Fillers hiding power

Optical. The optical properties of fillers and the influence that fillers have on the optical properties of filled systems are often misunderstood. The key parameters in understanding the optical properties of fillers themselves are filler psd, color, and index of refraction. These characteristics influence the optical properties of filled composition, such as color, brightness, opacity, hiding power, and gloss. 

Fillers are used frequently with solvent vinyl systems in order to lower cost. Increase hiding power of the coating, and increase the total solids of the system. They may detract from ultimate durability due to impurities that are present in the filler. This may manifest itself as poor light stability or film porosity due to water-soluble ingredients present. Basic ingredients may be reactive with carboxyl-containing (metal adhesion type) resins. Iron contamination may cause poor light and heat stability of the system. 

Sometimes, the intermediate coat is overcoated with the topcoat in a wet-in-wet system. Normally, however, two-pack polyurethane topcoats are applied to the dried filler. These topcoats with aliphatic isocyanate hardeners have excellent gloss and color retention. The DFT of topcoats is 40 - 80 pm, depending on the hiding power of the topcoat. 

Chem. Descrip. Aluminum silicate, thermo-optic CAS 1327-36-2 EINECS/ELINCS 215-475-1 Uses Pigment for paint formulations, paper coatings reinforcing filler for plastics, rubber, water and solv. systems Features High hiding power U.S. patent 3,021,195 Properties Wh. thin flat plate 0.15% max. on 325 mesh sp.gr. 2.2 oil absorp. 73 ref. index 1.62 pH 4.0-4.5 0.5% max. moisture Toxicology Nontoxic Titankup [Malvern Mins.]... 

In addition to pigments a series of extenders or charges are introduced in the paint manufacturing process. Extenders have a poor hiding power and are more economical than pigments, and these products can be used as fillers to introduce modifications in the final characteristics of the paint, such as to modify the thixotropic behavior of the matrix or to reduce... 

The hiding power of a polymer surface is related to inhomogeneities (such as fillers or more than one phase) that cause strong reflections. 

Titanium dioxide is by far the most effective white pigment a compounder can use in a rubber compound. It has superior opacity, brightness, and hiding power over all other white pigments or fillers. However, it is also more expensive than other white fillers such as special water-washed clays, calcium carbonate, and talcs. Occasionally, organo-titanates are used in rubber formulations to improve filler dispersion, that is, the compound s rheology. 

Titanium dioxide is used in rubber compounds to impart a white appearance. It is sometimes the preferred pigment because it possesses a great deal of hiding power because it has a higher refractive index than any other rubber filler available. 

Titanium dioxide has the most hiding power and opacity compared to any other commercial filler used today. Some rubber compounds need a filler with this level of hiding power to achieve the desired appearance. 

In aqueous systems, the hydrophilic nature and low water demand enable the easy incorportion of high levels of calcium carbonate with only minor increases in viscosity. Calcium carbonates are normally used in conjunction with other fillers and titanium dioxide to enhance the dry hiding power and rheological properites of the paint system. The optimum particle size range for ground natural filler grades of calcium carbonate in coatings is 3 to 7pm. 

Fillers cause significant deadening of the adhesive, which can be compensated again by a slightly increased amount of tackifier. In labels made from relatively thin paper, small amounts of fillers or pigments can be added in order to increase the hiding power. 

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