Pigments as fillers

As regular mineral fillers are, in general, lower in price than typical papermaking fibers, replacing fiber by mineral fillers usually provides better papermaking economics. Therefore, efforts are made to include as much filler in the paper as the technological demands can support. 

Overall, the wood-free uncoated paper grades mentioned are loaded mostly with primary (fresh) filler only. The coating base papers are filled with coating pigment 

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In addition to its mechanical stability, silica has the particular advantage of a low-cost and easy synthesis and a simple, inexpensive, and flexible means of surface modification. Furthermore, in contrast to, for example, polymeric materials, it is possible to synthesize silica with a specific and closely distributed pore size. This is an important point for optimization of the separation kinetics, thereby achieving narrow elution bands. Detailed iirformation about the preparation of silica, its characteristics, and chemistry can be found in the book by Isler [1]. In actual fact, chromatography is not the main use of silica, much more common is its use as a pigment, as filler in the cosmetic and plastic industries, and as an adsorbent and support for catalysts (keyword zeolites). 

Nacreous Pigments. Mica is used as a substrate for coatings (qv) of various metal oxides to obtain a peadescent effect. Mica coated in this fashion is used as filler and as a coloring agent in certain types of plastics. 

In recent years, synthetic polymeric pigments have been promoted as fillers for paper. Pigments that ate based on polystyrene [9003-53-6] latexes and on highly cross-linked urea—formaldehyde resins have been evaluated for this appHcation. These synthetic pigments are less dense than mineral fillers and could be used to produce lightweight grades of paper, but their use has been limited in the United States. 

White pigments such as calcium carbonate, aluminum hydroxide, silica, kaolin, or urea-formaldehyde resin are used as filler. The filler functions as an absorbent of melted components to prevent their adhesion on the thermal head. Thus, the filler is required to be high in oil absorption and not to wear the thermal head. 

Infrared spectroscopy is a major tool for polymer and rubber identification [11,12]. Infrared analysis usually suffices for identification of the plastic material provided absence of complications by interferences from heavy loadings of additives, such as pigments or fillers. As additives can impede the unambiguous assignment of a plastic, it is frequently necessary to separate the plastic from the additives. For example, heavily plasticised PVC may contain up to 60% of a plasticiser, which needs to be removed prior to attempted identification of the polymer. Also an ester plasticiser contained in a nitrile rubber may obscure identification of the polymer. Because typical rubber compounds only contain some 50% polymer direct FUR analysis rarely provides a definitive answer. It is usually necessary first... 

Cortes et al. [975] have used on-line p,SEC-CGC for rapid determination of a great variety of additives in an emulsion ABS-PVC blend, HIPS and a styrene-acrylate-ethylene rubber polymer. These systems are difficult to analyse, because of the high levels of insolubles such as fillers, pigments, or rubber modifiers. The additives were separated from the polymer fraction in a polymer/additive dissolution using p,SEC, and were... 

Emulsion polymer isolation gives polymers in the shape of tiny hollow spheres called cenospheres. The pure polymers are rarely used. They are generally compounded with a variety of additives such as fillers, plasticisers, lubricants, pigments and stabilisers to provide a variety of materials with differing physical, chemical and electric properties. 

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-... 

The interest in mineral-promoted organic reactions stems from the need to understand the fate of pesticides in soils and pollutants in sedimentary environments (8), petrogenesis (20-27), humification (19, 28, 29), the origin and evolution of life (1, 30), the use of clays as catalysts in industrial processes (31-37), in pharmaceutical applications (3), and as pigments and fillers in paper, plastic, and rubber (37). 

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