Choosing the proper defoamer can eliminate foam from waterborne printing inks without causing detrimental effects to the finished print
Jeanine M. Snyder, C. James Reader, Charles R. Hegedus, Air Products and Chemicals, Inc.09.16.11
Conventional waterborne ink formulations are composed of many ingredients including resins, pigments and additives. These additives include waxes, surfactants and defoamers. Surfactants are critical to lowering the surface tension of the ink and to wetting out low energy substrates like films and foils.
However, these surfactants can cause foam problems in the formulation during manufacture and application. The defoamers used to remove the foam or to prevent the foam from forming can often cause surface defects, such as craters or pinholes, in the final print. This may require the formulator to use additional surfactant to overcome the defects creating a negative feedback loop. Therefore, it is critical to select the best wetting agent and defoamer combination that provides a balance of foam control and wetting. This paper explores fundamental and practical defoamer selection criteria and illustrates how choosing the proper defoamer can eliminate foam from waterborne printing inks wit
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