When selecting defoamers for inks, it is necessary to consider the characteristics of the ink system, application
scenarios, and the performance of the defoamer. The following are key steps and considerations:
I. Analyzing Ink System Characteristics
Type and Base Material
Solvent-based inks (e.g., petroleum solvents, esters, ketones): Prioritize solvent-based defoamers (e.g., polysiloxanes,
fatty amides), ensuring good compatibility with the solvent to avoid demulsification or cratering.
Water-based inks (water as the medium, containing resins, pigments, and surfactants): Select water-based defoamers
(e.g., polyether-modified siloxanes, mineral oils), paying attention to shear resistance and water resistance to avoid affecting
system stability or causing cratering.
UV-curing inks: Select solvent-free, low-migration, and UV-resistant defoamers (e.g., modified polysiloxanes, fluorosilicones)
to avoid decomposition at high temperatures or residual odors.
Pigments and Additives
High-pigment/high-viscosity inks: Require shear-resistant and high-temperature resistant defoamers (e.g., polysiloxane emulsions,
organosilicones) to prevent pigment aggregation or defoamer deactivation.
Systems containing surfactants (e.g., emulsifiers, dispersants): Choose defoamers with strong antifoaming properties (e.g., polyethers,
organosilicone blends) to prevent foaming and demulsification. II. Clarifying Defoaming Requirements
Defoaming Speed
Fast defoaming: Prioritize polysiloxane-based defoamers (such as RK-3162, RK-8405), but note that their foam inhibition may be
weaker.
Long-lasting foam inhibition: Choose polyether-based defoamers (such as RK-3062E, RK-8409) or silicone-polyether composite types,
suitable for long-term production.
Compatibility and Side Effects
Avoid cratering, fisheyes, and mottling: Choose defoamers with low surface tension and good compatibility with the base material
(such as modified polysiloxanes), or add them after pre-mixing and dilution.
No impact on adhesion, gloss, or water resistance: Test the compatibility of the defoamer with the ink film properties to avoid
migration or chemical interference.
III. Key Performance Indicators
Chemical Stability
Resistance to acids and alkalis, salt spray resistance (e.g., for metal inks), and resistance to baking temperature (e.g.,
for high-temperature curing inks). >150℃ stability).
Dispersibility
Ensure the defoamer is evenly dispersed in the ink to avoid agglomeration and the formation of new defects (emulsion
or masterbatch type defoamers can be selected).
Addition Amount
Usually 0.1% to 0.5% of the total ink weight. Excessive amounts may lead to pinholes or oil spots. It is recommended to
conduct small-scale tests to determine the optimal dosage.
IV. Experimental and Screening Methods
Small-Scale Testing
Static test: Add the defoamer to the ink and stir, observing the rate of bubble generation and the time it takes for
bubbles to break.
Dynamic test: Simulate production conditions (such as stirring, grinding, and coating) to evaluate the defoaming
effect and system stability.
Comparative Verification
Compare different types of defoamers (e.g., silicone vs. polyether vs. mineral oil), recording the defoaming speed,
foam suppression time, and the impact on viscosity/gloss.
Industry Case Reference
Refer to mature formulations of similar inks (such as plastic inks, paper inks). The company can provide mature
formulation experiments to reduce risks.
V. Precautions
Avoid over-reliance: Defoamers cannot solve fundamental problems (such as system pH value, surfactant type).
The ink formulation needs to be optimized first (e.g., adjusting the amount of surfactant).
Storage and Mixing: Defoamers should be stored in sealed containers away from light. Stir thoroughly before
adding to avoid stratification affecting the effect.
Environmental Protection and Regulations: Food packaging inks require the selection of FDA/REACH certified
defoamers to avoid the release of VOCs or harmful substances.
Frequently Asked Questions and Solutions
1. Problem 2. Possible Causes 3. Solutions
1. Pinholes appear after defoaming 2. Poor compatibility between defoamer and base material 3. Use modified polysiloxane
or a blended defoamer
1. Defoamer easily emulsifies or separates 2. Poor dispersion or excessively high temperature 3. Select an emulsion-type or
high-viscosity defoamer, and lower the addition temperature
1. Pinholes appear in water-based ink 2. Defoamer is incompatible with water 3. Select a polyether-based or
polyether-siloxane blended type
Through the above steps, a suitable ink defoamer can be systematically selected, balancing defoaming effect and product
quality. In practical applications, it is recommended to combine with supplier technical support and conduct multiple rounds
of testing to ensure stability.
