What is the identification mark of plastic for food packaging?

The Plastic Industry Association (SPI) has formulated the symbol code of plastic products, which is located in the middle of a triangle composed of Theory of Three Represents's one-cycle arrows, and added a digital symbol. They stick triangular recycling signs on plastic products and use the numbers 1 to 7 and English abbreviations to refer to the types of resins used in plastics. In this way, the identification of plastic varieties becomes simple and easy, and the recycling cost is greatly reduced. Nowadays, many countries in the world have adopted this SPI marking scheme. China has formulated almost the same marking standard in 1996.

The primary goal of plastic packaging waste treatment is to recycle containers as resources, so as to protect limited resources and complete the recycling of packaging containers. Among them, 28% of PET bottles for carbonated drinks can be recycled, and PE-HD bottles for milk bottles and PE-HD bottles for soda bottles can also be effectively recycled.

In order to recycle all kinds of consumed plastic products, it is necessary to classify all kinds of plastics. Because there are many and complicated channels for plastic consumption, it is difficult to distinguish some consumed plastics simply by appearance. Therefore, it is best to indicate the material variety on the plastic products. What are the uses, advantages and disadvantages of different codes? The following will help you understand this:

The plastic name code and the corresponding abbreviation code are as follows:

Polyester -0 1-PET bottles, such as mineral water bottles and carbonated beverage bottles.

Don't recycle the hot water in the beverage bottle.

Usage: heat-resistant to 70℃, only suitable for filling warm drinks or frozen drinks. It is easy to deform when filled with high-temperature liquid or heated, and harmful substances will melt out. In addition, scientists have found that plastic products may release a carcinogen DEHP after 10 months, which is harmful to testicles.

Therefore, drink bottles should be discarded after use, and should not be used as cups or containers for storing other items, so as to avoid health problems.

High density polyethylene -02-HDPE, such as cleaning products and bath products.

If the cleaning is not thorough, it is recommended not to recycle.

Usage: It can be reused after careful cleaning, but these containers are usually not easy to clean, leaving the original cleaning supplies and becoming a hotbed of bacteria. You'd better not recycle them

Pvc-03-PVC such as: some decorative materials.

Usage: This material is easy to produce harmful substances at high temperature, and even releases harmful substances during the manufacturing process. When toxic substances enter the human body with food, it may cause diseases such as breast cancer and birth defects of newborns. At present, containers made of this material are rarely used for packaging food. If it is in use, don't let it get hot.

Low density polyethylene -04-LDPE, such as plastic film, plastic film, etc.

Don't put plastic wrap on the surface of food and put it in the microwave oven.

Uses: heat resistance is not strong. Generally qualified PE plastic wrap will melt when the temperature exceeds 1 10℃, leaving some plastic preparations that cannot be decomposed by human body. Moreover, when food is wrapped in plastic wrap and heated, the oil in food can easily dissolve the harmful substances in plastic wrap. Therefore, before putting food into the microwave oven, the plastic wrap of the package must be removed first.

Polypropylene-05-polypropylene (can withstand the temperature above 100 degrees), such as microwave lunch boxes.

When you put it in the microwave oven, take off the cover.

Usage: The only plastic box that can be put into the microwave oven can be reused after careful cleaning. It should be noted that some microwave lunch boxes are indeed made of No.5 PP, but the lid is made of No.0 PE/kloc-0. Because PE can't withstand high temperature, it can't be put in the microwave oven with the box. For the sake of safety, please open the lid of the container before putting it into the microwave oven.

Polystyrene -06-PS (heat resistance 60-70 degrees, hot drinks will produce toxins, and styrene will be released when burning), such as instant noodle boxes in bowls and fast food boxes.

Don't cook a bowl of instant noodles in the microwave oven.

Usage: It is heat-resistant and cold-resistant, but it can't be put into the microwave oven to avoid releasing chemicals when the temperature is too high. And it can't be used to load strong acids (such as orange juice) and strong alkaline substances, because it will decompose polystyrene which is not beneficial to human body and is easy to cause cancer. Therefore, you should try to avoid packing hot food in fast food boxes.

Other plastic codes -07- others, such as: kettle, water cup, milk bottle.

PC glue releases bisphenol A when heated.

Uses: A widely used material, especially in milk bottles, is controversial because it contains bisphenol A. Lin Hanhua, an associate professor in the Department of Biology and Chemistry of the City University of Hong Kong, said that in theory, as long as 100% of bisphenol A is converted into plastic structure in the process of manufacturing PC, it means that the product does not contain bisphenol A at all, let alone is released. However, if a small amount of bisphenol A is not converted into the plastic structure of PC, it may be released into food or drink. Therefore, be careful and pay special attention when using this plastic container.

Cleaning measures to deal with bisphenol A:

The higher the temperature, the more bisphenol A remaining in PC is released, and the faster it is released. Therefore, do not use PC water bottles to bottle hot water, so as not to increase the release speed and concentration of bisphenol A (if any). If your kettle number is 7, the following methods can reduce the risk:

● Do not heat when using.

● Do not use the dishwasher or bowl dryer to clean the kettle.

● Don't let the kettle be exposed to direct sunlight.

● Before the first use, wash it with baking soda and warm water, and naturally dry it at room temperature. Because bisphenol A will release more during the first use and long-term use.

● If the container is injured or damaged, it is recommended to stop using it, because if there are tiny pits on the surface of plastic products, it is easy to hide bacteria.

● Avoid reusing aging plastic appliances.

Among them, PP, PE and PVC are abbreviations of English names. The Chinese names are polypropylene, polyethylene and polyvinyl chloride, and the English full names are polypropylene, polyethylene and polyvinyl chloride.

Some of our common old slippers are made of PVC. They are soft in summer and hard in winter, which is closely related to the temperature sensitivity of PVC. PVC will decompose toxic gas-chlorine at high temperature. Among these three materials, PVC has the highest density.

Ordinary plastic bags are made of PE and have good toughness. PE is also divided into HDPE (high density polyethylene) and LDPE (low density polyethylene), and some of its properties are very different due to different densities.

PP is a relatively safe plastic, and the packaging bags on general foods are made of it. Of course, PP also has grades, and the food used for packaging food must be food grade. PP has the lowest density among the three and can float on the water.

Generally speaking, these polymer materials can be modified by adding some other materials to make them superior in overall performance or a certain aspect, so as to be used for special purposes. Of course, the price will sometimes increase greatly after modification.

The following methods can be used to detect toxic and non-toxic plastic bags:

Sensory detection method: non-toxic plastic bags are milky white, translucent, or colorless and transparent, elastic, smooth to the touch and waxy on the surface; Toxic plastic bags are turbid or yellowish in color and sticky to the touch.

Water detection method: put the plastic bag into the water and press it into the bottom. Non-toxic plastic bags have a small proportion and can surface, while toxic plastic bags have a large proportion and will sink.

Jitter detection method: grab one end of the plastic bag by hand and shake it vigorously, so that the person who makes a crisp sound is nontoxic; Dull sounds are poisonous.

Fire detection method: Non-toxic polyethylene plastic bags are flammable, with blue flame and yellow top, dripping like candles and tears when burning, with paraffin smell and less smoke; Toxic PVC plastic bags are non-flammable. They go out immediately after leaving the fire source. The flame is yellow, the bottom is green, it can be softened and stretched, and it has a pungent smell of hydrochloric acid.