Discussion on Technical Countermeasures for Surface Coating of Metal Packaging Containers
Discussion on Technical Countermeasures for Surface Coating of Metal Packaging Containers
Sinopec sells Baoji Company Wang Chengxian
I. Development status of China's coating industry
In the 1950s and 1960s, there was no systematic coating industry in China. Only a few spraying equipment factories produced spray guns, painting machines, paint mixing drums and drying boxes. The painting equipment of each factory was manufactured by itself. Parts such as degreasing, rust removing kerosene, gasoline, acid, alkali, sandpaper and sand blasting, manual operation, coating is also manual operation, no drying process except for amino coating drying. Labor intensity is high, efficiency is low, pollution is serious, and quality is not high.
From the late 1970s to the end of the 1980s, reform and opening up promoted economic development. At the same time of constructing a large number of various enterprises, the introduction or the coating production line designed by China itself has been put into production, such as: refrigerators, washing machines, air conditioners, automobiles, motorcycles, motor casings, tractors, steel drum painting lines, etc. It reached the level of the early 1980s. After more than ten years of development, it has formed a central location (not yet formed a corporate group).
The first central location is centered on Jinzhou and Chengde. The scale is large, the development is earlier, the technology is more mature, and it is radiated to Beijing, Changchun, Heilongjiang and other places. The backbone enterprises include Jinzhou Quartz Glass Factory, Jilin University, Jinzhou Infrared Technology Research Institute, 53rd Research Institute of Electromechanical Department, Chengde North Suspension Conveyor Factory, Changchun Far Infrared Equipment Factory, Beijing Coating Equipment Factory, Tianjin University, and Aerospace Department 603 Research It is mainly engaged in the design and manufacture of quartz glass tube type far-infrared components and coating equipment, with an annual output of dozens of coating lines. They designed and manufactured nearly ten painting lines for the barrel factory.
The second central location is centered on Shanghai and Sunan. Mainly based on township enterprises, the party is in the ascendant, but lacks the mechanisms and means to further deepen. The backbone factories include Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai Infrared Technology Company, Shanghai Electrostatic Spraying Equipment Factory, Changsha Far Infrared Component Factory, Jixian Arts and Crafts Factory, Wuxi South Conveyor Factory, Wujin Coating Equipment Factory, etc. Production of far-infrared resistance bands, metal tubes, black magnetic tubes, semiconductor ceramic-type radiating elements and coating equipment, manufacturing capacity of dozens per year.
In addition, ultrasonic cleaning equipment and ultrasonic testing equipment from Shanghai, Shenzhen, Guilin, Jining and other ultrasonic instrument factories can be extended to packaging containers.
The southwest and northwest regions are almost blank areas of the coating industry.
Second, the development and countermeasures of painting technology
1. Set up a coating technology team and group
The packaging industry itself has a poor research on painting, and the professional and technical personnel are scarce, and the equipment is mostly provided externally. Because the off-line enterprises do not know much about the manufacturing process of packaging containers, the equipment has such defects or defects, such as the annual base calculation; production program design; pre-treatment and painting relationship; coating temperature and viscosity; drying equipment thermal power and Current density; energy saving and exhaust gas treatment; safety and operating procedures are indistinguishable from the container industry. Therefore, it is necessary to attach one or two typical enterprises, gather a group of high-level professional and technical personnel to engage in the research and development of packaging container coating technology, and broadly, it can be applied to automobiles, tractors, home appliances and other enterprises.
2. Due to the development of computer technology, petrochemical technology, surface treatment technology, ultrasonic technology, far infrared heating and ultraviolet drying technology and information technology, it provides a solid material foundation and design basis for the development of coating technology. The optimized design, combined design, and CAD of the coating design can make the coating equipment reach the perfect level.
Optimization design and optimization control have the following aspects:
1 Pre-coating treatment type, principle, structure, treatment liquid formulation, temperature, optimum value, economic value, serialization, standardization and economic design research, highlighting the research on ultrasonic cleaning technology.
