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The Shiraishi Group has acquired know-how in fillers through many years of business. We utilize this know-how to implement an integrated system spanning from development to blending, processing, molding and evaluation of physical properties.


Shiraishi Central Laboratories develops and evaluates calcium carbonate for rubber, as well as various fillers and additives.
Calcium carbonate contributes to processability, reinforcement, economy, and various other properties required for rubber products. In terms of economy, kneading ground calcium carbonate into raw rubber contributes to reduced raw material costs while maintaining the same hardness of rubber products. Spindle-shaped precipitated calcium carbonate creates the appropriate amount of softness and smoothness in rubber fabric.
In addition, rubber can be reinforced by using fine calcium carbonate of 200 nm or less. Normally, fine particles agglomerate with each other, which results in poor dispersion. However, by using surface treatment technology which we have cultivated thus far, the Shiraishi Group prevents the poor dispersion by treating the surface of calcium carbonate with organic substances. In addition, activated calcium carbonate with a size of 20 nm increases the mixing speed for carbon black, silica, and other substances which tend to require a long time to be kneaded into raw rubber. This is useful for improving dispersibility.
Shiraishi Central Laboratories has a Banbury mixer, roller, heating press, and various machines for testing physical properties. In addition to the development of fillers, the laboratory has integrated processes from blending to processing, molding, and evaluation of physical properties, while also developing new fillers and additives at the same time.

Electron microscope image of activated calcium carbonate (particle diameter = 20 nm)

Dispersion state of carbon black in rubber

Rubber being kneaded

Campos de Investigación