsorbent is 15g of active carbon.
Comparative example 1
The PET waste recycling and regenerating method comprises the following steps:
(1) Cleaning 100g of PET waste by using an alkaline cleaning agent, drying for 2 hours at 65 ℃ (the vacuum degree is less than or equal to 0.1 kPa), and then crushing (cooling by liquid nitrogen) at-50 ℃ to-78 ℃ by using a cryogenic crusher to obtain waste powder A with the average particle diameter of 500 mu m;
(2) Adding the waste powder A into a double-screw extruder, filtering and purifying by a filter screen, mixing with kaolin filler, and performing melt extrusion granulation to obtain the polyester material.
Comparative example 2
The difference between this comparative example and example 1 is only that the temperature of the poor solvent is 60 ℃.
Comparative example 3
The only difference between this comparative example and example 1 is that the process does not add a metal compound.
Comparative example 4
The difference between this comparative example and example 1 is only that the heating temperature at which the waste powder B of step (3) is dissolved in a good solvent is 150 ℃.
Comparative example 5
The present comparative example differs from example 1 only in that the heating temperature at which the waste powder B of step (3) is dissolved in a good solvent is 50 ℃.
Comparative example 6
The difference between this comparative example and example 1 is only that the good solvent NMP was replaced by nitrobenzene.
Comparative example 7
The polyester material used in this comparative example was a commercial PET regrind, and was not subjected to any treatment and subsequent testing.
Comparative example 8
The only difference between this comparative example and example 1 is that the poor solvent used was replaced with deionized water.
Effect example 1
To verify the performance of the polyester materials prepared by the PET waste recycling and regenerating method of the present invention, the polyester materials obtained in examples 1 to 5 and comparative examples 1 to 8 were subjected to performance test, and the test method is as follows:
gas barrier test: the test was conducted according to the JIS-K7126-1-2006 differential pressure method, and the product was prepared into 50mm by 50mm uniform-size sheets with a thickness of 0.5mm for CO of the test sample 2 Transmittance;
light transmittance test: test according to standard GB 2410-2008; wherein the greater the light transmittance value, the greater the sample transparency;
chroma b value test: according to standard GB/T17931-2003 test; wherein the lower the number, the better the appearance of the sample.
The test results are shown in Table 1.
TABLE 1
As can be seen from Table 1, the polyester material obtained by the PET waste recycling and regenerating method of the present invention has high gas barrier property, high transparency and good appearance, and each product CO 2 The transmittance is less than 50cm 3 The color b value is less than or equal to 1.5, the light transmittance is more than or equal to 80%, and the transparency is high and is far superior to the existing commercial similar PET reclaimed material product of comparative example 7. In contrast, the polyester material prepared in comparative example 1 uses kaolin as filler to improve the gas barrier properties of the product, however, CO 2 The transmittance still reaches 51cm 3 /(m 2.24h.0.1 MPa) and chromaticity b value as high as 4.6, light transmittance as low as 43%; compared with the embodiment 1, the technical schemes of the comparative examples 2-6 select technical parameters which are not in the protection scope of the invention, and the performances of the obtained polyester materials are far less than those of the embodiments 1-9; the poor solvent in comparative example 8 was replaced with deionized water, and the metal compound was dissolved in the poor solvent while the polyester material was precipitated during the reaction, resulting in impaired connectivity of calcium ions with the two terminal carboxyl groups in PET, and significantly impaired properties of the resulting polyester material.
Finally, it should be noted that the above embodiments are only for illustrating the technical solution of the present invention and not for limiting the scope of the present invention, and although the present invention has been described in detail with reference to the preferred embodiments, it should be understood by those skilled in the art that the technical solution of the present invention may be modified or substituted equally without departing from the spirit and scope of the technical solution of the present invention.
Claims (10)
1. The PET waste recycling and regenerating method is characterized by comprising the following steps:
(1) Washing and drying PET waste, and then crushing to obtain waste powder A;
(2) Heating and extracting the waste powder A by using an organic solvent, and then filtering and drying to obtain waste powder B;
(3) Adding the waste powder B into a good solvent, heating to 60-120 ℃ for mixing and dissolving, introducing an adsorbent to adsorb impurities, and filtering to obtain a purified polyester solution C; the good solvent is N-methyl pyrrolidone (NMP);
(4) Adding a metal compound into the purified polyester solution C, and mixing and dissolving to obtain a modified polyester solution D; the metal compound is a soluble calcium-containing compound;
(5) Adding the modified polyester solution D into a poor solvent, performing solidification and precipitation reaction, and filtering and precipitating to obtain the polyester material; the poor solvent is alkane with 5-6 carbon atoms, and the temperature of the poor solvent in the solidification and precipitation reaction is 30-50 ℃.
2. The PET waste recycling and regenerating method according to claim 1, wherein the metal compound is at least one of calcium chloride, calcium nitrate, and calcium bromide.
3. The method for recovering and recycling PET waste according to claim 1, wherein the temperature of the poor solvent at the time of solidification and precipitation reaction is 40 to 45 ℃.
4. The PET waste recycling and regenerating method according to claim 1, wherein the organic solvent heating extraction in step (2) is: sequentially using methanol, acetone and cyclohexane as organic solvents to respectively carry out heating extraction on waste powder A, wherein the volume ratio of the mass of the waste powder A to the organic solvent added each time is 1g: (5-30) mL, the temperature is 70-100 ℃, and the time for heating and extracting each time by adding the organic solvent is 0.5-4 h.
5. The PET scrap recovery and recycling method according to claim 1, wherein the ratio of the volume of the good solvent to the mass of the scrap powder B in the step (3) is (5 to 10) mL:1g.
6. The PET waste recycling and regenerating method according to claim 1, wherein the adsorbent is at least one of activated carbon, bentonite, montmorillonite, activated clay, medical stone and attapulgite powder, and the mass ratio of the adsorbent to the waste powder B is 1: (3-40).
7. The PET scrap recovery and recycling method according to claim 1, wherein the mass ratio of the volume of the purified polyester solution C of step (4) to the added metal compound is 1mL: (0.0025 to 0.005 g).
8. The PET waste recycling and regenerating method according to claim 1, wherein the volume ratio of the modified polyester solution D to the poor solvent in the step (5) is 1: (10-20).
9. A polyester material produced by the PET waste recycling and regenerating method according to any one of claims 1 to 8.
10. A plastic product for food packaging, characterized in that the raw material for producing the plastic product for food packaging comprises the polyester material according to claim 9.
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