Converting recycled PET flakes into high-quality pellets presents significant processing challenges. Current industrial systems struggle to maintain consistent pellet morphology and intrinsic viscosity (IV) levels, with temperature variations during cooling leading to deformation rates of up to 15% and IV drops of 0.1-0.2 dL/g through each thermal cycle.

The fundamental challenge lies in balancing rapid throughput against the precise thermal control needed for uniform crystallization and molecular weight preservation.

This page brings together solutions from recent research—including temperature-controlled underwater cutting systems, specialized cooling sequences that combine water and air stages, and extrusion modifications that reduce thermal degradation. These and other approaches focus on producing pellets that meet virgin PET quality standards while maintaining economic viability at industrial scale.

1. Method for Producing Plastic Granules with Controlled Intrinsic Viscosity and Molecular Structure in Recycled PET

ALPLA WERKE ALWIN LEHNER GMBH & CO KG, 2024

A method for producing plastic granules suitable for producing extrusion blow molded hollow bodies of recycled PET with high impact toughness and high gloss, and an extrusion process to achieve it. The method involves adjusting the intrinsic viscosity and molecular structure of recycled PET (rPET) to match virgin PET (vPET) in drop test performance and glossiness. The rPET particles are prepared by crystallization in hot air or infrared heat to control branching and molecular structure. The adjusted rPET properties allow comparable drop heights and gloss in blow molded bottles compared to vPET. This allows recycled bottles with similar performance to virgin ones, which is important for sustainability and recyclability.

CN117881515A-patent-drawing

2. Pelletizer with Integrated Crushing, Melting, Extrusion, Cooling, Cutting, and Moisture Removal Mechanisms

PARK DONG MYEUNG, 2024

A pelletizer to recycle waste plastic into pellets that can be reused in molding processes. The device crushes the waste plastic, melts and extrudes it into wire, cools the wire, cuts it into pellets, and removes moisture. This allows recycling waste plastics into pellets that can be used in injection molding machines.

3. Compact Automated Plastic Pelletizing Machine with Integrated Melting Extrusion, Cooling, and Conveyance Mechanisms

WANG SHENG, 2024

A compact and automated plastic pelletizing machine for recycling plastic waste into pellets for further processing. The machine has a fixed housing with an integrated melting extrusion device, pulling cooling device, mechanical conveyance claw, and pellet collection box. The extrusion device melts and forms the plastic into a strip. The pulling cooling device brings the strip into a pool for cooling. The conveyance claw pulls the cooled strip towards the collection box. This integrated design allows efficient and automated pelletizing of recycled plastic with a compact footprint.

CN117584315A-patent-drawing

4. Plastic Pelletizing Equipment with Integrated Variable-Position Screening Assembly and Rotating Baffle System

ZHEJIANG INNET TEXTILE MANUFACTURING CO LTD, ZHEJIANG INNET TEXTILE MFG CO LTD, 2023

Continuous and efficient plastic pelletizing equipment to recycle waste plastics without needing secondary screening. The equipment has a pelletization chamber with a feed guide, cutting knives, and a screening assembly. Waste plastics are fed into the chamber and cut into pellets. The screening assembly moves left and right to separate pellets by size. Qualified pellets fall into a collection box while unqualified ones stay in the screening assembly. After pelletizing, the baffle assembly rotates to separate and discharge the qualified pellets. Any remaining unqualified pellets are discharged from the side and fed back in for further cutting.

5. Recycled Plastic Packer System with Digital Control and Specialized Modules for Uneven Property Management

RUSO INC, 2023

Recycled plastic raw material packer system optimized for recycled plastics with uneven properties compared to virgin plastics. The system uses digital control and specialized modules to improve packing efficiency and quality of recycled plastics. It has an input hopper with measurement, circulation, primary supply, and foreign matter removal modules. Digital control analyzes real-time measurement data to optimize supply and removal based on pellet properties. This reduces defects and improves packing uniformity compared to simple hoppers used for virgin plastics.

6. Plastic Waste Conversion Method with Melting, Extrusion, and Cooling for Pellet Formation

EO JIN CHEMICAL CO LTD, 2023

A plastic raw material conversion method to manufacture recycled pellets from waste plastic. The method involves melting, extruding, cooling, and cutting the waste plastic to form pellets. The extruded plastic is cooled in a bath, then cut into pellet size. This produces high quality recycled pellets with improved properties compared to direct reuse of waste plastic. The process also involves filtering toxic gases during melting/extrusion, replacing hot cooling water, and separating stuck plastic from hoppers.

KR102489674B1-patent-drawing

7. Waste Plastic Flake Crushing and Sorting System with Pre-Heating and Double-Sided Visual Inspection

FPA CO LTD, LG CHEM LTD, 2022

Waste plastic flake crushing and sorting system for recycled pellets production that reduces defects and increases economic feasibility. The system crushes waste plastic flakes into smaller flakes, then visually inspects and sorts them to separate out defective flakes. The good flakes are used for high-color products, while the defective flakes are used for black products. This prevents black spots, foreign substances, and color issues in the recycled pellets. The system heats the flakes before crushing to prevent dust. The sorting steps of flipping and double-sided inspection ensure thorough sorting.

