First Financial: "Plastic Limit Order" Promotes Huge Industry Dividend

The successive upgrades of the "plastic restriction order" will change the consumption format of disposable products, bring an ecological green stream to the market, and the degradable plastics industry will be surging.

At the beginning of this year, the National Development and Reform Commission and the Ministry of Ecology and Environment announced the "Opinions on Further Strengthening the Control of Plastic Pollution" (hereinafter referred to as the "Opinions"), proposing to develop and promote performance standards, green environmental protection, and economy. Applicable plastic products and alternative products. It is clear that by the end of 2020, China will take the lead in banning and restricting the production, sale and use of some plastic products in some areas and fields.

More than half a year has passed. Recently, nine departments including the National Development and Reform Commission have jointly issued the "Notice on Solidly Promoting Plastic Pollution Control" (hereinafter referred to as the "Notice"). The Notice makes it clear that the policy boundaries and implementation requirements for banning non-degradable plastic bags, disposable plastic tableware, disposable plastic straws and other disposable plastic products will be defined in accordance with the detailed standards for the management of prohibitions and restrictions.

It is understood that the current growth rate of biodegradable plastics production enterprises is obvious. Take Hainan as an example. As of July this year, 46 fully biodegradable plastic products manufacturers have registered. But in the crowd, the most important thing is to see the market, "plastic limit order" in the end what is the limit? What is degradable plastics? To this end, the first financial reporter interviewed the China Plastics Processing Industry Association Degradable Plastics Professional Committee Secretary-General, Beijing Technology and Business University School of Chemistry and Materials Engineering Dean Professor Weng Yunxuan.

First Finance and Economics: The hottest word in the plastic industry now is“Degradable”Can all degradable plastics be degraded to be environmentally harmless?

weng yunxuan:The degradable plastics mentioned in the "Opinions" or "Notice" refer to the fact that such materials can be completely degraded under the corresponding environmental conditions when they enter the garbage disposal link after being discarded, and are harmless to the environment.

Degradable plastics refer to plastics that are degraded by microorganisms existing in nature in nature such as soil, sand, freshwater environment, seawater environment, and specific conditions such as composting conditions or anaerobic digestion conditions, and finally completely degraded into mineralized inorganic salts of carbon dioxide (CO2) or/and methane (CH4), water (H2O) and its contained elements, as well as new biomass (such as microbial dead bodies, etc.).

It should be noted that every biodegradable material, including paper, requires certain environmental conditions for its degradation. If it does not have degradation conditions, especially microbial living conditions, its degradation will be very slow; at the same time, not every biodegradable material can be rapidly degraded under any environmental conditions. Therefore, the treatment of biodegradable materials should be based on its environmental conditions, combined with the structure of the material itself to determine whether it is a biodegradable material.

How to judge whether a material is biodegradable, a series of testing method standards have been issued internationally and in China. Since degradation is related to environmental conditions, degradable materials should clearly identify the environment in which they can be completely degraded on the product, and clarify the production standards, materials, ingredients and other information on which they are based.

The use of degradable materials does not mean that consumers can discard such products at will. Such products should be classified and recycled like traditional plastic products, and recycled and reused according to appropriate disposal methods (including physical recycling, chemical recycling and biological recycling, such as composting, etc.).

As a result of disposable products in the use, recycling and waste disposal process, it is inevitable that a small part from the closed waste disposal system is inadvertently leaked into the environment, the use of completely degradable materials, to a certain extent, can also be used as a preventive measure.

First Financial: What are the main degradable plastics?

weng yunxuan:Degradable materials include biodegradable natural polymer materials, such as cellulose, starch, paper, etc., as well as biodegradable plastics obtained by biosynthesis or chemical synthesis.

These materials can be degraded by composting. If a material such as paper, plastic, etc. is claimed to have composting ability, it must be stated that the material can be biologically decomposed and disintegrated in the composting system, and the compost must meet relevant quality standards, including low heavy metal content, no biological toxicity, and no obvious distinguishable Residues, etc.

Composting methods generally include industrial composting and yard composting. Industrial composting refers to the process of microbial aerobic medium or high temperature degradation of solid and semi-solid organic substances under controlled conditions to produce stable humus. The general cycle is 180 days, but with the change of aerobic composting technology, the shortest time is 30 days or even shorter.

Courtyard composting refers to aerobic composting mainly using household kitchen waste or garden waste. The time of courtyard composting is longer than that of industrial composting, but generally the longest is not more than one year.

It should be noted that it is not to say that degradable plastics can only be degraded by composting. Completely degradable plastics can also be degraded under other conditions, such as soil and sea water in the natural environment, but the speed of degradation is related to the chemical structure of plastics, the formula of products and the degradation environment.

According to the existing experiments and literature reports, PHA, PBAT, PCL, PBS and other materials are relatively easy to biodegrade under the conditions of seawater, soil and compost, and can be completely degraded within 2 to 6 months under the conditions of normal temperature, temperature and humidity. PLA is relatively easy to biodegrade under composting conditions, but the degradation cycle or speed is relatively slow under seawater and soil conditions.

PBAT, PHA, PCL, PBS, etc. can be completely degraded under normal climatic conditions, buried in soil for 5 months and sufficient humidity, and will not affect plants. The degradation rate of PLA materials is relatively slow and takes a long time, but after blending with PBAT or PBS materials, it can be completely degraded within half a year or so from the experimental results.

