Carbon dioxide emission reduction, plastics should be biodegraded as soon as possible, these two points are environmental hotspots that people pay attention to. Wouldn't it be great if there was a technology that could achieve both goals at the same time!
In fact, turning carbon dioxide into a degradable plastic is no longer a dream.
结构 Structurally, carbon dioxide can be regarded as the anhydride of carbonic acid and has unsaturated bonds. Therefore, in the presence of a suitable catalyst, carbon dioxide has the possibility of synthesizing polymer materials with other monomers.
However, although carbon dioxide can be reacted with dozens of compounds to prepare a variety of copolymers, due to the relatively low activity and selectivity of the catalyst, coupled with the temperature resistance and mechanical properties of the obtained polymer, it is difficult to industrialize it with existing ones. Products are comparable, and most polymers stay at the level of curiosity in the laboratory.
So far, only copolymers of carbon dioxide and epoxides, especially copolymers of carbon dioxide and propylene oxide (PPC), have good biodegradability, relatively low cost, and use carbon dioxide in large quantities. More than 40% by weight, it is highly valued.
The advantage of PPC is that it can be completely composted and degraded within 6 months, while traditional plastics usually do not have biodegradability. At the same time, PPC plastic film has better oxygen barrier performance than nylon and PET ester).
Since the Japanese scientist Shoji Inoue realized the copolymerization of carbon dioxide and epoxide in 1969, people have developed various catalyst systems to synthesize PPC.
差距 The gap in thermodynamic performance is the biggest resistance to development
But at present, the industrialization of PPC is still in its infancy. What hinders its industrialization?
For industrial products, polymer synthesis costs and production cycles are critical. The high cost of catalysts, long polymerization cycles, and low polymer properties have traditionally limited the industrial production of carbon dioxide copolymers.
However, careful analysis shows that cost is not the main problem that carbon dioxide-based plastics currently face. In terms of the rare earth ternary catalyst technology currently developed by the Changchun Institute of Applied Chemistry of the Chinese Academy of Sciences, the cost of the catalyst per ton of carbon dioxide plastic is less than 1,500 yuan, and the comprehensive cost is only 20% to 30% higher than that of polyethylene. a lot of.
Compared with other biodegradable plastics, PPC contains more than 40% carbon dioxide, which is the lowest cost type of biodegradable materials, which helps solve the cost bottlenecks that restrict the development of biodegradable plastics for a long time. Due to the small scale of the existing PPC production equipment, it has not yet produced scale benefits, resulting in its price being at a relatively high level compared with general-purpose plastics. With the improvement of process packages and the large-scale application of new high-efficiency and high-selectivity catalysts, the scale benefits of large-scale production units will help further reduce costs. There are reasons to believe that even when compared with materials such as polyolefins, PPC will be competitive in terms of cost performance in the future.
The real core problem is that compared with polyolefins, carbon dioxide plastics have poor overall thermodynamic properties and cannot be used alone. It is difficult to really open a large-scale market based on biodegradability alone.
PPC plastics have inherent defects in mechanics and temperature resistance. They are amorphous materials, they cannot be crystallized, and their glass transition temperature is around 35 ° C. Therefore, they lose their strength quickly when the temperature is high (40 ° C) and the temperature is lower. (Below 20 ° C) is very brittle, and its use temperature range is very narrow, only between 20 ° C and 40 ° C.
This is far from the traditional plastic polyethylene or polypropylene. Because although the glass transition temperature of traditional plastics is low, much lower than 0 ° C, due to its excellent crystallization properties, its use temperature range is wide, from -20 ° C to 80 ° C. PPC is also different from amorphous polystyrene or polyvinyl chloride with high glass transition temperature. The latter two can maintain mechanical properties over a wide temperature range (-20 ° C to 100 ° C) through plasticization and toughening. This difference in thermodynamic properties is the main reason why it is difficult for PPC to quickly open the market.
Market size to be developed
In foreign countries, only Empower materials of the United States currently sells 100 kilograms of carbon dioxide plastic. It is mainly used as a sacrificial adhesive for ceramics and electronics. It takes advantage of the low thermal decomposition temperature of carbon dioxide plastic (less than 300 ° C) to reduce Energy consumption of electronic ceramic products.
In addition, from 2005, companies such as Novomer, SK Group in South Korea, BASF in Germany, and Mitsubishi Chemical in Japan all started to build industrial production lines for carbon dioxide plastics, but there are no reports of product sales.
Although the market for carbon dioxide-based plastics has not yet been opened, it is believed that with the further breakthrough of the comprehensive thermodynamic properties of plastics and the further reduction of costs, a larger market is just around the corner.
The Yingying Institute has worked closely with domestic and foreign companies and research institutions. Through nearly four years of efforts, it has recently made important progress in the field of carbon dioxide plastic films and medical packaging. Among them, carbon dioxide plastic film has passed the comprehensive demonstration of the United States Biodegradable Plastics Research (BPI), and has made breakthroughs in the improvement of biodegradability and thermodynamic properties. It can be used for a long time at -15 ° C to 60 ° C. The impact resistance of the film exceeds 120 grams, impact resistance and tear resistance is equivalent to polyethylene, fully meeting the requirements for use as a general packaging film, and has developed the 10,000-ton film market in the United States and Europe.
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