Talc in plastics

Wollastonite is not yet used in commercial WPC materials, but it is currently under investigation to further enhance the properties of WPCs. The mineral is used worldwide in many plastic applications providing improvement in stiffness, impact, scratch resistance, lower thermal coefficient of expansion-contraction, and flame retardancy. The unique morphology of wollastonite and the variety size grades available can provide benefits that are not obtained by other minerals. In a number of cases, wollastonite has successfully replaced talc in plastic applications where further improvements in properties such as greater strength and improved scratch resistance were required. 

Talc in plastics, technical bulletin. RioTinto Minerals 2007. 

Table 12.4 Primary and secondary benefits of talc in plastics.

Only about 360,000 tonnes of mineral filler of any sort are used in polyolefins. Most of it is either calcium carbonate or talc. Globally, talc has 7% of the fillers-for-plastics market, and China is the world s largest producer. Consumption of talc in plastics is mainly in PP, but there is also considerable demand from the coatings, paper, pharmaceuticals, agricidtmal and water treatment chemicals sectors, as well as for ceramics and refractories. Estimates of consumption depend considerably on which minerals are counted some estimates have put global production at 2.4 M toimes in 2002, for all purposes. 

Many of the mechanical and other properties of plastics can be considerably improved by the incorporation of reinforcing agents in their formation. The incorporation of fillers such as clay or talc in plastics formulation can also have beneficial effects on the properties of plastics. 

Luaenac America. Inc. Talc in Plastics Products and Applications ... 

Interaction of Solids With Flotation Reagents. For flotation to occur with the aid of reagents, such compounds must adsorb at the sohd—hquid interface unless the soHd to be floated is naturally hydrophobic. In this latter case only depression can be attempted by the use of additional ions or depressants that hinder bubble—particle adhesion. Frothers (typically long-chain alcohols) and/or modifying agents such as hydrocarbon oils can, however, be used to enhance the collection of naturally hydrophobic soflds such as M0S2, talc, or plastics. 

The market for talc in the United States based on the 1995 U.S. Geological Survey Annual Review (3) is summarized in Table 2. Ceramics was the biggest market, having almost 35% of the total, followed by paint, paper, and plastics. Outside of the United States, especially in Asia, paper is the principal apphcation. In that region talc is available locally at lower cost than competitive minerals such as kaolin. 

In electrical porcelains (often called steatite bodies), high purity talc products with low levels of alkali metals ate preferred. A typical steatite is made from 85% talc, 10% plastic kaolin, and 5% BaCO. Steatites ate used as insulators on high voltage equipment such as automotive starters, microwave oven generators, and laser generators. 

Radosta JA, Trivedi NC (1987) Talc. In Katz HS, MUewski JV (ed) Handbook of fillers for plastics. Van Nostrand, New York, p216... 

In plastics, the addition of talc improves their heat distortion temperature, dimensional stability, scratch resistance, impact resistance, and reduces the process cycle due to nucleation. Other important properties include high brightness, blocking of infrared in agricultural film, anti-blocking properties, and low absorption of packaged components. 

Minerals, such as calcium carbonate, talc, silica, are quite common fillers in plastic industry. They, often at abont 6-15 cent/lb, replace a much more expensive plastic, increase stiffness of the filled product, and render the plastic more flame resistant. The world filler market for plastics is dominated by carbon black and calcium carbonate. Of abont 15 billion pounds of filler in America and Europe, about half the filler volume goes into elastomers, a third into thermoplastics, and the reminder into thermosets. About 15% of all manufactured plastics contain fillers. 

The most remarkable effect of talc on plastics is the increase of stiffness. In general, the flexural modulus of a polyolefin increases by 150-200% with every 20% of talc added. The more platy the talc particles, the greater the effect. 

O. Noel and R. Clark. The use of talc in wood-plastic composites. In Progress in Woodfibre-Plastic Composites, Canadian Natural Composites Council University of Toronto, Canada, Toronto, 2004. 

Talcum (talc, 14807-96-6) is a natural hydrous magnesium silicate that can be associated with deposits of crude asbestos. Industrial talc, used extensively as a filler in plastics, cosmetics, coatings, lubricating compositions, and polishes may contain or be strengthened with up to 2 particles per 100 of asbestos fibre. 

Mineral fillers such as mica, kaolin, calcium carbonate, and talc are frequently incorporated in thermoplastics to reduce the costs and improve the properties of the polymers such as rigidity, durability, and hardness [30]. Talc is common filler in plastics as it serves as the most cost effective filler. Previous researchers have... 

Several techniques have been developed to rapidly identify additives in plastics as part of an overall plastics recycling operation. Some techniques such as Fourier transform infrared (FTIR) can combine resin identification with information of the presence or absence of additives such as flame retardants or talc fillers [49, 62, 65]. The sliding spark technique developed at the University of Duisburg in Germany can identify a range of heavy metals along with the type of resin [68, 69]. 

Rio Tinto Minerals is responsible for 25% of the world talc production and is the largest producer in North America with largest mine in Montana. Its total production increased from 1.26 million tons in 2000 to 1.33 million tons in 2002 following the acquisition of the Three Springs mine in Austraha [12]. Production for 2007 was around 1.28 million tons affected by the slow housing market [13]. Major talc suppliers and grades recommended for use in plastics are listed in Table 12.3. 

Talc is also recognised as a filler in plastics for sound and vibration absorption in the construction industry. Nanotalcs are being developed for use in automotive applications. 

Thermoplastics represent more than 80% of all plastics manufactured. Of these, the four major commodity plastics PE, PP, PS and PVC represent nearly 75% of all synthetic polymers produced annually, or about 75 million tons worldwide. Filled thermoplastics represent a huge and growing market for all types of manufactured products. It is estimated that each year 20 million tons of fillers are used in plastic materials. Currently, the most important fillers are calcium carbonate, talc, silica, mica, clay, aluminium trihydrate, glass fibres, starch and cellulosic powders. 

The most important mineral fillers used are carbonates, clays and talcs, while other silicates are also of interest. Several carbonate minerals are known with some having potential for use as mineral fillers, although only a few are of industrial importance in plastic and rubber applications. 

Minerals and other particles are used as fillers in plastic moldings either to enhance mechanical properties or to reduce shrinkage and flammability. The minerals and other particles used as commercial fillers are mica, clay, talc, silica, woUastonite, glass beads, carbon black and calcium carbonate. Theberge [331] summarized... 

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