Preparation Of Emulsifier-free Emulsion Of Vinyl Acetate Copolymer And Its Application In Humidity Controlling Coatings

With the development of science technology and improvement of peoples’ livingstandard，the roles of coatings are gradually developing from pure protective anddecorative functions to special and intelligent functions. Moreover, the preparationmethods of the smart coatings mainly depend on polymers, pigments and functionalfillers, and special technology. Meanwhile, the relative humidity of indoor air is animportant parameters in human health, and in the working and living environment, andit would effect on our normal work and life when it too high or too low. Therefore, howto controlling indoor relative humidity become an important subject in too dry or toowet environment. The object of this theme is a series of coatings which has goodperformance and could automatic humidity controlling automatically were preparedbase on the preparation of copolymers emulsion and humidity controlling coating ofour research group. Functional monomers were added the process of preparation ofpolymers emulsion, which has functional film-forming properties, inorganic porousmulti-layer material as pigments and fillers, were applied the wall coatings withhumidity controlling functions. The water absorption of coatings improved under theimportant precondition which ensure the basic performance of coatings. And thewater-sensitive breathable coatings have the performance keeping the environmenthumidity and are a kind of the coatings with environment-friendly coating. It will beused in this field widely.The progress research of emulsifier-free emulsion polymerization and the structure,properties, application of the attapulgite was reviewed, and mainly its application in thefield of polymer materials. This theme is divided following parts:1) Firstly, Vinyl acetate was introduced into emulsion polymerization as functionalmonomers because vinyl acetate was cheap and hydrophilic better, and vinyl-acrylatecopolymer emulsifier-free emulsion (EF-VA) was prepared. Moreover, the effects of theinitiator content, the reaction temperature and the content of functional monomer on the stability of this system were investigated. Furthermore, the structure of copolymeremulsion was characterized by FT-IR spectra, and the thermal stability of copolymerwas investigated by thermogravimetric (TG) analysis technology. The results showedthat vinyl acetate was introduced and successful polymerization. And the morphologiesand particles size of emulsion observed by TEM and DLS. The water-sensitivebreathable coatings (EF-VA-C) were prepared with copolymer emulsion asfilm-forming material and fillers of bentonite, montmorillonite, kaolin, attapulgite claythat was used at the first time. And its water absorption and humidity controllingperformance were tested.2) Moreover, the vinyl acetate-maleic anhydride emulsifier-free copolymeremulsion (EF-VAc-MA) was synthesized with vinyl acetate, maleic anhydride andbutyl acrylic (BA) as the mainly monomers. The effects of the reaction temperature, thereaction time and KPS amount on process stability and the system stability wereinvestigated. The effects of MA and neutralizer amount on the conversion rate andsystem stability were discussed. The structure, thermal stability, morphology and thedistribution of particle size of copolymer emulsion were observed by FT-IR, TG, TEMand DLS respectively. The film-forming properties, adhesion and water absorption ofthe copolymer emulsion was also measured. The water-sensitive breathable interiorwalls coatings was prepared by emulsifier-free copolymer emulsion, ADH as crosslinking agent, pigments and fillers. The results showed that: the basic performance ofthe coatings were meet national standards (Standard No.: GB/T9756-2009) of syntheticlatex using interior wall coatings, and its water absorption, water resistance andhumidity controlling performance are well.3) Finally, the styrene-maleic anhydride emulsifier-free copolymer emulsion(EF-VAc-MA) was synthesized by styrene (St), maleic anhydride (MA) and butylacrylic (BA) as the copolymerization monomers. The effects of the reactiontemperature, the reaction time and neutralizer amount on particle size, conversion andthe system stability were investigated in the system. The structure, thermal stability,morphologies and the distribution of particle size of copolymer emulsion were observedby FT-IR, TG, TEM and DLS respectively. The film-forming properties, adhesion and water absorption of the copolymer emulsion were also measured. The water-sensitivebreathable interior walls coatings(EF-St-MA-C) was prepared with emulsifier-freecopolymer emulsion, ADH as cross linking agent, attapulgite, bentonite, diatomite,titanium dioxide as pigments and fillers. The coatings structure and microscopicmorphology was observed by SEM. The coatings water absorption of differentpigments and fillers ratio, color of attapulgite clay, material plates and humiditycontrolling properties.In conclusion, the humidity controlling coating has excellent water absorption,water resistance and humidity controlling. Furthermore, its preparation technology,construction measures are simple and easily, and it have features of safety,environmental protection, energy-efficient, so the coatings will be used widely.