Chiterion devoted to Customizing Eco Bag Solutions for Shopping, Packaging, Delivery, Storage and Travel Since 2007
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Chiterion devoted to Customizing Eco Bag Solutions for Shopping, Packaging, Delivery, Storage and Travel Since 2007
In our daily life, many people may notice that the bottom of plastic containers is engraved with triangles with numbers (1-7).
Do you know what specifications of plastic containers each number represents? Here we explain them one by one.
01-PET （Polyethylene Terephthalate）
Common uses for polyethylene terephthalate include mineral water bottles and carbonated beverage packaging.
Polyethylene terephthalate is a common resin in everyday life. It possesses excellent mechanical properties, with an impact strength 3-5 times greater than other films, excellent folding resistance, high transparency, UV protection, and excellent gloss. Transparent plastic bottles made from it, often called "PET bottles," have a heat resistance of ≤65°C and a cold resistance of ≥-20°C, making them suitable only for holding liquids at room or low temperatures.
Precautions: If used with hot liquids or directly heated, they are susceptible to thermal deformation and the production of substances harmful to the human body. Long-term use (over 10 months) may release carcinogens. Discarding after use is recommended; do not reuse as a drinking cup or storage container.
02- HDPE (high-density polyethylene)
Common uses for high-density polyethylene include plastic containers for cleaning products, bath products, white medicine bottles, skincare products, and plastic bags currently used in supermarkets.
07- PC (Polycarbonate)
High-density polyethylene is a highly crystalline, non-polar thermoplastic resin with a melting temperature of 120-160°C. Its recommended operating temperature is 100°C or lower. In some industrial applications, it can withstand temperatures up to 110°C. Plastic bags labeled for food use can be used to store food.
Precautions: Residues in these containers can easily accumulate, breeding bacteria. Recycling is not recommended and should be promptly recycled.
03- PVC (Polyvinyl Chloride)
Common uses for polyvinyl chloride include raincoats, plastic film, and building materials.
PVC is an amorphous white powder with a low degree of branching and a relative density of approximately 1.4. Its glass transition temperature is between 77°C and 90°C, and it begins to decompose around 170°C. It is also unstable to light and heat, and temperatures above 100°C or prolonged exposure to sunlight can cause it to decompose into hydrogen chloride, leading to performance degradation.
Risks: This plastic offers excellent plasticity and is inexpensive. However, plastic products made from it are prone to producing two toxic and hazardous substances: single molecules of vinyl chloride that are not fully polymerized during the production process, and harmful substances from the plasticizer. These substances are easily released when exposed to high temperatures and oils. These toxic substances can enter the human body through food and can cause cancer. Therefore, never expose plastic to heat during use.
04- LDPE (Low-Density Polyethylene)
Common uses for low-density polyethylene include cling film and plastic film.
Low-density polyethylene, also known as high-pressure polyethylene, is a plastic material made from ethylene. It is fed into a reactor and subjected to high-pressure compression under the influence of an initiator to undergo a polymerization reaction. The material exiting the reactor is separated by a separator to remove unreacted ethylene before being melt-extruded, pelletized, dried, and blended. It is suitable for various thermoplastic molding processes and exhibits excellent processability. Low-density polyethylene is primarily used as film, but is also used in injection molding, medical devices, pharmaceutical and food packaging, and blow molding.
Precautions: Cling film made from this plastic has poor heat resistance and will melt above 110°C, potentially releasing harmful substances. Therefore, remove the cling film before microwave heating to prevent grease from dissolving harmful substances.
05- PP (Polypropylene)
Common uses for polypropylene include takeout bags and microwave-safe lunch boxes.
Polypropylene is a semi-crystalline thermoplastic. It offers high impact resistance, strong mechanical properties, and resistance to many organic solvents, acids, and alkalis. It is widely used in industry and is a common polymer material. Australian currency is also made of polypropylene. Microwaveable lunch boxes are made of this material, which is heat-resistant to 130°C and is the only plastic that can be microwaved, but it has low transparency.
Note: Some microwaveable lunch boxes are made of 05-grade PP, but the lid is made of 06-grade polystyrene. While PS has good transparency, it is not heat-resistant and should not be microwaved with the box. If the lid is 06-grade polystyrene, it should be heated separately.
06- PS (Polystyrene)
Common uses for polystyrene include instant noodle bowls and fast food containers.
Polystyrene is produced by the polyaddition reaction of styrene monomers. It was originally derived from a volatile oil in the natural resin balsam. Polystyrene exhibits excellent corrosion resistance to acids, alkalis, salts, mineral oils, organic acids, and lower alcohols, but softens or dissolves in organic solvents such as acetone, esters, and aromatic hydrocarbons. It has excellent insulation, transparency, a high refractive index, water resistance, and excellent colorability, allowing it to be made into a variety of brightly colored plastic products. Its excellent fluidity when molten makes it easy to process, allowing for molding and extrusion. Polystyrene is used in instant noodle bowls and foam fast food containers.
Risks: High temperatures release chemicals. Do not store strong acids (such as orange juice) in or microwave.
07- PC (Polycarbonate)
Common uses for PC and other PC-based products include water bottles, space cups, and baby bottles.
This widely used material, particularly in baby bottles and space cups, has been controversial due to its presence of bisphenol A (BPA). Experts point out that, in theory, as long as 100% of the bisphenol is converted into the plastic structure during the manufacturing process, the product is completely free of bisphenol A, let alone release. However, if a small amount of bisphenol is not converted into the plastic structure, it may be released into food or beverages. Therefore, when using plastic containers, strictly follow the instructions for food storage and disinfection, and avoid reusing aged or damaged products.
Recommendations: Avoid exposure to hot water, direct sunlight, or machine washing; clean with baking soda for the first time; and replace immediately if damaged.
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