Classification of common plastic products
Ordinary plastic products will have above markings on bottom, which determine range of use. Cookware marked with these numbers is a qualified product, but if misused, it will become poisonous. 1. PET: polyethylene terephthalate
It is often used to make mineral water bottles, cola drink bottles, juice bottles, screen protectors and other transparent protective films, etc. It is usually colorless and transparent. Because it can only withstand heating up to 70 ° C, this kind of beverage bottle is only suitable for cold and warm drinks. It is easy to deform when filled with high-temperature liquids (such as hot water) or when heated, and substances harmful to human body will be dissolved, and a plastic product after 10 months of use can release carcinogens that are toxic to human body. PET can also be spun, which we often refer to as polyester. That's why there is a saying during Olympics that drink bottles are recycled to make clothes. Many types of sportswear that provide breathability and lightness are made of polyester, and popular clothing material "dacron" is also made of polyester, but limited at time by reverse rotation methods, Dacron clothing is not as comfortable to wear as it is now. In addition, PET also has many engineering applications. Commonly used for filling mineral water, carbonated drinks, fruit juices, etc. Advantages: high transparency, contents of bottle can be clearly seen; acid and alkali resistance, withstands carbonated drinks; High water resistance, difficult to seep. Note: Non-toxic, but monomers, low molecular weight oligomers and reaction by-products such as diethylene glycol may remain during synthesis. All of them are toxic to some extent. The country has strict standards for PET raw materials used. in beverage bottles. PET plastic bottles can not be put in car to bask in sun, do not contain alcohol, oil and other substances, harmful substances are easily dissolved. Do not fill liquids with temperatures above 70°C, too high temperatures will decompose the material and release harmful chemicals. 2. HDPE: high density polyethylene
Suitable for food and medicine, cleaning and bathing products, shopping bags, trash cans, etc. At present, most of plastic bags used in supermarkets and shopping malls are made of this material, which withstands high temperatures up to 110°C, and plastic bags labeled for food can be used to store food. HDPE is widely used in various translucent and opaque plastic containers and appears to be thicker. Commonly used in: white medicine bottle, opaque shampoo bottle, yogurt bottle, chewing gum bottle, etc. Advantage: more resistant to various corrosive solutions, in mainly used in cleaning products, bath products, etc. Note: Bottles of cleaning products and bath products can be reused after cleaning, but these containers are usually not washed, and residual substances will become a breeding ground for bacteria, it is better not to recycle they are all more not recommended as recycling containers. Use in food and medicine containers. 3. PVC: polyvinyl chloride
PVC is currently mainly used to make cheap artificial leather, floor mats, sewer pipes, etc.; because of its good electrical properties and inherent fire resistance, it is widely used in manufacture of wire and cable sheaths. . In addition, PVC is widely used in industrial areas, especially in places with high requirements for acid and alkali resistance. It is used in: raincoats, PVC plastic pipes, water pipes, plastic switches, sockets. Advantages: high strength, weather resistance and good corrosion resistance. Note: This material can only withstand temperatures up to 81°C, so it should not be used in areas with higher temperatures. In production of PVC, a large number of plasticizers (plasticizers such as DOP) and heat stabilizers containing heavy metals are used, and it is difficult to eliminate presence of free monomers in synthesis process. When faced with high temperature and oil, toxic substances are easily precipitated, which is easy to cause cancer, so PVC is mainly replaced by PP and PE in contact with human body, especially in medical and food applications.
4. Low Density Polyethylene (LDPE)
Plastic film and PE film, milk cartons, beverage cartons and other paper packaging boxes are used as inner film. It is mainly used on plastic film and other tableware, and is not suitable for beverage containers. Commonly used in plastic wrap, plastic film, toothpaste or facial cleanser tube packaging. Advantages: good plasticity, very wide application in everyday life. Note: LDPE products soften or even melt at higher temperatures, so try to avoid using them above 100°C. The plastic film will melt when temperature exceeds 110°C. Therefore, remove plastic film before placing food in microwave.
