In the last article we said that silkscreen printing can survive a variety of printing methods, is its irreplaceable characteristics.At the same time, screen printing has its limitations in the current development and research.We need a correct scientific view of the current situation of screen printing, so as to achieve a greater breakthrough.
1. Low screen printing capacity
Screen printing cannot achieve the same production efficiency as the other three printing methods. Firstly, compared with the high degree of automation of offset printing, gravure printing and flexography printing equipment, there are still some differences in the degree of automation of screen printing equipment.
2. Screen printing is seriously polluted
Ink in the printing added a large number of diluent, printing dry, high temperature after the volatilization caused a certain degree of pollution.
3. Complex screen printing process
Screen printing compared with the other three types of printing, the process is more complicated, the use of more consumables, time consumption.
These problems have always constrained the development of screen printing. What are the ways to solve these problems at this stage?
Firstly, aiming at the problem of low production capacity, we can see that the main reason hindering the whole production capacity is the degree of automation of silk screen printing machines.At this stage, we can also see the continuous development of automatic screen printing machines breakthrough.
The working cycle of flat screen printing machine with flat screen plate monochromatic semi-automatic hand screen printing machine as an example, it has a working cycle is: to parts → positioning → plate down → scraping board, ink board up → scraping stroke → scraping board up → scraping board down → plate up → plate up → ink stroke → release positioning → receiving.In the continuous cycle action, as long as the function can be realized, the time occupied by each action should be as short as possible, in order to shorten the same period of each work cycle and improve the work efficiency.
About serious pollution
Common environmental problems and treatment methods in silk-screen workshop
These environmental pollutants can be divided into chemical, physical and biological categories.Chemical and physical pollutants are the main pollutants.Chemical pollution is mainly inorganic substances, such as mercury, chromium, lead, chloride, etc.Organics include organochlorine, phenols, etc.Physical pollutants mainly include noise, vibration and heat source.Because the forms of these pollutants are different, they can be divided into air pollutants, water pollutants and solid pollutants.Contaminants produced by solvents in screen printing inks.Some solvents in screen printing inks.Volatilization or emission into the air will pollute the environment, affect the growth of animals, plants.Especially volatile ink to air pollution is very serious.In addition, some solvents in the ink and auxiliary ignition point is relatively low, in the air and reach a certain concentration, fire will occur.
The exhaust gas can be eliminated by combustion method, or the exhaust gas can be purified by water spray at the outlet.
The pigment waste solution can be treated by purification.The use of slightly toxic pigments must be in strict accordance with national safety standards.Strengthen use management, reduce pollution.
The harmful dust in the air mainly includes sulfuric acid, nitric acid, hydrogen, carbon disulfide, formaldehyde, methanol, benzene, phenol, acetone, nitrobenzene, trichloroethylene and chromate dust.Screen printing in the waste gas purification technology mainly has the conversion method and separation method.The conversion method is to purify the pollutants in the exhaust gas by chemical reaction.Separation is a physical method to purify the exhaust gas.
Condensation method.The condensation method is usually suitable for the primary treatment of gases with higher concentrations.Can be used for back absorption of high concentration of mercury, sulfur, phosphorus, etc.The condensation method is to make use of the same substance has different saturated vapor pressure at different temperature and different substance has different saturated vapor pressure at the same temperature. By cooling or pressurizing the mixed gas, some of the gas pollutants are condensed into liquid.
Absorption method.It is the most commonly used method for the purification of gaseous pollutants, and it is suitable for the purification of a variety of organic compounds, such as sulfur dioxide, etc.Commonly used absorbent are water, acidic solutions, alkaline solutions and organic solvents.The basic principle of the absorption method is to treat a mixture of gases with a liquid absorbent and remove one or more of its components.
We can also see that some new processes are being explored in terms of the complexity of the process.