塗料の保水性が塗工紙物性に与える効果 （第２報） 塗料中のラテックス浸透

Abstract

The water retention of coating color on base paper is one of the most important properties that affect the sheet properties of coated paper. However, we do not have any standard to evaluate water retention of coating color even though some methods have been suggested to evaluate water retention of coating color. We divided “Water Retention” into static water retention and dynamic water retention and evaluated coating runnability by the two kinds of water retention.In this study, we measured water loss rate of actual coatings and dilute latex emulsions, a common part of typical coatings. We suggested a new concept “Interactive Water Retention”, which is calculated from these water loss rates. Interactive Water Retention and water loss ratio were used as an index to evaluate the coating properties.Binder in a coating color penetrates into base paper when the coating color is applied. Binder in coating goes through a filter and also penetrated into filter papers when water loss ratio is measured under pressure. This binder (SB-latex) penetration is measured by reflected ultraviolet absorption. We suggested new concepts “Total Latex Loss” and “Penetrating Latex Loss”, which are calculated from these signals and the depth of latex penetration. We also suggested new concepts “Interactive Latex Retention I”, which is calculated from a “Total Latex Loss” of a coating and a latex solution, and “Interactive Latex Retention II”, which is calculated from a “Penetrating Latex Loss” of a coating and a latex solution. Total Latex Loss, Penetrating Water Loss, Interactive Latex Retention I and II were used as an index to evaluate the coating properties.Water Loss Rate, Interactive Water Loss, Total Latex Loss, Penetrating Latex Loss, and Interactive Latex Retention I and II were different from each other and apposite to evaluate coating color.