At present, the annual consumption of plastics in China has reached more than 40 million tons, and it is expected that it will continue to grow at an annual rate of at least 8% in the next few years. However, the development of China's plastics industry faces two major issues of increasing energy supply and environmental pollution. Therefore, finding new resources that can replace petroleum, developing environmentally friendly materials, and reducing the generation and emission of pollutants have become one of the urgent tasks for the Chinese plastics industry. At the same time, the promotion of economic restructuring and changes in economic growth patterns through energy conservation and emission reduction are inevitable choices for China’s economic development. In this context, the development of biodegradable plastics is worth looking forward to.
Biodegradable plastics are considered to be the materials with the least environmental load in the aspects of raw material utilization, product manufacturing, use or recycling, etc., with low resource and energy consumption, low emissions, high recycling rate, and no pollution to the environment and the environment. The features are conducive to reducing the environmental pollution caused by petroleum-based plastic products and reliance on non-renewable petroleum resources. The reduction of pollutant emissions at the lowest cost can be realized, and the utilization of resources can be maximized. This is an important way to achieve energy conservation and emission reduction at present. one. Biodegradable plastics have become a necessity instead of ordinary plastics.
The biodegradable plastics that have been industrialized so far are mainly starch plastics, polylactic acid and so on. Its representative products are starch-based biodegradable plastics produced by Italy's Noramont Co., Ltd. The production capacity in 2003 reached 120,000 tons; the polylactic acid produced by the United States Nature Works Polymer Company has an annual production capacity of 140,000 tons. The production capacity of biodegradable plastics in China is relatively small, but it has developed rapidly in recent years. At present, carbon dioxide (CO2) plastics have been successfully developed and put into production. New biodegradable plastics such as genetically modified bio-plastics have always attracted the attention of researchers in various countries.
Ordinary plastics such as polyethylene, polypropylene and other synthetic resins use non-renewable petroleum resources as raw materials, and the production process consumes a lot of energy. Take the synthesis of polyethylene as an example. At present, developed countries generally adopt the tubular method for production. The material consumption and energy consumption per ton of polyethylene are: 1.008 tons of ethylene, 800 kWh of electricity, 1 ton of steam, 120 cubic meters of cooling water, and nitrogen. 5 cubic meters. Compared with foreign countries, there is still a big gap between domestic polyethylene production and higher material consumption and energy consumption. Biodegradable plastics are mainly renewable raw materials, originating from crops, and are energy-saving and environmentally friendly raw materials. In China, where 40 million tons of plastics are consumed annually, if one-third of them are replaced with starch-degradable plastics, the consumption of crude oil can be reduced by at least 10 million tons. According to the above calculation of polyethylene synthesis energy consumption, it can save 8 billion kwh. According to the conversion index values ​​of the total national energy consumption and total CO2 emission estimates, 0.4 kilograms of standard coal per kilowatt hour of electricity production is calculated, and 1 kilogram of CO2 is discharged. Then, the country’s total annual energy savings can reach 3.2 million tons of standard coal. Corresponding reductions in CO2 emissions of 8 million tons will also be achieved, in addition to significant savings in water resources. The use of biodegradable plastics in place of general-purpose plastics saves only a considerable amount of energy. This shows that bio-degradable plastics have great potential for energy conservation.
In addition, biodegradable plastics usually have lower processing temperatures than ordinary plastics. Taking starch-based degradable plastics as an example, due to the rapid degradation at higher temperatures, the processing temperature of starch-based degradable plastics is usually below 150°C, while the processing temperature of polyolefin plastics is usually around 200°C. According to this calculation, the processing energy consumption of biodegradable plastics with the same output is significantly lower than that of ordinary plastics.
