Commonly used food packaging plastic bags are mostly made of polyethylene film, which is non-toxic, so it can be used to hold food. There is also a film made of polyvinyl chloride, which is also non-toxic, but the additives added according to the purpose of the film are often harmful to the human body and have certain toxicity. Therefore, this type of film and plastic bags made of this film are not suitable for holding food. It can also stick to things for easy operation.

Making raw materials

Polyethylene, referred to as PE. It is a high-molecular organic compound formed by the addition polymerization of ethylene. Polyethylene is recognized as the best material for contact with food in the world. It is non-toxic, tasteless, and odorless, and meets the sanitation standards for food packaging. Polyethylene film is light and transparent, and has the properties of moisture resistance, oxidation resistance, acid resistance, alkali resistance, general air tightness, and excellent heat sealing. It is the most used and most important material for plastic packaging printing.

PVC--Polyvinyl Chloride

Polyvinyl chloride is referred to as PVC, with a molecular formula of (CH2-CH2)n. It is the most important type of vinyl polymer and the second largest plastic variety in the world after polyethylene.

Shrinkfilm--Shrink film

Shrink film (Shrinkfilm) is a thermoplastic film that is stretched and oriented during the production process and shrinks when exposed to hot air or infrared radiation during use. After heat treatment, the film is tightly wrapped around the packaged object, and the shrinkage force reaches the maximum value during the cooling stage and can be stored for a long time.

LDPE--Low-density polyethylene

Low-density polyethylene, referred to as LDPE, is the largest variety used in the plastic packaging and printing industry in various countries. The specific gravity is 0.92-0.93 and can float on water. The crystallinity is low (60%), and the bulk polymerization is carried out at a pressure of 1000-3000kg/C©O, so it is also called high-pressure polyethylene. At 23 degrees Celsius, the density is about 0.92. It is suitable for food packaging, fiber product packaging, and daily chemical product packaging.

HDPE--High-density polyethylene

High-density polyethylene, referred to as HDPE. It is polymerized at low pressure, so it is also called low-pressure polyethylene. It is milky white with poor surface gloss. The film can be processed by blow molding and T-die extrusion. It is heat-resistant, cooking-resistant, cold-resistant, freezing-resistant, moisture-proof, gas-proof and insulating. It is not easy to break and has a strength twice that of LDPE. It is very easy to open.

BOPP--Biaxially oriented polypropylene film

Biaxially oriented polypropylene film, also known as biaxially oriented polypropylene film, has the English abbreviation code BOPP. It is characterized by oriented stretch molecules, and its mechanical strength, folding strength, air density and moisture-proof barrier properties are better than ordinary plastic films. Compared with cellophane per unit area, the unit price is lower than that of cellophane. Because this film has excellent transparency, the color reproduced after printing is particularly bright and beautiful, and it is an important substrate for plastic composite flexible packaging.

Printed plastic bags have the following requirements for the use characteristics of ink

Modern printing equipment is developing towards one-time multi-color online printing, so the ink needs to have the characteristics of rapid drying, that is, the ink is quickly fixed and dried after being transferred to the printing material to meet the requirements of high-speed multi-color continuous printing of the equipment.

, it will not dry and form a crust quickly on the ink fountain and rubber roller of the printing machine, so as not to hinder normal printing, thereby better ensuring the printing quality and work efficiency. 3. The ink is required not to react chemically with the printing plate, not to corrode the printing plate, and not to reduce the printing resistance of the printing plate. The color of each batch of the same type of ink in the printing plastic bag should be the same, the membrane is firm, it will not fade after printing, and it can produce light after overprinting. In addition to transparent ink, each color ink should have a certain covering power, and after overprinting, the overprinted ink should maintain the original basic color characteristics.

Toxicity identification

Polyethylene film (non-toxic)

The film is milky white and translucent (especially obvious when observed when several layers are stacked together), feels smooth, as if there is a wax layer on the surface, shakes hard, makes a crisp sound, is flammable when exposed to fire, has a yellow flame, and has mucus dripping when burning, and has the smell of burning candles. Such as: PE

Polyvinyl chloride film (generally toxic)

Law

The General Office of the State Council issued a notice on "Restricting the production, sale and use of plastic bags", which requires all supermarkets, shopping malls, bazaars and other commodity retail places to implement a paid use system for plastic bags, and no plastic bags shall be provided free of charge.

The "Notice of the General Office of the State Council on Restricting the Production, Sale and Use of Plastic Shopping Bags" (commonly known as the "Plastic Restriction Order"), which was implemented in June 2008, has been in effect for two years. According to Dong Jinshi, the initiator of the "Plastic Restriction Order" and Secretary-General of the International Food Packaging Association, the use of plastic shopping bags in large supermarkets has decreased by 70% in the past two years. However, due to the relaxation of supervision and the lack of any punishment measures, the use of plastic bags has "resurrected", especially in meat and vegetable markets and small shops, which are the "hardest hit areas" where plastic restrictions are ineffective. The owner of the Yide Road plastic bag wholesale stall told reporters that the wholesale volume of plastic bags has increased by about 20% compared with last year.

Wholesale volume of plastic bags increased by 10% to 20%

Reporters visited packaging material shops on Yide Road and found that sales of various plastic bags have recovered. Fang Jie is the owner of a plastic bag shop. She said that when the plastic restriction order was first issued, there were indeed fewer people coming to buy goods. They also started to make wool-spun eco-friendly bags. For a period of time, eco-friendly bags were even better than plastic bags. "Later, the management was relaxed, and more people used plastic bags. Now no one cares." She said that the sales volume of plastic bags increased by 10% to 20% compared with last year.

