Coating knowledge: surface tension problems and solutions in coating construction

Core tip: after coating construction, some of the leveling is very good, and some of them will have various disadvantages, most of which are related to surface tension ① The leveling force comes from the surface tension, which can reduce the surface area of the liquid; at the thin part of the coating, the gas volatilizes relatively quickly, the surface tension rises rapidly, and the coating at the surrounding height tends to spread towards it The paint shall have sufficient flow time before curing to ensure leveling Thick edge phenomenon: the edge surface of the coating is large and volatilized quickly, so the temperature drops and the surface tension increases, and the coating nearby spreads to it automatically, thus forming the phenomenon of edge thickening ② If the coating is wet due to shrinkage Which is the price of Dajin diatom mud Recommended brief introduction: which is the price of Dajin diatom mud? How to buy genuine diatom mud? Guangdong diatom mud agent suggests placing a basin of cold water in the air conditioning room, so that the diatom mud wall can breathe effectively The feature of the breathing wall is obvious When the indoor air is dry, the diatom mud wall will release the absorbed water quickly Put it out to help regulate the indoor dry humidity It is suggested to place a basin of cold water in the air conditioning room, so that the wall of diatom mud can breathe effectively The feature of the wall that can breathe is obvious When the indoor air is relatively dry, the wall of diatom mud will absorb the water Coating home news: after coating construction, some of the leveling is very good, and some will have various disadvantages, most of which are related to surface tension ① The leveling force comes from the surface tension, which can reduce the surface area of the liquid; at the thin part of the coating, the gas volatilizes relatively quickly, the surface tension rises rapidly, and the coating at the surrounding height tends to spread towards it The paint shall have sufficient flow time before curing to ensure leveling Thick edge phenomenon: the edge surface of the coating is large and volatilized quickly, so the temperature drops and the surface tension increases, and the coating nearby spreads to it automatically, thus forming the phenomenon of edge thickening ② Shrinkage phenomenon if a drop of liquid with low surface tension falls on the wet coating, such as solvent or dirt (such as oil) dropped after condensation in the oven, it can reduce the surface tension of the adjacent coating, and spread to a higher surface tension around, thus forming a crater phenomenon, which is called shrinkage ③ Orange peel phenomenon orange peel phenomenon refers to the coating surface slightly undulating, such as the shape of orange peel There are many reasons for the formation of orange peel For example, when spraying, the distance of spray gun is not well controlled, the coating and solvent are not well matched, and the atomization is not good During spraying, the atomized droplets go through a long distance, the solvent volatilizes a lot, and then fall on the wet film Because of the high concentration of the droplets and the high surface tension, the surrounding coating will automatically spread to the droplets, thus forming a protuberance The orange peel phenomenon is also related to the so-called Bernal swirl ④ During the drying process, with the evaporation of solvent, the surface concentration increases, the temperature decreases and the surface tension increases Due to the different surface tension between the surface layer and the bottom layer, a great driving force is generated, which makes the paint move from the bottom layer to the upper layer This movement causes local eddy current and forms the so-called Benard cell The origin of eddy current is like a crater, spraying out the lower layer of coating These coatings with low surface tension spread to the surrounding surface with high surface tension, thus forming a bulge And make the wet film form regular hexagon, its center and edge pigment concentration will be different If the paint leveling is not good, after the film is dry, it will leave the uneven orange peel ⑤ Blooming and floating phenomenon refers to the uneven distribution of pigments in the paint film after construction, which makes the appearance of flower spots (honeycomb stripes) Floating color refers to that the surface color of the paint film is different from that of the bottom layer, and the color of the paint film changes uniformly after construction, which is caused by the uneven distribution of different pigments between the paint film layers The causes of blooming and floating color are very complex, but the causes of uneven distribution (separation) of pigments are all related to the Bernal swirl formed by solvent evaporation: when the paint material moves, it also drives the movement of suspended pigment particles If the size and specific gravity of the pigment are different, it can cause the redistribution of the pigment, and the result is that a kind of pigment has a higher concentration on the surface or some parts of the surface Degree ⑥ Leveling agent in order to overcome the disadvantages of the film in the construction process, leveling agent is often added in the paint to help the film finish leveling process before drying The leveling agent lb-203 of Jinan haozhuijia Chemical Co., Ltd is mainly used to reduce the surface tension of the paint to eliminate various disadvantages; adjust the volatilization speed of the solvent, improve the fluidity, and extend the leveling time; form a single molecular layer on the surface of the paint film to provide a uniform and low surface tension, which can alleviate similar problems of the above latex paint Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,