5. Polypropylene (PP)
Microwave lunch boxes are made from this material, which can withstand high temperatures up to 130 °C and have poor transparency. This is only plastic box that can be microwaved and reused after thorough cleaning. PP has high hardness and glossy surface. PP is also used in a wide range of daily necessities such as packaging, toys, washbasins, buckets, hangers, cups, bottles, etc., as well as engineering applications such as car bumpers. Polypropylene spun into silk is called polypropylene, which is very common in textiles, nonwovens, ropes, fishing nets and other products. Commonly used in: Disposable fruit juice, drink glasses, plastic dinner plates, LocknLock fruit and vegetable containers, etc. Advantages: Good air permeability, heat resistance up to 167℃, it is lightest plastic container. Note: If temperature is too high, there will still be gases that are not suitable for diffusion of human body. In addition, body of some microwave lunch boxes is made of PP and lid is made of PS #6. Check carefully before use. If this situation occurs, you should remove lid first and then heat it. Compared to polyethylene products, polypropylene products have slightly better heat resistance. A regular Lock&Lock glass can be used at 110°C, but any higher temperature can lead to softening and melting, which should be avoided as much as possible. 6. Polystyrene (PS)
When temperature is too high, harmful substances are released from it. It must not be heated in microwave. It is divided into two types: foamed and non-foamed: foamed is a regular foam lunch box; non-foamed, such as yogurt bottles; unfoamed, slightly folded, will have white marks, can usually be torn apart by hand. Commonly used in: ice cream containers, fast food boxes, cheap transparent products, plastic foam, CD boxes, water glasses, fast food boxes, thermal insulation material layers, etc. Advantages: Excellent transparency and heat resistance, often used to store high-temperature products such as instant noodle bowls (paper containers are often used now), good frost resistance, and all kinds of ice chips are used in this. container. Attention: When PS collides with strong acids and strong alkalis, harmful substances are formed. Be careful when using PS cookware and do not put acidic or alkaline foods. Do not use snack boxes to pack hot meals and do not cook instant noodles in bowls. In addition, polystyrene is highly flammable, especially polystyrene after foaming. During combustion, a large amount of toxic gases are released. In some high-rise building fires, since widely used PS foam board was used as insulation layer material, a large amount of thick smoke and poisonous gas generated after fire was main cause of a large number of casualties. 7. Polycarbonate (PC or OTHER)
It is synthesized from bisphenol A and diphenyl carbonate and is often used to make teapots, cups and baby bottles. In process of making PC, original bisphenol A must completely become a plastic structural component and should not be released during use, but low-quality products cannot do this, and a small part of bisphenol A cannot be completely converted into plastic, and it will be damaged when heated. in food, harmful to children and fetus. (Because of this, PC baby bottle incident occurred in 2011.) At present, water glasses are most common material for glasses, many department stores and car manufacturers use water glasses made from this material as gifts. General Use: Often used in clear water cups, feeding bottles, drinking buckets, CD-pads, lenses and lampshades in everyday life. Advantages: good light transmission, good heat resistance and impact resistance, resistance to weak acids, weak alkalis and neutral oil. Note: Poor UV and weather resistance, surface is not wear-resistant and easily scratched, not strong alkali resistant. 7. Polyamide (PA or OTHER)
Another name for polyamide: nylon. You must be familiar with it. The polyamide family is very powerful and there are many varieties, each with excellent physical and chemical properties. This is also reason why polyamide is widely used in electronics and automotive industries. In life, nylon rope and nylon socks are also common items. The molded polyamide fiber is called nylon and is used in fishing lines, fishing nets, ropes, conveyor belts, etc. Commonly used in: nylon rope, nylon stockings, fishing line, fishing net, rope and conveyor belt, etc. Advantages: Nylon is non-toxic, has good temperature resistance, especially heat resistance, not easy deformed, so it can be used even in manufacture of engine parts. Note: Nylon has poor breathability and is prone to static electricity. 7. ABS (acrylonitrile butadiene styrene copolymer) (ABS or OTHER)
There are many types of ABS, which are widely used in various electrical enclosures, stationery components, safety helmets, door and window pipes, etc. ABS is often used in mixing and modifying other plastics in industry. Use Caution:ABS plastic is non-toxic, but is mainly used as a structural material and is rarely used for packaging everyday items. ABS has many advantages, but it still shares characteristics of plastics: it is not heat resistant. 7. Blend (XX-XX alloy) (OTHER)
Because it is difficult for a single plastic to meet complex requirements, plastics industry often mixes different plastics to obtain plastic alloys, which can not only take full advantage of different materials, but also save cost of developing new materials. Main applications:Plastic alloys are widely used in various structural materials. For example, mobile phone cases are mostly made from PC-ABS alloys; some sewer pipes are made from two types of polyethylene alloys to meet performance and processing needs, called bimodal polyethylene. Note:Although advantages of various plastics are combined, material is still plastic and heat resistance is still biggest disadvantage. However, most products will not be exposed to high temperatures in practical applications. As long as you pay attention to application environment, plastic is definitely a good and cheap material.