Redispersible polymer latex powder is a new type of powder functional material obtained by drying polymer emulsion , It is characterized by being redispersible in the aqueous phase to form a dispersed emulsion having similar properties to the original emulsion. Compared with traditional lotion , The dispersible polymer powder has the advantages of convenient construction, stable storage, easy transportation and environmental friendliness. , And can significantly enhance the cohesion and flexibility of inorganic building materials , Has broad prospects for development. Redispersibility is the core performance of latex powder , But its formation mechanism is not clear , Research related mechanisms have important theoretical guiding significance for the development and performance optimization of polymer powder materials. Methyl methacrylate (MMA) Styrene (St) ,Methacrylate (MAA) Polymer emulsion with core-shell structure and spray drying to obtain polymer latex powder , , Preparation of water resistant NMA- Styrene-propylene redispersible latex powder. The main research results of this thesis include : 1) Rejection of the stability mechanism. Shell ionizable hydrophilic monomer MAA Conducive to the formation of latex particles " Fluff structure †And thick hydration layer , Enhanced drying protection , Simultaneously increase the surface charge density of latex particles , Enhanced charge repulsion , The redispersibility of the latex powder is then optimized. 2) Diffusion strengthening mechanism. Emulsion drying can be summarized as 3 Steps :(1) The surface of the emulsion droplets is dried to form a wrap layer ;(2) Latex inner layer drying , The hydration layer evaporates and expands to form micropores ;(3) The pore size is enlarged until a continuous channel is formed. When the latex powder is dispersed in the water phase , Moisture enters the interior of the latex powder through the micropores to accelerate its dispersion , The micron-sized latex powder is dispersed into nano-sized original emulsion latex particles. 3) " Fluff structure †And hydration layer generation , Reduce surface charge density and hydrophilic group density , Irreversible agglomeration fusion when latex particles dry ; When the latex powder is dispersed in the water phase , Hydrophobic association reduces water osmotic pressure, polymer chain charge repulsion and hydration , Water dispersibility and dispersion stability are deteriorated. 4) Produced with both water dispersibility and water resistance of the film NMA- Styrene-acrylic latex powder and dry powder architectural coatings. Its best synthetic formula is : Shell MAA Amount of monomer 6 %; Shell St/ MMA Mass ratio is 5/ 25; Add emulsifier and NMA The amount of monomer is 0.33 % with 1 %, Spray emulsion pH Value 8.5 . The preparation of polymer latex powder and redispersion of water phase is a process of competition between hydrophobicity and hydrophobic association. , Repulsive stability and enhanced diffusion of microporous channels are the main reasons for the dispersion of latex powder water.
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For the development of a redispersible latex powder emulsion? Considering the water dispersibility of latex powder and its film-forming water resistance
For the development of a redispersible latex powder emulsion?
Polymer hydrophobic association inhibits latex particles