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Particle Removal & Prefiltration in Ink Jet Ink Formulation

Ink jet printing, regardless of the type of ink, requires the ink to have very low levels of oversize particles or the process will not work efficiently. Continue to read below for more details on removing oversize particles during ink jet ink production, or go to the product selection table at the bottom of this page to explore specific filter options.

Particles can take any number of forms from solids to agglomerated particles to gels and even microorganisms. The particle sizes can range from visible (usually larger than 20 microns) to sub-micron sized. All of them have the potential to clog printheads and cause printing defects. Removing large, solid particles is usually done early in the process, though additional particle removal may be required if a processing step creates particles. Prefiltration is usually defined as the removal of particles only slightly larger than those targeted by the final filtration step. Prefiltration can happen anywhere in the process, but is usually performed after intermediate processing steps and just before final filtration and packaging.

The housings marked “1” and “2” in the schematic show the possible locations of particle removal and prefilters. Assuring that ink components do not contribute particles to the process is a common step, as is particle filtration and prefiltration and after the mixing step. Though only one filter housing (2) is shown for prefiltration in the schematic, multiple filters may be needed based on the quantity of particles in the stream at that point, and the size distribution of those particles.

Common Filtration Steps in Ink Jet Ink Formulation
Particle Filtration in Reprocessing

Custom systems are designed for new applications and to solve challenges in existing processes. Critical Process Filtration will work with you to design, build and install a cost-effective system that delivers the results you need. Contact us or visit our custom filtration systems page for more information.

Application Summary

For more information on this specific application, click on the link below to download an Application Summary.

Choosing the Right Filters

Larger particles or crystals (larger than 1 micron) are most often removed using depth filter media. Smaller particles (smaller than 1 micron) or bacteria (as small as 0.2 microns) will often require more complex membrane filters.

Standard depth filters made using polypropylene or nylon material will capture a range of particle sizes through the thickness of the media. Pleated depth media filters, made using polypropylene or fiberglass, have the advantage of a large surface area that can hold a higher quantity of particles on that surface than the standard depth filters. The material chosen will be based on compatibility with the ink chemistry.

In pleated membrane filters, multiple hydrophobic and hydrophilic materials are available. Hydrophilic materials are most often used for water based inks and include nylon, polyethersulfone (PES), and hydrophilic polyvinylidene fluoride (PVDF). Hydrophobic media for non-aqueous solutions include polypropylene, hydrophobic polyvinylidene fluoride (PVDF) and polytetrafluoroethylene (PTFE).

Our filter media are available in multiple filter formats for all flow ranges. Disc filters support small scale flows in test and research laboratories. Small capsule filters are available for low flow applications such as bench scale systems or small product development systems. Our large disposable capsule filters and cartridge filters are used for larger flow applications ranging from pilot production to full scale operations.

The table below shows the filter media in cartridge, capsule and disc filter configurations. We also have housings for filter cartridges. Click on the PDF Files in the appropriate location to download a data sheet for the filter media and configuration that fits your needs. Critical Process Filtration also has specialty filter devices that may fit your application.

Media Code
Filter Media
Filter Grade
Cartridge Data Sheet
Capsule Data Sheet
Disc Filter Data Sheet
Pore Sizes Avail. (µm)
Melt-Blown Polypropylene Media
1, 3, 5, 10, 20, 30, 50, 75, 100
Continuously spun bonded polypropylene media for consistent 85% nominal performance
Nano-spun Polypropylene Media
1, 3, 5, 7, 10, 20, 30, 40, 50
Very high retention efficiency (99%) and high load capacity to protect downstream processes
Pleated Polypropylene Depth Media
0.1, 0.22, 0.45, 0.65, 1.0, 3.0, 5.0, 10, 20, 30, 40, 60, 100
100% polypropylene construction for high purity
Melt-Blown Nylon Media
1, 3, 5, 10, 20, 30, 50, 75, 100
Spun bonded for consistency with broad chemical compatibility
Pleated Fiberglass Depth Media
0.22, 0.30, 0.45, 0.65, 1.0, 2.0, 3.0, 5.0, 10, 20, 30
High capacity filters for clarification and prefiltration applications
Asymmetric Polyethersulfone (PES) Membrane
0.03. 0.1, 0.22, 0.45, 0.65, 1.8, 1.0, 1.2
Highly asymmetric, hydrophilic PES membrane in single-layer configurations for high efficiency, high flow rates
Symmetric Polyethersulfone (PES) Membrane
0.03. 0.1, 0.22, 0.45, 0.65, 1.8, 1.0, 1.2
Symmetric, hydrophilic PES membrane for high efficiency filtration of water.
Nylon 6,6 Membrane
0.1, 0.22, 0.45, 0.65
For removal of small particles and microorganisms in a wide range of chemicals.
High Capacity Polyethersulfone (PES) Membrane
0.2, 0.5 and 1.0 single layer; 0.5/0.2 and 1.0/0.5 dual layer
High void volume membrane for small particle or bacteria reduction.
High Capacity, Hydrophilic Polyvinylidene fluoride (PVDF) Membrane
0.22, 0.45, 0.65, 1.2
High void volume membrane with high holding capacity for systems that may have high particulate loads.
Polypropylene General Service Grade
0.1, 0.22
Hydrophobic membrane for non-aqueous liquids and gases with excellent material compatibility and low extractables
Polyvinylidene fluoride
(Hydrophobic PVDF)
0.22, 0.45, 0.65, 0.85, 1.0
High capacity, hydrophobic membrane for long life in air and process gas filtration.
PTFE General Service Grade
0.1, 0.22, 0.45, 1.0, 3.0
Highly hydrophobic. Superior air filtration flow rates for tank vent applications

To estimate the number of filters you will need for your application, use our unique sizing tools.

Contact Critical Process Filtration if you have any questions, wish to discuss a specific application or want to learn more about any of our Products and Services. We look forward to hearing from you!