Coating composition and coated paper and coated paperboard

Abstract

A coating composition may include kaolin having a shape factor less than about 70 and calcium carbonate, wherein less than about 90% by weight and greater than about 60% by weight of particles of the calcium carbonate have an equivalent spherical diameter (esd) less than 2 microns. The coating composition may include a thickener present in an amount ranging from about 0.1% to about 0.9% by active dry weight of the composition. A coating composition may include kaolin having a shape factor less than about 70 and calcium carbonate having a mean particle size (d50) of at least about 2.4 microns and a steepness factor of at least about 30. The coating composition may be a paper basecoat composition or a paperboard basecoat composition. A paper or paperboard product may include the coating composition on at least one surface of the paper product or paperboard product.

Description

CLAIM OF PRIORITY[0001]This PCT International Application claims the benefit of priority of U.S. Provisional Application Nos. 61 / 787,222, filed Mar. 15, 2013, and 61 / 715,628, filed Oct. 18, 2012, the subject matter of both of which is incorporated herein by reference in their entireties.FIELD OF THE DISCLOSURE[0002]The present disclosure relates to coating compositions, and more particularly, to coating compositions for paper and paperboard products.BACKGROUND OF THE DISCLOSURE[0003]Coatings may be applied on substrates to enhance the physical and optical properties of the substrate. For example, paper and paperboards used in the printing and converting industries may be subjected to a variety of operations, such as, for example, printing, cutting, creasing, folding, and / or gluing. Coated paperboards are widely used in the packaging industry, and a typical coating formulation may include one or more pigments, binders, and additives. Such coatings may serve to enhance physical, optic...

AI Technical Summary

Benefits of technology

The patent text describes a coating composition that includes a combination of kaolin and calcium carbonate particles. The composition has a specific shape factor and a steepness factor that affect its properties. The coating composition can be used in paper and paperboard products to provide improved properties such as smoothness, gloss, and durability. The technical effects of the coating composition include improved print quality, reduced paper roughness, and improved resistance to wear and tear. The composition can also be used as a thickener in the coating.

Problems solved by technology

However, creasing and folding may result in applying significant strains to the paper or paperboard substrates.

Such strains challenge the mechanical strength of the substrates as well as any coating layers present on the substrates.

For example, rupture occurring at creased and folded edges of the paper and paperboard products may weaken barrier properties of the substrate significantly and may diminish the overall aesthetic appeal of a packaging formed by the substrate.

An inability to withstand these large strains may lead to rupture of folded edges, potentially resulting in large cracks or flaking-off of the coating layer or both.

However, stiffer coating layers may tend to increase the severity of cracking or flaking occurring at folded edges of paper or paperboards.

Images