Principle of the hiding Air void Micro bead which has air void at the inside like Fig 1 has opacity by itself by scattering light effectively. Fig 2 shows the principle of scattering. The chief ingredient of shell in this micro bead is poly(styrene) and its refractive index is about 1.59 which is similar to the refractive index of paint's binder. These air voids and non-pigmented emulsions are both transparent to light, but they have different refractive indices(CA. 1.0 and 1.5 respectively). These difference provide light scattering effect and opacity in the dried film of the emulsion paint. Among the composition of the water base paint, Titanium Dioxide is one of the most effective component to providing the Opacity/Hiding power of the paint film and the incorporation of extenders increase the paint PVC. When the PVC of paint is higher than CPVC in water paint, air void is possessed in the dried paint film and this air void increases opacity of the film. Generally, from economic standpoint, paint formulator would like to incorporate as much as air in the paint film as possible, but highly porous paint film has poor integrity, and abrasion resistance and other properties. The SYNTHETIC micro-polymer beads of opaque polymer HIQUE are completely spherical and uniform in nature and the particle size is well controlled compared with other 'Natural' pigments and has encapsulated air void is also well defined. Therefore, incorporation of opaque polymer HIQUE in emulsion paints has the effect of reducing the total surface area of the hiding components. Thus encapsulated air voids in the opaque polymer HIQUE increase the opacity of the paint film and less negative affects the other properties of dried paint film such as resistant properties, scrub resistance etc. Anticrowing effect Formulation of water based paints with PVC's below critical level contain so much titanium dioxide that the pigment particles tend to become packed or "crowded" together. In case of paints above the CPVC, the formulation contains less TiO2 than low PVC paints. Although crowding may still occur between the pigment components of the emulsion paint, Titanium dioxide has a much smaller particle size than other extenders.(e.g. calcium carbonate, clay etc.). In the dried film, Titanium dioxide particles tend to become crowded together and interfere with each others ability to scatter light and consequently hiding power is greatly reduced. Incorporating HIQUE 821 opaque polymer in water base paints together with well dispersed Titanium dioxide, will give a greatly reduced crowding effect, thereby, enhancing the opacity of the paint.
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