Chemical Recycling for Polyester Wastes, and

Their Applications

Cheng Qian

General Manager

Yangzhou Zhicheng Chemical Technology Co., Ltd.

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8th China International Recycled Polyester Conference

Chemical Recycling for Polyester Wastes, and Their Applications

Yangzhou Zhicheng Chemical Technology Co., Ltd.

8th China International Recycled Polyester Conference

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8th China International Recycled Polyester Conference

1. Variety and quality of regular PET wastes

1.2. As for chemical recycling, one needs to evaluate the quality of raw materials from following aspects:

� Tenacity (residual I.V.)

�Quality evenness

� Cleanliness

�Chemical composition

Chemical recycling is used only when one or more of above aspects need modification.

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1. Variety and quality of regular PET wastes

1.3. Raw materials are ranked according to the quality requirement of the chemical recycling.

VPET oil-less waste fiber = PET flake

> PET popcorn made from waste fiber, lump and film

> PET popcorn made from waste fabric

> PET popcorn made from waste garment

1.4. Characters of raw materials for chemical recycling

Raw materials for chemical recycling are mostly mixtures of PET waste of mixed sources, of varying quality, of minor impurities and of varied thermal history.

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2. Chemical recycling technology

2.1. Advantages of chemical recycling

One or more quality issues of raw materials can be solved through chemical treatment. In addition, the chemical recycling can

� transform materials unable to use directly to end product;

�enhance materials of low-value end use to high-value;

� realize a thorough transformation from waste resources to primary raw materials or intermediates.

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2. Chemical recycling technology

2.2. Features and implementation approaches of chemical recycling technology

�Features：modify molecular structure through chemical reaction

� Approaches：one or more chemical recycling methods can be applied according to the characters of raw materials and the requirements for end products.

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2. Chemical recycling technology

2.3. Widely applied chemical recycling methods

�Melt-phase bulk polymerization

�Partial depolymerization and repolymerization

�Complete depolymerization

�SSP

�Molecular chain extension

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3. Proprietary technology - PET-CR recycling process

3.1. PET-CR, the proprietary technology of Zhicheng, is a chemical recycling process to improve homogenization and I.V.

�Invention patent：Chemical treatment process for recycling melt-polycondensated polymer waste

�Utility model patent: Facility for chemical recycling melt-polycondensated polymer waste

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3.2. Principles of PET-CR recycling process

Though controllable depolymerization technology, the polyester melt is partially depolymerized into short-chain oligomers. The depolymerized molecules are then repolymerized to give desired chain length. By means of reversible equilibrium reaction of polyester, the molecular chains from different PET resources transfer to similar-length chains and repolymerized to macromolecules according to collision transition probability. The final products have a better homogenization in terms of both composition and polymerization degree, which indicates a modification of intrinsic viscosity and melting point on a microstructure scale and an enhanced quality of the melt.

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3. Proprietary technology - PET-CR recycling process

3.3. Typical process diagram of PET-CR recycling process

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分选/粉碎/漂洗/浮选/清洗/干燥

干燥瓶片料

熔体质量在线控制

原料预处理 瓶片料干燥单元

杂质 水份/粉尘

螺杆挤出机系统

助剂添加

熔体初过滤系统 机械杂质

一体化反应系统

加热系统

有色片

有机杂质

凝聚粒子

熔体输送系统

控制系统

熔体终级过滤系统 熔体分配系统

助剂添加

纺丝箱体

助剂添加

冷凝去杂质系统 真空系统

impurity

Raw material pretreatment

Colored flake

Sorting/grinding/rinsing/sifting/washing/drying

Moisture/dust

Drying

additivesDried flake

ExtruderMelt filtrationMechanical impurity

Controlling system

Heating system

additives

Melt transporting system

Integrated reaction system

Organic impurity Online melt QC

additivesVacuum system

Ultimate filtration system

Melt distribution system

Spinning beam

3. Proprietary technology - PET-CR recycling process

Condense & decontamination

Coagulated particles

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3.3. Typical process diagram of PET-CR recycling process

PET-CR recycling process can be modified according to raw materials of varying quality, to achieve efficient production of varying recycled products to fit customers’ need.

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3. Proprietary technology - PET-CR recycling process

4. End products of PET-CR process

4.1. End products of PET-CR

Filament yarn：POY, FDY, colored yarn

Staple fiber：Cotton-type virgin-like, H-T & L-Efiber, 3-dimensional-crimped fiber, colored fiber

Spunbond nonwoven, monofilament (for zipper tape), strapping, non-food-contact sheet,

PET chips

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4. End products of PET-CR process

4.2. PET-CR

1）Depolymerization by adding EG

2) IV increase

3）Modify molecular weight distribution

4）Four steps of decontamination

5）Modify composition distribution

6）Process determined by raw material quality

7）Basic process for B2B

8）End use depend on the quality of raw materials

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4. End products of PET-CR process

4.3. PET-CR process’s characteristics

1）Modify chain structure and molecular weight distribution2）Remove most impurities in raw materials3）Control the impact of flake moisture fluctuation4）Control IV increase range and IV fluctuation range5）Depolymerization degree can be adjusted based on the qualities of raw material and end product. 6）Continuous direct-melt-spinning, high stability and low operation cost7）Enhance fiber quality, improve irregularity in tenacity and denier of fibers8）Eliminate disturbance among extruder, filtration, spinning.9）Lower quality requirement for raw material and lower feedstock cost.

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5. Application of PET-CR process

5.1. PET-CR application

�Over forty demonstrating lines

�Combined capacity of over 2,500 tons/day

�Market occupancy of over 90% in chemical recycling capacity

�As many as 12 applications including chemical fiber

�24 standard specifications of 3 series

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5. Application of PET-CR process

5.2. Engineering project series

�Series A: high homogenization & medium IV enhance

Mainly for producing POY and FDY, with over 30 production lines in operation

�Series B：medium homogenization & high IV enhance

Mainly for low IV products like staple fiber

�Series C：deep treatment for special RPET products

Mainly applied for ultra-high IV required end use, special raw materials or high standard of production stability.

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6. Development and outlook of chemical recycling technology

Based on the national circular economy strategy and technology innovation union roadmap of CCFA Recycled Polyester Committee, We plan to make further breakthrough in PET-CR technology in the future.

�Low-cost continuous recycling process without drying or the use of screw extruder

�Advanced treatment of blended polyester textiles: separation, decoloring and purification

�Enhance dyeability and properties for further processing as a regular VPET fiber substitute.

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Thank you

8th China International Recycled Polyester Conference