Titanium dioxide opacity

White Pigments. Opaque white pigments commonly used in inks, in order of decreasing opacity, ate titanium dioxide and zinc oxide. TiO is by fat the most popular white pigment. Mixtures of whites ate often made with the various colored pigments to add opacity or to make pastel colors. 

Gels. Amorphous hydrated silicas of a purity and stmcture typical of those used ia type 1 dentifrices and the liquid portion (humectant system) of type 1 dentifrices both have approximately the same refractive iadex, ie, about 1.47. As a result, the type 1 dentifrices represented ia Table 1 are inherently transparent or translucent. In the marketplace it has become popular to refer to such dentifrices as gels. For marketing reasons some companies have chosen to opacify these products, with titanium dioxide, for example. The opacified products are identical ia functionality, stmcture, and all other ways, except opacity, to their translucent or transparent counterparts. 

To opacify the adhesives. Opacity is required for aesthetic reasons or as an indication of how uniformly the adhesive is applied. Titanium dioxide is used to make the adhesive opaque. 

Amount if too little titanium dioxide is added, the distance between particles is too large and there is not enough opacity, while if the titanium content is too high, the particles interfere with each other and poor efficiency is obtained. 

In the 1970s, textbook publishers (and other entrepreneurs) found that adding titanium dioxide to paper as a filler and whitener enormously increased its opacity (Figure B). This allowed for the use of thinner paper without having the type "bleed" from one side to the other. Perhaps this explains, at least in part, why most chemistry textbooks today (but not this one) run to a thousand pages or more. 

The refractive index of these pigments is about 1.5, which means that they give a transparent blue when used in paints and clear plastics. Opacity can be increased by adding small amounts of titanium dioxide. The principal failing of ultramarine is its lack of resistance to acid, which can even decompose the pigment if there is sufficient available. Coated grades are made with substantially improved acid resistance. 

Many inert pigments (often known as fillers) are incorporated into paper in addition to the cellulosic fibres. They may be added to improve certain optical properties—in particular opacity and brightness—or simply as a cheap replacement for costly fibre. The two most common pigments are kaolin (china clay) and chalk (limestone), but talc and speciality pigments such as titanium dioxide are also used. The particle size for general purpose fillers is normally expressed as an equivalent spherical diameter (esd) and this is determined from sedimentation data. Values for the common paper-... 

When the product is a solid, such as titanium dioxide used as an additive to paint and to paper to improve opacity and covering, the descriptive parameters also include the crystalline and amorphous nature of the solid, the average diameter of the crystals,... 

Pigments such as titanium dioxide (n = 2.5) with n values which are higher than that of the polymer are effective opacifiers. The opacity is also related to the size of the pigment particles. 

Opacity -of inorganic pigments [PIGMENTS - INORGANIC] (Vol 19) -of titanium dioxide [TITANIUM COMPOUNDS - INORGANIC] (Vol24)... 

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