| In this paper, a serious of low-temperature polyester/epoxy powder coating made up of polyester, epoxy (E-12) as the main curing body in addition to filler and other additives were prepared by melt blending method. The effects of the kind and amount of polyester resin, kind and amount of filler on polyester/epoxy powder coating film coating appearance, pencil hardness, adhesion and impact strength were investigated, and discussed the influence of curing catalyst 2-methyl imidazole (2-MI) dosage on curing properties of powder coatings and film performance by the FI-IR. and DSC, the amount of 2-MI was determined. The curing reaction of the powder coating was studied using non-isothermal differential scanning calorimetry, through kinetic analysis we can obtain the parameters of curing reaction such as theoretical curing temperature, on the basis of theoretical curing temperature, we can obtain optimal curing time and curing temperature by coating the powder coating at different conditions. We select the optimal polyester/epoxy powder coating formulation for flame retardant performance; ultimately determine the optimal amount of flame retardants by measuring the impact strength and the flame retardant performance of after solidification powder coating. The following conclusions:(1) Through the experiment to determine that polyester resin P5127, filler of precipitated barium sulfate, curing accelerator of 2-methyl imidazole for low temperature curing of polyester/epoxy powder coating was better.The content of precipitated barium sulfate can reach 25%,2-methyl imidazole can effectively reduce the curing temperature, decrease the coating curing temperature from 170℃ to 150℃, low temperature curing was realized.(2) The amount of 2-methyl imidazole was 0.4 g, the system of the curing temperature was relatively low, and has improving performance such as the appearance of the coating, impact strength etc. Analysis the curing kinetics of polyester/epoxy powder coating with 2-methyl imidazole as curing catalyst, it was concluded that when the amount of 2-methyl imidazole was 0.4g, the curing reaction activation energy was 9.325 kJ/mol, reaction series n was 0.95, the frequency factor A was 9.83×102, curing reaction kinetics equation: Polyester/epoxy powder coating had good practical curing condition was:150℃,30 min or 140℃,20 min.(3) For three types of flame retardant such as magnesium hydroxide, zinc borate and Halogen-free flame retardant, when joining the quantity was small, Halogen-free flame retardant which effected on impact strength of the powder coating film was minimum, flame retardant effect was optimal. With the increase of the filling dosage, the performance of flame retardant of powder coating gradually improved, the impact strength gradually redeced. The optimal dosage of halogen-free flame retardant was 40%, the impact strength of polyester/epoxy powder coating film was 40 kg·cm, oxygen index was 28.0%. |
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