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Used as a polyurethane foaming agent
Dimethyl ether has extremely low toxicity and can be degraded into carbon dioxide and water in about 10 days in the atmosphere. ODP (zero ozone depletion potential) is zero, so it will not cause environmental pollution and affect the ozone layer. At the same time, dimethyl ether has high solubility in polar and non-polar organic substances, is easily soluble in water, and can be mixed with most solvents; it is also mixed with a small amount of high-boiling HFCs (hydrofluorocarbons) and high-boiling solvents. Can get a liquid, non-flammable mixture at room temperature. Jia Runli believes that these characteristics of dimethyl ether can not only ensure the safety of polyurethane foam production, but also have wide applicability to current polyurethane foam production equipment, and the mutual solubility with polyether polyol is beneficial to increase the foaming efficiency and size of polyurethane foam. stability. In addition, dimethyl ether is also an ideal alternative to CFC (chlorofluorocarbon)-11. These characteristics make dimethyl ether theoretically possible as a polyurethane foaming agent. At present, the price of dimethyl ether in our country is more than 4,000 yuan per ton, and the production capacity has reached 4 million tons. However, the market price of cyclopentane and iso-pentane-based blowing agents that are currently used are between 15,000 and 18,000 yuan per ton. About dimethyl ether is therefore economically feasible as a polyurethane foaming agent.
Jia Runli said that some domestic companies and foreign companies are now using water as a polyurethane foaming agent, but other auxiliaries are needed, and the comprehensive cost is as high as 17,000 to 18,000 yuan per ton. The miscibility of dimethyl ether with water makes it very easy to apply to the all-water foaming route, which helps to improve the defect of low strength, poor stability, and poor thermal insulation of the all-water-blown polyurethane foam, and can reduce the amount of polyisocyanate used. In addition, dimethyl ether can be used to reduce the viscosity of the system and increase the mixing of the components in the system. Although the boiling point of dimethyl ether is relatively low, the dimethyl ether/water azeotropic point is significantly increased after being miscible with water. Therefore, the current equipment can still be used in various foaming processes of water foaming systems.
Safer than alkane blowing agents
Jia Runli pointed out that the main reasons for the widespread use of cyclopentane and iso-pentane foaming agents in alkane-based foaming agents in polyurethane foaming are their zero ODP value, high boiling point, small greenhouse effect, and no Poison, liquid at room temperature and other characteristics. However, it also has flammable, volatile and other characteristics, so that when it is used as a foaming agent, it must be a major transformation of the existing measurement, storage, foaming equipment. In addition, the solubility of alkane-based foaming agents in polyether polyols is poor, and it is necessary to use modified polyols and special auxiliaries to limit the use of cyclopentane and cyclopentane-based foaming agents. Compared with it, dimethyl ether also has the advantages of zero ODP value, little greenhouse effect, no toxicity, rich resources, and low price.
Dimethyl ether is gaseous at room temperature, but if mixed with a small amount of high-boiling alkane, a liquid mixture at room temperature can be obtained, and its explosion limit is double that of pentane, and the safety is relatively high, with a small amount of HFC or HCFC (including Hydrochlorofluorocarbon (HCFC) mixing can achieve non-combustible effects. In addition, the mutual solubility of dimethyl ether and polyols helps to increase the foaming efficiency and dimensional stability of polyurethane foams.
Lower cost than fluorine-containing foaming agent
According to reports, fluorine-containing foaming agents include HCFC, HFC, PFA (perfluoroalkane) and HFE (fluoroether). Compared with these four kinds of fluorine-containing foaming agents, DME has shorter lifespan in the atmosphere than any of them, and the lowest cost. If used alone, the foaming process is equivalent to gaseous HFC, but dimethyl ether is The high solubility of polyols makes its foam performance better than that of HFC foaming systems; if it is mixed with a small amount of high-boiling solvents and high-boiling HFCs, it can completely reach the state of non-combustible and liquid at room temperature and can adapt to high boiling points. The HFC foaming system now uses equipment and processes.
At present, dimethyl ether, as a clean fuel that can replace diesel resources, has been widely promoted and applied. At the same time, dimethyl ether is also expected to be used for many unique applications such as aerosols, aerosols, and blowing agents as an emerging basic chemical raw material with easy compression, condensation, and vaporization characteristics. “Compared with the currently used cyclopentane and cyclopentane type foaming agents, dimethyl ether has a comparative advantage in foaming polyurethane (PU) foaming agents.†North China University (formerly North China Institute of Technology) Plastics Professor Jia Runli, the director of the institute, came to this conclusion after a comprehensive analysis of the various characteristics of dimethyl ether and current production capacity and prices.