Knowledge of Plastic Bags - Chapter 3.
International ban
Ireland has imposed a 0.15 euro tax on the purchase of plastic bags since 2002, and has reduced the use of plastic bags by 90% since the implementation.
Rwanda abandoned the use of plastic bags in 2005.
Israel, Canada, Western India, Botswana, Kenya, Tanzania, South Africa, China, Singapore, etc. have all banned or are about to ban plastic bags.
On March 27, 2007, San Francisco became the first city in the United States to ban plastic bags.
American cities Oakland and Boston are also considering whether to ban plastic bags.
Since the raw materials of plastic bags contain some components of oil, China can save 37 million barrels of oil every year after banning free plastic bags.
On June 1, 2008, China banned free plastic bags. Small quality plastic bags are prohibited.
Single-use plastic bags will be phased out by the state's grocery stores and other retailers by 2016, according to a new regulation signed Tuesday by California Governor Jerry Brown, Oct. 1, 2014. .
On September 18, 2022, local time, the Ministry of Commerce, Industry and Investment Promotion of Oman announced that Oman will ban the import of plastic bags from January 1, 2023.
Kind of plastic
Classified by raw materials:
(1) High pressure polyethylene plastic bag
(2) Low pressure polyethylene plastic bag
(3) Polypropylene plastic bags
(4) PVC plastic bags
(5) Vinyl acetate (EVA)
(6) Polyethylene + vinyl acetate (PE + EVA mixture)
(7) Polyethylene-coated polypropylene (PE/PP)
(8) Polyethylene clad with vinyl acetate (PE/EVA)
(9) Polyethylene-coated polyvinyl chloride (PE/PVC)
(10) Polyethylene-coated nylon (PE/Nylon) (PE/PA)
(11) Polyethylene-coated polyethylene terephthalate (PE/PET)
(12) Polypropylene laminated polypropylene (PP/PP)
Classification by shape:
(1) vest bag
(2) Straight bag
(3) Sealing pocket
(4) Adhesive bag
(5) Special-shaped bag
Identify qualified methods
1. First of all, check whether the appearance of the plastic bag has a "food use" mark. Usually this logo should be on the front of the packaging bag in a more prominent position. The second is to look at the color. Generally speaking, most of the colored plastic bags use recycled materials of waste plastics, which cannot be used to store food. For example, some black plastic bags used to store fish, shrimp and other aquatic products or meat in vegetable markets were originally used to store garbage, and consumers should avoid using them. Finally, look at the plastic bags for impurities. Put the plastic bag in the sun or light to see if there are black spots and holes. Plastic bags with impurities must be made of waste plastics as raw materials.
2. Smell the plastic bag to see if there is any odor, whether it makes people feel sick. Qualified plastic bags should be odorless, and unqualified plastic bags will have various flavors due to the use of additives.
3. Qualified plastic bags have a certain strength and will not break as soon as they are torn; unqualified plastic bags are often poor in strength and easy to break due to the addition of impurities.
4. When the qualified plastic bag shakes, it will make a crisp sound; the unqualified plastic bag is often a "humming" muffled sound.
5. Put the plastic bag in the water, and press it to the bottom of the water by hand, wait for a while, the non-toxic plastic bag that surfaced is the non-toxic plastic bag, and the one that sinks to the bottom is the toxic plastic bag.
6. Touch the surface of the plastic bag with your hand, it is very smooth and non-toxic. If the color is blurred, sticky and astringent to the touch, it is poisonous.
7. Burning: Cut a corner of the plastic bag and burn it on the fire. The non-toxic one will burn immediately. After it leaves the fire, it will continue to burn, and a yellow flame will appear, and the molten plastic will drop drop by drop like a candle. , emits the smell of paraffin; poisonous, not easy to burn, after burning it turns green flames, and has a pungent odor.
Plastic bags contain less hot and oily food. Of course, if you're not sure if a plastic bag is safe, avoiding it for overheated or greasy foods is one way to reduce the harm. Expert Lu Sihao said that unsafe plastic bags mainly contain harmful substances such as dyes and heavy metals. The oil contained in oily foods such as meat, fish, and fried dough sticks is actually a solvent, which can precipitate harmful substances in plastic bags; and high temperature will soften the plastic, which can also promote the precipitation of harmful substances, resulting in poisoning. Therefore, it is relatively safe to pack vegetables or frozen food at room temperature. Of course, try not to use plastic bags to store food. You can bring your own basket or cloth bag when buying groceries. When you have to use it, you should also take out the food in the plastic bag as soon as possible after returning home.
plastic composition
The plastic we usually use is not a pure substance, it is formulated from many materials. Among them, high molecular polymers (or synthetic resins) are the main components of plastics. In addition, in order to improve the performance of plastics, various auxiliary materials, such as fillers, plasticizers, lubricants, stabilizers, etc., are added to the polymer. Colorants, etc., can become plastics with good performance.
Synthetic resin
Synthetic resin is the main component of plastic, and its content in plastic is generally 40% to 100%. Due to the large content and the properties of resins that often determine the properties of plastics, people often regard resins as synonymous with plastics. For example, polyvinyl chloride resin is confused with polyvinyl chloride plastic, phenolic resin and phenolic plastic. In fact, resin and plastic are two different concepts. Resin is a raw, unprocessed polymer that is used not only to make plastics, but also as a raw material for coatings, adhesives, and synthetic fibers. In addition to a very small part of plastics containing 100% resin, the vast majority of plastics need to add other substances in addition to the main component resin.
filler
Fillers, also known as fillers, can improve the strength and heat resistance of plastics and reduce costs. For example, adding wood powder to phenolic resin can greatly reduce the cost, making phenolic plastic one of the cheapest plastics, and at the same time, it can significantly improve the mechanical strength. Fillers can be divided into organic fillers and inorganic fillers, the former such as wood flour, rags, paper and various fabric fibers, etc., the latter such as glass fiber, diatomaceous earth, asbestos, carbon black and so on.
Plasticizer
Plasticizers can increase the plasticity and softness of plastics, reduce brittleness, and make plastics easy to process and shape. Plasticizers are generally resin-miscible, non-toxic, odorless, high-boiling organic compounds that are stable to light and heat. The most commonly used are phthalates. For example, in the production of polyvinyl chloride plastics, if more plasticizers are added, soft polyvinyl chloride plastics can be obtained; if no or less plasticizers are added (the amount is less than 10%), rigid polyvinyl chloride plastics can be obtained .
stabilizer
In order to prevent the synthetic resin from being decomposed and destroyed by light and heat during processing and use, and to prolong the service life, a stabilizer should be added to the plastic. Commonly used are stearate, epoxy resin and so on.
Colorant
Colorants can give plastics a variety of bright, beautiful colors. Organic dyes and inorganic pigments are commonly used as colorants.
lubricant
The role of the lubricant is to prevent the plastic from sticking to the metal mold during molding, and to make the surface of the plastic smooth and beautiful. Commonly used lubricants are stearic acid and its calcium and magnesium salts.
In addition to the above additives, flame retardants, foaming agents, antistatic agents, etc. can also be added to the plastics to meet different application requirements.
