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With China Plastic Machinery
With China Plastic Machinery
Cling film is a plastic packaging product, usually made by polymerization reaction with ethylene as masterbatch. Cling film can be divided into three categories: the first is polyethylene, referred to as PE; the second is polyvinyl chloride, referred to as PVC; the third is polyvinylidene chloride, referred to as PVDC.
It is widely used in occasions such as microwave food heating, refrigerator food preservation, fresh and cooked food packaging, family life, supermarkets, hotels and restaurants, and industrial production of food packaging.
Most of the cling films and commonly used plastic bags sold on the market are made of ethylene masterbatch as raw materials. According to the different types of ethylene masterbatch, cling film can be divided into three categories.
The first is polyethylene, referred to as PE, which is mainly used for food packaging. The film used for fruits and vegetables we usually buy, including semi-finished products purchased in supermarkets, is made of this material;
The second is polyvinyl chloride, referred to as PVC, which can also be used for food packaging, but it has a certain impact on human safety;
The third is polyvinylidene chloride, referred to as PVDC, which is mainly used for packaging of some cooked food, ham and other products.
Of these three types of cling film, PE and PVDC cling film are safe for the human body and can be used with confidence, while PVC cling film contains carcinogens and is more harmful to the human body. Therefore, when purchasing cling film, PE cling film should be used.
From a physical point of view, cling film has moderate oxygen permeability and moisture permeability, which regulates the oxygen and moisture content around the preserved food, blocks dust, and thus prolongs the shelf life of food. Therefore, it is necessary to use different cling films for different foods.
The cling film on the market can be roughly divided into two categories: one is ordinary cling film, which is suitable for refrigerator preservation; the other is microwave cling film, which can be used for refrigerator preservation and microwave oven preservation. The latter cling film is far superior to ordinary cling film in terms of heat resistance and non-toxicity. Therefore, consumers should pay special attention to the selection of use and use it separately.
The ideal cling film should meet the following conditions:
1. Easy to be pulled out and cut;
2. Easy to bond with glass ceramics and stainless steel pasta utensils (but not the cling film itself);
3. Nearly transparent without wrinkles, uneven thickness, etc.;
4. Able to withstand general pulling pressure.
1. Cover food containers to prevent bacterial infection.
2. Wrap food for easy storage (for example: sandwiches).
3. Refrigerate the soup bowl covered with plastic wrap to remove the oil from the soup.
The latest test shows that 15 of the 16 brands of PVC plastic wrap commonly seen in the Beijing, Shanghai and Guangzhou markets contain the plasticizer DEHA, which is banned by the state. This plasticizer can penetrate from the plastic wrap into the high-fat food packaged at room temperature, causing great harm to the human endocrine system.
Food safety expert Dong Jinshi told reporters that the plasticizers allowed by the state are generally relatively stable at room temperature, but the DEHA banned by the state can be released from the plastic wrap at room temperature and penetrate into the food, especially when packaging foods with high fat content. The main hazard of this plasticizer is that it affects the human endocrine system, leading to increased secretion of estrogen and decreased secretion of androgen, that is, precocious puberty in women and infertility in men, especially having a great impact on the genital development of infants and young children.
As early as 2005, the General Administration of Quality Supervision, Inspection and Quarantine of the People's Republic of China issued an announcement emphasizing that enterprises are prohibited from using plasticizer DEHA to produce food cling film. Beijing Kaifa Environmental Protection Technology Consulting Center purchased all brands of PVC cling film sold on the market from Beijing, Shanghai and Guangzhou, a total of 16 brands, and sent them to the national testing agency. The test results were shocking - 15 types of cling film contained DEHA, which is expressly prohibited by the state. Among them, the lowest exceeded the detection line by 98 times, the highest exceeded the detection line by 472 times, and the average exceeded the detection line by more than 200 times.
Of the 16 brands of PVC cling film, 15 contained the plasticizer DEHA banned by the state. The reporter's months-long investigation found that the PVC cling film production industry was shrouded in multiple layers of fog, and behind the fog was a lie involving the cling film industry and its upstream chemical industry.
According to the official announcement of the General Administration of Quality Supervision, Inspection and Quarantine, the plasticizer allowed to be added during the production process of PVC cling film is DOA. The reporter's investigation in Beijing, Shanghai, Jiangsu and other places also found that the raw materials used by four cling film manufacturers that were detected to contain plasticizers banned by the state were indeed labeled as DOA. During the interview in Jiangsu, DOA raw material barrels of the same company were seen in the production workshops of Wuxi Xindi Paper and Plastic Products Co., Ltd. and Taicang Junshijie Packaging Materials Co., Ltd., and the raw material barrels were marked as produced by Tongxiang Chemical Co., Ltd.