KR102475350B1-patent-drawing

8. Recycling Machine with Integrated Crusher, Extrusion System, and Pelletizer for Unsorted Plastic Waste

STEER ENGINEERING PRIVATE LTD, 2022

Recycling unsorted plastic waste into useful material like pellets. The recycling machine has a housing, crusher, extrusion system, and pelletizer inside. The machine accepts unsorted plastic waste through the housing inlet. The crusher converts it into smaller pieces. The extrusion system further processes the crushed plastic into compounded material. The pelletizer then shapes the compounded plastic into pellets. The pellets are exited through the housing outlet. This allows recycling of unsorted plastic waste into usable pellets without sorting.

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9. Pelletizer with Integrated Debris Capture and Recycling System

PEARL HAI JINLING PLASTIC CO LTD, 2022

Pelletizer for producing modified plastics that is environmentally friendly and recycles waste. The pelletizer has features to capture and recycle debris generated during the pelletizing process. A waste pipe collects debris falling from the pelletizer surface. A recovery device inside the waste pipe has slides, blocks, and a collection box to guide debris into the box. A fan circulates air to filter out debris. This prevents small particles from escaping and contaminating the final pellets. The debris collection improves pellet quality and reduces environmental impact.

10. Plastic Particle Mixing and Processing Equipment with Multi-Component Feeding and Water Circulation Granulation Assembly

HUNAN CHUANGXIN SCIENCE AND TECH CO LTD, HUNAN CHUANGXIN SCIENCE AND TECHNOLOGY CO LTD, 2022

Equipment for mixing and processing plastic particles that improves the quality of mixed plastic granules and avoids pollution during pelletizing. The equipment has a mixing feeding device with multiple feeding components to uniformly distribute different types of waste plastics into the processing chamber. It also has a water circulation granulation assembly with a high-pressure cutter that pelletizes the mixed plastics. The water circulation pelletizing prevents pollution compared to traditional dicing methods.

11. Waste Plastic Pelletizing Device with Integrated Blade Protection and Moisture Removal System

HUNAN JIALI PLASTIC IND CO LTD, HUNAN JIALI PLASTIC INDUSTRY CO LTD, 2021

Waste plastic recycling pelletizing device that reduces damage to cutting blades when pelletizing recycled plastic. The device has a base, chassis, crusher, cooling tank, heating chamber, pusher, closing device, scrap slide, cutting assembly, lifting device, and fan. The waste plastic is crushed, heated, pushed into a chamber, closed, melted, pushed out, cut, cooled, and pelletized. This sequence avoids cutting the hot, solidified plastic and prevents blade damage. The lifting device removes moisture before pelletizing.

CN215319933U-patent-drawing

12. Automated Waste Plastic Recycling Device with Segmented Chambers and Integrated Exhaust System

ZHANGJIAGANG WUHE MACHINERY CO LTD, 2021

A waste plastic recycling and pelletizing production device that automates recycling and granulating of waste plastics while mitigating environmental and safety issues. The device has a multi-step process with separate chambers for cutting, melting, and pelletizing. It also has an exhaust system with heat recovery, gas treatment, and odor absorption to handle the waste plastic processing gases. This allows cleaner, safer, and more efficient plastic recycling compared to traditional methods.

CN215202953U-patent-drawing

13. Apparatus for Producing Recycled Plastic Pellets with Moving Pipe Agitator for Pre-Extrusion Homogenization

DONGJIN, 2021

Apparatus for making recycled plastic pellets with improved quality. The process involves sorting, pulverizing, stirring, extruding, cooling, and cutting waste plastic to form pellets. The stirring step with a moving pipe agitator helps mix and homogenize the pulverized waste plastic before extrusion. This improves pellet quality compared to directly extruding the pulverized plastic. The stirring also allows loading the extruder with agitated plastic instead of static powder, further aiding mixing.

14. Recycled Plastic Pelletizing Device with Integrated Dust Collection and Defective Pellet Segregation Features

GUANGDONG RHINO NEW MATERIAL TECH CO LTD, GUANGDONG RHINO NEW MATERIAL TECHNOLOGY CO LTD, 2021

A modified recycled plastic pelletizing device to reduce dust generation and improve environmental friendliness during plastic pelletizing. The device has features like a dust collector below the pelletizing chamber, a separate box for collecting defective pellets, and a discharge port to remove fines. This helps contain dust during pelletizing and prevent it from escaping into the processing area. The device also has a feeding hopper, pelletizing unit, and discharge port to separate the pelletizing and discharge steps. This reduces dust generation compared to continuous pelletizing.

