Studies on the fold-ability of coated paperboard (I): Influence of latex on fold-ability during creasing/folding coated paperboard

Papers consist more than 50% of the packaging material. Cartons which have been used for high quality hygiene packaging such as confections and cosmetics are made from coated paperboard. Carton-making process consists of printing on coated paperboard, creasing and then folding it. A frequently occurred trouble in a carton-making process is cracking along a creasing rule during creasing by high mechanical pressure. In order to reduce cracking and improve fold-ability of coated paperboard, this study elucidated the factors affecting cracking in a coated layer which absorbs most of elongation force applied on the surface layer of coated paperboard. Coated paperboard produced with latex having low Tg and small particle size showed good printability, flexible coated layer and consequently reduced cracking due to its good film formability. When the coated paperboard was folded in machine direction, the fold-ability was poor because of fiber orientation.