Prevention and control of common defects in water-based anti-rust coatings (I)

Water-based industrial coatings because of their high surface pressure, easy to produce many defects, it is recommended to take the following methods to prevent and control:
1. from the source of the formula, reduce the surface pressure of the coating, to ensure good adhesion;
2. The production process should be good "fineness, pH, viscosity" three;
3. reasonable coating management and process;
4. Must choose water resistance good anti-rust base, efficient rust-proof pigments and suitable anti-rust additives.
Water-based anti-rust coating common defects
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only to open the can, open the barrel, can see the appearance and stability of the paint, at this time the defects such as floating water, under the lumps, surface bubbly, bad mold and so on. Until the coating construction, can see its effect, at this time defects such as paint flow hanging, poor cover force, membrane shrink holes, pinholes, uneven surface, outside paint lack of plumpness and gloss and so on . After a period of time, if the paint or coating quality is not good, there will be cracking, peeling, foaming, rust and other defects.
The causes of common defects in water-based anti-rust coatings
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1. The main reasons for lacquer film blisters are: the substrate has oil, rust particles, dust, etc. ; With more foaming, the entire coating loses adhesion.
2. The main reasons for the foam holes in the membrane surface are: improper selection and matching of desiccants, failure to break up the desolation agent during the pulping and painting phase, low adhesion of paint when rolling, and failure to adjust the spray gun to the best when spraying. There are bubble holes, holes without paint cover, water and oxygen easily invade, corrosion occurs.
3. The main reasons for coating shrink holes are: the paint phase used oily too heavy, water is not easy to disperse deblisters, emulsion and other surface pressure materials can not be well integrated with other components, etc. , paint spread poor mobility, or the substrate oil, de-foaming agent, film-forming agent, etc. Shrink holes, no paint at the hole, water and oxygen easy to invade, rust out, the protection is empty.
4. The main causes of hardness problems are: related to the watt and addition of the base material, related to the amount and amount of oil absorbed by the powder, and related to the environmental conditions in the film-forming process, i.e. temperature and humidity. The coating film is too hard, flexibility, bending and impact resistance can not pass, the coating film is too soft, water penetration plastic and thus residual corrosion effect is obvious.
5. The main reasons for poor water resistance (salt) are: poor substrate quality and insufficient addition, rust-proof emulsion is not rust-proof, because the surface strength of the coating is greater than the surface strength of the substrate, so the primer and substrate adhesion is poor, the quality of rust-proof material is poor, the paint pigment is relatively high, there are foaming, shrink holes, pinholes and other fatal defects. Some coatings cover the above defects, but more water-resistant, salt-resistant water, and even salt-resistant fog.
6. Paint film appearance (especially paint) defects, paint film uneven, underfleed, gloss is not high, poor visual effect, the reason is due to the paint surface strength, internal non-flowing spread, poor film leveling;
prevention and control of common defects in water-based anti-rust coatings
:
to prevent and control from the source of the formula, that is, first try to reduce the surface pressure of the coating. The main difference between water-based coatings and solvent-based coatings is that the dispersed dilution medium used is different, resulting in different surface pressure of 2 coatings. Therefore, water-based anti-corrosion paint, whether high-grade or low-grade, should reduce the surface pressure of the coating, improve the adhesion of the coating in the first place.
this requires the use of suitable additives:
. 1. The first step to reduce the surface pressure of the coating is to use a substrate wetting agent with a small amount and high performance, and then with an efficient dispersant.
2. Add adhesion promoters for water-based coatings. Silane coupled agents are highly mobile and can be freely migrated to an organic/inorganic interface, and acrylic emulsion coatings are ideal for adding silane adhesives. The most effective adherent on the steel surface is the two-oxygen-based energy silane, but at a higher price. Titanate concedes have the performance of wetting substrates, as well as auxiliary deblistering and leveling. Such as chelated titanium-ester coupling agent, can increase polyester and steel, acrylic and iron adhesion, sexual price is also relatively high. Additives, as long as they are selected, will become another powerful weapon to reduce surface stress.
3. The use of high-efficiency low surface pressure leveling agent can not only expand the primer on the substrate spread surface, increase its attachment point, but also conducive to the flow level of the coating surface, reduce the appearance of filling.
4. Supplementing a certain amount of different volatile rate of alcohol ether combination to help solvents, on the one hand, can better help the substation film, on the other hand, can also reduce the surface pressure of the coating, but to take into account the relationship between addition and drying and construction. Above these additives main positioning, synergy, coating surface pressure will be reduced, adhesion will be increased. Reasonable to take the above measures, those self-drying primer peeling, foaming, attachment is not secure, the outside paint surface is uneven, not smooth, not full, paint life is not long and other defects can be effectively prevented and resolved.
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