Filtration solutions for Digital Ink Manufacturers

The goal is to ensure continuous printer operation, producing high quality images in every format required. Depth, pleated depth, and membrane cartridge filters all play a part in making this happen through the removal of particulates, agglomerates, gels, precipitates, etc potentially contained in the raw materials used or formed during the manufacturing process.

With the wide range of inkjet chemistries available, specific filtration solutions developed use a range of cartridge filters to obtain the optimum result but can be different from manufacturer to manufacturer on similar ink chemistries.

Pigmented

Often multiple stages of filtration are required after initial mixing to form the dispersion and again after additive addition and dilution. It is necessary to ensure removal of particulates, contaminates and oversized or agglomerates pigments from the dispersion. Depth and pleated depth filters are used.

Solvent based

We need to ensure the removal of undissolved and oversized particulate, but we have the added complication of potential chemical compatibility issues caused by MEK. Pleated depth

Dye based

Key here is the dyes are free of particulate and all organic contaminants otherwise undissolved dye components, gels or bacteria may cause issue at the printer. Typically, pleated depth filters for particulate, gels, etc and membranes used to remove bacteria, although there is discussion currently that all applications could use pleated depth filters if careful selection is made. This is a more economical solution for end users if appropriate due to initial filter and life span.

UV curable

The challenges are far different because additionally to the normal range of contaminates UV curable inks see gel formation during the production process and gels are variable in size and deformable making them difficult to remove. For this reason, depth filters are used because of their depth of filtration media.

The process of manufacturing digital inks consists of three stages (Resin process, manufacturing process and packaging). Each benefit from using cartridge filtration to prevent introduction into the process via raw materials (particulate, bacteria) and removal of potential contaminants created within the process (haze, gels). Similarly deionised water and additives used during the process need treating with similar care.

Although the continuing development of more complex ink chemistries and the improving quality of images continues a pace, filtration solutions are available and in development to meet the future challenges.