China clay based surface coatings have been used in the paper industry for many years to enhance the surface of paper for printing applications. Two-side clay coated papers are used in huge volumes for printing magazines.
The surface coatings are primarily composed of a pigment (china clay – but other pigments such a calcium carbonate may also be used) and a binder (generally a synthetic latex such as SBR or PVAc), in a formulation not dissimilar to emulsion paint.
When applied to the surface of the paper at typically 10 – 20 GSM dry, the coatings can provide a smooth, even surface with improved ink holdout for printing purposes.
By increasing the binder to pigment ratio and carefully selecting the ingredients to ensure they are compatible with the intended silicone coating systems, clay coated papers can provide an ideal substrate for silicone coating and release paper manufacture.
Historically, clay coated release base papers have been extensively used for self-adhesive sheet laminate and computer-stock labels, where lay-flay characteristics are important. For industrial release applications, clay coated papers offer an interesting compromise in performance and properties between supercalendered papers and polyethylene coated papers.
Largely for traditional reasons, clay coated papers have had limited penetration in the industrial release market, although they are available in a wide range of substances and can be one or two side siliconised.
Clay coated kraft is most commonly used for the following applications:
If you would like to discuss the use of Cotek’s clay coated kraft in your product manufacturing process, get in touch with our friendly team today.