Problems encountered in the construction of water-based industrial paint and their solutions

As the saying goes, "three-point paint, seven-point construction", water-based industrial paint in the construction process will encounter a variety of different problems, most of them are similar to the problems encountered in paint construction, but water-based industrial paint and paint belong to a completely different system, has its own characteristics and characteristics, internal factors determine external causes, correspondingly, the problems encountered in the construction will have corresponding solutions, the following is the water-based industrial paint construction process paint film common disease phenomenon and prevention.
(1) Problem phenomenon
blistering occurs between the painted surface and the paint film, or between two layers of lacquer film; Cracking but can not level, on the hole, the appearance of small hole is called pinhole

. A fine hole phenomenon of needle tip that appears on the surface of the lacquer film that is falling back through the bottom. This needle-pointed hole is like a pinhole with a aperture of about 100am.
(2) cause
(1) substrate treatment does not meet the requirements, such as the substrate surface with oil, dust, etc., wood moisture content is high, or not pine resin, wood itself contains aromatic oil Remove, when its natural volatility causes foaming, plate surface treatment is not good, wood hair, wood thorns, filling difficulties, wood moisture content is high, wood joints and holes are not filled, there are gaps in the holes and so on. (2) The construction environment temperature is high, humidity is low, or the temperature of the oven is too high, the table is dry fast. (3) The bottom layer is not sufficiently dry, on the construction of the second time. (4) the paint is too sticky, bubbles are not eliminated; (5) Drag the brush back and forth when brushing, the resulting bubbles are not eliminated. (6) The coat is not set aside for a period of time, high-speed stirring air into the paint. (3) to solve the countermeasure substrate treatment meets the requirements, remove oil, dust, etc. , plate white blank to be polished flat, and then closed with closed primer: before construction wood to dry to a certain moisture content, generally 10% to 12% (2) do not work at high temperature and humidity; adjust the oven temperature to the appropriate range, generally between 35 to 50 degrees C. Lower the oven temperature and let the leveling time be longer. (3) Multiple construction, re-painting time to be fully spaced, until the lower layer is fully dried and then the second construction; Many times spraying, strengthen the drying time of the bottom layer, multiple thin spray, brushing do not drag back and forth, first horizontal, then vertical, and finally straighten the direction of wood grain. (4) with good paint to sit for a period of time, so that the bubble completely eliminated before construction. (5) When there are more bubbles in the paint or lacquer liquid, and the effect is used, there are a variety of desiccants to choose from. Products that already have bubbles, before repair and re-painting must be carefully polished, the bubbles slightly, can be finished after the paint film, sandpaper polished flat, and then finished paint. For serious bubbles, first pick the bubbles, sandpaper carefully polished and cleaned, and then layer by layer according to the coating process repair.
(1) The problem
flash rust (or flash erosion) is caused by the contact of moisture in the coating with the iron surface (e.g. nail heads, steel, etc.). When coatings are constructed in general environments, such as humid climates, the likelihood of such flash erosion is greater, mainly in corroded interfaces or newly rescified steel surfaces.
(2) Causes
The surface of the workbeent is not cleanly treated with floating rust or oxidizing skin, the temperature is low, the humidity is high, the water is volatile slowly, the paint film is thick, the paint film is dry slowly, and the production of flash rust may dissolve with iron compounds. Related to precipitation, the severity of flash rust depends on the coating system, coatings such as polyvinyl acetate latex at low pH, low temperature and high humidity, extended the contact time of water and substrates, prone to flash rust;
(3) Solution
Treat the substrate cleanly, coating surface treatment should not have more serious floating rust, rust spots, oxidizing skin, debris, etc.; The use of flash inhibitors (such as sodium nitrite, sodium benzoate and sodium tetbonate) is used to inhibit the production of flash erosion, and after the appearance of flash rust, the paint film should be dried, after a moderate grinding and then painted a rust-proof paint, otherwise the rust point will continue to migrate to the surface.
(1) Problem phenomenon
The coating film in the use of the process of non-continuous appearance changes, dry coating film produces a visual line, multi-angled, or indeterm cracks or cracks, cracks from small to large, from shallow to deep, and ultimately lead to complete destruction of the coating film. Cracking is a more serious disadvantage, according to the depth of cracks can be divided into: fine cracks (light surface cracks and generally distributed in a pattern of rules on the coating film), small cracks (similar to fine cracks, but its cracks are deeper and wider), deep cracks (cracks wear at least through the cracking form of the coating, which can eventually lead to complete damage to the coating film), cracking (a cracking form that is wide cracked and similar to a turtle shell or crocodile skin), and crow claw cracking (crack patterns are a form of cracking like crow claws).
