Difficulties Faced in PET Recycling

PET plastic bottles are high-value-added waste, with simple recycling methods and relatively mature technology. A comprehensive industry chain has been established both domestically and internationally. Compared to other plastics, PET bottles have a high recycling rate. EU member states, through the establishment of a deposit system, have achieved a recycling rate of around 90%. In 2017, the EU's overall recycling rate reached 58.2%, Japan's was over 92%, and China's PET beverage bottle recycling rate reached over 94%.

Although the technology and processes for recycling and reproducing PET plastic are highly mature, many recyclers report that the quality of their recycled PE products is poor and fails to meet market standards, resulting in losses. To improve this situation, what issues should recyclers pay attention to in their future work?

Let's take a look at the potential challenges encountered in PET bottle recycling.

1. PET Bottle Labels

Currently, 70% of labels on PET beverage bottles in China are made of PVC. PVC and PET have similar densities, making them difficult to separate using simple flotation methods during recycling. Furthermore, the presence of PVC not only seriously affects the quality of PET flakes but also produces toxic substances. During the PVC production process, unpolymerized single molecules of vinyl chloride may be produced. Furthermore, its plasticizers contain harmful substances. These substances are easily released when exposed to high temperatures and oils and can enter the human body through food.

2. Glue for Labels

Label adhesives can cause problems with subsequent handling. Currently, two types of adhesives are commonly used on the market: solvent-based and water-based. Solvent-based adhesives are widely used by manufacturers due to their low cost, but solvent-based adhesives often contain organic reagents that are difficult to clean, making recycling more challenging.

3. PET Plastic Oil Bottles

Oil bottles account for approximately 5%-10% of recycled plastic bottles, and approximately 3% of them retain residual oil after use. This category also includes condiment bottles such as soy sauce and vinegar bottles. Mixed recycling during recycling and reuse can easily lead to cross-contamination, and the wastewater treatment costs during the crushing and cleaning process are high. Whether using physical or chemical methods, oil bottle recycling faces various challenges.

4. PET Bottle Sealing Aluminum Film and Rubber Gaskets

The aluminum film and rubber gaskets used to seal PET bottles increase the difficulty of recycling PET bottles. PET bottles primarily consist of preforms, caps, and labels. PET bottles made of a single material, such as PP or PE, can be recycled through sorting. However, PET bottles with mixed impurities are more difficult to sort and can affect the quality of the plastic bottle flakes.

5. Additives in PET Bottles

Some companies add additives such as colorants to PET. PET is food-contact grade, and there are clear regulations regarding the type and amount of additives. Whether bottles currently produced with these additives meet food-contact standards is not yet clearly defined. This has a significant impact on PET bottle recycling and secondary production.

6. Colored PET Bottles

Although plastic bottle recyclers can use automatic sorting machines to sort out colored bottles, colored PET bottles affect recycling efficiency. Different colored PET bottles must be recycled separately. Otherwise, the value of the recycled product will be reduced and the quality of the secondary bottles will be affected.

7. PP and PE Bottle Caps

Currently, most bottle caps on the market are made of PE and PP. Because PE and PE have similar densities to water, they are difficult to separate automatically in water. Rinsing tanks are required for separation, increasing the recycling cost of PET bottles.

8. Blending and Modification of PET with Other Materials

Due to its inherent performance limitations, PET is generally not used to make packaging components such as caps, handles, accessories, and labels. However, it can be blended with other materials to achieve the desired performance. However, these mixed materials and additives are difficult to remove during the sorting stage, so recycling must first assess their impact on the recycled PET product. Sometimes, recycling is impossible and must be disposed of as waste.

9. PET Bottles Contain Impurities Such as Mud and Sand

PET plastic bottles are primarily divided into two categories: bottle bricks and loose bottles. Bottle bricks can be further divided into five-color bricks, three-color bricks, and single-color bricks. Three-color bricks are predominant on the market, combining various colors such as white, blue, and green bottles. These bottle bricks contain impurities such as mud, sand, oil, and paper scraps, as well as other waste materials. Excessive debris during the unpacking process can significantly reduce the quality of the finished product.

10. Imperfect PET Bottle Recycling

The quality of the final bottle flakes is affected by many factors, including potential issues during high-temperature washing, multiple rinses, dehydration and drying, and air separation and packaging. Multiple rinses are crucial for ensuring the highest degree of cleanliness in the finished product. However, to save equipment costs, some manufacturers may only perform one or two rinses. This often fails to achieve the desired effect when the bottle label is heavily coated with adhesive and contains a lot of detergent. Furthermore, the dehydration and drying process is crucial, with extremely stringent requirements, typically requiring moisture content to be controlled within 1-2%.