Is it often poisonous to smell antifreeze?

From the main components of antifreeze, it can be seen that antifreeze has no obvious toxicity, but it is still harmful to the body after long-term contact or accidental entrance. After all, they are all chemical products. Freezing point inhibitor antifreeze is the main component of antifreeze, accounting for about 92% ~ 98% of the original antifreeze. According to the temperature in different places, the original antifreeze and water can be mixed in a certain proportion to control the freezing point in a suitable range. Effective antifreeze is various organic alcohols. Since 1950s, almost all countries have adopted ethylene glycol as antifreeze. Ethylene glycol is a colorless, transparent, slightly sweet and hygroscopic viscous liquid, which can be dissolved in water in any proportion. The concentration of ethylene glycol is different. The freezing point is also different. The freezing point of ethylene glycol-water antifreeze is not linear with the mass fraction of ethylene glycol. The freezing point of its aqueous solution does not decrease completely with the increase of concentration, but increases when the concentration exceeds 70%. In the process of preparation, reasonable selection should be made from reality to meet the requirements of frost resistance and economy. Generally, antifreeze can be prepared according to the lowest temperature in this area and the data in the reference table 1. In the south of China, the proportion of ethylene glycol is generally 40%, while in the cold north, it is more appropriate to take the proportion of ethylene glycol with a mass fraction of about 50%. The corrosion inhibitor of automobile cooling system is generally composed of copper, aluminum, cast iron, steel and solder. Ethylene glycol antifreeze will cause corrosion of cooling system materials in long-term work, and the corrosion media are water and ethylene glycol. People are familiar with the corrosion of water to metals. Ethylene glycol will not cause obvious corrosion to materials at room temperature, but with the increase of temperature, ethylene glycol will be oxidized, which will increase the acidity and generate a variety of corrosive substances. The precipitation of these corrosive substances will reduce the thermal conductivity of the engine, which will easily block the cooler pipeline and lead to overheating of the engine. Therefore, corrosion inhibitors must be added to antifreeze. Moreover, the corrosion inhibitor to be added has the characteristics of small dosage and good corrosion inhibition effect. Corrosion inhibitors can be divided into two categories: one is inorganic composite corrosion inhibitors, including metasilicate, phosphate, tungstate, borate, nitrite, molybdate and benzoate. As an inorganic composite corrosion inhibitor, it can form a dense passivation film on the surface of metal, blocking or preventing hydrogen and acid penetration of metal. Such as adding 0. 05% ~ 0.03% sodium metasilicate can prevent the corrosion of aluminum parts. The other is an organic composite corrosion inhibitor, which is often used as an antirust additive in antifreeze. Triethanolamine, benzotriazole, mercaptobenzothiazole and organic phosphate are commonly used, which have good corrosion inhibition performance. For example, just add 0. 1% ~ 0.5% benzotriazole can prevent the corrosion of copper parts. Metal parts with different compositions need different corrosion inhibitors. Sodium nitrite has a good corrosion inhibition effect on steel and cast iron, but it causes pitting corrosion on solder. Triethanolamine, phosphate and organophosphate have good corrosion inhibition on ferrous metals, but they are corrosive to brass and copper. Silicate is an excellent corrosion inhibitor for aluminum, but it is easy to hydrolyze and form a large number of flocculent precipitates. Although the cost of these single inhibitors is low, it is difficult to meet the performance requirements of antifreeze in many aspects. At present, the antifreeze on the market adopts a compound formula with synergistic effect of various corrosion inhibitors, and the corrosion inhibition rate is very high. At present, the corrosion inhibitors used in foreign patents are composed of many kinds of corrosion inhibitors, and the corrosion inhibition effect is ideal. It is worth mentioning that benzotriazole and mercaptobenzothiazole are special corrosion inhibitors for copper and brass. Judging from the patents of antifreeze in recent years, at least half of the corrosion inhibitors in the literature contain silicates. Although silicate is unstable and easy to precipitate gel during use, it has a good protective effect on Al, Cu, Fe and other metals, and it is cheap, easy to obtain and completely non-toxic, so it has been used ever since. In order to avoid gel formation, a small amount of silicate stabilizer must be added to antifreeze. There are many reports about stabilizers, mainly siloxane, Si2N and Si2P compounds. Various corrosion inhibitors have different effects on different metals. A corrosion inhibitor has an antiseptic effect on the same metal, but it may have little or no antiseptic effect on another metal. In the presence of a variety of metals, in order to achieve a good overall anti-rust effect, it is necessary to use a variety of corrosion inhibitors to compound. Generally speaking, the total amount of corrosion inhibitor is 0. 5% ~ 5% antifreeze stock solution. Defoamer When a car is driving, air permeates antifreeze to produce foam. The dissolved air in antifreeze oxidizes ethylene glycol, and these foams adhere to the equipment wall, which intensifies the occurrence of pitting corrosion and affects heat conduction. Therefore, an appropriate amount of defoamer must be added to the antifreeze. Defoamer can be silicone, alcohol, dehydrated glycerol ether, etc. The better defoaming agent is alkyl nonionic surfactant. As long as the concentration of defoaming agent is 0. 00 1% ~ 0. 1%, which can achieve ideal defoaming effect. Colorant Adding non-toxic water-soluble colorant to antifreeze is different from ordinary cooling water, which is convenient for observing whether the antifreeze in the cooling system of automobile engine leaks. At the same time, it also has the function of indicator, monitoring the change of pH value of antifreeze, indicating the change of acidity, and reminding users to add stock solution or clean and replace it. The colorant can be bromomethyl blue, phenol red, methyl red, etc. , so that the antifreeze presents a certain indication color. Once it is found that the antifreeze is beyond the indicated range, it means that the antifreeze is acidic and loses its antirust effect. The mass fraction of colorant is generally 0. 0 1% ~ 0.005%. Antibacterial antifreeze is difficult for microorganisms to reproduce because of its high working temperature, but it may cause microorganisms to breed during storage, making antifreeze moldy and deteriorated. Therefore, it is necessary to add a small amount of bactericidal and antibacterial agents to ensure that the antifreeze will not deteriorate during the storage period of 1 ~ 2 years. Commonly used fungicides are zinc chloride, sugar acid and sodium benzoate, among which sodium benzoate is ideal. The corrosion inhibitor added in the buffer antifreeze has a good effect in neutral medium. However, in the working process of antifreeze, the medium will be acidified and the pH value will drop, thus reducing the effect of corrosion inhibitor, or even completely failing. Therefore, it is necessary to add a buffer to the antifreeze, which can stabilize the pH value of the antifreeze in the range of 7. 5 ~ 10 to a certain extent. Both borate and phosphate can be used as buffers.