Similar to solvent-based coatings, when the temperature of the construction environment is high, the volatilization rate of water is fast, and the coating is not fully wetted on the surface of the substrate, and the film is dried before leveling, resulting in poor appearance of the coating film.
When the temperature is low, the evaporation rate of water is slow, and the coating film is easy to appear hanging.
Therefore, compared with solvent-based coatings, the construction temperature range of water-based coatings is relatively narrow, and strict control of the construction temperature of water-based coatings is necessary to ensure the appearance of good coating film.
Macromolecular Azo Initiator
According to the synthesis method, macromolecular azo initiators are divided into poly azo carbonate, poly azo esters and poly azo am in des.
Polyazocarbamate is prepared by reacting a prepolymer fischer tropsch wax density formed by the reaction of polyether glycol and dibasic isocyanate with azo glycols, and the structure is shown in formula (4-40).
CH: CH, OO
+(C Hz) :-C-N-N-C-(CH 2) .OC-NH(R-NHC-O
Polyurethane is prepared by the reaction of azodiacid chloride and polyether glycol, and the structure of the polyethylene glycol azo macroinitiator is shown in formula (4-41).
Polyazamide is produced by the reaction of a, w-dichloride of azobisisobutyronitrile and diamine. For example, in the presence of a small amount of azochloride, decyl (or adipic) dichloride and hexamethylene diamine are produced by interfacial polycondensation. Polyazoamide, the structure is shown in formula (4-42).
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