Problems in the drying and curing of coatings

1, curing:coating curing and drying control is to achieve the best performance of the coating film is importantIn many cases, it is experience, visual inspection and testing for curing controlUsually we should pay attention to the curing of inorganic zinc silicate coatings and other two-component coatings using curing agents(1) Inorganic zinc silicate coatings require moisture to help cureIf the relative humidity is less than 60%, curing becomes slowIn order to cure quickly, high relative humidity and temperature are requiredSufficient relative humidity can be added within a few hours of constructionThe fastest and best curing effect is the use of hot steamThe curing state can be tested using MEK reagents (methylethyl)With white cotton cloth meK reagent, wipe the coating surface, if only a little color or no color color, indicating that the coating has been curedBecause inorganic zinc silicate coatings are solvent resistant after curingThe method is shown in standard ASTMD4752-87(2) two-component coatingSuch as epoxy coatings, polyurethane coatings and polyester coatings, curing depends on temperatureThe coating surface can be wiped with a solvent or a stronger solvent to detect good curingIf the coating film has been cured, the coating surface will not be affected 2, wrinkle: film wrinkles usually occur in oily coatings, alkyl paint sour paint and phenolic coatings For example, the surface of flax oil expands by absorbing oxygen from the air, causing unoxidized paint body to wrinkle on the surface These coatings are usually added with a desiccant to speed up drying Some are used to accelerate surface curing, others are used for uniform drying from bottom to surface If the coating contains too much surface destruator, wrinkles may occur where the coating is thick Cobalt salts are commonly used as surface severs, zinc and lead compounds used as dry permeants temperature on the wrinkled effect is quite large, at room temperature can not wrinkle the paint, in the baking with the temperature rise, the surface curing is much faster than the body curing, there will be a serious wrinkle In the colder temperature of the construction of a hundred thick film-type paint, or in the hot sun, the rapid drying of the paint, the humidity of the primer, etc., are causing wrinkles