2 coating formulation, thinner toxicity and effect, viscosity, particle size, characteristics, heating curing process and time, curing type, coating method and real-time control design research. Focus on the study of water-based coatings and non-drying coatings.
8 drying mechanism, drying method, drying calculation formula, matching wavelength, radiation and absorption, optimal temperature field in the drying tunnel, structure, current density, energy conversion mode, convection mode, thermal insulation, thermal bridge, hot air curtain , radiator surface temperature, total radiance, heating time, drying speed, temperature control mode and corresponding research and design of transport methods. Focus on far infrared drying and solar composite drying technology. Printing iron UV drying technology.
4 Research on semiconductor electrothermal coatings and CAD of coating control line PC control and painting design.
5 Wastewater, waste slag, waste gas treatment and design of green technology and green products, focusing on research and development of ultrasonic treatment technology, water-based coating, solvent-free cleaning, cyanide-free plating, and waste gas treatment technology. My country is a signatory to the Brazilian Conference on Peace and Development and must meet environmental pollution control goals by the year 2000. In particular, it is necessary to eliminate environmental pollution caused by acids, alkalis, benzene, and phenols. Adhere to energy conservation, pollution control and equipment, synchronous design, simultaneous construction, simultaneous production, and finally research and design coating equipment without three wastes. This can be done from the current technical results.
3. Innovative discussion of several key technologies
The key technologies in coating technology are high quality degreasing, descaling, cleaning and phosphating technologies, energy saving technologies, low toxicity or non-toxic coating technology, automation technology, combined design techniques and CAD.
Although China can produce more than one billion tons of coal in the world, the effective utilization rate is very low, only 30%, and developed countries reach 50%. The waste of one-time energy is quite large, reaching 20-30%. The gross national product per ton of standard coal output is only one-third to one-half of the developed country, and the product consumption is 40% higher than that of advanced countries. The energy is very tight and the energy-saving task is very urgent. Painting is a major energy consumer, and the development of energy-saving drying equipment is an inevitable condition for the survival of the coating industry.
Composite solar drying technology (solar energy when solar radiation is strong, other energy when not strong, automatic switching), far infrared drying technology, ultraviolet drying technology are modern advanced drying technology, and strive for technology in 2000 years ago A breakthrough has been made.
Since the country listed infrared heating technology as a key promotion project in 1978, it has experienced several ups and downs. In the second promotion of infrared technology in the 1980s, the white quartz far-infrared radiator, the direct-heating resistance band radiator, the black magnetic tube, the metal heating tube, and the semiconductor ceramic heater were developed. The heating temperature is gradually developed from low temperature (below 60 ° C) to medium and high temperature. The total radiance is 0.88, the thermal efficiency is over 57%, and the energy saving effect is very significant. In this climax, the foundation of far-infrared heating materials was basically laid, and theoretical research has also achieved remarkable results.
Solar drying technology has a bright future. There are also solar ovens in operation in Beijing, but the cost is higher. Silicon solar cells with a solar conversion rate of 40% and a cost per watt of less than one dollar have been developed. The amount of solar radiation reaches 1kw/m2. China's total radiation amount is trillions of kilowatts, which is a huge natural energy source. The application of solar energy in the coating industry is one of the development trends.
Ultrasonic degreasing, descaling and phosphating technologies are energy-saving, fast, useless or less solvent, no pollution, and clean. The author has a special article (see "Steel Barrel" No. 2, 3, 1995) is a technology worthy of development.
Water-based (water-soluble) coatings have been developed in a variety of ways. At present, ambient temperature curing coatings are produced at home and abroad. It has many advantages over thermosetting coatings, energy saving (without drying), and low pollution (less solvent or no solvent, only water is used as a diluent), such as Nanjing Yuchen Machinery Factory Co., Ltd. The self-produced steel drum inner wall anti-corrosion coating epoxy series does not need to be dried, Lumiflon (remaining US Fulun) developed by Asahi Glass Co., Ltd., fluororesin coating, water-based coating of Beijing Red Lion Coatings Co., Ltd. At present, there is a rust coating. If it can be further modified as a topcoat, the pre-coating treatment will be eliminated, which is of great significance for energy saving and pollution elimination. It is worth mentioning that if the powder coating can be used to reduce the cost and use it on the steel drum of the packaging container, it is the future development direction.
