| Alkyd coating is a synthetic resin coating which uses alkyd resin as a mainfilm-forming substance, and its application is very extensive. To reduce the viscosityto meet construction standards, large amounts of organic solvents are added during theproduction of alkyd and alkyd paint, leading to the problem of VOC (volatile organiccompounds) emission. It is urgent for environmental protection to find ways to reduceVOC emission from the coating. Sucrose polyester (SPE) is an environmental friendlyproduct of P&G which is synthesized by the esterification of renewable esterifiedfatty acid and sucrose molecules. No organic solvent is added during the productionof sucrose polyester and its viscosity is quite low, thus requiring a small quantity oforganic solvents to make the coating with sucrose polyester as a component, whichcan effectively control the VOC emission. In this thesis, sucrose polyester was used asa binder to replace alkyd to make sucrose polyester alkyd coatings，includinghigh-solid sucrose polyester alkyd coating and water-borne sucrose polyester alkydcoating.In the preparation of high-solid sucrose polyester alkyd coating, the effect of thecontent of unsaturated bond of the sucrose polyester, the effect of dispersant on theperformance of pigment paste, the effect of substitution of sucrose polyester on filmhardness, drying time and VOC emission and the impact of drying agents on filmdrying performance were investigated. The coating formulation was finally optimizedand a series of coating performance were tested. The results indicate that: SPE andalkyd as a mixing binder can be used to make an eco-friendly high-solid coatingwhich has the properties of good film performance and low-VOC emission. Thefilm-forming property and the stability of the coating are optimum when chooseSPE1618U as the sucrose polyester in the experiment and BYK-P104as the dispersant and when the optimal amount of substitution of sucrose polyester is40%,the non-volatile content significantly increases while the VOC level decreases by60%to136g/L compared to the original alkyd coating. Meanwhile, the film hardness andthe drying time of film remain nearly consistent，and other properties of the coatingare superior or equal to the original alkyd paint. In sum, all those data indicate that thesucrose polyester alkyd coating is a product with a high ecological quality, whichfully meets the construction requirements.In the water-borne sucrose polyester alkyd coating system, factors affecting thestability of sucrose polyester alkyd emulsion such as the type of the emulsifier,emulsification method, the HLB value, the dosage of emulsifier and emulsificationtemperature were investigated and the optimum technological parameter was obtained.Then the hybrid surfactant-stabilized sucrose polyester alkyd emulsion was made intoa waterborne white paint formula and evaluated for a variety of properties comparedwith the original water-borne alkyd coating. The results indicate that the stability ofsucrose polyester alkyd emulsion is the optimum when emulsification method isemulsification by PIT and the emulsifier is TX-10, with a dosage of10%. Theemulsification temperature is70℃and the maximum replacement of sucrosepolyester is60%. And through experimental analysis and tests, a rutile titaniumdioxide R-706, pH adjusting agent AMP-95, dispersant BYK-191, nonionic thickenerRM-8W and RM-2020NPR, wetting agent CF-10and123aqua agent were chosen tomake water-borne sucrose polyester coating. The results also indicate that the hybridsurfactant-stabilized sucrose polyester alkyd coating has a higher ecological qualitythat the percentage of non-volatile matter content is larger while the VOC level islower when compared to the original water-borne alkyd coatings. In addition, theresult of rheological and storage stability curves and thermal storage stability revealsthat the water-borne sucrose polyester alkyd coating can satisfy the currentrequirements and has the stability of long-term storage. |
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