Core-shell Latex Film Formation And Its Film Studies

Core-shell latex has attracted much attention in coatings and adhesives in recent years. It is possible to design particle morphology with the development of theory on the morphology of latex particles. There are two phases in coated film formed from the core-shell latex. Proper phase structure can afford excellent properties. Film formation process of core-shell latex is more complicated than homogeneous latex due to the interaction between the two different phases. In addition, the film formation from the core-shell latex is influenced by many factors, such as composition, morphology, temperature etc. Therefore, study on core-shell latex film formation should be one of core-shell latex developmental tendency. In this paper, film formation process of core-shell styrene-acrylate latex was described. The factors affected the film formation were also studied. Moreover, the relationship between the phase structure change and properties of film was discussed.By reasonable design, composite latex of P(St-co-BA)/ P(MMA-co-BA) was synthesized by two-step semi-continuous emulsion polymerization under starved conditions. It was confirmed by TEM that the resultant latex had core-shell structure. Drying rate curve of core-shell latex was established by weight analytical method. The results show that there are three steps in drying process. The drying rate is constant during the first step, and it is free water evaporation step. The second step of drying belongs to the first falling rate period dominated by capillarity. The third step of drying belongs to the second falling rate period dominated by diffusion. Meanwhile, results also reveal that increasing temperature and reducing pressure can accelerate the constant rate of dying. Other factors, such as solid content, amount of functional monomer, film thickness, core/shell ratio etc hardly affect on constant rate of drying, but they affect the water loss of latex and other step rate of drying.It is found that particle morphology of composite latex has crucial effect on coated film. The film formed from P(St-co-BA)/P(BA-co-MMA) core-shell latex is much more advanced than both physical blending latex and polymer solution in...