The primary function of hot washing is to vigorously remove various stubborn contaminants from PET bottle flakes (fragments) through high temperatures and chemical agents, thereby obtaining high-purity recycled PET fragments and laying the foundation for subsequent high-value applications.

Detailed Breakdown of Roles and Functions
Removal of Organic Residues and Oils

Function: Residual contents originally in the bottles, such as soft drinks, fruit juices, oils, sauces, etc., leave behind organic residues like sugars, fats, and proteins. Hot water (typically combined with cleaning agents) can more effectively dissolve and emulsify these stubborn stains, which cold water washing cannot achieve.

Removal of Labels and Adhesives

Function: Labels on the bottles (usually made of PVC, PE, or paper) are firmly attached with adhesives (glue). The hot washing process softens and shrinks the label materials, breaks down the adhesiveness of the glue, and causes them to detach from the PET flakes. Simultaneously, it effectively dissolves and removes residual adhesives, preventing them from melting and contaminating the PET melt during subsequent processing.

Sterilization and Disinfection

Function: High temperatures (typically in the range of 70°C to 85°C during hot washing) effectively kill bacteria, molds, and other microorganisms that may be present during the recycling process, meeting the requirements for food-grade or high-standard hygienic materials.

Improvement of Subsequent Process Efficiency and Product Quality

Function: Thoroughly hot-washed PET flakes exhibit extremely high purity, which directly brings the following benefits:

Reduction of Impurity Carbonization: During subsequent melting and extrusion processes, organic impurities can carbonize and turn black at high temperatures, leading to black spots in the product, which affects appearance and performance. Hot washing prevents this at the source.

Ensuring Melt Quality: A pure PET melt has more stable viscosity (intrinsic viscosity, IV value) and better physical properties, facilitating fiber spinning, pelletizing, and the production of high-quality recycled PET pellets.

Meeting High-End Applications: Only thoroughly hot-washed and deeply purified rPET can be used to produce food-contact materials (such as new beverage bottles) and high-grade textile filaments, which require extremely high purity standards.