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Alternatives to ODSs – Properties and Application Prospects of Hydrocarbon Cleaners (Internal Document) Tianjin Promi Chemical Co., Ltd. Among the cleaners used in the industrial cleaning sector, ODSs (substances that destroy the ozone layer) account for a large proportion; particularly in precision cleaning, trifluorotrichloroethane (CFC-113) and 1,1,1-trichloroethane are highly popular as they are considered to be the “best cleaners”. As concern and emphasis on environmental protection and human health grow, finding new alternatives to replace ODS cleaning agents has become an urgent task. To this end, **departments, scientists, and related companies around the world have made significant investments, and various alternative products and technologies have emerged as a result. Considering various aspects such as cost, practicality, safety, and environmental protection, hydrocarbon cleaning agents are a highly promising alternative to ODSs. I. Comparison of three alternative approaches The alternative technologies for ODS cleaning agents can be divided into three types: 1. Modifying the cleaning process using existing cleaning techniques: represented by water washing and semi-water washing. The inevitable trend is the phasing out of halogenated hydrocarbon cleaning agents. Halogenated hydrocarbons are compounds formed when some or all of the hydrogen atoms in hydrocarbon molecules are replaced by halogen atoms (fluorine, chlorine, bromine, iodine). The halogenated hydrocarbon cleaning agents most commonly used in the field of industrial cleaning fall into two categories: chlorinated hydrocarbons and chlorofluorocarbons. These include dichloromethane, trichloromethane (chloroform), 1,1,1-trichloroethane, trichloroethylene, tetrachloroethylene, carbon tetrachloride, and trifluorotrichloroethane (F-113). Halogenated hydrocarbon cleaning agents are widely used due to their strong cleaning power, non-flammability, rapid drying time, and ease of distillation for reuse. According to statistics, in 2000, China used over one million tons of such cleaning agents for industrial cleaning purposes. However, halogenated hydrocarbon cleaning agents pose many hazards to humans, the items being cleaned, and the environment during use: 1. Toxicity: All of the aforementioned solvents, with the exception of F-113 and 1,1,1-trichloroethane, are highly toxic; exposure through the skin, inhalation, or accidental ingestion can lead to poisoning of the liver, kidneys, and blood. Mild cases result in dizziness and vomiting, while severe cases can cause shock or even death. Some solvents can also produce phosgene under sunlight, which is highly toxic and carcinogenic. Therefore, strict requirements are imposed on the locations of use and personnel protection, with the maximum allowable concentration in the air being 10–500 ppm. 2. Corrosion: Since most halogenated hydrocarbon cleaners contain chlorine atoms, they can decompose to produce hydrochloric acid under certain conditions, thereby causing corrosion to equipment and metal components. Most chlorinated hydrocarbon solvents will dissolve, swell, deform, or embrittle plastic and rubber parts, limiting their range of use for cleaning. 3. High evaporation losses: Chlorinated hydrocarbon cleaners have low boiling points (generally between 40–80°C) and are volatile liquids; during transportation, storage, and use, about 40% of the cleaner is lost due to evaporation. 4. Environmental pollution: Chlorinated hydrocarbon solvents cannot degrade naturally, and their release causes severe pollution to air, water bodies, and soil. 5. Destruction of the ozone layer: The volatile gases of F-113, carbon tetrachloride, and 1,1,1-trichloroethane remain in the atmosphere and rise with air currents. In the stratosphere, they are broken down by ultraviolet radiation, releasing chlorine atoms. These chlorine atoms act as catalysts, continuously triggering reactions that damage the ozone layer, thereby reducing its ability to block ultraviolet rays and posing a threat to humans, animals, and plants on Earth. Carbon tetrachloride, trichloromethane, trichloroethylene, and tetrachloroethylene – halogenated hydrocarbon cleaning agents with high toxicity – have long attracted considerable attention. Initially, methods such as the use of gas masks, sealing of cleaning rooms, and sealing of cleaning equipment were employed to reduce their dispersion and limit the scope of contamination. After the superior performance of the F-113 was discovered, few people used such solvents for cleaning anymore. F-113 is a colorless and odorless liquid with good chemical stability; it does not deteriorate when stored at room temperature for long periods of time. It has a strong ability to dissolve mineral oils, but it does not dissolve most metals, plastics, rubbers, or coatings. Additionally, it is non-toxic and non-flammable, making it very safe to use. Also, with a boiling point of 47.6°C, it can dry naturally after cleaning. The F-113 is recognized as the