A variety of low-toxic, non-alcoholic thinners have been successfully developed in the 1980s. For example, Shenyang Dongling Energy Conservation Research Institute has successfully developed phenolic, alkyd, amino, nitro and electrostatic spray thinners, using naphtha and pumping. The oil has been added to the chemical raw materials, and the National Environmental Protection Agency has promoted the application. Guilin and Guangdong also have similar products. The most characteristic of such diluents is alcohol-containing, low cost and basically non-toxic.
Automation and combined design will be described later.
The author believes that the following painting modes are worthy of research and development:
Ultrasonic degreasing phosphating + water soluble coating coating + far infrared radiation convection drying (or composite solar drying) + PC control + exhaust gas treatment.
Ultrasonic degreasing, descaling, phosphating + drying-free room temperature curing coating coating + PC control + exhaust gas treatment.
With rust disposable coating + far infrared radiation convection drying (or composite solar drying) + PC control + exhaust gas treatment.
Third, coating technology research and development topics
1, pre-treatment (green processing technology)
Ultrasonic degreasing, ultrasonic phosphating, ultrasonic finishing (polishing, deburring), ultrasonic passivation, hydrocyclone cleaning and degreasing, electrochemical cleaning, descaling, non-polluting neutralization, shot peening, rust removal, etc. . Wash the phosphating temperature and solution.
2, paint and thinner (energy-saving or green)
Water-soluble paint, free-drying coating (normal temperature curing), rust topcoat, low-grade (low-priced) powder coating, semiconductor electrothermal coating (for far-infrared radiation components), room temperature curing inner coating, room temperature curing high-fidelity printing iron ink coating Wait.
Alcohol-free low-toxic diluent, water-based non-toxic diluent, etc.
Coating and solvent recovery, regeneration, exhaust gas adsorption mechanism and chemical neutralization reaction non-toxic emissions, wastewater treatment technology.
3. Coating and exhaust gas treatment
Constant temperature coating, high pressure airless spraying, printing iron, coating and ink filtration blending, multi-channel multi-color coating, color coating, internal and external joint coating, electrostatic coating.
Water curtain air supply type exhaust gas treatment, hydraulic spinning type exhaust gas treatment, liquid adsorption type exhaust gas treatment, chemical reaction type exhaust gas treatment.
4, drying and cooling coating curing
Through-type double-bridge full purification far-infrared convection dryer, far-infrared solar convection composite dryer, ultraviolet oil, ink coating dryer, microwave dryer, different paint drying mechanism, drying theory basis, drying structure Optimization, energy saving research, drying energy conversion and efficiency, drying component research and development.
5, the conveyor
Roller chain flat conveyor, plate chain flat or hook type, conveyor, hanging conveyor, manipulator, magnetic conveyor, pneumatic conveyor, turntable conveyor, belt conveyor, vibration transmission machine and conveying speed Device (grade and stepless).
6, automatic control system
Degreasing and descaling automatic control system (temperature, pressure, flow, solvent concentration and replacement, degreasing, descaling (oxidation wave) determination. Phosphating automatic control (solution formulation, concentration, temperature, ultrasonic intensity, rehydration addition).
Infrared automatic control system (surface temperature, temperature gradient upper and lower limits, voltage, current, electric power, thermal power, convection and fan control system (flow rate, wind pressure, air volume, intake and exhaust, fan shift)
Coating automatic control system (flow, temperature, pressure, adjustment, color matching, adhesion, viscosity, real-time control).
Exhaust gas control system (exhaust gas concentration, upper and lower limit setting, patrol and alarm, automatic stop heating and rapid exhaust).
?, full line control system
Coating production line real-time control system (PC or CAM). Production line safety control system, self-locking device.
8. Basic research
Serialization standardization research; reliability design; computer optimization design and software development (CAD), module design, combined design, coating technology external environment.
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