Ultrafine calcium carbonate

Calcium carbonate (ultrafine) " 0.1-0.8 (increasing with particle size decreasing) ... 

Product content calcium carbonate ultrafine precipitated coated with 2.4-3.2% organic coating... 

The calcium carbonate industry is one of the most competitive of the industrial minerals industry. The market for fine products (97% <45 fim) is estimated to be between 5—9 million tons annually in the United States. The pricing is dependent on the grade which is determined by fineness, purity, and brightness it ranges from 30/kg for coarse materials to over 440/kg for some ultrafine coated or food grades (4). 

Surface treatment also improves adhesion to the polymer matrix and resulting physical properties. The combination of particle size and surface treatment is critical in the selection of precipitated calcium carbonate fillers to obtain desired properties. Often graded combinations of ultrafine precipitated CaC03 and larger CaC03 particles are used for optimum properties and value. 

Particle size is important and, for some applications requiring good weathering and impact performance (window profile), the ultrafine milled, high whiteness, natural version is normally used. To ease dispersion, the filler is usually coated with stearic acid. Coated ultrafine and precipitated calcium carbonates are claimed also to have a positive effect on impact properties in impact modified formulations (52, 294, 462). The abrasive wear of calcium carbonate, on melt processing equipment, is not significant but increases with increasing levels (177). 

Ultrafine Calcium Carbonates 8.14, 8101 particle size 0.2-1.4 pm produced with (C) and without stearate coating... 

In trade sale coatings, plastic pigments and microvoids will be directly competitive with ultrafine particle size natural calcium carbonates and "thermooptic" calcined clays. It is probable, however, that the future will see greater rather than less emphasis placed upon the fire retardancy of architectural coatings, and the flammability of the plastic products may prove to be a deterrent to their widespread use, as has been true of plastic wall panels. 

Supercoat . [ECC Int l.] Surface-treated, ultrafine ground calcium carbonate for paper, plastics. 

Besides mixing different polymers, there are other possible ways to obtain high-impact plastics, for example copolymerization and graft polymerization or use of plasticizers in brittle polymers. These products will not be treated in this section. In the case of PVC-U, addition of ultrafine precipitated calcium carbonate (grain size 75 nm) has excellent impact cmiditioning and surface quality-enhancing effects. 

Polypropylene (PP500P, SABIC) has melt flow rate of 3.1 (2.16 kg at 230 °C) and density of 905 kg/m3 was used as matrix resin. Nano-sized synthetic ultrafine surface treated precipitated calcium carbonate (Socal 312, Solvay, France) with mean particle diameter of 70 nm used as filler phase. PP-g-MAH compatibiliser (Priex 20097, Solvay, France) with a maleic anhydride content of 0.05 wt % and MFI of 15 (2.16 kg at 230 °C) was employed to promote the interfacial interaction between nano-CaC03 and PP, and to extend the dispersion of nanoparticles in polymer matrix. Compounds used as processing materials are listed in the table 1. 

Calcium carbonate is also used to manufacture NR composites because of its low cost and performance at high loading level. Cai et al. prepared NR latex films reinforced with ultrafine calcium carbonate by solution mixing. They found that calcium carbonate was well dispersed in the NR latex. It was found that the tensile strength, modulus and tear strength of NR composite films were improved by a relatively low loading of calcium carbonate (15 wt%). 

Recent modified grades of calcium carbonate (from ECC International) include an ultrafine stearate-coated grade made from pure Italian marble, giving high whiteness in rigid PVCs and optimization of the cost-performance of titanium dioxide. 

Calcium carbonate is used in many rubber and plastic applications, mainly to reduce cost, but ultrafine grades, especially when stearate coated, can give technical advantages, for example, in polypropylene (PP) mouldings, nnplasticised polyvinyl chloride (PVC) extrusions and polysulfide sealants. 

The ultrafine materials are all semi-reinforcing in character, as a consequence of their fine particle size. The uncoated and fatty-acid-coated grades exhibit very poor interaction with polymer, so the modulus (a function of polymer-filler interaction) is very low, thus soft compounds are readily obtained. The high purity ensures that these fillers are very white and heat-ageing performance is superior to naturally derived calcium carbonates. One of the outstanding features of these fillers is their good high-temperature tear resistance [60]. 

Lianzhou Hong, Shu Bi, Ping Ning. Ultrafine ground calcium carbonate filled polypropylene. Plastics, 25(5) 31-35, 2006. 

High-whiteness marble, ball and calcined clays, anti-blocking agents, coated fine/ultrafine calcium carbonate, chalk whitings, alkaline high purity china clay... 

High brightness ultrafine ground and precipitated calcium carbonates are used as Ti02 extenders and opacifiers in water-based paints. They have a higher binder demand than filler grades, but better dry hide and gloss... 

PCC has high brightness, ultrafine particle size, and produces good gloss and printability. A major factor in the use of calcium carbonate is its cost. The product is relatively inexpensive yet of very high quality. 

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