Introduction and taboos of five common plastic bottles
1. Polyethylene terephthalate (PET)
Polyethylene terephthalate (polyethylene terephthalate), referred to as PET or PETE, commonly known as polyester resin. It is a durable thermoplastic material that exhibits strong resistance to chemicals, high-energy radiation, moisture, erosion, and abrasion. Depending on processing and heating, PET can appear transparent or semi-crystalline. However, PET can be added in different colors depending on the application. It is worth noting that PET does not contain polyethylene, although the name contains (polyethylene).
One of the main uses of PET is plastic bottles and other plastic containers, such as mineral water bottles, beverage bottles, bakery product containers, etc.; because it is very easy to prepare into various shapes, it is suitable for holding cosmetics; PET film can be used to make balloons, food bags, space blankets; also used as salad trays, salad decorations, and jars for medicine.
2. High Density Polyethylene (HDPE)
High-density polyethylene (HDPE) is a semi-elastic hard plastic that is easily produced by catalyst polymerization in suspension, solution, or gas-phase reactors. It is chemical resistant, moisture resistant, resistant to the effects of any situation, but not resistant to high temperatures above 160°C.
HDPE is opaque but can be coloured on request. HDPE products are safe for storing food and drinks, so it is used in shopping bags, freezer bags, milk bottles, ice cream boxes and juice bottles. It is also used in shampoo and seasoning bottles, soap bottles, dish soap, bleach, and agricultural plumbing.
3. Polyvinyl chloride (PVC)
Polyvinyl chloride (PVC) comes in two forms, one is rigid non-plastic polyvinyl chloride (PVC-U) and the other is elastic plastic polyvinyl chloride (PCV-P). PVC can be produced from ethylene and salt by the polymerization of vinyl chloride.
PVC is fire resistant due to its high chlorine content and is also resistant to oils and chemicals (except aromatics, ketones and cyclic ethers). PVC is durable and can withstand aggressive environmental factors. PVC-U is used in warm water pipes and fittings, curtain wall glass, roof sheet steel, cosmetic containers, bottles, windows and door frames. PVC-P is commonly used as cable jackets, blood bags and tubing, watch straps, garden hoses, and shoe soles.
4. Polypropylene (PP)
Polypropylene (PP) is a strong and elastic thermoplastic that can withstand high temperatures of 200°C. PP is made from propylene gas under the action of a catalyst such as titanium chloride. As a lightweight material, PP has high tensile strength and high resistance to corrosion, chemicals and moisture. Also, it can be colored in a variety of ways without compromising quality.
Relative to the higher melting point of other plastics, PP can be used to make food containers that can be used in high temperature places such as microwave ovens. (Attention! It's the only microwave-safe plastic we come into contact with in our daily lives)
PP can be used to make bubble bottles and ice cream tubs, butter boxes, potato chip bags, straws, microwave dinner plates, water bottles, garden furniture, lunch boxes, prescription bottles and blue packing tape. PP can also be used to make plastic parts, such as plastic toys and mobile phone casings and protective cases.
5. Low density polyethylene (LDPE)
Low density polyethylene (LDPE) is softer and more elastic than high density polyethylene (HDPE). LDPE is obtained by polymerizing ethylene under high pressure in a high pressure steam or tubular reactor. It has good chemical resistance and good electrical properties, high impact strength at low temperature.
LDPE is compatible with most food and household chemicals and acts as an oxygen-poor barrier. It is used for stretch wrapping because of its molecular structure that gives it high elongation.
LDPE is mainly used in plastic food packaging, garbage bags, squeeze bottles, black irrigation pipes, trash cans, plastic shopping bags.
These five kinds of plastics are very common in our daily life, and most of them deal with food. But not all plastics can hold food without restrictions. So, how to distinguish? Here's a little trick.
The Plastics Industry Association has developed a set of plastic recycling symbols that divide plastics into 7 categories, each number representing a type of plastic. Although it is a recycling symbol, it is also a health symbol.
No. 01: PET material. It is not suitable for high-temperature liquids, nor for heating. High temperature can easily dissolve substances harmful to human body. It may release carcinogens after 10 months of use, so throw it away after use and don't use it to fill a water bottle.
No. 02: HDPE material. Easy to clean is not thorough, it is best not to recycle.
No. 03: PVC material. Cannot be used for food serving.
No. 04: LDPE material. When the temperature exceeds 110 degrees, the phenomenon of hot melting occurs, and the plastic preparations that cannot be decomposed by the human body are melted.
No. 05: PP material. Can be reused after careful cleaning.
No. 06: PS material (polystyrene). No high temperature, strong acid, strong alkaline food or drink.
No. 07: Other plastics, mainly PC (polycarbonate). It is not advisable to use a PC for hot water.