русский
Español
FrançaisIndustry News
Foam in waterborne coatings, inks and adhesives appears during production and application, yet treating foam alone can disturb system wetting and film appearance. Starting from surface tension changes makes it possible to reduce foam while keeping substrate wetting, dispersion and later film formation in view.
1Introduction
Waterborne coatings can produce foam to varying degrees during high-speed dispersion, grinding, letdown and application. In high-speed mixing or high-pigment systems, air is easily drawn into the coating.
Foam that stays for a long time affects metering and filling during production, and after application it can lead to surface problems such as craters.
Defoaming in waterborne systems is not simply "the less foam the better". Some additives reduce foam but may change the wetting state of the system. If they are not compatible with components such as the resin and pigment, surface defects can follow. So when choosing a waterborne defoaming additive, look at foam, wetting and system compatibility together.
2Why foam forms
Waterborne formulas use water as the main dispersing medium and usually also contain resin, pigment, wetting agent, dispersant and other components. These ingredients influence the surface tension and flow behaviour of the liquid.
During high-speed dispersion the impeller keeps drawing air into the system; if bubbles in the liquid do not break easily, a lot of foam forms. In waterborne color paste production, adding and grinding pigment further increases the chance of air entering.
Foam problems are often not caused by a single production step but relate to the whole formula and processing.
3Why wetting matters
A defoamer takes part in the interfacial changes of the system. If its match with the system is insufficient, new surface problems may appear after it is added, such as a changed spreading state of the wet film or local appearance differences in the dried film.
Defoaming and wetting are therefore not two completely separate issues for waterborne coatings. In systems that must balance pigment dispersion, substrate wetting and surface appearance, the overall state after the additive goes in needs closer observation.
4DH-2104E
DH-2104E is a nonionic surfactant with wetting, defoaming and dispersing functions. Its structure lowers the surface tension of the system while taking both foam and substrate wetting into account. Three aspects deserve attention:
Foam stateWatch how foam forms and fades during high-speed mixing, grinding and application.
Wetting stateFor pigment concentrates, watch wetting, dispersion and paste condition after the pigment goes in.
Film appearanceKeep checking surface flatness, gloss and the state after storage, not only the defoaming effect right after addition.
5Testing different systems
The reference dosages in the DH-2104E data are:
Waterborne coatings0.1%-3.0%
Fountain solution0.1%-1.0%
Inkjet ink0.1%-1.0%
Waterborne pressure-sensitive adhesive0.1%-1.0%
In a real formula, start with small trials at several dosages. For a waterborne coating, observe foam height after high-speed mixing and how the foam fades at rest, then run an application test. For waterborne color paste, also observe pigment wetting, paste viscosity and the state after storage. For systems needing high surface quality, add a film appearance test so the dosage is not judged by defoaming speed alone.
Frequently Asked Questions
Why is foam so common in waterborne systems?
Water is the main medium, and resin, pigment, wetting agent and dispersant change surface tension and flow. High-speed dispersion draws in air, and pigment addition and grinding add more.
Is less foam always better?
No. Some additives reduce foam but change the wetting state, and poor compatibility with resin or pigment can lead to later surface defects.
What type of additive is DH-2104E?
It is a nonionic surfactant with wetting, defoaming and dispersing functions, and it can be used in waterborne coatings, waterborne pressure-sensitive adhesives, fountain solution, inkjet ink and pigment concentrates.
How should the dosage be decided?
Set several dosage levels for small trials, compare foam, application and film state, and then settle on the amount that suits the specific system.
SummaryFoam in waterborne systems often relates to mixing method, pigment state and the various surface-active components in the formula. When choosing a defoaming additive, evaluate wetting, dispersion, compatibility and film appearance together with foam changes. DH-2104E is a nonionic surfactant with wetting, defoaming and dispersing action. Set dosage levels for the specific formula and compare foam, application and film state before fixing the amount.
