1.What is the core principle of water-based alkaline degreasing agents?
Oil stains are removed through a dual process of saponification (reaction with animal and vegetable oils) and emulsification (stripping mineral oils with the help of surfactants).
2.What is the dual degreasing mechanism of basic alkaline degreasing agents?
Saponification: For animal and vegetable oils (such as palm oil) that may remain after cold rolling, alkali agents (such as NaOH) react chemically with them to produce water-soluble soap and glycerin, thus completely converting and removing the oil stains.
Emulsification: For mineral oils that do not react with alkalis (such as the base oil of rolling oil), surfactants in degreasers play a role. They reduce the interfacial tension between oil and water, "cutting" large oil films into countless tiny oil droplets and stably dispersing (emulsifying) them in water, preventing them from re-adhering to the steel plate surface.
3.What are the key operating parameters?
Concentration: A concentration of 2% to 5% is generally recommended. Adjustments may be needed based on the actual oil contamination levels.
Temperature: Generally between 50°C and 90°C. Appropriate heating can significantly improve degreasing efficiency and speed. Some studies have specifically developed degreasing agents that can still operate efficiently at low temperatures of 3°C.
Time: Depending on the process, it varies from a short 2-25 seconds (high-speed continuous annealing lines) to 2-15 minutes (immersion type).
Method: Can be spraying, immersion, or a combination of spraying and electrolysis. Electrolytic degreasing utilizes the large number of bubbles generated by water electrolysis to create a strong tearing effect on the oil film, resulting in faster and more thorough degreasing.
4.Can acidic solvents be used?
"Scale removers" containing hydrochloric acid, oxalic acid, and citric acid. It is crucial to note that unless your specific goal is to remove heavy scale (rust), acidic solvents should be avoided in routine degreasing.
5.How should degreasing be handled for cold-rolled coils?
For large-scale industrial processing, choose a water-based alkaline degreaser operating under heating conditions; this is the optimal solution in terms of efficiency, cost, and environmental friendliness.
For small batches, laboratory work, or special repair parts, consider using fast-drying hydrocarbon cleaners or other organic solvents as supplementary options.