Screen printing meshs need to pay attention to the environment when printing, and screen printing meshs will actually have a lot of pollutants during use. Chemical and physical pollutants are the main pollutants. Chemical pollution is mainly inorganic, such as: mercury, chromium, lead, chloride, etc.; organic matter includes organic chlorine, phenol, etc.; physical pollutants mainly include noise, vibration, heat and so on. Due to the different forms of these pollutants, they can be divided into air pollutants, water pollutants and solid pollutants.
1 air pollutants. Including aerosols (smoke, dust, fog), harmful gases (sulfur oxides, hydrocarbons, carbon dioxide, hydrogen chloride, etc.).
2 Screen printing meshs use solid contaminants during the process. Solid contaminants include solid waste such as paper, plastic, glass, metal, ceramics, and wood chips. Noise and vibration are also sources of environmental pollution.
3 water pollutants. Including inorganic suspended solids (slag, iron filings), toxic pollutants (chemical waste such as mercury, lead, chromium, phenol, chlorine), acid-base pollutants (acids and alkalis), oils (oils, lipids, etc.). In addition, heat sources such as hot water and high-temperature exhaust gas may also pollute the water.
Air Pollutants and Treatment Methods in the Use of Screen Printing meshs Air pollutants are substances that enter the atmosphere due to human activities or natural processes and are harmful to humans or the environment. Such as exhaust gas and dust. In screen printing, the volatile harmful gases generated and the harmful dust that can enter the air are mainly sulfuric acid, nitric acid, ammonia, carbon disulfide, formaldehyde, methanol, benzene, phenol, acetone, nitrobenzene, trichloroethylene and chromic acid. Salt dust. Operators who inhale or skin contact with these gases can cause many discomforts, such as respiratory infections, tearing, dermatitis, numbness, etc., and severe cases can be infected with blood diseases and even cancer. Therefore, the exhaust of the screen printing workshop must be processed.
The purification technology of exhaust gas in screen printing mainly includes conversion method and separation method. The conversion method is to purify the pollutants in the exhaust gas through a chemical reaction. The separation method is to purify the exhaust gas by a physical method. The common exhaust gas purification methods are as follows.
1 adsorption method. The adsorption method utilizes the characteristics that the porous solid substance can adsorb the pollutants, so that the pollutants in the exhaust gas are adsorbed on the surface of the porous solid to be separated from the gas, thereby purifying the air. The adsorption method is a common purification method in the screen printing workshop, and is mainly used to purify low-concentration pollutants in the exhaust gas.
2 absorption method. It is the most common method for purifying gaseous pollutants and is suitable for purifying various components such as organic vapors and sulfur dioxide. The commonly used absorbents are water, an acidic solution, an alkaline solution, and an organic solvent. The basic principle of the absorption method is to treat the gas mixture with a liquid absorbent to remove one or more of the components. This absorption method can also be divided into chemical absorption and physical absorption according to chemical reactions.
3 condensation method. The condensation process is generally suitable for the primary treatment of relatively high concentrations of exhaust gases. It can be used to suck back high concentrations of mercury, sulfur, phosphorus, etc. in the exhaust gas. The condensation method uses different saturated vapor pressures of the same substance at different temperatures and different saturated vapor pressures of different substances at the same temperature. Some of the gaseous pollutants are condensed by cooling or pressurizing the mixed gas. It is a liquid or solid, which separates the pollutants from the mixed gas for purification purposes.