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Federated States of Micronesia What are the ink defoamer for paints(1)

2023-05-11

Federated States of Micronesia Selection of antifoaming agents for different applications:

auxiliary

Flat coating

surface

hardening

dispersant

Features: Low viscosity, low defoaming pressure

Recommendation: Mineral oils or mineral oil modified polyethers

Elastic coating

Features: High viscosity, high ink defoamer pressure

Recommendation: Polyether modified silicone

Surface coating and film covering adhesive

dispersant

Attenuation mechanism of foam
Under the condition of gravity and pressure difference, the liquid membrane of foam will flow and discharge liquid unevenly, and the gas in the bubble will continue to diffuse and permeate due to the different pressure difference on both sides of the bubble membrane, so the instability of foam itself is mainly reflected from the dynamics. [4]
The attenuation mechanism mainly includes the diffusion of gas through the liquid film and the discharge of liquid from the liquid film. These two properties are inherent attributes of foam itself, and have nothing to do with the existence of surfactant. However, these two attenuation mechanisms only play an obvious role in the initial stage of foam system formation. With the attenuation of foam system, these two effects gradually weaken, making the foam attenuation rate gradually slow. [

There is no unified understanding of the mechanism of defoaming agents. According to the mechanism of defoaming agents proposed by predecessors, there are generally the following types: [4]
General defoaming mechanism
Typical defoaming mechanisms with a broad overview are the Robinson defoaming mechanism and the Ross hypothesis. Among them, Robinson mechanism is the basis of Ross hypothesis, which mainly emphasizes the liquid drainage of defoamer destroying foam and Marangoni effect to realize defoaming; The Ross hypothesis is based on the fact that the defoamer particles are insoluble droplets, while some defoamers actually produce defoaming effects in a dissolved state, so the defoaming mechanism of the Ross hypothesis is not comprehensive

Recommendation: Polyethers, which can effectively prevent surface defects and have a small impact on gloss

Water in Water Colorful

Features: More surfactants, stable foam

anti-scratch

The larger the molecular weight, the stronger the control ability of its surface state, and the better its skid resistance and adhesion resistance, such as the 1070 and 1071 series products of the friction chemical industry.
There are two methods for bonding modified polyester or polyether to siloxanes: one is a silicon oxygen bond; The other is silicon carbon chains, which generally have less thermal stability and water resistance than the latter.
The compatibility of polyether and polyester modified siloxanes with resins has been greatly improved, reducing surface tension, controlling surface flow, increasing slip resistance, anti shrinkage, and anti adhesion. Some products also have interlayer adhesion issues. In particular, polyether modified polysiloxanes have poor thermal stability and are prone to foam stabilization. It is important to pay attention to the negative effects of these products when applying them.

Federated States of Micronesia Recommendation: Use polyethers or mineral oil to modify polyethers

Precautions for use of paint ink defoamer:

Before use, stir thoroughly and mix evenly; Adding the paint while stirring; Before use, it is generally not diluted with water; The dosage should be appropriate. Excessive dosage can cause shrinkage, edge shrinkage, poor brushing performance, and other problems; Too little dosage leads to poor defoaming effect; Add it in two stages, namely, add it in the grinding stage and the paint mixing stage, generally accounting for half of the total amount each time. Use defoaming agents with good foam suppression effect in the grinding stage, and use defoaming agents with good foam breaking effect in the paint mixing stage