best solvent-based cleaner, and its usage volume ranks first among solvent-based cleaners. However, due to global efforts to protect the ozone layer, the phasing out of the F-113 was an inevitable trend. Under the auspices of the United Nations, countries **signed the Vienna Convention for the Protection of the Ozone Layer and the Montreal Protocol on Substances that Deplete the Ozone Layer**, which clearly specify the responsibilities, goals, methods, and timelines for phasing out ozone-depleting substances. In January 1993, China approved the implementation of its **Plan for the Phased Outward Elimination of Ozone-Depleting Substances in China**. In March 2000, the Executive Committee of the Multilateral Fund under the Montreal Protocol officially approved China’s **Comprehensive Plan for the Elimination of ODS in the Cleaning Industry**. According to the plan, the production and consumption of F-113 used as a cleaning agent will decrease year by year starting from July 2000, and will be completely phased out by January 1, 2006. 1,1,1-Trichloroethane, used as a cleaning agent, was gradually phased out starting in 2000 and completely eliminated by January 1, 2010. The relevant Chinese authorities have implemented restrictions on the production, operation, and consumption of such products, as well as measures to encourage their replacement. Due to the strict restrictions on the F-113 worldwide, various alternative technologies emerged. The main methods are: 1. Water washing and semi-water washing: These have the lowest cost, but they suffer from shortcomings such as poor cleaning efficiency, complex processing procedures, rust formation, residual water stains, and pollution from wastewater discharge, which limits their widespread use. 2. Hydrochlorofluorocarbons (HCFCs-225, -1416): Their properties are similar to those of chlorofluorocarbons; their ozone-destruction potential is **reduced (but not eliminated), yet they are toxic and unsafe for plastic materials. Although such solvents are being promoted in China, their production in other parts of the world will cease after December 31, 2002. 3. Some companies in the United States have begun to research more advanced hydrofluorocarbons and hydrofluoroethers. These substances have excellent properties, but their cost is several times to over a dozen times that of chlorofluorocarbons. The cost issue associated with promoting it in China at present is not acceptable. 4. Hydrocarbon solvents: They have advantages such as strong cleaning power, low cost, good compatibility with materials, non-toxicity, environmental friendliness, and no damage to the ozone layer. The drawbacks of low flash point and slow evaporation are addressed through the use of advanced equipment. In developed countries, especially Japan and Western Europe, they have become the preferred choice over halogenated hydrocarbon solvents. They are also used in China, but mainly by foreign-funded enterprises, which rely on imported solvents. II. Characteristics of HY series cleaners Hydrocarbon solvents are mixtures of straight-chain alkanes, branched alkanes, cycloalkanes, olefins, and aromatic hydrocarbons, which are obtained as different fractions during the distillation of petroleum. The HY series of cleaning agents developed by our company are pure, colorless, and transparent liquids obtained by meeting the requirements of industrial cleaning. For this purpose, narrow-range solvent oils with a boiling range of 150–190°C are selected; advanced processes are then used to remove olefins with poor chemical stability, sulfur-containing compounds that are malodorous, toxic, and corrosive to metals, highly toxic aromatic hydrocarbons, as well as water-soluble acids, bases, mechanical impurities, and water. Organic additives are also incorporated into these products. Therefore, in addition to the general advantages of ordinary solvent oils, the HY series of cleaning agents possess many unique benefits: 1. Excellent cleaning performance – based on the principle of like dissolves like, hydrocarbon solvents have a strong ability to dissolve lubricants, greases, rust inhibitors, etc., and can remove various types of dust and metal shavings from workpieces. Due to its low surface tension and water insolubility, it can drive away the water on the surface of the workpiece, causing it to condense into droplets that fall to the bottom of the cleaning tank. Due to the addition of additives such as oil-soluble surfactants in the HY series of cleaners, it is also capable of removing solder slag and flux from electronic circuit boards, which are difficult to clean with ordinary hydrocarbon solvents, as well as emulsified cutting fluid from machined parts. 2. Low toxicity. The HY series of cleaners are primarily composed of straight-chain and isomeric alkanes, with toxic aromatics and sulfur-containing compounds removed. According to tests conducted by the chemical toxicity testing department, the inhalation toxicity, oral toxicity, and skin contact toxicity of the HY series of cleaners are all essentially non-toxic; they are not carcinogenic substances, so they can be used with confidence. 