At Tongxiang Chemical Co., Ltd., Xu Xiaofeng, business manager of the company's marketing department, said that Wuxi Xindi, Shanghai Junshi and Lin Parker and other cling film companies are exclusively supplied with plasticizers by the company. At the same time, he also admitted that the DOA they provided did contain DEHA, which was unavoidable in every plasticizer production factory.
In order to verify whether what Manager Xu said was true, the reporter tested the DOA samples provided by Tongxiang Chemical Co., Ltd. and the samples of another DOA production company. The results showed that the DOA produced by these two companies did not contain DOA, but the content of DEHA was very high. It turned out that the so-called DOA was actually DEHA.
According to experts, the raw material for producing DOA is n-octanol, and the raw material for producing DEHA is isooctyl alcohol. The price of these two raw materials is very different. The price of n-octanol per ton is about 12,000 yuan, while the price of isooctyl alcohol per ton is only about 8,000 yuan. In order to reduce costs, companies use isooctyl alcohol as raw material for production. This statement was also recognized by Xu Xiaofeng, business manager of the marketing department of Tongxiang Chemical Co., Ltd. He said that in order to cope with fierce market competition, this industry is using isooctyl alcohol to produce plasticizers for plastic wrap.
So far, the source of the national banned plasticizer DEHA contained in 15 brands of PVC plastic wrap has finally come to light. According to the regulations of the General Administration of Quality Supervision, Inspection and Quarantine and relevant national standards, the main plasticizer allowed for PVC cling film is DOA, and the raw material of DOA is octanol. In order to reduce costs, upstream chemical companies that produce DOA use isooctyl alcohol, and what they actually produce is DEHA, which is banned by the country. Upstream chemical companies then sell DEHA to cling film manufacturers in the name of DOA, and eventually produce cling film that is harmful to human health.
As early as 2005, the General Administration of Quality Supervision, Inspection and Quarantine issued a special document to ban DEHA. In 2011, an agency found that PVC cling film of 5 companies contained DEHA, which was subsequently exposed by the media and investigated by law enforcement agencies. However, in 2013, the products of the 5 PVC cling film companies that had been in trouble were still found to contain DEHA in the test.
In the opinion of food safety expert Dong Jinshi, some cling film manufacturers are knowingly violating the law. Although they know that plasticizers contain DEHA, they have reached a tacit understanding with upstream chemical companies and still purchase this cheap plasticizer in the name of DOA.
The reason behind the companies' knowingly violating the law is the lack of standards. As an important food packaging material, PVC cling film has never had a national standard. The biggest advantage of not having a national standard is that companies can choose their own standards, thereby avoiding the testing of plasticizers banned by the country and the restrictions that national standards may impose on the scope of use.
Food safety expert Dong Jinshi said that the relevant agency had drafted a standard for self-adhesive cling film in 2009, covering PE, PVC and other types of cling film. The national standard for cling film, which was supposed to take effect on December 1, 2009, was postponed twice for various reasons and is still sleeping in the file cabinet.
PVC cling film has stronger transparency, stretchability and stickiness than PE cling film. When PVC cling film is burned with fire, the flame is black, black smoke is emitted, there is a pungent smell, no oil drips, and it will automatically extinguish after leaving the fire source. When PE cling film burns, the flame is yellow, odorless, and oil drips, and it can continue to burn after leaving the fire source. If it is marked as PVC material or the marking is unknown, consumers are advised not to buy and use it.
1. When heating oily food, the cling film should be kept isolated from the food and not in direct contact with each other. Because when the food is heated, the food oil may reach a very high temperature, causing the cling film to break and stick to the food.
2. When heating food, you should cover the container with cling film, and then use a toothpick or other needle-like object to poke a few small holes in the cling film to facilitate the evaporation of water and prevent the cling film from bursting due to gas expansion.
3. The highest heat-resistant temperature marked on each brand of cling film is different, and some differ by about 10¡æ. When the temperature in the microwave oven is high, it will generally reach about 110¡æ. When it needs to be heated for a long time, you can choose a cling film with higher heat resistance.
When buying a fresh-keeping box or cling film, you must pay attention to whether it is marked with a specific name or chemical structure. If there is only an English name but no Chinese label, you should be cautious when buying it. At the same time, you must choose a product marked with the words "food use".
Cling boxes are mainly made of two major materials: polyethylene (PE) and polypropylene (PP). The price difference between the two products is not large, but polypropylene (PP) can better prevent the penetration of grease.