The plastic restriction order requires that the production, sale and use of plastic shopping bags with a thickness of less than 0.025 mm be prohibited. Aqi, the owner of a plastic bag stall, admitted that there are indeed many more thick plastic bags, but the materials are just slightly thicker, and they are not degradable plastics.

Jian Lina, secretary general of the Guangzhou Chain Operation Association, said that large shopping malls and supermarkets have implemented the plastic restriction order well, and the difficulty in implementation lies in small businesses and meat and vegetable markets. "The enforcement this year is not as strong as last year, and the use of plastic bags has rebounded." Regarding the market situation, Jian Lina said that the Municipal Development and Reform Commission had taken the lead in organizing the industrial and commercial departments and the Chamber of Commerce to conduct inspections, but no further inspections were conducted.

Plastic bags are unlimited in the meat and vegetable market

I have been carrying a red basket to the market to buy vegetables every day for two years, but the nostalgic basket has been neglected and replaced by red, white and blue plastic bags. "The market provides plastic bags for free again." Ms. Kong told reporters about this change. Ms. Jiang also said that the Siyou Market "restricted" for a while when the plastic restriction order was first issued, but later some stall owners used it in secret, but they were open and gave as much as they wanted. Ms. Li told reporters that the Jinyayuan Market on Binjiang East Road has never restricted the use of plastic bags.

"Plastic restrictions have no effect on street markets." Ms. Li believes that it is unrealistic not to use plastic bags to pack vegetables when they are wet and dirty. Some markets provide fresh-keeping bags, but they are more expensive than low-end plastic bags. In order to save costs, meat and vegetable stall owners have to use ordinary plastic bags.

According to the calculation that a meat stall gives out 100 plastic bags every day, 36,500 plastic bags are used in a year. "Meat and vegetable markets are the hardest hit areas where plastic restrictions cannot be controlled." Dong Jinshi frankly admitted in his summary of the two-year plastic restriction that the enforcement of the plastic restriction order is weakening year by year, especially in some meat and vegetable markets where there is no trace of plastic restrictions.

Disposal methods

Can smelly feces become items needed in daily life? This is not a science fiction novel, but a real realization by a group of young American entrepreneurs who have just graduated from college. This idea sounds incredible, but after careful study, people have to admire its creative ingenuity. These young entrepreneurs use microorganisms to digest the carbon in organic fertilizers and turn it into raw materials for plastic bags. After being discarded, plastic products made from this raw material can be degraded in about a year. In this way, not only can the problem of fecal disposal be solved, but also the pollution of plastic to the environment can be reduced, and the dependence of plastic products on oil can be reduced.

This plastic product can not only be degraded in the landfill after being discarded, but also can be degraded after being implanted in the human body. It has no toxic side effects and will not produce inflammation and other rejection phenomena. This makes this plastic have great application prospects in biomedicine, such as absorbable medical sutures, temporary stents or catheters that do not need to be removed.

The average degradation time of this PHA plastic is one and a half years. If it is placed on a shelf or in a cupboard, it can be stored for a longer time. But if it is thrown into a landfill, a compost pile or even the ocean, it will degrade quickly without leaving any harmful substances. According to statistics, there are 100 million tons of non-degradable plastics floating in the North Pacific Ocean, endangering marine life and destroying the food chain. The application of this new technology is expected to greatly reduce the damage of plastic to the environment.

The traditional way of treating feces is mainly incineration or chemical treatment. These methods are costly and will convert organic carbon elements into a large amount of carbon dioxide and release it into the atmosphere, aggravating the greenhouse effect. Traditional plastics are extracted from petroleum, which converts limited petroleum into non-degradable white garbage, which harms the environment. This innovative technology kills two birds with one stone, cleverly using the transformation of microorganisms in nature to "turn feces into treasure", reducing pollution while generating economic benefits.

Although the company is still in the initial trial stage and can only process a few tons of fecal sludge and produce only tens of kilograms of plastic raw materials every day, the company has won awards such as the "Hunting Goddess Project" to encourage innovation in the field of water resources and the "Water Resources Innovation Leadership" in 2010, and has received certain investments.

People have reason to hope that this technology can be widely adopted and used, and that such environmentally friendly business ideas will emerge in an endless stream, proving that environmental protection and efficiency are not necessarily contradictory. Through intelligent innovation, environmental protection and efficiency can also be perfectly unified.

Types

1. High-pressure polyethylene plastic bags

2. Low-pressure polyethylene plastic bags

3. Polypropylene plastic bags

4. Polyvinyl chloride plastic bags

5. Composite plastic bags Types of plastic bags: Plastic bag materials: HDPE plastic bags, LDPE plastic bags, EVA plastic bags, CPE plastic bags, PPE plastic bags, OPP plastic bags, PP plastic bags, PVC plastic bags, etc.

Hazards

Plastic bags do bring convenience to people's lives, but this temporary convenience brings long-term harm.

Plastic bags have a low recycling value. In addition to being scattered in urban streets, tourist areas, water bodies, and on both sides of roads and railways during use, they also have potential hazards. It is not easy to be degraded by natural microorganisms and will not be separated for a long time in the natural environment. This means that if waste plastic garbage is not recycled, it will become pollutants in the environment and will continue to accumulate, which will cause great harm to the environment.

Plastic Industry Video