Biodegradable plastics can partially or completely replace general-purpose plastics to achieve the goal of reducing the amount of synthetic resins and saving petroleum resources, thereby reducing the dependence of plastics on petroleum resources. At present, the annual global consumption of plastics amounts to 240 million tons, an increase of 4% year-on-year. If one-third of them are replaced with biodegradable plastics, the economic benefits of saved oil resources and consequent reduction in pollution emissions are inestimable. Therefore, the biodegradable plastic's substitution effect on oil can largely protect China's energy security while protecting the environment.
Biodegradable plastics not only have energy-saving and emission-reducing effects in the production process, but also have environmentally friendly features during use. The synthesis of common polyolefin plastics will emit a large amount of CO2 and other exhaust gases and pollutants, while the use of plastic products in large quantities, especially agricultural films and packaging materials has caused increasingly serious white pollution. Biodegradable plastic is not the case. Its source of raw materials is renewable crops. During the growth process, crops can absorb CO2 and release oxygen through photosynthesis. The product waste can be completely degraded into water and CO2 under the condition of buried compost, without pollutants. produce. The new type of degradable plastic, CO2 plastic, which has been successfully developed in China, is based on industrial waste CO2 and hydrocarbon as raw materials. The content of CO2 is 31%~50%. Compared with ordinary plastics, CO2 plastics not only use industrial waste CO2 to turn waste into treasure, effectively reducing the greenhouse effect, but also greatly reducing the consumption of hydrocarbons and the upstream raw materials of petroleum. In recent years, great progress has been made in the research of producing biodegradable plastics using transgenic plants. With the development of recombinant DNA technology, the commercialization of biodegradable plastics using transgenic plants in the future will certainly promote the wide application of biodegradable plastics, further saving oil resources and reducing environmental pressure. Therefore, the process of expanding the scale of the biodegradable plastics industry is actually the process of CO2 emission reduction. It can gradually eliminate the two major problems that have plagued the world's greenhouse effect and white pollution for many years, and promote the harmonious development of humanity, economy and the environment.
The National Development and Reform Commission promulgated the “Guidelines for Priority Areas for High-tech Industrialization in Current Development†for the year 2007, which identified 130 key areas for high-tech industrialization, with environmentally friendly materials among them. The "Eleventh Five-Year Plan" for the development of bio-industries also pointed out that it is necessary to vigorously develop bio-based products and achieve partial replacement of fossil raw materials. Therefore, we have reason to believe that the biodegradable plastics industry is ushering in great opportunities for development.
Biodegradable plastics are considered to be the materials with the least environmental load in the aspects of raw material utilization, product manufacturing, use or recycling, etc., with low resource and energy consumption, low emissions, high recycling rate, and no pollution to the environment and the environment. The features are conducive to reducing the environmental pollution caused by petroleum-based plastic products and reliance on non-renewable petroleum resources. The reduction of pollutant emissions at the lowest cost can be realized, and the utilization of resources can be maximized. This is an important way to achieve energy conservation and emission reduction at present. one. Biodegradable plastics have become a necessity instead of ordinary plastics.
The biodegradable plastics that have been industrialized so far are mainly starch plastics, polylactic acid and so on. Its representative products are starch-based biodegradable plastics produced by Italy's Noramont Co., Ltd. The production capacity in 2003 reached 120,000 tons; the polylactic acid produced by the United States Nature Works Polymer Company has an annual production capacity of 140,000 tons. The production capacity of biodegradable plastics in China is relatively small, but it has developed rapidly in recent years. At present, carbon dioxide (CO2) plastics have been successfully developed and put into production. New biodegradable plastics such as genetically modified bio-plastics have always attracted the attention of researchers in various countries.
