Opacifying pigment

Use. Lithopones are used in water-based paints because of their excellent alkaH resistance, in paper manufacturing as a filler and opacifying pigment, and in mbber and plastics as a whitener and reinforcing agent. 

The RI of any material (primary or secondary pigment) is a key to its performance. As is well known, the larger the difference in RI between the pigment and the medium in which it is dispersed, the greater the opacity effect. A summary of the refractive indices of various extender and opacifying pigments is provided in Table 18.1. 

Fillers must be free of sulfur-containing impurities, iron, and zinc. In order to minimize reduction in clarity, fillers should have a fine particle size and an index of refraction close to that of the PVC resin. If opacity is desired, however, high refractive index fillers such as talc or calcium carbonate can be used to minimize the amounts of the more expensive titanium dioxide opacifying pigment required. 

Amerlate . [Amerdiol Amerdud Europe] Lanolin acids and esters emulsifier, stabilizer, emdlient, conditioner, moisturizer, lubricant opacifier, pigment dispersant wetting agent fv cosmetics, pharmaceuticals, wax systems, household prods. 

Chem. Descrip. Rutile titanium dioxide CAS 1317-80-2 EINECS/ELINCS 236-675-5 Uses Opacifier, pigment in paper coatings, coated and uncoated printing and writing papers, paperboard, saturating papers Regulatory DOTnonregulated SARA 311/312 nonreportable CERCLA nonreportable... 

With rigid PVC products used in exterior building applications, approximately 9-13% of rutile titanium dioxide is often nsed as an opacifier pigment. The pigment absorbs incident UV radiation shielding the bulk polymer from exposure. Organic UV absorbers such as benzophenone or benzotriazoles compete with the chromo-phores in the plastic in absorbing radiation. For instance, benzophenones reversibly isomerize in the process. 

Table 4.1 Refractive indices of various extender and opacifying pigments.

Antimony oxide is also a brilliant white opacifying pigment with a pink undertone. However, it is much more expensive than titanium dioxide and finds httle use for this purpose. 

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