(2) Causes
Wood has too high water content, cracks in the substrate, or too loose and rough, poor handling; Poor matching, such as hard coating coating on elastic coating, or mixed with a different nature of the coating, coating dilution of excessive coating film is too thin to resist cracking, low temperature coating, or in the face of high winds, or low surface temperature of the work piece, coating dry film bad cracking, paint or powder in the paint excessive, poor film characteristics.
(3) Solutions
(1) Test wood moisture content of more than 14%, strengthen the treatment of substrates, primer not only oil removal, rust removal, de-fouling should also have a certain degree of roughness, if necessary, with fine sand paper slightly polished, wood treatment, the need to remove the pine resin, wipe clean with ethanol, the pine fat part closed and then coated. (2) coating film once coating can not be too thick (thick film coating, can ensure a certain mechanical strength except), according to the process requirements to strictly control the bottom, surface coating thickness, coating should have a certain coating interval, primer to dry through, and then paint. (3) To enhance the matching between the coating, emphasizing that the expansion performance of the base coating and the surface coating should be close, supporting the use of the "bottom hard surface soft" principle, a variety of coatings mixed, should choose a compatible nature of the coating. (4) In accordance with the construction requirements of water dilution, excessive dilution resulting in the formation of a complete coating film. (5) Do not work in harsh climate, control work parts temperature higher than the minimum film temperature. (6) Adjust the formula to control the appropriate Yanjibi. (7) The coating film has been wrinkled skin, can be smoothed with water sandpaper and re-coated. For cracks that are visible to the naked eye, the coating film has lost its protective function, and the failed coating film should be completely eliminated and re-coated.
(1) Problem phenomenon
shrink hole is a partial contraction on the surface of the coating film, the surface of the coating appears a grain bump similar to the fish eye hemp, as if water spilled on wax paper, spots reveal the bottom of the flower face phenomenon, also known as fish eye. A "shrink hole" is a small, round defect on the surface of a coating that looks like a crater, and the shrink hole is different from a burst hole.
(2) Causes
Oily or oily waxes on the surface of the coating, unclean spraying facilities and spraying tools, oily air compressors and pipes, contaminated environment of the coating line, oil or wax in the air, etc., paint mixed with oil or wax, excessive addition of chemicals such as desiccants.
(3) solutions
(1) coating to avoid contamination, clean the substrate and need to be thoroughly polished. (2) Construction equipment to avoid pollution of oil, wax, etc. , air compressors use oil and water separators, and regular drainage, filter air compressed air, reduce the possibility of air pollution. (3) The work site shall be adequately ventilated to inventory and eliminate the sources of pollution at the coating site, such as volatile solvents, butter, wax or contaminated containers, clothing and shredded cloth. (4) Avoid paint contamination, especially oil, wax, etc. mixed. (5) Paint products using better compatible additives, to prevent additives from being separated from the paint. (6) If the brushing found that there is a "shrink hole" phenomenon, should immediately stop brushing, and with the "shrink hole" part of the wash, to the surface dry, re-painting paint;
(1) Problem Phenomenon
Flowering refers to the uneven distribution of a variety of pigments in the newly coated anti-corrosion coating film, usually in the form of stripes or honeycomb spots, which can be understood as the vertical separation of pigments. Floating color refers to the paint in the wet film after the construction of the coating is horizontal direction layer separation, that is, the coating film in a variety of pigments one or several denser on the surface of the coating film is a across distribution, but with the original formula has a clear color difference. Therefore, hair flowers are color paint surface color incottered, the appearance of spots and stripes, such as the appearance of color clutter defects. Paint contains at least two pigment flowering phenomenon will be obvious; floating color refers to the surface color, but not the same as it should be. Make the coating surface inconsistent with the tone of the interior. Floating color is most troubled with the construction conditions vary from degree to degree, the use of the same paint and different colors.
(2) causes
(1) the particle size of pigment filler particles has a certain effect on the paint floating hair flower, the particle size distribution is wide, floating color hair flower is more likely. In the drying process of coating, particles with fine particle size are easy to float, resulting in uneven distribution of pigments and fillers and causing (2) poor solubility between white base paint and purchased color paste, which will lead to the occurrence of paint film floating flowering phenomenon. (3) Mixed pigment moisture dispersion is not good, the production of flocculation, the accumulation of large particles movement slowly, and unflocculation pigment particles form a movement rate difference, uneven color distribution, the formation of hair flowers, floating color; (4) Pigment particles due to inadequate protection, pigment flocculation, or the occurrence of affinity flocculation, or the presence of bridge flocculation between pigment particles, resulting in floating flowering. (5) Wet film thickness, low viscosity of the base material and slow volatility, will make the wet film in the low viscosity to maintain longer, and make the pigment subside more, so that the floating color intensified.
