PET is widely used in beverage bottles, food containers, transparent packaging, sheet materials, and fiber applications. Because PET is lightweight, transparent, and easy to process, it is used in large quantities around the world.
At the same time, recycling used PET bottles, PET containers, thermoforming scrap, and defective products into reusable resources has become an important issue in the plastic recycling industry. In recent years, with the growing focus on ESG, circular economy, recycled material usage, and carbon reduction, PET recycling has become more than waste treatment. It is now an important production process for supplying stable recycled raw materials.
In PET recycling, collected PET material is crushed, washed, dried, extruded, and pelletized into rPET pellets. In this type of PET reprocessing, selecting the right pretreatment and pelletizing equipment based on material condition is essential. To produce stable, high-quality rPET pellets, several factors must be properly managed, including material purity, washing quality, moisture control, extrusion conditions, degassing performance, and pellet shape consistency.
This article explains the basics of PET recycling, the process from PET bottles to rPET pellets, common challenges in rPET pellet production, and key points for selecting PET recycling equipment.
What This Article Covers
This article explains:
- The basic concept and process of PET recycling
- How PET bottles are recycled into rPET pellets
- Key challenges in rPET pellet production, including moisture control, IV drop, yellowing, and contamination
- Important points when selecting PET recycling equipment
- GEORDING’s pelletizing equipment for PET recycling
- Why washing lines and pelletizing systems should be planned as one continuous process
What Is PET Recycling?
PET recycling is the process of reusing used PET bottles, PET sheets, PET containers, PET flakes, and in-house production scrap as recycled raw materials. Collected PET materials are processed through sorting, crushing, washing, drying, extrusion, and pelletizing to become rPET pellets or recycled flakes.
PET is a relatively recyclable material, but stable recycling quality still requires proper control of material contamination, foreign objects, moisture, and thermal history. Especially when producing rPET pellets, the washing and drying condition before extrusion directly affects the final pellet quality.
The purpose of PET recycling is not only to reduce plastic waste. If recycled pellets can be produced with stable quality, they can be reused in sheet extrusion, fiber production, packaging materials, molded products, industrial applications, and more.
PET Bottle Recycling Process: From PET Bottles to rPET Pellets
Recycling PET bottles into rPET pellets is not simply a matter of crushing and melting the bottles. To produce stable rPET pellets, the entire process must be managed as a continuous workflow, including collection, sorting, crushing, washing, dewatering and drying, extrusion, degassing, and pelletizing.
In PET reprocessing, material purity, moisture control, foreign object removal, and extrusion conditions are all important. Used PET bottles, in particular, can be processed into bottle-derived recycled plastic or rPET pellets through proper pretreatment and pelletizing.
| Process | Purpose | Key Points |
|---|---|---|
| Collection and Sorting | Collect PET material and remove other materials or foreign objects | PVC, metal, labels, caps, and colored materials |
| Crushing | Turn PET bottles or scrap into flakes | Particle size consistency, stable feeding, and washing efficiency |
| Washing | Remove dirt, labels, adhesive, sand, and oil residue | Prevent black specks, contamination, and screen clogging |
| Dewatering and Drying | Reduce moisture in PET flakes | Prevent bubbles, yellowing, IV drop, and unstable extrusion |
| Extrusion and Degassing | Melt PET and remove moisture or volatile substances | Temperature control, residence time, and degassing performance |
| Pelletizing | Process PET into uniform rPET pellets | Pellet shape, size, and appearance consistency |
Collection and Sorting
First, used PET bottles or PET materials are collected and sorted to remove other materials, metal, labels, caps, colored materials, and other contaminants as much as possible.
This step is critical for stabilizing rPET pellet quality. If PVC, PP, PE, metal pieces, paper labels, or other contaminants are mixed into the material, they may cause extrusion problems or reduce pellet quality.
The higher the purity of the raw material, the lower the washing and contamination-removal burden in later stages, which helps produce more stable recycled pellets.
Crushing
After sorting, PET materials are crushed into a size suitable for extrusion and pelletizing. Turning PET bottles or PET sheets into uniform flakes can improve washing and drying efficiency.
