Common defects of PVF coating film and prevention methods thereof
Qingjiang Metal Container Factory Wang Shoushan
PVF coatings are special coatings for the synthesis of fluorine-containing organic polymers. The physicochemical properties of the coating are particularly excellent: it has good adhesion to metal materials, high hardness of coating, good toughness, abrasion resistance, impact resistance, chemical corrosion resistance, non-toxicity, good three-proof performance, and is called a A bake-type facing material is sprayed in a steel drum with ideal performance.
Since PVF coatings can only be plasticized into film after baking at a certain temperature, baking is a key part of the physical change process. In order to make everyone use PVE coatings, the list of common defects and their causes and prevention methods for baking and film formation are described below for reference:
No. Bad condition Cause Prevention method 1 Coking The temperature of the drying tunnel is too high. The film is decomposed. Lower the temperature and release the drying tunnel in time. 2 Membrane soft Multi-spray (over-thickness), difficult to evaporate residual solvent Check paint and spray gun to prevent multi-spraying and sagging, and prolong the baking time. 3 Slag coating dilution or multi-spray (barrel rotation difference) Check paint, spray gun, adjust the amount of spray to prevent multi-spray (roller wear replacement) 4 pitting (skin), water ripple spray gun pressure is too large, (the spray gun is close), Check the gun air pressure and distance too much in one shot. Appropriate adjustment to prevent over-spraying at a time. 5 Stripping. Poor surface treatment. Residual solvent surface treatment is handled according to PVF coating process requirements (one of the key processes), increasing the drying tunnel temperature or prolonging the baking time. After repairing the surface, apply it in time. 6 Color difference The temperature of the drying tunnel is uneven, and the wall thickness difference of the barrel is checked. The temperature of the drying tunnel is checked to accelerate the rotation of the barrel, so that the thick wall is heated by radiation. 7 Pinhole Coating spray is too thin and uneven Check the spray amount and re-spray once (or partial fill) 8 Blank spots Surface treatment is oily, water droplets are not dry. The surface should be oil-free, rust-free, dry, etc. The repair is erased with alcohol (or gasoline) and applied. 9 Curving The initial drying tunnel temperature is low. Check the degree of drying. The temperature is not enough to put into production. 10 疙瘩 coarse grain paint is uneven, the paint has coarse particles. When the paint is diluted, stir well. The coarse particles were filtered through a 180 mesh sieve. 11 Membrane dust spots Drying dust in the drying tunnel Check the dust in the exhaust duct.Note:
(1) The plasticizing film forming baking temperature is controlled at 230-280 ° C, and the ingress and elapse time is 20-30 minutes.
(2) Spraying is generally performed once at a time, and the film formation (mass) is best by secondary two-time baking, and the film thickness is generally about 40 μm.
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