3. It can volatilize completely without leaving any residue. The HY series of cleaning agents are highly pure refined solvents that can evaporate completely at both room temperature and elevated temperatures, leaving no residue behind. 4. Safe for the materials to be cleaned. The HY series of cleaners does not cause corrosion or rust on metal materials. It has no effect of dissolution, swelling, or embrittlement on most plastics and rubbers, thus allowing for a very wide range of applications. 5. Low evaporation loss. The boiling point of HY series cleaners is above 150°C, resulting in minimal vapor loss during use and storage; therefore, low requirements are placed on the sealing of packaging materials and equipment. 6. Do not damage the environment. The HY series of cleaners can degrade naturally and will break down quickly when buried in soil. The cleaning waste liquid can be incinerated in coal or fuel boilers; the by-products of combustion are mainly CO2 and water, with only a small amount of CO, so it causes no pollution to the air. 7. Does not damage the ozone layer. The HY series of cleaners contain no chloride ions, and their ozone-destruction coefficient is zero. 8. Not flammable. The flash point of the HY series of cleaners is 56°C; it is classified as a flammable substance with a high flash point under China’s fire safety regulations, and it falls into Category 4, Subcategory 2 of petroleum-based substances under Japan’s fire safety laws. It is not easily ignited by an open flame at room temperature, making it relatively safe to use. But after all, it is a flammable material, so it should be kept away from open flames when in use, and necessary fire prevention measures should be taken. 9. Low price. The price of the HY series of cleaners is less than 50% of the price of F-113, 5% of the price of hydrofluorocarbons and hydrofluoroethers, and two-thirds of the price of imported hydrocarbon-based cleaners. Since the density of the HY series cleaners is **lower than that of halogenated hydrocarbon solvents, the amount of HY series cleaner required in a cleaning tank of the same volume is only half that of halogenated hydrocarbon solvents. 10. Suitable for mechanical cleaning. The HY series of cleaning agents have a narrow boiling range, and are dried and distilled for regeneration in specialized cleaning machines. Recently, the HY series of cleaning agents have passed the specification tests and practical tests conducted by two Japanese companies that manufacture vacuum cleaning and drying machines, meeting all the requirements. Like other hydrocarbon solvents, the HY series of cleaners pose difficulties in terms of heating for cleaning, drying after cleaning, and reuse due to their low flash point and high boiling point. However, Japan overcame this bottleneck using vacuum technology by developing vacuum cleaning dryers, which made hydrocarbon solvents the mainstream among cleaning agents. Our company is collaborating with Japanese manufacturers to introduce vacuum cleaning and drying machines to China. When these machines are used in conjunction with the HY series of cleaning agents, they will surely bring about new advancements in industrial cleaning in China. III. Principles and Characteristics of Vacuum Cleaning and Drying Machines. The biggest obstacle to using hydrocarbon solvents in industrial cleaning is their high boiling points and low flash points. High boiling points result in a slow drying speed, and during heating for drying and distillation for regeneration, the temperature must be above the flash point, which poses a fire hazard. A vacuum cleaning and drying machine performs cleaning, drying, and distillation regeneration under vacuum conditions, reducing the boiling point of hydrocarbon solvents to below 80°C, thereby **accelerating** the drying speed as well as the speed of distillation regeneration. At the same time, the low oxygen concentration in a vacuum prevents hydrocarbon solvents from burning. The vacuum cleaning and drying machine introduced by our company also incorporates many advanced technologies, giving it advantages that other cleaning methods cannot match: 1. Strong cleaning capacity: To enhance the cleaning effect, four technologies are used in this vacuum cleaning and drying machine: (1) Ultrasonic vibration. According to the requirements of the object to be cleaned, an ultrasonic generator is installed at the bottom of the cleaning tank, using ultrasonic waves of different powers and wavelengths to cause high-frequency oscillations in the solution. (2) Vacuum cleaning. In a vacuum environment, the air in the blind holes and small gaps of the workpiece is removed, allowing the solution to penetrate every part of the workpiece and enabling a more thorough cleaning. The vacuum condition also degasses the solution, improving the efficiency of ultrasonic waves. (3) Mechanical swing. The transmission mechanism causes the workpiece to swing up, down, left, and right in the cleaning tank, allowing dirt to detach from the workpiece more quickly. (4) Gas-phase cleaning. In the final step of cleaning, the workpiece is subjected to vapor cleaning using a solution vapor, so that the oils dissolved in the cleaning solution do not remain on the surface of the workpiece. 