If the particle size after crushing is inconsistent, washing and drying may become uneven. It may also cause unstable feeding into the extruder, resulting in fluctuations in melting conditions or output.
For this reason, crushing design and particle size consistency are important pretreatment factors in PET recycling.
Washing
Crushed PET flakes may contain label fragments, adhesive, beverage residue, oil, sand, dust, and other foreign objects. These contaminants need to be removed through a washing process.
If washing is insufficient, black specks or contamination may appear in the rPET pellets, and screen changes in the extruder may become more frequent. Contamination can also affect the quality stability of the final product.
For PET bottle-based materials, labels, caps, adhesive, and beverage residue are usually key removal targets. PET sheet scrap or in-house production scrap may be relatively clean, but dust and foreign matter still need to be controlled.
For contaminated PET materials or other waste plastics, GEORDING’s Plastic Washing Line can be integrated as pretreatment equipment to improve the stability of downstream extrusion and pelletizing.
For more information about waste plastic washing, refer to the related article: What Is a Plastic Washing Line? Equipment and Washing/Dewatering Process for Waste Plastic.
Dewatering and Drying
PET is highly sensitive to moisture. If PET flakes enter the extrusion process with excessive residual moisture after washing, hydrolysis, property degradation, bubbling, yellowing, and unstable extrusion may occur.
Therefore, dewatering and drying are essential in PET recycling. After washing, most of the moisture should first be removed mechanically, and then drying equipment can be used to further reduce residual moisture if needed.
If the goal is to produce stable rPET pellet quality, moisture control becomes an important factor in equipment selection. Depending on material condition, GEORDING’s Single Screw Squeezing Drying Machine or Horizontal Centrifugal Dryer can be integrated into the pretreatment process.
Extrusion and Degassing
After drying, PET flakes are fed into the extruder for melting and mixing. PET is sensitive to thermal history, so extrusion temperature, residence time, screw design, and feeding stability must be carefully controlled.
Degassing performance during extrusion is also important. Proper removal of moisture and volatile substances from the material helps improve pellet quality stability.
If extrusion conditions are unstable, pellet color, shape, surface condition, and material properties may fluctuate.
Pelletizing
After extrusion, PET is cut into uniform rPET pellets through the pelletizing process. The more stable the pellet shape, the more stable downstream feeding and molding performance can be.
Different applications require different rPET pellet quality standards. Sheet, fiber, packaging, and molded product applications may each require specific pellet appearance, size, moisture level, contamination control, and material property stability.
What PET Materials Are Suitable for Recycling?
PET recycling can handle various types of raw materials, including:
- Used PET bottles
- PET flakes
- PET sheet scrap
- PET thermoforming scrap
- Defective PET containers
- In-house PET production scrap
- PET bottle bales
- Transparent PET packaging materials
However, not all PET materials can be processed under the same conditions. Material contamination, moisture level, foreign objects, color, thickness, shape, and thermal history can all affect the required pretreatment and equipment configuration.
For example, used PET bottles usually require more attention to washing and sorting. In-house PET scrap or defective products are often cleaner, so the washing burden may be lower, but feeding stability and extrusion conditions still need to be managed.
To stably convert bottle-derived recycled plastic into rPET pellets, it is important to manage the entire process from material sorting, washing, drying, extrusion, and pelletizing.
Common Challenges in rPET Pellet Production
Producing rPET pellets is not just about melting and cutting the material. Quality stability must also be managed. The following are common challenges in many PET recycling operations.
Moisture Control
PET is sensitive to moisture. If PET flakes are not properly dried before extrusion, hydrolysis may cause material property degradation. Moisture can also cause bubbles during extrusion, affecting pellet appearance and quality.
Therefore, dewatering and drying after washing, as well as moisture control before extrusion, are critical in PET recycling. If the material has high moisture content or includes film-type material, equipment such as the Single Screw Squeezing Drying Machine or Horizontal Centrifugal Dryer can be integrated into the pretreatment process to improve downstream extrusion stability.
IV Drop
IV is an important quality indicator for PET. It is related to molecular weight and viscosity characteristics and may be a key evaluation factor depending on the final application.
