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    Home > Coatings News > Paints and Coatings Market > Functional analysis and solution in powder coating formulation

    Functional analysis and solution in powder coating formulation

    • Last Update: 2020-11-26
    • Source: Internet
    • Author: User
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    1. Regarding the powder to improve the hardness of the coating film
    (1), in the powder coating formulation design, when selecting resin and curing agent, try to choose the glass temperature of the resin and curing agent is high, high official energy film system, so that the cross-link density of the film after the solidification of the powder coating is large, the glassing temperature is high, and the corresponding coating hardness is also high. For example, when choosing pyride polyester, choose a resin with high acid value, choose a resin with high hydroxyl value when choosing hydroxyl polyester, choose a curing agent with high NCO content when choosing a closed polycyanate curing agent, etc.
    (2), in the powder coating formulation design, the choice of high hardness pigments and filler varieties, in this way easy to adjust the hardness of the coating film
    the
    . In addition, in the formulation to improve the pigment and filler quality percentage content (or volume percentage concentration), can also improve the hardness of the coating film, especially to improve the filling method is easy to do. In the filler varieties there is a good material - porous powder quartz, is conducive to the increase of film hardness (principle: porous powder quartz contains Zro2, zirconium dioxide stability, high hardness, coupled with porous powder quartz porous structure makes the coating, that is, has good hardness characteristics, and impact-resistant performance.
    2. About powder boiling foaming
    to a large extent is not enough film cross-link density, reaction is not thorough enough, electrolyte more, coating film Tg is not high enough, hydro-hydropouric group and more substances, coating film temperature resistance is not high enough, coating waterproofing is not good enough and so on. Water vapor enters the material and paint film through the coating film, resulting in bubbles, loss of light, color change, poor adhesion, coating film shedding and other undesirable phenomena. Usually improving the denseness and hydrophobicity of the paint film will improve the ability to cook water. Water-resistant cooking aid group through the reaction and resin and substrate to form a solid chemical bond, improve the density of the coating and water-resistant boiling, coating hydrophobicity is good. Add 0.3-1.5%.
    3. Regarding the powder 90 degree groove corner does not powder problem
    electrostitive spray gun, Faraday cage shielding basically all the additives can not solve the problem, change friction gun, do friction powder is the best way.
    Frictional electricity method - This method, unlike the corona method, it is the use of another principle of action to charge the powder coating, powder through the injection device because of friction electricity, this frictional electricity method is usually applied to complex shapes of components thermal injection situation will be better, static electricity before spraying at a dead end can be improved.
    4. Why is it easy to spit powder
    Because the pearlesco pigment is inherently non-conductive, not easy to carry charge, so in the spray process can easily separate from the charged main powder, this difference in charged properties led to the pearlesco pigment transfer efficiency is reduced, in other words, in the spray process, some non-charged pearlescodesic pigment in thecoating with powder separation.
    5. About wax powder
    powder with wax powder cheap will smoke, require high point recommended with pure point of wax, used to resist scratching recommended with high molecular weight wax, can recommend the molecular weight of more than 6000, used in sand powder and ordinary powder anti-scratch is very good, cost-effective.
    polyamide wax large molecules winding
    a. denaturation is strong, the balance control of the flow and level of thick film coating is excellent.
    b. Not easily soluble in solvents, therefore, there is no risk of granulation;
    c. relatively organic benthic soil easy to disperse; high prices, some products have a shadow of inter-layer adhesion
    polyethylene wax polymer winding
    a. Mainly for anti-sinking agents, no temperature restrictions, there will be no granulation risk;
    b. Good suspension for large particle pigments; widely used;
    c. Plus, providing excellent anti-sinking at the same time, not obvious for coating thickening
    From the application point of view, PA and PE can be used as a slider, used in the coating hardening, because the molecular weight of PA used in the coating will not be very large, 400 or less, PE will be 500-5000, wear resistance is much better than PA. At the same time through the modified, choose different structures, and modified methods, they can also be used as anti-sinking and tactisor use, polyamide in the powder role is not the same, he mainly in the powder for aluminum profiles and cast iron work pieces to help the substrate to provide degassing function, not helpful to scratch resistance, mainly the use of low molecular weight and low viscosity of acetate wax, and epoxy polyester incompatible to help air bubble escape.
    6. Wrinkle floating and dewy bottom problems
    When producing wrinkles, we often encounter floating color, mainly dark powder, mainly due to the separation and migration of hydrophobic pigments and surface stress imbalance caused by dew bottom problems mainly due to viscosity and long coking time caused.
    a. Production is to try to use hydrophosphatate pigment
    b. do wrinkle powder selection particle size is finer>1200 purpose filler, mixture is the pigment and filler premixed evenly before pouring polyester, color phase Recently added wrinkle agent
    c. pigment dispersant and wetting agent
    7. about transfer powder
    anti-lighting agent on the wood texture has a certain effect, the larger the addition of the wood texture is less clear; catalyst varieties and additions It has a great influence on the clarity of wood grain, the clarity of wood grain formed by polyester provided by different manufacturers is different, the amount of filler does not have an effect on the clarity of wood grain, which is not very beneficial, and the clarity of wood grain produced by different amounts of HAA curing agent varies, but different wax powder varieties have a certain difference in wood. The texture clarity of the grain has little effect, the texture clarity of the wood grain formed by the selection of different varieties of nicosium sulfate or calcium carbonate is also different, the variety and dosage of the change leveling agent and degassing agent have little effect on the texture clarity of the grain, but the amount of titanium dioxide powder has a great effect on the clarity of the wood grain. Dosing should not be excessive.
    (1), hot transfer after not good paper or film
    ? a. The surface of the transferred substrate has quality problems, such as high temperature resistance, there is a sticky paper or mucous membrane phenomenon
    b. Powder coating on the surface of the transferred substrate after powder spraying is not fully cured, hot transfer when curing again and sticking back.
    c. thermal transfer glue quality is poor, matching concentration and improper brushing directly affect the effect of paper-stripping.
    d. It is recommended to add a suitable amount of deformant (silicon oil) in the hot transfer glue water, which can solve the problem of paper undressing.
    (2), after thermal transfer of the product speckled or foggy block phenomenon
    a. the surface of the transferred substrate originally has spots or foggy block.
    b. The surface of the transferred substrate is not resistant to high temperature, there is a sticky paper or mucous membrane phenomenon.
    coating on the surface of the transferred substrate is not fully cured.
    d. thermal transfer glue quality is poor, ratio concentration and brushing amount is not proper, the normal heat transfer glue after a high temperature will automatically evaporate, leaving no traces.
    . If this is caused by the use of thermal transfer glue adhesive paper, it is recommended that the transferred substrate be scrubbed clean with water or sent to the oven for brief baking to remedy.
    f. If the use of thermal transfer film caused this phenomenon, it is recommended to use low concentrations of acetone and other organic solvent scrub to remedy.
    (3), the product surface color is not uniform
    a. transfer paper (film) and aluminum surface is not close, when baking transfer paper up, or vacuum when the tube bag has leakage phenomenon.
    b. The temperature field inside the oven is uneven.
    c. substrate into the oven time is different, resulting in some parts of the substrate surface transfer time is too long.
    d. transfer film coating, glue coating is not uniform, the emergence of "flying glue (polygel)" phenomenon, so that the transfer paper can not be completely close to the aluminum profile.
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