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    FAQ for Powder Coatings

    Release date:2016-01-27 14:02:31  hits:233

    FAQ for Powder Coatings

    FAQ of laser particle size analyzer’s application in powder coating industry.


    1. Know test report
    General test report involves test parameters, characteristics particle size, distribution curve and distribution form, etc. Electrostatic spraying of powder coatings industry more focuses on the characteristics particle size (D50), particles content (below 10μm), particles content (above 70μm) and other data. These data will show definitely in test report will be clearly displayed. For any confusion, you can dial after-sales service to consult. In general you can put forward to customize special attention parameters according to industry characteristics, competitive suppliers should be able to meet some data requirements of users. Image 2 is particle size distribution data tables of certain coating. You can see it clearly shows the particles content of powder below 10μm and above 70μm.

    2. Differential analysis of test results in dry & wet process
    At present, some clients (especially foreign or foreign-funded enterprises) get used to dry laser particle size analyzer, most domestic clients currently use OMEC wet laser particle size analyzer. Due to the different sampling way, dry test result generally greater than wet, which resulting some doubts. The problem of which one will be more accurate between the two results actually does not exist, because there is no absolute truth value of coating’s particle size distribution, nuance of test results is allowed to exist. If there is a strong demand, also you can make two test results closer by correction. Dry and wet test results difference will not become the obstacles in the process of instrument application.

    3. How to objectively evaluate instrument state
    Bad condition of instrument will seriously affect the reliability of test results. State of laser particle size analyzer includes light path calibration, laser light stability, optical element cleanliness, sample injector stability. In general, instrument software will have background light display window, previous three items can show in this window. There are subtle differences of instrument judgment method for different manufacturers. We take general LS - POP series instruments as an example to introduce. Calibration of instrument light path is judged by the high-low of loop "0" and "1" of light signal, general require loop "0" to reach the calibration of 60 (at least more than 40), loop "1 " to 20 below (where the loop represents actually each and every photoelectric detector in sequential order). Light stability is judged by observing the stability of loop "0". Cyclical fluctuation of ring "0" within one minute should not exceed 5%. Optical device cleanliness is judged mainly by observing the height of ring 15 to 25, the height of these rings was required to be lower than 5. To judge whether sample feeder is stable by observing whether the running sounds of pump smooth, whether there is any air bubbles inside the test window lens, the sample feeder will be all right if these two items show normal.

    4. Dispersion methods and detection skills of wet particle size analyzer for testing electrostatic spraying powder coating
    Poor hydrophilicity leads electrostatic spraying powder coating floating in the water. In dispersion process, usually add a small amount of SDBS or aqueous solution of detergent (concentration 1%-2%) as dispersant, to guarantee the coating particles fully infiltrated into the water. To guarantee agglomerated particles dispersed fully, also need to put the coating particles suspension liquid in the ultrasonic waves for shaking 1 to 2 minutes. Pay attention to your skills when adding sample into sample injector, to ensure uniform sampling and don't take bubbles into injector, which will lead to affect the test results. About measuring parameters setting, refractive index chooses 2.6; analysis mode chooses Rosin - Ram (unimodal distribution mode). Additive amount of sample ensures about 10% beam obstructions, too large or too small will affect the authenticity of test result. Powder coating particles are unfavorable to cycle for too long in sample system. Instrument is not everything, just our hand tools. Only pay attention to the above points, the full dispersion of samples, use the correct test methods and test parameters, you can get reliable test results.

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