PHA and PBAT materials can be completely degraded in about 30 to 60 days under simulated seawater at 25 ℃ ± 3 ℃.

Everyone is particularly concerned about whether the degraded products of biodegradable plastics will cause secondary harm to the environment, so the degradation performance of biodegradable plastics requires an increase in the index of heavy metal content; ecological toxicity tests have been carried out on the composted compost of compostable plastics, including phytotoxicity tests, earthworm toxicity tests, etc.; biodegradable plastic films for soil, in addition to the regulations on degradation performance and heavy metal content, the new international standards also provide for ecotoxicity, etc.

Therefore, from the current point of view, biodegradable plastics that meet the requirements of the standard will not cause secondary harm to the environment after degradation.

In addition, the degradable plastic of the polymer containing benzene rings in the main chain is relatively stable. Many people will think that biodegradable plastics containing benzene rings can not be degraded by microorganisms, but because of the particularity of the chemical structure of biodegradable aromatic polymers, there are also microorganisms that can degrade benzene rings in nature, so it can also be degraded by microorganisms, and the toxicity of the degraded products will not cause harm to the environment.

CBN: Can biodegradable plastics be recycled? How to recycle?Will biodegradable plastics affect general plastic recycling?

weng yunxuan:Now the public may have several misunderstandings about degradable plastics.

First of all, some consumers will mistakenly believe that biodegradable plastics will degrade during use or in the air, but they will not. Because biodegradable plastics need to be in the temperature, humidity and microorganisms and other conditions suitable for microbial degradation, so in the daily use or storage period will not be biodegradable.

Secondly, some consumers also believe that biodegradation occurs in any environment, which is not the case. Biodegradable plastics have different degradation behaviors under different conditions because of different varieties and different chemical structures. In addition, degradation also requires certain external environmental conditions. At present, most biodegradable plastics will degrade in soil, sea water, compost and other environments under suitable conditions of temperature and humidity.

Therefore, it is suggested that biodegradable plastics, like traditional plastics, can be recycled physically and recycled first after disposal, and biological or chemical recycling is recommended for those that are not easy to recycle or difficult to recycle.

Biodegradable plastics are actually a special variety of plastics. Their recycling and reuse are the same as traditional plastics. They can be physically recycled and reused, that is, molten recycling and reprocessing. But because it has the characteristics of biodegradation, so more than the traditional plastic can be biological recycling ways (such as composting disposal), in the application of plastic film can no longer be recycled.

In addition, the chemical structure of biodegradable plastics is mainly ester bond, which is easy to degrade by alkali or acid or alcohol, so that it can be chemically recycled compared with traditional plastics, and the material can be recycled through the use of monomer recovery methods.

At present, more than 160 kinds of traditional plastics are commonly used. Biodegradable plastics, as one of them, are currently in small quantities. After entering the recycling system, even if there is no compost biological recovery or chemical recovery, it will not affect the recovery of traditional plastics. The complexity of the traditional plastic system will not make a big difference because of many kinds of degradable plastics.

It is possible for individual recycling systems, such as PET bottle recycling systems, to increase the difficulty of PLA materials, but PET bottle recycling systems will also bring difficulties due to the use of traditional plastic PBT, PEN and other new types of non-degradable polyester bottles. In the modern sorting system, through the infrared sorting method, it is completely possible to achieve separate recycling. Therefore, this problem is only a subjective view that some people have not considered the technical improvement of the original recycling system.

CBN: What are the roles of biodegradable plastics in waste sorting and recycling? What else can the waste sorting and disposal system do to make the degradation of biodegradable plastics more fully reflected?

weng yunxuan:From the point of view of its design and use, in the case of biochemical disposal of disposable products and their use when mixed with organic waste, or in the case of difficult to recycle after the use of plastic film products, the use of biodegradable plastics, its biodegradation function can be reflected more fully.

At the same time, even in Europe and the United States and other developed countries in the garbage classification and disposal has been very standardized, there will always be a part of the plastic packaging will be inadvertently or intentionally released into the natural environment, if this part of the products can be replaced by biodegradable plastics, then can also reduce the risk of environmental pollution.

Therefore, the use of biodegradable plastics can also be considered as a preventive measure to avoid environmental pollution after plastic waste is unintentionally released outside the closed waste system.

In addition, with the improvement of China's garbage classification and disposal system, through the adjustment of the formula of biodegradable plastic garbage bags, it can solve the personal hygiene distress caused by the need to take the initiative to break the bags when throwing kitchen waste.

Some reports mention that biodegradable plastics produce secondary hazards such as dioxins when incinerated compared to traditional plastics. But in fact, biodegradable plastics are a kind of traditional plastics, and there is no chlorine element in its polymer structure. Dioxins will not be produced during incineration. Even traditional plastics are mainly polyethylene materials like common shopping bags. Its molecular chain does not contain chlorine element, and even if incineration does not produce dioxins. In addition, the polyester structure of biodegradable plastics determines that compared with traditional plastics such as polyethylene, the organic carbon content on the main chain is lower, and it is easier to burn fully when incinerated.

In addition, some people worry that biodegradable plastics will release more harmful gases when they are buried in landfills, but most modern landfills currently use some devices that can collect biogas for energy recovery during landfills. The solid content of plastics in landfills is less than 7%, and the current amount of biodegradable plastics is less than 1% of traditional plastics. There is no basis for speculating that landfills will be more harmful.