Water-based coating layering, subsiding how to do? It can be solved like this!

The layering and subsiding of water-based coatings is an important problem often encountered in the process of production, storage and use, which not only affects the effect of opening cans, but also changes the performance of coatings. Severe hard precipitation may cause paint to be scrapped and unavailable.
, what is the cause of this phenomenon? In this case, how to solve it?
First of all, we should understand the normal state of water-based coatings:
First, receive water-based paint first by hand to measure the weight of the paint barrel, shaking the paint barrel, there is no very obvious sound, indicating that the water-based paint consistency and viscosity is sufficient .
can, the barrel has no skin, no bubbles in the paint, the overall presentation of lubrication, delicate look, uniform color, the same density up and down.
the paint with tools, with a very good consistency, no obvious layering, lumps. Paint liquid stirring smoothly, pick up tools to observe, paint has a good flow.
coating layering is divided into three different phenomena: water dissociation (dehydration contraction) during coating storage, emulsion during coating storage, and subsidion during coating storage.
the phenomenon and causes
the coating after a period of storage, in the paint surface to separate a part of the transparent light yellow or colorless transparent mucus.
: Hydrate thickeners and hydration thickeners in the type and dosage of improper matching, resulting in the paint in the storage process of incompatible and repulsive. If the two networks in the system are not compatible, one is too hydrophobic, one is too hydrophobic, the use of such thickeners match, water-splits are difficult to control. Usually only the water thickening of the "concentration network" contraction away from free in the paint surface caused by water separation phenomenon.
the phenomenon and cause of the
coating to separate a certain amount of liquid, sometimes with some blue light, in most cases the separated liquid is milky white.
reason: the bonding thickener and emulsion particles are not in good bonding, so that the combined emulsion particles in the storage process de-absorption out, suspended on the surface of the coating, the phenomenon of coating emulsion. The low shear stick of the coating is too low, which also causes layering.
Seeding phenomenon and cause
finished paint in the storage process, the uniformity of the paint internal changes, heavy and large particle size particles in the paint distribution is uneven, vertical direction of gradient changes, from the upper surface to the bottom, the coating has from release to thick change, the bottom even appeared hard precipitation. This phenomenon of coatings is called coating subsidion. Water-splitted emulsions are usually accompanied by subsidion.
reasons: poor dispersion of pigment fillers, particles attached to large particles, thereby accelerating sedimentation, storage time is too long, beyond the retention period of the coating, especially long-term static placement, storage temperature is too high, paint sticky too low, pigment reaction, causing precipitation.
solution to layered deposition
if the precipitation is loose, it can be mixed and re-used. Use a blender to make the paint sample fully mixed, mixing the technique is to pour out part of the upper solvent, stirring the lower pigment filler and resin liquid, to be initially dispersed evenly, and then the poured solvent back, continue to stir evenly (sometimes filtered). If the precipitation seriously appears in the lump, you can use a scraper from the bottom of the container to shovel the precipitation, shredding, and then pour the flow medium back into the original barrel, fully mixed. If the operation according to this method still can not be mixed, there is still dry precipitation, paint can only be scrapped or demoted for use.
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