Progress in Research and Development of Cleaning Solvent

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At present, CFC-113 (trichlorotrifluoroethane), 1,1, 1-trichloroethane, carbon tetrachloride and other ODS substances are widely used in the cleaning industryCleaning agent. These ODS cleaning agents seriously damage the atmospheric ozone layer, is increasingly serious impact on the earth's environment and human quality of life, is listed as a prohibited product. According to the requirements of the Montreal Protocol on Substances that Deplete the Ozone Layer, developed countries stopped producing and using ODS substances in 1996, developing countries will completely phase out ODS substances in 2010, and developed countries are not allowed to import products cleaned with ODS substances. Therefore, non-ODSEnvironmental cleaning agentbecome a hot research at home and abroad.
With the development of environmentally friendly cleaning agents, some new alternatives have been developed and are expected to replace CFC-113 and trichloroethane in different cleaning fields. Hydrofluoroether cleaning agent (HFE) Hydrofluoroether is non-flammable and does not destroy the ozone layer, in many areas can replace CFC-113 and HCFC-141b(CH3Cl2CF). The United States 3M company has introduced HFE-7100(C4F9OCH3), HFE-71DA, HFE-71DE and a series of hydrofluoroether cleaning agent. These cleaning agents have an ODP (ozone layer depletion coefficient) value of zero and a low GWP (greenhouse effect coefficient) value. HFE-7100 has high relative density, low surface tension, good wettability, and strong penetration ability. It is suitable for vapor phase rinsing and vapor phase rapid drying, but it has low toxicity. The American Industrial Hygiene Association has determined its working environment exposure limit (WEEL) to be 750mg/L.

Brominated hydrocarbon cleaning agent

The U.S. Environmental Protection Agency (EPA) issued a notice in June 2003 listing nPB (1-bromopropane, C3H7Br) as an "acceptable replacement agent under appropriate conditions" on ODS ". nPB has a lower ODP value, and its solubility is 4 times that of traditional chlorocarbon solvents, so its consumption is greatly reduced, reducing the amount of waste gas, thereby reducing the pressure of environmental damage. Due to the poor chemical stability of nPB, stabilizers or inhibitors must be added when used. In order to achieve the best cleaning effect, nPB in most cases need to be mixed with other cleaning solvents. The nPB product produced by Petroferm Corporation of the United States, whose trade name is LENIUMGS, is an azeotrope of n-bromopropane and isopropanol, which is used for cleaning electronic products and also for cleaning relays in aerospace and nuclear industries that require high reliability. For example, a spray cleaner composed of about 50%(W%) nPB and about 50%(W%) tetrafluoroethane (as a propellant) is suitable for circuit board and junction box cleaning. As a substitute for ODS cleaning agent, nPB is active in the market. Its solubility is similar to that of trichloroethane, but it has a very low ODP value, especially in terms of price. The use of such cleaning agents has been approved by the United States Environmental Protection Agency and has been widely used in the electronics industry, aviation industry and automobile manufacturing industry.
Hydrofluorocarbon cleaner (HFC)

(1)1,1,1,3, 3-pentafluoropropane (HFC-245fa). HFC-245fa can be used to clean printed circuit boards, magnetic heads, relays, various communication medical equipment and jewelry. The physical properties of the HFC-245fa are similar to HCFC-141b(CH3Cl2CF), the matching is better than HCFC-141b, and it has the characteristics of not destroying the ozone layer and being non-flammable. Mixtures of HFC-245fa, alcohols and the like can increase the cleaning ability. The azeotrope-like mixture of HFC-245fa with 2-chloropropane and dichloroethylene is an ideal substitute for CFCs and HCFCs cleaning agents.
(2)1,1,1,3, 3-pentafluorobutane (HFC-365mfc). In the field of precision cleaning, HFC-365mfc can be used to replace CFC-113 and HCFC-141b. The outstanding advantage of HFC-365mfc is that the ODP value is zero; its disadvantage is that it has a certain flammability, but when it is mixed with a small amount of HFC-245fc and other substances, it can form a non-flashpoint, non-flammable mixture.

(3)1,1,1,2,3,4,4,5,5,5-decafluoropentane (HFC-4310mee). HFC-4310mee has the advantages of non-destructive ozone layer, low surface tension, good wetting permeability, stable chemical properties and non-flammable, and can replace CFC-113 and HCFCs as cleaning solvents, in addition to flux and heat transfer media. HFC-4310mee with most esters, ketones, ethers, alcohols (such as methanol, ethanol, isopropanol) completely miscible. And lower alkanes such as hexane, heptane is also very soluble. For example, azeotropic mixtures or azeotrope-like mixtures of HFC-4310mee with trans-1, 2-dichloroethylene, cis-1, 2-dichloroethylene or 1,1-dichloroethane can be used as cleaning agents. At present, HFC cleaning agent has a series of products available. Such as the United States DuPont production of HFC-4310 series cleaning agent, its trade name is VERTREL, can be used for electronics, aviation, optical disk drive, military, medical and other fields of cleaning.
Green chemistry is an important part of the sustainable development strategy of economy and society, and it is also an important trend of the development of cleaning technology and cleaning agents in the 21st century. With the development of economy and society, people will pay more attention to environmental protection, and green chemistry will also get unprecedented development. In the cleaning industry, with the development of ODS substances, there will be more and more environmentally friendly cleaning agents, green cleaning technology will be more mature, and the application field will be broader.