Excessive thermal history, residual moisture, and improper processing conditions during extrusion may lead to IV drop. To stabilize rPET pellet quality, both material condition and extrusion conditions must be properly managed.
Yellowing
PET may yellow due to heat, contamination, foreign objects, or excessive residence time. For applications that require transparency, yellowing is a significant quality issue.
To reduce the risk of yellowing, washing quality, drying condition, temperature control, and residence time inside the extruder must be carefully managed.
Contamination
If PET flakes contain label fragments, metal, sand, other resins, adhesive, or other contaminants, pellet quality may decrease. Contamination may also cause screen clogging in the extruder or poor pellet appearance.
Sorting, washing, and filtration must therefore be properly managed. For materials with higher contamination levels, GEORDING can provide washing line configurations such as the Crushing, Washing and Drying Whole Plant Facility for Plastic Film or the Crushing, Washing and Drying Whole Plant Facility for Plastic Scrap, depending on material characteristics.
Inconsistent Pellet Shape
If pellet shape is unstable, downstream feeding and molding stability may be affected. Stable extrusion, cooling, and cutting conditions help produce more uniform pellets.
What Equipment Is Needed for PET Recycling and Pelletizing?
To recycle PET into rPET pellets, multiple pieces of equipment may be required depending on the material condition. Common equipment includes:
- Crusher
- Washing equipment
- Dewatering equipment
- Drying equipment
- Extruder
- Degassing unit
- Cutting unit
- Pelletizing machine
- Cooling equipment
- Conveying equipment
If the raw material is used PET bottles, washing and foreign object removal are especially important. If the raw material is in-house PET scrap, stable feeding and extrusion condition control become more important.
PET may also present feeding instability depending on its flow properties or material shape. Therefore, stable feeding into the extruder and precise extrusion temperature control are important factors when selecting equipment.
GEORDING provides a range of plastic recycling and pelletizing machines that can be configured according to material condition, production requirements, and target pellet quality.
GEORDING’s Force Feeding Single Stage Spaghetti Cutting Recycling & Pelletizing Machine
GEORDING’s Force Feeding Single Stage Spaghetti Cutting Recycling & Pelletizing Machine is designed for recycling and pelletizing materials such as PET, PS, ABS, PC, and PMMA.
The force-feeding design helps feed material into the extruder more consistently, improving extrusion stability. For PET flakes or PET scrap, where material shape or feeding condition may cause unstable extrusion, stable feeding and extrusion control are especially important.
In PET recycling, moisture and volatile management are also critical. By combining venting, degassing performance, temperature control, and stable cutting, the system helps support stable rPET pellet quality.
GEORDING can design pelletizing lines based on material characteristics, production capacity, installation space, and downstream requirements, integrating extrusion, cooling, cutting, and conveying processes as needed.
For a more detailed explanation of how this equipment can be applied to PET bottle recycling, read From Waste Bottles to rPET Pellets: How GEORDING’s PET Bottle Recycling Machine Closes the Loop.
You can also review GEORDING’s plastic recycling projects to learn more about complete recycling lines and equipment applications.
What Materials Other Than PET Can Be Recycled?
Depending on material conditions, pelletizing equipment used for PET recycling may also process other plastic materials, such as:
- PS
- ABS
- PC
- PA
- PMMA
- Engineering plastics
- PET sheet scrap
- In-house production scrap
- Various transparent plastic materials
However, each material has different melting points, flow properties, drying requirements, thermal stability, and extrusion conditions. Whether the same equipment can process different materials should be evaluated based on the material condition and target pellet quality.
Before selecting equipment, it is recommended to confirm the material type, processing capacity, material shape, moisture content, and final pellet quality requirements.
Key Points When Choosing PET Recycling Equipment
When selecting PET recycling equipment, it is important not to evaluate only the pelletizing machine capacity. The entire line, from pretreatment to extrusion and pelletizing, should be considered as one system.
Is It Suitable for the Material Condition?
