Plastic bottles are primarily made from materials such as polyethylene terephthalate (PET), high-density polyethylene (HDPE), and polypropylene (PP). To facilitate recycling and sorting, an international identification system is commonly used, featuring a triangle containing a number (ranging from 1 to 7) to classify the plastic type.
"No. 1" denotes PET (polyethylene terephthalate), which is most commonly used for bottled beverages such as mineral water and carbonated drinks. PET is odorless, lightweight, chemically stable, and offers good sealing properties. It withstands temperatures ranging from -20°C to 65°C; while suitable for warm or cold beverages, it is prone to deformation and the leaching of substances harmful to human health when exposed to high-temperature liquids or heating. During use, PET bottles may release antimony-a harmful metal catalyst-and repeated use may lead to the leaching of plasticizers such as phthalates. Reusing empty beverage or mineral water bottles to store condiments like vinegar or alcohol may increase the migration of toxic substances. Research indicates that bottled water contains an average of approximately 6 million plastic particles per liter-mostly nanoplastics-originating primarily from the bottle itself (PET material) and the cap; these particles can enter the human body through consumption, prompting recommendations to reduce bottled water intake to lower the risk of microplastic exposure.
"No. 2" denotes HDPE (high-density polyethylene); plastic containers for cleaning agents and bath products are frequently made from this material. HDPE can withstand temperatures up to 110°C and is safe for food storage if labeled as food-grade. Containers originally used for cleaning agents or bath products can be reused after thorough cleaning.
"No. 5" denotes PP (polypropylene), the only plastic material suitable for microwave heating. PP withstands temperatures up to 130°C and has a melting point as high as 167°C; although it has low transparency, it can be reused after careful cleaning.
Other numbered categories (3, 4, 6, and 7) are also used for specific types of plastic bottle packaging. In the personal care and household products industry, plastic bottle materials are diverse; beyond PET, they include high-density polyethylene (HDPE) and clear polypropylene (CPP). Key trends include the adoption of in-mold labeling technology to elevate packaging quality, as well as the development of eco-friendly packaging materials such as biodegradable plastic containers, nanocomposite plastic containers, and antimicrobial plastic bottles.