When buying cling film, it is first recommended to buy self-adhesive cling film made of polyethylene (PE), especially when it is used to preserve meat, fruits, etc., because in terms of safety, PE cling film is the safest. If you want a longer shelf life, it is recommended to choose polyvinylidene chloride (PVDC), because this type of cling film has better moisturizing properties and has the longest shelf life among the three types of cling films. Polyvinyl chloride (PVC) cling film has become the choice of many people because of its good transparency, good viscosity, good elasticity and relatively low price, but it must be noted that it cannot be used to preserve oily foods, because it is a resin composed of polyvinyl chloride resin, plasticizer and antioxidant, and it is non-toxic in itself. However, the main auxiliary materials such as plasticizers and antioxidants added are toxic. The plasticizers in daily polyvinyl chloride plastics mainly use dibutyl terephthalate and dioctyl phthalate. These chemicals are toxic, and the oils and fats in food can easily dissolve the plasticizer "ethylamine" in the cling film, which has a great destructive effect on the human endocrine system and disrupts the body's hormone metabolism. The antioxidant lead stearate of polyvinyl chloride is also toxic. Lead salt-containing polyvinyl chloride (PVC) products will precipitate lead when in contact with ethanol, ether and other solvents. When lead salt-containing polyvinyl chloride is used as food packaging and meets fried dough sticks, fried cakes, fried fish, cooked meat products, cakes and snacks, lead molecules will diffuse into the oil, so polyvinyl chloride plastic bags cannot be used to hold oily foods. In addition, it must not be heated in a microwave oven or used at high temperatures. Because polyvinyl chloride plastic products will slowly decompose hydrogen chloride gas at higher temperatures, such as around 50¡ãC, this gas is harmful to the human body, so polyvinyl chloride products are not suitable for food packaging.
Experiments show that 100 grams of leek wrapped in plastic wrap has 1.33 mg more vitamin C after 24 hours than when it is not wrapped, and rapeseed and lettuce leaves have 1.92 mg more. However, the experimental results of some vegetables are quite different. After 100 grams of radish wrapped in plastic wrap was stored for one day, its vitamin C content decreased by 3.4 mg, beans decreased by 3.8 mg, and cucumbers lost vitamin C equivalent to 5 apples after being stored for one day and one night.
It is best not to store cooked food, hot food, oily food, especially meat, in plastic wrap. Experts point out that after these foods come into contact with plastic wrap, it is easy for the chemical components contained in the material to volatilize and dissolve into the food, which is not good for health. Most of the plastic wrap sold on the market, like commonly used plastic bags, are made of ethylene masterbatch as raw material. Some plastic wrap materials are polyethylene (PE for short), which does not contain plasticizers and is relatively safe to use; some materials are polyvinyl chloride (PVC for short), which often contains stabilizers, lubricants, auxiliary processing agents and other raw materials, which are harmful to the human body. Therefore, you must be cautious in choosing.
Food cling film is divided into several categories according to its material, such as polyethylene (also known as PE cling film) and polyvinyl chloride (also known as PVC cling film). Among them, PE cling film is mainly sold in various supermarkets, while PVC cling film is mainly used for food packaging in the fresh and bulk food areas of supermarkets. In addition, various group customers such as hotels and restaurants purchase and use it more. Among all kinds of cling film, PVC has the largest market share due to its low price, about 60% to 70%.
Yang Weimin, an expert member of the Training Expert Committee of the China Packaging Federation, told reporters that due to the production process requirements, a large amount of plasticizers, also known as plasticizers, will be added to PVC cling film during the production process. Plasticizers are insoluble in cold water, but will dissolve out at temperatures above 60 degrees Celsius or in oils and fats.
After randomly investigating ten large and medium-sized supermarkets in Beijing, the reporter found that half of the supermarkets used PVC cling film to directly wrap raw meat and cooked food. Most of the salesmen believed that PVC cling film could be used as long as it was not wrapped in hot cooked food.
Experts remind consumers that it is best to buy and use PE cling film. If PVC cling film is used, it is best not to use it directly to wrap meat, cooked food and oily foods, and it is not suitable to heat it directly in a microwave oven.
How to distinguish PVC cling film from PE cling film? Experts' advice to consumers is: 1. Look at the color. The whole roll with yellow color is PVC material, and the white one is PE. 2. Rub it with your hands. PE cling film generally has poor viscosity and is easy to open after rubbing it with your hands, while PVC cling film has better viscosity and is not easy to unfold after rubbing it with your hands. 3. Burn it. After PE cling film is ignited with fire, it burns quickly and will not go out when leaving the fire source; while PVC cling film is not easy to ignite, will go out after leaving the fire source, and has a pungent odor.
Some beauty salons have proposed using plastic wrap to lose weight, using plastic wrap made of materials such as PVC to tightly wrap the body for weight loss, believing that the low air permeability of plastic wrap can be used to increase the local body temperature, thereby achieving the purpose of burning fat and losing weight. However, some people point out that this is actually a very dangerous behavior, because the large amount of plasticizers contained in PVC can easily enter the human body through the skin and even affect the human endocrine system. Therefore, consumers must be cautious when choosing this weight loss method.
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