For ultra-fine calcium carbonate, the crystal form is also a very important technical indicator.
Ordinary light calcium carbonate is spindle-shaped. If it is used in PVC plastics, it will cause greater stress and make the plastic film white. As ultrafine calcium carbonate, different crystal products should be produced according to different uses.

For ultrafine calcium carbonate used in plastics, its crystal form requires a simple structure, a smaller stacking volume, and a lower oil absorption value, so a cube or a sphere is better. Superfine calcium carbonate with a particle size of 0.072μm has a certain enhancement effect on PVC plastics, which can make the surface of the product fine and clean, with good gloss and good electrical insulation performance. It is used in flexible cable materials, and can maintain its performance in compliance with the standards stipulated by the state when the filling amount is more than doubled. Used in plastic film, it can reduce the whitening phenomenon and improve the low temperature elongation; used in hard plastics, such as plastic doors and windows and various profiles, can improve the impact strength, so that the notch impact strength can reach 49.1kJ/m2.
The ultrafine calcium carbonate used for rubber has the best chain-like reinforcement performance. Chain-like ultrafine calcium carbonate is formed by combining several or even dozens of calcium carbonate grains in one direction. It has a spatial three-dimensional structure in rubber and has good dispersion. When mixed with rubber, calcium carbonate chain breaks, forming an active cross section, which is more firmly bonded to the rubber chain, thereby greatly improving its reinforcing effect in rubber. The reinforcement properties of ultra-fine calcium carbonate with different shapes in rubber from strong to weak are as follows: chain shape, needle shape, spherical shape, cubic shape.
The ultrafine calcium carbonate used for ink is best in cubic shape, which is also determined by the nature of the ink. In resin ink, after filling with ultrafine calcium carbonate, it has high gloss, good transparency and good fluidity. The cubic shape is the most favorable to the gloss of the ink.
Precipitated calcium carbonate for papermaking coating generally does not belong to the category of ultrafine calcium carbonate, and its particle size is mostly in the range of fine calcium carbonate (particle size 0.1 ~ 1μm), but there is one thing in common, that is, there are certain requirements for the crystal form. Such as opacity (hiding rate), high viscosity density, whiteness, and ink absorption performance. Therefore, lamellar crystal form and cubic crystal form are more ideal.

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