(3) Solution
(1) Avoid flocculation using low-density fine pigments, volatile faster solvents and a more viscous substiter. When the wet coating film is dry, the solvent evaporates unevenly, causing the surface to produce poor surface pressure and causing conflow phenomenon, which is the driving force to produce floating color. (2) Verify the compatibleness of the base paint and slurry, adjust to meet the standard requirements. (3) Select the appropriate wetting dispersant, remove the pigment type with wide particle size distribution, prevent floating color due to particle size difference, add powder with denaturation such as kaolin, silica ash, four convex rod soil, bentonite, etc., weaken the benardo vortex effect, reduce floating color. (4) According to the formula pigment type (color slurry type), emulsion type, thickener type, wetting dispersant, and filler type, add the corresponding wetting dispersant (5) to follow the "thin coating multi-channel" principle, moisture-free film is too thick, avoid coating stick too low, adjust coating dryness.
(1) Problem phenomenon
biting bottom, refers to the solvent in the upper coating to soften the bottom paint film, solubility, resulting in the bottom paint film adhesion is worse, and caused by the skin, the bottoming phenomenon. When this happens, the coating expands, shifts, shrinks, wrinkles, bulgs, and even loses adhesion and falls off.
(2) cause
(1) primer is not completely dry or primer is oxidized crosslink type or double-group curing type, paint film is not highly oxidized and polymerized into the film before coating, the solvent in the paint will soften the primer dissolved and softened, resulting in the primer is bitten, and separated from the original attached base. (2) brush paint when the operation is not rapid, the number of repeated brushing too many times will produce the phenomenon of bottoming. (3) primer, finish paint does not match, paint solvent solubility is too strong. (4) At high temperature, a one-time spray excessive, so that the coating can not be completely dry, when applied and mandatory drying.
(3) Solutions
The underlying coating should be completely dry or after the reaction is complete, and then brush the coating layer paint; Should be used in support of the use, avoid excessive one-time spraying, and the coating should be fully dry, avoid coating at abnormally high temperature, for serious bottoming phenomenon, the coating should be completely eliminated clean, until the grass drying and then choose the same variety of paint for brushing.
(1) problem phenomenon
there are more particles in the coating film, particles are the same as tweezers-like bulges, the feel is rough, not smooth.
(2) causes
(1) grass-roots treatment is not up to the requirements, sanding is not smooth, dust, sand particles have not been removed clean. (2) when the paint material is dissociated, the resulting bubbles in the paint liquid is not scattered that the construction, especially in cold weather prone to the phenomenon of bubbles do not disperse, so that the paint film dry after the surface becomes rough. (3) The construction environment is unclean, there is dust, sand particles fall in the paint, dust, sand particles and other debris mixed into the paint, or brushing tools sticky debris. (4) When overspouting, the paint mist pollutes the paint film. (5) The curing agent is not used properly, the two groups are poorly compatible, or not stirred thoroughly before use or filtered to cause particles.
(3) Solution
Apply putty filling at the grass-roots uneven, then sandpaper smooth, wipe off dust and then paint; Windy weather or dusty places should not be suitable for construction, just brushed paint film to prevent dust pollution, timely correction of spraying techniques, try to avoid the phenomenon of super-spraying, reasonable deployment of the compatible two groups, should be proportionally adjusted, should be stirred evenly before use; For advanced decoration, sandpaper or sand wax can be used to smooth, and finally wax, polish, polish.
(1) problem phenomenon
the surface of the lacquer film has a relatively uniform non-exposed round pit, the surface of the coating film is not smooth, showing a bumpy state, like orange peel.
(2) cause
(1) work site temperature is too high, the operating environment has wind, and wind speed is too large, paint spray, the table dry too fast, too late to level. (2) the surface temperature of the work parts is high, or the oven temperature is too high or too early into the oven, so that the coating into a film quickly can not be leveled in time. (3) The surface of the coating is uneven, or the coating between the poor matching, affecting the smoothness of the coating. (4) when the construction of sticky too large or disposable spray too much, paint stretch flow is slow. (5) Spraying distance is too far, air pressure is insufficient, or compressed air pressure is not enough, paint atomization is not good, spraying distance is too close, air pressure is too large, high pressure particle impact, resulting in uneven paint film, spray gun calibre is small, and the distance from the work parts is not suitable, resulting in large paint fog particles, affecting the paint level. (6) The coating sticks too high, or the paint table drys too fast;<