The purpose of coating is to improve the quality and uniformity of the final printed product of paper or board, and the main goal of pigment coating is to obtain better optical properties, smoothness and gloss. The most important thing is to obtain better printing visual effects. Paper coatings are usually mainly composed of pigments, adhesives, additives and water. Among these components, the most important is the pigment, and many characteristics of the coated paper depend on the choice of the pigment.
Calcium carbonate is a widely sourced and inexpensive raw material. Due to its high whiteness and good fluidity, it is suitable for the preparation of high-solid content coatings; the demand for adhesives is low, which can improve the ink absorption of the coating; it can provide good whiteness and color tone, and improve air permeability; yes One of the most commonly used coating pigments.
Heavy calcium carbonate has better fluidity than light calcium carbonate and saves the amount of sizing material in coatings. It is suitable for papermaking coatings with high solid content and high proportions that require more and more.
Due to the high manufacturing cost of light calcium carbonate, the rheology is relatively poor. Therefore, it cannot compete with ground calcium carbonate in the application of coating pigments. The application of light calcium carbonate in paper coating pigments is mainly to make up for the deficiency of kaolin and heavy calcium carbonate. Generally used for low weight coated base paper, high gloss coated paper and matte coated paper.