Analysis of environmental challenges of ink printing and VOCs control technology​​​​

1. Working principle of ink printing
Ink printing is a process of transferring ink to the surface of a substrate (such as paper, plastic, metal, etc.) to form graphic information. Its core steps include:
Ink coating: The ink is evenly applied to a specific area through a printing plate;
Drying and curing: Using heat or ultraviolet light to evaporate the solvent or cure the ink to complete the attachment of the graphic.
However, traditional solvent-based inks contain a large amount of organic solvents (such as benzene, toluene, xylene, ethyl acetate, etc.). During the drying process, these solvents will evaporate into the air, forming volatile organic compounds (VOCs) pollution.
2. Main pollution problems in ink printing
VOCs emissions
About 50%-60% of solvent-based inks are volatile components, and VOCs released during the drying process account for 70%-80% of the total emissions.
VOCs not only cause photochemical smog and ozone layer destruction, but also cause harm to human health, such as respiratory diseases, nervous system damage, and even cancer.
Secondary pollution risk
Traditional treatment technologies (such as activated carbon adsorption) are prone to saturation failure and need to be replaced frequently. Improper treatment of waste activated carbon may cause secondary pollution.
Energy consumption and greenhouse effect
The high temperature requirement of the drying process leads to huge energy consumption, and the greenhouse effect of VOCs is dozens of times that of carbon dioxide.
3. VOCs pollution control technology
(I) Source reduction: replacement of green materials
Water-based ink: uses water as solvent, with extremely low VOCs content, and full-color application has been achieved in Taiwan.
Solvent-free composite technology: Use water-based adhesives to replace benzene-containing solvents to reduce the generation of VOCs in the composite process.
(II) End-of-pipe treatment: High-efficiency purification technology
Adsorption concentration + catalytic combustion
Zeolite wheel concentration: Adsorb large air volume and low-concentration exhaust gas through zeolite molecular sieve, desorb after concentrating 10-30 times, and form small air volume and high-concentration gas.
Catalytic oxidation: The concentrated exhaust gas is oxidized to CO₂ and H₂O at a low temperature of 250-400℃ under the action of catalysts (such as platinum and palladium), and the purification efficiency reaches more than 95%.
Advantages: Low energy consumption, no secondary pollution, suitable for large air volume scenes in the packaging and printing industry.
Photocatalytic oxidation
Use ultraviolet rays to decompose VOCs molecular chains, and cooperate with titanium dioxide photocatalysts to enhance reaction efficiency, suitable for low-concentration exhaust gas.
Biological method
Microorganisms degrade organic matter in waste gas, which is suitable for low-toxic VOCs scenarios such as food and medicine, but the cost of strain cultivation is relatively high.
4. The core role and principle of VOC catalysts
VOC catalysts are the core components of catalytic combustion technology. Their working principles include:
Reducing reaction activation energy: Catalysts (such as precious metals or metal oxides) provide active sites to reduce the ignition temperature of VOCs oxidation reactions from 800°C to 250-400°C, significantly reducing energy consumption.
Improving decomposition efficiency: On the surface of the catalyst, VOCs molecules combine with oxygen to cause flameless combustion, completely converting into harmless substances and avoiding the generation of by-products such as nitrogen oxides.
Anti-poisoning design: For components such as sulfur and chlorine that are easy to poison the catalyst, ceramic carrier pretreatment technology is used to intercept harmful substances and extend the life of the catalyst.
5. Industry trends and policy drivers
Policies force transformation: For example, Shandong Province has introduced a low-volatile raw material exemption policy to encourage enterprises to replace sources, and end-of-pipe treatment facilities can be shut down to reduce costs.
Technology integration and innovation: Zeolite wheel and catalytic oxidation combined process has become the mainstream, taking into account both economy and efficiency.
Green certification requirements: Food and pharmaceutical packaging companies need to meet solvent residue standards (such as ≤5.0mg/m²) to promote the popularization of water-based inks and catalytic technology.
Conclusion
The environmental transformation of the ink printing industry requires a two-pronged approach from source material innovation and terminal efficient management. The breakthrough in VOC catalyst technology provides the industry with a low-energy consumption and high-purification solution. In the future, with the tightening of policies and technological progress, "green printing" will gradually move from concept to practice, helping to achieve a balance between economic development and ecological protection.