2. Fast drying speed: High-temperature steam is first used to heat the workpieces inside the drying tank, after which the tank is quickly placed in a vacuum state; the vacuum-induced boiling effect then causes the cleaning solution on the surface of the workpieces to evaporate rapidly. 3. Solvent regeneration and reuse: The vacuum cleaning and drying machine is equipped with a multi-stage vacuum distillation regeneration system. The cleaning solution containing oil contaminants in the cleaning tank is continuously drawn into the distillation unit, where it is heated and evaporated under vacuum; thereafter, it is condensed back into a clean solvent that is then returned to the cleaning tank, thus keeping the cleaning solution in a clean state at all times. The oil residue remains at the bottom of the distillation unit and is removed regularly. 4. Low solvent consumption: Solvent vapor is recovered through a condensation recovery system during vacuuming and drying processes, resulting in a loss of cleaning agent of less than 0.04%. 5. High safety: The vacuum cleaning and drying machine ensures safe operation by using explosion-proof motors, explosion-proof switches, indirect heating with heat transfer oil, combustible gas concentration alarms, automatic door closure, automatic power shutdown, and automatic fire suppression systems. IV. Promotion directions for HY series cleaning agents and vacuum cleaning dryers Hydrocarbon cleaning agents and vacuum cleaning dryers are widely used in Japan, and more than 30 vacuum cleaning dryers introduced to China by Japanese-owned companies have been installed there; however, the cleaning agents used are mostly imported from Japan. On August 14 this year, at the International Symposium on the Cleaning Industry and Training Session for Domestic Experts held by the **Environmental Protection Administration, our company introduced its HY series of cleaning solvents and vacuum cleaning dryers to the attendees. These products received widespread recognition, and for the first time, hydrocarbon-based cleaning agents were acknowledged at a **-level meeting as an important alternative to F-113. Our company has also become a member of the ATSS for the alternative technology support in China’s ODS phase-out program in the cleaning industry, thanks to its strong technical capabilities and mature products. Drawing on the proven experience of Japanese companies, the HY series of cleaning solvents can be used in manufacturing industries such as machinery, electronics, automotive, home appliances, instruments, and optical equipment. The main components that can be cleaned include: motor parts, printer components, fiber optic cable components, hard drive components, chip frames, camera components, valve components, optical drive components, VCR components, microwave oven components, light-emitting diodes, ballpoint pen tips, inkjet nozzles, floppy disk heads, engine parts, kerosene stove nozzles, compressor components, LCD fixtures, copier components, air conditioner parts, capacitive piezoceramics, instrument components, microswitches, computer stamping parts, textile machine accessories, filters, ultrasonic components, lenses, button batteries, solar cells, quartz oscillators, watch components, printed circuit boards, mobile phone accessories, automotive parts, pre-painting treatment, battery components, cleaning before and after heat treatment, refrigerator copper tubes, finely processed parts, electronic components, and bearings. It is evident that the HY series of cleaning agents and vacuum cleaning dryers not only hold a leading position in China but also have broad market prospects. We can promote our products in the field of process cleaning using the following methods: 1. Recommend the HY series of cleaning agents to customers who are currently using vacuum cleaning dryers and imported hydrocarbon cleaning agents. 2. Identify enterprises that still use halogenated hydrocarbon cleaning agents, and recommend the use of vacuum cleaning dryers and HY series cleaning agents. If they meet the requirements of China’s ODS phase-out plan for the cleaning industry, our company can recommend them to the State Environmental Protection Administration for funding from the United Nations Montreal Protocol Multilateral Fund. 3. For cleaning equipment using halogenated hydrocarbon cleaners, recommend to customers the installation of vacuum drying and vacuum recovery units. 4. Participate in the bidding for new project construction and equipment renovation. 5. Collect information on newly established enterprises and project approvals, and recommend vacuum cleaning dryers to the design firms so that they are included in the design plans. ( ) This post was last edited by eastchen on 2009-4-13 18:13 ]