One of the easiest or most challenging liquid-particle separations found in the process industries is paint filtration. Paint filtration, or more precisely “coatings” filtration, deals with paints, oils, varnishes, and lacquers of varying viscosities, from very thin and low-viscosity to very heavy, thixotropic liquids.
Why do we need filtration for paints?
The filtration technology is not only used in the final process of the product but also utilized in the whole process to ensure the quality of the product.
It is not a reasonable assumption to assume that the liquids used in coatings are clean and free of impurities. Residues can be found in vegetable oils (such as linseed oil or soy oil).
Even though oils are filtered to remove them, these are tiny fragments of residual grain or hull that are produced during the grinding and oil-extraction process.
These granules can enter a drum or tank car and frequently show up as silt on the bottom of the container or shipping vessel. Residues can affect the quality of paint if they are present.
Additionally, film-formers might be waterborne or solvent-borne. It is fairly uncommon for polymeric material surfaces to form in a drum or a tank during storage or transportation (especially if warehouse conditions or the outside environment encounter large temperature changes).
The only way to get surfaces out of a batch that has been ground, mixed, or thinned down may require expensive filtration. Because the particulates are soft, pliable, and flexible, they can easily clog any type of filter, even if it is back-flushable, making removal challenging.
If pigment particles in a batch of paint flocculate, another filtration requirement related to quality arises. Despite the fact that these issues might be caused by a variety of factors, frequently workers’ improper adherence to batch manufacturing guidelines is to blame.
For instance, the difference between dropping one gallon of addition into a batch of 1000 gallons of paint and putting it in gently can be crucial. If you pour it in all at once, it could turn into a polymeric snot that needs to be filtered out.
In conclusion, filtering is frequently the solution to quality issues that were not addressed during raw material arrival inspection, incorrect raw material/ingredient storage, and temperature exposure, or mistakes in the production process.
The filtration types for paint
One of two types of media—fixed, controlled pore size or non-fixed, random pore size—can be found in the most often used filters for paint filtering. Knowing how these two forms of medium differ from one another will help one estimate how each of these filters will operate during the filtration process.
Filters with non-fixed, random-pore-size media include packed fiberglass, woven yarns, and felts. These materials have pores of varied sizes that can expand in response to variations in flow rate and differential pressure. These filters are vulnerable to media migration, channeling, and particle unloading.
The design of fixed, controlled-pore-size medium filters prevents the pores from growing in response to pressure and flow variations.
The overall pore structure of these filters is controlled during the production process despite the fact that they have pores of various sizes, ensuring the quantitative removal of particles larger than a specific size.
Any particles emitted by this kind of filter under impulse conditions should be less than those specified by its removal grade.
Filtration selection
The filtration system for paint must be chosen while taking into account a variety of distinct elements. These include flow rate, permitted pressure drop, level of filtration, and overall filtration cost.
They also include compatibility with chemicals and temperatures. The paint filter cartridges are almost always pleated in modern filtration systems.
In paint filtration, material choice is crucial. It is challenging to choose a filter media that is appropriate for every application since paints have different chemical compositions.
The glues and seals used in filter manufacturing may cause further issues. Polypropylene is often suitable. However, the choice of filter will be influenced by the system’s hydrocarbon content and operating temperature.
Conclusion
Filtration for the paints industry seems easy, but actually, it faces all kinds of challenges. The viscosity of liquids, the different chemical characteristics and the different temperature requirements and etc. In this application, various factors must be taken into consideration to choose the appropriate filtration solution.
Brother Filtration, the professional filtration expert, designs and manufactures various filter cartridges, bags and housings for all filtration problems. Our depth filter cartridges series and depth pleated filter cartridges are the perfect solutions for the paint industry.
