Introduction to the performance and application of commonly used additives in ink coatings

As one of the raw materials of coatings, the amount of coating additives is usually small (usually about 1% of the total formula), but the effect is great
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Its addition can not only avoid many coating defects and film defects, but also make the production and construction process of the coating easy to control, and the addition of certain additives can give the coating some special functions
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Therefore, additives are an important part of coatings online coatingol.
com
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Coating aids include conventional organic anti-settling agents, thickeners, leveling agents, foam control agents, wetting and dispersing agents

(1) Organic anti-settling agent

Most of these products are based on polyolefins, using a solvent as a dispersion medium, and sometimes modified with a castor oil derivative

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The main rheological function of organic anti-settling agents is to control the suspension of pigments—that is, to prevent hard precipitation or avoid settling, which is their typical application
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But in practice, it will cause an increase in viscosity and also a certain degree of sag resistance, especially in industrial coatings
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The organic anti-settling agent will dissolve due to temperature rise, thereby losing its effectiveness, but its rheology can be restored as the system cools
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In order for the anti-settling agent to function effectively in the coating, it should be properly dispersed and activated
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Specific steps are as follows:

(1) Wetting (only for dry powder)
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Dry powder organic anti-settling agents are aggregates.
In order to separate the particles from each other, they must be wetted by the solvent and (or) resin
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Usually it is only necessary to add it to the grinding slurry under moderate agitation
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(2) Deaggregation (only for dry powder)
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The aggregation force of the organic anti-settling agent is not very strong, and simple turbulent mixing is sufficient in most cases
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(3) Dispersion, heating, and dispersion duration (all types)
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All organic anti-settling agents have a low activation temperature, and even if the dispersing force is applied, there will be no rheological activity
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The activation temperature depends on the solvent used
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When the low temperature is exceeded, the applied stress will activate the organic anti-settling agent, and can give full play to its performance
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(2) Leveling agent

There are three main types of commonly used leveling agents:

1.
Modified polysiloxane type leveling agent

This type of leveling agent can strongly reduce the surface tension of the coating, improve the wettability of the coating to the substrate, and prevent shrinkage; it can reduce the difference in surface tension caused by the volatilization of the solvent on the wet film surface, improve the surface flow state, and make The coating is leveled quickly; this type of leveling agent can also form a thin and smooth film on the surface of the coating film, thereby improving the smoothness and gloss of the coating film surface
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2.

Such as acrylate homopolymer or copolymer, it can reduce the surface tension of the coating and the substrate to improve the wettability and prevent shrinkage; and can form a monomolecular layer on the surface of the coating film to make the surface tension of the coating film uniform and improve Surface fluidity, inhibit solvent volatilization speed, remove defects such as orange peel and brush marks, and make the coating film smooth and flat
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3.

This type of leveling agent can adjust the volatilization speed of the solvent, so that the coating film has a relatively balanced volatilization speed and dissolving power during the drying process, and prevents the coating film from evaporating too fast and the viscosity is too high to prevent the coating film from flowing and causing poor leveling It can prevent the deterioration of the solubility of the base material and the shrinkage caused by precipitation caused by the solvent volatilization too fast
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(3) Foam control agent

Foam control agents are also called anti-foaming agents or defoaming agents

Generally speaking, anti-foaming agents are composed of three basic ingredients: active compound (ie active agent); diffusing agent (available or not); carrier
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(4) Wetting and dispersing agent

Wetting agents and dispersing agents may have a series of functions, but the main two functions are to reduce the time and/or energy required to complete the dispersion process while stabilizing the pigment dispersion

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Non-ionic wetting agent