русский
Español
Français
Home / News / Industry News / Waterborne Ink Foam Keeps Coming Back — How to Choose and Use a Defoamer That Actually Works
Industry News
Waterborne Coatings & Inks · Defoaming · DH-2271S
In waterborne coating and waterborne ink production, dispersion, grinding, stirring, and application all introduce air to varying degrees. If these air bubbles cannot be released in time, they can enter the film and cause craters, uneven surface, and other film defects. In high-speed dispersion and continuous production, the rate at which the system generates foam is often quite fast — relying on standing alone is difficult to resolve. Therefore, a defoamer in a waterborne system needs not only to deal with foam that has already formed, but also to have a certain sustained foam suppression capability.
Common Problems
1
Large Amount of Foam Generated During Production
High-speed dispersion, grinding, and circulation continuously introduce air into the system, causing foam to continuously form and affecting production efficiency.
2
Re-Foaming Quickly After Defoaming
If the additive primarily acts on instantaneous foam while continuous foam-generating factors still exist in the system, large amounts of foam may reappear after stopping or stirring.
3
Defoamer Insufficient Compatibility with the System
Defoaming capability is not the stronger the better. If the additive is not uniformly dispersed in the coating, it may cause cratering, fish-eye, and other surface problems — affecting film appearance instead.
4
Defoaming Effect Declines After High Shear
Waterborne coating production often requires high-speed dispersion. If the defoamer has insufficient shear resistance, foam suppression performance may show noticeable change after prolonged mechanical action.
Why Waterborne System Defoaming Is More Difficult Than It Seems
Foam is essentially a gas-liquid interface formed when air enters a liquid. In waterborne systems, surface-active substances, resins, pigments, and fillers all influence bubble formation and stability. A defoamer needs to enter the foam interface and then cause bubble rupture by reducing interface stability. But if compatibility between the defoamer and the system is poor, another situation may occur: the foam decreases, but new defects appear on the film surface.
Therefore, waterborne defoamers need to find an appropriate balance between "defoaming capability" and "system compatibility." For waterborne coatings and inks in continuous production, solving foam that has already formed is not enough — it is also necessary to reduce the tendency for continuous foaming during subsequent processing. This is the important significance of sustained foam suppression capability.
DH-2271S: Polyether-Modified Silicone Defoamer for Waterborne Systems
DH-2271S is a polyether-modified silicone defoamer, primarily addressing the defoaming and foam suppression needs of waterborne coating and waterborne ink systems. The product can be relatively easily dispersed into waterborne systems, and while dealing with foam generated during production and application, it also provides a certain level of sustained foam suppression capability. For formulations that require high-speed dispersion, its shear resistance also helps maintain more stable performance.
In terms of system adaptability, DH-2271S has good temperature and acid/alkali resistance, and can be applied across different systems including waterborne inks, clear varnishes, and colour coatings. Before use, it is recommended to stir with relatively low shear force; it can also be added directly according to the formulation process. The product can be used at the grinding or thinning stage. Reference dosage: 0.05%–0.5% of total formulation. The actual amount should be adjusted based on the degree of foaming, the resin system, and the application process.
Summary
Foam problems in waterborne systems often run through the entire production, storage, and application process. Therefore, when selecting a defoamer, it is not enough to look only at instantaneous defoaming speed — sustained foam suppression, shear resistance, and compatibility with the formulation must also be considered. For waterborne coatings and inks, an appropriate defoamer should eliminate foam while minimising impact on film leveling and surface appearance, thereby achieving a balance between defoaming performance and film performance.
Frequently Asked Questions
Why does adding more defoamer sometimes make cratering worse rather than better?
Defoamers work by entering bubble films and destabilising them — but when overdosed, the defoamer itself acts like a localised low-surface-tension contaminant in the film. Areas where excess defoamer concentrates cannot be wetted by the surrounding coating, and craters form in the same way as any other surface tension defect. The effective dosage range exists for this reason: enough to break foam, but not so much that the defoamer disrupts the film surface.
Is the shear resistance of DH-2271S sufficient for all high-speed dispersion processes?
DH-2271S is specifically characterised for shear resistance in waterborne coating production environments. For processes with unusually prolonged high-shear stages or very high rotational speeds, a trial evaluation at production conditions is recommended to confirm that defoaming performance is maintained throughout the specific process. Performance at bench scale may differ from continuous production line conditions.
