Coating technology: Application of special effect pigments in powder coatings

powder coatings are increasingly used in Europe, the United States and Asia-Pacific markets due to their non-volatile organic compound (VOC) emissions and their high efficiency and durability propertiesThe innovation of coating technology has opened up a new market for powder coatings and has been used in more applicationsPowder coatings can be used in high-gloss, low-light, flat-light and metallic coatings with out-of-limits colorTHE BR-SPECIAL-EFFECT PIGMENT CREATES A UNIQUE, DAZZLING VISUAL EFFECT FOR POWDER COATINGSIn fact, they apply to all resin systemsMany of them can also be used in outdoor durable coatings and industrial coatingsBR powder coatings have advantages of BR-BR-new options: powder coatings do not emit (VOC) during curing, which allows them to replace more traditional niprotosis solvent-based and water-based coatingsBR- Efficiency: Powder coatings are highly efficient because they are 100% solid and produce little or no wasteIt does not require a solvent collection systemIf necessary, the paint booth can be built in a relatively small spaceMoreover, because both the transfer and curing equipment can be switched between them, the liquid coating system can often be easily replaced with a powder coating systemReplacing a liquid transfer system requires a certain cost, but this can quickly recover the investment by increasing efficiencyBR- Durability: Powder coatings are more resistant to acid rain and UV rays in sunlight than liquid coatingsThey are weather-resistant, durable, stone-hit and scratch-resistantThey have been effectively used in products that require durability, such as building panels, office furniture, outdoor equipment, home appliances, children's toys, bicycles, car hoops, motorcyclesBR - For powder coatings , special effect pigments BR , special effect pigments are more and more widely used in powder coatingsBecause it is not only easy to use, safe and reliable, but also good decorative effect, in the powder coating industry gradually occupies a certain metal pigment market shareThe largest market for BR-effect pigments in construction coatings includes aluminum building sheets and curtain wall panelsThe most common lyint hue in this application is gray totheredThis hue can be obtained in combination with a black or grey slug powder coating in combination with a white slug-type pearleid pigmentMica-effect pigments are cheaper and more durable alternatives to aluminum powder pigmentsMetal pigments require an additional coat of varnishes to increase durability and reduce loss of lightMica-effect pigments do not require another coat of varnishBecause it is chemically inertTHE TRADITIONAL PROCESS OF MELTING-MIXING PROCESS WITH POWDER RESIN CANNOT BE MIXED WITH THE TRADITIONAL PROCESS OF EXTRUSION AND CRUSHING GRADING BY THE MIXING OF BR AND RESIN PIGMENTSBecause this process will cause pigments to break down, resulting in the pigment drop or even disappear, but should use dry mixing or bonding processing technologyThe BR-dry blending process is specially developed for the treatment of fragile stoic pigmentsIt uses a P/K tumble mixer and a low shear mixer or a mechanical mixer (a Henshel machine at low speed) to mix powder coatings with effect pigmentsThe homogenous pearlre resin mixture is used to prepare powder coatingsThe bonding process heats the resin to a slightly higher softening point and then mixes it with the effect pigmentThe pigment is glued to the resin to form a wholeIn the BR-dry mixing process, in order to produce a metal effect, the amount of effect pigment stos usually accounts for 3% to 5% of the powder coatingThe concentration of effect pigments in the bonding process can also be increased Some users use very low concentrations of antidote pigments (e.g 0.25% to 1.0%) as a color ant The amount of effect pigment sly needs is determined by the user's requirements THE BR-EFFECT PIGMENT CAN BE MIXED WITH THE TRANSPARENT COLORANT TO GET DIFFERENT COLOR Effect pigments should be avoided with opaque pigments or fillers Because these pigments affect the effect of the pigment with the angle of the color effect Most commercialized powder coatings are not transparent and therefore cannot be mixed with effect pigments In these cases, the larger the particle size of the pigment, the better the effect If possible, the powder coating will get a brighter appearance in two steps: first spray an opaque coating with a pigment, partially cured, and then spread the effect pigment in a transparent powder, completely cured, to get a depth effect coating THE FASTEST GROWING COATING COATING IN THE BR-POWDER COATING INDUSTRY IS APPLIED TO BR-POWDER COATINGS It is important to understand the