With the increasing demand for recycled plastics, PET flakes have emerged as an essential material for the packaging, textile, and bottling industries. However, not all PET flakes are the same when it comes to their quality. In order to provide the required performance, safety, and economy, one needs to understand the parameters to check before purchasing PET flakes.
What Are PET Flakes?
PET flakes are produced by recycling post-consumer PET bottles through sorting, washing, shredding, and drying processes. These flakes are used to manufacture rPET fibers, sheets, strapping, and food-grade packaging. The final product quality largely depends on the recycling process and raw material selection.
Why PET Flake Quality Matters
Poor quality PET flakes can result in:
- Lacks Mechanical Strength
- Processing difficulties in extrusion or injection molding
- Product defects and increased rejections
- Safety and Compliance Risks
because quality checking parameters are essential for preventing losses during production as well as ensuring the quality is maintained.
Key Quality Parameters to Check Before Buying PET Flakes
1. Intrinsic Viscosity (IV)
Intrinsic Viscosity-IV- shows the molecular weight of PET. The larger the value of IV, the stronger and more durable the material.
- Fiber-grade PET flakes: Lower IV
- Bottle-grade PET flakes, Higher IV
Make sure the IV fits your desired application.
2. Moisture Content
Excess moisture may promote hydrolytic degradation during processing.
- Ideal moisture ≤ 0.5%
- Low moisture provides good melt stability and strength to the product.
Always request moisture test reports from suppliers.
3. Contamination level
Contaminants reduce the quality of PET flakes and affect the performance of an end product. Common contaminants include:
- PVC
- Polyolefins (PP, PE)
- Labels, glue, and metals
High-quality PET flakes have contamination of less than 100 ppm.
4. Colour Consistency
PET flakes are normally categorized as:
- Clear / Super Clean
- Sky Blue
- Mixed Color
For food-grade and premium applications, clear flakes are preferred. The color inconsistency could affect the aesthetics and transparency in the final product.
5. Bulk Density
Bulk density informs material handling and feeding efficiency in the processing chain.
* Consistent bulk density = smooth extrusion.
* Low density may indicate fines or irregular flake size.
6. Flake Size & Shape
Uniform flake size improves:
- Melting consistency
- Washing efficiency
- Final product quality
Irregular flakes might cause processing upsets or nonuniform melting.
7. Ash Content
Ash content is a measure of the inorganic residue that results after burning PET flakes.
- Lower ash content = higher purity
- ideal ash content: ≤0.3%
High ash content normally indicates poor washing or contamination.
8. Degree of Acetaldehyde
In food and beverage packaging, it is very important to maintain low levels of acetaldehyde to avoid taste and odor problems.
- Lower AA assures adherence to food safety.
- Critical for the flakes in bottle-grade PET
9. Washing & Drying Quality
Well-washed PET flakes should be:
- Free from oil, glue, and label residues
- Results are properly dried to avoid moisture-related defects.
Ask suppliers to provide information on hot washing and drying processes.
Are PET Flakes Safe for Food-Grade Applications?
PET flakes can be employed for any food-contact use, provided they undergo approved recycling processes. One must check for certification and testing reports before purchasing food-grade PET flakes.
How to Choose the Right PET Flake Supplier
Before finalizing a purchase:
- Request for laboratory test reports.
- Check sample consistency
- Verify quality certifications
- Stabilize supply and make it traceable.
Trustworthy suppliers emphasize quality and document transparency.
Also Read: Textile-to-Textile Recycling: Closing the Loop in Polyester Fibres
Knowledge of quality parameters to check before buying PET flakes helps the buyer ensure performance, safety, and long-term cost savings. Be it IV, moisture content, contamination, or color consistency, each is an important contributor to final product quality.
Choosing among the right PET flakes isn’t all about price but also reliability, compliance, and consistent results.