Ordinary plastics such as polyethylene, polypropylene and other synthetic resins use non-renewable petroleum resources as raw materials, and the production process consumes a lot of energy. Take the synthesis of polyethylene as an example. At present, developed countries generally adopt the tubular method for production. The material consumption and energy consumption per ton of polyethylene are: 1.008 tons of ethylene, 800 kWh of electricity, 1 ton of steam, 120 cubic meters of cooling water, and nitrogen. 5 cubic meters. Compared with foreign countries, there is still a big gap between domestic polyethylene production and higher material consumption and energy consumption. Biodegradable plastics are mainly renewable raw materials, originating from crops, and are energy-saving and environmentally friendly raw materials. In China, where 40 million tons of plastics are consumed annually, if one-third of them are replaced with starch-degradable plastics, the consumption of crude oil can be reduced by at least 10 million tons. According to the above calculation of polyethylene synthesis energy consumption, it can save 8 billion kwh. According to the conversion index values ​​of the total national energy consumption and total CO2 emission estimates, 0.4 kilograms of standard coal per kilowatt hour of electricity production is calculated, and 1 kilogram of CO2 is discharged. Then, the country’s total annual energy savings can reach 3.2 million tons of standard coal. Corresponding reductions in CO2 emissions of 8 million tons will also be achieved, in addition to significant savings in water resources. The use of biodegradable plastics in place of general-purpose plastics saves only a considerable amount of energy. This shows that bio-degradable plastics have great potential for energy conservation.
In addition, biodegradable plastics usually have lower processing temperatures than ordinary plastics. Taking starch-based degradable plastics as an example, due to the rapid degradation at higher temperatures, the processing temperature of starch-based degradable plastics is usually below 150°C, while the processing temperature of polyolefin plastics is usually around 200°C. According to this calculation, the processing energy consumption of biodegradable plastics with the same output is significantly lower than that of ordinary plastics.
Biodegradable plastics can partially or completely replace general-purpose plastics to achieve the goal of reducing the amount of synthetic resins and saving petroleum resources, thereby reducing the dependence of plastics on petroleum resources. At present, the annual global consumption of plastics amounts to 240 million tons, an increase of 4% year-on-year. If one-third of them are replaced with biodegradable plastics, the economic benefits of saved oil resources and consequent reduction in pollution emissions are inestimable. Therefore, the biodegradable plastic's substitution effect on oil can largely protect China's energy security while protecting the environment.
Biodegradable plastics not only have energy-saving and emission-reducing effects in the production process, but also have environmentally friendly features during use. The synthesis of common polyolefin plastics will emit a large amount of CO2 and other exhaust gases and pollutants, while the use of plastic products in large quantities, especially agricultural films and packaging materials has caused increasingly serious white pollution. Biodegradable plastic is not the case. Its source of raw materials is renewable crops. During the growth process, crops can absorb CO2 and release oxygen through photosynthesis. The product waste can be completely degraded into water and CO2 under the condition of buried compost, without pollutants. produce. The new type of degradable plastic, CO2 plastic, which has been successfully developed in China, is based on industrial waste CO2 and hydrocarbon as raw materials. The content of CO2 is 31%~50%. Compared with ordinary plastics, CO2 plastics not only use industrial waste CO2 to turn waste into treasure, effectively reducing the greenhouse effect, but also greatly reducing the consumption of hydrocarbons and the upstream raw materials of petroleum. In recent years, great progress has been made in the research of producing biodegradable plastics using transgenic plants. With the development of recombinant DNA technology, the commercialization of biodegradable plastics using transgenic plants in the future will certainly promote the wide application of biodegradable plastics, further saving oil resources and reducing environmental pressure. Therefore, the process of expanding the scale of the biodegradable plastics industry is actually the process of CO2 emission reduction. It can gradually eliminate the two major problems that have plagued the world's greenhouse effect and white pollution for many years, and promote the harmonious development of humanity, economy and the environment.
The National Development and Reform Commission promulgated the “Guidelines for Priority Areas for High-tech Industrialization in Current Development†for the year 2007, which identified 130 key areas for high-tech industrialization, with environmentally friendly materials among them. The "Eleventh Five-Year Plan" for the development of bio-industries also pointed out that it is necessary to vigorously develop bio-based products and achieve partial replacement of fossil raw materials. Therefore, we have reason to believe that the biodegradable plastics industry is ushering in great opportunities for development.
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