Prevention and treatment of common defects in water-based anti-rust coatings.

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
:
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 covering force, membrane shrink holes, pinholes, uneven surface, outside paint lack of plumpness and gloss and

. 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
:
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 membrane foam holes are: improper selection and matching of desiccants, failure to break up desiccants during the pulping and painting phases, 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 invaded, corrosion occurred.
3. The main reasons for coating shrink holes are: the paint phase used oily too heavy, water is not easy to disperse de-foaming agent, 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, 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 plasticity and thus residual corrosion effect is obvious.
5. The main reasons for poor water resistance (salt) are: poor quality of the substrate and insufficient addition, anti-rust 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 anti-rust material is poor, the paint pigment is relatively high, there are foaming, shrinking holes, pinholes and other fatal defects. Some coatings cover the above defects, but more water-resistant, salt-resistant water, and even salt-fog-resistant.
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 flatness;
prevention and control of common defects in water-based anti-rust coatings
:(1)
from the source of the formula to prevent and control, that is, first try to reduce the surface pressure of the coating. The most important 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, for 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
coating is reduced by using a substrate moisturizer with a small increase and high performance, and with an efficient dispersant.
2. Add adhesion promoters for water-based coatings. Silane coupled agents are highly fluid and can be freely migrated to an organic/inorganic interface, and acrylic emulsion coatings are ideal for adding silane adherents. 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 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, the surface pressure of the coating will be reduced, adhesion will be increased.
Reasonable to take the above measures, those self-drying primer peeling, foaming, attachment is not secure, the surface of the paint is uneven, not smooth, not full, paint life is not long and other defects can be effectively prevented and resolved.
prevention and control of common defects of water-based anti-rust coatings
:(2)
prevention and control of water-based coatings, but also depends on a reasonable production process.
1. Fineness: the slurry dispersion and grinding is not thorough, the fineness is higher, there will be uneven paint film, loss of light and
; 2.pH: Water-based coatings should be maintained in a partial alkaline state, in order to make the emulsion stable, paint unchanged quality, corrosion suppression;
3. viscosity: whether the viscosity of the coating is appropriate, related to construction and storage stability, viscosity from rheumorants, the amount of rheoid additives given in the formula is only a subjective data, the actual production process, the need for technical personnel flexible grasp, on-site testing.
Water-based anti-rust coating common defects prevention and control
:(3)
for water-based coatings and rust-proof performance, such as coating film adhesion, water resistance, salt water resistance, acid-alkali resistance and other defects, simply put, mainly from 3 raw materials to solve.
1. Choose a resin with good water resistance, a certain hardness and flexibility, self-interlinking, with rust-proof substances, the use of rust-proof silicon sol to change the resin, can improve the density and adhesion of the coating, and coating hardness and water resistance, salt water resistance, but when using it should be careful of its activity, so as to avoid thickening after the coating.
2. Choose high-efficiency and environmentally friendly anti-rust pigments, "zinc phosphate aluminum" (ZAP) composite anti-rust powder anti-corrosion effect is good. The material contains no heavy metals, is not toxic, is compatible with different resins, will not re-thicken, its composition is easy to hydrolyzed to produce phosphate root ions, and iron ions chelate, thereby blunting the steel surface.
3. Supplemental use of some anti-flash rust agents, corrosion inhibitors, play an auxiliary anti-corrosion role. Such as containing metal soap type of organic rust inhibitor, cost-effective is also high.
Surface rough, multi-foam, shrink hole, poor appearance of the solution
:
for the general-purpose water-based paint surface rough, multi-foam, shrink hole, poor appearance, post-thickening or after thinning and other defects, can be used more than 2 kinds of wetting dispersants, in order to grind out enough fine slurry, for the coating film to provide adhesion, fineness, gloss, stain resistance and so on. 2 kinds of defoiling agent, can expand the scope of defobbing, pulping stage can be used mineral oil defoiling agent, painting phase with compatible antifouling agent, such as sioxane, in order to provide paint film surface bubble-free, pinhole-free , non-shrinking performance and flat, smooth, decorative performance, more than 2 kinds of film-forming additives, such as phenylphenyl alcohol or propylene glycol ether, silicone emulsion with TEXTANOL, with a small number of different volatility rate Alcohol ether-assisted solvents, conducive to the formation of a coating at the right time a continuous complete, dense and uniform coating film, so as to provide the coating adhesion, water resistance, aging resistance, soil resistance and other properties; , polyurethane, fluorine-containing leveling agents, hydrophobic modified alkali-soluble thickening agents, are good performance and low-cost fluidization aids, can provide leveling, gloss and fullness for the coating film.
.