CN214026564U-patent-drawing

15. Waste Plastic Pellet Machine with Rotating Inner Frame and Diffuser Fans for Clog Mitigation

FUZHOU XINGSHENG IND CO LTD, FUZHOU XINGSHENG INDUSTRIAL CO LTD, 2021

Waste plastic pellet machine with improved granulation efficiency and reduced material clogging. The machine has a body, pellet manufacturing device, feed port, movable reclaiming door, and fixed frame. The pellet manufacturing device has a rotating inner frame with blades and a transition frame. The inner frame rotates to feed plastic into the blades for granulation. The reclaiming door allows access to clear clogged areas. The fixed frame has diffuser fans to prevent material buildup. This design enables uniform granulation, reduces clogging, and facilitates cleaning compared to conventional machines.

16. Pelletizing Module with Closed Extrusion Shell and Integrated Granulation Blade for Plastic Recycling

CHONGQING WANCHONGSHAN INTELLIGENT TECH CO LTD, CHONGQING WANCHONGSHAN INTELLIGENT TECHNOLOGY CO LTD, 2021

Pelletizing module for plastic recycling granulation lines that allows efficient conversion of waste plastics into reusable pellets. The module has a closed extrusion shell, a top ring with a hollow gear groove, and a bottom plate with an extrusion hole. A granulation blade with multiple teeth is attached to the top ring and meshes with a pinion gear. Molten plastic is extruded through the bottom plate hole, cut into pellets by the blade, and discharged through the groove. This granulating module integrates melting, cutting, and discharge steps into a single unit for efficient recycling.

CN112809964A-patent-drawing

17. Recycled Plastic Pelletizing Device with Automated Bidirectional Feeding and Integrated Clamping Cutter

Zhejiang Dajin New Materials Technology Co., Ltd., ZHEJIANG DAJIN NEW MATERIAL TECHNOLOGY CO LTD, 2021

Recycled plastic pelletizing device with automated feeding to improve efficiency and reduce manual intervention when pelletizing recycled plastics. The device has a feeding mechanism that moves backward as the cutter lowers to feed more material. This allows continuous feeding without stopping between cuts. The cutter also clamps and fixes the plastic during cutting to prevent deviations. The feeding mechanism moves the plastic into the cutter, then resets and feeds more as the cutter rises. This automatic feeding eliminates the need for external power or manual feeding.

CN111002353B-patent-drawing

18. Waste Plastic Pelletizing and Molding Apparatus with Symmetrical Cutting Blades and Integrated Cleaning Mechanism

Weihai Xinwei Environmental Protection Technology Co., Ltd., WEIHAI XINWEI ENVIRONMENTAL PROTECTION TECHNOLOGY CO LTD, 2021

A waste plastic pelletizing and molding process that improves the efficiency and quality of recycling waste plastics compared to existing methods. The process uses a custom crushing device with features like a cleaning mechanism, symmetrical cutting blades, and a wiping unit to prevent plastic accumulation and improve crushing uniformity. The device has a support frame, guide frame, cleaning mechanism, cutting mechanism, and crushing mechanism. The cleaning mechanism cleans the cutting blades to prevent plastic buildup. The symmetrical cutting blades rotate together. The wiping unit removes plastic from the cutting area. This prevents material from sticking to the blades and ensures consistent cutting and crushing.

CN111590790B-patent-drawing

19. Plastic Granulation System with Agitation-Enhanced Melting and Partition Plate for Fragment Control

LIU HEHUA, 2020

Recycling and granulating plastic products in a more efficient and consistent manner to improve the quality of the recycled plastic pellets. The method involves using specialized equipment like a plastic particle production device that melts and condenses the plastic fragments. This improves melting efficiency by agitating the fragments in the melting box. It also prevents unmelted plastic from entering further processing by using a partition plate. The condensation step is optimized by cutting off the extruded plastic before it enters the water pipe to avoid forming strips that need rework.

CN111844509A-patent-drawing

20. Pelletizing Machine with Integrated Pulverizing Mechanism and Heating-Equipped Extrusion Cylinder

Yutai County Fenglu Renewable Resources Co., Ltd., YUTAI FENGLU RENEWABLE RESOURCES CO LTD, 2020

Pelletizing machine for recycling waste plastics that allows efficient and environmentally friendly recycling of waste plastics. The machine has a pelletizing box, feed port, and discharge port. The pelletizing box has brackets at the bottom connected to a fixed frame. A motor connects to the frame. The box has an extrusion cylinder with heating rings inside. The feed port connects to the cylinder. The motor, heating rings, and switch form a circuit. A pulverizing mechanism below the feed port grinds the plastic.

21. Pelletizer with Dual-Chute Discharge System and Vacuum-Assisted Fines Separation Mechanism

22. Water-Cooled Granulation Apparatus with Swing Motion and Scooping Mechanism for Pelletizing Waste Plastics

23. Automatic Polyester Chip Pelletizing Equipment with Integrated Extrusion, Cutting, and Cooling Systems

24. Recycling Process for Producing Recycled PET Granules via High Temperature Polycondensation and Contaminant Removal

25. Method for Producing Resin Pellets Using Controlled Strand Diameter, Speed, and Cooling Spacing

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