Used PET bottles, PET flakes, sheet scrap, and in-house production scrap require different equipment configurations. If the material is contaminated, pretreatment equipment such as a Plastic Washing Line becomes important. If the material is relatively clean, stable feeding and extrusion performance may be more important.
Can It Manage Moisture Properly?
PET is sensitive to moisture. The line should be able to manage dewatering after washing, drying, and moisture control before extrusion.
Is Temperature Control Stable?
PET quality may be affected by excessive thermal history. Stable and precise temperature control during extrusion is therefore important.
Does It Have Degassing Capability?
The ability to remove moisture and volatile substances properly affects rPET pellet quality stability, making degassing performance an important evaluation factor.
Is Pellet Shape Stable?
Recycled pellets affect downstream feeding and molding performance. Cutting stability, cooling conditions, and cutting precision should also be evaluated.
Can the Line Be Customized?
PET recycling material conditions vary from factory to factory. Equipment suppliers should be able to design the line based on material condition, production capacity, installation space, and final application requirements.
Relationship Between Washing Lines and Pelletizing Equipment in PET Recycling
rPET pellet production requires not only pelletizing equipment but also a reliable upstream washing line. This is especially important when processing used PET bottles or contaminated PET materials, because crushing, washing, dewatering, and drying quality directly affect downstream extrusion and pelletizing.
If washing is insufficient before pelletizing, contamination, screen clogging, and poor pellet appearance may occur. If residual moisture is too high, bubbling or quality degradation may occur during extrusion.
Therefore, in PET recycling, the washing line and pelletizing equipment should not be considered separately. Instead, the process from material feeding to rPET pellet production should be designed as one complete recycling line. For more details about washing lines, refer to What Is a Plastic Washing Line? Equipment and Washing/Dewatering Process for Waste Plastic.
FAQ
How are PET bottles turned into rPET pellets?
PET bottles are first collected and sorted, then crushed into flakes. The flakes are washed, dewatered, dried, and fed into an extruder. After melting, degassing, and cutting, they are processed into rPET pellets.
What equipment is needed for rPET pellet production?
rPET pellet production typically requires a crusher, washing equipment, dewatering equipment, drying equipment, extruder, degassing unit, pelletizing machine, cooling equipment, and conveying equipment. For contaminated PET materials, pretreatment equipment such as a Plastic Washing Line is also important.
Do PET flakes need to be dried before pelletizing?
Yes. PET is sensitive to moisture. If it is extruded without proper drying, bubbling, yellowing, and property degradation may occur. Depending on material condition, equipment such as the Single Screw Squeezing Drying Machine or Horizontal Centrifugal Dryer can be integrated into the pretreatment process.
How can IV drop be reduced in PET recycling?
To reduce IV drop, moisture control, proper drying, stable extrusion temperature, avoiding excessive thermal history, and sufficient degassing performance are important. Washing quality and contamination control also affect quality stability.
Can materials other than PET be processed with the same equipment?
Depending on material conditions and equipment specifications, materials such as PS, ABS, PC, PMMA, and other engineering plastics may also be processed. GEORDING’s Force Feeding Single Stage Spaghetti Cutting Recycling & Pelletizing Machine can support applications for PET bottles, PS, ABS, PC, and PMMA. However, different materials have different drying requirements, melting points, flow properties, and extrusion conditions, so processing conditions should be confirmed in advance.
Summary
PET recycling is an important process for turning used PET bottles and PET scrap into reusable resources. To produce stable rPET pellets, collection, sorting, crushing, washing, dewatering and drying, extrusion, degassing, and pelletizing must be managed as a continuous process.
Because PET is sensitive to moisture and thermal history, moisture control, temperature control, degassing performance, and feeding stability are all important. In addition to the pelletizing machine, the overall line design, including the Plastic Washing Line and drying equipment, affects final rPET pellet quality.
As a plastic recycling equipment manufacturer, GEORDING provides equipment planning for PET recycling, rPET pellet production, washing, drying, extrusion, and pelletizing based on actual material conditions.
If you are evaluating PET recycling equipment or an rPET pellet production line, please contact GEORDING. We can help plan a suitable recycling line based on your material condition, production capacity, installation space, and downstream requirements.