Temperature requirements for various coatings in the spray line
In the spraying production line, there are many links to control the temperature, such as preheating, drying and curing, etc., because the coating must be adhered to the workpiece at a certain temperature to achieve the effect of protecting the workpiece. So, what are the specific temperature requirements for different coatings used in different industries? Come and find out with me!
(1) baking paint
Baking paint is divided into two categories, one type of low temperature baking paint curing temperature is 140 ° C -180 ° C, the other type is called high temperature baking paint, its curing temperature is 280 ° C -400 ° C high temperature baking paint. Usually, the baking temperature is generally 160-220 ° C, but due to the thin film, the heating time is short, so the phosphating film can guarantee its integrity.
(2) Powder coating
A thin coating of 200 um can be obtained by using a thin electrostatic spray coating (typically 20-60 um), an electrostatic fluidized bed, a fluidized bed, and the like. Due to the poor melt flowability of the powder coating, in order to achieve an appearance smoothing effect. For thick coatings, it is necessary to increase the heating temperature (generally higher than the melting point of 50 ° C) and prolong the heating time, which is likely to cause a decrease in the bonding strength of the coating and even a peeling phenomenon of the coating.
(3) fluororesin and composite coating
Polytetrafluoroethylene (PTFE, F4) has poor melt flowability even at a high temperature of 380 ° C, and a non-porous coating cannot be obtained, and a coating having a high bonding strength cannot be obtained by phosphating.
Early non-stick pan: lint processing, wooden shovel cooking. The 2004 China Consumer News has not been used (decomposed carcinogens). At present, it is basically useless and is not suitable for Chinese cooking methods.
Tetrafluoroethylene-hexafluoropropylene copolymer (FEP, F46), which has the property of thermoplastics, can be used to prepare a dense coating by heating at 300 ° C for 15 min. The disadvantage is that the bonding strength is low - not sticky. The high heating temperature is prone to failure of the phosphate film, and sometimes the phosphating is not as good as the direct coating after pickling. In short: Phosphating is not suitable, mechanical coarsening, chemical roughening, preparation of porous (ceramic) transition layer, cold spray primer and so on.
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