shortcomings of the current powder coating This section provides an overview of some of the technical challenges in the use of effect pigments in powder coatings for powder coating equipment suppliers to address Researchers are also developing products that can further improve the appearance of the paint film At present, there are two types of powder coating system: corona spray method and friction tape spray method In order to make the effect pigment in the powder coating application effect better, both coating methods require the effect pigment with resin bonded Corona spray methods are more commonly used Friction tape spray method is less applied to coating geometric complex parts During corona spraying, in order for the powder coating to be transferred to the coated object, the coating must first be allowed to pass through an electrostatic field, the coating is negatively charged, and then attached to the coated object with positive charge Although the powder coating dry mixture looks equal, the mica-effect pigment is inert and less chargeable Whether the powder can be charged determines whether the powder coating can be successfully applied to the key Because mica-based co-effect pigments are not easily charged, it is easy to separate them from those charged coatings during spraying onto the coated objects This different ability to charge leads to a decrease in the efficiency of pearlpigment transfer In other words, during the spraying process, a portion of the drop-off of the unelectrophotomes falls into the collection system, which can create many problems The most obvious result is uneven or spot-spotted paint surface Without electro-pearl pigments may also accumulate in the fold-in nozzle, accumulating into a large clump, and then spraying onto the coated object If this happens, the concentration of pearly pigment on the coated object will change constantly, which makes it impossible to obtain a stable paint film during daily production operations Moreover, if the composition of the powder coating is constantly changing when used, the concentration of the paint pigment is different from the initial powder, can not be recycled, the coating manufacturer has to discard a part of the powder, thus affecting the economy of the powder coating However, if the effect pigment is bonded with the resin, you can avoid the above defects, can be recycled or recycled Br is critical to current or voltage control in the corona coating process In most cases, the voltage cannot be greater than 80kV for the ideal spray effect Higher voltages can cause problems with the ionization of the back This occurs during electrostatic spraying, where the amount of powder deposited on the substrate is limited by the accumulation of excess live powder particles The rest of the powder sprayed onto the plate surface is repellent by the previous coated powder coating, forming a shrink hole BR researchers are constantly working to improve the efficiency of existing spraying technologies For example, the technology for automotive varnish powder pulp is very promising In this system, the powder resin is dispersed in the water, which improves the flow and leveling of the powder system, and the coating effect is as smooth as that of a liquid coating THE RELATIONSHIP BETWEEN THE GRANULAR DIAMETER AND PERFORMANCE OF THE BR-POWDER COATING FLUIDIZATION AFFECTS ITS APPLICATION AND COATING EFFECT If pigments are used in compositions, the degree of fluidization changes with the flow characteristics of the pigment Large rhododles effect pigments do not gather together, shake the packaging container, and the fluidity is good This means that the pigment does not affect the overall fluidization, nor does it affect the transfer of powder in the feedhop and transmission system The larger the particle size of the effect pigment, the better the effect is used in the corona coating process Very fine or ultra-fine pigments in the BR powder are easy to clump Looking at it with a microscope, it can be seen that thin-chip pigments are attached together, which reduces the efficiency of the fluidization and transmission system The poor fluidization effect of the powder coating will cause the amount of powder to fluctuate through the spray gun, and the large amount of powder of the authorities will cause the paint film to be uneven when it falls on the coated On the contrary, the fluidization is too good, the ultra-fine material is separated from the powder and removed by the pipe, thus affecting the appearance of the final paint film BR - Conclusion BR - With the increase of the amount of powder coating, the amount of effect pigment sage increases Researchers are constantly working to develop new products to improve the level of powder coatings